• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.43-47
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• 2004

Most of LV customer has been composed the 3-phase four wire system distribution system which is supplying simultaneously at the 1-phase & 3-phase load. In this system, the composition of the power apparatus system is simple rather than conventional separation mode of the 1-phase & 3-phase, But due to uneven load unbalance or unclean power quality, various kinds such as do-rating or power losses become an issue. In this paper, we measured and analyzed voltage and current waveform in the field, compared with internationally allowable voltage unbalance limits.

• 대한전기학회논문지
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• 제31권7호
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• pp.11-17
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• 1982

In this paper, a reliable and convenient evaluation method for the adequacy of any radial distribution line's voltage drop is proposed for improvement of the voltage regulation of the distribution line under operation. Using the voltage measurement of the first load branch point and the last point on the given distribution line its average line voltage drop and the line voltage drop variance by pure load variation are computed. And by these values and allowable or required line drop from proper voltage regulation view point, present adequency index and operation improvement index of the line drop are newly introduced for the evaluation of the given distribution line's voltage regulation. As a result of application to the 4 cases of study, the proposed method is proved to be reliable and convenient.

• 한국건축시공학회지
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• 제6권4호
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• pp.45-52
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• 2006

Top Down method is more widely used in downtown construction, recently. As underground construction constitutes a significant portion of the total construction cost and time in Top Down construction, it is important to develop a construction method to reduce the time required in underground works. The purpose of this study is to analyze load carrying capacity of Top Down prefounded columns on different excavation schedule. When several floors are excavated, the valid buckling length of prefounded column is increased and allowable buckling stress is decreased. The result shows that all columns are safe in buckling down to B3 story whether 2 or 3 stories are excavated. However, several columns are not safe from B4 story when 2 or 3 stories are excavated straightly. With these results, a process can be designed that the first three stories in the basement are excavated, and then excavate B4 story after placing concrete on B1 and B2 floor.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.333-336
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• 2008

U-Channel Bridge is effective bridge type, because its edge beam performs role of barrier and enables to reduce additional dead loads. Nevertheless, there is possibility of bridge collapse under impact load due to car crash. Also, edge beam must have ability to induce safe driving and prevent falling accidents. Therefore, this study carries out analysis of behavior of edge beam and slab and evaluation of structural stability under impact loads, based on Korean Highway Bridge Design Specifications and AASHTO LRFD Bridge Design Specification. According to analysis result, the maximum stress of edge beam and slab satisfies specification of allowable stress.

• 한국안전학회지
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• 제6권3호
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• pp.56-63
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• 1991

본 연구는 가설부재의 신뢰성 설계규준을 고찰하고, Ellingwood가 제안한 신뢰성 해석과 신뢰성 설계규준 산정 알고리즘으로 부터 실용적인 알고리즘을 유도하였다. 하중의 불확실량은 우리의 실정을 고려한 적절한 값을 택하여 신뢰성 해석 및 신뢰성 설계규준을 산정했다. 현행 WSD와 USD 설계법의 신뢰성 수준을 분석함으로써, 우리 실정에 적당한 목표신뢰성지수 $\beta$$_{o}$ =3.5를 택하여 LRFD설계규준에 의한 하중-저항계수를 제안했으며, 신뢰성 설계와 비슷한 신뢰성을 갖는 WSD의 강재의 허용응력을 산정제안했다. 본 연구에서 제안한 신뢰성 설계규준 및 허용응력은 일정한 신뢰성을 주는 보다 합리적인 설계가 됨을 알 수 있었다.

• 한국강구조학회 논문집
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• 제12권3호통권46호
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• pp.251-258
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• 2000

강구조물과 부재들의 지진 손상도 평가법에 새롭게 접근하기 위하여 강한 지진하중을 받는 강재 교각에 대해 수치해석을 수행하였다. 새로운 손상도 평가법에서 파괴 상태에 대한 기준은 지진하중이 재하되는 동안에 응력집중이 가장 심한 단면의 한 부분에서 누적소성변형율의 값이 90%에 이르게 되는 때를 의미한다. 단주기 특성의 지진하중에 대해서는 소성변형율의 누적에 의한 국부좌굴 파괴보다는 허용변위를 초과하는 전체좌굴에 의한 파괴가 지배적인 것으로 밝혀졌다. 장주기 특성의 지진하중에 대해서는 소성변형율이 강재교각 하부의 모서리 부분 요소에 누적되면서 누적 소성변형율에 의한 국부좌굴로 파괴되는 결과를 보였다.

• 한국통신학회논문지
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• 제28권1C호
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• pp.72-80
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• 2003

본 논문은 멀티패스 페이딩이 존재하는 CDMA 채널에서 새로운 빔형성 알고리즘을 통해 적응 배열 안테나의 성능을 향상시키기 위한 최적의 웨이트 벡터를 구하는 방법을 제시하였다. 제안한 빔형성 알고리즘은 멱승법을 근간으로 하며, 전체 계산량이 O(4N)밖에 되지 않는 선형화 된 멱승법(power method) 알고리즘이다. 여기서 N은 안테나 수를 의미한다. 제안된 알고리즘의 성능은 IS-2000 1X CDMA 환경에서 심볼 에러율(symbol error rate), 사용 가능자수(allowable capacity), 수렴도(convergence) 등에 대한 분석을 통해 확인하였다. 성능분석 결과 적응 배열 안테나 시스템은 기지국 셀 내에서 기존 안테나 시스템에 비해 6-10배정도 사용 가능자수가 증가하였다. 또한, 제안 알고리즘은 심볼 에러율, 수렴도, 계산량의 모든 경우에서 기존 알고리즘에 비해 우수한 성능을 보임을 확인하였다.

• Journal of the Korean Wood Science and Technology
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• 제13권4호
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• pp.67-72
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• 1985

To improve the bending strength of sawdustboard, verious resin contents of 10, 13, 16, and 19% were applied to the thin shell (face layer) composed with wire net or not. The shell effect of sawdust and wire net composition formed with core sawdustboard were evaluated. Forcusing on the effects of wire net composition and noncomposition including a comparison with chipboard and veneer complyboard, bending properties (Modulus of rupture (MOR), Modulus of elasticity (MOE), Stress at proportional limit ($S_{pl}$). Work to maximum load ($W_{ml}$))were analyzed and discussed. 1. In modulus of rutpute, veneer comply was the highest (621.5 kg/$cm^2$), and next decreasing order was wire net composition (159.1 kg/$cm^2$), chipboard (81.75 kg/$cm^2$), and wire net noncomposition (76.21 kg/$cm^2$) as in modulus of elasticity, work to maximum load, except for stress at proportional limit. 2. The highly significant effects were shown in both wire net composition and noncomposition, at the same time wire net composition exceeded two times of noncomposition throughout resin contents in bending properties. Chipboard was similar to the mean or 16% resin content in noncomposirion. 3. Every board in wire net composition above 10% resin content was beyond 100 kg/$cm^2$ in MOR, minimum allowable strength for structural use according to KS F 3104. In conclusion, the feasibility for improving the bending strength of weak sawdustboard by wire net composed shell was offered.

• Journal of Advanced Marine Engineering and Technology
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• 제40권9호
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• pp.780-785
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• 2016

선박의 연료로 이용되는 중유는 지구 온난화를 일으키는 유해가스를 배출한다. 이를 저감하기 위해 친환경선박으로 표현되고 있는 녹색선박이 등장하게 되었고, 천연가스를 연료로 하는 액화천연가스(LNG) 연료 선박이 대표적인 사례이다. 본 논문에서는 LNG 선박에 사용되는 극저온 환경에서 고압 하중을 받는 기화기와 출입구 배관의 구조 건전성을 ASME 코드에 따라 평가하고 실용화한 최초의 사례이다. 기화기와 배관은 유한요소법을 사용하여 구조해석을 수행하였다. 기화기는 등가응력을 바탕으로 ASME Section VIII Division 2에 제시된 허용응력과 비교하여 건전성 평가를 수행하였고, 배관은 성분별 응력을 조합하여 ASME B31.3에 제시된 허용응력과 비교 및 건전성 평가를 수행하였다. 각 하중에 대한 구조물들의 응력 결과는 허용응력 범위 이내에 있으므로 구조적 건전성을 유지하는 것으로 평가되었다.

• 한국도로학회논문집
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• 제15권1호
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• pp.23-36
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• 2013

PURPOSES: The problem under this circumstance is that the erosion not only drops strength of the steel dowel bar but also comes with volume expansion of the steel dowel bar which can reduce load transferring efficiency of the steel dowel bar. To avoid this erosion problem, alternative dowers bars are developed. METHODS: In this study, the bearing stresses between the FRP tube dowel bar and concrete slab are calculated and compared with its allowable bearing stress to check its structural stability in the concrete pavement. These comparisons are conducted with several cross-sections of FRP tube dowel bars. Comprehensive laboratory tests including the shear load-deflection test on a full-scale specimen and the full-scale accelerated joint concrete pavement test are conducted and the results were compared with those from the steel dowel bar. RESULTS: In all cross-sections of FRP tube dowel bars, computed bearing stresses between the FRP tube dowel bar and concrete slab are less than their allowable stress levels. The pultrusion FRP-tube dowel bar show better performance on direct shear tests on full-scale specimen and static compression tests at full-scale concrete pavement joints than prepreg and filament-winding FRP-tube dowel bar. CONCLUSIONS: The FRP tube dowel bars as alternative dowel bar are invulnerable to erosion that may be caused by moisture from masonry joint or bottom of the pavement system. Also, the pultrusion FRP-tube dowel bar performed very well on the laboratory evaluation.