• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.10 no.2
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• pp.41-47
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• 2006

The Renewal process and the Non-homogeneous Poisson process (NHPP) process are probably the most popular models for describing the failure pattern of repairable systems. But both these models are based on too restrictive assumptions on the effect of the repair action. For these reasons, several authors have recently proposed point process models which incorporate both renewal type behavior and time trend. One of these models is the Modulated Power Law Process (MPLP). The Modulated Power Law Process is a suitable model for describing the failure pattern of repairable systems when both renewal-type behavior and time trend are present. In this paper we propose Bayes estimation of the next failure time after the system has experienced some failures, that is, Mean Time Between Failure for the MPLP model. Numerical examples illustrate the estimation procedure.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.142-144
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• 2008

The Former High Efficiency Inverter(the power restoration process) system process has advantage which is the energy reduction rather than the Former Inverter(the resistence damping process), However, under repair and remodeling, the power facilities capacity is not easy to increase that the former High Efficiency Inverter needs to increase the Power Facilities Capacity of 20~30% than the Inverter(the resistence damping process) so Therefore we are going to suggest the system which is not going to make an increase the power facilities capacity and is applicable the High Efficiency Inverter.

• Proceedings of the Technology Innovation Conference
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• 1999.06a
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• pp.176-202
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• 1999

Korea has exerted her efforts to assimilate nuclear power technology, and reportedly localized 95 percent of nuclear power technology by 1995. This paper investigates the evolution of nuclear power program in Korea to exploit the development process of the nuclear power industry and key factors for the technological localization of nuclear power plant. In developing countries, an imitative catching-up process can be shown as a course for developing the absorptive capacity of foreign technology, which depends on prior knowledge base and the intensity of effort. The process of technological learning consists of five stages including preparation, implementation of foreign technology, acquisition of peripheral technology, acquisition of core technology, and improvement f foreign technology. Moreover, this paper discusses six essential factors that have influenced the successful achievement of technological localization of nuclear power plants in Korea. They include the role and strategies of the government, the leading role of utility firm, the development and cooperation of the related organizations, the development of human resources and their efforts, market conditions and the assistance of foreign donors, and social conditions. Finally, this paper discusses about implications offered by the Korean experience for other developing countries.

• Journal of the Korean Statistical Society
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• v.34 no.4
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• pp.331-344
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• 2005

Inference on current data could be more reliable if there exist similar data based on previous studies. Ibrahim and Chen (2000) utilize these data to characterize the power prior. The power prior is constructed by raising the likelihood function of the historical data to the power $a_o$, where $0\;{\le}\;a_o\;{\le}\;1$. The power prior is a useful informative prior in Bayesian inference. However, for model selection or model comparison problems, the propriety of the power prior is one of the critical issues. In this paper, we suggest two joint power priors for the power law process and show that they are proper under some conditions. We demonstrate our results with a real dataset and some simulated datasets.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.5
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• pp.563-569
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• 2015

For some low-frequency applications such as power-related circuits, NEM relays have been known to show better performance than MOSFETs. For example, in a step-down charge pump circuit, the NEM relays showed much smaller layout area and better energy efficiency than MOSFETs. However, severe process variations of NEM relays hinder them from being widely used in various low-frequency applications. To mitigate the process-variation problems of NEM relays, in this paper, a new NEM-relay charge pump circuit with the self-adjustment is proposed. By self-adjusting a pulse amplitude voltage according to process variations, the power consumption can be saved by 4.6%, compared to the conventional scheme without the self-adjustment. This power saving can also be helpful in improving the power efficiency of the proposed scheme. From the circuit simulation of NEM-relay charge pump circuit, the efficiency of the proposed scheme is improved better by 4.1% than the conventional.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.1
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• pp.33-38
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• 2018

This study applied upgrades to the processes of a 10 MW wet amine $CO_2$ capture pilot plant and conducted performance evaluation. The 10 MW $CO_2$ Capture Pilot Plant is a facility that applies 1/50 of the combustion flue gas produced from a 500 MW coal-fired power plant, and is capable of capturing up to 200 tons of $CO_2$. This study aimed to quantitatively measure efficiency improvements of post-combustion $CO_2$ capture facilities resulting from process upgrades to propose reliable data for the first time in Korea. The key components of the process upgrades involve absorber intercooling, lean/rich amine exchanger efficiency improvements, reboiler steam TVR (Thermal Vapor Recompression), and lean amine MVR (Mechanical Vapor Recompression). The components were sequentially applied to test the energy reduction effect of each component. In addition, the performance evaluation was conducted with the absorber $CO_2$ removal efficiency maintained at the performance evaluation standard value proposed by the IEA-GHG ($CO_2$ removal rate: 90%). The absorbent used in the study was the highly efficient KoSol-5 that was developed by KEPCO (Korea Electric Power Corporation). From the performance evaluation results, it was found that the steam consumption (regeneration energy) for the regeneration of the absorbent decreased by $0.38GJ/tonCO_2$ after applying the process upgrades: from $2.93GJ/ton\;CO_2$ to $2.55GJ/tonCO_2$. This study confirmed the excellent performance of the post-combustion wet $CO_2$ capture process developed by KEPCO Research Institute (KEPRI) within KEPCO, and the process upgrades validated in this study are expected to substantially reduce $CO_2$ capture costs when applied in demonstration $CO_2$ capture plants.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.1-6
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• 2014

PID(Proportional, Integral, Derivative) controller is one of the most used process controllers in nuclear power plants. The optimized parameter setting of process controller contributes to the stable operation and efficiency in the operating nuclear power plants. PID parameter setting is tuned when new process control system is established or process control system is changed. It is a burdensome work for I&C(Instrument and Control) engineers to tune the PID controller because it requires a lot of experience and knowledge. When the plant is in operation, inadequate PID parameter setting can be the cause of the unstable process of the plant. Therefore the results of PID parameter setting should be compared, simulated, verified and finally optimized. The practical PID tuning methods used in process controller are tuning operation calculation(Ziegler-Nicholes, Minimum TIAE, Lambda, IMC), exclusive tuning program based on computer and Matlab application. This paper introduces the various tuning methods and suggests an optimized PID tuning process in the operating nuclear power plants.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1350-1354
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• 2007

As the importance of low power design is emphasized, power consumption became one of the standards that represent the performance of the system. The purpose of this study is to decide design variable that minimize power consumption for the oxygen concentrator in two bed-one compressor 8 step PSA process that has above 90% purity at 3lpm by using given constants and selected parameters. Setting selected parameters as cycle time and equalization time, optimization for PSA process in the oxygen concentrator is progressed. For this, we need to know the features and basic principals of PSA process and to deduce objective function of performance analysis. Validations for objective function and lots of experiments are needed too. By using the characteristic curve of the compressor and the pressure curve of the process for 1 cycle, objective function was set. After theoretical 2 dimensional optimized paths was obtained. And then, by experiment, theoretical optimized path was verified.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.437-443
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• 2006

The Water usage is relationship which is close with the administrative cost from industrial facility. It is not easy to reduce a water usage. This research is the optimization of the waste water quantity which process waste water integration of the standard thermal power plant in system operate time. The turbine rotates by force of the steam and it produces an electricity. Demineralization Water is manufacture purity manufacturing equipment and it is supplied in power plant channel. We knew a possibility of reducing from pure control process. When it is reduced the Back Washing time, Rinsing time of the gravity filter and the activated carbon filter. Also, It is possible even from regeneration phase in Condensate Polishing Demineralization System. In addition, There is also the water which the drain of the sampling water for watching the condition of power plant process will be able to use. Integrates these processes it will be able to reduce an annual 30,000 ton degree. The research is want to use the fundamental data for the water curtailment of the power plant.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.5
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• pp.7-21
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• 2008

Based on the perspective of power fundamentals and power process, this study empirically investigated the manufacturing strategy which provided competitive advantages for the manufacturing companies in Korea. To do so, this study conducted the survey to chief production officers in Incheon, Kyoungki, and other provinces, and the data was processed by using the SPSS statistical package. According to the study results, the concordance process had positive impacts on the power process and the power process had positive impacts on the organizational performance. This result can provide many implications for the manufacturing companies in Korea.