Earticle

We analyzed the relationship between the main chemical properties (pH, total nitrogen content, total carbon content, and CN ratio) of sterilized medium and mushroom yields in 1 kg bag culture of Pleurotus ostreatus. The mushroom yields appeared to be highly correlated with the pH, total nitrogen content, and CN ratio, and were the highest under a total nitrogen content of 2.0–2.2% and a the CN ratio of 20–22.5. However, of the three parameters, total nitrogen content showed the highest correlation with the mushroom yield. The coefficient of determination(r2) between the total nitrogen content and the sum of the yield was 0.931, while that of the pH and CN ratio was relatively low. The nitrogen content of the medium was the most important factor in determining the yield of oyster mushrooms.

본 연구에서는 목포 근해에서 수거한 부유폐기물을 대상으로 그 조성을 조사했다. 해양 부유폐기물은 해안에 밀려오는 해안표착 폐기물과 해저로 침강한 침적폐기물로의 전환가능성이 있기 때문에 그 관리가 필요하다. 부유 폐기물의 물리적 조성에서 비닐·플라스틱류가 약 55%로 주를 이루었고 뒤이어 목재류, 섬유류, 종이류 순이었다. 나머지 항목들은 5% 미만으로 나타났다. 부유 폐기물의 화학적 성상에서 저위 발열량은 약 4,400 kcal/kg으로 나타났고, 건조기준으로 탄소의 함량은 약 70%를 차지했다. 결과적으로 부유폐기물의 물리적 조성이 비교적 단순하며, 에너지 함량이 높아 연료로써 활 용 가치가 높았다.

Physical and chemical characteristics of marine floating debris in the sea near Mokpo were investigated in this study. Marine floating debris on the surface of the sea has a possibility to be deposited in the coasts as coast debris or undergone deposition into the seabed through debris sinking, because of these reasons, management of marine floating debris is essential. From the results of physical composition of marine floating debris, vinyl and plastics accounted for 55%, followed by wood, textiles and papers. The rest of the marine floating debris is less than 5%. With regards to the chemical property of marine floating debris, the lower heating value is shown to be about 4,400 kcal/kg and the content of carbon (C) with dry basis made up more than seventy percent. The result of the experiments confirmed that marine floating debris showed the simple physical composition and a possibility to use a new source of renewable energy.

본 연구는 2014년부터 2022년까지 국내에서 발생한 화학사고의 원인 및 동향을 체계적으로 분석하였다. 특히, 인명피해, 환경피해, 그리고 재산피해를 종합적으로 고려하여, 각 사고유형의 상대적 위험성과 사고 동향을 규명하고자 하였다. 상대적 위험성 분석을 통해 사고유형별 상대적 위험성과 가장 위험한 사고유형을 도출하였으며, LDA 토픽 모델링과 네트워크 분석을 활용하여 가장 위험한 사고유형으로 도출된 화재사고에 대해 사고동향을 분석하였다. 분석 결과, 인명피해 측면에서 가장 위험한 사고유형은 폭발사고이며, 환경과 재산에 미치는 영향이 큰 사고 유형은 화재사고로 분석되었다. LDA 토픽 모델링 결과, 화학물질 화재사고는 크게 4가지 주요 토픽으로 분류되었다. LDA 토픽 모델링과 네트워크 분석을 활용한 방법을 통해 화학사고의 복잡한 원인과 패턴을 분석하는 것이 가능하며, 활용된 방법을 통해 화학사고의 예방과 대응 전략을 효과적으로 수립할 수 있을 것으로 판단된다.

This study analyzed the causes and trends of chemical accidents that occurred in Korea from 2014 to 2022. In particular, by comprehensively considering human casualties, environmental damage, and property damage, the relative risks and accident trends of each type of accident were identified. Utilizing the relative risk, the most dangerous accident type for each type of accident were derived. And, LDA topic modeling and network analysis were used to analyze accident trends for fire accidents identified as the most dangerous accident types. Results showed that the most dangerous accident type in terms of human casualties was explosion accidents, and the type of accident with a large impact on the environment and property was analyzed as fire accidents. As a result of LDA topic modeling, chemical fire accidents were broadly classified into four major topics. It is possible to analyze the complex causes and patterns of chemical accidents through methods using LDA topic modeling and network analysis, and it is possible to effectively establish prevention and response strategies for chemical accidents through the methods used.

This study was carried out to investigate the cause of leaf discoloration occurring frequently in paddy cultivation. Chemical property of soil and inorganic nutrient component of leaf were analyzed on abnormal fields of 7 regions where leaf discoloration occurred severely and normal fields of 7 regions among ginseng garden. The pH of abnormal fields was strong acidic condition (pH 5.51) compare to normal fields of slightly acid condition (pH 6.42). Calcium and magnesium content in abnormal fields were lower distinctly than that of normal fields, while EC, organic matter, phosphate, and potassium content showed not distinct difference between abnormal and normal fields. Whereas calcium and magnesium content were distinctly high in normal fields, both of potassium and iron content of ginseng leaf were distinctly high in abnormal fields. In particular, iron content of abnormal fields was more 1.94 times in soil, and 3.03 times in leaf than that of normal fields. In soil chemical property, there were significant negative correlation between leaf discoloration ratio and soil pH, and there were also significant positive correlation between leaf discoloration ratio and iron content. In ginseng leaf, there were highly significant negative correlation between leaf discoloration ratio and calcium content, and there were also highly significant positive correlation between leaf discoloration ratio and iron content.

In this study, in an effort to distinguish the morphological characteristics and chemical composition of dust, samples were collected indoors (receiving room) and outdoors (roads, front yard, and backyard) using the 3M EVM-7 series for 24 h. Scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) analysis provided visual evidence of the dust in terms of the shape and chemical composition of the particles. The area fraction and size range were also measured using image analyzer software. The morphology, chemical composition, average size, and size distribution of the dust were analyzed. In the case of outdoor dust, the mean dust particle size was measured as 4.13 and 3.63 m in the road and front yard, respectively. These outdoor dusts in road and front yard had a mean size range from 2.55 to 4.13 ?m. The size distribution results showed that outdoor dust has a relatively larger particle size (>2 m) than indoor dust. In case of indoor dust, approximately 40 % of dust particles had sizes less than 2 ?m. Regarding morphology, indoor dust had a relatively simple shape. However, the outdoor dust was composed of various elements, and its form was complicated. The outdoor dust was composed of lightweight metal elements, such as aluminum, silicon, calcium, and magnesium, due to the seasonal effect of the spring. In addition, the road dust and, in the case of dust from the front yard adjacent to the road, the carbon and sulfur content originating from vehicle fuel were observed to be relatively high.

본 연구는 트레이싱지와 크로스지를 주요 연구대상으로 삼고, 대조군으로 와트만 여과지를 선정하여 촉진 내후성 시험을 통해 인공 열화가 종이의 물리⋅화학적 특성에 미치는 영향을 분석하 였다. 실험 결과, 순수 셀룰로오스 섬유로 구성된 와트만 여과지는 산성화 외에는 열화에 의한 변화가 거의 없었으며, 이는 셀룰로오스 기반 종이의 열화 기준을 제시하는 데 유용하였다. 트레이싱지는 변색과 강도 저하가 뚜렷하게 나타났으며, 이는 투명성을 향상시키기 위해 첨가된 가소성 물질 등의 열화 때문으로 추정된다. 크로스지의 경우, 폴리에스터 섬유에 전분으로 추정되는 다당류가 사이징 처리된 구조를 가지고 있었으며, 열화가 진행됨에 따라 산성화와 강도 저하가 두드러졌다. 이러한 변화는 첨가된 다당류의 열화에 기인한 것으로 판단된다. 본 연구 결과는 트레이싱지와 크로스지의 열화 특성을 이해하는 데 중요한 기초 자료를 제공하며, 향후 다양한 도면에 사용된 재질에 대한 열화 연구가 이루어진다면 실제 도면의 열화 메커니즘 파악과 장기적 보존 방안 수립에 중요한 기초 자료가 될 것으로 기대된다.

Herein, the effects of accelerated aging on the physical and chemical properties of tracing paper and cloth paper were studied via accelerated weathering tests, using Whatman filter paper as a control. Results indicated that the Whatman filter paper, which comprises pure cellulose fibers, exhibited minimal changes due to deterioration besides acidification, making it a valuable benchmark for studies on cellulose-based paper degradation. Tracing paper exhibited considerable discoloration and strength loss with aging, likely due to the degradation of the plasticizers added to enhance its transparency. Cloth paper, which comprises polyester fibers treated with a polysaccharide (assumed to be starch), exhibited considerable acidification and strength loss with aging progression, which can be attributed to the breakdown of the added polysaccharides. These results provide essential insights for understanding the degradation characteristics of tracing and cloth papers. Moreover, further research on the materials used in various drawings will offer critical insights into the mechanisms of document deterioration and contribute to the development of long-term preservation strategies.

본 연구에서는 PBAT의 가교 개질을 위해 DCP를 도입 하였고 화학발포제인 ADC를 PBAT에 분산시킨 후 압축성형 공정으로 발포제의 분해를 통해 셀을 형성하여 시트 형태의 PBAT 발포체를 제작하였다. FT-IR 분석을 통해 DCP의 분해를 확인하였으며 DCP 함량에 따른 PBAT의 용융 흐름 지수를 비교하여 가교로 인한 용융 점도의 향상 을 확인할 수 있었다. DSC 분석을 통해 열적 특성을 비교 한 결과 Tc의 변화를 확인할 수 있었고 이를 통해 DCP 첨가로 인한 가교 반응의 결과를 확인할 수 있었다. TGA 분석 결과를 통해 DCP의 첨가가 열 안정성의 유의미한 차 이를 야기시키지 않는 것을 확인하였다. 발포 시트의 DCP 함량 별 기계적 물성은 유의미한 차이를 보이지 않았으나 PB_D3에서 다소 낮은 인장강도를 보였으며 PB_D3의 큰 셀 사이즈로 인해 응력 전달에 부정적으로 작용하여 인장 강도 및 연신율이 감소하였을 것으로 판단하였다. DCP 함 량 증가에 따라 발포 셀의 개수는 감소하였으나 평균 셀 사이즈는 증가하였고 가장 큰 PB_D3의 평균 셀 사이즈로 인해 발포 시트의 밀도가 가장 낮게 나타났다. 반면 이러한 큰 셀의 사이즈와 낮은 밀도는 열전도도를 감소시키는 요 인으로 작용하여 PB_D3 발포 시트의 경우 최대 0.066W/ mk 까지 감소시킬 수 있었기에, 단열 특성을 지닌 생분해 성 발포 시트로의 활용에 대한 가능성을 확인할 수 있었다.

Poly (butylene adipate-co-terephthalate) (PBAT) is one of the representative biodegradable polymers with high ductility and processability to replace petroleum-based polymers. Many investigations have been conducted to broaden the applications of PBAT in a variety of industries, including the food packaging, agricultural mulching film, and logistics and distribution fields. Foaming process is widely known technique to generate the cell structure within the polymer matrix, offering the insulation and light weight properties. However, there was no commercially feasible foam product based on biodegradable polymers, especially PBAT, and maintaining a proper melt viscosity of the polymer would be a key parameter for the foaming process. In this study, chemical foaming agent and cross-linking agent were introduced to PBAT, and a compression molding process was applied to prepare a foam sheet. The correlation between cell morphological structures and mechanical and physical properties was evaluated. It was found that PBAT with foam structures effectively reduced the density and thermal conductivity, allowing them to be suitable for applications such as insulation and lightweight packaging or cushion materials.

The various ingredients have been used to improve the qualities and prolong the preservation in cosmetics. The preservative is considered as one of the most important ingredients to keep the cosmetics for long and also safely as it has anti-septic and anti-fungal functions. However, several previous studies have demonstrated that there are some potential factors causing allergies, and some issues related with side effects of cosmetic preservatives have been reported through various media. On the other hand, the government which has implemented detailed policies on the preservative uses in cosmetics still has insisted the safety of cosmetic preservative uses with some organizations. These lead to a great interest on the safety of preservatives in cosmetics. Therefore, this paper has researched and analyzed the official legislations and regulations, chemical properties and previous studies on cosmetic preservatives to give recent and correct information. Even though the government has enhanced the ingredients labeling performed with safety and quality managements on cosmetics lately, some studies still have demonstrated that preservatives can causes side effects. As an alternative to these preservatives, natural preservatives have had a huge attention lately. However, they are still required to get researched further in terms of safety. Therefore, the main purpose of this paper is to provide an updated overview on the occurrence of preservatives in cosmetics for the safe cosmetic uses to people.

The Cottonseed oil methyl ester (COME) was prepared using an alkali - catalyzed trans esterification reaction, and its chemical composition and cold flow properties (CFP) were studied. Two approaches, viz. blending with petrodiesel and treating with cold flow improver (CFI) were used to improve the CFP of COME. The results showed that COME was mainly composed of fatty acid methyl esters (FAMEs): C14:0–C22:0, C16:1–C20:1, C18:2 and C18:3–C20:3. The mass fractions of saturated and unsaturated FAMEs were 27.69% and 71.65%, respectively. The cold filter plugging point (CFPP) and kinematic viscosity (KV) at 40 °C of COME are -1 °C and 4.63 mm2/s respectively. Blending with -10 petrodiesel (-10PD) and 0 petrodiesel (0PD) can decrease the CFPP of COME/-10PD (B30-B40) and COME/0PD (B40-B50) -12 and -8 °C respectively. With the increase in petrodiesel content, the KV at 40 °C of blending oil decreased, and viscosity-temperature characteristics of blending oil were improved. When used Flow Fit (≤3vol.%), the CFPPs were reduce from COME/- 10PD B5, B7, B10, B20, B50 and COME -8, -8, -9, -11, -11 and -1 °C to -28, -27, -26, -25, -16 and -5 °C respectively; COME/0PD -3, -3, -4, -5, -8 and -1 °C to - 26, -25, -24, -24, -16 and -5 °C respectively.

Barley Yellow Mosaic Virus(BaYMV) is responsible for ane of the most improtant disease in malting Barley in Korea. It is transcitted by soil borne fungus, Polymyza graminis To estimate the occurrence pattern of BaYMV by the physio-chemical property of soil collected from farmer's sield, this study was conducted. The rate of didsease occurrence to BaYMV investigated at 19 spots of 10th regions. The sample soil was collected by 20 pots among an ifected field and analyzed th soil characters in 2002. The rate of disease occurrence to BaYMV was about 79%,60%,65% in Sacheon, Kosung and Hadong areas, respectively, which is malting Barley growing regions but Pohang, Yeongduk, Euesung, Gunwee, which are growing Covered Barley doesn't infected BaYMV. The tested of RT-PCR was showed that the BaYMV, BMMV.SBWMV. were identified in Milyang but the others regions was infected only to BaYMV. The physio-chemical property of soil collected from infected soil show various range such as pH(4.98~8.05), EC(0.44~2.7%),OM(1.61~6.85), P2O5958~519), K(0.22~1.82), Ca(2.3~9.7), Mg(0.5~2.6), Na(0.14~0.43) The correlation coefficient between physio-chemical property fo the infected soil and infection rate shows significant to pH at 5% level. Although OM and Ca were high scores, it doesn't significant at 5% but it need to be more study in future.

The scientific information between microbial activities and chemical properties of reclaimed tidal soil is not enough to apply for reclamation projects. This study was conducted to investigate the relation between chemical properties and microbial activities of reclaimed tidal lands located at western coastal area (25 samples from Nampo, Ewon, Sukmoon and Shihwa sites). Most of the reclaimed soils showed chemical characteristics as salinity soil except Nampo site. The major component influenced the salinity of reclaimed soil was identified as a sodium from the relationship between EC and exchangeable cation. With an increase in EC of soil, the population of mesophilic bacteria decreases whereas halotolerant and halophilic bacteria increases. The population of mesophilic bacteria increased with an increase in both organic matter and dehydrogenase activity. However, the population of halotolerant and halophilic bacteria decreased with an increase in organic matter. Based on the relation between chemical property and microbial activity of reclaimed tidal soil, electrical conductivity and organic matter as chemical properties of soil, population of mesophilic bacteria, halotolerant and halophilic bacteria and dehydrogenase activity as microbial activities could be the major parameters for reclamation process.

This study was carried out to investigate the addition of water-soluble isoflavone into milk by means of microencapsulation technique. The yield of microencapsulation, sensory attributes, and capsule stability of water-soluble isoflavone microcapsules in milk were measured. Coating materials used was polyglycerol monostearate (PGMS), and core material was water-soluble isoflavone. The encapsulation yield of water-soluble isoflavone with PGMS was 67.2% when the ratio of coating material to core material was 15 : 1. The rate of water-soluble isoflavone release from capsules was 18, 19, and 25% when stored at 4,20, and $30^{\circ}C$ for 12 days in milk, respectively. In sensory evaluation, beany flavor and color of microencapsuled water-soluble isoflavone added milk were significantly different from uncapsuled water-soluble isoflavone added milk, however, bitterness was not significantly different. In vitro study, micro-capsules of water-soluble isoflavone in simulated gastric fluid with the range of 3 to 6 pHs were released 3.0∼15.0%, however, the capsules in simulated intestinal fluid with pH 7 were released 95.7% for 40 min incubation time. In conclusion, this study provided that PGMS as coating materials was suitable for the microencapsulation of water-soluble isoflavone, and the capsule containing milk was almost not affected with sensory attribute.

Some important properties of the liquid crystal molecules containing fluoro-isothiocyanated molecules have been studied using quantum chemical calculations and the results were correlated with respect to the structure of the molecules. Dielectric anisotropy, birefringence have been predicted for several unknown structures. The Maier-Meier, Vuks equation were used for the dielectric anisotropy and birefringence calculation. The results obtained by empirical approximation showed a good agreement with experiment ones.

This study is a continuation of the previous experimental analysis and is mostly focused on handsheet strength properties. Four completely different fibers, which were Hw-BKP, Sw-BKP, white ledger, and OCC, were selected to investigate the effect of mechanical pre-treatment by Hobart mixer on handsheet strength properties. After equal time mechanical pre-treatment, the fibers were refined with laboratory valley beater for 10, 20 and 30 minutes, and handsheets were prepared from the fibers for physical strength comparison. Handsheets from SW-BKP and OCC showed 5-30% increase of breaking length, burst index, tear index, and compression index while handsheets from HW-BKP and white ledger no Increase except tear index. In Hobart mixer pre-treatment, HW-BKP and white ledger fibers were easily attached to the wall of the mixer bowl and mechanical action was not effectively applied. The fiber length of Hw-BKP and white ledger were 0.837mm and 1.591 mm, respectively, while SW-BKP and OCC were 2.744 mn and 2.033 mm, respectively, in weight weighted length. The effective mechanical pre-treatment seems to be related to the fiber length. Tear indexes of the pre-treated furnish were much higher than no pre-treatment at the same breaking length level.

In the previous experiment, it was found that OCC pre-treatment with Hobat mixer at 20-25% consistency for 3 hrs or more followed by the application of the equal refining time, caused the increase of tensile strength, burst strength, compressive strength and tear resistance, compared to the no pre-treated. Four completely different fibers, which were Hw-BKP, Sw-BKP, White ledger, and OCC were selected for this experiment to investigate the effect of mechanical pre-treatment process on different fibers. From the experiment, it was found that the mechanical pre-treatment did not decrease fiber length at all, but decreased freeness, compared to the no pre-treated, when the same refining time was applied WRVs of the pre-treated fibers were higher than the no pre-treated at the same freeness level. It was speculated that the mechanical pre-treatment induced only hydrophilic nature of fibers without damaging fiber length by delaminating fiber walls. The fiber surface area and the physical strength differences of handsheets will be discussed in the next publication.

In this paper, Cu-coated graphite sintered body for weight reduction and high thermal conductivity was fabricated using achemical reaction process and pulsed current activated sintering process. First, 4 g of coarsening graphite powders, which wastreated using an activation and wetting process, was added to an aqueous solution of copper (Cu) sulfate; also, 35 g of zinc(Zn) powders was added as a transposition solvent to the aqueous solution, and stirred for 1 h for a transposition reaction. After the addition of the fabricated powders mixture to a 75 wt.% DI water : 10 wt.% H3PO4 : 10 wt.% H2SO4: 5 wt.%mixture, tartaric acid was added to the aqueous solution to produce a passivating oxide film, followed by drying for 24 h. Thelow-intensity oxide peak of the XRD pattern of the fabricated powders was due to the suitable Zn powder content. The Cucoatedgraphite powder was used to carry out direction control for high thermal conductivity. Cu-coated graphite sinteredbodies were fabricated using a pulsed current activated sintering (PCAS) process. The Cu-graphite sintered bodies weresintered at 850 oC with heating rate steps of 20 and 30 oC/min, respectively. The Cu-coated graphite powders and compactswere evaluated using FE-SEM, EDS, XRD, TEM, particle analysis, Archimedes’ method, electronic conductivity, thermalcoefficient, and thermal conductivity.

In this paper, we synthesize ZnO wire on Si substrate by catalyst-free thermal chemical vapor deposition (CVD). Each ZnO wire is grew up at different condition such as temperature and O2 flow rate. The Young's modulus of individual ZnO wires were estimated using quasi-static and dynamic measurements, as well as resonance frequency measurements. Using this system, current-voltage characteristics of each ZnO wire structure fabricated on a trench were measured. A new concept of electromechanical device structure combined with the piezoelectric effect of ZnO will be suggested in the end of this paper.