• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.312-319
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• 2012

The life of a power transformer is dependent on the life of the cellulose paper, which influenced by the hot spot temperature. Thus, the determination of the cellulose paper's life requires identifying the hot spot temperature of the transformer. Currently, however, the power transformer uses a heat run test is used in the factory test to measure top liquid temperature rise and average winding temperature rise, which is specified in its specification. The hot spot temperature is calculated by the winding resistance detected during the heat run test. This paper measures the hot spot temperature in the single-phase, 154kV, 15/20MVA power transformer by the optical fiber sensors and compares the value with the hot spot temperature calculated by the conventional heat run test in the factory test. To measure the hot spot temperature, ten optical fiber sensors were installed on both the high and low voltage winding; and the temperature distribution during the heat run test, three thermocouples were installed. The hot spot temperature shown in the heat run test was $92.6^{\circ}C$ on the low voltage winding. However, the hot spot temperature as measured by the optical fiber sensor appeared between turn 2 and turn 3 on the upper side of the low voltage winding, recording $105.9^{\circ}C$. The hot spot temperature of the low voltage winding as measured by the optical fiber sensor was $13.3^{\circ}C$ higher than the hot spot temperature calculated by the heat run test. Therefore, the hot spot factor (H) in IEC 60076-2 appeared to be 2.0.

• The Journal of Asian Finance, Economics and Business
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• 제5권3호
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• pp.7-17
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• 2018

This paper examines short-run and long-run dynamic relationships between selected macroeconomic variables and stock prices in the Korea Stock Exchange. The data is restricted to the period for which monthly data are available from January 1986 to October 2016 (370 observations) retrieved from the Economic Statistics System database sponsored by the Bank of Korea. The study employs unit root test, cointegration test, vector error correction estimates, impulse response test, and structural break test. The results of the Johansen cointegration test indicate at least three cointegrating equations exist at the 0.05 level in the model, confirming that there is a long-run equilibrium relationship between stock prices and macroeconomic variables in Korea. The results of vector error correction model (VECM) estimates indicate that money supply and short-term interest rate are not related to stock prices in the short-run. However, exchange rate is positively related to stock prices while the industrial production index and inflation are negatively related to stock prices in the short-run. Furthermore, the VECM estimates indicate that the external shock, such as regional and global financial crisis shocks, neither affects changes in the endogenous variables nor causes instability in the cointegrating vector. This study finds that the endogenous variables are determined by their own dynamics in the model.

• 전기학회논문지P
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• 제66권3호
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• pp.110-116
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• 2017

System to automate the trial-run of energy storage system for frequency regulation was developed and demonstrated. Basic strategy was developed on the basis of trial-run procedure and verified in the computer simulation tool. The algorithm was developed and coded for 4MW trial-run automation system. 4MW trial-run automation system was connected to 4MW energy storage system for frequency regulation in Jocheon substation of Jeju city and demonstrated. 24MW trial-run automation system was developed on the basis of 4MW trial-run automation system and verified by operation system for 24MW energy storage system for frequency regulation. The operation system has own simulation model of energy storage system and power system. The verification was performed to improve the system in the view of user. 24MW trial-run automation system was demonstrated in 32MW Ul-san and 36MW Non-gong energy storage system. All tests of trial-run was done by manual and first they ware taken 1 week with no trial-run automation system. The manual trial-run tests were taken by maximum three times. Trial-run test by trial-run automation system was taken 2 days. The system helps reduce the trial-run test period and improve the accuracy of tests.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.991-992
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• 2012

• The Journal of Asian Finance, Economics and Business
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• 제7권12호
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• pp.677-682
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• 2020

To investigate the nexus between urban population, gross capital formation, and economic growth in the Kingdom of Saudi Arabia, yearly data was collected from the World Bank for the period 1974- 2018. Basic statistics test and correlation matrix was used to investigate the causal effect among the tested parameters, followed by Augmented Dickey-Fuller (ADF) stationary test, co-integration analysis by Johansen test after that Vector Auto-Correction Model for both short-run and long-run and finally the Granger-Causality tests. Result of unit root test analysis shows that the urban population became stationary at I (0) level while economic growth and gross capital formation became stationary at I (1). Johansen co-integration analysis indicates that there is presence of both long-run and short-run relationship between the three variables in the Kingdom of Saudi Arabia. The result of the VECM Model reflects that both economic growth and gross capital formation have a negative impact on urban population in the short run. According to the Granger-Causality tests, there is unidirectional causality with the urban population by both gross capital formation and economic growth. Also, the result of the Granger Causality tests show that there is unidirectional causality between economic growth and gross capital formations.

• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.37-41
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• 2021

This study aims to investigate the relationship between the exchange rate and Trade Balance. Trade Balance is used as the dependent variable, and the independent variables are Exchange Rate, Gross Domestic Product, and Inflation. Augmented Dickey-Fuller unit root test was adopted to test the stationary property of time series data, Auto Regressive Distributed Lag model was employed to find the long run and short-run relationship and long-run adjustment, Bound test approach, the unrestricted Error Correction Model and Granger Causality Test are used to analyze the data from 1977 to 2019. The research findings suggest that inflation has a positive impact on the trade balance in the short run. The exchange rate and the Gross Domestic Product have adverse effects on Trade balance in the long run. The coefficient of ER in the previous year is negative, and the coefficient of TB in the previous year is positive and significant. This is consistent with the J-Curve phenomenon, which states that devaluation may not improve trade balance in the immediate period, but will significantly impact the trade balance improvement in subsequent periods. Hence Marshall Lerner Condition exists in Sri Lanka.

• 운동과학
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• 제21권2호
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• pp.183-190
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• 2012

본 연구의 목적은 엘리트 선수들의 에너지 기여비율에 기인된 종목특성에 따른 20 m 셔틀런 검사를 이용한 심페지구력 측정의 유용성을 평가하는데 있다. 본 연구에 참여자는 K 국립체육대학교에 재학중인 학생 67명을 대상으로 하였으며, 종목 특성은 무산소성종목(단거리, 도약, 역도, 투척; 35명), 유산소성 종목(중장거리; 9명), 투기종목(유도; 23명)으로 3집단을 구성하였다. 20 m 셔틀런 검사는 Leger et al.(1982)방법을 이용하였으며, 측정된 셔틀런 횟수를 이용한 가속도 산출은 Brewer et al.(1988) 방법을 이용하였다. 유용성 평가를 위한 VO₂max 준거검사는 트레이드밀을 이용한 점증부하 방법을 실시하였으며, 순발력 체력요인은 제자리멀리뛰기와 50 m 달리기를 이용하였다. 순발력, 민첩성, 근지구력을 고려한 체력요인은 Z-점프를 측정하였다. 종목별 체력특성차이는 제자리멀리뛰기와 50 m 달리기에서 무산소성 집단(Anaerobic Group; AnG)이 유산소성집단(Aerobic Group; AeG)과 투기종목집단(Combat Sport Group; CG)에 비해 유의하게 높았다(p<.05). 하지만 Z-점프는 CG가 AnG와 AeG에 비해 유의하게 높았다(p<.05). 20 m 셔틀런 검사결과와 VO₂max관련성은 AnG(r= 0.577, p<.0001)와 CG(r= 0.760, p<.0001)에서 유의하게 높은 상관계수를 나타내었으나 AeG는 낮은 상관계수를 나타내었다. 20-셔틀런검사의 유용성평가를 위한 집단간 차이는 20 m 셔틀런 검사결과를 VO₂max로 전환하였을 때 집단 간 차이가 없었으며 오차가 감소하는 것을 발견하였다. 우리는 이번 연구에서 20 m 셔틀런 검사의 유용성을 판단하였으며 셔틀런 검사횟수를 이용한 VO₂max 산출에 따른 오차가 감소하는 것으로 나타나 현장 활용적인 측면에서 셔틀런 검사를 종목 구분 없이 보편적으로 이용하기 위해 VO₂max전환의 필요성을 확인할 수 있었다.

• 대한전자공학회논문지SD
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• 제41권9호
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• pp.85-95
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• 2004

최근 반도체 칩의 집적도가 올라가고 System-on-Chip(Soc)환경이 보편화되면서 Automatic Test Equipment(ATE)를 이용한 테스트 수행시 테스트 패턴의 크기 문제와 스캔체인에서의 전력 소모문제가 크게 부각되고 있다. 또한, 테스트 패턴 크기문제를 해결하기 위해 테스트 패턴을 압축하게 되면 테스트 패턴의 소모하는 전력량이 커지게 되어 저전력 테스트를 수행하는데 어려움이 있어 두 가지 문제를 해결할 수 없었다 본 논문에서는 이러한 문제점들을 동시에 해결하기 위해서 Run-length code를 기반으로 하여 저전력 테스트가 가능하면서 테스트 패턴의 크기도 줄일 수 있는 알고리즘을 제안하였다. 본 논문에서는 기존에 제시되었던 알고리즘과 비교ㆍ분석하는 실험을 통하여 이 알고리즘의 효율성을 보여주고 있다.

• 수산경영론집
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• 제40권2호
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• pp.105-126
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• 2009

This study applies the cointegration theory to analyse the causality of the prices between imported fisheries and domestic fisheries in distribution channel. We've focused on the prices of import, wholesale and retail about the frozen Alaska pollack, hairtail and croaker which take up high portion and are popular among most of the consumers. In process of analysis, the unit root test was adopted to find the stability of time series data prior to the cointegration test. If the time series data was found as stable one in unit root test, we should analyse the VAR model. If unstable, the cointegratioin test was adopeted to find the long-run equilibrium relationship between the data. When the long-run equilibrium relationship was found among the price of the import, wholesale and retail price, the VECM model was adoped. If not, the differenced VAR model was adopted. The main findings of this study could be summarized as follows ; First, according to the result of the analysis on VAR model, time series data of frozen Alaska pollack was found as stable and has causality relationship and close effect was existing among the import, wholesale and retail price. Second, the data of frozen hairtail was found as an unstable one in unit root test and the result of cointegration test showed the long-run equilibrium relationship at lag 1. From the results of VECM model, we could find that the coefficient of error correction is effective, and the sign is negative(-). It means that the existence of adjustment tendency to long-run equilibrium after a short-run deviation. But the short-run causality of the prices were not found except the price of wholesale. Third, according to the results of differenced VAR model, data from frozen croaker did not have the stability and long-run equilibrium. Moreover, it was found that the import price has a weak causality on the retail price. Because of having difficulties in collecting data, the result of this paper could not explain the relationship among the prices of import, wholesale and retail perfectly. However, it more or less contributed to a long-lasted debate on the direction of causality of price-setting in academic research and provided a useful guide for the policy makers in charge of the price-setting of fisheries products as well.

• The Journal of Asian Finance, Economics and Business
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• 제8권1호
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• pp.81-91
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• 2021

This paper investigates the long run hedging ability of precious metals against the risks associated with adverse conditions of economic and financial variables for Pakistan, the USA, China, and India. Monthly data of gold, silver, platinum, stock returns, exchange rate, industrial production, and inflation was collected for the selected economies. Saikkonen and Lutkepohl (2002) unit root test was employed to access the unit root properties of the data series and identify the break dates. Furthermore, this study used the Johansen cointegration test with and without structural breaks to identify the long-run relationship between metals prices and different financial and economic variables. The findings suggest that the time series under study have unit root problem at level with and without structural breaks. Without considering structural breaks, the Johansen trace test indicates that in Pakistan and China, gold, silver, and platinum hold a cointegrating relationship with macroeconomic and financial variables. For the US, gold indicates cointegration which supports the hedging ability of gold against inflation, stock, and industrial production in the long run. The results of the cointegration test after incorporating the structural breaks provide even stronger evidence of the long-run relationship of precious metals and consumer prices, exchange rate, and stock prices.