• International Area Studies Review
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• v.13 no.3
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• pp.385-412
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• 2009

This study first analyzes economical environment change (factor) of investment nation Japan and Japanese enterprise at the analysis of Japanese enterprise's over-seas expansion factor and influence. As a result of an analysis of the factor about Japanese enterprise's overseas expansion from 1990 to 1996 and from 1998 to 2006, commonly applied factors were Yen exchange rate, interest rates, wage, enterprise profit, facility investment, and consumption expenditure. Especially, as a result of regression analysis, a sudden change of "low interest rate" was main factor at Japanese enterprise's overseas expansion from 1990 to 1996, and Japan's "Yen ex-change rate" was drawn as an important factor from 1998 to 2006. That is, from 1990 to 1996, a shock by a sudden rise in Yen value could be viewed gradually accumulated and absorbed inside Japanese economy from 1998 to 2006. Whereas it could be said that Japanese enterprise's overseas expansion was accelerated under Japanese government's overseas supporting policy and "low interest rate" together with the factor in the rise of Yen value from 1998 to 2006.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.85.1-85.1
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• 2011

In this study, Grafoil$^{TM}$ which has comparable electric resistance and chemical stability but is flexible, fragile, and cheap material was adopted as bipolar plates for proton exchange membrane fuel cell(PEMFC) having only one straight line flow channel. Because of its flexibility, pressurizations of cell with various pressures showed different operating characteristics compared to ordinary graphite-used PEMFC. While performances of both cells decreased as these were pressurized, investigation of ohmic and faradaic resistance by electrochemical impedance measurement indicated different tendency of change. Ohmic resistance of graphite-used cell increased with increasing pressure, which is reversed in Grafoil$^{TM}$-used cell. It is speculated that effective chemical reaction area is decreased with increasing pressure in case of graphite-used one, but because of flexible property of Grafoil$^{TM}$, gas diffusion layer in Grafoil$^{TM}$-used cell was well-activated. Different rate of change of faradaic resistances in both cells support this supposition. However, although optimum point of pressurization is found, it is required to investigate other operating conditions because of low performance compared to graphite-used cell.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.4
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• pp.857-861
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• 2021

The study aims to find the asymmetric effect in National Stock Exchange in which the Nifty50 is considered as proxy for NSE. A return can be stated as the change in value of a security over a certain time period. Volatility is the rate of change in security value. It is an arithmetical assessment of the dispersion of yields of security prices. Stock prices are extremely unpredictable and make the investment in equities risky. Predicting volatility and modeling are the most profuse areas to explore. The current study describes the association between two variables, namely, stock yields and volatility in equity market in India. The volatility is measured by employing asymmetric GARCH technique, i.e., the EGARCH (1,1) tool, which was used in building the study. The closing prices of Nifty on day-to-day basis were used for analysis from the period 2011 to 2020 with 2,478 observations in the study. The model arrests the lopsided volatility during the mentioned period. The outcome of asymmetric GARCH model revealed the subsistence of leverage effect in the index and confirms the impact of conditional variance as well. Furthermore, the EGARCH technique was evidenced to be apt in seizure of unsymmetrical volatility.

• Proceedings of KOSOMES biannual meeting
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• 2009.06a
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• pp.89-94
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• 2009

This study aims to examine the the characteristics if the sea water circulation in related to the change of the water exchange rate according to the the development phases of Busan Port. To clarify the characteristics, the water exchange caused by construction if new-port and river discharge conditions was examined by the numerical experiments using the Lagrangian particle tracking model based on 2-D shallow water equation. This study deals with the charge of flow field and water exchange after redevelopment using numerical simulation technique, based on the field observation and 4 rivers discharge flow. As a result if numerical simulation, Variation if current velocity in Busan North Port is almost nothing before and after construction. Water exchange of channel in area of redevelopment is a little. Futhermore, the tidal exchange had a tendency to be small both before and after redevelopment by 60%.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.179_180
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• 2009

계통에 외란이 발생하면 전압 붕괴 현상으로 이어져 제어될 수 없는 부하손실이나 캐스케이딩 현상의 형태로 발전 될 수 있다. 심각한 경우에 광역정전으로 확대되는 문제점이 생기는데, 이를 방지하기 위한 방안으로 최소한의 부하차단을 통하여 계통을 안정화시켜야 하며 불필요한 부하차단을 방지하기 위한 부하차단 다단계화가 수행 되어야 한다. 본 논문에서는 모선 전압의 민감도에 따른 적정한 부하차단 개소를 선택하였으며 부하차단 의사결정 방안으로 전압 변동률을 고려하여 다단계 부하차단 방안을 검토하였다. 전압변동율의 계산을 위하여 Least square 기법이 적용되었으며 2008년도 하계 최대부하 계통에 대한 동적 해석을 수행하였고, 계통 해석 결과를 바탕으로 이전에 제안 된 방안들에 비하여 향상되고 발전된 효율적인 저전압 부하차단 방안에 대하여 논의하였다.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1103-1112
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• 2013

Exploratory data analysis focuses mostly on data exploration instead of model fitting. We can use the recurrence plot as a graphical exploratory data analysis tool. With the recurrence plot, we can obtain the structural pattern of the time series and recognize the structural change points in time series at a glance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.4
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• pp.576-582
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• 1996

This work studies qualitative thermal characteristics of PCM cold storage medium container and its surrounding streams. Experimental parameters are initial PCM temperature and cold water flow rate. A mathematical modeling was establised to estimate temperature distribution and the cooling process. We found that the phase-change temperatures of PCM varies from 6 to $8^{\circ}C$ which is constant for other materials and that the dominant heat transfer resistance is that on the container side taking about 3/4 of the total resistance. The one dimensional mathematical model predicts experimental data quit well.

• Journal of Power System Engineering
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• v.17 no.6
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• pp.130-135
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• 2013

It is a research about the change in reduction efficiency and performance resulting from installation of the EGR cooler, which is the core technology reducing NOx in response to standards been tightened of exhaust controls for off-road vehicle. It can reduce NOx by altering combustion temperature and oxygen concentration by recycling high-temperature exhaust gas. The target engine was large diesel engine for construction machine through by which we were able to verify a rate of change in output and capabilities for a heat-exchange within cooler itself depending on the existence of EGR cooler system. We have acquired a emission reduction technology for a construction machine by testing the reduction performance and rate of change in output.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.1 s.139
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• pp.10-17
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• 2005

Due to emission of vehicles during loading/unloading, ventilation system in Roll-on/Roll-off ship is inevitable; however it is very difficult to predict the ventilation performance before it is finally built in. Although the requirements for the ventilation system include air change rate and maximum allowable concentration of CO in the cargo holds, even prototype tests are hardly able to quantify the ventilation performance. In the present paper, a new method to assess the ventilation performance of Roll-on/Roll-off ship is proposed by using computational fluid dynamics. The air exchange is modeled by introducing multi-species transport of existing air In the holds and new air from the ventilation system. Conservation of multi-species as well as 3D Navier-Stokes equation are solved numerically in time dependent manner. Several cases of different configuration are considered. The results include predicted mass fraction of new air in the holds. It is also presented that CO concentration can be estimated based on the predicted air change performance. Due to the lack of experimental data, the computed results are not verified; however the proposed method can be applied as au assessment tool.

• Journal of Biosystems Engineering
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• v.36 no.5
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• pp.334-341
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• 2011

This study was conducted to compare the characteristics of heat dissipated from LED lamps with water cooling method and natural cooling method in a closed-type plant production system (CPPS) and to determine the optimum water temperature and flow rate for LED lamps with water cooling method. The experiments were performed in CPPS maintained at temperature of $24^{\circ}C$ and humidity of 70%. As compared to the LED lamps operated at water temperature of $22.5{\pm}1.2^{\circ}C$ and flow rate of $1,521{\pm}3.3\;mL{\cdot}min^{-1}$, air temperature under LED lamps with natural cooling was approximately increased by $1^{\circ}C$ and photosynthetic photon flux was decreased by $10{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. PPF illuminated from LED lamps was affected by forward voltage varied by the surface temperature of LED lamps. Forward voltage of LED lamps was decreased with increasing surface temperature and then PPF was proportionately decreased. Five levels ($14^{\circ}C,\;17^{\circ}C,\;20^{\circ}C,\;23^{\circ}C,\;26^{\circ}C$) of water temperature and three levels ($500\;mL{\cdot}min^{-1}$, $1,000\;mL{\cdot}min^{-1}$, $1,500\;mL{\cdot}min^{-1}$) of flow rate were provided to analyze the change of surface temperature and heat exchange of LED lamps. Heat exchange was increased with decreasing water temperature and increasing flow rate. At flow rate of $1,000-1,500\;mL{\cdot}min^{-1}$ and water temperature of 22.0-$22.6^{\circ}C$, surface temperature of LED lamps can be approached to $24^{\circ}C$ that was almost same as air temperature in CPPS. The calorific value generated from LED lamps used in the study was estimated to be $103.0\;kJ{\cdot}h^{-1}$.