• 한국전자통신학회논문지
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• 제6권4호
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• pp.473-478
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• 2011

본 논문은 유한 접지 도체판 위의 시험장에 대해서 접지 도체판의 edge가 NSA(Normalized Site Attenuation)에 미치는 영향에 대해서 검토하였다. 사용하는 안테나를 광대역 미소다이폴안테나로 가정하여 방사성 방해파의 측정시설로 사용하는 시험장의 크기가 방해파의 측정환경으로 적합한지를 평가하기 위한 기준이 되는 NSA의 이론치를 GTD(Geometric theory of diffraction)법을 적용하여 계산하였다. 본 논문에서는 유한 접지 도체판 위의 송 수신 안테나가 상호 영향을 받지 않을 경우, 접지 도체판의 크기가 NSA에 미치는 영향을 수평편파와 수직편파에 대해서 측정거리 3 m법을 이용하여 고찰 하였다. 수치적으로 검토한 결과, 수평편파에서는 일반적인 규격에서 규정하고 있는 타원평면의 규격 정도의 접지 도체판에서도 edge의 영향을 무시 할 수 있으나, 수직편파의 경우에는 edge의 영향을 1 dB 이하로 줄이기 위해서는 유한 도체 접지판의 크기를 크게 가져가야 한다는 것을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제26권3호
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• pp.344-352
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• 2002

In the analysis of the 3 dimensional plate structures by the finite element method, the triangular elements are generally used for the global stiffness matrix of the analyzed system. But the triangular elements of the plates have some problems in the process of formulation and in the precision of analysis. The formulation of the finite element method to analyze 3 dimensional plate structures using quadrilateral elements is presented in this paper. The degree of freedom off nodal point is 6, that is, the displacements in the direction off-y-z is and the rotations about x-y-z axis and then the degree of freedom off element is 24. For the comparison of the analysis using triangular elements and quadrilateral elements, the rectangular plates subjected to the uniform load and a concentrated load on the centroid of the plate, for which the theoretical solutions have been obtained, are analyzed. The calculated deflections of the rectangular plates using the finite element method by the triangular elements and the quadrilateral elements are also compared with the deflections of the plates calculated by theoretical solutions. The defections of the rectangular plates calculated by the finite element method using the quadrilateral elements are closer to the theoretical solutions than the defections calculated by the finite element method using the triangular elements. The deflection of the centroid of plate, calculated by the finite element method, converges to that of theoretical solution as the number of elements is increased. This convergence is much more rapid for the case of using the quakrilateral elements than fir the case of using triangular elements.

• Journal of Mechanical Science and Technology
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• 제20권5호
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• pp.710-716
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• 2006

Micro-PIV system with a high speed CCD camera is used to measure the flow field near the advancing meniscus of a water slug in microchannels. Image shifting technique combined with meniscus detecting technique is proposed to measure the relative velocity of the liquid near the meniscus in a moving reference frame. The proposed method is applied to an advancing front of a slug in microchannels with rectangular cross section. In the case of hydrophilic channel, strong flow from the center to the side wall along the meniscus occurs, while in the case of the hydrophobic channel, the fluid flows in the opposite direction. Further, the velocity near the side wall is higher than the center region velocity, exhibiting the characteristics of a strong shear-driven flow. This phenomenon is explained to be due to the existence of small gaps between the slug and the channel wall at each capillary corner so that the gas flows through the gaps inducing high shear on the slug surface. Simulation of the shape of a static droplet inside a cubic cell obtained by using the Surface Evolver program is supportive of the existence of the gap at the rectangular capillary corners. The flow fields in the circular capillary, in which no such gap exists, are also measured. The results show that a similar flow pattern to that of the hydrophilic rectangular capillary (i.e., center-to-wall flow) is always exhibited regardless of the wettability of the channel wall, which is also indicative of the validity of the above-mentioned assertion.

• 대한건축학회논문집:계획계
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• 제34권11호
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• pp.95-104
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• 2018

Healthcare technology has been growing and fostering cooperation between industry, university and hospitals as growth engines in korea. So, the medibio research institutes in hospital have been constructed to promote research and industrialization centering on healthcare technology. The purpose of this study is to investigate the cases of research institutes in hospitals, and search the characteristics of building organization of medibio research laboratory facilities. Case study is investigated by floor plan, homepage and site visits about five research institutes selected in research-driven hospitals. The facility title and size of research laboratory is originated from site area and research building location. The building function include not only the research lab and business office reflecting on the development platform, and but assembly and meeting room in the ground level. Laboratory floor plans have three types, rectangular, rectangular+linear and linear type, one is traditional and efficient, the others are people and friendly. And building core types are correlated with lab space unit modules, single and double side core are shown in rectangular type. All the laboratories are open lab, composed with laboratory bench and research note writing desk facing the lab service and enclosed lab-support area. And they have communication space looking as warm and cozy common area for the innovation, convergence and collaboration. As the high risk of contamination and high standard for safety and security, equipment and facilities are well managed with biological environment including BSC, fume hood, PCR classification, eye washing and emergency shower.

• 한국지반공학회논문집
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• 제24권4호
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• pp.23-36
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• 2008

본 연구는 측방변형을 일으키는 수평모래지반에 매설된 사각형 수동열말뚝의 모형실험에 대한 것이다. 말뚝의 형상, 열말뚝의 위치, 말뚝의 간격과 지반변형에 따른 열말뚝의 특성을 고찰하고자 하였다. 실험결과는 다음과 같다. 수평응력의 분포양상은 말뚝의 형상과 위치에 따라 삼각형, 사다리꼴, 사각형의 형태로 다양하게 나타났다. 휨모멘트는 B-type의 경우 outer pile이 inner pile보다 크게 나타났으나, H-type의 경우는 inner pile이 outer pile 보다 크게 나타났다. 수평저항력비$(R_f)$는 말뚝의 형상에 관계없이 열말뚝의 수평간격이 증가함에 따라 증가하는 경향으로 나타났다. 수평저항력의 작용점위치(Y/L)는 지반변위와 수평간격에 따라 큰 변화를 보이지 않으며, H-type이 B-type보다 조금 크게 나타났다.

• 한국항해학회지
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• 제8권2호
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• pp.43-50
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• 1984

When the static load is applied to the ship's hull the deflection due to the bending moment from longitudinal direction has not been considered in the usual calculation of maximum bending moment. In fact, however, the deflection of ship's hull must be affected by the above-stated bending moment, and in this case the value of the maximum bending moment would be lessened in comparision with the result of usual calculation. In this paper, the author at first calculated the difference between the two values in case of rectangular barge, and suggested a practical criterion of longitudinal strength.

• 대한기계학회논문집
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• 제14권2호
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• pp.413-421
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• 1990

Acoustic emission signals due to leak from circular holes of 0.4, 1, 2 and 4mm diameter and rectangular slits of different geometry having the same cross section as 4mm diameter hole was studied both analytically and experimentally. Acoustic emission signals from a wide-band type transducer were transformed to digital signals through a digital oscilloscope, and $V_{rms}$ and frequency spectrum were obtained by processing digital signals. Relationships between acoustic parameters and fluid mechanical parameters were derived analytically. A quadrapole aerodynamic model was applied in the analysis of leak from the circular holes and $V_{rms}$ was found to be proportional to the root square of leak rate through the circular hole. A modified model based on dipole source mechanism and laminar equivalent diameter was applied in the analysis of leak signals from the rectangular slits. In the case of constant pressure, $V_{rms}$ increased as the laminar equivalent diameter of slit decreased. In the case of constant laminar equivalent diameter, however the result was similar to that for leak from the circular hole. The frequency spectra of leak signals shows the same frequency characteristics irrespective of the pressure difference.rence.

• 전자공학회논문지T
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• 제35T권1호
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• pp.75-81
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• 1998

본 논문은 장방형 다이아프램 형상과 단일형 피에조저항 전단응력 스트레인 게이지 와의 관계를 해석하여 최적의 전단응력 압력센서를 설계하기 위한 것이다. 다이아프램상의 전단응력을 시뮬레이션 하기 위하여 유한요소법 분석 프로그램 ANSYS 5.1를 사용하였다. 시뮬레이션 결과는 다이아프램 형상비가 3일때 스트레인 게이지의 위치는 중앙에서, 크기는 전체 장방형 다이아프램 크기의 8%를 점유할때 온도에 안정적이고, 최대 감도를 가진다는 것을 조사하였다.

• 한국농공학회지
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• 제34권E호
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• pp.30-44
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• 1992

A modification of the TEACH-like computer program based on the k-$\varepsilon$ turbulence transport was applied for predicting air mixing patterns and temperature distributions in a rectangular, slot-ventilated enclosure having obstructions ; a rectangular obstacle with heat flux, solid walls separates the passage and the pig pens, and purlins beneath the ceiling. Air flow patterns were calculated for the cases with and without the purlin, extending 300mm beneath the ceiling. Comparisons of prediction data of Randall & Battams(1976) showed air flow pattern predicted well for the case without the purlin. Heat was accumulated at the corner of the left side of the solid wall and the right-upper region of the simulated pigs. However the air distribution pattern was completely different from data for the case with the purlin. The deviation from the observation may be attributed to the difference of the geometric configuation. Exploring the cause of the deviation should be conducted in a further study. Temperature stratification was also observed due to incomplete mixing. The obstruction in the route of the inlet air jet at inlet should be avoided since most of kinetic energy dissipates at the abstacle duet to impingement.

• 국제초고층학회논문집
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• 제7권4호
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• pp.313-325
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• 2018

Concrete-filled steel tubular (CFST) members are commonly used as composite columns in modern construction. However, the current guidelines for members' fire design (EN1994-1-2) have been proved to be unsafe in case the relative slenderness is higher than 0.5. In addition, the simplified design methods of Eurocode 4 are limited to circular and square CFST columns, while in practice columns with rectangular and elliptical hollow sections are being increasingly used because of their architectural aesthetics. In the last years a large experimental research has been carried out at Coimbra University on the topic. They have been tested concrete filled circular, square, rectangular and elliptical hollow columns with restrained thermal elongation. Some parameters such as the slenderness, the type of cross-section geometry as well as the axial and rotational restraint of the surrounding structure to the column have been tested in order to evaluate their influence on the fire resistance of such columns. In this paper it is evaluated the influence of the boundary conditions (pin-ended and semi-rigid end-support conditions) on the behavior of the columns in case of fire. In these tests it could not be seen a marked effect of the tested boundary conditions but it is believed that the increasing of rotational stiffness increases the fire resistance of the columns.