Earticle

The purpose of this study was to examine the perspectives of pre-service teachers on ELT textbook evaluation and adaptation to provide a better understanding of what they might face and experience when selecting and implementing teaching materials in their own classrooms. A total of 75 pre-service teachers across three different majors participated in data collection through a course on Materials Study. The main methods for data collection included open-ended surveys, reflection papers, and course-related documents. A mixed-method approach was applied to examine the factors influencing the pre-service teachers’ English textbook evaluation and adaptation and to identify the challenges they encountered. The study found that pre-service teachers valued textbook evaluation for understanding material strengths and weaknesses but faced challenges such as ambiguous criteria, difficulties in creating checklists, and textbook similarities. In adapting materials, they preferred modifying and adding content rather than removing or replacing it, with frequent adaptations in Music and English, particularly for language simplification. The main reason for adaptation was to enhance student interest and motivation, while external factors like classroom management and time constraints were less influential. These findings highlight the need for structured training in textbook evaluation and adaptation, emphasizing a student-centered approach to ensure engaging and relevant instructional content.

The purpose of this study was to investigate the views of in-service and pre-service teachers on a graduate course of ELT materials evaluation and development in order to have a better understanding of what teachers might face in selecting and developing teaching materials. The main methods for data collection were reflection papers(of material evaluation and development), open-ended surveys, individual interviews with the teachers, and documents related to the course. Qualitative methodology as well as quantitative methodology were applied to examine what might govern the teachers’ process of material evaluation and development, and find out which difficulties the teachers experienced in doing this. The results of the study revealed that first of all, the principles of language teaching and learning held by the teachers were likely to have a propounding influence on their approach toward the evaluation and development process. The study also showed that experience of conducting hands-on evaluation of materials raised the teachers’ awareness of what aspects of materials they should pay more attention to when evaluating materials for selection or adaptation. Along with the evaluation, creating materials by following up the systematic steps resulted in positive reactions from the teachers in terms of gaining knowledge as well as professional development

The stone lantern of the Damyang Gaeseonsaji temple site is a cultural heritage built during the Unified Silla period (AD 868). The reason for its value as a cultural property is due to wittern the background and the period created on inscription of the lamp stone engraved by letters. The stone lantern consists of two types of lithic tuffs for the 23 original properties, the replaced stones in 1991, and the biotite granite for its ground stones replaced in 2005. The lithic tuffs selected as the replacement parts in 1991 and 2017 have been examined and got to properties of hardly exposure moisture as well as very similar geochemical characteristics. There were various types of physical deterioration of the stone properties and structural cracks; in particular, on the northern side of the stylobates. Chemical and biological deterioration can be identified as black, white, and brown discolorations as well as by the presence of lichens, bryophytes, and herbaceous plants. In the evaluation of the physical properties of the stone lantern, the mean and maximum ultrasonic velocities were found to be similar in each direction. However, the lowest velocity on the east and south sides were found to be lower than those of other stone properties. It was found that physical damage to the stylobates resulted from water expansion in a freeze-to-thaw phenomena related to water content. Therefore, dismantling repair was carried out in the protection facility to restrict further water supply to the stone as much as possible.

목적: 딜(dill)은 동아시아에서 유명한 약용식물로 에센셜 오일 추출을 통해 건강 증진에 사용되고 있다. 이에 본 연구는 Anethum graveolens L. (dill)의 에탄올 추출물이 피부에 미치는 생리활성 효과를 확인하였다. 방법: 분쇄한 딜을 70% 에탄올로 24 h 동안 추 출하였다. 추출물을 진공 펌프를 통해 여과한 후 농축 및 동결건조를 통해 제조하였다. 딜 에탄올 추출물의 피부 세포들을 이용하여 항산화, 항염, 멜라닌 함량 및 수분 공급 변화를 평가하였다. 결과: 딜 추출물의 항산화 활성을 확인한 결과 라디칼 소거 활성이 증 가하는 것을 확인하였다. 또한, 딜 추출물의 NO 생성 억제 활성을 통해 항염 효능을 확인하였다. 또한, 추출물이 멜라닌 생성 저해 활성 및 히알루론산 발현 증가를 통해 유효성을 검증하였다. 결론: 본 연구는 딜 추출물의 피부 생리 활성 특성을 유의하게 확인하 였으며 화장품 및 식품 등의 소재로 활용 가능성이 있음을 시사하였다.

Purpose: Anethum graveolens L., commonly known as dill, is a popular herbal medicine in East Asia. Dill is reportedly a rich source of essential oils, vital for health. This study aimed to examine the effects of ethanol extracts of Anethum graveolens L. (dill), on the physiological activities on the skin. Methods: After extracting ground dill with 70% ethanol for 24 hours, the extracts were filtered through a vacuum pump, concentrated using an evaporator and lyophilized. The dill ethanol extracts (DEE) evaluated the effects on antioxidants, cytotoxicity, anti-inflammatory, melanin content, and hydration effects in skin cell lines. Results: Results of DPPH and ABTS assay indicated that DEE was observed to increase radical scavenging activities. Measurements of cytotoxicity of DEE indicated that DEE significantly inhibited nitric oxide production and melanin content. Also, DEE increased the hyaluronic acid production by approximately 18.75% compared with control. Conclusion: Our research confirmed the effect of DEE on skin physiological properties and that it can be considered for developing functional foods or cosmetics.

目的: Anethum gravolelens L.，俗称莳萝，是东亚流行的草药。据报道，莳萝是精油的丰富来源，对健康至关 重要。本研究旨在探讨莳萝乙醇提取物对皮肤生理活动的影响。方法: 用70%乙醇提取磨碎的莳萝24 h后，通过 真空泵过滤提取物，使用蒸发器浓缩并冻干。莳萝乙醇提取物(DEE)评估了其对皮肤细胞系的抗氧化剂、细胞毒 性、抗炎、黑色素含量和水合作用的影响。结果: DPPH和ABTS测定结果表明，观察到 DEE 增加自由基清除活 性。DEE的细胞毒性测量表明，DEE显着抑制一氧化氮的产生和黑色素含量。此外，与对照相比，DEE使透明质 酸的产量增加了约18.75%。结论: 我们的研究证实了DEE对皮肤生理特性的影响，可以考虑将其用于开发功能 性食品或化妆品。

본 의료기관에서 사용되는 방사선 차폐체는 주로 납을 활용하여 제품과 부속품을 제작한다. 납은 가공성과 경제성이 우수하지만 폐기 시 환경 문제로 인해 사용량을 줄이고 있으며, 오랫동안 사용했을 시 크랙 현상과 중력 에 의한 처짐 현상으로 인해 차폐막, 차폐벽, 의료기기 부픔 등으로 장기간 사용하기에는 한계가 있다. 이러한 문 제점을 해결하기 위해 구리, 주석 등을 사용하지만, 아직 차폐성능을 제어하기에는 제작 공정에 어려움이 있어 대부분 텅스텐을 많이 사용하고 있다. 그러나 아직 텅스텐의 종류에 따른 특성이 잘 제시되지 못해 다른 차폐재와 의 비교가 어렵다. 따라서 본 연구에서는 순수 텅스텐, 탄화텅스텐, 산화 텅스텐을 이용하여 동일한 공정으로 의료 방사선 차폐시트를 제작하여 시트 단면의 입자 구성과 차폐성능을 비교하였다. 비교 결과 순수 텅스텐, 탄화텅스 텐, 산화 텅스텐 순으로 차폐성능이 우수한 것으로 나타났다.

Radiation shields used in medical institutions mainly use lead to manufacture products and fitments. Although lead has excellent processability and economic efficiency, its use is being reduced due to environmental issues when it is disposed of. In addition, when used for a long time, there is a limit to using it as a shielding film, shielding wall, medical device parts, etc. due to cracking and sagging due to gravity. To solve this problem, copper, tin, etc. are used, but tungsten is mostly used because there is a difficulty in the manufacturing process to control the shielding performance. However, it is difficult to compare with other shielding materials because the characteristics according to the type of tungsten are not well presented. Therefore, in this study, a medical radiation shielding sheet was manufactured in the same process using pure tungsten, tungsten carbide, and tungsten oxide, and the particle composition and shielding performance of the sheet cross-section were compared.As a result of comparison, it was found that the shielding performance was excellent in the order of pure tungsten, tungsten carbide, and tungsten oxide.

목적: 국화과(Compositae)의 한 품종인 감국(Chrysanthemum indicum Linne)은 예로부터 전통적인 약초로 사용되어 왔다. 감국의 다양한 생물학적 기능이 보고 되었음에도 불구하고 미용기능식품과 화장품 소재로서 의 역할과 기능은 명확하게 밝혀지지 않았다. 그러므로, 본 연구에서 우리는 감국 물 추출물(CIW)을 제조하고 항산화 활성, 지방축적 억제활성 및 human skin fibroblasts (HSF) 세포에서 피부 섬유에 관련된 유전자들의 조절 기능을 통해 감국 추출물의 미용기능식품 및 화장품 소재로서의 가능성을 평가하고자 한다. 방법: CIW의 항산화 활성은 금속 킬레이팅 활성과 환원력으로 평가하였다. 3T3-L1 세포 및 HSF에서 CIW의 세 포독성은 MTT assay로 평가하였다. CIW의 지질축적 억제활성은 Oil Red O (ORO) 염색법 및 현미경 관찰을 통해 수행하였다. HSF 세포에서 피부 섬유와 관련된 유전자들의 mRNA 발현 수준은 RT-PCR 분석법을 통해 평가하였다. 결과: 금속 킬레이팅 활성 및 환원력을 통한 CIW의 항산화 활성은 농도 의존적으로 증가하였다. 3T3-L1 세포 와 HSF에서 CIW를 24 h 동안 처리하였을 때, 100 µg/mL 이하의 농도에서는 세포독성이 발견되지 않았으며, 이후 세포실험에서는 100 µg/mL 이하의 CIW를 사용하였다. 3T3-L1 세포에서 CIW를 10, 50, 100 µg/mL의 농 도로 처리하였을 때, 유의적인 지방축적 억제활성을 나타냈으며, CIW를 처리한 HSF 세포에서 fibronectin와 COL1A2와 같은 피부 섬유와 관련된 유전자의 mRNA 발현 수준을 상향조절 하였다. 결론: 본 연구결과는 CIW가 미용기능식품 및 화장품 소재로서 활용될 수 있음을 시사한다

Purpose: Chrysanthemum indicum Linne (CI) has been used as a traditional medicine. Although several biological effects of CI have been reported, the precise role and function of CI as nutri-cosmetic and cosmetic materials remain unclear. Therefore, we prepared water extract of Chrysanthemum indicum Linne (CIW). And nutri-cosmetic potential was discussed through evaluation of anti-oxidant, anti-adipogenic in 3T3-L1 cells and regulatory function of skin fibril-related genes in human skin fibroblast (HSF). Methods: The anti-oxidant activity of CIW was evaluated through metal chelating activity and reduction potential. The cytotoxicity of CIW in 3T3-L1 and HSF was evaluated by MTT assay. The anti-adipogenic effect of CIW was examined by Oil Red O (ORO) staining and microscopy observation in 3T3-L1 cells. The mRNA expression levels of skin fibril-related genes in HSF were analyzed by reverse transcription-polymer chain reaction (RT-PCR). Results: The anti-oxidant activity of CIW was increased in a dose dependent manner. The CIW treatment up to 100 µg/mL for 24 h did not affect to the viability of 3T3-L1 cells and HSF. Thus, up to 100 µg/mL of CIW was chosen in cell-based assay. The treatment of 10, 50, and 100 µg/mL CIW significantly inhibited 3T3-L1 adipogenesis by 5.17%, 72.80%, and 104.09%. In addition, up-regulated mRNA expression levels of skin fibril-related genes such as fibronectin and type Ⅰ collagen α2 (COL1A2) were observed in CIW-treated HSF. Conclusion: These results suggest that CIW has the potential as nutri-cosmetic and cosmetic ingredient which possess anti-oxidant and anti-adipogenic effects.

目的: 菊科植物的一种野菊花已被用来作为一个传统医药。虽然野菊花有很多种生理活性，但是作为美容功能 食品和化妆品原料的作用和功能还没有完全明确。因此通过评价菊花提取物（CIW）的抗氧化活性和抑制脂肪 形成以及在HSF细胞中皮肤纤维相关的基因的调节功能，进一步调查作为美容功能性食品原料及化妆品原料的 可行性。 方法：CIW的抗氧化活性通过金属螯合活动和还原力来评价。3T3-L1细胞和HSF中CIW的细胞毒性利用MTT assay来评价。CIW的抑制脂肪堆积活性通过 Oil Red O (ORO)染色法和显微镜观察来判断。HSF细胞中对皮肤 纤维相关的基因的mRNA表达水平利用RT-PCR分析法来评价。 结果: 通过金属螯合活动和还原力评价的CIW的抗氧化活性随着浓度增加而增加。对3T3-L1 和HSF用CIW经过 24h处理，在CIW200 μM 以下时，3T3-L1细胞和HSF生存率几乎没有影响。因此在以后的细胞实验中使用了100 μM CIW。对3T3-L1细胞分别用CIW10，50，100 μg/mL处理时出现了明显抑制脂肪堆积活性。此外用CIW处理 的HSF细胞中Fibronectin和COL1A2相关的皮肤纤维基因的mRNA表达水平也提高了。 结论: 通过研究CIW作为美容功能食品及化妆品原料具有充分利用的价值。

전무산조와 SBR (Sequencing Batch Reactor)이 결합된 공법에 있어서 3가지 다른 운전 주기 경과시간에 따른 성능을 EQPS (Effluent Quality Predication System)를 이용해 파악하였다. 동일한 유입수 및 반응조 조건에서 4시간, 5시간 및 6시간 주기 경과 시간에 있어서의 TOC (Total Organic Carbon)를 포함한 유기물 제거 효율은 동일한 것으로 나타났지만, 총 질소 제거 효율은 6시간 주기에서 가장 높고, 이 주기에서의 잉여슬러지 발생량은 가장 적은 것으로 나타났다. 그리고 6시간 주기에서 요구되는 유량조정조 체적은 4시간 주기에 비해 50% 큰 것으로 나타났다. 그러므로 전무산소와 결합된 SBR 공법은 각 주기에 따른 운전 효율 및 요구되는 유량조정조 체적을 고려해 설계가 수행되어야 한다.

The performance of SBR with Pre-Aniox Tank was evaluated by EQPS (Effluent Quality Predication System) according to 3 different time steps : 4, 5 and 6 hours. For organic materials including TOC (Total Organic Carobon), all three time steps show same removal efficiencies. However, nitrogen removal efficiency is highest and WAS (Waste Activated Sludge) amount is lowest at 6 hour cycle. It is found that 6 hour cycle time steps requires 50% more volume of equalization basin located before SBR with Pre-Aniox Tank than volume for 4 hour cycle duration. When the SBR with Pre-Anoxic Tank is designed, the time steps has to be determined after considering operational performance and required volume of equalization basin.

As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. BI(Ball Indentation) test has a potential to replace conventional fracture tests like a uniaxial tensile test, fracture toughness test, hardness test and so on. In this paper, we would like to present the ageing evaluation technique by the BI method. The four classes of the thermally aged 1Cr-!mo-0.25V specimens were prepared using an artificially accelerated aging method. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed. The results of the BI tests were in good agreement with fracture characteristics by a standard fracture test method within 5%. The IDE(Indentation Deformation Energy) of a BI technique as a new parameter for evaluating a degradation was suggested and the new IDE parameter clearly depicts the degradation degree.

The nondestructive evaluation system consisted of a ball indentation tester and a ultrasonic tester was developed to evaluate material properties. The relations between the parameters from test results using the system and the results of tensile and fracture toughness tests were investigated. The fracture toughness and tensile properties could be determined using the system. Some metallic materials were experimented to predict the fracture toughness and tensile properties and verify the relations between them. The predicted fracture toughness and tensile properties show a good agreement with the results obtained by conventional tests. It is found that the material properties and the material degradation can be evaluated using the nondestructive evaluation system.

The objective of this study is to assess the environmental effect of the reclaimed land drainage method using oyster shell through the Life cycle $CO_2$ assessment, and to evaluate the applicability in South Korea. In this Study, the life cycle $CO_2$ emissions of oyster shell (OS) and crushed stone (CS, as avoided product) were assessed and compared. The Life Cycle Assessment method was used for quantitative evaluation of direct or indirect environmental effects of OS recycling. $CO_2$ was selected as the evaluation target material, and the scope of assessment includes the acquisition of materials, processing, transportation, construction phases. Compared to using CS, 77.0% of $CO_2$ emissions in acquisition and processing, 47.0% in transportation and 6.5% in construction phase were reduced, respectively by using of OS. The maximum transportation distance of OS was estimated according to transportation distance of CS. OS has environmental advantages than CS within about 26 - 101 km from the source. OS was found to be applicable to reclaimed lands up to 810 ha, 3,910 ha from Tongyeong and Yeosu, respectively. In addition, the amount of OS that could be used as drainage material for reclaimed land was much higher than annual OS production of South Korea. Therefore, it is considered that OS is sufficient to be used as drainage material for reclaimed land in South Korea.

PURPOSES : The objective of this study is to evaluate the tack-coating material's properties using the bitumen bond strength(BBS) test and damping test as function of changed curing times. In this study, bonding strength tests were performed according to the curing time of tack coating materials. METHODS : In order to investigate bonding characteristic of tack coating materials, the Pneumatic Adhesion tensile Testing Instrument(PATTI) device is used to measure the bond strength between the tack coating materials and aggregate substrate based on the AASHTO TP-91. Also, damping test as in situ test was used to determine an appropriate traffic openting time for construction vehicle. Four different tack-coating materials were used in this study. The BBS tests were performed a one hour curing and testing temperatures of $5^{\circ}C$, $15^{\circ}C$, and $25^{\circ}C$. Damping test was conducted at 30min, 60min, 90min, and 120 min of curing times with temperatures of $20^{\circ}C$ and $30^{\circ}C$. RESULTS and CONCLUSIONS : The BBS test results show various bond strength as function of tack coat materials. At the same testing condition, A tack coat material shows almost two times higher than D tack coat materials although both materials are satisfied the criteria of material's physical properties. Also, Dampting test results shows similar trend with BBS test result. The damping test result was significantly changed as function of tack coat materials. Based on this study, the tack coating material's curing time is very important. Therefore, both curing time and the bond strength's characteristic has to be considered in standard specification.

국내의 경우 도로포장설계시 외국의 설계법을 단순히 도입하여 사용하고 있지만 건설재료, 기후 및 교통조건 등이 외국과 상이하기 때문에 근본적인 제한성이 있다. 특히, 국내 포장구조해석에서 아스팔트층 거동특성만을 중요시하는 해석은 포장구조체가 각 층의 영향을 받는 종합적인 거동특성을 보인다는 포장구조체 시스템적인 특성을 고려한다면 많은 문제점을 내포하고 있다. 따라서, 도로포장 설계시 합리적이고 경제적인 설계를 할 수 있도록 포장구조체의 해석시스템을 구축하여야 한다. 본 연구에서는 포장하부의 다층구조로서의 역학적 거동을 정확히 해석하기 위하여 비파괴 시험장비인 FWD(Falling Weight Deflectometer) 를 이용하여 층 재료 자체의 성질을 대변하는 모델 중 포장하부를 구성하는 재료에 대한 비선형 탄성모델의 적용성을 검토하고, 복잡한 실험을 통해 얻게되는 비선형탄성모델의 구성인자인 재료상수를 FWD 시험자료로부터 직접 추정하는 체계를 제안하였다. 먼저, FWD 시험의 비선형성을 고찰하고, 실내 $M_R$ 시험을 통해 결정되는 재료상수를 현장에서 수집된 FWD 자료로부터 추정하는 체계를 제안하였다. 제안된 체계로부터 추정된 재료상수는 실내시험을 통해 제안된 국내 보조기층의 재료상수 범위 내에 있음을 알 수 있었다. FWD 를 이용한 비선형모델 적용의 신뢰성을 검증하기 위하여 깊이별 처짐 측정장비인 MDD(Multi-Depth Deflectometer) 현장시험자료를 이용하였다. 검증결과, 본 연구에서 제안한 비선형탄성모델을 적용한 방법이 기존의 선형탄성모델보다 실제 MDD 실측값에 더 가까운 결과를 나타냄을 알 수 있었다.

This study examines which models are more suitable for representing mechanical property of unbound materials to analyze behavior of asphalt pavement structure. Results from FWD (Falling Weight Deflectometer) test were used to apply to nonlinear elastic model. The new method which can deduct material constants of nonlinear elastic model is suggested from FWD test data rather than laboratory resilient modulus ($M_R$) test. It is confirmed that the material constants are within the common range in subbase. Test output from FWD and MDD (Multi-Depth Deflectometer) was used to verify reliability of the model. From the results of verification, this study shows that a non-linear elastic model agrees to MDD test data more than a linear elastic model does.

본 연구는 우리나라의 자원생산성(및 원재료 생산성), 물질순환이용율, 디커플링팩터 등의 3가지 지표를 산정하는 것을 통해 국내 경제활동과 자원소비간의 지속가능성을 평가하고 탈물질화 정도를 살펴보았다. 우리나라의 자원생산성은 2000년 1.32백만원/톤에서 2007년 1.61백만원/톤으로 22% 증가하였으며 2000년~2007년간 자원생산성 연평균증가율은 2.88%로 나타났다. 원재료물질투입량은 국내물질소비량(DMC)의 약 73%~76%를 차지하고 있으며, 원재료생산성은 2007년 2.11백만원/톤으로, 2000~2007년간의 연평균증가율은 3%로 나타났다. 배출된 폐기물은 재활용 및 에너지화를 통해 경제계로 순환되는데 국내 물질순환이용율은 2000년 10.9%에서 2007년 15.6%로 증가하였으며, 2000년부터 2007년까지 연평균 5.3% 수준으로 증가하였다. 그러나 전년대비 증가율의 변화율이 점차 감소하고 있는 추세로 나타났다. 또한 우리나라 경제활동과 자원소비량 간의 디커플링이 발생하여 탈물질화로 진행하고 있음을 확인할 수 있었다.

This study calculated the three indices of Korea’s resource productivity (and raw material productivity), material circulation rate and decoupling factor to evaluate the sustainability of domestic economic activities and resource consumption and examine the extent of dematerialization. Korea’s resource productivity improved 22% from 1.32 million KRW/ton in 2000 to 1.61 million KRW/ton in 2007, with the annual average growth of resource productivity during the period standing at 2.88%. Raw material inputs accounted for 73-76% of domestic material consumption (DMC); raw material productivity for the year 2007 was 2.11 million KRW/ton, growing 3% on annual average from 2000 through 2007. The wastes released are circulated into the economic system through recycling and energization. Korea’s material circulation went up from 10.9% in 2000 to 15.6% in 2007, growing by an annual average of 5.3% during the period. The rate of change in year-on-year growth, however, was found to be on the gradual decrease. This study also showed that Korea’s economic activities were decoupled with its resource consumption as the country heads toward dematerialization through sustainable resource management.

본 연구에서는 콘크리트 부재에 저온 적용을 위해 SOL-GEL 기법을 이용하여 제조된 열에너지 저장 복합상변화물질(CPCM)를 개발하였다. 코어는 테트라데칸, 지지재는 활성탄(AC)을 각각 사용하였다. 진공 함침법을 이용하여 AC의 다공성 구조에 테트라데칸 상변화 물질(PCM)을 함침시키고, 테트라에틸오르토실리케이트(TEOS)를 사용한 SOL-GEL 공정을 이용하여 제조된 복합체에 실리카 겔을 얇게 코팅하였다. CPCM의 열 성능은 시차주사열량계(DSC)과 열 중량분석(TGA)을 통해 분석했다. DSC 결과 테트라데칸 PCM은 용융 및 동결 온도가 각각 6.4℃ 및 1.3℃이고 해당 엔탈피는 각각 226J/g 및 223.8J/g인 것으로 나타났다. CPCM은 7.1℃ 및 2.4℃에서 용융 및 동결 과정에서 각각 32.98J/g 및 27.7J/g의 엔탈피를 나타내었다. TGA 시험 결과 AC는 500℃까지 열적으로 안정하며, 이는 120℃ 정도인 순수 테트라데칸의 분해 온도보다 훨씬 높은 것으로 나타났다. 또한, AC-PCM과 CPCM의 경우 각각 80℃와 100℃에서 열분해가 시작되었다. CPCM의 화학적 정성 분석을 위해 푸리에 변환 적외선(FT-IR) 분광법을 이용하였으며, 그 결과 개발된 복합체가 화학적으로 안정함을 확인하였다. 마지막으로, SOL-GEL 공정 후 AC 표면에 실리카 겔의 얇은 층이 존재함을 확인하기 위해 주사전자현미경(SEM)을 이용하여 AC와 CPCM의 표면 형태를 분석하였다.

In this study, a composite phase change material (CPCM) produced using the SOL-GEL technique was developed as a thermal energy storage medium for low-temperature applications. Tetradecane and activated carbon (AC) were used as the core and supporting materials, respectively. The tetradecane phase change material (PCM) was impregnated into the porous structure of AC using the vacuum impregnation method, and a thin layer of silica gel was coated on the prepared composite using the SOL-GEL process, where tetraethyl orthosilicate (TEOS) was used as the silica source. The thermal performance of the CPCM was analysed using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC results showed that the pure tetradecane PCM had melting and freezing temperatures of 6.4℃ and 1.3℃ and corresponding enthalpies 226 J/g and 223.8 J/g, respectively. The CPCM exhibited enthalpy of 32.98 J/g and 27.7 J/g during the melting and freezing processes at 7.1℃ and 2.4℃, respectively. TGA test results revealed that the AC is thermally stable up to 500℃, which is much higher than the decomposition temperature of the pure tetradecane, which is around 120℃. Moreover, in the case of AC-PCM and CPCM thermal degradation started at 80℃ and 100℃, respectively. The chemical stability of the CPCM was studied using Fourier-transform infrared (FT-IR) spectroscopy, and the results confirmed that the developed composite is chemically stable. Finally, the surface morphology of the AC and CPCM was analysed using scanning electron microscopy (SEM), which confirmed the presence of a thin layer of silica gel on the AC surface after the SOL-GEL process.

최근 택코트 부착성능의 중요성이 높아지며 시공과정에서의 택코트 손실을 방지하기 위해 동시포설공법이 제안되고 있다. 동시포설공법은 아스팔트 페이버에 택코트 살포장치를 부착하여 택코트 살포와 동시에 아스팔트 혼합물을 포설하는 공법이다. 노후 콘크리트 포장의 아스팔트 덧씌우기 포장은 강성포장 위에 연성포장이 적용되기 때문에 이질적인 재료에 따른 부착성능의 확보가 더욱 중요하다. 이에 따라 동시포설공법으로 적용이 가능하고 이질적 재료에도 충분한 부착성능을 나타내는 택코트 재료가 필요하게 되었다. 본 연구는 동시포설공법을 위해 개발된 택코트 재료의 기초성능을 평가하기 위해 다양한 조건의 부착강도 실험을 수행하였다. 부착성능 평가결과 양생조건과 택코트 손실에 의해 부착성능에 차이가 발생함을 알 수 있었으며, 개발 재료는 동시포설공법과 동일한 시공조건 모사 실험에서 기존 재료 대비 인장접착강도 1.21배, 전단부착강도 1.99배 높은 부착성능을 나타내어 동시포설공법에 적용하기에 적합한 것으로 나타났다.

Spray paving minimizes material lost during the construction or repair of a road surface, and it can be done in conjunction with tack coating. This approach involves applying the asphalt mixture at the same time as spraying the tack coat by attaching a spraying device to the asphalt paver. When applying an asphalt overlay to an aged concrete surface, it is important to ensure the adhesion performance between different material properties. Accordingly, there is a need for a tack coat that can be applied by spray paving and that exhibits good adhesive performance on different materials. In this study, bonding strength tests under various conditions were performed to evaluate the basic performance of a tack coat developed for use with a spray paver. The bonding performance of the tack coat was observed to be affected by curing conditions and material lost during construction. The test results also showed that the tensile and shear bonding strengths of the developed tack coat were 1.21 and 1.99 times higher than those of a conventional one, respectively. As a result, the developed tack coat is considered suitable for application to spray paving.

Background: Mattresses are products designed for long-term use positioned in immediate proximity to the human breathing zone. However, their contribution to PM_2.5 resuspension during repeated use has not been well characterized. Objectives: This study aimed to quantitatively evaluate PM_2.5 resuspension characteristics from mattresses and assess differences by mattress material, dust loading, and aging duration. Methods: Laboratory experiments were conducted using mattress specimens made of airweb, memory foam, and latex. Standard test dust was applied at three loading levels (1, 2, and 4 g). Repeated mechanical loading was applied to simulate use, followed by controlled impact to induce resuspension. PM_2.5 concentrations were measured after impact. Aging durations of 0, 1, and 5 days were examined under a dust loading of 1 g. Results: Across all experimental conditions, airweb mattresses consistently showed lower PM_2.5 resuspension concentrations compared to memory foam and latex mattresses. For memory foam, peak PM_2.5 resuspension generally increased with greater dust loading, while resuspension in airweb remained low. In addition, latex mattresses exhibited a pronounced increase in PM_2.5 resuspension with longer aging duration, whereas changes in airweb mattresses remained minimal. Conclusions: PM_2.5 resuspension from mattresses varies markedly by material, accumulated dust, and use duration. These findings indicate that mattress material and usage-related factors may influence PM_2.5 exposure levels in bedroom environments. The results provide a basis for mattress selection and indoor air quality management to reduce inhalation exposure.

춘천 물로리 지역은 지방상수도가 보급되지 않은 물복지 소외지역으로 복류수 및 지하수를 수원으로 하는 소규모 급수시설로 마을에 물을 공급하고 있다. 최근 극심한 가뭄 발생시 물부족으로 인해 급수차에 의존하는 등 물공급 여건이 열악한 지역이다. 따라서 가뭄시 물부족 문제를 해결하고 증가하는 물수요에 대비하기 위해 계곡에 연하여 샌드댐을 설치하였으며, 2022년 5월부터 이 시설을 운영하고 있다. 본 연구에서는 2020년 3월 중순부터 2022년 3월 중순까지 약 2년 동안의 유입량 조건에 대해 채움재의 수리전도도와 저류계수 값 조건에 따라 반복 모의를 수행하였고, 각각의 경우에 대해 유공배수관을 통한 방류량을 산정하였다. 전반적으로 수리전도도가 증가할수록 방류량과 그 비율이 증가하나, 2층의 수리전도도가 상대적으로 가장 낮은 경우에는 3층의 수리전도도가 증가할수록 방류량이 증가하다가 작아지는 특이한 양상을 보였다. 이는 3층의 투수성과 배수관의 배수계수 값이 커서 3층으로의 순유입보다 빠른 배수로 인해 수위가 낮게 유지된데서 기인한 것으로 판단된다. 샌드댐 상부 개수로 흐름을 수리전도도가 매우 큰 가상의 지하수층으로 모사한 결과 가상층 수리전도도 증가율에 비해 방류량 감소는 둔화되지만, 가상층 수리전도도가 커짐에 따라 상대적으로 방류량이 줄어드는 양상은 명확하게 나타났다.

The Chuncheon Mullori area is an underprivileged area of water welfare where local water supply is not supplied, and it is supplying water to the villages with small water supply facilities using lateral flow and groundwater as water sources. This is an area with poor water supply conditions, such as relying on water trucks due to water shortages during the recent severe drought. Therefore, in order to solve the problem of water shortage during drought and to prepare for the increasing water demand, a sand dam was installed along the valley, and this facility has been operating since May 2022. In this study, repeated simulations were performed according to the hydraulic conductivity of the filler material and the storage coefficient value for the inflow condition for about two years from mid-March 2020 to mid-March 2022. For each case, the amount of discharge through the perforated drain pipe was calculated. Overall, as the hydraulic conductivity increased, the amount of discharge and its ratio increased. However, when the hydraulic conductivity of the second floor was relatively low, the amount of discharge increased and then decreased as the hydraulic conductivity of the third floor increased. This is considered to be due to the fact that the water level was kept low due to the rapid drainage compared to the net inflow into the third floor because the water permeability of the third floor and the drainage coefficient of the drain pipe were large. As a result of simulating the flow of the open channel in the upper part of the sand dam as a hypothetical groundwater layer with very high hydraulic conductivity, the decrease in discharge rate was slower than the increase in the hydraulic conductivity of the hypothetical layer, but it was clearly shown that the discharge volume decreased relatively as the hydraulic conductivity of the virtual layer increased.

Rolling contact fatigue (RCF) and wear caused by rolling contact between the wheel and rail are inevitable problems in railway systems. An increase in axle load or the slip ratio causes excessive wear. However, RCF and wear do not act independently, but one influences the other. Wheel and rail materials and manufacturing quality have a considerable influence on the formation of RCF and the ensuing wear. Therefore, the mechanical properties of the wheel and rail are important factors for reducing RCF and wear on the contact surface. This paper presents a comparative evaluation of the wheel and rail used in the Korean industry for high speed trains and conventional rails with respect to their fatigue and fracture behavior. A series of tests such as uniaxial tensile tests, fracture toughness tests, and fatigue crack growth tests were carried out at both room temperature and low temperatures.

충전(Backfill)은 재료와 이송방법에 따라 페이스트 충전(Paste backfill), 슬러리(수력)충전, 폐석 충전으로 구분된다. 본 논문은 광물찌꺼기로 인해 발생하는 환경적, 경제적 문제 해소 및 충전 비용절감을 위한 페이스트 충전 재료로 상동중석광산 광물찌꺼기를 이용하고자 이에 따른 특성을 평가하였다. 충전물의 물성시험을 위하여 시멘트 배합량은 3%, 4%, 5%, 6%로 설정하였고, 슬럼프(slump) 값은 170 mm, 200 mm, 230 mm, 재령일은 7일, 14일, 28일로 설정하였다. 본 연구에서 사용된 광물찌꺼기의 입도분포는 20 μm이하가 15% 이상 되어야 한다는 조건을 만족하였으며, 구성성분은 페이스트 충전물 조건 및 환경적 조건에 적합한 것으로 나타났다. 양생된 충전물의 일축압축강도는 시멘트 함량과 슬럼프 값, 재령일에 영향을 받는 것으로 나타났다. 시멘트 함량이 높고 슬럼프 값이 작을수록 강도 값은 크게 나타났으며, 시멘트 함량 6%, 슬럼프 값 170 mm, 재령 28일 때, 668 kPa로 가장 큰 값을 보였다. 충전물의 수질환경 영향을 검토한 결과 수질오염물질 배출허용기준을 만족하는 것으로 나타났다.

Backfill can be classified into paste backfill, hydraulic backfill and rock backfill according to the filling materials and the transferring methods. This paper aims at using the tailings at Sangdong tungsten Mine as a backfill material to solve the environmental and economic problems caused from the tailing dumps. It appeared that the particle size distribution and the components of the tailings sampled in this study were to be appropriate as filling material upon the physical and the environmental conditions. Cement-tailing mixture was set according to the mixing ratio of cement by 3%, 4%, 5% and 6% for property test of filling material and the slump values of the sample mixture were set to 170 mm, 200 mm and 230 mm. Curing periods were 7 days, 14 days and 28 days, respectively. The uniaxial compressive strength appeared to be affected by the content of cement, slump value and curing period. The strength was to be higher as the content of cement became higher and slump value lower. It showed the highest value of 668 kPa when the content of cement was 6%, slump value, 170mm and the curing period, 28days. After examing the seepage water quality from the filling materials, the amounts of pollutant were found to meet environmental standards.