• Tribology and Lubricants
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• v.29 no.5
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• pp.310-317
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• 2013

To reduce vehicle fuel consumption due to not only driving but also air conditioning, battery-operated non-starting conditioning systems with thermoelectric modules and without mechanical elements like compressors are being manufactured for use by hybrid heavy trucks in the near future. In this study, the voltage and current consumed by a thermoelectric module were measured to determine the required battery power, and the performance of the conditioning system with air temperature, and humidity of the inlet/outlet modules and inside/outside the cabin for a truck, was evaluated using experimental apparatus under actual conditions. The results showed that, the thermoelectric module can be continously operated for about 1.5 h using existing 24 V batteries. The coefficent of performance(COP) of the cooling and heating modes was calculated to be an average 0.8-1.32. As expected, the heating performance was 30% more efficient than the cooling performance, which is general characteristic of thermoelectric modules.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.2
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• pp.127-133
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• 2002

The objectives of this paper are to develop an advanced GAX cycle named HGAX (Hybrid Generator Absorber heat exchanger) cycle, and to study the effect of key parameters on the cycle performance and the hot-water temperature from the condenser. New types of the HGAX cycle are developed by adding a compressor between the generator and the condenser- Type C (performance improvement and reduction of the generator temperature) and Type D (Hot-water temperature application). The solution temperature in the generator outlet is reduced to 168$^{\circ}C$ with the COP improvement of 19% compared to the standard GAX cycle. The hot-water temperature from the condenser is raised to 106$^{\circ}C$ for panel heating (Ondol heating) application.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.588-591
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• 2009

Ground source heat pump system; GSHPs is close to most practical use for early stage investment cost and energy efficiency in new renewable energies, and currently considered utilizing to the heat and cooling system of a building. Particularly, the case to utilize 'Standing Column well heat source gathering method' in the open standards process to have the excellent capability of gathering geothermal source is increased. But the research for the optimal design technology and the assessment of a pollution level of the ground to utilize a single well for gathering geothermal is insignificant and the design is insufficient. The heating and cooling system and the equipment to utilize a large size residential development to have over 1000 households have not developed yet. Therefore, our company developed 'geothermal hybrid system' which can construct the heat and cooling system using geothermal energy for a large size residential development of over 1000 households and conducted the evaluation of economic feasibility. Moreover we developed automatic equipment for gathering geothermal source and PLC (Programmable logic controller) to have optimal efficiency and FCU (fan coil unit) considering the floors of large size apartments.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1009-1011
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• 2001

This paper presents a new hybrid control scheme using Active-Clamped Class-E (ACCE) inverter of induction heating(IH) jar for high power applications. The proposed hybrid control scheme has characteristics, which act as class-E inverter at lower switch voltage and ACCE inverter at higher switch voltage than reference voltage of the main switch by feeding back voltage one as well as advantages of conventional ACCE inverter such as zero-voltage switching(ZVS) of the main switch and the reduced switch voltage due to the clamping circuit. Moreover, the proposed control method makes higher output power than conventional ACCE inverter control one since ACCE inverter is operated like class-E inverter at low voltage condition. The principle of the proposed control are explained in detail and the validity of the proposed control scheme is verified through the several interesting simulated and experimental results.

• Journal of the Korean Solar Energy Society
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• v.23 no.2
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• pp.51-58
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• 2003

PSHC(Prismatic Solar Hybrid Collector) is a passive solar system composed of prismatic acrly glazing, glazing and ventilating fan. This PSHC system is applied to effectively reduce heating ventilation load as well as lighting load. But so far no method appraising thermal performance of this PSHC system has been developed yet. To assess thermal performance of the PSHC system, a prototype PSHC experimental facility and TRNSYS subroutine type-205 model have been developed in Korea Institute of Energy Research (KIER). The results indicated that l)TRNSYS empirical model of PSHC has been properly modeled with actual performance data, 2)a more reliable source of weather data such as NASA and KIER weather station have been also obtained, and therefore, 3)the annual energy performance of PSHC could be assessed based on this proposed TRNSYS model.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.244-251
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• 2003

A two-dimensional BEM code, $FRACOD^{2D}$, was applied to simulate fracture initiation and propagation processes in a rock pillar during an in situ heater test of a rock pillar planned at the $\"{A}sp\"{o}$ Underground Rock laboratory of SKB, in Southern Sweden. To take the advantage of conventional BEM for simulating fracturing processes, but without efforts for domain integral transformation, a hybrid approach is developed to simulate the fracturing processes in rock pillar under coupled thermo-mechanical loading. The code FRACOD was used for simulating the fracture initiation and propagation processes with its boundary tractions reflecting the effects of the initial and redistributed thermomechanical stresses in the domain of interest at multiple excavation and heating steps were produced by a special algorithm of stress inversion, based on resultant thermo-mechanical stress fields at each excavation and heat loading step by a FEM code without considering fracturing processes. This hybrid approach can take the advantages of both types of numerical methods and avoids their shortcomings for fracturing process simulation and domain effects, respectively. In this paper, we present the hybrid approach for the stress, displacements, and fracturing processes at sequential excavation and heating steps of the in situ heater test as a predictive modelling, the formulation of the fracturing models and the predictive results. Two sections of borehole depth, 0.5 m and 1.5 m below the tunnel floor are considered. The pillar area is modelled with the FRACOD and the stress field produced by excavation and heating is transferred with corresponding boundary stresses. From the modelling results, the degree of fracturing and damage are evaluated for 120 days of heating. Dominated shear fracturing in the vicinity of the central pillar was observed from the models at both sections, but spalled area appears to be limited. Based on the modelling results, a sensitivity study for the effect of pre-existing fractures in the vicinity of the holes is also conducted, and the initiation and evolution of EDZ around the deposition holes are investigated using this particular numerical technique.

• Journal of the Korean Solar Energy Society
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• v.34 no.6
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• pp.49-56
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• 2014

Research about hybrid solar air-water heater that can make heated air and hot water was conducted as a part of improving efficiency of solar thermal energy. At this experiment, ability of making heating air and hot water was investigated and compared with traditional solar air heater and flat plate solar collector for hot water when air or liquid was heated respectively. Comparing hybrid solar air-water heater that used in this experiment to other solar air heater studied already, it has a lower efficiency at same mass flow rate. Air channel structure, fin's shape and arrangement in the air channel result in these difference then the ability of air heating need to be improved with changing these thing. In case of making hot water, performance was shown as similar with traditional system although the air channels were established beneath absorbing plate. But the heat loss coefficient was shown higher value by installing of air channel. Also the performance of hot water making was shown lower value at same liquid mass flow rate with traditional flat plate solar collector for hot water. So the necessity of performance improvement at lower mass flow rate of each heating medium can be confirmed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.99-106
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• 2012

This study presents estimation method of temperature-dependent thermal conductivity by using solution of inverse heat conduction problem. Time and depth temperature distribution data from full-scale fire test were used for estimating temperature-dependent thermal conductivity on hybrid-fiber reinforced shield tunnel lining. At short heating time, estimated thermal conductivity sharply decreased within $100^{\circ}C$. On the other hand, it reflected thermal properties of concrete and effect of steel fiber at heating time of measured maximum heating temperature. Thus arbitrary time should be determined to estimate temperature-dependent thermal conductivity in time zone of measured maximum heating temperature. Estimated temperature-dependent thermal conductivity is similar to results of other study.

• Journal of the Korean Solar Energy Society
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• v.34 no.3
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• pp.115-121
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• 2014

With increment on interesting about improving renewable energy efficiency, many research have been conducted and the research about hybrid air-water heater using solar energy that can make heating air and hot water has been conducted also. In this experiment, the temperature difference and thermal efficiency were investigated when two heating medium(air and liquid) was working simultaneously. As a result, thermal efficiency showed 44% to 88% when these heating medium was working simultaneously depending on operation condition and it is better than traditional solar collector. Also possibility of application into building equipment also was confirmed based on temperature and thermal efficiency. But necessity of additional studies about proper operation condition according to purpose of use and heat load was confirmed because change of thermal efficiency by air velocity and flux of liquid was shown a huge difference.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.4
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• pp.320-326
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• 2019

Recently, the application of atmospheric plasma technology in air filtration is increasing. Sterilization by an atmospheric plasma device is very effective. However, ozone gas, which is generated during atmospheric plasma formation, poses a hazard to human health. To reduce the ozone gas during plasma discharge, we fabricated a one-plate hybrid plasma discharge device with a heating element, which can decompose ozone gas effectively by a simple heating action. In this study, we evaluated the plasma discharge characteristics and ozone concentrations with various Ar flow rates and temperatures. With increasing Ar gas flow rate, the ozone concentration and spectrum intensity increased till an Ar gas flow rate of 60 sccm, and decreased thereafter. When discharged in high temperature, the ozone concentration and spectrum intensity decreased. Further, to evaluate the state of the treated surface under various plasma discharge and heating conditions, we measured the variation in the contact angles on the surface. Regardless of the temperature, the contact angle increased with increasing discharge voltage. However, the contact angle increased when discharged at high temperature.