• 대한토목학회논문집
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• 제11권3호
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• pp.59-65
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• 1991

본 연구에서는 국내 고속도로의 표준단면들을 포함한 포장구조 해석모델을 사용하여 아스팔트 콘크리트 포장체의 피로파괴 기준식을 개발하였다. 해석 대상 모델은 쇄석 및 아스팔트 안정처리 기층을 갖는 2430개의 4충 포장구조로 하였으며, 각 모델의 물성을 공용성 한계를 PSI=2.5로 한 AASHTO 설계식과 다층 탄성해석 프로그램인 SINELA에 적용, 포장체의 통과예상 교통량과 아스팔트 콘크리트층 하단에서의 최대 인장 변형률과의 관계를 회귀분석하였다. 분석 결과로부터, 신뢰도 50%와 95% 수준의 파괴기준식을 제안하였다. 타 연구결과와 비교한 결과 신뢰도 95% 수준의 파괴기준식은 균열의 발생을 공용성 한계로 보는 기존의 피로 파괴기준식과 같은 정도의 교통량을 추정하고 있음을 알 수 있었다. 또한 신뢰도 수준에 따른 파괴기준식을 신뢰도 50%, 수준의 파괴기준식으로부터 간접 추정할 수 있는 관계식을 제안하였다.

• 한국농촌건축학회논문집
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• 제18권1호
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• pp.19-28
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• 2016

This research aimed to suggest a standard design that reflects Hanok design tendency, and present a selective design that can fulfill a building owner's intention beyond the simple function of building permit or report. In addition, this research attempted to become a standard by establishing a criterion in calculating the measurements of section design or primary framework members, in order to be a guideline for designing Hanok in different sizes and forms. The results are as follows. The building area of Hanok standard design was set to be below $85m^2$, with a straight type of $83.16m^2$ and an L-shape of $84.24m^2$. By dividing the plane into a straight type and L-shape, two straight types were suggested: 'general type' and 'large living room type.' The upper floor space, along with the main room and small room, was proposed as an option to be changed into a room where an underfloor heating is installed depending on the building owner's intention. In addition, a criterion for side design and calculation of framework measurements was suggested and applied, while a five-girder design without high pillars was suggested for material-assembling structure. Two types of pillars-circumference and square cylinder-were proposed for the building owner to choose from, and a pointed beam house and ikgong(orthogonally-projected bracket) house were suggested for pojak bracket structure so either of them could be chosen according to the building owner's taste and economic condition. Finally, the sectional size of main materials were divided according to the form of pojak bracket structure to be proposed.

• Structural Engineering and Mechanics
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• 제41권4호
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• pp.495-508
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• 2012

The strength theory of concrete is significant to structure design and nonlinear finite element analysis of concrete structures because concrete utilized in engineering is usually subject to the action of multi-axial stress. Experimental results have revealed that lightweight aggregate (LWA) concrete exhibits plastic flow plateau under high compressive stress and most of the lightweight aggregates are crushed at this stage. For the purpose of safety, therefore, in the practical application the strength of LWA concrete at the plastic flow plateau stage should be regarded as the ultimate strength under multi-axial compressive stress state. With consideration of the strength criterion, the ultimate strength surface of LWA concrete under multi-axial stress intersects with the hydrostatic stress axis at two different points, which is completely different from that of the normal weight concrete as that the ultimate strength surface is open-ended. As a result, the strength criteria aimed at normal weight concrete do not fit LWA concrete. In the present paper, a multi-axial strength criterion for LWA concrete is proposed based on the Unified Twin-Shear Strength (UTSS) theory developed by Prof Yu (Yu et al. 1992), which takes into account the above strength characteristics of LWA under high compressive stress level. In this strength criterion model, the tensile and compressive meridians as well as the ultimate strength envelopes in deviatoric plane under different hydrostatic stress are established just in terms of a few characteristic stress states, i.e., the uniaxial tensile strength $f_t$, the uniaxial compressive strength $f_c$, and the equibiaxial compressive $f_{bc}$. The developed model was confirmed to agree well with experimental data under different stress ratios of LWA concrete.

• 한국생활과학회지
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• 제10권1호
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• pp.83-91
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• 2001

Currently, obtaining information about the housing studies through the internet web sites is one of the outstanding mediums. Those are of the housings, architecture, interior design, furniture products, hotels and its journals, etc., and out of all those informations are the highly expected value of use. But. it may causes the public users to experience a negative effect, because many of those informations provided on the internet web sites related to the housing studies/informations are not providing an equal quality of information. And measuring the quality is also not easy. This study focuses on the establishment of evaluation criterion for the housing information-related internet web sites. In such a vein, it proposes a clear model to evaluate the information qualities with the 43 questionnaires / examining items. To test the questionnaires/rating items, the analysis has been implemented which has shown the reciprocal effect between the 2 major factors. One major factor with 4 variables on the information searches are (1) the accuracy/reliability of contents and techniques, (2) the design of a picture and communication, (3) the readability and security, and (4) the security of private information, and the other factor with 3variables on the additional services are (1) the diversities of contents and ease of orderings, (2) the abilities of search and e-mail, and (3) the events and after services. This study/rating model will provide the users with a fundamental material in evaluating the quality of housing information on the internet web sites.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권2호
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• pp.117-126
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• 1999

The environmental impact of the KEPCO 765-kV transmission line was studied using a full scale test line in order to develop the design technology. Therefore this paper describes an environmental design summary of the audible noise, hum noise, wind noise, radio interference, TV interference and electric field measurement from the KEPRI 765-kV double circuit transmission test line with a bundle of $6-480mm^2$ conductors per phase. The analysis of the test results shows that 6-Rail and 6-Cardinal conductors bundle satisfy the audible noise criterion & TV interference under the stable rainy weather condition and the radio interference level under the fair weather. And the other items are also agreed with the design level criterion for KEPCO 765-kV transmission line.

• Corrosion Science and Technology
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• 제16권5호
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• pp.235-240
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• 2017

Regional cathodic protection has significant impact on pipeline integrity management. After risk analyses of a newly built gas distribution station constructed in an area with large dwelling density, risk score was high because of potential threat caused by galvanic corrosion. Except reinforced steel in concrete, there are four kinds of metal buried under earth: carbon steel, galvanized flat steel, zinc rod and graphite module. To protect buried pipeline from external corrosion, design and construction of regional cathodic protection was proposed. Current density was measured with potential using potential dynamic test and boundary element method (BEM) was used to calculate current requirement and optimize best anode placement during design. From our calculation on the potential, optimized conditions for this area were that an applied current was 3A and anode was placed at 40 meters deep from the soil surface. It results in potential range between $-1.128V_{CSE}$ and $-0.863V_{CSE}$, meeting the $-0.85V_{CSE}$ criterion and the $-1.2V_{CSE}$ criterion that no potential was more negative than $-1.2V_{CSE}$ to cause hydrogen evolution at defects in coating of the pipeline.

• 한국조경학회지
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• 제28권5호
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• pp.93-103
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• 2000

This research is to propose a rational criterion of the selection and the management f the roadside trees, and to establish the planting design and system with the objective of improving the roadside environment. All of the roadside trees in each objective courses in Kangnung, and the soil disposition, hardness of the soil in the planting areas have been investigated. Also, we have surveyed the kinds of the trees which kandgnung inhabitants want. The conclusion is as follows Most of roadsides have trees, but they need the introduction of shrubs or ground covering plants according to the locations and the environmental conditions. We have selected nineteen species in regard to the roadside tree criterion and the growing conditions living in Kangnung. It is desirable that we make banding style planting space between each roadside tree to improve the low ratio of green coverage. We have found out that Ligustrum obtusifolium, Buxus micropnylla, Euonymus japonica, Rhododendron schlippenbachii, Phyllostachys nigro and Rosa rugosa, ect. are suitable. In order to soften and weaken the rigidity of the hard substances on a paved roadside, the climbers such as the perennial herbaceous flowering and hedera rhombea should be preferred rather than annual herbaceous flowering because of curtailment of expenditure. To posses a systematical greenery frame in kangnung, we have planned a planting design system that would expand the greenery space every year. Moreover, we have to make a plan to overcome space restrictions. We have established a flexible plan considering the roadside conditions and the improved standard planting methods with an ultimate aim to create a special roadside view.

• 소성∙가공
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• 제23권4호
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• pp.238-243
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• 2014

Recently, magnesium alloys have been widely used in the automotive, aerospace and electronics industries with the advantages of high specific strength, excellent machinability, high electrical conductivity, and high thermal conductivity. Deep drawn magnesium alloys not only meet the demands environmentally and the need for lighter products, but also can lead to remarkably improved productivity and more rapid qualification of the product The current study reports on a failure prediction procedure using finite element modeling (FEM) and a ductile fracture criterion and applies this procedure to the design of a deep drawing process. Critical damage values were determined from a series of uniaxial tensile tests and FEM simulations. They were then expressed as a function of strain rate and temperature. Based on the plastic deformation histories obtained from the FEM analyses of the warm drawing process and the critical damage value curves, the initiation time and location of fracture were predicted. The proposed method was applied to the process design for fabrication of a Mg automotive compressor case and verified with experimental results. The final results indicate that a Mg case part 39% lighter than an Al die casting part can be produced without any defects.

• 대한인간공학회지
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• 제29권6호
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• pp.843-851
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• 2010

This study aims to systematically develop a usability evaluation model using the Structural Equation Model (SEM) from experiment of usability on using vehicle. Vehicle developers have been adding many functions for enhance the user satisfaction. But it will be made the trade-off problem of usability and design elements of vehicle interior from attempt to make best usability satisfaction in a restricted space. To solve the trade-off problem, we set a new solution criterion from usability evaluation model. The usability experiment is based on major activity pool from derived user's acts pattern in vehicle for make more accurate usability evaluation model. And this model was built with twenty-nine measurement variables for the evaluation of usability of vehicle user. As a result, the proposed SEM model showed statistical significance as well as a high level of R Square (0.7144). This model shows the relationships of detailed usability and design elements. According to the result, this study introduces the criterion to secure the best satisfaction of usability and design elements.

• 한국초전도ㆍ저온공학회논문지
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• 제20권2호
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• pp.34-39
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• 2018

A cryogenic cooling system is designed for a 154 kV/ 2 kA three-phase hybrid type superconducting fault current limiter (SFCL). The superconducting modules of the SFCL have the operating condition of 71 K at 500 kPa. The total heat load of the SFCL including the cooling system is estimated at 9.6 kW. The cooling system of the closed loop is configured to meet the operating condition, depending on cooling methods of forced flow cooling and re-liquefaction cooling. The cooling system is composed of three cryostats with superconducting modules, cryocoolers, liquid nitrogen circulation pumps, a subcooler and a pressure builder. The basic cooling concept is to circulate liquid nitrogen between three SFCL cryostats and the cryocooler, while maintaining the operating pressure. The design criterion for the cooling system is based on the operation results of the cooling system for a 154 kV/2 kA single-phase hybrid SFCL. The specifications of system components including the piping system are determined according to the design criterion.