• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.3-6
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• 2003

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.452-455
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• 2007

The geothermal heat pump system is designed for cooling and heating for three stories building (2,435 $m^2$) includes total 79 heat pumps. Therefore, the monitoring system is installed for each floor and the data is automatically transmitted to the monitoring system. Heat exchange rate and temperature of a geothermal heat pump system have been monitored for a long period. The seasonal operation of geothermal heat pump shows the different shape of heat exchange rate for cooling and heating. Ground water flow can influence on heat exchange rate and thermal storage of the system. In order to define the hydraulic characteristics and groundwater temperature variation, the relationships among air temperatures, groundwater temperatures, water table, and precipitation are analysed.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.1
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• pp.51-56
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• 2008

The counter-fire operation system performs its mission exchanging information with other related systems such as command & control systems and military information systems. In the process of exchanging information, the counter-fire operation system uses a type of data message which contains exchange data information in the format of KMTF. The requirement of data exchange of count-fire operation will continue to evolve. But the EDX(External Data eXchange) configuration item of the current counter-fire operation system can not effectively cope with the variation of data exchange requirements due to its fixed software structure. In the paper, a solution for improving flexibility of external data exchange in counter-fire operation system is proposed.

• KIEE International Transactions on Power Engineering
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• v.5A no.3
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• pp.221-227
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• 2005

This paper evaluates minimum and maximum power exchange considering economic and technical characteristics between Russia and ROK. First, we evaluate minimum power exchange to assure the economic feasibility by comparison with the total cost and benefit of the interconnected line. For evaluating maximum exchange power, system constraints are considered, which are examined through load flow and dynamic analysis by using the PSS/E program. As a result of these evaluations, we suggest the reasonable range of power exchange between ROK and Russia considering economic and technical constraints with the interconnection scenario that power system interconnection between ROK and Russia will be realized in the year 2010.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.5
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• pp.35-46
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• 2006

The current Internet Key Exchange protocol(IKE) which has been used for key exchange of security system was pointed out the faults of scalability, speed, efficiency and stability. In this research, we tried to resolve those faults, and implemented the newly designed IKEv2 protocol in the IPsec test bed system. In the trend of network expansion, the current Internet Key Exchange protocol has a limitation of network scalability, so we implemented the new Internet Key Exchange protocol as a recommendation of RFC proposal, so as to resolve the fault of the key exchange complexity and the speed of authentication process. We improved the key exchange speed as a result of simplification of complex key exchange phase, and increased efficiency with using the preexistence state value in negotiation phase.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.125-130
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• 2020

At the end of 1997, the volatility of the exchange rate intensified as the nation's exchange rate system was converted into a free-floating exchange rate system. As a result, managing the exchange rate is becoming a very important task, and the need for forecasting the exchange rate is growing. The exchange rate prediction model using the existing exchange rate prediction method, statistical technique, cannot find a nonlinear pattern of the time series variable, and it is difficult to analyze the time series with the variability cluster phenomenon. And as the number of variables to be analyzed increases, the number of parameters to be estimated increases, and it is not easy to interpret the meaning of the estimated coefficients. Accordingly, the exchange rate prediction model using artificial neural network, rather than statistical technique, is presented. Using DNN, which is the basis of deep learning among artificial neural networks, and LSTM, a recurrent neural network model, the number of hidden layers, neurons, and activation function changes of each model found the optimal exchange rate prediction model. The study found that although there were model differences, LSTM models performed better than DNN models and performed best when the activation function was Tanh.

• Journal of Environmental Science International
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• v.16 no.8
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• pp.907-912
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• 2007

Ion exchange resin was used to remove silica ion at ultralow concentration. The effects of temperature, type of ion exchange resin and single/mixed-resin systems on removal efficiency were estimated. As temperature increased, the slope of concentration profile became stiff, and the equilibrium concentration was higher. In the single resin system, the removal of silica was continued up to 400 min, but the silica concentration was recovered to initial concentration after 400 min due to the effect of dissolved $CO_2$. In the mixed-resin system it took about 600 min to reach equilibrium. Because of faster cation exchange reaction than anion exchange reaction, the effect of $CO_2$ could be removed. Based on the experimental results carried out in the mixed-resin system, the selectivity coefficients of silica ion for each ion exchange resin were calculated at some specific temperatures. The temperature dependency of the selectivity coefficient was expressed by the equation of Kraus-Raridon type.

• Proceedings of the KIEE Conference
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• summer
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• pp.107-109
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• 2004

It is very important to operate a power system safely. An fault may causes the cascading outages in power system. Use of systematic, precise definitions related to the outages is essential for meaningful exchange of data. Moreover, it is necessary that specific instructions for reporting outages is developed. This paper presents the outage management for a power system. The outage managements of the many utilities are researched, which include the definition, classification, index and report of outage. Finally, the outage management standard is proposed, and the necessity and structure of KERC(Korean Electric Reliability Council) are presented

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.2
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• pp.103-111
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• 2011

The reduction of setup time is very important in a lot production system. A punch press is a typical system of lot production. This paper describes a case study to reduce setup time of a punch press manufacturing system. Especially, this case study reduced the time of die exchange in the case that the standardization of die height is impossible realistically because of diversity on die height and heavy expenses. This study adopts a supplementary die and supplementary blocks to make the use of auto-clamping device possible. The paper also gives a sequencing algorithm to reduce the number of exchange of the supplementary die.

• ETRI Journal
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• v.19 no.3
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• pp.169-185
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• 1997

This paper presents the design concepts and the system architecture of a mobile exchange for CDMA Mobile System. The paper also discusses complex subsystems in this system and design concepts of these subsystems. To evaluate the performance of the CDMA Mobile System, we have performed a computer simulation based on the framework of the mobile exchange. Simulation results are presented in terms of network traffic load (call attempts per second) and database performance requirements (transactions per second.)