• 경영과학
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• 제22권1호
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• pp.15-26
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• 2005

The bootstrap is a method of computational inference that simulates the creation of new data by resampling from a single data set. We propose a new job for the bootstrap: generating inputs from one historical trace using Threshold Bootstrap. In this regard, the most important quality of bootstrap samples is that they be functionally indistinguishable from independent samples of the same stochastic process. We describe a quantitative measure of difference between two time series, and demonstrate the sensitivity of this measure for discriminating between two data generating processes. Utilizing this distance measure for the task of generating inputs, we show a way of tuning the bootstrap using a single observed trace. This application of the threshold bootstrap will be a powerful tool for Monte Carlo simulation. Monte Carlo simulation analysis relies on built-in input generators. These generators make unrealistic assumptions about independence and marginal distributions. The alternative source of inputs, historical trace data, though realistic by definition, provides only a single input stream for simulation. One benefit of our method would be expanding the number of inputs achieving reality by driving system models with actual historical input series. Another benefit might be the automatic generation of lifelike scenarios for the field of finance.

• 한국조경학회지
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• 제26권2호
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• pp.155-165
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• 1998

Cultural-historical places, due to their strong symbolic sense of place shared in various people, have important impacts on people's cognitive and emotional reactions. Especially, the visual characteristics of surrounding areas of cultural -historical places directly influence the way the places are perceived, because they function as a visual background of the places. This study examined how the visual characteristics of surrounding landscape of cultural-historical places nfluenced the perception of the places. The visual characteristics of the surrounding landscape was minipulated by a computer simulation in the two aspects; quality and scale. The quality of the simulated landscape was divided by two kinds : natural and artificial . The scale of the simulated landscape was classified by three kinds : 1/3 of the middle ground, 2/3, and 3/3. Specifically, in each photo simulation, simulated natural or artificial background was introduced up to 1/3, 2/3 or the full height of historic monument. After a computer simulation, people's cognitive and emotional reactions to the simulated slides were investigated. The results showed that the quality of surrounding landscape have a great impact on all the cognitive and emotional reactions investigated. On the vontrary, the scale of surrounding landscape was found to habve an impact on partial reactions, such as all the emotions, part of the cognitions, and visiting preference only. The results revealed that the visual characteristics of surrounding landscape should be considered as the crucial elements in planning of cultural-historical places. Based on the study results, several suggestions were made for the landscape planning and conservation for cultural-historical places and historic cities.

• 한국건설관리학회논문집
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• 제3권2호
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• pp.107-113
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• 2002

건설공사의 실적관리는 건설곱사의 실적증명을 위한 프로세스의 일부에 건설업체가 직접 참여함에 따라 자료의 신뢰도 확보 및 건설업체 방문비용 등 많은 문제점을 가지고 있다. 따라서 본 연구는 현재의 실적관리 프로세스를 IDEF 방법론에 따라 분석하여, 건설실적 정보의 신뢰도를 확보할 수 있고, 건설업체의 발주기관의 방문비용을 절감하며, 관련조직의 업무 효율화 및 행정의 투병성을 높일 수 있는 개선모델을 제안하는 것이다. 프로세스 분석에는 IDEF 방법론을 사용하였고, 개선효과 검증을 위하여 시뮬레이션 도구를 활용하였다. 연구결과 개선모델은 현행모델보다 매우 생산성이 높은 것으로 나타났으며, 특히 발주기관보다 건설업체에서 더욱 효과가 있는 것으로 나타났다.

• 물과 미래
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• 제7권1호
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• pp.71-77
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• 1974

This paper reviews several different single site generation models for further development of a model for generating the Synthetic sequences of streamflow in the continuous streams like main streams in Korea. Initially the historical time series is looked using a time series technique, that is correlograms, to determine whether a lag one Markov model will satisfactorily represent the historical data. The single site models which were examined include an empirical model using the historical probability distribution of the random component, the linear autoregressive model(Markov model, or Thomas-Fiering model) using both logarithms of the data and Matala's log-normal transformation equations, and finally gamma distribution model.

• 한국지진공학회논문집
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• 제25권2호
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• pp.59-69
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• 2021

Historical records of earthquakes are generally used as a basis to extrapolate the instrumental earthquake catalog in time and space during the probabilistic seismic hazard analysis (PSHA). However, the historical catalogs' input parameters determined through historical descriptions rather than any quantitative measurements are accompanied by considerable uncertainty in PSHA. Therefore, quantitative assessment to verify the historical earthquake parameters is essential for refining the reliability of PSHA. This study presents an approach and its application to constrain reliable ranges of the magnitude and corresponding epicenter of historical earthquakes. First, ranges rather than specific values of ground motion intensities are estimated at multiple locations with distances between each other for selected historical earthquakes by reviewing observed co-seismic natural phenomena, structural damage levels, or felt areas described in their historical records. Based on specific objective criteria, this study selects only one earthquake (July 24, 1643), which is potentially one of the largest historical earthquakes. Then, ground motion simulations are performed for sufficiently broadly distributed epicenters, with a regular grid to prevent one from relying on strong assumptions. Calculated peak ground accelerations and velocities in areas with the historical descriptions on corresponding earthquakes are converted to intensities with an empirical ground motion-intensity conversion equation to compare them with historical descriptions. For the ground motion simulation, ground motion prediction equations and a frequency-wavenumber method are used to consider the effects of possible source mechanisms and stress drop. From these quantitative calculations, reliable ranges of epicenters and magnitudes and the trade-off between them are inferred for the earthquake that can conservatively match the upper and lower boundaries of intensity values from historical descriptions.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 추계 학술논문 발표대회
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• pp.141-142
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• 2012

Estimating the productivity of labor has relied on the experience and intuition of an estimator, or productivity data, such as standard in practical estimation. However, when new technologies and new construction methods employed in the construction industry, Dependence of a quantity surveyor's intuition is increased. This is because of the lack of a systematic methodology which models, estimates, and measures the labor productivity, Due to the historical productivity data is unavailable. Even thought project history data contains information that is important to predict the performance of a project, It can not provide valuable information to model, estimate, and measure the labor productivity. This is because 1) the absence of the productivity measurement system with consistency, 2) the difficulty of reusability of historical data collected. Therefor, this study suggests a methodology which build a productivity model by measuring the productivity of labor and collecting the historical data systematically. In addition, this methology is applied to develop a productivity model of shop-drawing and manufacturing process using descrete event simulation.

• Smart Structures and Systems
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• 제4권2호
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• pp.247-259
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• 2008

The potential use of Cu-based shape memory alloys (SMA) in retrofitting historical monuments is investigated in this paper. This study is part of the ongoing work conducted in Tunisia within the framework of the FP6 European Union project (WIND-CHIME) on the use of appropriate modern seismic protective systems in the conservation of Mediterranean historical buildings in earthquake-prone areas. The present investigation consists of a finite element simulation, as a preliminary to an experimental study where a cantilever masonry wall, representing a part of a historical monument, is subjected to monotonic and quasi-static cyclic loadings around a horizontal axis at the base level. The wall was retrofitted with an array of copper SMA wires with different cross-sectional areas. A new model is proposed for heat-treated copper SMAs and is validated based on published experimental results. A series of nonlinear finite element analyses are then performed on the wall for the purpose of assessing the SMA device retrofitting capabilities. Simulation results show an improvement of the wall response for the case of monotonic and quasi-static cyclic loadings.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.393-399
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• 2009

This paper introduces an automated tool named Advanced Stochastic Schedule Simulation System (AS4). The system automatically integrates CPM schedule data exported from Primavera Project Planner (P3) and historical activity duration data obtained from a project data warehouse, computes the best fit probability distribution functions (PDFs) of historical activity durations, assigns the PDFs identified to respective activities, computes the optimum number of simulation runs, simulates the schedule network for the optimum number of simulation runs, and estimates the best fit PDF of project completion times (PCTs). AS4 improves the reliability of simulation-based scheduling by effectively dealing with the uncertainties of the activities' durations, increases the usability of the schedule data obtained from commercial CPM software, and effectively handles the variability of the PCTs by finding the best fit PDF of PCTs. It is designed as an easy-to-use computer tool programmed in MATLAB. AS4 encourages the use of simulation-based scheduling because it is simple to use, it simplifies the tedious and burdensome process involved in finding the PDFs of the many activities' durations and in assigning the PDFs to the many activities of a new network under modeling, and it does away with the normality assumptions used by most simulation-based scheduling systems in modeling PCTs.

• 한국CDE학회논문집
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• 제20권4호
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• pp.431-442
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• 2015

Currently, a BIM-based quantity takeoff (QTO) system is mainly focused on architectural projects. To perform this, diverse quantity takeoff methods such as an object-based automatic quantity takeoff, manual quantity and base functions of calculation have widely been utilizing. However, since BIM library for road projects includes structural elements associated with alignment, it is necessary to establish cost estimation system interlocked with historical cost using 3D library by each unit length. Accordingly, the aim of this study is to develop cost estimation model with using a historical cost approach so that it can be utilized in construction planning based on the BIM library for road projects. For this, based on the BIM library for road, the standardized quantity is estimated, and a process for calculating historical cost and a verification model with a 5D simulation was developed by mapping a WBS code with each BIM library object. This can be applied during the approximate cost estimation process in a project planning and an initial design phase for road projects. Besides, it is expected that these results will be utilized in constructing an optimal historical cost estimation process for project libraries.

• 한국수자원학회논문집
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• 제35권6호
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• pp.763-777
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• 2002

본 연구의 목적은 간헐 수문사상인 시간강수계열의 구조적 특성을 고찰하여 강수량 모의발생을 위한 추계학적 모형을 개발하는 것이다. 이를 위하여 본 연구에서는 강수발생과정에 대한 추계학적 모형은 이재준과 이정식(2002)이 개발한 추계학적 모형을 이용하였으며, 강수량과정을 위하여 사상내의 시간강수량을 비정상 1차 자기회귀모형으로 기술하였다. 시간강수계열의 강수발생과정과 강수량과정을 조합하면 시간강수사상의 발생패턴과 사상기간내의 강수의 종속구조를 모의할 수 있는 시간강수계열에 대한 모의모형이 얻어지며, 이 모형의 적합성을 구명하기 위해 서울을 대상으로 하여 실적강수자료를 분석하였다. Monte Carlo 모의결과는 모형이 사상기간내의 강수강도, 지속 기간, 크기의 주변 및 조건부 분포를 잘 재현하고 있음을 보여주었다. 실적 및 모의 자료에 대한 자기상관함수도 비교적 작은 시간지체에서는 유사하였다