• 한국건설관리학회논문집
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• 제15권1호
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• pp.101-110
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• 2014

2013년 국토교통부에서는 현 정부의 주요 국정과제인 행복주택 사업의 일부를 모듈러건축 시스템으로 시범공급하겠다라고 밝혔다. 이처럼 모듈러 건축에 대한 정부의 적극적인 의지와 함께 모듈러 건축시장의 규모도 점차 확대되고 있다. 현재 모듈러건축의 주요 문제점으로 설계-제작단계에 있어 자재 및 부품의 표준화 또는 규격화 미비가 거론된다. 이때, 모듈러건축은 기존의 타공법에 비해 재료비의 비중이 16~17% 높은, 전체공사비의 60%를 차지 할 정도로 자재관리가 중요하다고 판단된다. 하지만, 설계상의 표준화 또는 규격화의 미비로 제작단계의 자재 손실율이 높아지게 되고, 이에 따른 건설폐기물 뿐만 아니라, 재료비 증가에 따른 전체 공사비도 증가하게 된다. 본 연구에서는 벽체 마감자재 중 석고보드 자재에 대한 손실율을 최소화 할 수 있는 최적화 알고리즘을 개발하여 대상 사례의 주요 모듈에 대해 검증하고자 한다. 이를 통해, 자재의 낭비적인 요소를 최소화하여 친환경 건축에 기여할 뿐만 아니라, 현 모듈러건축의 단점으로 인지되고 있는 고비용의 경제성 문제를 해소하는데 기여할 수 있을 것으로 기대한다.

• 한국기계가공학회지
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• 제19권3호
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• pp.29-35
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• 2020

This paper studies the main parameters of tube-to-bar dissimilar material and shape friction welding for piping materials. The weldability of joint parts was investigated with respect to tensile tests, micro-Vickers hardness, the bond of area, and optical microstructure. The specimens are tested as-welded. Optimal welding conditions are n = 2000 rpm, HP = 50 MPa, UP = 100 MPa, HT = 5 sec, and UT = 10 sec when the metal loss (Mo) is 11 mm. Moreover, the same two materials for friction welding are strongly mixed with a well-combined structure of micro-particles without any molten material, particle growth, or defects. Therefore, the expected result of dissimilar material friction welding includes a reduction of cost and material in the welding process.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.573-580
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• 2024

Recently, the special alloy, for instance, such as Monel and Inconel, is used for valves, bolt/nuts, and fittings in semiconductor facility, FCEV(fuel cell electric vehicle) and hydrogen gas station, to reduce the hydrogen embrittlement. Even though the Monel material has high cost, it is recommended to use for the cases of ultra high pressure, ultra high leak-proof and so on. The purpose of this study is to investigate the characteristics of Monel material within elastic limit through the comparative analysis when Monel material is extruded or drawn. As the results, the deformation of Monel material was increased as the number of pass was increased, further, the deformation of Monel material by drawing was larger than that by extrusion. In the safety factor, the case that load is less than 420kN, the plastic deformation due to drawing could be happened faster than that due to extrusion. However, the case of more than 420kN, it showed that the plastic deformation for extrusion and drawing was almost similar.

• 농업과학연구
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• 제36권2호
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• pp.233-244
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• 2009

This study analyzed the income of orange farming of Lichuan, Jiangxi Province in China. Using a questionnaire, 36 farmhouseholds of Lichuan were surveyed. The results are as follows. First, through the investigation of Lichuan orange farming farmhouseholds, we know that the direct expenses of Lichuan orange is around 2,250 RMB/10a and the direct expenses per household's are about 32,000 RMB. The average production of Lichuan orange is 1,548 kg/10a and the income is around 2,200 RMB/10a. The results showed that in Lichuan area orange farming benefit is more than rice so orange farming has been increasing. Second, the direct expense of Lichuan orange farming, 91% is material cost, 8% is labor cost, depreciation cost is only 1.4%. This result show that orange farming in Lichuan is very labor intensive. Third, there are a lots of young orange trees in Lichuan, so income would be increasing through the year.

• 건축역사연구
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• 제7권3호
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• pp.27-51
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• 1998

One of the characteristics of a good construction is efficiently to use material and manpower related in the construction. From the preplanning stage to the completion one, a program planner must sufficiently consider the whole field of construction in terms of cost. The estimating account books were written and left in the Construction of the Kyongwoon Palace reconstructed in the beginning of 20th century. Trough those books and other related documents, this paper has been concentrated on the estimated, executed cost of woodwork in those days.

• Transactions on Electrical and Electronic Materials
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• 제18권2호
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• pp.111-118
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• 2017

The increased diversity of different types of energy sources requires moving towards smart distribution networks. This paper proposes a probabilistic DG (distributed generation) units planning model to determine technology type, capacity and location of DG units while simultaneously allocating ESS (energy storage systems) based on pre-determined capacities. This problem is studied in a wind integrated power system considering loads, prices and wind power generation uncertainties. A suitable method for DG unit planning will reduce costs and improve reliability concerns. Objective function is a cost function that minimizes DG investment and operational cost, purchased energy costs from upstream networks, the defined cost to reliability index, energy losses and the investment and degradation costs of ESS. Electrical load is a time variable and the model simulates a typical radial network successfully. The proposed model was solved using the DICOPT solver under GAMS optimization software.

• KCI Concrete Journal
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• 제14권3호
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• pp.93-101
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• 2002

The details of an approach to account for the factors that have been found to affect the ability and the probability to control cracking due to sawcutting in newly constructed concrete pavements are presented. Several factors such as material strength parameters, method and quality of curing, slab and subbase stiffness, and concrete shrinkage affect the probability of crack initiation. Others are relevant to concrete mixture characteristics that affect development of early aged stresses caused by shrinkage and thermally induced contraction. This paper presents the results of a probabilistic analysis of the factors that affect crack control using sawcut notches. Cost analyses on both conventional and early-entry sawcutting methods are shown to support the results of the probabilistic analysis. From both an operational and cost standpoint, it is evident for the environmental conditions considered that early-entry sawcut methodology holds a significant advantage over conventional methods.

• 조명전기설비학회논문지
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• 제25권1호
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• pp.59-63
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• 2011

In small-power applications, variable-speed motors having high efficiency and controllability become more dominant than brushed DC motors. BLDC motors with permanent magnets in the rotor and SRMs directed by reluctance torque due to no permanent magnets have been strongly studied as a candidate. Compared to the BLDC motors, SRMs are more suitable for low-cost applications since the magnetic structure is simple, mechanically robust, and cheap due to no additional excitation in the rotor such as copper wire, aluminum, and permanent magnets. In addition, relatively small number of phases in single and two-phase SRMs allows more cost savings with regards to material in the motor and switching devices in the converter. In this paper, several 2 phase SRMs are compared to a 3 phase 6/4 SRM in terms of flux distribution in key parts of the motors.

• Structural Engineering and Mechanics
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• 제47권2호
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• pp.287-305
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• 2013

Economic performances of consecutive multi-span suspension bridges are studied. The material amount and cost estimation formulas of the bridges have been derived in the part 1 of the study. A parametric study is carried out based on the formulas for investigating the different factors' effect on the bridge cost. The factors include the bridge sag, the bridge span, the bridge foundation and the environment condition, etc. Then, an economical layout of the bridges is proposed for different conditions. Lastly, a selection of suspension bridge types is discussed based on the economy of bridges.

• 전자공학회논문지D
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• 제34D권2호
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• pp.21-26
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• 1997

The dielectric effects on the parasitics of bondwires buried in slightly-lossy dielectric materials hav been investigated over a wide frequency range using the method of moments with incorporation of ohmic and dielectric losses. The FR-4 composite is widely used as a basis material for PCB and plastic packages, because of it sinherent electricl and chemical stbility and low cost. The cole-cole model, which is representative complex permittivity model of epoxy polymers, has been applied to consider the dielectric effects in the MoM calculation. The prasitic impedance of a grounded bondwire in FR-4 composite is greatly increased due to the dielectric loading effect enhanced by the radiation at high frequencies. These calculation results will be helpful for designing and packaging of high-frequency low-cost IC's.