• Smart Structures and Systems
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• 제15권1호
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• pp.99-117
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• 2015

The Stonecutters Bridge (SCB) in Hong Kong is the third-longest cable-stayed bridge in the world with a main span stretching 1,018 m between two 298 m high single-leg tapering composite towers. A Wind and Structural Health Monitoring System (WASHMS) is being implemented on SCB by the Highways Department of The Hong Kong SAR Government, and the SCB-WASHMS is composed of more than 1,300 sensors in 15 types. In order to establish a linkage between structural health monitoring and maintenance management, a Structural Health Rating System (SHRS) with relevant rating tools and indices is devised. On the basis of a 3D space frame finite element model (FEM) of SCB and model updating, this paper presents the development of an SHR-oriented 3D multi-scale FEM for the purpose of load-resistance analysis and damage evaluation in structural element level, including modeling, refinement and validation of the multi-scale FEM. The refined 3D structural segments at deck and towers are established in critical segment positions corresponding to maximum cable forces. The components in the critical segment region are modeled as a full 3D FEM and fitted into the 3D space frame FEM. The boundary conditions between beam and shell elements are performed conforming to equivalent stiffness, effective mass and compatibility of deformation. The 3D multi-scale FEM is verified by the in-situ measured dynamic characteristics and static response. A good agreement between the FEM and measurement results indicates that the 3D multi-scale FEM is precise and efficient for WASHMS and SHRS of SCB. In addition, stress distribution and concentration of the critical segments in the 3D multi-scale FEM under temperature loads, static wind loads and equivalent seismic loads are investigated. Stress concentration elements under equivalent seismic loads exist in the anchor zone in steel/concrete beam and the anchor plate edge in steel anchor box of the towers.

• 한국자동차공학회논문집
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• 제18권3호
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• pp.37-42
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• 2010

Plastic region tightening is widely used in critical bolted joints in internal combustion engines in order to reduce the engine weight by maximizing the use of load-carrying capacity of bolt. Mechanical behavior of bolt tightened in plastic region under external axial tensile load is investigated for various friction conditions using three dimensional finite element analysis. The behavior of bolt tightened in elastic region as well as that in tensile test are investigated for comparison. Tightening process is simulated by rotating the bolt in order to examine the friction effect realistically. It is revealed that the bolt tightened in plastic region can carry more external load until the joint is opened, and yields at lower bolt load than the bolt tightened in elastic region. The friction coefficient has effect on the yield load, but not on the load-carrying capacity. Moreover, the scatter in the bolt preload due to friction begins with plastic deformation of bolt in the angle tightening control, whereas it begins with the onset of tightening in the torque tightening control. The observations are interpreted with the residual torsional stress in the bolt generated during the tightening.

• 전자공학회논문지C
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• 제36C권10호
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• pp.29-38
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• 1999

본 논문은 조합 논리회로에서의 시험 불가능한 결함(untestable faults)을 확인하는 새로운 알고리즘 RICP(Redundancy Identification using Critical-pair Paths)를 제시한다. 조합 논리회로에서의 시험 불가능 결합은 회로의 과잉(redundancy)에 의해서 발생한다. 회로의 과잉은 팬 아웃 스템(fanout stem)과 재결집 게이트(reconvergent gate)의 영역을 분석함으로서 찾을 수 있다. 시험 불가능한 결함들은 임계 경로의 확장된 개념인 임계-쌍 경로를 이용하여 스템 영역을 분석함으로써 확인되어진다. RICP 알고리즘이 FIRE(Fault Independent REdundancy identification) 알고리즘보다 효율적이라는 것을 보여준다. ISCAS85 벤치마크 테스트 회로에 대한 두 알고리즘의 실험 결과를 비교하였다

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3313-3319
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• 2023

A phenomenological study on CHF in a bilaterally heated annulus with equal heat flux on both sides was experimentally performed. The working fluid of the present test was R-134a. Variation characteristics of CHF and transition of CHF occurrence location were investigated under different pressure, mass flux and quality conditions. With the increase of critical thermodynamic quality, it was found that CHF first occurred on the outer surface of the annulus, then simultaneously occurred on both sides, and finally occurred on the inner surface at relatively high critical quality. After the CHF location transitioned to the inner rod, the sharp fall of CHF in the limiting critical quality region was observed. The critical quality corresponding to the CHF location transition decreased with the increase of mass flux and pressure. Besides, CHF in tube, internally heated, externally heated and bilaterally heated annuli were compared under the same hydraulic diameter conditions. The present study is conducive to improving the understanding of complicated CHF mechanism in bilaterally heated annulus, enriching the experimental database, and providing evidence for developing accurate CHF mechanism model for annuli.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2006년도 춘계학술대회 학술발표 논문집 제16권 제1호
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• pp.199-202
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• 2006

We propose some properties of fuzzy p-value and fuzzy significance level to the test statistics for the fuzzy hypotheses testing. Appling the principle of agreement index, we suggest two method for fuzzy hypothesis testing by fuzzy rejection region and fuzzy p-value with fuzzy hypothesis $H_{f,0}$.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.393-398
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• 2006

This paper classifies driving technologies for AMOLEDs by the driving TFT conditions in pixels. A saturation region operation type driving TFT circuit provides good stability of OLED because of constant current drive. However, complicated compensation circuits are necessary to avoid effect of the TFT characteristics deviation. On the other hand, a linear region operation type driving TFT circuit provides better uniformity of the display image and lower power consumption. However, the stability of OLED is critical because of constant voltage drive.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.847-850
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• 1998

This paper proposes a new scheme of FLR for improving corner breakdown voltage. The major difference from the conventional FLR is to build extra rings and floating field plates in the corner region. In this structure the additional field plate and ring have reduced th electric field at the junction in the corner region. Thus it improves the breakdown characteristics which are critical for obtaining high breakdown voltage.

• 대한지리학회지
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• 제39권1호
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• pp.153-168
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• 2004

본 연구는 우리나라 지리교육과정에 따라 진행되는 지역에 대한 학습이 가지는 문제점과 지역에 대한 개념형성에 작용하는 학생들의 지역인식에 대한 관심에서 시작되었으며 이러한 문제점을 파악하고 개선하기 위해 새로운 지역학습 내용을 구성하는데 목적이 있다. 본 연구에서는 지역학습을 원활하게 이루기 위해 우선 학생들이 지역에 대한 개념을 형성하는 것이 필요하다고 보았으며, 지역개념의 변화 경향을 검토하고 학생들의 이해수준을 고려하여 지역학습의 주요 요소를 추출하였다. 본 연구에서 추출한 지역학습의 주요 요소는 셋으로 나눌 수 있는데 지역의 정의, 지역의 형성, 지역의 체계이다. 지역학습이 이러한 요소를 중심으로 중간적 수준의 학습지역을 설정하여 이루어질 때 학생들은 지역에 대한 보다 의미있는 이해에 도달하게 될 것이다. 그리고 지역학습을 위한 적절한 지역범위 선정에 있어 스케일 개념을 어떻게 적용하는가에 따라 효과적 학습내용 구성의 성공여부가 달려 있음을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제24권5호
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• pp.25-32
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• 2000

In this paper, experiments investigating the high-temperature region heat transfer coefficients for the spray cooling of hot flat plates were performed by down spray water using flat spray nozzles. The heat transfer surface is made of copper and is 100mm in length and 40mm in width and 15mm in thickness. The experimental condition of spray are as follows: temperatures of the water droplets are T=20~$80^{\circ}C$ and droplets volume fluxes are D=0.001565~0.010438$m^3/m^2s$. Next, correlating equations for the heat transfer characteristics of spray cooling in the high temperature region are developed from the effects of droplets volume flux and the surface temperature of heat transfer plate.

• 한국정보통신학회논문지
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• 제7권7호
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• pp.1551-1555
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• 2003

본 논문은 뇌 자기공명영상에 대해 셀룰러 오토마타를 이용하여 뇌 영역을 추출한 연구이다. 입력된 뇌 자기공명영상의 배경영상을 임계값으로 제거한다. 임계값은 히스토그램 분석기법으로 설정된다. 분리된 영상정보는 셀룰러 오토마타 규칙을 적용하여 뇌 영역을 추출한다. 실험결과 평균 PSNR은 42㏈이상 향상되었으며, 상관도 측정 결과 98%이상 일치되었다. 본 연구 결과는 의료 뇌 영상의 자동 진단 시스템 등에 활용 할 수 있다.