• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.4
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• pp.238-243
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• 2006

This paper presents novel ignition method for automotive 35W metal halide discharge lamp electronic ballast. At this study, the novel method of ignition is developed to reduce costs and size of the ballast. By use of the novel method, the voltage needed in ignition is decreased, which result in use of the lower voltage rating power devices compared with conventional method and product compactness was achieved by deleting a circuit generating negative voltage needed in ignition at an conventional circuit. In terms of luminosity, color rendering, light efficiency(lm/W) and lifespan, the metal halide lamp is superior to, but unlike halogen lamp, it have more complicated transient characteristics to reach its steady state than the conventional halogen lamp. Therefore, in this paper, the electronic ballast was designed such that the metal halide lamp could be optimized for the automotive, by applying a method of microcontroller-based digital control. The results of the proposed system is verified through various experiment results.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.587-588
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• 2010

The maximum output torque developed by the machine is dependent on the allowable current rating and maximum voltage that the inverter can supply to the machine. Therefore, to use the inverter capacity fully, it is desirable to use the control scheme considering the voltage and current limit condition, which can yield the maximum torque per ampere over the entire speed range. This controller is controlled speed using artificial intelligent PI(AIPI) controller. Also, this paper is proposed control of maximum torque per ampere(MTPA) of induction motor. The performance of the proposed induction motor drive with maximum torque control using AIPI controller is verified by analysis results at dynamic operation conditions.

• Journal of Biosystems Engineering
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• v.35 no.2
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• pp.69-76
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• 2010

This study was conducted to develop an index of fuel consumption to rate agricultural tractors by their fuel efficiencies. The fuel consumption index consisted of two components: basic and operational indexes. The basic index is to consider an average amount of fuel consumed by engine when it transmits 20 and 100% of the rated power. The operational index is to consider the fuel consumed by tractor for typical field operations: plowing, rotavating, and the remains. The equations and procedures to obtain these indexes were proposed. The method and fuel consumption rate to classify tractors into 5 grades were also proposed. The best 15% of the tractor models were rated as the first grade, 20% as the second grade, 30% as the third grade, 20% as the fourth grade, and 15% as the fifth grade in order of fuel efficiency. Using the fuel consumption index, the classification was conducted on 143 tractor models tested at the National Institute of Agricultural Engineering from 2000 to 2007. The proposed 5-grade system of classification using the fuel consumption index could be used to rate the fuel efficiency of 20-100 kW tractor models produced over past 10 years in Korea.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.549-554
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• 2013

For the past years, higher power rating 2 stroke super long stroke diesel engines having more than 8 cylinders and larger cylinder bore are installed mainly on very large containerships to save on fuel consumption. However, these engines are prone to X-mode vibration due to $2^{nd}$ node torsional vibration or the X-type moment, particularly because of the increase in total length and height. Recently, cases of excessive X-mode vibration often occurred on engine's major components. This vibration is manifested also as secondary vibration causing failure in engine-mount large structures. This study investigated the excitations caused by the $2^{nd}$ node propulsion shafting torsional vibration that influence X-mode vibration of the main engine and practical countermeasures are proposed. An 8RT-82RT-flex 8 cylinder engine and 11S90S-ME 11 cylinder engine for a container ship was used as research model.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.43.1-43.1
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• 2011

The detail simulation modeling of fully-fed induction generator is investigated through PC based MATLAB/Simulink environment. Generator's stator currents are controlled by indirect vector control method. In this method, generator side converter controls the maximum excitation (air gap flux) by stator d-axis current and controls generator torque by stator q-axis current. Induction generator speed is controlled by tip speed ratio (TSR) upon the wind speed variations in order to generate the maximum output power. The generator torque model is specified as a 3-blade wind turbine with rating, then, the model is simulated under normal operating condition and three different fault conditions. The matlab model designed for fully-fed induction generator based wind farm provides good performance under normal and grid fault conditions. It provides good results for different pwm techniques and fault conditions except the single-phase line to ground fault, which should be verified with real time data from wind farms.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06c
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• pp.191-194
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• 2011

문서를 이루는 단어들의 빈도수가 지수법칙(power law)를 따른다는 지프의 법칩(Zipf's law)이 있다. 이러한 단어분포를 고려하여 문서의 토픽을 찾아내는 기계학습법이 디리쉴레 프로세스(Dirichlet process) 이다. 이를 발전시켜서 데이터의 잠재 요인(latent factor)들을 베이즈 확률모델에 기반한 샘플링 바탕으로 찾는 방법이 인디언 뷔페 과정(Indian buffet process) 이다. 우리는 25가지의 특징(feature)들에 대한 점수(rating)들이 볼드(blood oxygen dependent level) 신호와 함께 주어지는 PBAIC 2007 데이터에 주성분 분석법(principal component analysis)를 적용했다. PBAIC 2007 데이터는 비디오 게임을 수행하며 기능적뇌영상(functional magnetic resonance imaging, fMRI) 촬영을 하여 얻어진 공개데이터이다. 우리의 연구에서는 주성분 분석법을 이용하여 10개의 독립 성분(independent component)들을 찾았다. 그리고 1.75초 마다 촬영된 BOLD 신호와 10개의 고유벡터(eigenvector)들간의 내적을 취하여 가중치(weight)를 구하였다. 성분들의 가중치를 낮은 순서로 정렬함으로써 각 시간마다 주도적으로 영향을 미치는 성분들을 알아낼 수 있었다.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.61-68
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• 2018

This paper is elaborates on the pure sine wave single phase inverter of 500W level which is driven by battery. The inverter is structured to raise the battery voltage to 400V by using the push-pull topology, and by using H-bridge with the high voltage, it outputs common 220VAC. This topology is utilized to use the power semiconductor device in order to design and manufacture the inverter of 500W at input voltage rating of 12VDC. As a result, the efficiency exceeds 90% in partial sections, but on average, the efficiency is approximately 89.5%, and as for output voltage, frequency fluctuation range and THD, the result can be less than ${\pm}5%$.

• The Journal of Korean Obstetrics and Gynecology
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• v.28 no.4
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• pp.31-45
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• 2015

Objectives : The purpose of this study is to examine the relationship between the symptoms of primary dysmenorrhea and pulse energy of Chon, Gwan and Cheok. Methods The subjects of this study who had certain range of dysmenorrhea symptom. The degree of dysmenorrhea were assessed by Visual Analog Scale (VAS), Multidimensional Verbal Rating Scale (MVRS), Cox Menstrual Symptom Scale (CMSS) and measured by 3D Blood Pressure Pulse Analyzer(3D-MAC) tests at menstruation start date. Data analysis included descriptive statistics and multiple linear regression using the SPSS/WIN 18.0 program. Results : The induced results are as follows;The induced results are as follows 1. There were no significant relationship between the pulse energy and the sum values of VAS, MVRS and checking part of severity of CMSS. 2. The frequency domain of CMSS were significantly associated with pulse energy. 3. In linear regression models, the model of Left Chon had the especially highest value of explanatory power. (R ² = 0.517) Conclusions : The pulse energy changes are related to the symptoms of primary dysmenorrhea.

• International Journal of Air-Conditioning and Refrigeration
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• v.6
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• pp.36-44
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• 1998

R-410a and R-407c which have the best potential among R-22 alternatives were tested as drop-in refrigerants against a set of R-22 baseline tests. The performance evaluations were carried out in a psychometric calorimeter test facility using the residential spilt type air conditioner under the ARI rating conditions. Except the lubricant and hand-operated expansion valve, the other parts of the air conditioner were the same with the commercial system. Performance characteristics were measured; compressor power, capacity, VCR, mass flow rate and COP. The tests showed that R-407c can be directly charged into the current refrigeration system because its vapor pressure and other thermochemical properties are similar to those of R-22. However, it is required to change the volume flow rate of compressor in order to achieve the volumetric capacity of R-22. This results from its relatively small VCR and capacity. Meanwhile, R-410a has vapor pressure values too high to be substituted for the current system and this resulted relatively low COP of R-410a compared to that of R-22.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.82-91
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• 1997

R-410a and R-407c witch have the best potential among the substances being considered as R-22 alternatives were tested as "drop in" refrigerants against a set R-22 baseline tests for comparison. The performance evaluations were carried out in a psychrometric calorimeter test facility using the residential split-type air conditioner under the ARI rating conditions. Other than the use of different lubricant and a hand-operated expansion valve, one of the commercial systems was selected for the experiment. Performance characteristics were measured; compressor power, capacity, VCR, mass flow rate and COP. The tests showed that R-407c can be directly applied to the existing refrigeration system because of its similar vapor pressure and other thermopysical properties with those of R-22. However, it required change to the volume flow rate of compressor in order to achieve the similar performance with R-22 because of its relatively small VCR and capacity. Meanwhile, R-410a has too high a vapor pressure to be applied to the existing system and this feature results in relatively low COP of the system compared to that of R-22. But this could be improved by changing compressor design considering R-410a's relatively high VCR and capacity compared to those of R-22.