• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권11호
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• pp.622-627
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• 2002

The power comparison techniques have implemented power measurements, in which a power comparator is used to balance ac against a dc power obtained from known values. The developed power standard system using the comparison techniques consists of dc sources, ac source, control switches, resistive voltage dividers, resistive shunts and a power comparator. The total uncertainty of the power standard system was proved by analysis of the component instruments. Its expanded(k=2) uncertainty is evaluated to be less than 30 uW/VA at unit power factor and 42 uW/VA at power factor 0.5

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.557-560
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• 2008

Window system is an essential component for ventilation, lighting, and thermal environment in buildings. However, window system has the lowest insulation performance and may cause high energy consumptions, if it is not properly designed. Thus, performance of window systems play an important role in built environment. This study proposes a new window systems for balcony, which has double vents and analyses the thermal performance using an intergrated simulation method with Therm 6.1 and Widow 6.1. The result shows higher U-factor than conventional window systems. It is expected that the double vent window system can increase thermal performance and save energy in apartment houses.

• 설비공학논문집
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• 제19권1호
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• pp.10-18
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• 2007

The purpose of this study is to develop an user-friendly computer program which can analyze the thermal performance of high-rise curtain wall. In this study, the sub-routines for FVM SOLVER, HIGH-RISE CONDITION CALCULATION, AUTOMATIC SPECIFICATION BOUNDARY/MESH, MATERIAL DATABASE, and GRAPHICAL CONDENSATION/U-FACTOR OUTPUT were developed by using Visual Basic. The curtain wall heat conduction simulation results of program showed good agreement with those of FLUENT and THERM. The minimum and maximum relative error rates were 3.17 and 9.68% compared to other software.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권8호
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• pp.536-543
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• 2000

The photovoltaic power generation system has a great future as clean energy instead of fossil fuel which has many environmental problems such as exhausted gas or air pollution. In a utility interactive photovoltaic generation system, a three-phase inverter is used for the connection between the photovoltaic array and the utility. This paper present a three phase inverter for photovoltaic power system with current controller, voltage controller, PLL Control system and the Phase detector of Interactive Voltage by using dq transformation. The proposed inverter system provides a sinusoidal ac current for domestic loads and the utility line with unity power factor.

• 조명전기설비학회논문지
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• 제29권5호
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• pp.41-49
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• 2015

In this paper, we studied an optimal design and efficiency improvement of the BLCD motor used in home electronic appliance. The number of stator slots is chosen depending on the rotor poles, phase number, and the winding configuration. In general, a fractional slots/pole design is preferred to minimize cogging torque. To reduce the winding resistance, we reduced the coil length and we improved the coil space factor. We proposed three types of stator slot shape design for the optimal BLDC motor design. One of them, U-type slot shape is a best optimal design, it proved by the simulated and tested. Optimal design of essential parameters aiming at high winding factor are presented to create for a high-quality system implementation. Design analysis is verified by testing and building a prototype motor.

• 통합자연과학논문집
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• 제5권3호
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• pp.157-162
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• 2012

Measurement error is one of main source of error in survey. It is generally defined as the difference between an observed value and an underlying true value. An observed value with error may be expressed as a function of the true value plus error term. In some cases, the measurement error variance may be also a function of the unknown true value. The error variance function can be rewritten as a function of true value multiplied by a scale factor. This research explore methods for estimation of the measurement error variance based on the data from complex sampling design. We consider the case in which the variance of mesurement error is a linear function of unknown true value, and the error variance scale factor is small. We applied our results to the U.S. Third National Health and Nutrition Examination Survey (the U.S. NHANES III) data for empirical analyses, which has replicate measurements for relatively small subset of initial respondents's group.

• 기술혁신연구
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• 제12권1호
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• pp.115-134
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• 2004

In this paper, we tried to find the bottleneck factors of firms' innovative activities using the KIS (Korea Innovation Survey) 2002 data. Employing the method of factor analysis, we identified five bottleneck factors of innovative activities: organizational bottleneck factor, innovative bottleneck factor, economic bottleneck factor, supply-chain bottleneck factor, and market-environment bottleneck factor. Using regression analysis which includes the five bottleneck factors, industry characteristics variables (market concentration, technological opportunity, appropriability), and other control variables, we found (1) that all the five bottleneck factors are negatively related with innovative activities, (2) that technological opportunity and appropriability conditions are positively related with innovative activities, (3) that there is an inverted-U relationship between market concentration and innovative activities, and (4) that firm size has no significant influence on firms' innovative activities.

• 대한한의진단학회지
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• 제13권1호
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• pp.81-88
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• 2009

Purpose : To find out correlation between the Vocal indicators and the 'Buzhongyiqi-Tang questionnaire'. Method : The 'Buzhongyiqi-Tang questionnaire' is given to 83 healthy adults and collected their voice /a/ /e/ /i/ /o/ /u/. Analyze mean values of each factors of the Vocal indicators and the 'Buzhongyiqi-Tang questionnaire'. Conclusions : R square values of /i/ sound in factor 1 and factor 3 of 'Buzhongyiqi-Tang questionnaire' are noticeably high. The value of vocal diagnosis index F0, Fundamental Frequency, in Factor 1 and factor 3 of 'Buzhongyiqi-Tang questionnaire' are considerable. The research has shown conclusively that there is a link between The value of vocal diagnosis index F0 and Factor 3, lung deficiency factor, of 'Buzhongyiqi-Tang questionnaire'.

• 한국정보시스템학회지:정보시스템연구
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• 제18권1호
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• pp.145-157
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• 2009

If industrial disasters happen at workplace, work's desires of workers and business activities may be dispirited. Especially, industrial disasters frequently happen in the field of heavy and chemical industry companies. According to report of the korea occupational safety and health agency(KOSHA), damage due to industrial disasters is more 5 times than losses due to industrial strifes. Thus, in these manufacturing companies, a safety management field for preventing industrial disasters is emerging as an important factor of business activities. This paper proposes an industrial disaster prediction model for safety management and also implements industrial safety management system(after this, is called as u-Safety system) based on the proposed model using ubiquitous computing technologies like USN(ubiquitous sensor networks) which are given much attention among recent information technologies. The implemented system is successfully operating in the shipbuilding division of 'H' companies.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.372-375
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• 2007

750kW gearless type wind turbine, named U50, is developed by UNISON in Korea. The newly developed wind turbine should be evaluated the power curve and the estimated annual energy production by following international standard to verify the power performance characteristics. This paper shows the test and evaluation procedure according to IEC 61400-12-1 which specifies a procedure of measuring the power performance characteristics of a single wind turbine and applies to the testing of wind turbines of all types and sized connected to the electrical power network. And this paper also shows the power performance characteristics for U50 wind turbine which is determined in accordance with IEC regulation.