• 연구논문집
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• s.27
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• pp.75-86
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• 1997

Combined cycle power plant is a system where a gas turbine or steam turbine is used to produce shaft power to drive a generator for producing electrical power and the steam from the HRSG is expanded in a steam turbine for additional shaft power. Combined cycle plant is a one from of cogeneration. The temperature of the exhaust gases from a gas turbine ranges from $400^\circC$ to $600^\circC$, and can be used effectively in a heat recovery steam generator to produce steam. Combined cycle can be classed as a "topping(gas turbine)" and a "bottoming(steam turbine)" cycle. The first cycle, to which most of the heat is supplied, is called the topping cycle. The wasted heat it produces is then utilized in a second process which operates at a lower temperature level and is therefore referred to as a "bottoming cycle". The combination of gas/steam turbine power plant managed to be accepted widely because, first, each individual system has already proven themselves in power plants with a single cycle, therefore, the development costs are low. Secondly, the air as a working medium is relatively non-problematic and inexpensive and can be used in gas turbines at an elevated temperature level over $1000^\circC$. The steam process uses water, which is likewise inexpensive and widely available, but better suited for the medium and low temperature ranges. It, therefore, is quite reasonable to use the steam process for the bottoming cycle. Only recently gas turbines attained inlet temperature that make it possible to design a highly efficient combined cycle. In the present study, performance analysis of a dual pressure combined-cycle power plant is carried out to investigate the influence of topping cycle to combined cycle performance.

• Journal of Biosystems Engineering
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• v.34 no.4
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• pp.220-227
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• 2009

In the process of oyster mushroom production, loading work of culture medium needs the most intensive labor power. Therefore, development of culture medium machine causes to reduce the manpower and cost. The main objective of this study is to develop the culture medium loading machine and investigate the optimal operation conditions and to evaluate the economic value of the machine. The results are summarized as follows: 1. Optimum transporting velocity of the conveyor was 0.61 m/s 2. Optimum speed of blower was 3183 rpm at the transporting velocity of 0.61 m/s with the loading quantity of 3.41 t/hr 3. Recommendable opening area ratio of pressure controller was 1/2 at the blower speed of 3183 rpm and the transporting velocity of 0.61 m/s 4. The break even point resulted in $240\;m^2$ of cultivating area compared to the method of with portable workbench, and $350\;m^2$ of cultivating area compared to the method of with a tractor and a truck.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.40
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• pp.351-360
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• 1996

Korean construction companies are now in very difficult situation due to the recent construction accident, opening of domestic market, the advent of boundless competition period in WTO, etc .Introduction of quality management system is quite urgent in order to strengthen our international competitiveness through the superiority of quality and foster the long term growth of organization. Substantially, many companies are proceeding with or completed the introduction of quality management system but small and medium sized construction companies have difficulties due to lack of money and man power. In this paper, five stage procedures, which can be efficiently applied to introduction and operation of qualify management system, have been suggested to help the minor construction companies which want to adopt the quality management system. This study is considered to be helpful for the companies which will introduce quality management system.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1634-1636
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• 2001

We have developed the global assessment system for medium voltage power cable systems. Our purpose of diagnostic activity is the economic discrimination and maintenance of bad cables which is likely to cause cable system failure. We have atapted the Voltage Decay Method to construct the power cable assessment system for our diagnostic purpose. From the field application test results, we have concluded that our system is successful and convenient for the discrimination and maintenance of the damaged cables economically.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.244-245
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• 2013

This paper proposes a control algorithm for permanent magnet synchronous generator with a back-to-back three-level neutral-point clamped voltage source converter in a medium-voltage offshore wind power system under unbalanced grid conditions. The proposed control algorithm particularly compensates for the unbalanced grid voltage at the point of common coupling in a collector bus of offshore wind power system. This control algorithm has been formulated based on the symmetrical components in positive and negative rotating synchronous reference frames under generalized unbalanced operating conditions. Instantaneous active and reactive power are described in terms of symmetrical components of measured grid input voltages and currents. Negative sequential component of ac input current is injected to the point of common coupling in the proposed control strategy. The amplitude of negative sequential component is calculated to minimize the negative sequential component of grid voltage under the limitation of current capability in a voltage source converter. The proposed control algorithm makes it possible to provide a balanced voltage at the point of common coupling resulting in the generated power of high quality from offshore wind power system under unbalanced network conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.767-770
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• 2006

To predict vibrational energy density of simple structural-acoustic coupled systems in medium-to-high frequency ranges, Power Flow Finite Element Method(PFFEM) is used, and PFFEM sofiware, PFADS has been developed for the vibration predictions and analysis of coupled system structures in medium-to-high frequency ranges. However, it needs to consider vibro-acoustic coupled analysis to get more accurate results. Prior to implement vibro-acoustic coupled analysis functions in PFADS, research on vibro-acoustic coupled analysis using PFFEH is performed for simple models. These predictions include the indirect transmission path associated, and also the direct transmission path, and the formulation is extended to structural system model by using appropriate modifications to structural-acoustic and acoustic-acoustic joint matrices. Concerning the waves in plate and acoustic, it is possible to calculate the structural-acoustic full matrix of a model using PFFEM, and the formulations developed are implemented for two rooms surrounded by plates.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.2 no.1
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• pp.133-151
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• 2007

In the era of 21st new century. reinforcement of regional competitiveness by establishing innovation system is taking its place of main small and medium sized enterprise policies in major developed countries. The model of regional balanced development for promoting small and medium sized enterprise is a main frame of governmental small and medium sized enterprise policies. which complements national innovation process. And in the level of local area, the model is regional network system, molded in the process of induction, application, modification, proliferation of new technologies and knowledge by local businessman and innovators. This study focused on the strategy development for small and medium sized businesses to increase local competitive power, in terms of regional balanced development. In order to find the real problems and improvement alternatives for local competitive power, this study both reviewed the common strategies and action programs advanced in developed countries for small businesses, and did research on the current economic conditions in local area. Based on the lessons from foreign cases and the analysis of the current situations in small business in local area, the study suggested the model of regional balanced development for promoting small and medium sized enterprise including formation of innovation network system through the invitation of leading firms in the area, industry-university partnerships, and development and attraction for small and medium sized businesses.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.441-442
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• 2013

This paper deals with 100kW IPMSM drive inverter for Midium Duty Electric Car. First, it introduces about hardware structure of inverter. Then performance of IPMSM drive system is confirmed through experiments.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1663-1664
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• 2008

Many years ago, most of thermal power plants built in this country were of subcritical pressure, of medium or small size, of constant pressure operations and of drum type steam generators with circulation type boilers. But, nowadays almost all of them were of high efficiency, of supercritical pressure, of big capacity, of sliding pressure operations, and of once through type steam generators. Presently built once through boilers introduce turbine bypass systems to variable pressure operation which eliminates unexpected materials in boiler tube during startup, minimizes fuel loss by short startup period and eventually improve both total efficiency and power system stability.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.561-565
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• 2006

The paper presents a method of assessing the adequate tapaclty of photovoltaic generation systems for public buildings based on analysis of load variation patterns of customers. When PV systems are installed for supplying power for the customer load, reverse power relay is required by the guideline to be installed at the point of common coupling with the power network. The suggested method analyzes daily, weekly and monthly load demand of the customer that Irishes PV system installation, and determines the appropriate rating of the PV system for preventing PV generation from exceeding the customer demand. This work is expected to support renewable energy dissemination projects of public organizations.