• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.118-122
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• 2010

In order to provide the necessary operation flexibility during the Nuclear power operation, the extension of existing allowed outage time(AOT) is needed. The extension of AOT affects the Nuclear power plant safety. The validity of changed technical specification requirements should be proved by the safety assessments. In this paper, we evaluated the extension of emergency diesel generator AOT for a single inoperable emergency diesel generator(EDG) from 3days to 7days, 10days and 14days. Finally, the AOT extension contributes the NPP performances through decreasing the unexpected plant trips, reinforcing maintenance and avoiding risks due to unnecessary operation mode changes when the NPP is under the surveillance tests or maintenance.

• Journal of the Korean Data and Information Science Society
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• v.11 no.2
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• pp.189-199
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• 2000

A major deficiency of laboratory testing of rock structure is that the structures are limited in size and therefore present a very small and highly selective sample of the rock mass from which were removed. In a typical engineering project, the samples tested in the laboratory represent only a very small fraction of one percent of the volume of the rock mass. In this paper, we calculate the representative orientation of the resultant vector, the measure of the degree of clustering, the volume of rock mass, the trace length of discontinuity spacing under underlying distributions. And we generate the random fracture networks using real data. We propose the calculating the trace length.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.4
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• pp.391-400
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• 2004

Railway curved zone have crucial effects on the speed of train. Length of transition curve is one of the important factor for alignment compatibility estimation in this sections, this value is decided by running speed and Cant. In this study, the extension method of transition curve is evaluated, based on the alignment of Jang Hang-Line, investigated field conditions of the sections in the curves exist. This research result show that changing of transition curve was proved by necessary to approximately two thirds of the curved sections, and method of fixing central point of track centerline and changing radius of curvature minimize the maximum shift in track centerline and deviation of radius, and also may be effective method for alignment suitability and speed up in case overall improvement is difficult.

• Korean Journal of Construction Engineering and Management
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• v.8 no.3
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• pp.125-133
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• 2007

If project time extension were required in the construction projects, either liquidated damages or extension costs should be applied according to causation of the schedule delays. However, in actual cases it is not applied so far according to the contract conditions. The reason why this situation happened Is that function of the present planning and scheduling is not working feasibly. The CPM schedule could not provide a proper solution for apportioning responsibility for the schedule delays. This situation could be considered as breach of contract and will cause potential disputes for schedule delay. Therefore, in this research process based contract administration model for construction delay claim is proposed to prevent schedule delay and solve the claims. The model is based on pro-active management for causation of delay to provide apportionment of responsibility and written evidences.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1384-1388
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• 2009

래스터 기반 DEM 모델을 이용한 수문지형인자의 산정은 DEM의 해상도(셀크기)에 영향을 받으며, 이러한 DEM의 해상도에 따른 불확실성은 강우-유출모델의 결과에 전파되어 모델의 모의결과에 오차를 발생시키는 원인이 된다. 또한 흐름경로의 결정은 수문모델링에서 DEM으로부터 수계를 형성하고 유역을 생성 및 분할하는데 있어 결정적인 역할을 하며, 각 셀의 경사는 흐름방향을 결정하고 흐름길이는 흐름경로를 따라 측정된 거리로서 결정된다. 이러한 모든 일련의 과정들은 셀간의 연산을 통해 이루어지며, 이러한 점에서 DEM의 해상도에 따른 DEM 처리연산 및 수문지형인자의 변동성은 중요한 고려사항이라 할 수 있다. DEM의 해상도에 따른 영향을 규명하기 위해서는 주요 수문지형인자를 대상으로 DEM의 해상도에 따른 민감도를 분석하는 것이 일반적이며, 따라서 본 연구에서는 위천, 황강 및 금호강 유역에 대해 DEM의 셀크기에 따른 유역면적, 유로연장과 최원유로연장, 유역평균경사와 같은 수문지형인자의 변동성을 분석하였다. 셀크기가 증가함에 따라 유로연장 및 최원유로연장이 감소하는 추세는 보이고 있지만 셀크기의 증가로 인해 반드시 흐름길이 및 유로연장이 감소 또는 증가되는 것은 아니며, 더 많은 유역에 대한 적용을 통해 유로연장에 대한 변동을 규명할 필요가 있을 것으로 판단된다. 또한 유역평균경사는 대체로 셀크기 $10\sim30m$에서 가장 큰 감소를 보이고 있으며, 셀크기 30m 이상에서는 감소크기가 점차 완만하게 나타난다. 그리고 셀크기가 증가할수록 유역평균경사에 대한 누가빈도곡선의 기울기는 점차 급해지고 누가빈도가 증가할수로 각 셀크기간의 유역평균경사의 감소에 큰 영향을 미침을 알 수 있다. 이는 비록 유역평균경사에 대한 누가빈도분포의 추세가 모든 해상도에 대해 유사하게 나타나고 있지만 급경사부에 대해서는 데이터 축약으로 인해 유역평균경사에 있어 상당한 감소를 발생시킬 수 있기 때문이라 판단된다.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.305-310
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• 2001

The purpose of this study is to calculate delay damages for contractors. The study has been performed by investigation of delay cost occurrence status and the analysis of subway construction cases. The results of this study are as follows: 1. Delay cost( 1day) equivalent to $0.005\%$ of total construction cost by analysis case studies. 2. Including bank interest, dealy cost is analysed as the following; $1.1\~9.2\%$ of total construction cost in part extension period, $3.3\~11.0\%$ of total construction cost in total extension period. 3. In comparison between liquidated damages and delay cost, liquidated damages account for average 20.1 times of delay costs. 4. Acceleration cost will be calculate on the basis of delay cost calculation method. In the result of this method, acceleration cost is equal to delay cost at least or must be large than delay cost

• Journal of the Korean GEO-environmental Society
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• v.17 no.4
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• pp.39-46
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• 2016

The final stability analysis of the tunnel structure is generally evaluated by performing site monitoring to determine whether or not the measured value through the convergence after the completion of excavation in the face. When the ground conditions are so poor, the reinforcement around the tunnel was applied for enhancing the stability of tunnels. For the additional tunnel crown collapse or excessive displacement have occurred under construction, correlation analysis were performed for the comparison construction and numeric analyses. In this paper, we investigated the collapse types, tunnel collapse were mostly occurs at the crown and they were analyzed because of the geological conditions in the collapse zone. And also, it was analyzed as being correlated in the crown of tunnel exists a fault fracture zone which extends to the surface part. Thus, in case of ground conditions such as fault fracture zone with a tunnel extending from the crown to the surface, the behavior is larger than the behavior predicted by numerical method.

• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.197-198
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• 1999

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.341-349
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• 1996

To improve the dyeability of polyurethane (PU) resin, low molecular weight diols containing dye site in the molecular structure was added as a chain-extender. PU resin were synthesized with the variations in the chain extender, polyol type, and hard segment/soft segment (HS/SS) ratio. When HS/SS ratio is 1.4 and dimethylolpropionic acid(DMPA) or N-butyldiethanolamine (BDEA) was used as a chain extender, because of heterogeneity of reaction mechanical properties were diminished. But when N-methyldiethanolamine (MDEA) was used as a DCE, and HS/SS ratio lowed to 1.3, mechanical properties and dyeability improved. In particular, when linear type 1,4-BD was formulated with MDEA, hydrolysis resistance and mechanical properties of PTMG type PU was improved. And initial elasticity, tensile strength and elongation could be controlled by the variation of HS/SS ratio, DCE mixing ratio of 1,6-HD or NPG.

• Journal of Labour Economics
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• v.44 no.2
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• pp.1-31
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• 2021

This paper estimates the employment effects among 55~59 years old men of delayed mandatory retirement act between 2016 and 2019. Although the positive employment effects appear to have reclined during the period, they have remained non-trivial and may have encroached youth employment. The results suggest that wages should be flexibly adjusted in the market so that labor demand can sufficiently expand to accommodate the increased labor supply among the old without hurting the young.