• Journal of Welding and Joining
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• 제19권4호
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• pp.429-436
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• 2001

The effect of welding condition on the microstructures of the weld metal in A7N01 welded by $CO_2$ laser was investigated. The number of ripples was increased with decreasing power and increasing welding speed. In the bead without ripple lines, the subgrain microstructures distribution from the fusion line toward the center of the bead were in the order of cellular, dendritic and equiaxed dendrite. However, in the bead with ripple lines, cellular and dendritic were formed between the fusion boundary and the ripple line. Inaddition, those structures were also observed between the ripple line. Equiaxed dendrites were formed only at the center line region. Cellular and dendritics formed near the ripple line were larger than those formed near the fusion boundary. The cooling rates estimated by the dendrite arm spacing were in the range of 200 to 1150oC/s. Cooling rate was increased with decreasing the power and increasing the welding speed. Mg and Zn segregated at the boundaries of cellulars and dendritics, Mg was segregated more than Zn. The segregation of Mg and Zn decreased with increasing cooling rate. Hardness of the weld metal was lower than that of the base metal in all welding conditions and increased as the cooling rate increased.

• Ocean and Polar Research
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• 제26권4호
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• pp.669-678
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• 2004

Coastal states are adopting maritime boundary delimitation as their primary maritime policy because maritime jurisdiction directly relates to vast economic interest. This becomes specially important and sensitive when complex maritime boundary issues are involved between neighboring coastal states. China has not actively carried out nor declared maritime boundary delimitation until recently with any country except Agreement between China and Viet Nam on the demarcation of the territorial water, the exclusive economic zones and the continental shelf of China and Vet Nam in the Gulf of Tonkin on 25 December 2000 (hereinafter, the Gulf of Tonkin Agreement). The principles that governs maritime boundary delimitation are to consider primarily an agreement between States concerned, however, if no agreement can be reached, all relevant circumstances are considered to achieve an equity between concerned States. Relevant circumstances are length of coastline, form of coastline, existence and position of island or islands, speciality of geology/topography, and factor of economy and deffnce. Factors which sinologists are considering in regard to continental shelf delimitation of the Yellow Sea are as follows; i) geographical factor, ii) geological factor, iii) topographical factor, iv) environment and ecological (factor, v) historic interest, and vi) social and economic interest. The 'Gulf of Tonkin Agreement' is completed by basically applying the principle of delimitation according to median line which seems that China has adopted the maritime boundary delimitation principle of 'half and half' which was the intention of chinese government. At the same time, China recognized Viet Nam's dominion and sovereign right over the partial exclusive economic zone and the continental shelf of Dao Bach Long Vi in Gulf of Tonkin. This case can be considered as an example of mutual concession or compromise in delimiting maritime boundary for states of concerned.

• 한국멀티미디어학회논문지
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• 제14권4호
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• pp.538-545
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• 2011

최근, 인터넷에 다양한 컨텐츠가 있으며, 특히 만화영상은 인기 있는 디지털 컨텐츠 중의 하나이다. 이러한 만화영상은 대부분 스캐너에 의해 스캔되며, 크기, 기울기, 경계선 부분의 여백 등이 정규화되어 있지 않다. 이와 같은 정규화 과정은 만화영상 분석에서 매우 중요한 단계로, 만화영상의 외곽 경계사각형을 검출하는 방법으로 정규화를 수행할 수 있다. 본 논문에서는 그래디언트 라돈 변환을 사용하여 만화영상에서 외곽의 경계사각형을 검출하는 방법을 제안한다. 만화영상에서 경계 사각형의 변의 후보인 선분을 검출하기 위하여 그래디언트 정보를 이용한 라돈 변환을 적용하고, 후보 선분과 지역 히스토그램을 이용하여 최종 외곽의 경계사각형 검출하였다. 제안 방법으로 만화 영상에서 효과적으로 외곽의 경계사각형을 검출함을 실험으로 보였다.

• 경영과학
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• 제13권2호
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• pp.1-11
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• 1996

Two different methods to extract the license plate area of a vehicle have been used for automatic recognition purposes. One method is with a color vision system and the other is with an edge detecting operator. The system with color vision has some problems if the colors of license plate and vehicle's body are similar. The various plate colors in Korea also drops the system performance. The edge detecting operator also has a problem for a real time processing since it performs on all pixels of the scene. In this paper a possible method using gray level vision system and available pre-known information of license plates is suggested. The suggested procedure searches the lower boundary of the plate by counting high contrast points between one and near pixel from the bottom line of the scene. It finds the upper boundary from the bottom line by adding number plate height after finding the lower boundary. The left and right boundaries are found by similar processes.

• 대한기계학회논문집
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• 제18권6호
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• pp.1474-1482
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• 1994

In order to study the influence of a circular inclusion on a stress field neat a crack tip, mutual interference of a crack and the circular inclusion is analyzed by using the two dimensional boundary element method program made for the analysis of a bimaterial inclusion. The stress intensity factor of an inclusion which has small stiffness is a little greater than that of large stiffness in the near-by crack tip, and similar values tends to appear for distant crack tips. A line crack shows the repetition phenomena which caused by stress mutual interference depending on the radius and stiffness of an inclusion, and the repetition phenomena becoms weak in the inclusion which has large stiffness. Stress mutual interference shows repetition phenomena after extension of a line crack by the length of the radius of the inclusion which has small stiffness.

• 한국레이저가공학회지
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• 제11권3호
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• pp.10-15
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• 2008

This study is aimed to analyse the laser glass bonding process numerically. Due to the viscoelastic behaviour of glass, the extremely large deformation of the frit seal is resulted continuously over the transition temperature, so that the thermal boundary condition be changed in the entire calculation process. The commercial FEM algorithm is restrictively able to remesh the large geometrical boundary shape and to adapt the boundary conditions simultaneously. According to our manual adaptation of increasing the laser line intensity to 700 mW/mm, it is possible to estimate the thermal glass bonding process under the fracture stress in principle. But it should be studied further in the case of high laser line intensity.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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• pp.283-292
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• 1999

Temperature prediction model was developed for on-line application to plate rolling mills of POSCO. The adequate boundary conditions of heat transfer coefficients were obtained by comparing the predicted temperature with the measured temperatures taken by measuring system in plate rolling mill of POSCO. In obtaining the boundary condition which minimize the mean and standard deviation of the difference between prediction and measurement, orthogonal array for experimental design was used to reduce the calculation time of large data set. To predict the temperature drop at four edge of plate in one dimensional model, the energy change by heat transfer though directions perpendicular to thickness direction was treated like that by deformation. And the heat transfer through four edge directions was inferred from that through thickness direction with two coefficients of depth and severity of temperature drop at the edge. The boundary condition for the depth and severity of temperature drop were also determined using the measured temperature.

• 한국생산제조학회지
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• 제20권2호
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• pp.139-144
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• 2011

This paper presents a boundary element application to determine the optimal impressed current densities at defect position on the pipe line. In this protection paint, enough current must be impressed to lower the potential distribution on the metal surface to the critical values. The optimal impressed current densities are determined in order to minimize the power supply for protection. This inverse problem was formulated by employing the boundary element method. Since the system of linear equations obtained was ill-conditioned, including singular value decomposition, conjugate gradient method were applied and the accuracies of these estimation. Several numerical examples are presented to demonstrate the practical applicability of the proposed method.

• 화약ㆍ발파
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• 제16권3호
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• pp.16-24
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• 1998

Methods of Rock fragmentation are used rock of housing repair development at KU-SAN DONG area in seoul Youn-Pyong Ku. So, Theorical analyses of the effect of vibration and frequency on structural damage around old housed also discussed. The results can be summarized as follows: 1. A area(Rock area not more than 15m Ku-San Mention) Some Empirical equations were obtained $V=K\{{\frac{D}{W}}1/3\}^{-n}$ where the values for n and K are estimated to be -1.64 and 94 respectively, this values were obtained only theorical analyses. If we have 125g charge this area is impossible blasting operation, so this area must be worked by SRS(Super Rock Splitter) method. 2. B area(Rock area from 15m to 25m in a boundary line from Ku-San Mention) This area charge is about 125g in a delay time by some empirical equation s. So, this area can be blasting operations by small charge. 3. C area(Rock area from 25m to 35m in a boundary line from Ku-San Mention) This area charge is about 500g in delay time by some empirical equation s. So, this area can be blasting operations by middle charge. 4. D area(Rock area more then 35m in a boundary line from Ku-San Mention) This area charge is about 1000g in a delay time by some empirical equation s. So, this area can be blasting operations by middle charge.

• 한국통신학회논문지
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• 제17권1호
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• pp.80-89
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• 1992

화상처리는 전처리, 중간표현, 최종 인식의 3단계로 구분하여 처리할 수 있다. 본 논문에서는 전처리 단계에서 구해진 에지로 둘러싸인 예영역들로부터 라벨링 기법으로 화상을 구분된 영역의 집합으로 표현한 후 각 영역을 둘러 싸고있는 외측 경계과 내측 경계를 세그먼트화하여 각 세그먼트들에 대한 영역의 정보, 세그먼트 번호, 시작점과 끝점의 정보, 적용된 직선 곡선의 종류 및 이들의 개수 정보 리스트에 대한 데이터 구조를 만드는 중간 표현 단계에 대한 알고리즘을 제안하고, 구해진 데이타 구조를 이용 화상을 재구성한 결과 오차가 한 화소 범위내의 신뢰성이 있음을 확인하였다.