• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1789-1794
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• 2004

The present study investigates flow characteristics in an optical disc drive. Detailed knowledge of the flow characteristics is essential to analyze flow-induced noise and vibration, forced convection and flow friction loss. The ODD used in the personal computer is used for the experiment and rotating velocity of disc is under the 4500 rpm. Time-resolved velocity components and velocity spectrum are obtained using the laser Doppler anemometry (LDA). The results show that the front holes reduce now-induced noise and the position of pickup body affects flow near the window. In addition, il is possible for cooling of heat sources in an optical disc drive through measuring the flow fields under the tray.

• 기본간호학회지
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• 제23권2호
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• pp.184-193
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• 2016

Purpose: The aims of the current study were to evaluate the effects of superficial cold and heat after spine surgery on pain, satisfaction with pain control and comfort level, and to identify subjective responses and adverse effects. Methods: A prospective, single-blind, randomized controlled trial was utilized. The intervention group (n=36) received superficial cooling until the wound drain was removed and thereafter followed by superficial heating until discharge, while the control group (n=34) received only superficial cooling until wound drain was removed. Data were collected from August 4 to November 11 2014. Results: There was significant difference in pain according to time within groups (F=71.87, p<.001). However, we found no difference in pain between groups. The intervention group reported higher patient satisfaction with pain control (4 vs 3, z=-2.83, p=.005) and higher comfort level (5 vs 4, z=-4.12, p<.001) than the control group. Conclusion: Results indicate that sequential application of superficial cold and heat is a useful method in clinical practice for management of pain after spine surgery.

• 한국식품조리과학회지
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• 제24권5호
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• pp.652-664
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• 2008

In this study, a Hazard Analysis Critical Control Point (HACCP) plan was developed for the sanitary mass production of commercial Korean rice cake products (Gaepidduk, Injulmi, and Julpyon). The microbiological properties of manufacturing flow were evaluated in order to develop the HACCP Plan. The moisture contents of the rice cakes ranged between 36.2${\sim}$55.3%, whereas the water activity of all samples ranged between 0.954${\sim}$1.0. Microorganisms testing was conducted during various phases of the product flow of Korean rice cake preparation, and included assessments of food equipment, work environment, and cooking employees on a small scale. During the manufacture of Injulmi, Julpyon and Gaepidduk, CCPs were purchasing & storage, steaming and cooling, molding, and holding in the A and B manufactories. At the critical limit of CCPs, storage was conducted below at $5^{\circ}C$ in soybean powder, oil, and paste with redbeans. The steaming process was conducted above at $99^{\circ}C$ for 40 min. Cooling and holding processes were conducted for 2 hours below at $15^{\circ}C$. The molding process included sanitary education for foodhandlers and training for operators. Thus, certain prerequisite programs had to be implemented prior to the implementation of the HACCP system. High levels of bacterial contamination were detected in the aprons worn to work by some employees. Additionally, periodic sanitary education for foodhandlers and training for operators or managers was required. Cross contamination by materials was expected at the place where materials were processed or stored.

• 한국생산제조학회지
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• 제8권1호
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• pp.89-99
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• 1999

The automatic design of shell & tube type oil cooler can be used in real industrial environments. Since the automatic design system is intended to be used in small companies, it is designed to be operated well under environments of CAD package in the personal computer. It has adopted GUI in design system, and has employed DCl language. Design parameters to be considered in the design stage of shell and tube type oil cooler are type of oil cooler, outer diameter, thickness, length of tube, tube arrangement, tube pitch, flow rate, inlet and outlet temperature, physical properties, premissive pressure loss on both sides, type of baffle plate, baffle plate cutting ratio, clearance between baffle plate outer diameter and shell inner diameter and clearance between baffle plate holes. As a result, the automatic design system of shell & tube type oil cooler is constructed by the environment of CAD software using LISP. We have built database of design data for various kinds of shell & tube type oil coolers. The automatic design system have been assessed and compared with existing specification of design. Good agreement with Handbook of heat exchanger and design dta of real industrial environments has been found.

• 대한기계학회논문집B
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• 제29권2호
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• pp.224-231
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• 2005

The present study investigates flow characteristics in an optical disc drive (ODD). Detailed knowledge of the flow characteristics is essential to analyze flow-induced noise and vibration, forced convection and flow friction loss. The ODD used in a personal computer is used for the experiment and rotating velocity of disc is under the 4500 rpm. Time-resolved velocity component and velocity spectrum are obtained using the laser Doppler anemometry (LDA), and the flow patterns induced by rotating disc in the ODD are calculated by a commercial finite volume method at the same time. The results show that the front holes reduce flow-induced noise and the position of pickup body only affects flow near the window. Furthermore, it is possible for cooling of heat sources in the drive through measuring the flow fields under the tray. In addition, the numerical results are well matched up to the experimental results, therefore, the validation of the numerical results can be achieved. From the validation of numerical results, it is possible to predict the flow characteristics of the region where it is unable to conduct the experiment.

• Safety and Health at Work
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• 제8권4호
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• pp.327-328
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• 2017

Despite provision of drinking water as the most common method of occupational heat stress prevention, there remains confusion in hydration messaging to workers. During work site interactions in a hot and humid climate, workers commonly report being informed to consume tepid fluids to accelerate rehydration. When questioned on the evidence supporting such advice, workers typically cite that fluid absorption is delayed by ingestion of chilled beverages. Presumably, delayed absorption would be a product of fluid delivery from the gut to the intestines, otherwise known as gastric emptying. Regulation of gastric emptying is multifactorial, with gastric volume and beverage energy density the primary factors. If gastric emptying is temperature dependent, the impact of cooling is modest in both magnitude and duration (${\leq}5$ minutes) due to the warming of fluids upon ingestion, particularly where workers have elevated core temperature. Given that chilled beverages are most preferred by workers, and result in greater consumption than warm fluids during and following physical activity, the resultant increased consumption of chilled fluids would promote gastric emptying through superior gastric volume. Hence, advising workers to avoid cool/cold fluids during rehydration appears to be a misinterpretation of the research. More appropriate messaging to workers would include the thermal benefits of cool/cold fluid consumption in hot and humid conditions, thereby promoting autonomy to trial chilled beverages and determine personal preference. In doing so, temperature-based palatability would be maximized and increase the likelihood of workers maintaining or restoring hydration status during and after their work shift.

• 대한환경공학회지
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• 제29권6호
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• pp.728-733
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• 2007

본 연구에서는 개인용 컴퓨터(PC) 내부의 시료를 채취하여, 세균의 CFU와 곰팡이의 종류를 분석하였다. 시료는 대중 PC 이용 시설(PC방), 대학실험실 및 대학 전산실습실의 PC 51대에서 채취하였다. CFU(colony forming unit)법을 이용한 세균수의 경우, 컴퓨터 총 작동시간이 증가할수록 PC 내부의 세균수는 증가하는 것으로 확인되었으며$(r^2=0.90)$, PC 내부 부품 중에서는 CPU 냉각 팬에서 가장 높은 수치로 확인되었다(평균 605 $CFU/cm^2$). 곰팡이의 경우, 다수의 유해성을 지닌 곰팡이가 검출되었으며, 그 중 Aspergillus sp.와 Penicillium sp.가 가장 많은 비율로 존재함이 확인되었다. 또한 PC 내부에서 채취된 먼지에서는 mg 당 212 CFU의 세균이 발견되었다. 본 연구의 결과, PC 내부에는 여러 다양한 종류의 미생물이 존재한다는 것을 확인하였으며, 이 결과는 PC의 취급, 사용 및 정비 시 각종 미생물에 의한 감염의 가능성이 있다는 것을 나타내고 있다.

• 설비공학논문집
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• 제14권12호
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• pp.1102-1139
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• 2002

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2000 and 2001 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) 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 technologies were widely applied for developing facilities and their systems. (2) Most of papers related with heat transfer analysis and heat exchanger shows dealt with convection, evaporation, and channel flow for the design application of heat exchanger. The numerical heat transfer simulation studies have been peformed and reported to show heat transfer characteristics. Experimental as well as numerical studies on heat exchanger were reported, while not many papers are available for the system analysis including heat exchanger. (3) A review of the recent studies on heat pump system shows that performance analysis and control of heat pump have been peformed by various simulations and experiments. The research papers on multi-type heat pump system increased significantly. The studies on heat pipe have been examined experimently for change of working characteristics and strut lure. Research on the phase change has been carried out steadily and operation strategies of encapsulated ice storage tank are reported experimentally in several papers. (4) A review of recent studies on refrigeration/air conditioning system have focused on the system performance and efficiency for new alternative refrigerants. Evaporation and condensation heat transfer characteristics are investigated for tube shapes and new alternative refrigerants. Studies on components of refrigeration/air conditioning system are carried to examine efficiency for various compressors and performance of new expansion devices. In addition to thermophysical properties of refrigerant mixtures, studies on new refrigerants are also carried out, however research works on two-phase flow seemed to be insufficient. (5) A review of the recent studies on absorption cooling system indicates that heat and mass transfer phenomena have been investigated to improve absorber performance. Various experimental data have been presented and several simulation models have been proposed. A review of the recent studies on duct and ventilation shows that ventilation indices have been proposed to quantify the ventilation performance in buildings and tunnels. Main efforts have been focused on the applications of ventilation effectiveness in practice, either numerically using computational fluid dynamics or experimentally using tracer gas techniques. (6) Based on a review of recent studies on indoor thermal environment and building service systems, research issues have mainly focused on many innovative ideas such as underfloor air-conditioning system, personal environmental modules, radiant floor cooling and etc. Also, the new approaches for minimizing energy consumption as well as improving indoor environmental conditions through predictive control of HVAC systems, various activities of building energy management and cost-benefit analysis for economic evaluation were highlighted.

• 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.

• 한국조리학회지
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• 제15권2호
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• pp.268-281
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• 2009

본 연구는 서울 경기도에 위치한 패밀리 레스토랑에 근무하는 직원들을 대상으로 식품 위생과 식품 안전 지식 수준을 2008년 10월 10일부터 10월 31일까지 조사하였으며, SPSS를 이용하여 149부(회수율 82.8%)를 분석하였다. 설문조사에 참여한 조사대상자의 정기 교육 이수는 79.9%, 정기 교육 이수의 경우 국내 기업 직원 76.7%, 국외 기업 82.9%로 조사되었다. 식품 위생 및 식품 안전 영역별 전체평균 점수는 식중독과 식품은 3.95점/5점, 개인 위생은 2.37점/3점, 식품 위생 및 환경위생은 6.41점/9점, 식품 안전은 1.86점/3점으로 전체 평균은 14.03점/20점(71.5점/100점)으로 나타났다. 전체점수 비교에서는 국내 기업이 13.74점/20점, 국외 기업이 14.3점/20점으로 국외 기업이 높게 나타났는데, 국내 기업과 국외 기업 비교 시 식중독과 식품 영역이 주방 직원과 홀 직원에서 유의적인 영향을 미쳤다. 그리고 정기 교육 이수자그룹이 네 영역 모두 높은 점수를 보여 정기 교육의 필요성과 교육의 효과를 입증하였고, 지식 수준에서 낮은 정답율을 보인 항목으로 '위험 온도 범주', '세균의 증식', '해동 방법', '냉각 방법', '온도 관리'로 시간-온도 관리에 대한 교육이 필요한 것으로 나타났다. 인구통계학적으로 본 차이검증에서는 소속, 학력, 직장 경력(현재, 전체), 정기 교육 수혜 여부가 유의적인 차이를 나타냈는데, 특히 정기 교육 수혜에서는 교육 이수자 그룹이 네 영역 보두 높은 점수를 보여 정기 교육의 효과를 입증하였다.