Earticle

본 연구에서는 전자레인지 조리 시 발생하는 포장 내부 의 수증기를 스스로 방출할 수 있는 PLA 기반 스마트 복 합 필름을 제조하였다. 제조된 복합필름의 전자레인지 조리 가 가능한 HMR 제품의 포장재로써 적용가능성을 평가하 기 위해 DSC, UTM, GTR 및 전자레인지 모의 적용 평 가를 통해 열적 특성, 기계적 특성, 온도 구간별 기체 투과 도 및 전자레인지 적용성을 평가하였다. 복합필름의 열적 특성을 확인한 결과, PLA와 PEG의 강한 화학적 상호작용 을 확인하였고 본 연구에서 기대한 전자레인지 조리 온도 내에서 PEG가 용융되는 것을 확인하였다. 또한, 제조된 복 합필름은 PEG의 첨가로 인해 인장강도는 감소하였지만 연 신율이 증가하였고, nanoclay의 함량이 증가함에 따라 감소 된 인장강도가 일부 회복한 것을 확인하였다. 또한, 기체 투과도의 경우 PEG의 Tm1 이상인 65°C 부터 PEG가 용 융되면서 투과도가 비약적으로 증가한 것을 확인하였다. 전 자레인지 모의 적용 평가를 통해 pure PLA는 내부 수증기 를 방출하지 못하고 그 압력을 버티지 못해 폭발한 것에 비해, 복합필름의 경우 전자레인지 수증기 발생 온도에서 그 형태를 유지하며 효과적으로 내부 수증기를 자가방출한 것을 확인하였다. 이러한 결과를 바탕으로 본 연구에서 제 조한 스마트 복합필름은 포장재로써 향후 전자레인지 조리 HMR식품 포장재로써 적용될 수 있다.

The demands for Home Meal Replacement (HMR) products are continuously increasing owing to the convenience of instant food and online food delivery. Ready-to-heat (RTH) products have received massive attention in the HMR industry because these products can be easily warmed using a microwave oven. However, the conventional microwave packaging should be opened before microwave heating to prevent bursting or food loss owing to the steam-pressure build-up inside the package. Open packaging might lead to non-uniform food heating and cross-contamination. Therefore, packaging materials that are able to release steam without opening are of interest to the HMR industry. In this study, polylactic acid(PLA)/polyethylene glycol(PEG)/nanoclay composite films were manufactured using an extrusion method as packaging materials with a smart steam-releasing function. The introduction of PEG to the PLA imparted a steam selfreleasing feature to the composite films owing to the morphology change of composite films during microwave heating. Further, PEG increased the ductility of PLA, which in turn prevented bursting caused due to the steam-pressure build-up. The uniform dispersion of nanoclay obtained by a twin-screw extrusion led to stronger mechanical properties. Therefore, the smart composite films developed here can be applied as microwave packaging materials with a self-releasing function.

최근 지구온난화 심화와 환경재난 등으로 석유유래 플라 스틱의 분해에 대한 관심이 높아지고 있다. 플라스틱의 분 해를 촉진하는 산화촉진제로 ferric ion(Fe2+)을 농도별로 첨가하여 필름을 제조하였다. 대조군으로 LLDPE필름과 산화 촉진제를 농도별로 첨가한 필름에 UV를 시간별로 조사하 여 인장강도, 신장율과 분자량변화를 조사하였다. 수지에 ferric ion 첨가량이 많아질수록 물성저하가 컸으며, 분자량 변화도 큰 것으로 나타났다. 인장강도는 대조군에 비해 산 화촉진제 첨가필름이 조사시간 100시간 후 부터는 현저하 게 저하되었으며, 이러한 현상은 신장율에서도 비슷한 것으 로 나타났다. 분자량은 산화촉진제 첨가에 따른 결과로 UV 조사 50시간 후 63.6%, 100시간 후에는 73.8% 분자량이 감소한 것으로 나타났다. 이상의 결과에서 플라스틱 필름에 산화촉진제인 ferric ion(Fe2+)을 첨가함에 따라서 필름의 강 도와 분자량이 저하되는 결과와 김 등17) 등의 보고를 바탕 으로 필름의 분자량이 저하되면 그만큼 필름이 분해되고 있 다고 판단할 수 있을 것으로 사료되었다.

If petroleum- derived plastic like a bio-based plastic was degradation, awareness like a global warming and environmental disasters will be decreased. Plastic film was produced by adding ferric ions according to concentration by using a pro-oxidant in polyolefin resin. Changes in tensile strength, elongation, and molecular weight were evaluated according to the UV irradiation time. Increasing the amount of ferric ions resulted in more significant declines of physical properties, and also resulted in greater changes in molecular weight. After 100 hours of UV irradiation, tensile strength declined significantly in the film containing pro-oxidant as compared to the control. A similar effect was also observed in terms of elongation. The film containing pro-oxidant showed a 73.8% decrease in molecular weight after 100 hours of UV irradiation. The appropriate use of pro-oxidant can not only degrade plastic film but also control the time of degradation at the petroleum- derived plastic films. Further studies are necessary to investigate the conditions of plastic film degradation.

화장품용 펌프는 복합재질의 내부 부품들과 복잡한 구조 로 인하여 소비자들이 재질별로 분리 배출할 수 없는 구조 를 이루고 있으며, 특히 금속 스프링을 사용하고 있어 재활 용률이 현저히 떨어졌다. 하지만 최근 국내·외에서 환경오 염으로 인한 다양한 규제 및 소비자의 인식 변화로 친환경 적인 제품의 수요도 급격히 증가하고 있으며, 이에 따라 화 장품 업계에서도 재활용률을 높이기 위해 다양한 시도가 진 행되고 있다. 또한 아직 국내·외 플라스틱 화장품 용기의 재활용률이 20% 내외로 낮은 상황에서 친환경 화장품 용 기 세계시장 선점과 국내 포장산업 활성화를 위해서는 기 술적 차별화와 동시에 선진기업 수준의 품질 성능을 갖춘 화장품용 고성능 펌프의 개발이 필요하다. 따라서, 본 연구 에서는 단일재질(PP)로 구성된 0.2 ml 고성능 펌프를 개발 하였으며, 실험을 통해 감압 시 내용물의 누수와 용기 변형 이 없으며, 누름강도 14.8~17.5N, 토출량 편차 2.3~8.8%, 초기 공타 4회로 기존 금속재 스프링을 사용한 복합소재 펌프와 대등한 수준의 품질 성능을 확인할 수 있었다. 또한, 단일소재를 사용하였기 때문에, 향후 국내·외 친환경 화장 품 용기 시장 점유율 확대와 함께 플라스틱 재활용률 향상 에 기여할 것으로 기대된다.

Cosmetic packing materials tend to be difficult to recycle when discarded due to the cosmetic industry’s pursuit of aesthetics, functionality, and high value-added design. Pump packaging, which is widely used for the good preservation and discharge of cosmetics contents, is difficult to be separated and recycled because of a metal spring, which is in charge of pump resilience. In this study, a polypropylene spring was developed to replace the existing metal spring to improve the recyclability of the pump packaging for cosmetics, and was uni-materialized by applying to the cosmetic packing materials with 0.2 ml of discharge amount. In addition, performance test was conducted to verify the equivalence with the existing metal spring pumps as grounds for the commercialization of metal-free uni material pump packaging. The decompression leak test showed no leakage and displayed 14.8~17.5 N of pressing strength, 2.3~8.8 % of deviation in dispensing volume, and 4 occasions of pumping for initial discharge.

중금속은 첨가제 성분이나 오염으로 인해 식품용 플라스 틱 기구 및 용기, 포장 제품에 유입되어 식품을 통해 인체 로 노출될 수 있다. 따라서 본 연구에서는 독성을 가진 7종 의 중금속(납, 카드뮴, 니켈, 크롬, 안티몬, 구리, 망간)을 선 정하고 국내 유통되는 16재질 137개 제품들에서의 이행량 을 파악하여 위해도 평가를 수행하였다. 대상 검체들은 4% 초산을 식품모사용매(70oC, 30분)로 적용하여 이행시험을 수행하였다. 동시분석을 위해 유도결합플라즈마 질량분석법 (ICP-MS)을 적용했으며 선형성, 검출 한계(LOD), 정량 한 계(LOQ), 회수율, 정밀도를 측정하고 확장불확도를 산출하 여 정량결과의 신뢰성을 확보하였다. 모니터링 결과, 전체 적으로 불검출 (ND) ~ 8.76 ± 11.87 μg/L의 수준으로 검출되 었으며, 대부분이 평균 1 μg/L 미만의 미량으로 확인되었다. 또한 안티몬이 PET 재질에서 다른 재질들에 비해 통계적 으로 유의하게 높게(p < 0.05) 측정되었다. 마지막으로 위해 도를 평가한 결과, 국내 유통되는 제품들의 중금속들은 인 체안전기준 대비 모두 안전한 수준으로 유지되고 있는 것을 확인하였다.

Heavy metals can be intentionally or unintentionally introduced into plastic food utensils, containers, and packaging (PFUCP) as additives or contaminants, which can be ingested with food by humans. Here, seven-heavy metals (lead, cadmium, nickel, chromium, antimony, copper, and manganese) with toxicity concerns were selected, and risk assessment was done by establishing their migration from 137 PFUCP products made of 16 materials distributed in Korea. Migration of heavy metals was examined by applying 4% acetic acid as a food simulant (70oC, 30 minutes) to the PFUCP products. Inductively coupled plasma mass spectrometry (ICP-MS) was employed for the analysis of migrated heavy metals, and the reliability of quantitative results was confirmed by checking linearity, LOD, LOQ, recovery, precision, and expanded uncertainty. As a result of monitoring, heavy metals were detected at a level of non-detection to 8.76 ± 11.87 μg/L and most of the heavy metals investigated were only detected at trace amounts of less than 1 μg/ L on average. However, antimony migrated from PET products was significantly higher than other groups. Risk assessment revealed that all the heavy metals investigated were safe with a margin of exposure above 311. Collectively, we demonstrated that heavy metals migrated from PFUCP products distributed in Korea appear to be within the safe range.

본 연구에서는 패키징 인쇄를 위한 병렬 오프셋 인쇄 공 정의 스케줄링 문제를 다루었다. 문제에 대해 두 부분으로 구분하여 접근하였고, 각각 할당 문제와 차량 경로 문제를 적용하여 수리적으로 모형화 하였다. 스케줄링 모형의 현장 적용성은 실험을 통해 검토하였다. 실제 데이터로 구성된 작은 규모의 문제에서는 수리모형으로도 실용적인 시간 내 에 최적해를 도출할 수 있었고 이와 비교하여 메타 휴리스 틱의 성능을 확인하였다. 기업이 보유한 데이터를 바탕으로 문제 규모를 확장한 실험에서는, 수리모형의 최적해와 비교 하여 메타 휴리스틱이 해의 품질을 보장하면서 시간적 효 율성을 확보할 수 있었다. 본 연구는 수작업 위주의 기존 방식은 주체(작업자)에 따 라 스케줄링의 결과에 불확실성이 존재하는 문제에 주목하 였다. 이러한 불확실성은 전체 생산 비용의 증가를 가져오 기 때문에 이를 개선할 수 있도록 실용적인 시간 내에 일 관된 결과를 제공하는 스케줄링 모형을 제시하였다. 제시한 모형은 단일 라인과 병렬 라인 모두에 적용되어 작업자의 경험에 의존하던 기존의 방식을 개선하는데 도움이 될 것 으로 판단되며, 시간 함수의 정의를 통해 다른 요인들을 반 영하는 연구로의 확장이 가능하다는 의의를 갖는다. 향후 주문의 납기, 복수의 라인에서 동일 주문 인쇄, 동 일하지 않은 라인의 인쇄 용량, 조색 난이도 등을 고려하는 연구로의 확장을 통해 패키징 인쇄 분야의 스마트 생산 시 스템 도입에 기여할 수 있을 것으로 기대된다.

With the growth of the packaging industry, demand on the packaging printing comes in various forms. Customers’ orders are diversifying and the standards for quality are increasing. Offset printing is mainly used in the packaging printing since it is easy to print in large quantities. However, productivity of the offset printing decreases when printing various order. This is because it takes time to change colors for each printing unit. Therefore, scheduling that minimizes the color replacement time and shortens the overall makespan is required. By the existing manual method based on workers’ experience or intuition, scheduling results may vary for workers and this uncertainty increase the production cost. In this study, we propose an automated scheduling method of parallel offset printing process for packaging printing. We decompose the original problem into assigning and sequencing orders, and ink arrangement for printing problems. Vehicle routing problem and assignment problem are applied to each part. Mixed integer programming is used to model the problem mathematically. But it needs a lot of computational time to solve as the size of the problem grows. So guided local search algorithm is used to solve the problem. Through actual data experiments, we reviewed our method’s applicability and role in the field.

Sustainable energy supplies without the recharging and replacement of charge storage device have become increasingly important. Among various energy harvesters, the triboelectric nanogenerator (TENG) has attracted considerable attention due to its high instantaneous output power, broad selection of available materials, eco-friendly and inexpensive fabrication process, and various working modes customized for target applications. The TENG harvests electrical energy from wasted mechanical energy in the ambient environment. TENG devices are very likely to be used in next-generation renewable energy and energy harvesting. TENG devices have the advantage of being able to manufacture very simple power devices. In this experiment, various organic dielectrics and inorganic dielectrics were used to improve the open voltage of TENG, Among the various organic dielectrics, Teflon-based FEP, which has the highest electron affinity, showed the highest open voltage and Al electrode was fabricated on Teflon substrate by sputtering deposition process. And AAO (Anodized Aluminum Oxide) nanostructures were applied to maximize the specific surface area of the TENG device. The power generation of TENG within the acceleration level (0.25, 0.5, 1.0, 1.5 and 2 G) and the frequency range (5-120 Hz) of the domestic transport environment was up to 4 V.

Expanded polystyrene (EPS) is the most commonly used fresh food refrigeration insulation in Korea and Europe. Moreover, as the use of disposable packaging materials has increased significantly along with non-face-to-face delivery services since the COVID-19 crisis, social issues related to waste disposal are also being raised. Therefore, in this study, the life cycle of EPS boxes for fresh food is focused on the factors that have a large difference between incineration and landfill including recycling in Europe and Korea in the disposal process after use, and raw materials and energy in the manufacturing process, which account for a large portion of the environmental impact value. We tried to compare the environmental impact of evaluation. Overall, the raw material production stage, box manufacturing stage, and packaging stage have similar processes in Europe and Korea, but unlike Europe, Korea, which lacks landfills and incineration facilities, has focused on expanding the recycling rate. It was necessary to do an environmental impact assessment. Data affecting the environment were derived based on 2019 and 2020 data for Korea and 2017 and 2020 data for Europe. In order to predict the future environmental impact assessment, assumptions about the disposal rate in 2025 and 2030 were introduced and evaluated. As a result of this study, it was found that the raw material production stage of EPS boxes, which have similar processes in both Korea and Europe, has the greatest effect on the global warming effect of Korean EPS boxes. However, Korea, which has a relatively high recycling rate in the disposal process compared to incineration and landfill, showed better environmental performance than Europe in most impact indicators except freshwater eutrophication. In particular, Korea has increased the overall recycling rate compared to Europe by replacing various recyclable materials such as building materials and sundries with XPS (extruded polystyrene) recycled materials. In conclusion, it was found that increasing the recycling rate rather than incinerating and landfilling EPS boxes for fresh food in the domestic EPS industry has relatively less environmental load compared to Europe.

Air distribution occupies an important position in the smart unit load container design process for agricultural products. Inner air may be uncomfortable because of its temperature, speed, direction, and volume flow rate. It doesn't matter how efficient the ventilation equipment is if the air is not distributed well. The main aim of this study was to design the inlet and outlet fan locations of smart unit load container for agricultural products. A numerical study was performed on the effects of the location of inlet air and outlet air in relation to the container cooling sources on air distribution and thermal comfort. A concept of combining inner container cooling sources with the exhaust outlet was employed in this investigation. Also, in this research, the developed CFD (Computational Fluid Dynamics) models were thoroughly validated. This system was adopted for use in container spaces, where the exhaust outlet was located. In this study, the location of the inlet was derived through CFD for a container with a size of 1,100×1,100×1,700 mm, and it was derived that the inlet was located at the center of the lower part of the container for efficient air flow. It was efficient to position the outlet through the air inlet in the center of the lower part of the container at the top of the same side.

저온에서 신선육을 보관 저장하는 용기의 기체조성을 고 CO2/저O2 농도로 자동적으로 제어하는 용기 시스템을 제작 하고, 0°C에서 21일간 돼지고기 삼겹살을 담아 저장하면서 품질보전의 측면에서 진공 포장과 함기 대조구 조건과 비교 하였다. CO2 주입 시간 프로그램에 의하여 CO2 농도는 47~ 60%, O2 농도는 7~10%로 유지될 수 있었고, 이는 호기적 세균 증식과 pH 증가의 억제의 효과와 함께 관능적 품질유 지에 기여하였다. 진공포장은 함기 대조구에 비하여 낮은 미 생물 성장과 pH 증가를 보여주었으나 높은 drip 손실의 단 점을 보였다. 전체적 품질보존의 측면에서 고안된 고CO2 치 환 용기는 육류의 품질유지에 효과적이며, 육류의 종류와 특 성에 맞게 기체 농도 조건을 변경하여 활용범위를 확장할 수 있을 것이다.

Container system automatically controlled in its atmosphere of high CO2/low O2 was devised to contain and store pork belly meat at chilled temperature. The meat in the container system was compared in the quality preservation at 0°C for 21 days to that in air-filled container and vacuum package. The container atmosphere could be controlled to be of 47~60% CO2 and 7~10% O2 through time-controlled intermittent CO2 injection. The controlled atmosphere in the developed system was effective in suppressing pH change and aerobic bacterial growth contributing to sensory quality preservation. Compared to control of air-filled container, vacuum packaging showed lower microbial growth and slower pH change on the meat but with high drip loss. The devised container system to keep high CO2 and mildly low O2 concentrations is effective in the meat quality preservation on overall, and may be extended to a variety of meat products with possible modification tuned for product requirements.

파프리카 저장 및 유통 전 처리와 포장방법이 저장성 및 미생물 제어에 미치는 영향에 대해 알아보고자 수행되었다. 이산화염소 가스 3, 6, 12시간과 저온 플라즈마 가스 1, 3, 6시간 처리 후 골판지 박스로 포장하여 8 ± 1oC 챔버에서 7 일간 저장 하였을 때, 이산화염소 12시간 처리와 플라즈마 6 시간 처리가 대장균과 곰팡이 발현을 낮추는 것으로 나타났 다. 이에 무처리 대조구와 이산화염소 12시간, 플라즈마 6시 간 처리한 후 골판지 박스 포장과 MAP 처리를 하여 8 ± 1oC 챔버에서 20일간 저장하였다. 저장 중 생체중 감소는 MAP 처리구가 1% 미만의 수치를 보였고, 외관상 품질은 MAP 처리구가 저장 종료일까지 상품성 한계점 이상이었다. 필름 내 산소, 이산화탄소, 에틸렌 농도는 처리구간의 차이 가 나타나지 않았다. 경도의 경우 이산화염소 처리구가 낮았 고, 색도를 나타낸 Hunter a* 값은 MAP 처리구에서 증가하 였다. 이취는 MAP 처리구에서 측정되었지만 매우 낮았다. 파프리카 과경의 곰팡이 발생률은 이산화염소 처리 박스 포 장 처리구가 가장 빠르고 높게 발생하였고, 이산화염소 처리 MAP 처리구가 가장 낮았다. 저장 종료일 과육의 총 세균수 는 플라즈마 처리 박스 포장 처리구, 대장균수는 이산화염소 처리 MAP 처리구, 곰팡이는 이산화염소 처리 박스 포장 처 리구가 가장 낮았다. 이상의 결과를 종합해보면, 파프리카 저 장 중 미생물 억제를 위해 포장 방법과 관계없이 저장 전 플라즈마를 6시간 처리하는 것이 적합하다고 판단된다.

This study was conducted to investigate the effect of packaging methods and sterilization treatment on storability and microbial control in paprika fruits. When treated with chlorine dioxide gas for 3, 6, and 12 hours and cold plasma gas for 1, 3, and 6 hours, and then packed in a carton box and stored in a 8 ± 1oC chamber for 7 days, chlorine dioxide treated 12 hours and plasma treated 6 hours was prevented the development of E·coli and YM(yeast and mold). Accordingly, the control was treated with chlorine dioxide for 12 hours and plasma for 6 hours, packed using a carton box and 40,000 cc·m-2·day-1·atm-1 OTR film (MAP), and stored in a 8 ± 1oC chamber for 20 days. Fresh weight loss rate during storage was less than 1% in the MAP treatments, and the visual quality of the MAP treatments was above the marketability limit until the end of storage. There was no difference in the contents of oxygen, carbon dioxide, and ethylene in the film. In the case of firmness, the chlorine dioxide treatments was low, and the Hunter a* value, which showed chromaticity, was highest in the Plasma 6h MAP treatment. Off-odor was investigated in the MAP treatments, but it was very low. The rate of mold growth on the fruit stalk of paprika was the fastest and highest in the chlorine dioxide treated box packaging treatments, and the lowest in the chlorine dioxide treated MAP treatments at the end of storage. The aerobic count in the pulp on the storage end date was the lowest in the plasma treated box packaging treatments, the lowest number of E·coli in the chlorine dioxide treated MAP treatments, and the lowest yeast & mold in the chlorine dioxide treated box packaging treatments. As a result, for the inhibition of microorganisms during paprika storage, it is considered appropriate to treat plasma for 6 hours before storage regardless of the packaging method.

상추의 양액재배 별 생육과 수확 후 저장 특성에 미치는 영향을 규명하고자 하였다. ‘청치마’ 상추를 이용하여, 무동 력 수경재배 장치를 이용한 피트모스 배지경과 순수 담액 수경 재배의 생육을 비교하였고, 수확 후 상추의 생체중량 변화, SPAD, 외관 등의 저장 특성을 검토하였다. 상추는 무동력수경재배의 배지경과 담액수경 재배 방법 간에 생육 후의 초장을 제외한 생체중, 엽수, SPAD, 수분함량, C/N율 에서 차이가 없었다. 상추 재배 시 무동력 수경재배 방식을 통한 양액재배는 기존의 담액수경재배와 비교하여 생육에 무리가 없는 것으로 나타났다. 양액재배 방법에 따른 상추 를 수확 후 저장 중 생체중량 감소나 외관 지수가 뚜렷한 차이를 보이지 않았다. 다만 엽록소 함량과 관계 있는 SPAD에서 저장기간이 지속됨에 따라 배지경 재배가 다소 높은 것으로 나타났다. 상추와 같은 작물이 재배적 이상이 없는 호조건에서 재배되는 경우, 수확 전 재배 방법에 따라 서 수확 후 저장에 크게 영향을 미치지 않는 것으로 판단 된다.

The research was aimed to improve pre-harvest methods to maintain marketability in postharvest leaf lettuce. In this study, the effect of hydroponics on the growth and post-harvest storage characteristics of ‘Chongchima’ lettuce grown in peat mass medium hydroponic system using a non-powered culture device or deep water culture (DWC) was evaluated. There was no difference in fresh weight, leaf number, SPAD, moisture content, and C/N ratio between peat moss growing medium hydroponic and DWC methods except plant height. It was found that lettuce cultivation by a nonpowered hydroponics method is easier than the existing DWC. The quality parameters, such as fresh weight loss, SPAD value, and general appearance of lettuce were investigated after harvest. There was no significant difference in fresh weight loss and general appearance during storage of lettuce by the hydroponics methods. However, with the increased storage time of SPAD, which is related to chlorophyll content, was slightly higher in peat moss medium hydroponic was than DWC. When crops such as lettuce are grown under favorable conditions without any agronomic abnormalities, it is suggested that post-harvest storage is not significantly affected by peat moss growing medium hydroponic and DWC.

Onions are a significant crop in Korea, and cultivation is increasing every year along with high demand. Onions are planted in the fall and mainly harvested in June, the rainy season, therefore, physiological changes in onion bulbs during long-term storage might have happened. Onions are stored in cold room and at adequate relative humidity to avoid quality loss. In this study, bio-yield stress and weight loss were measured as the quality parameters of net packaged onions during 10 weeks of storage, and the storage environmental conditions are monitored using sensor networks systems. Quality estimation of net packaged onion during storage was performed using the storage environmental condition data through machine learning approaches. Among the suggested estimation models, support vector regression method showed the best accuracy for the quality estimation of net packaged onions.