• 한국안전학회지
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• 제15권2호
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• pp.13-21
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• 2000

Under the mixed mode loading, it has been known that the influence of non-singular terms in the stress fields is serious, because the critical distance, ${\gamma}_o$ - the distance of nonlinear elastic region near the crack tip has no negligible value. In this paper, it has been studied on the influence of non-singular terms, T-stress, and the case of T=0, ${\sigma}cos^2{\beta}$, ${\sigma}cos(2{\beta})$ and $0.05{\sigma}cos(2{\beta})$, under uniaxial tension and compression. It has been seen that the T-stress of ${\sigma}cos(2{\beta})$ has better than others as comparing to the experimental data.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.82-88
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• 2002

A simple beam subjected to a uniformly distributed tangential follower force and the successive two moving spring-mass systems upon it constitute this vibration system. The influences of the velocities of the moving spring-mass system, the distance between the successive two moving spring-mass systems and the uniformly distributed tangential follower force have been studied on the dynamic behavior of a simple beam by numerical method. The uniformly distributed tangential follower force is considered within its critical value of a simple beam without the successive two moving spring-mass systems, and three kinds of constant velocities and constant distance of the successive two moving spring-mass systems are also chosen. Their coupling effects on the transverse vibration of the simple beam are inspected too.

• 소성∙가공
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• 제24권1호
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• pp.28-36
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• 2015

After a short review of the iterative optimal blank method, a new method of measuring the shape error for stamped parts with 3D contour lines, which is an essential component of the optimal blank design, is proposed. When the contour line of the target shape does not exist in a plane, but exists in 3D space, especially when the shape of the target contour line is very complicated as in the real automotive parts, then the measurement of the shape error is critical. In the current study, a method of shape error measurement based on the minimum distance is suggested as an evolution of the radius vector method. With the proposed method, the optimal blank shapes of real automotive parts were found and compared to the results of the radius vector method. From the current investigation the new method is found to resolve the issues with the radius vector method.

• Journal of Welding and Joining
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• 제34권6호
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• pp.20-27
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• 2016

This study deals with the proper conditions of the trail rolling method (TRM) for the prevention of the buckling welding distortion at the AA5083 GMA butt weldment. For it, the effect of the working conditions of TRM including the rolling depth and the rolling distance between the welding torch and the roller on the longitudinal welding shrinkage force of the weldment was evaluated by using 3 dimensional thermo-mechanical FE analyses. The longitudinal welding shrinkage force inducing the buckling welding distortion at the GMA butt weldment was mitigated with an increase in the rolling depth and the rolling distance between the welding torch and the roller. Based on the results, the proper conditions of trail rolling method were established to reduce the longitudinal welding shrinkage force of the GMA butt weldment to below the critical value corresponding to the bucking distortion.

• 한국항해항만학회지
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• 제33권2호
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• pp.105-110
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• 2009

Shipwaves am have harmful effects on ships working on the sea, in a harbour or navigational channel and caused beach erosion, seawall destruction. This study aims to investigate describe the characteristics of the wave pattern generated by an individual model ship tested at different velocities and hull forms for a given water depth and to investigate the variations at a given distance from the sailing line under the same conditions. As a result, the angles a's by model ship tests are smaller than those by real ship ones. Wave heights decreases with an increasing the mid-ship cross sectional area $A_s$. The maximum wave height and period increase rapidly in the subcritical speed, and beyond the critical speed the height and period decrease with increasing depth Froude number. And the period keeps constant with the distance from the sailing line.

• 한국정보통신학회논문지
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• 제12권3호
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• pp.469-477
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• 2008

MANET(Mobile Ad-hoc NETwork)의 표준 라우팅 프로토콜인 AODV(Ad-hoc On-demand Distance Vector)에서는 최단거리만이 고려되므로 중요한 위치에 있는 노드에 트래픽이 집중될 수 있다. 따라서 노드의 배터리가 급격히 소모되어 네트워크 전체의 생존시간이 줄어드는 문제가 발생 할 수 있다. 본 논문에서는 노드의 에너지 정보를 고려한 경로 변경이 가능한 AODV 라우팅 개선 방안을 제안하고 시뮬레이션을 통해 그 효과를 확인한다.

• 한국가시화정보학회지
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• 제18권3호
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• pp.52-60
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• 2020

When a bubble reaches a free surface, a bursting of the bubble produces a high speed jet. Despite its practical importance, significant effort has been devoted to investigate a bursting jet by a single bubble near a free surface. In the present study, we perform numerical simulations of bubbles in a tandem arrangement at Bo=0.05. The configuration of the tandem bubbles is systematically varied by changing a radius of a following bubble (RF) and the gap distance between two bubbles (L). Compared to a single bubble case, we show that the bursting bubble in the tandem arrangement accelerates, and the jet velocity increases. Moreover, we find that a critical gap distance at which the jet velocity unexpectedly changes exists in the tandem case.

• Geomechanics and Engineering
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• 제33권1호
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• pp.53-63
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• 2023

Rock disturbance caused by blasting and stress relaxation is commonly observed during excavation. As the distance from the source of disturbance increases, the degree of disturbance decreases, and rock at a large depth does not experience disturbance. However, in stability analyses, a single value of disturbance is often applied to the entire rock mass, which leads to underestimated results. In this study, this modeling mistake is addressed by considering realistically varying rock disturbance. The safety of infinite slopes in a disturbed rock mass with a strength governed by the Hoek-Brown failure criterion is investigated based on the kinematic approach of limit analysis. The maximum disturbance is assigned to the outermost slope face because it is directly exposed to blasting damage and dilation, and the disturbance progressively decays with distance in the rock mass. The safety analysis results indicate that the assumption of uniform disturbance in the entire rock mass leads to underestimation of the rock strength and safety on infinite rock slopes. A critical slip surface appears to be within the disturbed rock layer as well as the interface between the disturbed upper rock and undisturbed lower rock.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권3호
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• pp.1014-1034
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• 2015

Location information of sensor nodes plays a critical role in many wireless sensor network (WSN) applications and protocols. Although many localization algorithms have been proposed in recent years, they usually target at dense networks and perform poorly in sparse networks. In this paper, we propose two component-based localization algorithms that can localize many more nodes in sparse networks than the state-of-the-art solution. We first develop the Basic Common nodes-based Localization Algorithm, namely BCLA, which uses both common nodes and measured distances between adjacent components to merge components. BCLA outperforms CALL, the state-of-the-art component-based localization algorithm that uses only distance measurements to merge components. In order to further improve the performance of BCLA, we further exploit the angular information among nodes to merge components, and propose the Component-based Localization with Angle and Distance information algorithm, namely CLAD. We prove the merging conditions for BCLA and CLAD, and evaluate their performance through extensive simulations. Simulations results show that, CLAD can locate more than 90 percent of nodes in a sparse network with average node degree 7.5, while CALL can locate only 78 percent of nodes in the same scenario.

• 한국의학물리학회지:의학물리
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• 제5권1호
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• pp.67-74
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• 1994

선량분포특성은 거리의 제곱에 반비례하기 때문에 근접조사에서 선원의 조그마한 오차는 선량계산에서 큰 차이를 초래할 수 있어서 선원의 정확한 거리 이동과 그에 따른 critical organ에 조사되는 선량의 정확도는 자궁경부암 환자의 치료성적에 결정적인 역할을 할 수가 있다. 특히 High Dose Rate의 RALS(Remote After Loading System)에서 선원의 정확한 calibration은 자궁경부암 환자의 치료에서 선량분포에 지대한 영향을 미치며 나아가 이 선량분포는 치료후 나타나는 재발 및 합병증이나 휴유증의 발생에도 큰 영향을 미치게 된다. 본 연구에서는 실제 RALS시 선원의 거리 이동을 측정하여 치료계획용 computer에서 계산된 선원간의 거리 이동과 비교 검토하였으며 Rectum 위치에 chamber를 삽입하여 실제 Rectum에 조사되는 선량과 computer에서 계산된 값들을 비교검토하였다. Tandem Source을 1cm 간격으로 거리를 이동하면서 실험을 되풀이 한 결과 처음 monitor로 1cm을 이동할 때 측정치가 0.8cm 이동한 것으로 나타났으며, 2번째부터 5번째까지의 거리 이동에서는 monitor의 값과 측정치의 값이 정확하게 일치하였다. 또한 12명의 환자를 대상으로 실시한 Rectum dose의 측정치는 computer계산치보다 평균 8%로 낮게 나타났다.