Earticle

본 연구에서는 CasNa와 TG를 혼합하여 5종의 CasNa/ TG코팅액을 제조하였고, 제조한 코팅액을 종이 표면에 코 팅하여 CasNa/TG 코팅지들을 제조하였다. 제조한 코팅지 는 TG 함량에 따라 형태학적 특성, 인장강도 및 신장율, 열 접착강도, 수증기 투과 특성에 대하여 분석하였다. CasNa/ TG 코팅지의 경우 pristine CasNa 코팅지보다 신장율, 수 증기 투과 특성이 개선됨을 확인하였다. FTIR 분석 결과, TG 함량이 증가함에 따라 피크의 세기가 변화하는 것을 확 인하였다. 또한 SEM 분석 결과, TG 함량이 증가함에 따 라 깨짐 없는 균일한 코팅층이 형성된 것을 확인하였다. 이 는 TG의 도입으로 인한 CasNa 내 화학적 구조의 변화가 CasNa 기반 코팅액과 코팅지에 영향을 미치는 것으로 판단 되며, 이로 인해 신장율, 수증기 투과 특성이 개선되는 것 으로 판단된다. CasNa 기반 코팅지의 경우 지속 가능한 포 장 소재로서 응용될 가능성이 클 것으로 예상된다. 하지만, 셀룰로오스 나노파이버, 폴리에틸렌 이민 등과 같은 첨가제 를 활용하여 CasNa의 화학적•물리적 변화에 관한 추가적인 연구와 포장 소재로 사용하기 위해 요구되는 물성인 산소 및 수분 차단 특성, 내열성 등에 대하여 추가적인 연구가 필요한것으로 판단된다.

Paper is a promising alternative to petroleum-based plastic materials for sustainable packaging applications. However, paper exhibits poor gas and water vapor barrier properties, which restrict its effective application in the packaging industry. To enhance the properties of papers, sodium caseinate (CasNa)/transglutaminase (TG) coating solutions with various TG contents were prepared and coated on the papers. The chemical and morphological structures, mechanical properties, seal strength, and water vapor barrier properties of the coated papers were thoroughly investigated. The paper properties depended significantly on the chemical and morphological structures. Pristine CasNa and CasNa/TG coating solutions were evenly coated on the paper surfaces, without any cracks. The chemical structure of the CasNa/ TG coated papers was slightly influenced by TG addition, resulting in increased elongation at break and enhanced water barrier properties. To promote the use of CasNa-coated papers in packaging applications, additional investigations must be performed to prevent gas and moisture permeation and enhance the mechanical strength of these papers via chemical reactions and introduction of organic/inorganic composites.

The goal of this study was to evaluate the effect of spent coffee grounds (SCG) biofiller on the morphological, thermal, mechanical and hydrolytic degradation characteristics of poly(lactic acid) (PLA) based biocomposites. The PLA-based biocomposite films were fabricated by using a high-viscosity kneading and hot-pressing machine. The PLA/SCG biocomposites were analyzed with SEM, DSC, TGA, UTM and hydrolytic degradation test. Aggregation in the PLA matrix is a result of increasing SCG concentrations. In the thermal properties, it was described that the cold crystallization temperature (Tcc) decreased as SCG was added to PLA. When SCG was incorporated to PLA, the degradation onset temperature (Tonset) revealed a diminish. The elastic modulus increased while tensile strength of PLA diminished as SCG was applied. Through hydrolysis analysis, the decomposition of PLA was accelerated with the addition of SCG. This research confirmed the possibility of devloping an eco-friendly packaging material with high degradability as SCG hasten the breakdown of PLA.

본 연구에서는 식량자산인 바이오매스 옥수수의 부산물 인 옥수수 피를 LLDPE에 첨가하여 바이오베이스 시트를 제조할 때 물성개선을 위한 상용화 혼합물의 적정 첨가량 을 찾고자 한다. 옥수수 피의 상용성을 높이고자 ESO와 실란 혼합물 실란을 농도별로 첨가하여 비표면적, 함수율, 입도분석 및 제조한 바이오베이스 플라스틱 시트의 물성변 화를 조사하였다. 비표면적은 1.105 m2/g, 입도는 19 μm에 서 가장 우수하였다. 시트의 충격강도, 인장강도, 신율 및 경도는 대조구에 비해 SI-1-CR은 높게 나타났으나 SI-2- CR과 SI-3-CR은 낮게 나타났다. 또 실란 혼합물 1% 처리 구에서 가장 높게 나타났다. 굴곡강도와 탄성율은 첨가량이 증가할수록 높게 나타났다. 생산 성도 대조구에 비해 큰 차 이가 없었으며, 원가의 경우도 바이오매스 부산물로 대조 구 석유계 합성 플라스틱 수지보다 50%이상 저렴하여 경 제성이 있다고 사료되었다. 이제품은 수퍼, 마트 등의 1회 용 봉투, 종량제 봉투 등에 사용될 수 있을 것이다. 이상의 결과로부터 실란 혼합물 1%를 첨가하여 바이오베이스 플라 스틱 시트를 제조하는 것이 바람직할 것으로 사료되었다.

This study investigated the characteristics for the optimal concentration of addition of the mixing solution through the corn husk pulverization and surface modification of biomass byproducts adding mixed solution between ESO and silane. And surveyed the specific surface area, water absorption, particle size and physical properties of bio- degradable plastic sheet. The specific surface area was 1.105m2/g, particle size was the highest at 19 μm. The impact strength, tensile strength, elongation and hardness of plastic sheet showed the highest at the 1% concentration among the mixing solutions. The flexural strength and modulus was high according to the increasing the mixing solution. The results above showed that it was the best the adding 1% of mixed solution after silane treatment of corn husks for its manufacture as a bio-based plastic sheet.

LDPE와 LLDPE 수지에 바이오매스 부산물을 혼합한 다 음 분해촉진제와 상용화제로 처리한 후 멀칭필름을 제조하 였다. 인장강도, 신장율, TGA, DSC를 분석하였고, 필름을 멀칭한 후 옥수수를 심고 4개월간 분해 상태를 조사하였다. 인장강도와 신장율은 UV 조사 100시간 후 20 N/cm2와 5% 로 나타났고, 200시간 후는 0 N/cm2과 거의 0%로 각각 나타났다. TGA 분석은 고분자 고유 peak변화를 확인할 수 있었으며, DSC는 결정화 온도가 조금 높아졌다. 필름의 분 해상태를 조사한 예비시험결과, 외관상태는 6주 후부터 차 이가 났으며, 12주 후에는 필름의 색상은 물론 찢어진 곳 이 여러 곳에서 볼 수 있었다. 옥수수를 식재한 다음 4개 월 후 멀칭필름의 분해상태를 조사한 결과 필름 여러 곳이 분해되어 있었고, 크게 찢겨있었다. 이상의 결과로부터 개 발 필름을 농업용 생분해성 멀칭필름으로 사용할 수 있을 것으로 사료되었다.

Mulching film was produced by LDPE and LLDPE adding biomass byproducts and MA(maleic anhydride), talc/clay/CaO/CaCO3. And also surveyed to tensile strength, elongation, TGA and DSC according to the UV irradiation time. The tensile strength and elongation showed 20 N/cm2 and 5% after UV irradiation 100 hours, and those was nearly 0 N/cm2 and 0% after 200 hours, respectively. TGA of film was showed to peak of polymer itself, and DSC was slightly higher than that of initial value. At the pilot scale test, we were able to see the differentiate of degradation between control and developed film after 12 weeks, and also torn off at several part of mulching film. The degradation of mulching film after growing corn showed similar to a pilot scale test. Above the results, the developed mulching film adding biomass will be to used for agricultural farming.

파프리카의 다양한 온도 조건(5oC, 10oC, 20oC)에서 포 장을 통한 선도 유지 효과를 검토하고자 하였다. 파프리카 는 10oC정도에서 저장·유통이 적정한 것으로 알려져 있으 나, 국내에서 유통은 상온에서 특별한 온도 관리 없이 이루 어지고 있어 선도 유지를 위한 온도관리가 요구되고 있다. 파프라카 적색과인 ‘나가노알제트(Nagano RZ)’ 등을 이용 하여 온도에 따라 나이론 필름 포장 여부에 따른 생체중량 감소, 외관 변화 등의 품질 특성을 조사하였다. 포장을 통 해서 각 온도 별로 외관에서는 포장을 한 것이 무포장보다 변화폭이 적어, 상품성 보존에 다소 효과적인 것으로 나타 났으며, 온도에 따라서는 5oC와 10oC에서는 포장을 통해 선 도 유지에 효과적으로 보였다. 20oC에서 필름 포장 여부에 관계없이 저장 중에 상품성이 빠르게 낮아지는 경향을 보 였다. 생체중량 감소 정도는 필름 포장 여부에 따라 차이가 커서 무포장이 포장한 것보다 감소 정도가 컸으며, 온도에 따라서는 20oC가 변화폭이 컸으며, 5와 10oC순으로 나타났 다. 가용성고형물과 색소, 경도 등은 저장 온도와 필름 포 장 여부에 따라 복합적으로 영향을 받아 차이를 보이는 것 으로 나타났다. 파프리카는 20oC보다 저장 온도가 낮은 5oC도나 10oC가 선도 유지에 효과적이었으며, 포장을 통해 무포장 보다 외관적 선도에 더욱더 품질을 유지할 수 있는 것으로 나타났다. 본 실험에서는 국내 유통환경에서 파프리 카를 보다 상품성을 유지할 수 있는 선도를 보존하기 위해 포장이 필요하며, 효과적인 포장 방법에 대해서는 지속적인 탐색이 필요할 것으로 보인다.

The purpose of this study was to examine the effect of packaging on quality maintenance of paprika (Capsicum annuum L. cv. Nagano RZ) stored at three different temperatures. In Korea, paprika is stored and distributed under ambient conditions. To ensure the freshness maintenance, determining optimal storage temperature is necessary. Paprika were unpacked (control) or packed with polyamide film and stored at 5oC, 10oC and 20oC for 35 days. Quality characteristics such as weight loss and appearance were examined. Paprika packed with polyamide film showed less quality changes compared to unpacked paprika under all the storage temperatures. The commercial properties tended to decrease rapidly during storage at 20oC regardless of packing. The degree of weight loss was significantly lower in packed paprika compared to unpacked paprika. It was found that soluble solids, pigments, hardness, etc. were complexly affected by storage temperature and film packaging. For paprika, the storage temperature of 5oC or 10oC was effective in maintaining freshness; paprika packed in polyamide film packing maintained greater freshness than unpacked paprika. Our results showed that, packaging is required to preserve the freshness and to improve the marketability of paprika in the domestic market. It seems that it is necessary to continuously search for an effective packaging method.

The growth of e-commerce market requires more delivery packagings, which protect goods from the damage factors on the delivery. In this study, we have analyzed the distribution environment data (vibration and impact) measured in previous study and compared with global standards (ISTA, ASTM), so that we developed the testing method for Fieldto- Lab simulation suitable to the domestic delivery. In order to verify the efficacy of this method, we took the Field-to- Lab tests for 3 packaged products (detergents set, glass tableware set, small furniture), which has been frequent breakages or damages on the actual delivery by e-commerce order, so that we could find out the test results were similar to those of the actual delivery occasions. In addition, we could perform redesign and improvement of the parcel delivery packagings for safe transportation by taking this Field-to-Lab test repeatedly. This test methods was finally proposed to be Korean industrial standard (KS), and is expected to be useful as a designing tool for the packaging optimization between protecting goods and reducing packaging waste.

Korean enoki mushrooms are exported to Southeast Asia and the United States, where there are complaints due to quality deterioration during the distribution process. In this study, we evaluated the efficacy of vacuum film packaging on quality maintenance in Korean enoki mushrooms during simulated vessel export to Vietnam using selected film, which was developed with vacuum packaging machine and oxygen absorber. We selected two MA film, one was 2-layerd 30 μm CPP film (control) and the other was 3-layered 30 μm CPP film (treatment) which is optimized film of higher gas and moisture permeability. The Korean enoki mushrooms were packaged with these two films using PAC-2000 or PAC-3000 vacuum packaging machine which was improved vacuuming of higher speed. Packed mushrooms were stored at 1oC for 2 weeks and distributed at 20oC for 2 days or 8oC for 6 days. The efficiency of the film packaging was analyzed by vacuum maintaining index, and overall the quality characteristics such as off odor, color, cap cleavage, stem elongations and sensory evaluation were evaluated during storage and distribution. Results suggest that postharvest loss of fresh enoki mushroom could be reduced by packaging mushroom with 3-layered 30 μm CPP films packaged using PAC-3000 machine during simulated vessel export to Vietnam due to vacuum maintaining. Oxygen absorber promoted off-odor at 20oC distribution temperature, and did not affect storability at 1oC storage compared to treated group without oxygen absorber treatment.

PCS needs to freely switch AC and DC to connect the battery, external AC loads and renewable energy in both directions for energy efficiency. Whenever converting happens, power loss inevitably occurs. Minimization of the power loss to save electricity and convert it for usage is a very critical function in PCS. PCS plays an important role in the ESS(Energy Storage System) but the importance of stabilizing semiconductors on PCB(Printed Circuit Board) should be empathized with a risk of failure such as a fire explosion. In this study, the temperature variation inside PCS was reviewed by cooling fan on top of PCS, and the vibration characteristics of PCS were analyzed during truck transportation for reliability of the product. In most cases, a cooling fan is mounted to control the inner temperature at the upper part of the PCS and components generating the heat placed on the internal aluminum cooling plate to apply the primary cooling and the secondary cooling system with inlet fans for the external air. Results of CFD showed slightly lack of circulating capacity but simulated temperatures were durable for components. The resonance points of PCS were various due to the complexity of components. Although they were less than 40 Hz which mostly occurs breakage, it was analyzed that the vibration displacement in the resonance frequency band was very insufficient. As a result of random-vibration simulation, the lower part was analyzed as the stress-concentrated point but no breakage was shown. The steel sheet could be stable for now, but for long-term domestic transportation, structural coupling may occur due to accumulation of fatigue strength. After the test completed, output voltage of the product had lost so that extra packaging such as bubble wrap should be considered.