• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.553-555
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• 1996

This paper concerns with a method to improve the current and power waveforms of the variable speed $3{\Phi}$ AC motor system driven by the single-pulse PWM, and the current waveforms and $3{\Phi}$ power waveforms are analyzed by FFT under various running conditions. By the performance analysis through the experiments, the following results have been obtained. AC source of pseudo sine waveform can be obtained from the modulated alternating square voltage by means of the well designed LC filter. It is confirmed that current waveforms and $3{\Phi}$ power waveforms can be improved by utilizing the high order low pass LC filter than that of lower order. Especially, current waveforms and $3{\Phi}$ power waveforms tan be much improved at low frequency domain. $3{\Phi}$ power waveforms have a smatter ripple and bigger power by utilizing the high order low pass LC filter than that of lower order. Also, the running condition of $3{\Phi}$ AC motor is good at low frequency domain.

• 무역학회지
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• 제45권3호
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• pp.119-132
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• 2020

In this paper we explore the two analyses to know the urbanization effect on trade. First, the granger causality test to examine the relationship between trade and urbanization. The Granger causality test is a statistical hypothesis test for determining whether one time series is useful for forecasting another. The results indicated that the existence of a bidirectional causality running from trade to urbanization when six lags were applied. When eight lags were applied, we found unidirectional causality running from urbanization to trade. Second, gravity models were used to investigate the urbanization effect on trade. The production cost and specification are affected by the economies of scale, and the economies of scale increased as the greater geographically agglomeration. However, the gravity model to explain the bilateral trade flows ignores the urbanization variables. Therefore we added the urbanization variable represented as the geographically agglomeration into gravity model. The results show that the degree of urbanization of both countries has statistically positive effect on trade (export and import) and the bigger coefficients of trade partner's urbanization. The reason is that the trade share of industrial supplies, intermediate goods and capital goods is much higher than finished consumer goods. The urbanization is more important the improved the efficiency of production than demand market.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.121-129
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• 2011

Hydrocarbons which are the main sources of VOCs from motor vehicles are emitted not only from the engine exhaust gas but also from evaporation of the fuel in storage and supplying systems. Evaporative emissions from gasoline fuel systems could be classified by diurnal, hotsoak and running loss. Diurnal loss test procedures are different as countries. Korea introduced new evaporative regulation in 2009 with 24hour VT-shed test procedure and relaxed emission standards. The estimations on different test procedures in this study show that the new Korean regulation get a little more severe than before and the 2 day diurnal loss test of U.S. is the most severe. So the test procedures as well as the stronger standards should be considered in the next evaporative emission regulation to reduce VOCs from motor vehicles. The important parameters to affect evaporative emissions are air and fuel temperature and fuel vapor pressure. Diurnal loss increases exponentially as rising air temperature and vapor pressure. The effects of vapor pressure on running loss are different as the capacities of canisters. Tests with simulating real temperature and driving conditions show that hydrocarbons in evaporative emissions could be more than those in exhaust gas in summer season because of the higher air temperature.

• 한국균학회지
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• 제27권2호통권89호
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• pp.112-118
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• 1999

한국, 일본 그리고 미국 등지에서 수집된 Fusarium oxysporum f. sp. lycopersici의 electrophoretic karyotype(EK)을 분석하고자 CHEF-DRII pulsed field gel electrophoresis system(Bio-Rad Laboratories, Melville, NY)으로 각 공시균의 chromosome sized DNA를 분리하였다. EK 분석에 적합한 CHEF gel electrophoresis 조건을 얻기 위해 전기영동 시간 및 전압 그리고 switching interval 등의 조건을 다양하게 바꾸어 가며 실험하였다. 그 결과 국내 균주에서 $0.76{\sim}6.41\;Mb$에 달하는 $9{\sim}11$개의 chromosome sized DNA가 분리되었으며 그 total genome size는 $35.29{\sim}38.92\;Mb$ 이었다. 또한 일본과 미국 균주로 부터 $1.24{\sim}6.85\;Mb$범위의 $9{\sim}11$개의 chromosome sized DNA가 분리되었고 그 total genome size는 $35.32{\sim}43.87\;Mb$ 이었다. 이와 같이 얻어진 각 공시균주의 EK는 chromosome sized DNA의 length range 및 total genome size에서 국내 균주와 외국 균주간의 차이를 잘 반영하였다. 또한 국내 균주의 chromosomal polymorphism은 그 변이가 적어 서로 동일하거나 유사하였으며 외국 균주와 뚜렷이 다른 chromosomal DNA pattern을 나타냈다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2139-2144
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• 2008

There are eight kinds of railroad vehicles such as KTX, PP(Push-Pull), NEL(New Electric Locomotive), EL(Electric Locomotive), DL(Diesel Locomotive), CDC(Commuter's Diesel Car), VVVF(Variable Voltage Variable Frequency) and Resistance Control Car that Korail corporation presently runs, and a variety of vehicles just like EMU(Electric Multiple Unit) and DMU(Diesel Multiple Unit) currently developed and accepted are running in the near future. However, There is still no design standard of the control stand of cockpit and the same compatibility of forms and control unit arrangements for locomotive engineers because no one has tried to approach in an ergonomic way. It can cause Locomotive engineers to make errors using the machinery. when the new vehicles are adopted, The efficiency of operation will quite fall down due to the separate training of the engineers. Therefore, We'd like to improve the accuracy of manipulating the machinery used by the engineers at all times according to the design standard of ergonomic technology and safety engineering and increase the operational efficiency and the safety of railroad vehicles in order to handle the problems as quickly as we can in an emergent situation.

• 운동과학
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• 제21권2호
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• pp.231-242
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• 2012

본 연구의 목적은 운동부하검사에서 일반적으로 많이 사용하는 Bruce protocol을 이용한 최대하 운동의 대사반응, 주요 시점의 심박수 기록 및 1,200 m 달리기 기록을 이용하여 최대산소섭취량을 추정하는 모형을 개발하고 모형간 추정의 타당도를 분석하는 데 있다. 연구대상은 성인 남성 255명(1,200 m 달리기는 133명)이며 Bruce protocol을 이용하여 최대운동부하검사를 실시하였고, 3분인 1단계와 6분인 2단계 종료 시점의 대사반응을 측정하였다. 측정항목은 VO₂(㎖㎖/kg/min), VCO₂(㎖/kg/min), VE(L/min) 및 HR(bpm), HR가 150 bpm과 170 bpm에 도달하는 시간, Bruce protocol 6분과 3분 심박수 차이, 1,200 m 달리기 기록 등이었다. 신체자료와 최대하 운동 중 대사반응을 이용하여 최대산소섭취량을 산출하는 모형을 개발하기 위하여 다중회귀분석을 실시하였다. 모든 변수를 동시투입법으로 분석한 전체모형의 R은 0.642이고(p<.01) 추정의 표준오차(SEE)는 4.38 ㎖/kg/min, 변동계수(CV)는 10.8%이었으나(p<.01), 다중공선성이 나타났다. 단계별분석법으로 분석한 3분모형1과 모형2의 R은 0.341과 0.461이고, SEE는 6.05와 5.72 ㎖/kg/min, CV는 14.9와 14.1%로 나타났고(p<.01), 다중공선성이 나타나지 않았다. 6분모형1과 모형2의 R은 0.350과 0.456이었고(p<.01), SEE는 6.03과 5.74 ㎖/kg/min, 변동계수(CV)는 14.9와 14.2%로 나타났으며(p<.01), 다중공선성이 나타나지 않았다. 6분HR-3분HR 모형의 R은 0.150, HR150모형은 0.151, HR170모형은 0.154로 나소 낮게 나타났고, SEE는 6.36~6.37 ㎖/kg/min으로 유사하게 나타났고, CV도 15.7%로 유사하게 나타났다. 1,200 m 달리기 모형의 R은 0.444이고, SEE는 4.82 ㎖/kg/min, CV는 11.9%로 나타났다. 결론적으로 Bruce protocol을 이용하여 실시한 최대산소섭취량 추정 방법 중 실용적인 유용성과 간편성을 고려하면 대사반응을 이용한 6분모형과 3분모형이 적합한 모형으로 나타났고, 심박수 모형과 달리기 모형은 추정의 정확도가 다소 낮게 나타났다.

• 산업경영시스템학회지
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• 제44권4호
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• pp.65-75
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• 2021

This study explores multiple variables of an OTT service for discovering hidden relationship between rating and the other variables of each successful and failed content, respectively. In order to extract key variables that are strongly correlated to the rating across the contents, this work analyzes 170 Netflix original dramas and 419 movies. These contents are classified as success and failure by using the rating site IMDb, respectively. The correlation between the contents, which are classified via rating, and variables such as violence, lewdness and running time are analyzed to determine whether a certain variable appears or not in each successful and failure content. This study employs a regression analysis to discover correlations across the variables as a main analysis method. Since the correlation between independent variables should be low, check multicollinearity and select the variable. Cook's distance is used to detect and remove outliers. To improve the accuracy of the model, a variable selection based on AIC(Akaike Information Criterion) is performed. Finally, the basic assumptions of regression analysis are identified by residual diagnosis and Dubin Watson test. According to the whole analysis process, it is concluded that the more director awards exist and the less immatatable tend to be successful in movies. On the contrary, lower fear tend to be failure in movies. In case of dramas, there are close correlations between failure dramas and lower violence, higher fear, higher drugs.

• 한국작물학회지
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• 제50권4호
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• pp.247-255
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• 2005

ice yield and plant growth response to nitrogen (N) fertilizer may vary within a field, probably due to spatially variable soil conditions. An experiment designed for studying the response of rice yield to different rates of N in combination with variable soil conditions was carried out at a field where spatial variation in soil properties, plant growth, and yield across the field was documented from our previous studies for two years. The field with area of 6,600 m2 was divided into six strips running east-west so that variable soil conditions could be included in each strip. Each strip was subjected to different N application level (six levels from 0 to 165kg/ha), and schematically divided into 12 grids $(10m \times10m\;for\;each\;grid)$ for sampling and measurement of plant growth and rice grain yield. Most of plant growth parameters and rice yield showed high variations even at the same N fertilizer level due to the spatially variable soil condition. However, the maximum plant growth and yield response to N fertilizer rate that was analyzed using boundary line analysis followed the Mitcherlich equation (negative exponential function), approaching a maximum value with increasing N fertilizer rate. Assuming the obtainable maximum rice yield is constrained by a limiting soil property, the following model to predict rice grain yield was obtained: $Y=10765{1-0.4704^*EXP(-0.0117^*FN)}^*MIN(I-{clay},\;I_{om},\;I_{cec},\;I_{TN},\; I_{Si})$ where FN is N fertilizer rate (kg/ha), I is index for subscripted soil properties, and MIN is an operator for selecting the minimum value. The observed and predicted yield was well fitted to 1:1 line (Y=X) with determination coefficient of 0.564. As this result was obtained in a very limited condition and did not explain the yield variability so high, this result may not be applied to practical N management. However, this approach has potential for quantifying the grain yield response to N fertilizer rate under variable soil conditions and formulating the site-specific N prescription for the management of spatial yield variability in a field if sufficient data set is acquired for boundary line analysis.

• Journal of Mechanical Science and Technology
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• 제17권3호
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• pp.350-356
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• 2003

In this study, a numerical analysis for the piston secondary dynamics of small refrigeration reciprocating compressors is performed. In general, the length of cylinder in this class of compressors is shortened to diminish the frictional losses of the piston-cylinder system. So, the contacting length between piston and cylinder wall is in variable with the rotating crank angle around the BDC of the reciprocating piston. In the problem formulation of the piston dynamics, the variation in bearing length of the piston and all corresponding forces and moments are considered in order to determine the piston trajectory, velocity and acceleration at each step. A Newton-Raphson procedure was employed in solving the secondary dynamic equations of the piston. The developed computer program can be used to calculate the entire piston trajectory and the lubrication characteristics as functions of crank angle under compressor running conditions. The results explored the effects of some design parameters and operating conditions on the stability of the piston, the oil leakage, and friction tosses.

• Tribology and Lubricants
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• 제18권4호
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• pp.291-298
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• 2002

In this study, a numerical analysis f3r the piston secondary dynamics and lubrication characteristics of small refrigeration reciprocating compressors is presented. In general, the length of cylinder in this class of compressors is shortened to diminish the frictional losses of the piston-cylinder system. So, the contacting length between piston and cylinder wall is in variable with the rotating crank angle around the BDC of the reciprocating piston. In the problem formulation of the piston dynamics, the change in bearing length of the piston and all corresponding forces and moments are considered in order to determine the piston trajectory, velocity and acceleration at each step. A Newton-Raphson procedure was employed in solving the secondary dynamic equations of the piston. The developed computer program can be used to calculate the entire piston trajectory and the hydrodynamic forces and moments as functions of crank angle under compressor running conditions. The results explored the effects of the radial clearance, lubricant viscosity, and pin location on the stability of the piston, the oil leakage, and friction losses.