• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1067-1071
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• 2008

장기적인 수자원정책을 수립하기 위해서는 강수, 증발산, 유출 등의 물수지의 변동성을 평가하는 것이 중요하다. 특히 기후변화로 인한 기온 증가는 증발산량에 영향을 미칠 것이다. 따라서 기후변화에 따른 수자원의 영향을 신뢰성 있게 평가하기 위해서는 증발산량의 산정방법에 대한 불확실성을 평가하는 것이 필요하다. 본 연구에서는 다섯 가지의 증발산량 산정방법에 대해 기온 및 강수변화에 따라 증발산량 계산과 유출량산정에 미치는 영향을 평가하였다. 안동댐 유역에 대해 준분포형 수문모형인 SLURP를 이용하여 기온과 강수변화에 따른 5가지 증발산량 산정방법의 민감도를 분석하였다. SLURP 모형에서는 Penman-Monteith method, Morton CRAE method, Spittlehouse/Black method, Granger method, Linacre method의 다섯 가지방법을 제시하고 있고, 관측 자료에 대해 검 보정을 수행한 결과 5개의 증발산량 산정법 모두 안동댐 유역에 대해 잘 모의하는 것으로 나타났다. 기온과 온도를 변화시킨 합성시나리오에서 Linacre 방법이 다른 방법들과 비교하여 높은 민감도를 나타내었는데 증발산량 산정법별 구조적 차이가 원인 것으로 판단되어 추가적인 연구가 진행 중이다. 결과적으로 각 증발산량 산정방법에 따른 민감도 차이는 기후변화 영향평가 결과의 불확실성을 제시하는 척도가 될 것이다.

• Journal of Korean Society of Transportation
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• v.26 no.5
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• pp.217-226
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• 2008

The term, travel-time reliability, refers to variations in journey time that travelers cannot predict. The purpose of this paper is to suggest a standard way to measure travel time reliability. A modified buffer time indicator is proposed. The index is represented by the difference between planned and actual travel times based on lognormal type travel time distribution. Using this framework, a constant function for railways and a negative parabola function for roads are discussed. The model developed is applied to the real data of Korean road and rail usages to empirically verify the methodology proposed. In this process, the unit value of travel time reliability for each group is estimated. The result of this research is expected to be helpful of conducting more cautious economic feasibility studies of transport.

• KDI Journal of Economic Policy
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• v.9 no.2
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• pp.25-37
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• 1987

본(本) 연구(硏究)의 목적(目的)은 우리나라에 장시간근로가 행해지고 있는 데 원인을 규명함에 있다. 이를 위하여 초과근로시간(超過勤勞時間)과 신규고용간(新規雇傭間)의 상대적(相對的) 노동비용(勞動費用)을 비교 분석하였으며 분석방법으로는 이론모형(理論模型)의 활용(活用) 대신에 수식(數式)을 이용하여 비용을 직접 계측(計測)하였다. 분석을 위하여 근로자(勤勞者)는 소득을 증대시키기 위하여 기업의 초과근로시간을 받아들이는 것으로 가정되었다. 통계자료는 노동부의 각종 공식 발표통계와 기업별(企業別) "서베이" 자료를 사용하였다. 분석결과에 따르면 우리나라 전체로 볼 때 초과근로시간(超過勤勞時間)에 따른 노동비용(勞動費用)이 신규고용(新規雇傭)의 경우에 따른 비용의 72%에 달하였다. 초과근로시간으로 인한 노동비용(勞動費用)이 상대적으로 낮은 주된 이유는 기업(企業)의 임금체계상(賃金體系上) 정규임금(正規賃金)의 비중(比重)이 낮고 비임금노동비용(非賃金勞動費用)이 높은 데 있었다. 한편 산업별(産業別)로는 섬유(纖維) 의류(衣類) 신발 등 비교적 노동집약적(勞動集約的)이며 저임금부문(低賃金部門)이 집중되어 있는 산업에서 신규고용(新規雇傭)에 대한 초과근로시간의 상대적(相對的) 노동비용(勞動費用) 비율(比率)이 낮게 나타났으며 기업별(企業別)로는 규모가 클수록 이 비율이 낮게 나타났다. 이러한 결과에 의하면 기업의 임금체계를 점차 기본급(基本給) 위주로 바꾸어 나가고 실업보험제(失業保險制)를 도입하여 기업으로 하여금 근로시간(勤勞時間)보다는 고용수준(雇傭水準)을 경기변동에 맞추어 조절하도록 도와주는 것이 바람직하다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.121-133
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• 1993

Presented is a study on the establishment of a method of advanced reliability analysis for the realistic analysis and design of reinforced concrete(RC) structures. Considerable variabilities exist in concrete structures due to random nature of concrete materials and member dimensions. The present study analyzes first the uncertainties in concrete, reinforcements and member dimensions and then a method is proposed to determine the probability uncertainties of basic variables. The limit state equations are also proposed for the RC members with axial compression and bending and RC footings. The advanced invariant second-moment method is applied to analyze those structures. The present study provides an important base for realistic reliability analysis of RC structures.

• Ocean and Polar Research
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• v.31 no.2
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• pp.189-198
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• 2009

Passive air samplers with polyurethane foam (PUF) disks were employed to determine seasonal gas phase variation of polycyclic aromatic hydrocarbons (PAHs) in ambient air on Anmyeon island from March 2007 to January 2008. Sum of 13 PAHs ranged between $3.5\;ng/m^3$ and $27.6\;ng/m^3$. Total PAHs during the heating season was 6.2 times higher than non-heating season. The dominant PAHs components during sampling periods were low and middle molecular weight PAHs including phenanthrene, fluoranthene, pyrene and chrysene. Gas exchange fluxes of PAHs across the air-water interface of the Yellow Sea were calculated using a modified two-film exchange model. PAHs fluxes ranged from $196\;ng/m^2/d$ net volatilization during summer to $3830\;ng/m^2/d$ net absorption during winter. Passive air sampler provides a convenient and cost-effective tool for measuring averaged gas phase PAHs, which was successfully used for calculation of gas exchange flux of PAHs in the Yellow Sea.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2335-2341
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• 2009

High technique growth of modem times and high industrial facility in consequence of buildings demand for electric power of an extensive scale with stability supply and maintenance of high quality. But, power system always have risk of network contingency. When power system break out disturbance, it circumstantially happen like uncontrolled loss of load developing from of cascading. Severely which would be raised wide area blackout, plan to prevent, which make stability through a little of load shedding and multi-level UnderVoltageLoadShdding should work. This paper presents target, sensitivity of bus voltage have choose appropriating load shedding location and load shedding decision making logic with considering rate of change of voltage have studied multi-level under voltage load shedding scheme. Calculation of rate of change of voltage applied method of least square. As a result, we are studied an dynamic analysis of 2008 summer peak data. We have been known that network analysis is a little development and developing UnderVoltageLoadShedding scheme.

• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.56-66
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• 2014

In this paper, the solar cell need the characteristic interpreting because the solar cell changes greatly according to the isolation, temperature and load in the photovoltaic development. Moreover, to get many energy in photovoltaic development need the position tracking of the sun according to the environment change and it is necessary to control the output of solar cells up to the time. Simulation and composed microprocessor and sensor chip an power conversion system with boost converter to experiment results are performed to prove the analysis of the converter operation, and to show the possibility of energy harvesting and photovoltaic development need the position tracking small capacitance, the boost rate of boost converter was similar to 167 percent.

• The Korean Journal of Quaternary Research
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• v.4 no.1
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• pp.27-40
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• 1990

$^{14}C$ age dating by AMS (accelerator mass spectrometry) technique was performed on twenty five small sized fossil shells and one peat taken from the sixteen piston cores in the southern and southeastern Korean Sea. AMS technique is available to date only a few milligram of amorphous carbons compare than conventional dating technique. It is described in detail of sample pre-treatment and experimental, and applied to the reconstruction of the sea level changes since the late Pleistocene in the Korean Sea. Dated age ranges from 520$\pm$100 to older than 33,500 years. Sedimentary facies in the study area represents a different environmental set which is affected by sea level fluctuation since the late Pleistocene.

• The Korean Journal of Applied Statistics
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• v.15 no.1
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• pp.45-55
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• 2002

The 2-level rotation design based on 3 rotation groups is discussed in view of Monthly Retail Trade Survey conducted by the Bureau of Census in U.S., and composite estimators for population characteristics are concerned. The generalized composite estimators and the recursive composite estimators are presented at 2-level rotation design with design gap and variance formulas for the composite estimators are provided. Also under the response variability related with covariance structure and correlation structure from repeated response, relative efficiencies of the composite estimators are compared.

• Journal of Adhesion and Interface
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• v.12 no.2
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• pp.56-61
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• 2011

In the present study, glucose-sensitive hydrogels using phenylboronic acid (PBA) without glucose oxidase and catalase were prepared. The swelling-shrinking behavior of the hydrogel according to the variation of pH and glucose and ionic concentrations was investigated. The swelling ratio of the hydrogel containing PBA increased with increasing the glucose concentration and the volume was very sensitively varied with the pH. However, the ionic concentration did not change significantly the relative swelling ratio on the hydrogel, indicating that the hydrogel was dimensionally stable.