• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.21-26
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• 2022

Zinc is emerging as a environment-friendly plating material to replace cadmium, which is harmful to the human body, to prevent hydrogen gas penetration or release from metal materials. Electroplating of Zn and Zn alloys, which is usually performed in an aqueous acidic atmosphere, has disadvantages such as low coulombic efficiency, corrosion, and hydrogen release, resulting in industrial use difficult. In this study, a deep-eutectic solvent was synthesized using choline chloride and ethylene glycol. Using this as a solvent, an electrolyte for Zn plating was prepared, and then zinc was plated on the STS 304 substrate. The surface microstructure and roughness were observed using SEM and AFM. The crystal structure of the electro-plated film was analyzed using XRD. Finally, the preventing effects of hydrogen release through Zn-based deep-eutectic plating on the STS 304 substrate were compared with the uncoated substrate.

• Journal of Digital Convergence
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• v.19 no.11
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• pp.365-371
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• 2021

In this study, The Virtual Power Plant (VPP) solution platform considered in this study minimizes the cost and investment risk associated with the construction of power generation and transmission facilities. In addition, it includes a Demand Response (DR) program operation function to meet consumers' electricity demand. With the introduction of VPP, it is possible to provide more eco-friendly and efficient power by responding to changes in consumer load in real time through existing generators and DR programs without large-scale facility investment in power generation and transmission/distribution sectors. In order to link the communication device to the solar power and ESS linkage device, it is necessary to transmit data in the control/state between the device device and the edge system and develop an IoT device and interworking platform (OneM2M).

• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.460-474
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• 2022

The purpose of this study was to explore the perception of the extension of the retirement age perceived by corporation top leaders who are the main agents of employment. As a result of analyzing the interview data by qualitative content analysis, companies centered on manufacturing and construction preferred the elderly to foreign workers and leaders of social service organizations suggested that healthy and capable elderly people should be able to continue to work. However several opinions were also presented against the extension of the retirement age uniformly without considering the circumstances of the company. The passion for work of older workers with higher salary decreased, which concerns that the absence of a retirement system would reduce the vitality of the organization and increase the burden of labor costs. As an alternative to this, there is the opinion that employment can be extended even after the retirement age with the contract and in the form of a commissioned job according to an agreement with the company. Furthermore, it was also suggested that it would be easier not only to maintain employment but also to create jobs for the elderly given the employment flexibility.

• Journal of Platform Technology
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• v.10 no.2
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• pp.20-26
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• 2022

Interest and investment in drones that apply the concept of the 4th industrial revolution and ICT convergence advanced technology are continuing. The purpose of drone operation has been widely spread from the initial military use to the use of various industries such as construction, forestry, facilities, and agricultural support. In these industries, the training of pilots who can actually operate drones is increasing centering on the qualification system. However, the detailed standards including the training place, training place, educational environment, and education method for nurturing pilots are ambiguous, so the education through the oral instruction of the training instructor is continuing at the drone training site. In order to solve this problem, this study conducted a study on a dual control platform in which a training instructor could directly intervene in the pilot's flying drone to execute a map in order to improve the quality of synesthesia, which is essential in the field.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.120-120
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• 2022

우리나라 친환경 에너지 생산의 주요 축을 담당하고 있는 양수발전댐의 홍수 시 정교한 수계운영을 위한 방안으로 강우-유량-댐 수위 매트릭스(이하, PDH Matrix)를 개발하고 양수발전소상-하부댐 연계 운영에 따른 홍수 영향을 분석하였다. 연구 대상지역은 강원도 양양군 서면에 위치하고 있는 국내 최대 양수발전소인 양양양수 발전소로 총 저수용량 92만 m³의 콘크리트 중력식댐으로 유역면적은 약 125 km²이다. 양양양수 발전댐의 수계운영을 위한 PDH Matrix는 지속기간별 강수량 규모에 따른 홍수량 및 댐 최고수위 추정치를 판단할 수 있는 조견표로 강우규모 30 - 360 mm (30분 간격, 12개 강우규모) 및 지속기간 1-24시간 (1시간 간격, 24개 지속기간)인 총 288개의 강우조건별 홍수수문곡선을 개발하였다. 개발된 홍수수문곡선을 입력자료로 기존 댐 운영 방식인 AutoROM을 적용하여 저수지 홍수추적을 HEC-ResSim 모형으로 수행하고 최종적으로 개별 강우사상에 대한 강수량-유량-댐 수위 테이블을 작성하였다. 홍수기 댐 운영에 따른 최고수위는 초기 댐 수위조건에 따라 변동되므로 초기 댐 수위 조건(EL. 115 - 117 m, 1 m 간격)별 PDH Matrix를 각 각 개발하였다. 또한, 양수발전소의 특성상 상부댐으로 양수 또는 발전 방류에 따라 홍수 시 댐의 치수안전성에 미치는 영향이 크므로 상, 하부댐 운영에 따른 홍수영향 분석을 수행하였다. 구체적으로 하부댐에서 상부댐으로 양수 시 시간에 따른 하부댐 저수지의 수위변화 양상을 추정하였으며 극한적 홍수상황을 고려하기 위하여 상부 저수지가 만수인 상황에서 불가피하게 하부댐으로 방류가 필요한 상황에 대비한 홍수기 운영방안을 제안하였다. 본 연구는 하부댐-상부댐을 연계하여 운영하는 양수발전댐의 홍수기 수계 운영 방안을 수립한 첫 연구로 향후 연구에서 개발한 강우-유량-댐 수위 매트릭스(PDH Matrix) 작성 기법을 타 양수발전소 수계 운영 시 활용할 수 있을 것으로 기대된다.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.85-95
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• 2007

In this study, in order to propose the prediction method of the residual settlement of clayey ground improved by vertical drains, a series of numerical analyses for a model ground were carried out using the elasto-viscous consolidation model. And the effects of ground improvement conditions of the ratio of effective radii $(r_e/r_w)$, consolidation pressure $({\Delta}p)$ on normally consolidated state, and the OCR (overconsolidation ratio) on overconsolidated state to reduce the residual settlement in three-dimensional consolidation by vertical drains were investigated by performing a series of numerical analyses. Furthermore, based on the results of a series of numerical analyses for the model ground, the predicting method of the residual settlement of clayey ground with vertical drains and the determination method of the value of OCR required to control the residual settlement within an acceptable value are proposed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.105-115
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• 2010

In this study, as one of solutions associated with the shortage of treatment area of industrial waste and the containment of its harmful components, the bottom ash which is known to be by-products of thermoelectric power plant was selected and its applicability for aggregate of concrete mixture was measured. Hardness test, sieve analysis, water-absorption test and SEM analysis were carried out to investigate the possibility of using bottom ash as a replacement of coarse and fine aggregate. Chemical analyses such as ignition loss test and X-ray incidence were carried out also. In addition, values for slump, strength, permeability, freeze and thaw, and carbonation were evaluated in terms of effects of replacement ratio of bottom ash. As the results, it was found that, though bottom ash is in short supply of fine particles and is in lack of cohesion, these problems can be solved by partially mixing with natural aggregates or improving in a process of production. In addition, bottom ash has not only advantage of durability but also acquirement of general compressive strengths in case that a certain proportion of natural aggregate is applied to mixture, in spite that unit water or chemical admixture should be increased to acquire good workability due to plenty of porosity.

• KDI Journal of Economic Policy
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• v.35 no.4
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• pp.31-61
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• 2013

The purpose of this study is to calculate the economic value of transport demand forecasting risks in the road PPP project. Under the assumption that volatility of the road PPP project value occurs only in regard with uncertainty of traffic volume forecasting, this study calculates the economic value of the traffic forecasting risks in the case of the road PPP project. To that end, forecasted traffic volume is assumed to be a stochastic variable and to follow the Geometric Brownian motion as time passes. In particular, this study attempts to differentiate itself from existing studies that simply use an arbitrary assumption by presenting the application of different traffic volume growth volatility and the rates before and after the ramp-up period. Analysis of the case projects reveals that the risk premium related to traffic volume forecast of the project turns out as 7.39~8.30%, without considering option value-such as minimum revenue guarantee-while the project value volatility caused by transport demand forecasting risks is 17.11%. As the discount rate grows higher, the project value volatility tends to decrease and volatility in project value is always suggested to be larger than that in transport volume influenced by leverage effect due to fixed expenditure. The market value of transport demand forecasting risk-calculated using the project value volatility and risk premium-is analyzed to be between 0.42~0.50, implying that a 1% increase or decrease in the transport amount volatility would lead to a 0.42~0.50% increase or decrease in risk premium of the project.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.84-93
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• 2010

Compaction of backfill material of Underground power lines is difficult, especially under pipeline. so it could cause structural problem because of low compaction efficiency. So various methods have been taken to solve the problem and one of them is CLSM(Controled low-strength material accelerated flow ability). But In other countries, these are already in progress for a long time to research and development and recently on practical steps. But, in our country, study for only general structures, not for underground power line structure that is being constructed at night rapidly. In this study, we performed property tests and indoor & outdoor test (3 cases). The tests showed flow ability reached at the limit construction(160 mm) flowability by 9 to 15 minute after starting to mix, and construction buoyant is lowering after placing CLSM by 70 % of theoretical buoyant that is calculated by unit weight of material. In this paper, we performed indoor tests and outdoor tests to estimate mechanical properties and to suggest construction method(using batch plant, setting spacer at 1.8 m and placing at 2m) for CLSM that using surplus soil. And the test showed good results for construction quality, workability and structure safety.

• Journal of the Economic Geographical Society of Korea
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• v.11 no.4
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• pp.580-599
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• 2008

This paper aims at examining the existence and characteristics of regional difference in project finance in Korea. Main results of this paper are as follow. Firstly, regional difference in project finance between capital region and local can be seen partially. However, their characteristics are different from corporate finance. ANOVA tests show significant differences of excess interest rate occur in case of commercial real estate projects and significant differences of contracted terms occur in case of residential real estate projects carried out by local banks. Secondly, key factors causing the regional differences in project finance are asymmetric information for cash flow generated by the project between the capital region and local. Especially, regional differences in project finance are different from those in corporate financing because of local banks$^{\circ}{\phi}$ behaviors. They follow and act as the passive members of nationwide banks in case of the capital region projects. Thirdly, prepaid sale system and the guarantee system depending on construction companies dilute the regional differences in project finance in case of residential real estate projects. Although these systems contributed rapid growth of project finance, they may be the main factors distorting project finance market which lead to financial crisis. In these context, policy implications may be derived in order to solve the confronted problems of project finance market.