• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.227-232
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• 2016

To test the effectiveness of using an energy storage system for frequency regulation, the Energy New Business Laboratory at KEPCO Research Institute installed a 4 MW energy storage system (ESS) demonstration facility at the Jocheon Substation on Jeju Island. And after the successful completion of demonstration operations, a total of 52 MW ESS for frequency regulation was installed in Seo-Anseong (28 MW, governor-free control) and in Shin-Yongin (24 MW, automatic generation control). The control system used in these two sites was based on the control system developed for the 4 MW ESS demonstration facility. KEPCO recently finished the construction of 184 MW ESS for frequency regulation in 8 locations, (e.g. Shin-Gimjae substation, Shin-Gaeryong substation, etc.) and they are currently being tested for automatic operation. KEPCO plans to construct additional ESS facilities (up to a total of about 500 MW for frequency regulation by 2017), thus, various operational tests would first have to be conducted. The high-speed characteristic of ESS can negatively impact the power system in case the 500 MW ESS is not properly operated. At this stage we need to verify how effectively the 500 MW ESS can regulate frequency. In this paper, the effect of using ESS for frequency regulation on the power system of Korea was studied. Simulations were conducted to determine the effect of using a 524 MW ESS for frequency regulation. Models of the power grid and the ESS were developed to verify the performance of the operation system and its control system. When a high capacity power plant is tripped, a 24 MW ESS supplies power automatically and 4 units of 125MW ESS supply power manually. This study only focuses on transient state analysis. It was verified that 500 MW ESS can regulate system frequency faster and more effectively than conventional power plants. Also, it was verified that time-delayed high speed operations of multiple ESS facilities do not negatively impact power system operations. It is recommended that further testing be conducted for a fleet of multiple ESSs with different capacities distributed over multiple substations (e.g. 16, 24, 28, and 48 MW ESS distributed across 20 substations) because each ESS measures frequency individually. The operation of one ESS facility will differ from the other ESSs within the fleet, and may negatively impact the performance of the others. The following are also recommended: (a) studies wherein all ESSs should be operated in automatic mode; (b) studies on the improvement of individual ESS control; and (c) studies on the reapportionment of all ESS energies within the fleet.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.384-389
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• 2004

As the increase of the operation year of nuclear power plants, the probabilities of the degradation of the major facilities and materials in the nuclear power plants are increased. The integrity of those facilities shall be monitored and verified by the non-destructive examination methods with the regulation codes, so called inservice inspection(ISI). The ISI of Yonggwang unit 6 was performed in four different parts, 1) non-destructive examinations for the components, piping weldments and structures, 2) automated ultrasonic examinations for pressure vessels, 3) visual examinations for the interior structures of the reactor, 4) eddy current examinations for the steam generator tubes. As the results, there was no severe indication and all detected indications were evaluated as non-relavent. Especially for the examinations of the piping weldments, PD(Performance Demonstration) was applied as a W examination method defined in the 1995 edition of ASME Code Sec. XI. The implementation of the PD for the piping weld results in an improvement of the reliability of the UT examinations.

• Membrane Journal
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• v.17 no.3
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• pp.197-209
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• 2007

In this study, a multi-staged pilot-scale membrane plant was constructed and operated for the separation of $CO_2$ from LNG-fired boiler flue gas of 1,000 $Nm^3/day$. The target purity and recovery ratio of $CO_2$ required for the pilot plant were 99% and 90%, respectively. For this purpose, we previously developed the asymmetric polyethersulfone hollow fibers and evaluated the effects of operating pressure and feed concentration of $CO_2$ on separation performance[1,2]. The permeation data obtained were also analyzed in relation with the numerical simulation data using counter-current flow model[3,4]. Based on these results, we designed and prepared the demonstration plant consisting of dehumidification process and four-staged membrane process. The operation results using this plant were compared with the numerical simulation results on multi-staged membrane process. The experimental results matched well with the numerical simulation data. The concentration and the recovery ratio of $CO_2$ in the final stage permeate stream were ranged from $95{\sim}99%$ and $70{\sim}95%$, respectively, depending on the operating conditions. This study demonstrated the applicability of the membrane-based pilot plant for $CO_2$ recovery from flue gas.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.3
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• pp.201-209
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• 2004

Important operation parameters and performance of a high temperature ceramic candle filter system were evaluated through a series of demonstration tests at a pilot-scale vitrification plant. At the initial period of each test, due to the growth of dust cake on the surface of ceramic candles, the pressure drop across the filter media increased sharply. After that it became stable to a certain range and varied continuously proportion to the face velocity of off-gas. On the contrary, at the initial period of each test, the permeability of filter element decreased rapidly and then it became stable. Back flushing of the filter system was effective under the back flushing air pressure range of 3∼5 bar. Based on the dust concentrations measured by iso-kinetic dust sampling at the inlet and outlet point of HTF, the dust collection efficiency of HTF evaluated. The result met the designed performance value of 99.9%. During the demonstration tests including a hundred hour long test, no specific failure or problem affecting the performance of HTF system were observed.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.2
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• pp.173-182
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• 2014

Dimethyl ether (DME) is a new clean fuel as an environmentally-being energy resources. DME has similar characteristics to those of LPG and can be substituted Diesel fuel. KOGAS has investigated and developed new innovative DME synthesis process from synthesis gas with KOGAS's own technologies. KOGAS had finished the construction of 10ton/day DME demonstration plant in 2008, we have established the basic design of commercial plant which can produce 3,000ton/day DME. Specifically, an economic model for a commercial DME project will be presented. It accounts for all the major cost factors that are considered in a commercial scale project as the model input for performing cash flow analysis, after which key economic indicators are produced including the internal rate of return (IRR), net present value (NPV). Sensitivity analysis is performed to identify dominant cost factors to the project economics and quantify their impact. The inputs to the economic analysis will be based on representative cost factors from the commercial-scale design of KOGAS' direct DME process supplemented by literature data. Case study results will be presented based on recent commercialization projects.

• Journal of Korean Society on Water Environment
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• v.38 no.6
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• pp.267-274
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• 2022

This paper is a result of research conducted on the 800,000 m³/d capacity of A Water Treatment Plant (WTP) and 400,000 m³/d capacity of B WTP plant in operation in the Nakdong River region. We evaluated the effect of algae broom on the WTP operation based on the running data of both WTP and the data on the pre-oxidation process field test for algae control using sodium permanganate (SPM) at the B WTP. The study results showed that during the algal bloom period, the coagulant dose increased by 102% in A WTP and 58% in B WTP, respectively, and the chlorine dose also increased by 38% and 29%, respectively, which may affect Total trihalomethane (THM) production. Data such as algal populations and Chl-a, residual chlorine and THM, algal populations, and ozone dose appeared also highly correlated, confirming that algal broom affects WTP operations, including water quality and chemical dosage. As a result of the field test of B WTP, THMs appeared lower than that of the control, suggesting the possibility of the SPM pre-oxidation process as an alternative to algae-related water quality management. Furthermore, in terms of GHG emissions due to energy consumption, it was observed that the pre-oxidation process using SPM was approximately 10.8%, which is a very low ratio compared to the pre-ozonation process. Therefore, these results suggest that the SPM pre-oxidation process can be recommended as an alternative to low-carbon water purification technology.

• The Journal of the Convergence on Culture Technology
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• v.4 no.2
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• pp.179-183
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• 2018

Recently, several studies have been conducted on biogas and organic compost production using food waste in an anaerobic digester. In this study, basic experiments were conducted to produce biogas and compost by fermenting food wastes with microbial agents. First, a microbial agent was developed by combining various microorganisms. Then, the amount of generated biogas was identified through a food waste batch experiment. Further, we could maximize and demonstrate biogas production in an anaerobic digester by examining biogas production and composting in a pilot plant.

• Journal of the Korean Society for Nondestructive Testing
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• v.13 no.1
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• pp.29-39
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• 1993

초음파탐상검사는 그 검사결과가 여타 비파괴검사법에 비해 검사자, 검사장비, 절차서 등 검사 시스템에의 의존도가 높으며, 이중에서도 특히 검사자의 능력과 숙련도에 크게 좌우된다. 따라서 검사결과의 신뢰도를 높이기 위해서는 무엇보다도 검사자에 대해 엄격한 자격인정(Qualification)이 필요하다. 초음파탐상검사는 원자력 발전소 기기의 가동전중검사시 가장 많이 적용하는 체적검사법으로써, 결함검출 및 평가의 신뢰도를 확보하기 위하여 최근 관련 기술기준에서는 검사자에 대해 보다 엄격한 자격인정을 요구함과 아울러 초음파탐상검사 시스템(검사자, 장비, 절차서)에 대한 기량검증(Performance Demonstration)까지를 요구하고 있다. 위의 두 가지 요건을 성공적으로 충족시킬 수 있다면, 초음파탐상기술의 신뢰도는 크게 향상될 것이다. 본고에서는 최근 보다 강화된 원전 가동전중검사 초음파탐상검사 요원의 자격인정요건에 대해 자세히 알아봄으로써 관련 국내 기술기준의 제정과 앞으로 국내 원전 초음파탐상 검사요원에 대한 본 자격인정요건의 적용에 대비코자 하였다. 한편, "초음파탐상검사 시스템에 대한 기량검증 요건"은 초음파탐상 검사요원의 자격인정 요건과 밀접한 관계가 있으므로 다음에 별도로 기술코자 한다.

• Journal of Ecology and Environment
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• v.43 no.2
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• pp.246-253
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• 2019

Background: Water use efficiency (WUE) is an indicator of the trade-off between carbon uptake and water loss to the atmosphere at the plant or ecosystem level. Understanding temporal dynamics and the response of WUE to climatic variability is an essential part of land degradation assessments in water-limited dryland regions. Alternative definitions of and/or alternative methodologies used to measure WUE, however, have hampered intercomparisons among previous studies of different biomes and regions. The present study aims to clarify semantic differences among WUE parameters applied in previous studies and summarize these parameters in terms of their definition and methodology. Additionally, the consistency of the responses of alternative WUE parameters to interannual changes in moisture levels in Northeast Asia dryland regions (NADRs) was tested. Results: The literature review identified more than five different WUE parameters defined at leaf and ecosystem levels and indicates that major conclusions regarding the WUE response to climatic variability were partly inconsistent depending on the parameters used. Our demonstration of WUE in NADR again confirmed regional inconsistencies and further showed that inconsistencies were more distinct in hyper- and semi-arid climates than in arid climates, which might reflect the different relative roles of physical and biological processes in the coupled carbon-water process. Conclusions: The responses of alternative WUE parameters to drying and wetting may be different in different regions, and regionally different response seems to be related to aridity, which determines vegetation coverage.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.6
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• pp.743-751
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• 2010

It requires an interim performance assessment for BTL business of the sewerage rehabilitation which continues from 2005 till now. Means, It is necessary to make an interim performance assessment and an analysis of an business effect of the sewerage rehabilitation BTL projects which still continues, and we presented an improvement method of the new sewerage rehabilitation project in future. This paper has conducted an analysis of the business effect for 3 local government BTL projects which are completed and under operation as of now in Jincheon-Gun, Cheongju-Si and Gangjin-Gun. As a method of business effect analysis, we conducted a business effect of the 3 places using the index set which we previously set for the business effect analysis. The index set in this research was sectionalized to an improvement effect of operating wastewater treatment plant, an benefit effect of the direct cost, an benefit effect of the indirect cost and an environment friendly effect. We, in this paper, conducted an business effect analysis for 3 sewerage rehabilitation BTL projects which are completed or under operation recently as a demonstration, however we judge that an business effect analysis shall be conducted in a stage that a significant time for operation has passed since the completion of the construction in order to induce an actual business effect of the sewerage rehabilitation BTL project.