• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2007년도 춘계학술발표논문집
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• pp.294-296
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• 2007

본 논문은 고온 고압 수증기를 활용한 유기성 폐기물의 가수분해현상과 이를 이용한 퇴비 등의 재활용 방안을 제시한다. 사료화의 경우는 3.27 기압 $135^{circ}C$ 전후의 포화수증기로 교반처리하여 영양소 파괴를 줄이고 멸균 및 가수분해가 일어나게 하여 소화가 잘되는 사료를 만들 수 있고, 퇴비화의 경우는 16기압. $200^{circ}C$ 전후의 포화수증기로 교반처리하여 가수분해, 산가수분해, 열분해 및 탄화가 일어나도록 하여 목초액과 활성탄을 함유한 보온성, 보비성 및 통기성이 양호한 퇴비를 만든다. 응축수는 액비로 사용가능하므로 완전 재활용이 가능하다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.104-106
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• 1995

A curious resistivity anomaly in high curie point barium-lead-titanate materials with positive temerature coefficient of resistivity (PTCR) has been observed just below the curie point, besides the normal PTCR anomaly. The additional resistivity anomaly was observed in the resistivity-temperature characteristics.

• 한국화재소방학회논문지
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• 제7권2호
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• pp.24-28
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• 1993

The flash point for flammable liquids (alcohol, aromatic compounds) were measured by Penskt-Martens's measuring apparatus with closed cup. As a result, it was observed that the flash points had the regular tendency according to the carbon number and the molecular structure. Consequently, the flash point for the alcohols were increased in proportion to the increase of the carbon number and branch number. The differences between the literature and experimental data are 14.6% for the relative error and 3.46$^{\circ}C$ in average for the measuring temperature.

• 한국화재소방학회논문지
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• 제15권2호
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• pp.1-5
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• 2001

전분 분말의 온도에 따른 열적 안정성을 조사하기 위하여 시차주사열량계(DSC, Differential Scanning Calorimeter) 빛 열중량 분석기(TGA, Thermogravimetric Analysis)를 이용하여 온도에 따른 발열개시 온도, 발열량 등을 조사하였으며, 자연발화 시험기를 이용하여 시료량에 따른 전분 분말의 연소특성을 시간에 따른 온도의 변화를 측정하여 연소개시시간 및 연소시 상승하는 온도를 측정함과 동시에 육안으로 연소특성을 조사하고자 하였다. 한편 자연발화 시험기 내부의 공기흐름에 따른 연소특성을 조사하기 위하여 송풍과 무풍 상태에서의 연소특성을 조사하고자 하였다. 선분 분말의 열분석 결과 승온속도가 증가할 수록 발열개시온도가 저온부로 이동하고 있으며, 발열량도 크게 증가하였다. 또한, 자연발화 실험결과 전분의 양이 증가할수록 훈소 개시온도가 낮아지고, 연소형태는 모두 훈소였다. 자연발화 시험기 내부가 송풍상태일 때 보다 무풍상태로 실험하였을 경우 훈소 개시시간이 다소 빨라지고 있으며, 발열최고온도도 크게 나타났다.

• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.1002-1009
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• 2004

Direct contact air conditioning systems, in which heat and mass are transferred directly between air and water droplets, have many advantages over conventional indirect contact systems. The purpose of this research is to investigate the cooling and heating performances of direct contact air conditioning system for various inlet parameters such as air velocity, air temperature, water flow rate and water temperature. The experimental apparatus comprises a wind tunnel, water spray system, scrubber, demister, heater, refrigerator, flow and temperature controller, and data acquisition system. The inlet and outlet conditions of air and water are measured when the air contacts directly with water droplets as a counter flow in the spray section of the wind tunnel, and the heat and mass transfer rates between air and water are calculated. The droplet size of the water sprays is also measured using a Malvern Particle Analyzer. In the cooling conditions, the outlet air temperature and humidity ratio decrease as the water flow rate increases and as the water temperature, air velocity and temperature decrease. On the contrary, the outlet air temperature and humidity ratio increase in the heating conditions as the water flow rate and temperature increase and as the air velocity decreases.

• Geomechanics and Engineering
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• 제12권4호
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• pp.707-721
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• 2017

The objective of this paper is to experimentally study the consolidation of saturated silty clay subjected to repeated heating-cooling cycles using a modified temperature-controlled triaxial apparatus. Focus is placed on the influence of the water content, confining pressure, and magnitudes and number of thermal loading cycles. The experimental results show that the thermally induced pore pressure increases with increasing water content and magnitude of thermal loading in undrained conditions. After isothermal consolidation at an elevated temperature, the pore pressure continues to decrease and gradually falls below zero during undrained cooling, and the maximum negative pore pressure increases as the water content decreases or the magnitude of thermal loading increases. During isothermal consolidation at ambient temperature after one heating-cooling cycle, the pore pressure begins to rise due to water absorption and finally stabilizes at approximately zero. As the number of thermal loading cycles increases, the thermally induced pore pressure shows a degrading trend, which seems to be more apparent under a higher confining pressure. Overall, the specimens tested show an obvious volume reduction at the completion of a series of heating-cooling cycles, indicating a notable irreversible thermal consolidation deformation.

• 설비공학논문집
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• 제22권6호
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• pp.398-403
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• 2010

The drag reduction(DR) of non-ionic surfactant and polymer according to the variation of fluid velocity, temperature and surfactant concentration was investigated experimentally. For this experiment, the kind of surfactant was non ionic amine-oxide and the kinds of polymer were polyacrylamide and xantan gum. An experimental apparatus equipped with one water storage tanks was built and two flow meters, two pressure gauges for data logging system was installed. Results showed that the kinds of polymer, polyacrylamide and xantan gum, had DR of below 20% for below 500 ppm in fluid temperature of $50{\sim}80^{\circ}C$. But the kind of surfactant, amine oxide, had DR of above 40% for 500~1000 ppm in fluid temperature of $50{\sim}80^{\circ}C$. As a result, amin oxide showed better materials to use to the district heating system.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.695-702
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• 2003

In this study, an experimental apparatus has been designed and set-up to analyse the dissociating phenomena of hydrate in porous rock using electric heating method supplied at downhole. The electric heat injecting experiments have been performed to investigate the heat transfer within the core, the dissociating phenomena of hydrate, and the productivities of dissociated gas and water. These experiments were under constant heat injecting method as well as preheating methods. From the experimental results, it is seen that the hydrates is dissociated along the phase equilibrium curve and dissociation of hydrate is accelerated with heat. The injected heat is consumed for the dissociation and also it is lost together with outflow of the dissociated gas and water. From the investigation of gas producing behavior for various heat injecting methods, as the injected heat is greater, dissociation is accelerated faster at outlet and hence the initial gas production becomes higher. Also, it is shown that the initial gas productivity under the constant heating method is better, however, the energy efficiency is low because of smaller amount of the produced gas comparing to the amount of heat injected. In the experiments of preheating method, it was seen that gas production only initial stage is different with the preheating time, but the producing behaviors of gas production are similar.

• Journal of Advanced Marine Engineering and Technology
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• 제31권5호
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• pp.558-566
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• 2007

The performance characteristics of water-chilling heat pump using $CO_2$ with respect to variation of refrigerant charge amount was investigated experimentally. An experimental apparatus is consisted of a compressor, a gas cooler, an expansion valve, an evaporator and a liquid receiver. All heat exchangers used in the test rig are counter-flow-type heat exchangers with concentric dual tubes, which are made of copper. The gas cooler and the evaporator consist of 6 and 4 straight sections respectively arranged in parallel, each has 2400 mm length. The experimental results summarize as the followings : As the refrigerant charge ratio of $CO_2$ heat pump system increases, the discharge pressure and compressor ratio increases, but mass flow rate of refrigerant decreases. Also the compressor work increases with the increase of refrigerant charge ratio. However, the heating and cooling capacity of $CO_2$ heat pump decreases as the refrigerant charge ratio increases. The maximum heating COP of $CO_2$ heat pump system presented at 0.25 refrigerant charge ratio. It is possible to confirm the optimum charge ratio of $CO_2$ heat pump system by the viewpoint of heating COP.

• 대한화학회지
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• 제45권5호
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• pp.481-490
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• 2001

이 연구의 목적은 제 6차 교육과정에 의한 중학교 1학년 과학 교과서 분별 증류 실험의 문제점을 파악하고, 중학생들이 분별 증류 실험을 능률적으로 수행할 수 있는 실험 방법을 제시하고자 하는 것이다. 이를 위한 첫 번째 단계로서 현재 사용되고 있는 8종의 과학 교과서를 분별 증류 실험 장치와 액체 혼합물의 종류에 따라 6가지로 분류하였다. 두 번째 단계로서 액체 혼합물을 가열 방법에 따라 직접 가열과 물 중탕 가열로 나누어 교과서 실험과정에 따라 같은 실험을 세 번 실시하였다. 세 번재 단계로서 실험 결과의 문제점을 해결하기 위한 대안 실험을 실시하였다. 대안 실험에서는 알코올 램프로 직접가열 하는 방법과 기름 중탕으로 가열하는 방법, 그리고 가열 맨틀을 사용하여 가열하는 방법을 사용하였다. 연구결과, 가지달린 둥근 플라스크를 직접 가열하는 실험 결과가 가지 달린 시험관을 물 중탕으로 가열하는 실험 결과보다 이론적인 결과에 근접하였다. 그리고 가지 달린 둥근 플라스크를 직접 가열하는 실험에서 플라스크 윗 부분을 보온해 주는 실험이 보온하지 않은 실험보다 실험 결과가 더 나았다. 대안 실험에서는 액체 혼합물의 증류 온도 증가를 보면서 가열 맨틀의 가열 온도를 올려 준 실험의 결과가 이론적인 결과에 가장 가까웠다. 이러한 연구 결과로부터 가지 달린 시험관을 물 중탕으로 가열하는 분별 증류 실험장치는 탐구실험 수업에 부적절한 것이므로 개선이 요구되며, 중학교 과학실 여건을 고려할 때, 액체 혼합물의 증류 온도 증가를 보면서 가열 맨틀의 가열 온도를 변화시키는 분별 증류 실험이 가장 능률적인 방법임을 알 수 있었다.