• 설비공학논문집
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• 제23권5호
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• pp.327-333
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• 2011

In the present work, a new freeze protection method has been proposed for a natural circulation system of solar water heater. Though electrothermal wire is popularly used for the purpose, there are freezing troubles by wire cut-off and shortage of excessive electric power consumption. In the experimental device, hot water in storage tank was used to heat the outlet pipe from the tank if the pipe surface temperature falls lower than a set point. The cold water pipe to the storage tank was installed to directly contact the hot water pipe surface temperature rose by transferred heat.

• 한국가스학회지
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• 제7권4호
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• pp.36-43
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• 2003

본 논문에서는 LNG 냉열 에너지를 활용한 지역 냉방 시스템 가능성에 대해 고찰하고자 한다. 액상의 LNG는 기상의 가스로 변환하는 과정에서 많은 냉열 에너지를 발생한다. 최근에 빙축열을 이용한 건물의 냉방 시스템 구축과 심층수를 이용한 지역 냉방 시스템이 도심지의 기존 사무실 건물이나 대규모 건물의 냉방장치로 도입되고 있는 상황이다. LNG의 냉열 에너지는 기존의 냉매에 의존한 개별 냉방 시스템을 대체하는 새로운 냉열 에너지 공정으로 쾌적한 공간을 제공하는 천연의 대규모 냉각매체로 재사용될 수 있다. 버려지는 냉열 에너지는 낮은 코스트로 운영될 수 있는 중요한 청정 에너지원이기 때문에 냉방 시스템으로 개발되면, 기존의 에어콘 시스템에 견주어 볼 때 공기중에 유해한 오염원의 발생과 환경적으로 유해한 냉매 방출을 대폭적으로 줄일 수 있는 우수한 냉방 시스템이 될 것이다. 따라서, 본 연구에서는 냉열 에너지를 활용한 지역 냉방 시스템에 대한 환경 친화적 기본적 설계 개념, 여러 가지 냉방 시스템 성능에 대한 유익한 기반적 정보를 제공하고자 한다.

• 설비공학논문집
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• 제6권4호
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• pp.406-416
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• 1994

In this study the reactor design procedure and method of solid-solid-gas chemical heat pump system using STELF technology were investigated. For manufacturing IMPEX block which is the kernel of reactor, proper salt pair should be selected, and equilibrium temperature drop and COP should be examined for selected salt pair. Moreover, apparent density, residual porosity, and graphite ratio should be calculated to give minimum block volume and mass, and maximum energy density without causing heat and mass transfer problems. Since heat exchange area can be changed with operating condition, reactor diameter, length, and stainless steel thickness should be decided for desired specifications. These procedure and method were applied to the case study of 6kW cold production and 8 hours storage capacity reactor.

• Journal of Advanced Marine Engineering and Technology
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• 제21권1호
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• pp.26-36
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• 1997

Recently, the new refrigerating system, using non - fluorinated hydrocarbon refrigerants has to be developed for the agricultural fields. One of that kinds of systems is the cooling system using the water vapor and vacuum, in which the water evaporate at the low temperature under vacuum and absorb the large amount of the latent heat. If vapor with large amount of latent heat is removed from the system, the system is cooled accordingly. The characteristics of cooling under the vacuum was observed and measured using experimental apparatus, which is consisted of vacuum chamber, the ejectors, the pumps and the measurement apparatus. As the results of experiments, we know that the evaporation in the vacuum occurs vigorously when the materials to be cooled has more amounts of heat before cooling, and by which effects the materials can be cooled. The cooling vacuum system is more efficient than other methods when the agricultural products is chilled or dried.

• 한국식품위생안전성학회지
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• 제26권1호
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• pp.31-35
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• 2011

본 연구에서는 최근 새롭게 출현한 식중독 세균인 Arcobacter butzleri 국내 분리 균주를 고온과 냉장 및 냉동 조건에 노출시킨 후 생존성을 조사하였다. 열처리를 한 경우 $50^{\circ}C$ 5분 이후부터 유의적으로 감소하였으며, $60^{\circ}C$와 $70^{\circ}C$ 열처리 조건에서는 생존성이 급격히 감소하였다. $4^{\circ}C$와 $-70^{\circ}C$ 온도에 저장할 경우 유의적인 생존성 감소가 없었으나, $-20^{\circ}C$ 냉동조건에서는 A. butzleri의 생존성이 유의적으로 감소하였다. 특히 장내용물에서 분리된 A. butzleri는 계육에서 분리된 균주보다 열처리에 저항하는 특정이 있었다. 따라서 고온처리 및 냉동 저장 등은 A. butzleri를 효과적으로 제어할 수 있는 기술개발에 활용할 수 있을 것으로 판단된다.

• 한국축산식품학회지
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• 제40권3호
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• pp.415-425
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• 2020

It is believed that two main proteolytic systems are involved in the tenderization of meat: the cathepsins and the calpains. Many researchers consider the calpain system to be the major contributor to meat tenderness during post-mortem storage. However, the role and activity of cathepsins during post-mortem storage or low temperature meat processing is unclear, particularly for the tough meat cuts like brisket. Thus, the study was designed to investigate the effects of cold (refrigerated and frozen) storage and sous vide processing on the activities of cathepsin B, H, and L in beef brisket. There were no significant changes in pH and cathepsin H activity throughout the 18 d of storage at both temperatures. However, an increase in cathepsin B activity was observed during the first 4 d at both storage temperatures, but subsequently the activity remained unchanged. Cathepsins B and L were found to be more heat stable at sous vide temperatures (50℃ for 24 h, 55℃ for 5 h and at 60℃ and 70℃ for 1 h) compared to cathepsin H. Cathepsin B+L activity was found to increase after sous vide cooking at 50℃ for 1 h but decreased to about 47% relative to the uncooked control after 24 h of cooking. These results suggest that cathepsins B and L may contribute to the improved meat tenderness usually seen in sous vide cooked brisket meat.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.250-255
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• 2003

TMA clathrate that is used as PCM of low temperature thermal storage system in this research creates hydrate crystallization at higher temperature then pure water, and its application is expected as PCM because of comparatively big latent heat without phase separation phenomenon. Acetone, Ethylen Glycol, and Ethanol is used as additive and evaluated experimentally for the purpose of the improvement in subcooling of TMA clathrate. In view of the results so far achieved subcooling is improved, the running time of the refrigerator is reduced. Thus the results are expected to use for the increase of coefficient of performance of low temperature thermal storage system in the building.

• 펄프종이기술
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• 제46권4호
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• pp.93-100
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• 2014

The packaging with environment-friendly materials become more important issue since the concern for the environment and the disposal of waste such as the packaging materials has increased. Although the paper based packaging such as corrugated box are widely used as a typical environment-friendly packaging stuff, the heat insulation properties of paper packaging did not get many attention. In this study, the heat insulation properties of paper were deeply evaluated to improve the functional properties as packaging material of the cold storage goods. The simple device for evaluating the heat insulation of paper product was developed. Subsequently, the changes in the heat insulation depending on the paper structure and the addition of the inorganic fillers were investigated by using the instrument. The higher basis weight and the less beating time resulted in the bulkier structure and the less efficiency of heat transfer. The addition of the perlite powder as a filler resulted in the great increase in the heat insulation, although the addition of the calcium carbonate decreased the heat insulation potential of paper.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.642-650
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• 2016

One of the most feasible solution for reducing the excessive energy consumption and carbon dioxide emission is usage of more efficient fuel such as hydrogen. As is well known, there are three viable technologies for storing hydrogen fuel: compressed gas, metal hydride absorption, and cryogenic liquid. In these technologies, the storage for liquid hydrogen has better energy density by weight than other storage methods. However, the cryogenic liquid storage has a significant disadvantage of boiling losses. That is, high performance of thermal insulation systems must be studied for reducing the boiling losses. This paper presents an experimental study on the effective thermal conductivities of the composite layered insulation with aerogel blankets($Cryogel^{(R)}$ Z and $Pyrogel^{(R)}$ XT-E) and Multi-layer insulation(MLI). The aerogel blankets are known as high porous materials and the good insulators within a soft vacuum range($10^{-3}{\sim}1$ Torr). Also, MLI is known as the best insulator within a high vacuum range(<$10^{-6}{\sim}10^{-3}$ Torr). A vertical axial cryogenic experimental apparatus was designed to investigate the thermal performance of the composite layered insulators under cryogenic conditions as well as consist of a cold mass tank, a heat absorber, annular vacuum space, and an insulators space. The composite insulators were laminated in the insulator space that height was 50 mm. In this study, the effective thermal conductivities of the materials were evaluated by measuring boil-off rate of liquid nitrogen and liquid argon in the cold mass tank.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.617-626
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• 1993

Energy saving is a very important subject for research workers nowadays. While most people are concerning with the modern methods, the authors investigated this problem from another angle- the chinese traditional methods of energy saving. The tunnel with technique and its combination with computer simulation and fuzzy compressive judgement methods are discussed. Earth heat green house, marsh gas, solar energy underground storage system, storing of nature cold sources, have been introduced in this paper.