• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.38-43
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• 2009

Reactors are connected with capacitors to passive filter circuits for reducing harmonics caused by power conversion application. This passive filter frequently gets out of order by voltage and current stress. Especially filter reactor has too much voltage harmonics components, its trouble rate is higher than capacitor. In this paper, we analyzed voltage and current of reactor and capacitor used for passive filter by simulation and measurement. If reactor has a tolerance on variation of reactance value, series resonance frequency is different from originally filter design frequency and parallel resonance can be generated at the close point of the former. Because filter absorbs harmonic component of non-linear load, much of harmonic voltage has been impacted on reactor.

• Journal of The Korea Institute of Healthcare Architecture
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• v.14 no.2
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• pp.43-51
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• 2008

Rehabilitation sports center is one of the sports center for the disabled that offers and operates programs to live with ordinary people through activities including various sports. This center must offer an environment that users be able to lead an sports activity by a removing physical and psychological obstacle. But most centers get in trouble using facilities that are so excessive or partly negative. Because, this center is offering a physical environment that absents correct comprehension of a standard plan and circulations of disabled. To takes part in physical exercise programs actively and encourages living sports activities, this study, will analyze circulations of disabled in accommodation and propose considerations at planning of rehabilitation sports center.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.360-365
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• 2007

This work is concerned with the topology optimization of three-dimensional cooling fins or heat sinks. Motivated by earlier success of the Internal Element Connectivity Method (I-ECP) method in two-dimensional problems, the extension of I-ECP to three-dimensional problems is carried out. The main efforts were made to maintain the numerical trouble-free characteristics of I-ECP for full three-dimensional problems; a serious numerical problem appearing in thermal topology optimization is erroneous temperature undershooting. The effectiveness of the present implementation was checked through the design optimization of three-dimensional fins.

• Biomolecules & Therapeutics
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• v.19 no.3
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• pp.274-281
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• 2011

Pharmacological approaches have been included in conventional medical treatment for insomnia or sleep disorders. However, long-term use of frequently prescribed medications can often lead to habituation, critical withdrawal symptoms and/or side effects. Some individuals with insomnia or trouble sleeping have used complementary and alternative medicine (CAM) therapies to treat their conditions. Recently, CAMs or herbs have been attractive alternative medications to many patients with sleep disorders who may be averse to using conventional drugs. We reviewed the most widely available sleep-promoting herbs commonly used in the western and oriental countries.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.412-414
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• 2009

In recent times, starting up polymer electrolyte membrane fuel cells(PEMFC) in sub-zero condition is a great challenge of fuel cell electric vehicle(FCEV). The water produced in a cathode during PEMFCs operate. The water changes into the form of solid/ice in sub-zero temperatures and this makes trouble in PEMFC cells. Voltage of PEMFC drops and cold startup is failed. This paper describes an experimental study on the effect of thermal cycle to degradation of MEA in PEMFC.

• Journal of KSNVE
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• v.5 no.4
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• pp.503-514
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• 1995

In the case of performing experimental modal analysis(EMA) and finite- element analysis(EFA) for a whole structure of automotive body that is composed of many complex parts, a trouble may arise from the calculation time, the capacity of memory in computers and the experimental conditions, etc. In this paper, for the vibrational analysis of automotive body model, the efficient modal synthesis method by means of dividing the whole structure into two parts and performing EMA and FEA for each part is studied. In addition, the method based on Lagrange interpolation is proposed for approximating rotational degrees-of-freedom information and linking FEA with EMA. In result, by measuring translational degrees-of-freedom information of only few points and adopting only few modes, the linking method based on Lagrange interpolation turned out to be efficient and accurate in the low frequency range.

• Journal of KSNVE
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• v.1 no.2
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• pp.129-140
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• 1991

The boiler feed pump located at a power plant has been experienced a severe vibration since the plant began to service in early 1980. The research is focused on the field measurement and implementation of simple signal processing techniques in order to provide realistic and effective solution which could be implemented into the plant. Based on the root cause analysis for the trouble-making pump system, the driving part gear in the fluid coupling system is identified as a potential source. The followed verification test confirms the analytical result. The test result shows that vibration reduction obtained after the gear replacement reaches up 15.8 dB, which is 1/6 times of the vibration level compared to that of the troble-making pump. The measured vibration level of the pump satisfies the manufacture criteria and guarantees the smoothed operation.

• Journal of Mechanical Science and Technology
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• v.18 no.11
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• pp.2049-2057
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• 2004

In this study, the combustion characteristics and durability of a diesel engine using emulsified fuel was investigated. Water was used in oil type emulsified fuel. In order to understand the effect of emulsified fuel in a wide range of engine running conditions, D-13 mode was selected as a test condition, and a durability test was included to understand the long-term effect of water. Combustion pressure in a cylinder, exhaust emissions, specific fuel consumption, sound level and maximum torque were measured. NOx and PM were simultaneously reduced and the specific fuel consumption was increased and decreased at low and high loads, respectively. There was no trouble and any damage on the parts of the cylinder during a 500 hour durability test.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.376-379
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• 2006

In this paper, stack voltage monitoring module is developed which monitor cell voltage of the fuel cell stack and transfer it to the main controller for monitoring fault and stopping drive when the trouble is happened in the fuel cell stack. Especially, the circuit, for monitoring each cell voltage of several hundreds cells in stack, is designed and analyzed. The connector is also developed for making wire harness simple and low cost because wire harness is complicated when the cells are connect each monitoring circuit.

• Journal of the Korean Professional Engineers Association
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• v.33 no.4
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• pp.44-47
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• 2000

Recently number of reinstrumentation projects in the process plants has grown to meet the needs to modernize or upgrade the exsisting control systems in a bid to boost productivity and quality. Design, installation and start-up of these process automation systems can be successful and trouble-free only if decision points are addressed properly. The critical decision points are encountered from tile design through the start-up phases of implementing a modernization project and discussed extensively here on a practical basis. Key points are ;to assign a project manager out of the plant instrument engineers for him to organize and lead a project team. ;to follow three critical steps in designing and implementing. :to think ahead of the critical steps and to induce a positive cooperation from all level of participants in the effort to prevent possible schedule delays.