• 수산해양기술연구
• /
• 제35권2호
• /
• pp.118-128
• /
• 1999

본 연구에서는 실물 어구를 이용한 해상실험을 통하여 예망 중인 어구의 망구 형상을 해석하기 위해서 예망 속도, 어구의 저항, 전개판의 간격, 망고 등을 계측ㆍ분석하였다. 또한 망구 형상을 이론적으로 계산하기 위해서 망구의 형상을 지배하는 뜸줄, 발줄 및 옆줄의 모양을 현수곡선으로 간주하고 수학모텔을 기술하여 수치해석 하였고, 이 결과를 실제 측정된 값과 비교하여 모텔의 타당성을 검토하였다. 본 실험에 대한결과를 요약하면 다음과 같다. 1. 선속의 변화에 따라 크게 변하는 요소로는 장력과 망고였고, 끌줄 길이의 변화에 민감하게 반응한 것은 어구 수심과 전개판의 간격이었다. 2. 계측된 트롤 어구의 상태량을 토대로 뜸줄 및 옆줄의 형상을 수치해석한 결과, 선속이 증가함에 따라 뜸줄 및 발줄의 폭과 옆줄의 높이는 감소하였고, 뜸풀 및 옆줄 중앙부의 처짐 정도는 증가하였다. 3. 예망속도에 따른 망고변화에 대하여 수치해석한 결과와 실제 실험에서 얻은 데이터를 비교한 결과, 비교적 양호한 결과를 얻을 수 있었다. 4. 수치해석한 결과로부터 망구의 형상을 추정한 결과, 선속이 증가함에 따라 횡축으로 긴 직사각형의 형상이 나타났으며, 횡축 및 종축 모두 크기가 감소하였다.

• 한국농촌건축학회논문집
• /
• 제17권3호
• /
• pp.11-18
• /
• 2015

This study is aimed to clarify the transitional characteristics of old roads and alleys lasting more than 100 years(1915-2015) in traditional urban area(Seongan-dong) of cheongju, historic inland and castle city of Korea. Cheongju castle had been completely destroyed In 1915, and urban structures been also altered last 100 years from 2015 now. Periodically, after destruction of castle, existing roads were extended and transformed to straight line for connecting with around. Expanding urban area to all directions of castle boundary in 1930-40s, town planning were created. These projects were completed in 1960-70s, the street network was built as they are. Since the 1980s, changes had been occurred in the details such as an extension of the unexecuted roads, the opening of fire lane in a block, and etc. In change and construction of roads, urban district plan in 1939 and reorganization since 1967 were planned and established with the type, location, and width of the large, medium and small roads based on data before destruction of castle. Except the width of 25m Sajikro(large3-1) and Sangdangro(large3-8,9,10), the width of 15m Namsaro(medium2-1) and Namjuro (medium2-4) as an extension of the roads, the other roads were small roads equivalent to the existing roads, and so remain intact figure of streetscape. As such, roads of east-west and north-south cross type, roads showing the outline of Cheongju castle fortress, and alleys outside the south gate are sustained in Seongan-dong of cheongju as historic urban area, and also present roads are delicately executed to the existing urban fabric.

• 콘크리트학회논문집
• /
• 제24권2호
• /
• pp.205-214
• /
• 2012

균열폭은 콘크리트 구조물의 사용성을 평가하는 측면에서는 매우 중요하다. 균열폭을 일정값 이하로 유지할 수 있다면 낮은 투수성을 유지할 수 있으므로 콘크리트의 피복만으로도 염소이온에 의한 부식을 방지할 수 있다. 따라서 내구적인 구조물을 설계하기 위해서는 인장 균열에 대한 충분한 정보가 필요하다. 그러나 균열폭을 정확하게 계측하는 데는 몇 가지 어려움이 있다. 먼저, 균열의 생성 위치를 미리 알기 어렵다. 또한 변형률 게이지 등 탄성영역에서 사용되는 게이지는 사용할 수 없다. 이러한 문제를 극복하기 위해서 화상상관기법 및 고해상도 CCD를 이용한 균열 및 변위계측 시스템을 개발하였다. 이를 통해서 임의의 위치에 생성되는 인장균열폭을 측정하는 방법을 제시하였다. 변위계측 정밀도 검증을 실시한 결과 평균오차는 0.069 픽셀, 표준편차는 0.050 픽셀이었다. UHPC를 이용하여 직접인장 실험을 수행하였다. 노치 구역과 비노치 구역에서 각각 균열을 측정하는 방법을 제시하고, 하중단계에 따라서 클립인 게이지의 결과와 비교하여 설명하였다. 시편의 전면에서 변위벡터를 구성하고, 등변위도 및 변형률도를 작성하였다. 다양한 실험에 적용할 수 있는 범용의 기법이기 때문에 임의의 균열폭 혹은 전면변위 측정 분야에서 많이 활용될 수 있을 것이다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1994년도 가을 학술발표회 논문집
• /
• pp.231-234
• /
• 1994

Concentrated stresses due to the tunnel excavation easily cause failure around opening in the soft rock mass layer. Thus, while excavatng tunnel in the soft rock mass layerm it is very important to predict the possibility of failure or yielding zones around tunnel boundary. There are two typical methods to predict these; 1) the analysis of field monioring data and 2) numerical analysis. In this study, it was attempted to describe the time-dependent or progressive rock mass manner due to the continuous failure and fracturing caused by surrounding underground openings using the second method. In order to apply the effects of progressive failure underground, an iterative technique was used with the Hoek and Brown rock mass failure theory. By developing and simulating, three different shapes of twin tunnels, this research simulated and estimated the proper size of critical pillar width between tunnels, distributed stresses on the tunnel sides, and convergences of tunnel crowns. Moreover, results out progressive failure technique based on the Hoek and Brown theory were compared with the results out of Mohr-Coulomb theory.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.31-36
• /
• 2004

Defective components of interest include not only homogeneous components, but also components with weldments where tensile properties vary across the weldment. Noting that the region near the weldment is the most vulnerable place for crack initiation and subsequent growth, defect assessment methods for homogeneous structure. Moreover, weldment width and crack location also affects the deformation and fracture behavior of the welded joints. These weld characteristics can evaluate using plastic limit load. So in this paper, evaluate plastic limit load both full circumference part-throughwall cracked pipes and circumference through-wall cracked pipes considering weld characteristics. And using evaluate results, proposed J-integral and crack opening displacement(COD) estimate method based on reference stress method.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.67-69
• /
• 2004

This paper describes an approach to design a interior permanent magnet motor(IPM motor) for the reduction of cogging torque. The magnitude of the torque ripple and cogging torque in a interior permanent magnet motor(IPM motor) are generally dependent on several major factors: the shape of stator tooth tip, slot opening width, air gap length, the shape of barrier preventing flux leakage of magnets, magnet configuration and magnetization distribution or magnet poles. In this paper, the IPM BLDC motor is designed considering a saturated leakag flux between the barriers on the rotor for increasing the efficiency and decreasing the magnitude of the cogging torque. Analytical model is developed for the IPM BLDC motor with a concentrated winding stator. The results verifies that the proposed design approach is very efficient and effective in reducing the cogging torque and the torque ripple of the IPM BLDC motor to be used in an electric vehicle.

• 한국자동차공학회논문집
• /
• 제7권7호
• /
• pp.214-220
• /
• 1999

In order to use effectively a machinery part with fillet, it is necessary to determine a proper fillet shape in design step, Study of such problem by fracture mechanical criterion is rare. So, this paper focuses on the design of fillet radius in fracture mechanical aspect. Finite element method was used to obtain crack tip stress intensity factor. Stress intensity factor was calculated by COD(crack opening displacement0method proposed by Ingraffea and Manu. The parameter used in this study are thickness ration, filet radium and crack length . If fillet radius increase , crack propagation may be accelerated. Critical crack length is inversely proportional to fillet radius.

• Journal of Astronomy and Space Sciences
• /
• 제20권3호
• /
• pp.163-174
• /
• 2003

The motion of 3C 120 Jet relative to the core is reasonably uniform and the VLBI scale jet connects outwards to a VLA ~ 100kpc scale. We measured the jet width variation from the center and found some indication of a power law which indicates the jet expands roughly with a constant opening angle and a constant flow velocity, $V_{f}{\cong}c$, from subparsec scales to ~ 100 kpc. With such a constant flow velocity and based on other physical parameters deduced from observed emission characteristics of the jet, we have established an equipartition jet model which might accommodate the basic parameters of the jet on subparsec scales, with which one can fit the radio intensities over all the scale of the jet even to ~100 kpc.

• 한국마이크로전자및패키징학회:학술대회논문집
• /
• 한국마이크로전자및패키징학회 2002년도 International Symposium
• /
• pp.79-94
• /
• 2002

Root cause -Thermal expansion coefficient mismatch -Tape warpage -Initial die crack (die roughness) Guideline for failure prevention -Optimized tape/Substrate design for minimizing the warpage -Fine surface of die backside Root cause -Thermal expansion coefficient mismatch - Repetitive bending of a signal trace during TC cycle - Solder mask damage Guideline for failure prevention - Increase of trace width - Don't make signal trace passing the die edge - Proper material selection with thick substrate core Root cause -Thermal expansion coefficient mismatch -Creep deformation of solder joint(shear/normal) -Material degradation Guideline for failure Prevention -Increase of solder ball size -Proper selection of the PCB/Substrate thickness -Optimal design of the ball array -Solder mask opening type : NSMD -In some case, LGA type is better

• 디지털산업정보학회논문지
• /
• 제9권2호
• /
• pp.17-22
• /
• 2013

In this paper, we propose a concrete crack detection method using shape properties. It is based on morphology algorithm and crack features. We assume that an input image is contaminated by various noises. Thus, we use a morphology operator and extract patterns of crack. It segments cracks and background using opening and closing operations. Morphology based segmentation is better than existing integration methods using subtraction in detecting a crack it has small width. Also, it is robust to noisy environment. The proposed algorithm classifies the segmented image into crack and background using shape properties of crack. This method calculates values of properties such as the number of pixels and the maximum length of the segmented region. Also, pixel counts of clusters are considered. We decide whether the segmented region belongs to cracks according to those data. Experimental results show that our proposed crack detection method has better results than those by existing detection methods.