• 설비공학논문집
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• 제12권12호
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• pp.1098-1125
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• 2000

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 1998 and 1999 has been done. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environment. The conclusions are as follows. 1) A review of the recent studies on fluid flow, turbomachinery and pipe-network shows that many experimental investigations are conducted in applications of impingement jets. Researches on turbulent flows, pipe flows, pipe-networks are focused on analyses of practical systems and prediction of system performance. The results of noise reduction in the turbomachinery are also reported. 2) A review of the recent studies on heat transfer analysis and heat exchanger shows that there were many papers on the channel flow with the application to the design of heat exchanger in the heat transfer analysis. Various experimental and numerical papers on heat exchanger were also published, however, there were few papers available for the analysis of whole system including heat exchanger. 3) A review of the recent studies on heat pump system have focused on the multi-type system and the heat pump cycle to utilize treated sewage as the heat source. The defrosting and the frosting behaviors in the fin-tube heat exchanger is experimentally examined by several authors. Several papers on the ice storage cooling system are presented to show the dynamic simulation program and optimal operation conditions. The study on the micro heat pipes for the cooling of high power electronic components is carried out to examine the characteristics of heat and mass transfer processed. In addition to these, new type of separate thermosyphon is studied experimentally. 4) The recent studies on refrigeration/air conditioning system have focused on the system performance and efficiency for new alternative refrigerants. New systems operating with natural refrigerants are drawing lots of attention. In addition to these, evaporation and condensation heat transfer characteristics of traditional and new refrigerants are investigated for plain tubes and also for microfin tubes. Capillary tubes and orifice are main topics of research as expansion devices and studies on thermophysical properties of new refrigerants and refrigerant/oil mixtures are widely carried out. 5) A review of the recent studies on absorption cooling system shows that numerous experimental and analytical studies on the improvement of absorber performance have been presented. Dynamic analysis of compressor have been performed to understand its vibration characteristics. However research works on tow-phase flow and heat transfer, which could be encountered in the refrigeration system and various phase-change heat exchanger, were seemed to be insufficient. 6) A review of recent studies on duct system shows that the methods for circuit analysis, and flow balancing have been presented. Researches on ventilation are focused on the measurement of ventilation efficiency, and variation of ventilation efficiency with ventilation methods by numerous experimental and numerical studies. Furthermore, many studies have been conducted in real building in order to estimate indoor thermal environments. Many research works to get some information for cooling tower design have been performed but are insufficient. 7) A review on the recent studies on architectural thermal environment and building mechanical systems design shows that thermal comfort analysis is sitting environment, thermal performance analysis of Korean traditional building structures., and evaluation of building environmental load have been performed. However research works to improve the performance of mechanical system design and construction technology were seemed to be insufficient.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1503-1506
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• 2009

Bubble jet loop heat pipe is a newly devised variation of heat pipe in which heat is effectively transported by the latent heat of evaporation and condensation as well as the heat capacity of circulating working fluid. The circulatory and oscillating motion of the working fluid becomes possible by the motion of bubble jet which is generated at a narrow circular gap. These bubbles are condensed at the condensing section. Bubble jet loop heat pipe makes it possible to carry heat long distances upward and horizontal directions. Because Its structure is a very simple and a low cost, it is available for the floor heating, vinyl house heating, the defrosting of heat pump system and home refrigerator.

• 대한기계학회논문집B
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• 제35권2호
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• pp.161-168
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• 2011

HVAC(Heating, Ventilating, Air Conditioning) 시스템은 승객실 내부의 열환경을 제어하여 쾌적성을 향상시키거나 전면 유리창에 생성된 성에를 제거하여 운전자의 가시영역을 확보하는 등 차량의 성능과 관련된 매우 중요한 기능을 담당한다. 본 연구에서는 CFX 를 사용하여 HVAC 시스템의 기능 중 제상 덕트의 성능과 관련된 수치해석적 연구를 수행하였다. 제상덕트의 해석결과, 출구에서의 유량배분특성 및 유동구조는 일반적인 설계주안점에 부합된 양호한 결과를 얻었다. 외부온도 $-18^{\circ}C$ 하에서 물의 잠열인 $3.37{\times}10^5$[J/kg]을 고려한 상변화 과정을 수치적으로 모사하기 위하여 열용량법을 사용하였고, 시간에 따른 제상패턴 해석을 위해 얼음과 유리의 고체도메인에 대한 추가적인 격자 생성 작업이 필요하였다. 유동해석 결과, 전면유리 근처의 유동구조, 유적선, 온도장 해석결과는 본 연구에서 수행한 제상덕트 모델이 우수한 성능으로 제상기능을 수행할 수 있음을 보였으며, 수치해석적 결과는 실험적 결과와 비교하여 제상패턴이 잘 일치함을 확인하였다. 또한 전면유리 상의 4 개의 지점에서 얻어진 온도, 물분율, 엔탈피의 시간에 따른 변화를 통해 상변화 과정을 정량적으로 파악하였다.

• 한국식품위생안전성학회지
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• 제22권1호
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• pp.63-75
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• 2007

전라북도내 사업체, 병원, 학교, 사회복지시설 등 집단급식소 설치 신고를 한 집단급식소 98개 업소를 대상으로 설문조사를 실시하여 집단급식소의 위생관리 실태에 대하여 조사하였다. 식기 기구 및 용품의 소독 방법은 식기, 수저, 행주의 경우 열탕 소독이, 주방기기, 냉장고, 냉동고, 도마, 칼의 경우 소독제 방법이 많이 사용되었다. 위생복(34.4%), 위생모(34.4%), 냉장고(32.6%), 냉동고(31.8%)의 순으로 소독을 하지 않는 경우가 많았다. 위생교육 횟수는 월 1회가 56.1%로 가장 많았고, 월 2-3회 12.2%, 주 1회 11.3%순 이었다. 집단급식소의 일지 작성율은 해동일지(73.8%), 창고 및 화장실 점검일지(60.5%), 기구 등의 세척 및 살균 일지(54.5%),등의 순으로 많이 작성되었고, 조리장 위생관리 점검표(9.5%), 조리 종사자 위생점검 일지(10.8%), 위생교육 일지(8.4%) 등은 작성율이 낮았다. HACCP 제조 도입시 급식시설과 설비의 부족(54.1%)과 HACCP 제도에 대한 이해 부족(17.3%)이 주요 장애 요인이었다. 주방기기 및 기구 취급, 개인위생, 급 배수 시설 및 쓰레기 처리, 건물의 구조, 배치 및 시설관리에 대한 위생관리는 잘 이루어지고 있지 않았다. 집단급식소의 영양사들은 종사자의 개인위생과 급 배수 시설 및 쓰레기 처리에 대한 위생관리에 대해서는 잘 인식하고 있었으나 주방기기 및 기구 취급과 건물의 배치 및 시설의 위생 관리에 대해서는 인식이 부족하였다. 따라서 발생률이 계속 증가하는 식중독의 발생을 감소시키기 위해서는 위생관리 체계의 도입과 위생관리에 대한 영양사 인식의 전환이 필요하였다.

• 설비공학논문집
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• 제16권12호
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• pp.1234-1268
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• 2004

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2002 and 2003 has been carried out. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment/design. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation in diverse facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat transfer, humidity was also interesting to promote comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing research topics. Well developed CFD technologies were widely applied for analysis and design of various facilities and their systems. (2) Heat transfer characteristics of enhanced finned tube heat exchangers and heat sinks were extensively investigated. Experimental studies on the boiling heat transfer, vortex generators, fluidized bed heat exchangers, and frosting and defrosting characteristics were also conducted. In addition, the numerical simulations on various heat exchangers were performed and reported to show heat transfer characteristics and performance of the heat exchanger. (3) A review of the recent studies shows that the performance analysis of heat pump have been made by various simulations and experiments. Progresses have been made specifically on the multi-type heat pump systems and other heat pump systems in which exhaust energy is utilized. The performance characteristics of heat pipe have been studied numerically and experimentally, which proves the validity of the developed simulation programs. The effect of various factors on the heat pipe performance has also been examined. Studies of the ice storage system have been focused on the operational characteristics of the system and on the basics of thermal storage materials. Researches into the phase change have been carried out steadily. Several papers deal with the cycle analysis of a few thermodynamic systems which are very useful in the field of air-conditioning and refrigeration. (4) Recent studies on refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement when new alternative refrigerants are applied. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and new alternative refrigerants including natural refrigerants. Efficiency of various compressors and performance of new expansion devices are also dealt with for better design of refrigeration/air conditioning system. In addition to the studies related with thermophysical properties of refrigerant mixtures, studies on new refrigerants are also carried out. It should be noted that the researches on two-phase flow are constantly carried out. (5) A review of the recent studies on absorption refrigeration system indicates that heat and mass transfer enhancement is the key factor in improving the system performance. Various experiments have been carried out and diverse simulation models have been presented. Study on the small scale absorption refrigeration system draws a new attention. Cooling tower was also the research object in the respect of enhancement its efficiency, and performance analysis and optimization was carried out. (6) Based on a review of recent studies on indoor thermal environment and building service systems, it is noticed that research issues have mainly focused on several innovative systems such as personal environmental modules, air-barrier type perimeterless system with UFAC, radiant floor cooling system, etc. New approaches are highlighted for improving indoor environmental conditions and minimizing energy consumption, various activities of building energy management and cost-benefit analysis for economic evaluation.

• 설비공학논문집
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• 제19권1호
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• pp.94-131
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• 2007

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2004 and 2005 has been done. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation of facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat, humidity was also interesting for comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing topics. Well developed CFD and flow visualization(PIV, PTV and LDV methods) technologies were widely applied for developing facilities and their systems. (2) The research trends of the previous two yews are surveyed as groups of natural convection, forced convection, electronic cooling, heat transfer enhancement, frosting and defrosting, thermal properties, etc. New research topics introduced include natural convection heat transfer enhancement using nanofluid, supercritical cooling performance or oil miscibility of $CO_2$, enthalpy heat exchanger for heat recovery, heat transfer enhancement in a plate heat exchanger using fluid resonance. (3) The literature for the last two years($2004{\sim}2005$) is reviewed in the areas of heat pump, ice and water storage, cycle analysis and reused energy including geothermal, solar and unused energy). The research on cycle analysis and experiments for $CO_2$ was extensively carried out to replace the Ozone depleting and global warming refrigerants such as HFC and HCFC refrigerants. From the year of 2005, the Gas Engine Heat Pump(GHP) has been paid attention from the viewpoint of the gas cooling application. The heat pipe was focused on the performance improvement by the parametric analysis and the heat recovery applications. The storage systems were studied on the performance enhancement of the storage tank and cost analysis for heating and cooling applications. In the area of unused energy, the hybrid systems were extensively introduced and the life cycle cost analysis(LCCA) for the unused energy systems was also intensively carried out. (4) Recent studies of various refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and of alternative refrigerants including carbon dioxide. Efficiency of various compressors and expansion devices are also dealt with for better modeling and, in particular, performance improvement. Thermoelectric module and cooling systems are analyzed theoretically and experimentally. (5) According to the review of recent studies on ventilation systems, an appropriate ventilation systems including machenical and natural are required to satisfied the level of IAQ. Also, an recent studies on air-conditioning and absorption refrigeration systems, it has mainly focused on distribution and dehumidification of indoor air to improve the performance were carried out. (6) Based on a review of recent studies on indoor environment and building service systems, it is noticed that research issues have mainly focused on optimal thermal comfort, improvement of indoor air Quality and many innovative systems such as air-barrier type perimeter-less system with UFAC, radiant floor heating and cooling system and etc. New approaches are highlighted for improving indoor environmental condition as well as minimizing energy consumption, various activities of building control and operation strategy and energy performance analysis for economic evaluation.

• 한국식품위생안전성학회지
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• 제26권4호
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• pp.308-314
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• 2011

대형할인매장에서의 냉장 냉동판매대의 설정온도와 판매중인 냉장 냉동 가공식품류들의 표면온도를 측정하여 비교 분석한 결과 냉장판매대 설정온도 평균은 $3.5{\pm}1.8^{\circ}C$로, 최소 $0^{\circ}C$에서 최대 $7^{\circ}C$까지 분포하며, 냉장식품의 평균 표면온도는 $10.7{\pm}2.9^{\circ}C$로, 최소 $4.6^{\circ}C$와 최대 $18.4^{\circ}C$까지 분포하는 것으로 나타났다. 전체적으로 냉장식품의 표면온도가 설정온도보다 평균적으로 $7.2^{\circ}C$ 높으며, 총 냉장식품의 53%는 표면온도가 $10^{\circ}C$이상으로 나타났으며, 47%만이 $10^{\circ}C$이하로 나타났다. 특히, 야채 및 과일류 등은 온도 차이가 낮았으나 냉장음료류는 온도 차이가 가장 높은 식품군으로 나타났다. 냉동판매대의 경우 설정온도 평균은 $-20.7{\pm}1^{\circ}C$이며, 냉동식품 평균 표면온도는 $-15.4{\pm}5^{\circ}C$로, 최소 $-28^{\circ}C$에서 최대 $-4.6^{\circ}C$(제상중 제품 포함)까지 분포하는 것으로 나타났다. 냉동육류($-13.8^{\circ}C$), 냉동가공식품($-15.9^{\circ}C$), 아이스크림류($-16.8^{\circ}C$) 순으로 낮은 표면 온도를 가지고 있었으며, 실제 냉동식품의 32.3%만이 $-18^{\circ}C$이하의 온도를 나타내는 것으로 조사되었다. 결론적으로 냉장 냉동식품 모두 식품자체의 표면온도가 냉장 냉동 판매대에서 설정된 온도보다 높았으며, 냉장 냉동보관 식품별 온도편차가 다양한 것으로 나타나 유통매장에서 냉장 냉동식품 온도관리에 대한 새로운 관리체계가 마련되어야 할 것이다.