• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8966-8976
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• 2015

Unshielded posts on roadside are a critical hazard to the safety of impact vehicle to the posts. A crashworthy post is developed. In the first phase, it dissipates the impact energy by the linear momentum conservation principle while the plastic impact between the post and vehicle takes place, then, the second phase dissipation follows by the deformation of the energy absorbing modules embedded in the guide trough of the foundation. Simulations of impacts to a rigidly connected post and crashworthy post were made using LS-DYNA program, which demonstrated the danger of unshielded rigidly connected post and the effectiveness of the proposed crashworthy post to the 0.9ton-80km/h impact.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.5
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• pp.329-339
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• 2017

Impingement jets have been applied in a wide variety of fields as they provide significantly high heat transfer on the impingement-jet stagnation zone. However, the crossflow in an impingement chamber developed by spent wall jets can disrupt and deflect the downstream jets in the array, leading to a decrease in the cooling performance of an array of impingement jets. A numerical analysis is made of the fluid flow and heat transfer characteristics in a corrugated structure that traps the spent air in the corrugations between impingement jets and reduces crossflow effects on downstream jets. All computations are performed by considering a three-dimensional, steady, and incompressible flow by using the ANSYS-CFX 15.0 code. The effects of the configuration parameters of the corrugated structure on crossflow reduction of the array of impingement jets are presented and discussed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.33-41
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• 2008

As RFID technology is developing and increasingly being used in many applications, the implementation is changing from single reader to multiple readers even dense readers. Since the number of readers is increasing, there are more collisions between readers and much interference between readers and tags. Therefore, to avoid interference or collision, many algorithms have being proposed, such as Gen2 dense mode, LBT(listen before talk), TDMA based method. In this paper, we propose a null frame algorithm, which calculates the collision probability in frame slotted aloha scheme and use this information to avoid the possible collisions. Comparing with conventional scheme, our proposed algorithm has some advantages in terms of reader collision number and required frame numbers.

• Tunnel and Underground Space
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• v.27 no.5
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• pp.282-294
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• 2017

This study analyzed the development status and applications of collision avoidance systems for mine safety management. The definitions of collision avoidance system used in Australia and USA were compared. Sensing technologies utilized in the collision avoidance systems were reviewed. In addition, several collision avoidance systems developed in oversea mining company, such as $MineAlert^{TM}$ Collision Awareness System, Cat $MineStar^{TM}$, and Intelligent Proximity Detection, were reviewed. In the domestic mining industry, no collision avoidance system was used. However, similar systems were utilized in the construction and railroad industry. Collision avoidance system can prevent unexpected collision accident and thus improve worker's safety in mine. Therefore, it is necessary to analyze and apply sensors and system appropriate for the domestic mining environment via review of overseas collision avoidance system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5963-5967
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• 2014

Reducing the impact of collisions of cars is a major issue for reducing the injury and death of passengers. According to the statistical data of the Road Traffic Authority, the deaths from side collision accidents caused by the collision of passenger cars is greater than the deaths from head-on collision accidents. To accommodate this, vehicle designers have added a reinforcing material called the impact frame and impact beam on the inside of the door. Many experiments are needed to develop the door impact beam. These reinforcements to develop a collision experiment is essential. Collision experiments are costly and time consuming. This study used a drop Impactor to obtain the impulse and a strain experimental device was developed for this purpose. The economic costs were reduced and the ideal experiment device configuration was determined. A comparison of the experimental results with numerical value analysis revealed $3.5{\tiimes}10-3sec$ strain ranging from $3.49{\tiimes}10-3$ to $3.99{\tiimes}10-3$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.123-134
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• 2006

In this study ship collision risk analysis is performed to determine the design vessel for collision impact analysis of the maritime bridge. Method II which is a probability based analysis procedure is used to select the design vessel for collision impact from the risk analysis results. The analysis procedure, an iterative process in which a computed annual frequency of collapse(AF) is compared to the acceptance criterion, includes allocation method of acceptance criterion of annual frequency of bridge component collapse. The AF allocation by weights seems to be more reasonable than the pylon concentration allocation method because this AF allocation takes the design parameter characteristics quantitatively into consideration although the pylon concentration allocation method brings more economical results when the overestimated design collision strength of piers compared to the strength of pylon is moderately modified. From the assessment of ship collision risk for each bridge pier exposed to ship collision, a representative design vessel for all bridge components is selected. The design vessel size varies much from each other in the same bridge structure depending upon the vessel traffic characteristics.

• Journal of the Korean Chemical Society
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• v.42 no.3
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• pp.297-301
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• 1998

Linkage positions in oligosaccharides may be obtained by FAB CAD MS/MS (Fast Atom Bombardment Collision Activated Dissociation Mass Spectrometry/Mass Spectrometry). Acetylated derivatives of the linkage-isomeric trisaccharides exhibited more useful product ion patterns than the free trisaccharides and provided specific fragmentation patterns according to linkage positions. The reason for the useful linkage dependent spectra patterns of acetylated forms is related to the ability of each linkage in the oligosaccharides to absorb different levels of collision energy and rotational freedom of the individual glycosidic linkage.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.290-293
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• 2014

하인리히 법칙에 따르면, 하나의 대형사고는 다수의 경미한 사고나 수많은 근접한 위험상황이 발생한 위치에서 발생할 확률이 높다. 해상교통상황에서도 양 선박이 충돌 위험이 있는 상황, 즉 근접사고 상황은 해상교통관련 대형 사고를 예방하는 관점에서 중요하다. 하지만, 아직까지 이러한 근접사고 자료는 VTS데이터 접근에 어려움, 관련 전문 기법 부족 등으로 수집 분석하는데 어려움이 있었다. 이에 본 연구에서는 해상교통 근접사고를 조우하는 선박간에 시공간적으로 충돌에 근접한 상황들이 발생하여 충돌의 위험이 일정한 값 이상으로 높아진 상황으로 정의하고, 2013년도 완도VTS 관제해역 해상교통 항적데이터를 적용하여 근접사고 통계를 분석하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.120-122
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• 2014

선박의 조타기 작동 신호를 AIS를 통하여 전달함으로써 상대선박의 변침의도를 신속히 파악하여 충돌위험을 피할 수 있는 선회조기감지시스템을 구현하고 실선실험을 통하여 그 실효성을 검증하였다. 또한, 실선실험을 통해 선박의 타각정보가 AIS를 통해 송 수신이 가능하다는 것을 확인하였으며, ECDIS에 표시된 타각정보는 주변선박의 충돌회피에 크게 기여할 것으로 판단된다. 선회조기감지시스템은 선박의 안전운항을 위한 정보 제공의 필요성, 선박 통항량 증가 및 고속화 등으로 인한 위험성 증대로 VTS관제의 역할이 더욱 중요시 되고 있는 상황에서 선박의 조타각이 표시된 해당 시스템을 활용할 경우 변침상황을 보다 신속히 파악할 수 있으므로 관제가 보다 쉬워질 것으로 예상된다. 또한, 선박의 침몰이나 VDR의 소실로 인한 해양사고 분석의 어려움도 AIS를 통한 조타신호가 저장된 해양안전종합정보시스템(GICOMS)의 분석을 통해 다소 해소될 것으로 판단된다.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.60-68
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• 1996

디젤 엔진의 분사연료를 연소실 내부에 마련된 작은 돌출부에 충돌시켜 액적을 작게 부수고 연료가 연소실 내부에 고루 분포할 수 있도록 하여 여러 가 지 엔진성능향상을 도모한 새로운 디젤 연소실 시스템이 최근 제시되고 있다. 이들 시스템은 피스톤 내부 혹은 엔진헤드 부위에 분사연료 충돌부를 두고 있는데, 여기에서는 이 새로운 시스템 개발에 있어 고려되어야 할 몇 가지 중요 요인들에 중점을 두어 분석하였다. 결과로서 분사압력, 사노즐크기, 주위공기 온도와 압력의 변화가 분무 평균입경과 분무연료의 분포에 미치는 영향을 제시하였다.