• 국제초고층학회논문집
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• 제1권4호
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• pp.311-332
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• 2012

Earthquake response of mid-rise to high-rise buildings provided with friction dampers is investigated. The steel buildings are modelled as shear-type structures and the investigation involved modelling of the structures of varying heights ranging from five storeys to twenty storeys, in steps of five storeys, subjected to real earthquake ground motions. Three basic types of structures considered in the study are: moment resisting frame (MRF), braced frame (BF), and friction damper frame (FDF). Mathematical modelling of the friction dampers involved simulation of the two distinct phases namely, the stick phase and the slip phase. Dynamic time history analyses are carried out to study the variation of the top floor acceleration, top floor displacement, storey shear, and base-shear. Further, energy plots are obtained to investigate the energy dissipation by the friction dampers. It is seen that substantial earthquake response reduction is achieved with the provision of the friction dampers in the mid-rise and high-rise buildings. The provision of the friction dampers always reduces the base-shear. It is also seen from the fast Fourier transform (FFT) of the top floor acceleration that there is substantial reduction in the peak response; however, the higher frequency content in the response has increased. For the structures considered, the top floor displacements are lesser in the FDF than in the MRF; however, the top floor displacements are marginally larger in the FDF than in the BF.

• 한국염색가공학회지
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• 제23권2호
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• pp.107-117
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• 2011

Polyurethane (PU) was synthesized by one-shot process and the PU nanofiber was prepared by electrospinning. In this study, electrospun PU multi-membranes were prepared with various coating thickness ratio of base resin to top resin, where the base resin contains melamine curing agent and acid catalyst and the top resin contains water-repellent agent of fluoro-carbon compounds. The PU nanofiber multi-membranes were analyzed by field-emission scanning electron microscopy, differential scanning calorimeter, breathability, tensile strenth, air permeability and water resistance. The results showed that the PU multi-membrane provided excellent waterproof and moisture permeability.

• 품질경영학회지
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• 제37권3호
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• pp.1-9
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• 2009

Top Managers are apt to do the decision making on the base of cost-benefit analysis. Therefore the return on quality is indispensable to get the commitment of the top managers on the quality programs. The monetary or tangible effects of the most improvement activities through the suggestion systems and the quality circle activities are computed and reported. In most cases the reported gains are much bigger than the input invested. In spite of the reported high return many top managers are doubtful about the truth of reports because the gains are not translated into the profit on the income statement. This paper discusses about the mechanism of individual improvement activities and analyze the system effect which sum the individual effect and the realization effect on the income statement during that period. This will help the top managers to commit on the quality programs with high confidence.

• 한국응용과학기술학회지
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• 제24권4호
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• pp.399-409
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• 2007

Characteristics of polyaniline anti-corrosive coatings with various primer coating resins(epoxy resin, urethane resin, and others) and top coating resins(epoxy and acrylic urethane resins) were investigated through adhesion, acid resistance, alkaline resistance, water resistance, and anti-corrosion tests. As a result, the anti-corrosive properties of the prepared coatings using polyaniline varied with the types of primer and top coating resins. In this condition, the properties of adhesion, chemical resistance, and water resistance were found to be very satisfactory when using emeraldine base (EB) of polyaniline blended with single-packaged urethane and acrylic urethane resins as the primer coatings, and using acrylic urethane resin as the top coatings. Also, the anti-corrosive function of these anti-corrosive coatings was well preserved for 1000 hr in the salt spray experiment.

• 한국공간구조학회논문집
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• 제10권3호
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• pp.49-56
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• 2010

본 연구에서는 스마트 최상층 면진시스템을 적용한 고층건물의 풍응답 제어성능을 검토해보았다. 이를 위하여 77층 초고층 건물을 예제구조물로 선택하였고 풍동실험을 통해서 얻은 풍하중을 사용하여 수치해석을 수행하였다. 예제구조물의 최상층은 FPS 및 MR 감쇠기로 구성된 스마트 면진시스템을 이용하여 주구조물과 분리된다. 주구조물의 동적응답을 저감시키는 것이 스마트 최상층 면진시스템의 가장 중요한 목표이지만 면진된 최상층의 과도한 응답은 구조물을 불안정하게 만들 수 있다. 따라서, 본 연구에서는 면진된 최상층과 주구조물을 효과적으로 제어하기 위하여 스카이훅제어기를 제어알고리즘으로 사용하였다. 제안된 스마트 최상층 면진시스템의 제어성능을 검토하기 위하여 일반적인 수동 최상층 면진시스템의 제어성능과 비교하였다. 수치해석결과 제안된 스마트 최상층 면진시스템을 이용하면 일반적인 수동 최상층 면진시스템에 비해서 면진층의 변위를 효과적으로 줄이면서도 구조물의 응답을 저감시킬 수 있음을 확인할 수 있었다.

• 한국정보과학회논문지:데이타베이스
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• 제36권3호
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• pp.189-197
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• 2009

Top-k 질의는 많은 센서 네트워크 응용 분야에서 중요하게 사용된다. 기존에 제안된 필터 기반의 Top-k 질의 처리 기법은 질의 결과에 영향을 미치는 값만을 수신하기 위해 각 센서 노드의 측정 허용 범위를 필터로 설정함으로써 센서 데이타의 전송 횟수를 줄인다. 하지만, 센서 데이타의 재검증과 필터의 재배포 과정에서 추가적인 에너지를 소모한다. 또한, 질의 결과값이 빈번히 변경될수록 필터의 재배포 횟수가 증가하여 에너지의 소모가 더욱 증가한다. 본 논문에서는 Top-k 질의를 처리하기 위해서 측정한 데이타를 기반으로 우선 순위를 결정하고, 우선 순위에 따라 최소한의 센서 데이타를 수집하는 새로운 Top-k 질의 처리 기법을 제안한다. 제안하는 기법의 우수성을 보이기 위해서 시뮬레이션을 통한 성능 평가를 수행하였으며, 그 결과 기존 필터 기반의 기법에 비해 네트워크의 수명이 크게 향상되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권6호
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• pp.2111-2131
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• 2015

Tiered wireless sensor network is a network model of flexibility and robustness, which consists of the traditional resource-limited sensor nodes and the resource-abundant storage nodes. In such architecture, collected data from the sensor nodes are periodically submitted to the nearby storage nodes for archive purpose. When a query is requested, storage nodes also process the query and return qualified data as the result to the base station. The role of the storage nodes leads to an attack prone situation and leaves them more vulnerable in a hostile environment. If any of them is compromised, fake data may be injected into and/or qualified data may be discarded. And the base station would receive incorrect answers incurring malfunction to applications. In this paper, an efficient verifiable top-k query processing scheme called EVTQ is proposed, which is capable of verifying the authentication and completeness of the results. Collected data items with the embedded information of ordering and adjacent relationship through a hashed message authentication coding function, which serves as a validation code, are submitted from the sensor nodes to the storage nodes. Any injected or incomplete data in the returned result from a corresponded storage node is detected by the validation code at the base station. For saving communication cost, two optimized solutions that fuse and compress validation codes are presented. Experiments on communication cost show the proposed method is more efficiency than previous works.

• 한국해안·해양공학회논문집
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• 제22권1호
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• pp.1-9
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• 2010

말뚝 상부에서 수평력 대부분을 저항한다는 매커니즘을 활용하여, 횡방향 하중이 대부분인 항만 및 해양구조물에 효율적으로 적용할 수 있는 새로운 말뚝 형식을 고안하였다. 이번 연구에서는 버켓 기초식 보강기법, 팽이 기초식 보강기법, 그라우팅식 보강기법 등 3가지 형태의 보강기법을 활용한 상부 확대형 횡방향 지지 증대 말뚝에 대한 3차원 유한요소해석을 수행하였다. 이를 통해 지반의 종류를 비롯하여, 각 보강 기법의 종류, 말뚝의 종류 및 길이, 지반의 심도 등 다양한 변수가 말뚝의 횡방향 지지 거동에 미치는 영향을 검토하였다. 해석 결과, 버켓 기초를 활용한 경우 팽이기초나 그라우팅 기법 등 전반적으로 다른 보강기법을 활용한 경우에 비해 횡방향 지지력 효율이 상대적으로 가장 뛰어난 것으로 나타난다.

• 한국지반공학회논문집
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• 제24권10호
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• pp.121-129
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• 2008

본 논문에서는 기존 공장제작 콘크리트 팽이기초가 갖는 문제점들을 해결 보완하기 위해 개발된 현장타설 팽이기초의 거동특성을 검토하고자, 현장재하시험 결과를 근거로 팽이기초의 수치해석 모델링을 하였으며, 구성된 수치해석 모델을 이용하여 기초형식 및 형상 변화에 따른 거동특성을 비교 분석하였다. 수치해석 결과, 현장타설 팽이기초 (In-situ TBF)는 전단활동파괴면이 더 깊고 넓게 형성되어 지반파괴에 대한 저항력이 증가하게 되고, 이로 인해 지지력이 향상되는 것을 확인 할 수 있었다. 기초의 형상에 따른 효과는 원추부에 의한 것 보다는 말뚝부에 의한 효과가 더 큰 것으로 나타났으며, 원추부와 말뚝부가 조합되어 이루어진 팽이기초 형상이 가장 큰 효과를 나타내는 것으로 나타났다. 말뚝부의 길이를 증가시키면서 해석을 수행한 결과, 현재 사용되고 있는 팽이기초말뚝부의 길이가 효율적 크기라는 것을 확인 할 수 있었다.

• Geomechanics and Engineering
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• 제7권1호
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• pp.87-103
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• 2014

This study investigated the effect of soil-structure interaction (SSI) on the response of base-isolated buildings. Seismic isolation can significantly reduce the induced seismic loads on a relatively stiff building by introducing flexibility at its base and avoiding resonance with the predominant frequencies of common earthquakes. To provide a better understanding of the movement behavior of multi-story structures during earthquakes, this study analyzed the dynamic behavior of multi-story structures with high damping rubber bearing (HDRB) behavior base isolation systems that were built on soft soil. Various models were developed, both with and without consideration of SSI. Both the superstructure and soil were modeled linearly, but HDRB was modeled non-linearly. The behavior of the specified models under dynamic loads was analyzed using SAP2000 computer software. Erzincan, Marmara and Duzce Earthquakes were chosen as the ground motions. Following the analysis, the displacements, base shear forces, top story accelerations, base level accelerations, periods and maximum internal forces were compared in isolated and fixed-base structures with and without SSI. The results indicate that soil-structure interaction is an important factor (in terms of earthquakes) to consider in the selection of an appropriate isolator for base-isolated structures on soft soils.