• 한국산학기술학회논문지
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• 제19권12호
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• pp.653-659
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• 2018

공사비의 정확한 예측은 프로젝트 성공의 핵심 요소이다. 그러나 도면, 시방서, 공사비 산출내역서 등이 아직 불완전한 기획단계의 경우 신속하고 정확하게 공사비를 산출하기가 용이하지 않다. 또한 프로젝트의 기획단계에서 정확한 공사비 예측은 프로젝트의 타당성 조사 및 성공적인 완료에 중요하다. 따라서 프로젝트 정보가 제한적 일 때 사업 초기에 공사비를 정확하게 예측하기 위해 다양한 기법(회귀분석, 인공신경망, 사례기반추론, 유전자알고리즘, 몬테카를로시뮬레이션, 빌딩정보모델링)이 적용되고 있다. 공사비 예측에 영향을 미치는 많은 요소가 있다. 본 논문에서는 7개(대지면적, 연면적, 지하층수, 지상층수, 주동수, 전체세대수, 공사기간)의 건축개요를 독립변수로 사용하는 다중회귀모델(후진제거법)로 공사비 예측치를 제시한다. 다중회귀모델을 이용한 지역주택조합사업 공사비의 예측 결과 오차율은 4.87%로 나타났다. 이는 지역주택조합사업의 기획단계에서 공사비 예측에 관한 연구가 없어 비교가 불가능하나, 기존에 사용하던 단위면적에 대한 단가산정방식에 비하여 높은 예측 정확도를 가짐으로써, 향후 지역주택조합사업의 기획단계에서 공사비 산출업무에 적용 가능성이 높고, 지역주택조합사업의 사업예산 수립에 기여할 수 있을 것으로 판단된다.

• Journal of Power Electronics
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• 제16권6호
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• pp.2231-2242
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• 2016

A simplified model predictive control method is presented in this paper. This method is based on a future reference voltage vector for a three-phase four-leg voltage source inverter (VSI). Compared with the three-leg VSIs, the four-leg VSI increases the possible switching states from 8 to 16 owing to a fourth leg. Among the possible states, this should be considered in the model predictive control method for selecting an optimal state. The increased number of candidate switching states and the corresponding voltage vectors increase the calculation burden. The proposed technique can preselect 5 among the 16 possible voltage vectors produced by the three-phase four-leg voltage source inverters, based on the position of the future reference voltage vector. The discrete-time model of the future reference voltage vector is built to predict the future movement of the load currents, and its position is used to choose five preselected vectors at every sampling period. As a result, the proposed method can reduce calculation load by decreasing the candidate voltage vectors used in the cost function for the four-leg VSIs, while exhibiting the same performance as the conventional method. The effectiveness of the proposed method is demonstrated with simulation and experiment results.

• 한국BIM학회 논문집
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• 제7권2호
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• pp.16-24
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• 2017

It is very important to estimate accurate construction total cost needed early in the project. In the initial phase of the design, the project cost estimates are determined by total quantity from design documents and the variables that affect the calculation of the total cost of the project. In order to determine accurate total construction cost, the contractor has to produce detailed quantity information based on the drawings and specifications. The process of preparing quantification and cost estimation documents is still being worked out manually, and a lot of errors have been occurred in many cases. Recent advances in information technology have led to the BIM based quantity takeoff and cost estimation. However, there are some limits to the extent to which the current specifications for BoQ documents are computed from BIM model. This research analyze the current BoQ cases and analyze how to make quantity takeoff possible through BIM. The study defined five levels of quantity category that could be produced by BIM. Only about 40% or indirectly usable items can be used when information is extracted to BIM modelling. This is very insufficient to fill out the BoQ. The BoQ document structure quantity takeoff specifications should be simplified in order to BIM based cost estimation more efficiently.

• 한국건설관리학회논문집
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• 제20권6호
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• pp.89-97
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• 2019

최근 건설프로젝트에서 BIM의 도입이 활발히 이루어지고 있다. 특히 견적단계에서의 BIM의 도입은 공사비 예측의 정확성 향상 및 견적자의 업무를 절감할 수 있는 효과가 기대된다. 하지만 현재의 물량산출 과정과 내역서 작성과정은 상당부분 수작업으로 이루어지고 있다. 또 현행 내역서의 내역항목을 만족시키기 위해서는 BIM 모델이 매우 상세해져야 하는 문제점이 있다. 이에 본 연구는 LOD기준을 분석하여 BIM 모델의 표현 수준에 따라 산출될 수 있는 내역항목을 도출함으로써 현행 내역서의 개선방향을 BIM 모델의 LOD 측면에서 도모하고자 한다. LOD기반 내역항목 분석을 위해 내역항목 등급을 A,B,C등급으로 나누었다. 따라서 본 연구에서는 실시설계 단계에서 LOD 수준 따라 산출될 수 있는 내역항목의 수와 해당항목이 차지하는 금액 비율을 각 공종별로 검토하였다. 실시설계 단계에서 주요 개선 등급인 B등급에서 가장 많은 항목을 차지한 공종은 창호 및 유리공사이며, 가장 많은 금액을 차지한 공종은 철근콘크리트 공사로 분석되었다. 추후 항목비율이 높은항목과 금액비율이 높은항목별 적절한 개선방안제시가 필요할 것으로 판단된다. 본 연구의 결과는 BIM 견적이나 현행 내역서 체계 개선을 위한 기초자료로서의 역할을 기대 할 수 있을 것으로 판단된다.

• KIEAE Journal
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• 제11권4호
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• pp.47-54
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• 2011

Construction companies find it increasingly necessary to reduce the cost as the construction market has been suffering from a depression and the industrial environment has been changing fast lately. The cost cut demands the productivity management of the field operations, which can be made feasible by assigning an appropriate number of managers on the construction site. However, previous studies are focused on the labor productivity and construction companies take into account only the revenue per worker in organizing the staff. The purpose of this study is to research the model for calculating the field management manpower in accordance with the characteristic of project and site conditions which are usually considered in the beginning of the construction project. The data about apartment building projects of domestic large constructors and factors related to them were statistically analyzed. The results of this study can be used to calculate the necessary field management manpower in accordance with the characteristic of project.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.135-136
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• 2011

A standard of estimation is used as a basis for estimating the predetermined amount of public construction. However, they raise several points of reasonable labor to be presented to a standard of estimation. For this reason, it is difficult to make a reasonable and efficient estimation of the costs, and this situation presents an urgent need for an accurate way of making such a calculation.This study analyzed the productivity of reinforced concrete work by the CYCLONE model, and the estimated optimal labor through sensitivity analysis, and presented the model on the number of optimal labor through sensitivity analysis.

• Journal of Information Processing Systems
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• 제17권6호
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• pp.1127-1137
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• 2021

Given the different effects of agricultural mechanization on various stages of wheat planting in Henan, this article selects 78 observation samples from Henan, a major wheat-growing province. It uses different research methods (multiple linear regression, social network analysis model, multi-layer sensory nerves network) to conduct a comparative study, and the calculation results of the model show that the experimental results have a strong convergence and consistency. Agricultural mechanization services have significant effects on the three stages of wheat planting: harvesting, plowing and sowing. A higher degree of mechanized service in several stages can reduce the cost of growing wheat on family farms.

• Journal of Welding and Joining
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• 제15권4호
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• pp.63-69
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• 1997

Welding distortion is more serious problem than any other problems caused by welding process, especially, in the heavy-industrial place. These welding distortions are caused by nonuniform heating and cooling of metal during and after welding operations. And these distortion quantities are must be known to worker in production line because distorions are important role in assembling part. Therefore an analytical model to explain and predict the welding distortion are needed. A numerical analysis of welding distortion which is inelastic behavior of weldment would require the three dimensional calculation. But computing time and memory would be very large, and the resulting cost might be unacceptable. Therefore we use a numerical technique for two dimensional analysis in the section normal to the weld direction of weldment under an assumption of quasi-stationary conditions. But the result of the calculation under two dimensional(plane strain) assumption was not satisfied as compared with experimental result. This paper proposed a technique for analysing the welding angular distortion by using a constraint boundary condition on the two dimensional finite element model. The simulation results revealed that the constraint boundary model could more reasonably describe the welding distortion than the plane strain model did.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.843-848
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• 2011

Planning and construction of railway for high speed trains up to 400 km/h are recently driven in Korea. High speed train is one of the environment-friendly fastest mass transportation means but its noise generated by rolling, traction and aerodynamic mechanism can cause public complaints of residents nearby railways. To cost-effectively prevent the troublesome noise in a railway planning stage, the rational railway noise prediction method considering the characteristics of trains as well as railway structures should be required but it is difficult to find authentic methods for Korean high speed trains such as KTX and KTX-II. In this study, we propose a framework of our own railway noise prediction model emitted by Korean high speed trains over 250 km/h based on the recent research results carried out in EU countries. The model considers railway sound power level using several point sources distributed in heights as well as tracks, whose detail speed- and frequency-dependent emission characteristics of Korean high speed trains should be determined in near future by measurement or numerical analysis. The attenuation during propagation outdoors is calculated by the well-known ISO 9613-2 and auxiliary methods to consider undulated terrain and wind effect.

• 한국축산식품학회지
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• 제18권4호
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• pp.285-291
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• 1998

Adsorption isotherms of water vapour for infant formula milk powders manufactured by P. M. and N company in Korea were measured at temperatures between 20, 30 and 40$^{\circ}C$ using COST-90 modified method. Results showed that the isotherms were sigmoidal in shape. The adsorption isotherms of milk powder were depending on the temperature and products. The BET-model were applied and analyzed to compare the experimental value. It was found that the BET-model is fitted with measuring data. Sample P showed the lowest monolayer value and sample N showed the highest. Isosteric heat obtained upon application of BET-model was calculated in this field of temperature using the Clausius-Clapeyron equation. It is suggested that the usage of the BET-model to estimate the heat of water sorption in infant formula milk powder should be in agreement with the results from COST-90 project.