• 지식경영연구
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• 제14권5호
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• pp.1-14
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• 2013

This paper is aimed at investigating the factors to grow the new technology based firm(NTBF), K-MAC. NTBFs need an environment in which novelty is encouraged, employees find work meaningful and controllable, learning is incorporated into work, ideas and process improvements are implemented and a balanced focus of the internal and external to the company is fostered. With collaboration between industry and academia, Lynda Aiman-Smith made an instrument of VIQ(Value Innovation Quotient), which is consist of 9 factors, 33 items. VIQ Results can help the company to develop a better understanding of the organization's culture, and its formal subgroups. That is to identify subcultures in the organization, to diagnose potential problems or inhibitors of innovation, to identify organizational strengths for innovation and set a quantitative baseline. Using the VIQ,K-MAC analysed the subculture of innovation potential capability. K-MAC organized the COP(community of practice) with the young employees' participation and try to solve the real problem in the working place. This paper explained the diverse growing trajectory through the TPM concept and suggest for the future strategy.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.64-67
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• 2004

The klystron-modulator(K&M) system of the Pohang Light Source(PLS) had been supplying high power microwaves for the acceleration of 2.5 GeV electron beams since October 2002. There are 12 sets of K&M systems to accelerate electron beams to 2.5GeV nominal beam energy. One module of the K&M system consists of an 80 MV S-band (2856 MHZ) klystron tube and the matching 200 MW modulator. In order to obtain electron beam of the consequently stability for linac, the pulse-to-pulse beam voltage regulation is less than $+/-0.5\%$. To get the reliable stability of the modulator which is less than $+/-0.5\%$, a charging section is improved in a modulator which has been operated with inverter power supply.

• KIEAE Journal
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• 제15권3호
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• pp.57-63
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• 2015

Purpose: Ground source heat pump system has been attracted in the horticulture industry for the reduction of energy costs and the increasing of farm income. Even though it has higher initial costs, if it uses in combination with heat storage, it is able to reduce the initial costs and operate efficiently. In order to have significant effect of heat storage type ground source heat pump system, it is required to design the capacity considering various conditions such as energy load pattern and operating schedule. Method: In this study, we have designed heat storage type ground source heat pump system in 5 cases by the operating schedule, and examined the system to find the most economic and having superb performance regarding the system COP(Coefficient of Performance) and energy consumption, using dynamic energy simulation, TRNSYS 17. Result: Conventional ground source heat pump system has lower energy consumption than heat storage type, but following the result of LCC(Life Cycle Cost) analysis, the heat storage type was more economic due to the initial costs. In addition, it has the most efficient performance and energy costs in the case of the smallest heat storage time.

• 설비공학논문집
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• 제17권1호
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• pp.47-55
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• 2005

An experimental study has been peformed to develop a scheme for fault detection and diagnosis(FDD) in a vapor compression refrigeration system. This study is to analyze fault effect on the system performance and to find efficient diagnosis rules for easy determination of abnormal system operation. The refrigeration system was operated with a variable speed compressor to modulate cooling capacity. The FDD system was designed to consider transient load conditions. Four major faults were considered, and each fault was detected over wide operating load range by separating the system response to the load change. Rule-based method was used to diagnose and classify the system faults. From the experimental results, COP degradation due to the faults in a variable speed system is severer than that in a constant speed system. The method developed in this study can be used in the fault detection of refrigeration systems with a variable speed compressor.

• 설비공학논문집
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• 제17권1호
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• pp.71-81
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• 2005

The main objective of the present study is to investigate the performance characteristics of a ground-source heat pump(GSHP) system with a 130 m vertical and 62 mm nominal diameter U-tube ground heat exchanger. In order to evaluate the performance analysis, the ground-source heat pump connected to a test room with $90\;m^2$ floor area in the Korea Institute of Construction $Technology(37^{\circ}39'N,\;126^{\circ}48'E)$ was designed and constructed. This ground-source heat pump system mainly consisted of ground heat exchanger, indoor heat pumps and measuring devices. The cooling and heating loads of the test room were 5.5 and 7.2 kW at design conditions, respectively. The experimental results were obtained from July 2, 2003 to July 1, 2004. The cooling and heating performance coefficients of the system were determined from the measured data. The average cooling and heating COPs for the system were obtained to be 4.90 and 3.96, respectively. The temperature variations in ground and the ground heat exchanger pipe surface at different depths were also measured.

• 설비공학논문집
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• 제10권6호
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• pp.753-762
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• 1998

A domestic refrigerator is composed of many components such as a compressor, evaporator, capillary tube, and the cabinet which plays a great role on the cycle performance, even if it is not the basic component part in the cycle. Recently, the restriction policy on the energy-saving and environmentally friendly refrigerator is reinforced in our nation as well as developed countries. Therefore, in this paper, cycle simulations and experiments were carried out ito understand the characteristics of the cycle performance using CFC 12, HFC 134a, and HC 600a and to know how changes in UA(overall heat transfer coefficients$\times$ heat transfer area) of evaporator, the position displacement of compressor, and the rpm of fan in the freezing room which has influence on the cycle performance. The result shows that the quantitative values of simulation and experiment are not coincident, but their trend is similar. When HFC 134a and HC 600a were used without the change of design in refrigerator used CFC 12, the performance of system in HC 600a is 30% lower, and the case of HFC 134a is 10% lower than that of CFC 12 on freezing temperature.

• 설비공학논문집
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• 제23권6호
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• pp.392-399
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• 2011

Ground-coupled heat pump(GCHP) systems have been shown to be an environmentally-friendly, efficient alternative to traditional cooling and heating systems in both residential and commercial applications. Although some work related to performance evaluation of GCHP systems for commercial buildings has been done, relatively little has been reported on the residential applications. The aim of this study is to evaluate the cooling and heating performances of a vertical GCHP system applied to an artificial detached house($117\;m^2$) in Seoul. For this purpose, a typical design procedure was involved with a combination of design parameters such as building loads, heat pump capacity, borehole diameter, and ground thermal properties, etc. The cooling and heating performance simulation of the system was conducted with different prediction times of 8760 hours and 240 months. The performance characteristics including seasonal system COP, average annual power consumption, and temperature variations related to ground heat exchanger were calculated and compared.

• 설비공학논문집
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• 제23권6호
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• pp.421-429
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• 2011

Experimental and theoretical studies on cooling performance of two-channel thermoelectric air-cooling system in parallel flow are conducted. The effects of operating temperature to physical properties of thermoelectric module (TEM) are experimentally examined and used in the analysis of an air-cooling system considering thermal network and energy balance. The theoretical predicted temperature variation and cooling capacity are in good agreement with measured data, thereby validating analytic model. The heat absorbed rate increases with increasing the voltage input and decreasing thermal resistance of the system. The power consumption of TEM is linearly proportional to mean temperature differences due to variations of the physical properties on operation temperature of TEM. Furthermore thermal resistance of hot side has greater effects on cooling performance than that of cold side.

• 설비공학논문집
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• 제21권3호
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• pp.131-139
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• 2009

The simulation of refrigeration cycle is important since the experimental approach is costly and time-consuming. The present paper focuses on the simulation of a refrigeration cycle equipped with a capillary tube-suction line heat exchanger(SLHX), which is widely used in small vapor compression refrigeration systems. The present simulation is based on fundamental conservation equations of mass, momentum, and energy. These equations are solved through an iterative process. The non-adiabatic capillary tube model is based on homogeneous two-phase flow model. This model is used to understand the refrigerant flow behavior inside the non-adiabatic capillary tube. The simulation results show that both of the location and length of heat exchange section influence the coefficient of performance (COP).

• 설비공학논문집
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• 제21권3호
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• pp.149-156
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• 2009

A small-scale thermoelectric cooling system was built in an effort to enhance the performance of the refrigeration system by utilizing the water-cooled jacket which was attached to the hot side of the thermoelectric module. Considered design parameters for the water-cooled jacket were the geometry of the flow passage inside the jacket and the flow rate of cooling water. The higher flow rate of cooling water in the jacket resulted in a better performance of the refrigeration system. The increase in the number of channels for water flow passage inside the cooling jacket also showed significant improvement on the performance of the thermoelectric cooling system such as the cooling capacity and the COP of the refrigeration system.