• Elastomers and Composites
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• 제54권2호
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• pp.123-127
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• 2019

Shrink film is currently being used for plastic container lavels to avoid the use of glue. Polyethylene terephthalate (PET) bottle lavels also use shrink films in the same PET materials for easy recycling of PET bottles. An air layer is generated between the shrink film and PET bottle surface due to the bent shape of the bottle surface. This air layer can insulate external heat, as air has a relatively lower thermal conductivity. In this study, the insulation property of the air layer was examined by computer simulation. Two PET bottle models were used, one with and the other without an air layer between the PET bottle surface and lavel. The two bottle models were filled with cold liquid and exposed to room temperature for 6 h, and the temperatures of the contents were then compared. The results showed that the temperature of the contents in the bottle with the air layer was lower than that without the air layer by at least $2^{\circ}C$. This study suggests an effective lavel design of PET bottles while ensuring that the temperature of the bottle contents is maintained.

• 열처리공학회지
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• 제35권6호
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• pp.319-326
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• 2022

Direct extrusions of an aluminum 7075 alloy were carried out using 1500 ton machine with and without die cooling system. Cooling of extrusion die has been performed by the flow of liquid nitrogen and controlled by laser thermometer. Billet was 180 mm in diameter and 500 mm in length. The preheating temperatures of billet, container and die were 390℃, 400℃ and 450℃, respectively. Ram speed was kept with 1.25 mm/sec first. The change of ram speed was carried out during extrusion according to the observation of surface defects such as crack or tearing. Extrudates of 8.3 m in length, 100 mm in width and 15 mm in thickness were obtained to observe and analyze surface defects by optical microscopy and EBSD (Electron BackScattered Diffraction). In case of extrusion without die cooling cracks on the surface and tearing in the corner of extrudate occurred in the middle stage and developed in size and frequency during the late stage of extrusion. At the extrusion with die cooling the occurrence of defects could be suppressed on the most part of extrudate. EBSD micrographs showed that cracks and tearings have been resulted from the same origin. Surface defects were generated at the boundaries of grains formed by secondary recrystallization due to surface overheating during extrusion.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.793-802
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• 2024

In the framework of the European project SAMOSAFER, this numerical study focuses on some thermal aspects of the Emergency Draining Tank (EDT) located underneath the core of a Molten Salt Reactor. In case of an emergency, this tank passively receives the liquid fuel salt and is designed to ensure a subcritical state. An important requirement is that the fuel does not overheat to maintain the EDT Hastelloy container integrity. The present EDT is based upon a group of hexagonal cooling assemblies arranged in a hexagonal grid and cooled down thanks to conduction through the inert salt layer up to an air flow in charge of removing the heat. This numerical thermal study relies on a conjugated heat transfer analysis coupling a Finite Element solid thermal code (SYRTHES) and two instances of a Finite Volume CFD codes (Code_Saturne). Calculations on an initial design suggest that a simple center airpipe flow is likely to not sufficiently cool the device. Alternative solutions have been evaluated. Introduction of fins to enhance the heat transfer do not bring a noticeable improvement regarding maximum temperature reached. However, a solution in which the central pipe air flow is replaced by several cooling channels located closer to the fuel is investigated and suggests a better cooling.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2001년도 춘계학술발표대회
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• pp.76-76
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• 2001

The objective of this study was to optimize the vitrification method of in vitro produced bovine embryos. Thus, in vitro produced embryos at 8 cell, morula and blastocyst stages were vitrified on electron microscope grids (EM grids) or in open pulled straws (OPS) with EG5.5 (5.5 M ethylene glycol, 1.0 M sucrose and 10% FBS in m-DPBS medium) freezing solution and their survival rates after thawing were compared. The embryos on EM grids or in OPS were briefly exposed to EG5.5 freezing solution and plunged directly into liquid nitrogen within 30 to 35 sec. Post-thawed embryos were serially diluted in 0.5, 0.25 and 0.125 M sucrose in m-DPBS, each for 1 min, and then cultured in CRI aa medium supplemented with 10% FBS. Embryonic survival rate was assessed as re-expanded and hatched rates of those embryos after warming. The rates of re-expansion embryos did not significantly different between EM grid (8 cell: 42.10%, morula: 66.66% and blastocyst: 77.08%) and OPS (8 cell: 47.36%, morula: 61.90% and blastocyst: 83.33%) methods. In addition, the hatched rates in EM grid (8 cell: 31.57%, morula: 57.14% and blastocyst: 72.91%) were similar to those in OPS (8 cell. 34.21%, morula: 50.00% and Blastocyst: 77.08%). Interestingly, even at the same blastocyst stage, the in vitro survival of day 7 embryos (EM grid: 79.48 and OPS: 87.18%) was higher than those of day 8 embryos (EM grid: 72.10 and OPS: 82.06%). The total cell number of blastocyst developed in vitro after vitrification was examined with Hoechst 33342 staining to compare the embryo quality among different treatment groups. The total cell number of blastocyst was not significantly different between vitrified groups (EM grid: 162.4$\pm$8.0 and OPS: 158.4$\pm$7.1) and unvitrified control (168.0$\pm$5.6). These results indicate that both vitrification containers can provide the high rate of embryo survival. Moreover, the OPS container may not need a cap to protect the container from floating after immersion in L$N_2$. Therefore, this study suggest that bovine embryos can be cryopreserved easily, effectively and successfully by vitrification method using EM grid or OPS with EG5.5 freezing solution. In the future, the Pregnancy rate would be investigated after transfer of our vitrified embryos into the appropriated recipients.

• 한국항공우주학회지
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• 제44권10호
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• pp.887-894
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• 2016

고상-액상 상변화물질(PCM, Phase Change Material)을 이용한 위성부품 열제어장치를 설계 및 제작하였으며 열환경시험을 수행함으로써 온도제어 성능을 분석하였다. 설계온도에 부합하는 n-Hexadecane을 PCM으로 채용하였고, 낮은 열전도도를 보완하기 위하여 내부에 전열휜이 장착된 용기를 Al6061로 제작하였다. 위성에 장착하였을 때와 동일한 작동조건을 확보하기 위하여, 부품과 방열판 사이를 열관으로 연결하였으며 열관의 단열부가 관통하도록 PCM 열제어장치를 설치하였다. 동일한 모양과 부피의 열적완충질량(TBM, Thermal Buffer Mass)도 제작하여, 주기적인 가열-냉각 실험을 수행하였다. 실험결과 상변화 잠열에 의한 PCM의 열제어 성능을 확인할 수 있었으며, TBM에 비하여 질량과 보온히터의 소모전력을 절감할 수 있음을 확인하였다.

• 한국한의학연구원논문집
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• 제16권2호
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• pp.33-41
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• 2010

Patterns are symbolic expressions of life style or sentiment of people as a product of culture. Furthermore, it is a type of language that the shape or implication does not change much over time. Patterns shown on the Korean medical containers are related to human life and health that they are not very diverse and splendid but closed used in real life. The medical containers include the alcohol container or tea-ware in broad sense, but under this study, it would be handled only for the Korean medical containers directly used to protect human health and treatment of diseases. They would be the Medicine Mortar and Pestle that is used to grind the herbal medical ingredients, pots that hold the liquid decoction, containers to keep the medical ingredients in general conceptual use for medical purposes. The patterns inscribed are classified in animal pattern, plant pattern or alphabet pattern. Turtle, crane, ginseng, and life patterns have the contemplation to pray for long life without disease or good fortune, while plum pattern, dragon pattern and the like are used in the medical containers used mainly in royal families with the social status and dignity shown. As such, patterns have not only ornament elements but also the symbolic implication to represent long life without illness for human. It provides the basic data of medical wisdom contained in the pattern and willingness of human to protect life from illness. On the basis of such research, it would require ensuing studies to make comparison and analysis with the medical containers with the patterns in the adjacent countries in the days to come.

• 한국해양공학회지
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• 제32권4호
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• pp.272-278
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• 2018

Recently, the use of hazardous chemicals has been continuously increasing. Therefore, the international trade volume is growing and chemical accidents have increased. Nowadays, the safety awareness of the public has increased. As a result, the management and supervision of hazardous chemicals have been strengthened. However, the port policy of Korea has focused on increasing the volume of cargo through facility development. Thus, the port management of hazardous chemicals has been relatively neglected. For national economic growth and society, the port management of hazardous chemicals should be considered to efficiently ensure safety and economic growth. Therefore, this study assumed scenarios where hazardous materials were moved in a dangerous container, not only on appropriate wharfs but also in ports that were close to a big city. The BTX substances were selected among the toxic chemicals with large import and export volumes, and the risk distance and damage effects were predicted using various risk assessment programs. It is expected that this could be used to improve a port safety management system and could be utilized to determine the safety distance in case of an accident.

• 한국가스학회지
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• 제15권1호
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• pp.9-14
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• 2011

대형 디젤엔진은 주행거리가 길고 배기량이 크기 때문에 차량의 대수는 상대적으로 적지만 대기환경에 미치는 영향은 크다. 시내를 주행하는 시내버스의 경우 한일 월드컵을 계기로 CNG 버스로 전환되었다. 그러나 대형트럭과 장거리 시외버스의 경우 주행거리가 길고 CNG 충전소가 대도시의 시내버스 차고지 위주로 설치되어 있어 이용이 불가능하였다. 단열용기의 적용으로 천연가스를 압축상태가 아닌 액체 상태로 보관이 가능해져 주행거리가 긴 대형트럭이나 장거리 시외버스로의 적용이 가능해졌으며, 혼소엔진의 경우 LNG 충전이 어려운 지역에서는 디젤로 운행이 가능하다. 이와 같은 장점으로 인하여 석유 의존도를 크게 낮출 수 있어 에너지원의 다변화가 가능하며, 디젤차의 고질적인 단점으로 여겨왔던 매연 및 질소산화물뿐만 아니라 저탄소 연료를 사용함으로서 대표적인 온실가스중의 하나인 이산화탄소도 10%이상 저감할 수 있었다.

• 한국컴퓨터정보학회논문지
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• 제29권3호
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• pp.191-198
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• 2024

한국은 해상 운송에 의존하는 수출입 중심 경제 국가이며, 항만은 국가 경제 성장에 중요한 역할을 수행한다. 이러한 항만의 경쟁력을 확보하고 유지하기 위해서는 하드웨어와 소프트웨어적인 투자가 필요하지만, 정책적인 지원으로도 효과를 기대할 수 있다. 본 연구는 에너지 허브 항만인 울산항을 대상으로 항만시설 사용료 감면제도를 탐색적으로 분석하여 제도의 불합리성을 식별하고 이를 해소하기 위한 개선 방안을 제언하였다. 본 연구는 약 10년간의 울산항 물동량과 항만시설사용료 감면에 대하여 분석하였으며, 액체화물 특화 항만임에도 불구하고 컨테이너 화물에 대한 감면지원이 편중되어 있고 심지어는 통과선박이라는 사유로 이들에게 입출항료 100% 감면지원하고 있었으며 이것은 심각한 도덕적 해이를 초래할 수 있다는 점을 감면제도의 불합리 요소들로 식별하였다. 본 연구는 울산항의 항만시설 사용료 감면제도 개선 방안으로 컨테이너에 대한 지원을 친환경 활동 지원 강화, 외항통과선박에 대한 감면 요율 조정 또는 감면신청 절차 개선을 제안하였다.

• 한국식품위생안전성학회지
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• 제20권4호
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• pp.225-231
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• 2005

HPLC를 이용하여 국내유통 비타민보충용제품 16종에 대한 비타민 $B_{2}$ 저장조건별(기간, 차광유무, 온도)경시변화를 제형별로 분석하여 비타민 $B_{2}$ 함량면화를 검토하였다. 저장조건(저장기간, 차광유무, 저장온도)를 달리한 결과 비타민 $B_{2}$ 함량은 저장기간이 길어질수록 감소율이 크게 나타났으며 특히 저장을 시작한 처음 5개월 이전에는 비타민 $B_{2}$ 경시변화가 심하고 그 이후에는 점차 작은 변화를 보였다. 차광유무에 따른 경시변화를 보면 차광한 제품이 비차광한 제품보다 높은 안정성을 보였다. 온도별 안정성을 보면 냉장($4^{\circ}C$), 냉동($-9^{\circ}C$), 실온($30^{\circ}C$)순으로 감소율이 커졌으나 제형별로 영향을 많이 받지 않았다. 따라서 비타민B2는 온도보다는 빛에 더 불안정한 것으로 나타났다. 제형별로는 약간의 차이는 있으나 정제제품이 각 조건에서 타 제형보다 경시변화가 적어 안정성이 높은 것으로 나타났고 캅셀, 분발, 액상 순으로 액상제품이 가장 큰 경시변화를 보였다, 비타민보충용제품 제조시에는 유통과정 중 제형별, 저장기간, 차광유무 등 저장조건에 따른 경시변화결과를 비타민B2 함유제품의 유통기한 설정에 활용하는 것이 요망된다.