• 설비공학논문집
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• 제26권5호
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• pp.218-223
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• 2014

Korea District heating corp. recently give an attention to combine the district heating and supply pipes as a two pipe system that are in the present system separated with room heating and warm water supply pipe, and the two pipe system is commonly applied for heating service in European countries. In the new two pipe system, only one heat source is supplied to a house and partitioned into room heating and warm water supply by household substation. So the effective distribution of supplied heat source in accordance to user intention is very important. This paper presents the development and performance test of three-way proportional control valve for a combined heat source system in district heating. The proposed valve is controlled to partition heat source into two different directions : hot water distributor for space heating and household substation for warm water supply in response to the pressure drops of tap water caused by the user. The performance investigation is shown within 3% of error compared to the theoretical model of the three-way proportional valve and its controllability is verified.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.162-167
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• 2000

Construction machinery includes an engine enclosure separated from a cooling system enclosure by a wall to reduce noise and advance cooling system performance. For this structure, however, the axial fan cannot be of benefit to the engine room, and so the temperature rise in the engine room makes several bad conditions. This paper proposes that hot air in engine room is evacuated tv secondary pipe using jet pump. This paper demonstrates the structure and the effect of jet pump and useful guideline on design of area, length, and shape of secondary pipe to maximize the effect of jet pump.

• 대한기계학회논문집
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• 제11권3호
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• pp.409-424
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• 1987

본 연구에서는 유한차분법보다는 정확도가 약간 떨어지지만 공기조화 분야의 계산에 적합하고 계산시간이 적게 소요되는 응답계수법을 사용하여 온수온돌방계의 비 정상 열전달을 해석하였다.

• 한국철도학회논문집
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• 제13권5호
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• pp.481-487
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• 2010

구형 지하철 전동차의 내장재에 대하여 ISO 9705 시험 설비를 이용하여 화재시험을 수행하였다. 시험에 사용된 점화용 버너는 CEN/TS 45545-1 규정에 따라 출력을 조정하였다. 이 내장재 화재시험의 목적은 화원의 규모에 따라서 철도차량에서의 화재거동과 화염의 전파 경로를 평가함과 동시에 객실 내장재의 화재가 플래시오버로 진행하는 경로의 화재 데이터를 제공하는 것이다. 시험으로부터 시간에 따른 위치 별 온도 값과 열류량 및 열방출률을 측정하였고 열방출률은 수정된 화염면적기반 합량법으로 계산한 결과와 비교하였다. 이 시험 결과는 CFD 화재 시뮬레이션 기법을 이용한 철도차량 화재해석의 검증 데이터로 활용될 수 있을 것이다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.63-66
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• 2005

Nanoimprint lithography (NIL) process at room temperature has been newly proposed in recent years to overcome the shape accuracy and sticking problem induced in a conventional NIL process. Success of the room temperature NIL relies on the accurate understand of the mechanical behavior of the polymer. Since a conventional NIL process has to heat a polymer above the glass transition temperature to deform the physical shape of the polymer with a mold pattern, viscoelastic property of polymer have major effect on the NIL process. However, rate dependent behavior of polymer is important in the room temperature NIL process because a mold with engraved patterns is rapidly pressed onto a substrate coated with the polymer by the hydraulic equipment. In this paper, finite element analysis of the room temperature NIL process is performed with considering the strain rate dependent behavior of the polymer. The analyses with the variation of imprinting speed and imprinting pattern are carried out in order to investigate the effect of such process parameters on the room temperature NIL process. The analyses results show that the deformed shape and imprint force is quite different with the variation of punch speed because the dynamic behavior of the polymer is considered with the rate dependent plasticity model. The results provide a guideline for the determination of process conditions in the room temperature NIL process.

• 설비공학논문집
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• 제22권8호
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• pp.567-572
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• 2010

Air shift type heat pump is combined heat recovery ventilator and refrigerator, and it is installed an air shifter changing air flow. And so it is an perfect AHU(Air Handling Unit) capable to cooling, heating, ventilation and heat recovery. Therefore, an experimental study has been carried out to investigate the operating performance in winter for this system. An experimental data are room temperature, inlet/outlet temperature of condenser, evaporator and heat exchanger. They have been measured as the variation of outdoor temperature. The results, in case of rising above freezing, the air shift type heat pump system is operated normally, and the heating COP is 3.0~4.2 by varying outdoor temperature from $-3^{\circ}C$ to $15^{\circ}C$.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.288-293
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• 2005

The pressure distribution and heat transfer coefficient were measured at room temperature in the high suspension density CFB heat exchanger with multiple vertical tubes and the effective density of CFB was determined. The theoretical model for predicting heat transfer coefficient was developed in this study. The model predictions were compared with the measured heat transfer coefficient to show relatively good agreement between them.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.345-350
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• 2008

The present study has been conducted to develop a heat recovery system for a 1 MW class gas engine based cogeneration system. In the cogeneration system, heat is recovered from two parts, which are jacket water and exhaust gas. The heat from the jacket water is recovered by a plate type heat exchanger and used for the room heating and/or hot water supply. The heat from the exhaust gas is used to generate steam. For both of the heat recovery devices, 1/5 scaled tests are performed and the data are compared to the conventional correlations for the design.

• 대한치과보철학회지
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• 제28권1호
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• pp.25-41
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• 1990

The purpose of this study was to evaluate and compare the dimensional changes of relined dentures with a light-curing resin, a heat-curing resin, and a direct, hard reline resin. And also to measure the transverse strength, impact strength, surface hardness of the three resins used in relining. The surface textures of three resins also of evaluated by using scanning electron microscope. Through analyses on the data from this study, the following conclusions were obtained. 1. Impact strength of heat-curing resin was highest, and direct, hard reline resin higher, light-curing resin lowest. 2. Transverse strength of heat-curing resin was highest, and direct, hard reline resin and light-curing resin was lower and not signiicantly different. 3. Surface hardness of light-curing resin was lighest, heat-curing resin higher, and direct, hard reline resin was lowest. 4. After storage of the relined dentures for 1 day and 1 week in water at room temperature, linear shrinkage of distance between the reference points in the maxillary base relined with direct, hard reline resin was lowest, and those relined with light-curing resin and heat-curing resin were lower and were not significantly different. 5. After storage for 4 weeks in orator at room tempeature, linear shrinkage of distance between ridge crests of dentures relined with heat-curing resin was highest and that of distance between denture borders was not significantly different. 6. The dimensional changes of relined dentures during storage in water was not significant except those of distance between denture borders relined with light-curing resin at 1 day and 1 week storage in water. 7. At low magnification (x40) of SEM examination, the surface textures of three resins were similar except light-curing resin which had some defects. At high magnification (x200), the surface textures of hard, direct reline resin were smooth with little defects, but those of heat-curing resin and light-curing resin w ere irregular.

• 대한간호학회지
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• 제4권1호
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• pp.95-106
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• 1974

The Purpose of this study was to observe the body temperature changes of newborn infants in general crib and electric heat crib after birth for the period required to reach the optimum body temperature. Forty-seven newborn infants who were delivered at Seoul National University Hospital during the period from June 12 to September 13, 1973 were chosen as Subjects for this study. The criteria for the choice of subjects were the babies with normal spontaneous delivery; body weight 2.5kg and over at birth; Apgar so ore seven and over and gestation period over thirty-six weeks. Of these subjects, by random sampling thirty-one newborn infants were placed in the general crib and sixteen in the electric-heat crib. The rectal body temperature of these newborn infants were taken and recorded at fifteen-minute interval for the first one hour period after birth, at thirty minute interval for the next two hours and at one hour interval for the remaining period up to eight hours. The results of the study were as follows: 1. The mean body temperature of the newborn infants on admission to nursery ranged from 98.7℉. to 99℉. irrespective of the body weight and the room temperature. 2. There was a significant difference in the body temperature changes of the newborn infants as a total between the general crib and the electric-heat crib from three to eight hours after birth. It was found that the body temperature of the newborn infants in the electric-heat crib was significantly higher than that of the newborn infants in the general crib. 3. In comparison with the body temperature changes of the newborn infants in the general crib, the newborn infants in the electric- heat crib exhibited significantly higher body temperatures in all three body weight groups; from four to eight hours after birth in the 2.5-2.9kg body weight group; from three to seven hours after birth in the 3.0-3.4kg body weight group; from two and half to six hours after birth in the group with body weight over 3.5kg. 4. Time required to reach 98℉. of body temperature was four hours in the 3.5-2.9kg body weight group, three hours in the 3.0-3.4kg. body weight group and two and half hours in the group with body weight over 3.5kg in the electric- heat crib. In the general crib, it took over eight hours in the 2.5-2.9kg body weight group and five hors in both the 3.0-3.4kg and over 3.5kg body weight group to reach 98℉ of body temperature. 5. The lowest mean body temperature of newborn infants in both general and electric- heat crib appeared in forty-five minute after birth and the temperature ranged from 96.4℉ to 96.5℉. 6. The mean body temperature of the newborn infants in the general crib was increased as the room temperature. 7. The body weight, the room temperature and the time elapsed after birth fore proved to be significant factors influencing the body temperature changes of newborn infants. From tile above results, the three hypotheses were positively accepted.