• Journal of Korean Society of Forest Science
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• v.110 no.2
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• pp.233-243
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• 2021

Considering worldwide efforts to mitigate repercussions of climate change, the South Korean government has declared to reach net zero by 2050 to achieve a carbon-neutral sustainable society. For full implementation of NDCs, the government has actively reflected its forestry sector into these strategies. Since coarse woody debris (CWD) in forests represents an enduring carbon storage, it is of particular significance to determine characteristics of changes in carbon stocks of CWD by utilizing data on dead trees monitored in permanent sample plots within national forest inventories (NFIs). In this study, therefore, both occurrence and carbon stocks of CWD were estimated in such plots using data on CWD from the 5^th, 6^th, and 7^th NFIs. Subsequently, characteristics of changes in carbon stocks over time were analyzed. Based on the analysis of 2,021 plots available for monitoring in each NFI of Gangwon Province, the volume of CWD (m³ ha^-1) was found to be 4.71 in the 5^th NFI and 4.09 in the 6^th NFI. However, the volume of CWD declined to 3.09 in the 7^th NFI. Moreover, the annual carbon stocks of CWD (ton C ha^-1) were estimated to be 0.67 in 2009, 0.64 in 2014, and 0.41 in 2019, showing a downward trend over time. This study provides a basis for future research to investigate long-term changes and estimate carbon stocks of CWD in South Korea forests.

• Proceedings of the Safety Management and Science Conference
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• 2006.04a
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• pp.421-428
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• 2006

It is an hot issue to reduce vibration for improving quality, reliability and safety in railway vehicles including magnetic levitation, monorail way, surface car etc. This paper aims at literature survey in rolling stocks vibration standards. Firstly, we investigate literature concerned vibration test standards and compare these standards. Secondly, we give some suggestions for future study and developing new test standards.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2003.05a
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• pp.5-17
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• 2003

This paper examines the effects of IT technology capital and R&D stock's variation on the growth of Korea's industries with the empirical approaches. We analyze the Granger causality and Impulse response function analysis among the Korea's industrial real output, IT technology capital, and R&D stocks. When it comes to this research conclusion, we know that IT technology capital and R&D stock's shocks affect the growth of Korea's industrial sector in terms of increasing in the real output growth rate.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.32
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• pp.113-120
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• 1994

This study presents a two level-parallel type inventory systems with one upper level facility in the first echelon and n-lower level facilities in the second echelon. The stocks at the lowest facilities can become unbalanced with the random variations in the demands. This paper deals with the imbalance by considering redistribution and backorder. The system with redistribution and the system with backorder and redistribution are analized. The comparison of two cases shows that the system with redistribution and backorder gives smaller stocks than the system with redistribution.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.481-484
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• 2008

The important factor to evaluate the running safety of a railway vehicle would be the interaction force between wheel and rail(derailment coefficient), for which is one of important factors to check the running safety of a railway vehicle that may cause a tragic accident. Element that analyze derailment coefficient is consisted of wheel load and lateral force. In this paper, studied about method that calculate vertical force(wheel load) by bending load of axle in rolling stocks.

• The Korean Journal of Applied Statistics
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• v.25 no.4
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• pp.543-552
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• 2012

Parrondo paradox is a counter-intuitive phenomenon where two losing games can be combined to win or two winning games can be combined to lose. When we trade stocks with a history-dependent Parrondo game rule (where we buy and sell stocks based on recent investment outcomes) we found Parrondo paradox in stock trading. Using stock data of the KRX from 2008 to 2010, we analyzed the Parrondo paradoxical cases in the Korean stock market.

• Journal of the Korean Society for Railway
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• v.5 no.3
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• pp.181-186
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• 2002

Aluminum rolling stocks have been developed for six years in Korea and commercial trainsets are being constructed by the carbuilder. Aluminum alloys are sensitive to various imperfections. In this paper, damages and failures of the aluminum carbody taking place during the process of development are investigated and accumulated data are released. Also, remedies for the failures are suggested and design changes are introduced. It is expected that all informations can contribute to construction of reliable and safe aluminum rolling stocks.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.616-621
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• 2003

MIG or TIG welding has been the most popular welding process for joining aluminum alloy structures. However, porosity, hot crack and distortion were serious problems in inert gas fusion welding. Since FSW(Friction Stir Welding) was invented by TWI in 1991, it has been the powerful candidate for solving the problems of inert gas welding. In this paper, the principle and characteristics of FSW is introduced and its application to rolling stocks is presented to make basis for future development in production technology of aluminum rolling Stocks.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.226-233
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• 2000

This study has been performed to develop the practical method to estimate the change of dynamic characteristics of rolling stocks passing on the high speed turnout system. Each part of turnout system are modeled in consideration of alignment, enter angle and amount of deflection and they are used to achieve dynamic analysis with a train model. Analysis results are compared with test results to confirm its validation

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.467-468
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• 2007

This paper describes characteristics of converters of auxiliary power supply for electric railway vehicles. Auxiliary power supply is called Static Inverter(SIV) which supplied lamps, air conditioning and heat equipments, control systems, etc. Simulation results shows that line No.1 cheon contains low harmonics compared with those of KTX.