• Journal of Energy Engineering
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• v.21 no.4
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• pp.325-338
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• 2012

Currently, there are the technologically urgent needs of fabricating the hyper coal (HC) based on the approach to extracting mainly effective organics from low rank coals (LRCs), because some industrial countries pursue global sustainability dealing with hot issues such as local energy supply security as well as global warming. In this study, as of the fabrication of clean HCs via LRCs upgrading, we comprehensively review the R&D status of two solvent extraction technologies, namely, Ohm heating (OH) and microwave irradiation (MI) extraction processes on the basis of the performance indicator such as a HC extraction yield.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1328-1333
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• 2005

This paper presents the temperature-pressure characteristics of a new SMH actuator using a Peltier module. The SMH actuator is characterized by its small size, low weight, noiseless operation, and compliance similar to that of the human body. The simple SMH actuator, consisting of the plated hydrogen-absorbing alloys as a power source, Peltier elements as a heat source, and a cylinder with metal bellows as a functioning part has been developed. To improve the thermal conductivity of the hydrogen-absorbing alloy, an assembly of copper pipes has been used. It is well known that hydrogen-absorbing alloys can reversibly absorb and desorb a large amount of hydrogen, more than about 1000 times of their own volume. The hydrogen equilibrium pressure increases when hydrogen is desorbed by heating of the hydrogen-absorbing alloys, whereas by cooling the alloys, the hydrogen equilibrium pressure decreases and hydrogen is absorbed. The new special metal hydride (SMH) actuator uses the reversible reaction between the heat energy and mechanical energy of a hydrogen absorbing alloys. The desirable characteristics of SMH actuator, which makes it suitable for the uses in medical and rehabilitation applications, have been also studied. For this purpose, the characteristics of the new SMH actuator for different temperature, pressure, and external load were explored.

• Fire Science and Engineering
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• v.11 no.1
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• pp.21-35
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• 1997

The natural convection and combined heat transfer induced by fire in a rectangular enclosure is numerically studied. The model for this numerical analysis is partially opened right wall. The solution procedure includes the standard k-$\varepsilon$ model for turbulent flow and the discrete ordinates method (DOM) is used for the calculation of radiative heat transfer equation. In numerical study, SIMPLE algorithm is applied for fluid flow analysis, and the investigations of combustion gas induced by fire is performed by FAST model of HAZARD I program. In this study, numerical simulation on the combined naturnal convection and radiation is carried out in a partial enclosure filled with absorbed-emitted gray media, but is not considered scattering problem. The streamlines, isothermal lines, average radiation intensity and kinetic energy are compared the results of pure convection with those of the combined convection-radiation, the combined heat transfer. Comparing the results of pure convection with those of the combined convection-radiation, the combined heat transfer analysis shows the stronger circulation than those of the pure convection. Three different locations of heat source are considered to observe the effect of heat source location on the heat transfer phenomena. As the results, the circulation and the heat transfer in the left region from heating block are much more influenced than those in the right region. It is also founded that the radiation effect cannot be neglected in analyzing the building in fire. And as the results of combustion gas analysis from FAST model, it is found that O2 concentration is decreased according to time. While CO and CO2 concentration are rapidly increased in the beginning(about 100sec), but slowly decreased from that time on.

• Korean Journal of Materials Research
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• v.23 no.4
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• pp.246-249
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• 2013

Nano-sized ${\beta}$-SiC nanoparticles were synthesized combined with a sol-gel process and a carbothermal process. TEOS and carbon black were used as starting materials for the silicon source and carbon source, respectively. $SiO_2$ nanoparticles were synthesized using a sol-gel technique (Stober process) combined with hydrolysis and condensation. The size of the particles could be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The average particle size and morphology of synthesized silicon dioxide was about 100nm and spherical, respectively. The average particles size and morphology of the used carbon black powders was about 20nm and spherical, respectively. The molar ratio of silicon dioxide and carbon black was fixed to 1:3 in the preparation of each combination. $SiO_2$ and carbon black powders were mixed in ethanol and ball-milled for 12 h. After mixing, the slurries were dried at $80^{\circ}C$ in an oven. The dried powder mixtures were placed in alumina crucibles and synthesized in a tube furnace at $1400{\sim}1500^{\circ}C$ for 4 h with a heating rate of $10^{\circ}C$/min under flowing Ar gas (160 cc/min) and furnace cooling down to room temperature. SiC nanoparticles were characterized by XRD, TEM, and SAED. The XRD results showed that high purity beta silicon carbide with excellent crystallinity was synthesized. TEM revealed that the powders are spherical shape nanoparticles with diameters ranging from 15 to 30 nm with a narrow distribution.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.130-131
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• 2011

박막의 제조는 많은 연구의 가장 기초가 되는 시편을 만드는 과정으로 현대의 과학기술에서 매우 중요한 공정 중의 하나이다. 그러나 이러한 박막의 제조는 제조하는 사람의 숙련도나 장치에 의존하며 경우에 따라서는 원하는 특성의 박막을 제조하는 것이 매우 어려운 작업이 되기도 한다. 따라서 경험이 없는 연구자의 경우는 때때로 까다로움과 번거로움을 느끼게 되며, 안정된 공정을 찾기까지 많은 시간을 소비 하게 된다. 특히 부적절한 증발방법의 선정에 따른 실험 결과는 경제적인 손실을 초래할 뿐만 아니라 실험하는 사람을 좌절시키는 가장 큰 요인이 되어왔다. 진공증착에 의한 박막의 제조는 증발법과 스퍼터링, 이온플레이팅 등의 방법이 있으며 이중 증발을 이용한 박막의 제조에는 저항가열 증발, 전자빔 가열 증발, 유도가열 증발 등의 방법으로 구분하고 있다. 저항가열 증발원은 가격이 저렴하다는 장점은 있으나 증발원이 손쉽게 파손되거나 증발량이 일정하지 않아 박막의 정밀 제어가 어려울 뿐만 아니라 때에 따라서는 1 ${\mu}m$ 이상의 후막 형성에도 어려움이 있는 등 많은 제약이 있다. 따라서 적절한 증발원의 선정이 실험의 효율성을 좌우하는 경우가 많다. 적절한 증발원의 선정과 효율적인 실험을 위해 증발원 제조회사에서는 증발원의 선정과 증발 조건과 관련된 자료를 카탈로그 형태로 발행하고 있다. 그러나 그러한 자료만으로는 객관적인 정보를 얻기에 충분하지 못한 경우가 많으며, 어떤 경우에는 저자 등의 경험과 일치하지 않는 정보도 포함하고 있었다. 전자빔 증발원은 냉각이 되는 Crucible에 물질을 담고 고전압의 전자빔으로 물질을 가열시켜 증발시키는 증발원으로 1960년대 이후 박막 제조 실험에 이용되기 시작하였다. 전자빔은 고순도의 피막 제조가 가능하고 증발물질의 교체가 쉬우며 고속 증발이 가능함은 물론 다층막의 제조가 용이하고 증발물질의 제조비용이 저렴하다는 장점이 있다. 이러한 장점 때문에 1970년대 이후에는 전자빔을 이용한 박막제조가 폭 넓게 이루어졌고 이때를 즈음하여 전자빔을 이용한 물질의 증발 특성이 논문으로 발표되기도 하였다. 본 연구에서는 증발에 관한 저자들의 경험을 바탕으로 저항가열과 전자빔을 이용하여 증발실험을 진행한 물질계를 중심으로 각 물질의 증발특성과 가장 효율적인 Liner 등에 대해 기술하였다. 특히, 각종 물질의 증발 특성을 체계화함은 물론 효율적인 증발 방법을 객관적인 Data와 함께 제공하여 효과적인 박막 제조 실험에 도움이 되고자 하였다.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.179-184
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• 2011

The development of new energy has attracted consideration attention due to the high oil price and environmental problems. In advanced country, they have tried to carry out a long range plan for energy. We need to develop new energy for Low Carbon Green Growth in Korea. The building is 30% among ratio of energy consumption in Korea. And in the past, heating energy was high ratio for energy using at home. But recently, the demand for cooling energy keeps growing due to rising average temperature on the earth and improvement of life quality. In this situation, the energy of lake water and ocean water has studied to utilize in advanced country because of low temperature at underwater. But the study for deep water is still a lot left to do. In this study, we analyzed district cooling system and the present condition. Analyzing the deep lake water cooling system in Toronto, we found an application of district cooling system using deep ocean water. Deep lake water uses heat source for district cooling and water source for city in Toronto. So reducing the initial cost, this city had economic effect. When DLWC was applied at existing building, the heat exchanger was installed instead of cooling tower and refrigerator. And the heat exchanger used to connect main pipe with cool water on city. System using deep ocean water can be applied as a similar way to supply cool water from lake to building.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.6 no.1
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• pp.9-16
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• 2010

The aim of this study is to verify the performance of water-to-air multi-heat pump system with a vertical U-tube GLHX(U-tube system) and a double tube GLHX(double tube system), which were installed in a school building located in Asan. For analyzing the performance of the GSHP system, we monitored various operating da~ including the water temperature of inlet and outlet of the ground heat exchanger, mass flow rate, and power consumption. Daily average COP of the single U-tube system and the double tube system were 4.5 and 4.2 at cooling mode and were 3.5 and 3.8 at heating mode. As a result, We know that performance of water-to-air multi-heat pump unit is reliable at actual condition operated in a part load conditions for all day.

• Journal of the Korean Solar Energy Society
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• v.38 no.2
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• pp.55-66
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• 2018

South Korea aims to shift the 20 percent of electricity supplement from the fossil fuel including the nuclear to renewable energy systems by 2030. In order to realize this agenda in the buildings, the plus energy house is necessary to increase the renewable energy supplement beyond the zero energy house. This paper suggested KePSH (KIER Energy-Plus Solar House) and energy performance of house and renewable energy systems was investigated. The KePSH has the target of generating 40% surplus energy than the conventional house energy consumption. The plus energy house is the house that generates surplus energy from the renewable energy sources than that consumes. In order to minimize the cooling and heating load of the house, the shape design and passive parameters design were conducted. Based on the experimental data of the plug load in the typical house, the total energy consumption of the house was estimated. This paper also suggested renewable energy sources integrated HVAC system using air-source heat pump system. Two cases of renewable energy system integration methods were suggested, and energy performance of the cases was investigated using TRNSYS 17 program. The results showed that the BIPV (building integrated photovoltaic) system (i.e., CASE 1) and BIPV and BIST system (i.e., CASE 2) shows 42% and 29% of plus energy rate, respectivey. Also, CASE 1 can generate 59% more surplus energy compared with the CASE 2 under the same installation area.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.1
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• pp.90-97
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• 2001

A high frequency resonant inverter consisting of iliree unit Half-Bridge serial resommt inverter used as power source of induction heatmg at high frequency is presented in this paper. As a output [Dwer control strategy, sequencial time-sharing gate contml methcd is applied. This methcd is TDM(Time Division Multiplexing), which is broadly used with digital and analog signals transmission in communication system 1be analysis of the proposed circuit is generally described by using the normalized pararmenters. Also, the principle of basic operating and the its characteristics are estimated by the parameters such as switching frequency, load resistance. Also, according to the calculated characteristics value, a method of the circuit design and operating characteristics of the inverter is proposed. This paper proves the validity of theoretical analysis through the Pspice. This proposed inverter show that it can be practically used in future as power source system for induction heating application, DC-DC converter etc. r etc.

• Journal of Biosystems Engineering
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• v.10 no.2
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• pp.1-11
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• 1985

A double pipe grain heater using engine exhaust gas as a heat source was developed. The performance of the grain heater was examined with soybeans as a test material experimentally and numerically using a mathematical model constructed. The following conclusions were drawn: 1. The modified screw conveyor used in the grain heater has a characteristic of decreasing capacity with increasing speed at speeds above 60 rpm. Operation with speeds below 60 rpm is recommended. 2. Heating soybeans by the heater at soybean flow rate up to 100 kg/hr, inlet temperature of the exhaust gas to the heater are recommended as above $400^{\circ}C$, $300^{\circ}C$, and $200^{\circ}C$ roughly for a 2, 5, and 10 kW engine, respectively. 3. Temperature increments of soybean by the heater at soybean flow rates ranged from 25 to 100 kg/hr are in the ranges of $6^{\circ}C-35^{\circ}C$, $15^{\circ}C-88^{\circ}C$, and $15^{\circ}C-140^{\circ}C$ with exhaust gas from a 2, 5, and 10 kW engine, respectively, at an exhaust temperature of $500^{\circ}C$. 4. Thermal efficiency of the heater at soybean flow rates ranged from 25 to 100 kg/hr are in the ranges of 35-37%, 28-34%, and 20-29% with exhaust gas from a 2, 5, and 10 kW engine, respectively. 5. The grain heater can be used to heat the other grain, also, without any bad effect from the exhaust gas used as a heat source.