• 한국환경복원기술학회지
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• 제20권1호
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• pp.55-75
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• 2017

The purpose of this study is to present the basic data for restoration of physical stream environment by analyzing habitat variables because habitat environment is changed due to the construction of waterfront space in urban streams. Assessment results of 10 habitat variables(three divisions) were almost same as optimal condition, in the reach of reference stream where there are no stream crossing structures and channel alteration. Assessment results of reaches in urban rivers, where streams were improved on water-friendly recreation activities, appeared to be marginal condition. Because habitat environment got worse due to stream improvement works such as construction of weir for water landscape, stepping stones for walking, low water revetment and high water revetment, and high water channel. In addition, in the case of mid gradient stream, the frequency of riffles was small or not existed because the intervals of the river crossing structures was short. In the case of mild stream types, the diversity of the pool was damaged due to the deposition of sludge in the upstream pool of weir and the installation of low water revetment.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.116-122
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• 2009

In this paper, a robust method is developed to locate the irises of both eyes. The method doesn't put any restrictions on the background. The method is based on the AdaBoost algorithm for face and eye candidate points detection. Candidate points are tuned such that two candidate points are exactly in the centers of the irises. Mean crossing function and convolution template are proposed to filter out candidate points and select the iris pair. The advantage of using this kind of hybrid method is that AdaBoost is robust to different illumination conditions and backgrounds. The tuning step improves the precision of iris localization while the convolution filter and mean crossing function reliably filter out candidate points and select the iris pair. The proposed structure is evaluated on three public databases, Bern, Yale and BioID. Extensive experimental results verified the robustness and accuracy of the proposed method. Using the Bern database, the performance of the proposed algorithm is also compared with some of the existing methods.

• Computers and Concrete
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• 제29권2호
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• pp.69-79
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• 2022

For long underground box utility tunnels, post-tensioned precast concrete is often used. Between precast tunnel segments, sealed waterproof flexible joints are often specified. Fault displacement can lead to excessive deformation of the joints, which can lead to reduction in waterproofing due to diminished contact pressure between the sealant strip and the tunnel segment. This paper authenticates utilization of a finite element model for a prefabricated tunnel fault-crossing founded on ABAQUS software. In addition, material parameter selection, contact setting and boundary condition are reviewed. Analyzed under normal fault action are: the influence of fault displacement; buried depth; soil friction coefficient, and angle of crossing at the fault plane. In addition, distribution characteristics of the utility tunnel structure for vertical and longitudinal/horizontal relative displacement at segmented interface for the top and bottom slab are analyzed. It is found that the effect of increase in fault displacement on the splice joint deformation is significant, whereas the effects of changes in burial depth, pipe-soil friction coefficient and fault-crossing angle on the overall tunnel and joint deformations were not so significant.

• 한국전자파학회논문지
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• 제7권5호
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• pp.430-439
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• 1996

인쇄회로기판(PCB) 설계시 회로 동작 상 혼신(crosstalk)의 영향도를 예측하는 것이 중요하다. 본 논문에서는 평행 또는 교차선로 간의 혼선을 FDTD 방볍에 의해 다루었다. 이 모델들은 PCB 선로의 대표적인 형태이며 그 혼선은 전자파 장해(EMI)의 주요 요인이 된다. 혼선의 영향도를 평행선로와 교차선로의 선로 간 간격 및 길이 변화에 따라 계산하였다. 시간 및 주파수 영역에서의 결과가 논의되고 MDS(microwave design system) 및 HFSS(high frequency structure simulator)를 사용한 주파수 영역 결과와 비교된다. 그로부터 FDTD 방볍이 해석 모델에 있어 적용범위가 넓고 계산 시간을 줄일 수 있음을 보인다.

• Smart Structures and Systems
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• 제16권3호
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• pp.555-577
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• 2015

In the work at hand, the development of a morphing flap, actuated through shape memory alloy load bearing elements, is described. Moving from aerodynamic specifications, prescribing the morphed shape enhancing the aerodynamic efficiency of the flap, a suitable actuation architecture was identified, able to affect the curvature. Each rib of the flap was split into three elastic elements, namely "cells", connected each others in serial way and providing the bending stiffness to the structure. The edges of each cell are linked to SMA elements, whose contraction induces rotation onto the cell itself with an increase of the local curvature of the flap airfoil. The cells are made of two metallic plates crossing each others to form a characteristic "X" configuration; a good flexibility and an acceptable stress concentration level was obtained non connecting the plates onto the crossing zone. After identifying the main design parameters of the structure (i.e. plates relative angle, thickness and depth, SMA length, cross section and connections to the cell) an optimization was performed, with the scope of enhancing the achievable rotation of the cell, its ability in absorbing the external aerodynamic loads and, at the same time, containing the stress level and the weight. The conceptual scheme of the architecture was then reinterpreted in view of a practical realization of the prototype. Implementation issues (SMA - cells connection and cells relative rotation to compensate the impressed inflection assuring the SMA pre-load) were considered. Through a detailed FE model the prototype morphing performance were investigated in presence of the most severe load conditions.

• 대한한의학원전학회지
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• 제32권1호
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• pp.145-158
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• 2019

Objectives : This study attempts to identify the concept of Link meridian in previous medical books, and explore how Link meridian theory was used in a clinical practice focusing on YeTianshi. Methods : This study looked at the medical books related to acupuncture and moxibustion in the past and the part where Link meridian is mentioned in the annotations of "Huangdineijing" and "Nanjing", and examined how medical doctors prior to YeTianshi used Link meridian in a clinical practice. And then this study examined treatment cases in the medical records of YeTianshi. Results ＆ conclusions : Yang-Link meridian and Eum-Link meridian were arranged as ascending route by the majority of medical doctors. However, there are doubts because startpoints of them are not "Jeyanghoe" and "Jeeumgyo" respectively described in "Nanjing". Link meridian is thought to be a structure that connects each meridian passing through crossing points with each crossing point itself as a starting point. Thus, Link meridian can be seen as a role in strengthening the connection of crossing meridians and balancing and controlling those meridians centering on each crossing point. The point that YeTianshi's identifying that pathology of Eight extra meridians associates with liver and kidney(肝腎) to be a symptom of weakness, and his development of Link meridian's physiology and pathology through the relationship with other Eight extra meridians are thought to be more advanced than the previous medicine prior to YeTianshi.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.265-268
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• 2005

This paper discusses a strategy and status for development and operation of durability mock-up test facilities for offshore structures. The strategy is examplified and facilitated using an offshore transmission tower crossing the West sea and the Shihwha lake, which was designed and constructed 345kV T/L lines transmitting power from Yeong-Heung fossil power plant to Seoul metropolitan area. Various data for corrosion protection, aging, life-prediction of concrete and steel offshore structures can be obtained using the proposed mock-up test facility. Acquired data will be used for further research on durability, life-prediction, and retrofit of structures. It is important to maintain the safety of 345 kV Yeong-Heung transmission line crossing the Shihwha lake because the offshore structure is one of the critical electric facilities transmitting large power to the metropolitan area. Operation of the offshore transmission tower mock-up is expected to make a significant contribution to stable power supply.

• Journal of Power Electronics
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• 제15권1호
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• pp.78-85
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• 2015

This paper presents a new structure of single-stage flyback power factor correction (PFC) converter with a controllable coupled negative magnetic feedback (NMF) winding. NMF winding is used to reduce the bulk capacitor voltage at high line voltages and light loads. However, it would cause line current distortion at zero crossing condition. In the proposed circuit, a series winding is used with NMF inductor to eliminate the NMF inductor at low line voltages. As a result, the dead angle of the input current, near zero voltage crossing, is eliminated and the power factor is increased. The presented experimental results of the proposed PFC converter confirm the integrity of the new idea and the theoretical analysis.

• 한국방재학회 논문집
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• 제9권1호
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• pp.41-47
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• 2009

강바닥판의 횡리브 복부판에서는 전단력과 비틀림 모멘트가 작용하는 동시에 종리브의 비틀림으로 인한 면내외 변형이 작용하기 때문에 교차부와 컷아웃부에 응력집중현상이 발생한다. 본 연구는 피로균열 발생사례가 가장 높은 교차부와 컷아웃부에서의 응력집중현상 완화를 통하여 피로성능을 향상시킬 수 있는 구조상세를 개발하기 위하여 수행되었다. 다이아프램의 설치는 교차부와 컷아웃부에서의 응력집중현상 완화효과에 유리한 구조상세이다. 다이아프램의 위치에 대한 응력집중의 양상을 분석하기 위해서 다이아프램 위치를 횡리브 복부판과 일치된 곳으로부터 교축방향으로 이동시켜 가며 그 응답을 수치적으로 분석하였다. 또한 컷아웃폭을 대상으로 매개변수해석을 수행하여 최대응력 감소효과를 분석하였다. 그 결과 다이아프램은 횡리브 복부판과 횡리브 축 방향으로 일치되도록 설치하는 것이 응력집중현상을 완화시켜 구조성능 개선에 유리한 구조상세임을 알 수 있었다. 그러나 어떤 경우에도 다이아프램을 설치하지 않은 경우보다는 설치한 경우가 피로성능에 유리함을 알 수 있었다. 컷아웃폭은 바닥강판으로부터 종리브 바닥판면까지의 거리($y_{gotal}$)에 대한 바닥강판으로부터 컷아웃부의 종리브와 횡리브 교차점까지의 거리($y_i$)의 비($y_i/y_{total}$) 0.85가 되도록 컷아웃폭을 설정하는 경우가 구조성능 개선에 유리한 구조상세임을 알 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.322-325
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• 2005

TTX(Tilting Train eXpress) is being designed for improving the speed of conventional railway. The purpose of this study is to evaluate energy absorbing capacity and driver's survivability for a design candidate of the front end structure of TTX. A FE model with honeycomb block, under frame, and body frame is generated for crash simulation. Based on a level-crossing accident scenario, numerical simulation is performed using LS-DYNA. The results of crash analysis show that strength improvement of the current front end structure design candidate is needed to ensure driver safety.