• 한국철도학회논문집
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• 제4권3호
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• pp.94-101
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• 2001

One of the best methods to evaluate crashworthiness of a full rake trainset is to analyse 1-dimensional dynamic model using dampers, nonlinear springs and bars, and masses. In this study, the crashworthiness of KHST has been evaluated by analysing a nonlinear dynamic model made up of springs/bars-dampers-masses. The numerical results show that the KHST can absorb more kinetic energy at lower impact forces and lower accelerations in case of heavy collisions, if compared with KTX. Also, the KHST can be protected from any damage in its car-body and electric components except the energy absorbing tube in case of light collisions, like train-to-train accidents at speed under 8 kph. On the other hand, the KTX may be more damaged in the light collisions because there is no energy absorbing tube.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.645-651
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• 2000

In this paper, numerically evaluated is the regulations for crashworthy design of the Korean standard urban train suggested by KRRI. The 4-car consist of K-EMU(Korean Electric Multiple Unit) train developed in recent is analyzed under various collision conditions such as normal coupling, heavy shunt, light and heavy collisions. The collision conditions are assumed as K-EMU collides against another stationary one at 5 kph, 10 kph, 25 kph and 32 kph. According to the numerical results and bibliographical study, it is necessary that the regulations by KRRI be complemented from crashworthy point of view. Furthermore, the K-EMU train is recommended to adopt a new coupler with an additional energy absorber or a mechanical fuse.

• 대한조선학회논문집
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• 제46권4호
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• pp.398-408
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• 2009

Crude oil carriers or product oil carriers are confronted with sea pollution due to hull damage from various accidents. To reduce the oil spillage of tankers, IMO(International Maritime Organization) and OPA 90(Oil Pollution Act 1990) adopted the hull structures of double skin type. In this study, oil spillage test of the double skin tanker with 1/100 scaled model was carried out under damaged condition due to collision and grounding accidents. A new structural type of oil tanker was also tested with pipe and valve system arranged in double side and single bottom hulls. Their results were compared with that of conventional type double hull on the view point of ship safety and oil spillage.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.241-257
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• 2020

The rapid proliferation of oil/gas drilling and wind turbine installations with jack-up rig-formed structures increases structural safety requirements, due to the greater risks of operational collisions during use of these structures. Therefore, current industrial practices and regulations have tended to increase the required accidental collision design loads (impact energies) for jack-up rigs. However, the existing simplified design approach tends to be limited to the design and prediction of local members due to the difficulty in applying the increased uniform impact energy to a brace member without regard for the member's position. It is therefore necessary to define accidental load estimation in terms of a reasonable collision scenario and its application to the structural response analysis. We found by a collision probabilistic approach that the kinetic energy ranged from a minimum of 9 MJ to a maximum 1049 MJ. Only 6% of these values are less than the 35 MJ recommendation of DNV-GL (2013). This study assumed and applied a representative design load of 196.2 MN for an impact load of 20,000 tons. Based on this design load, the detailed design of a leg structure was numerically verified via an FE analysis comprising three categories: linear analysis, buckling analysis and progressive collapse analysis. Based on the numerical results from this analysis, it was possible to predict the collapse mode and position of each member in relation to the collision load. This study provided a collision strength assessment between attendant vessels and a jack-up rig based on probabilistic collision scenarios and nonlinear structural analysis. The numerical results of this study also afforded reasonable evaluation criteria and specific evaluation procedures.

• 정보처리학회논문지C
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• 제11C권6호
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• pp.851-862
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• 2004

RFID(Radio Frequency IDentification) 기술은 RF 신호를 사용하여 물품에 부착된 전자태그를 식별하는 비접촉 기술이다. 식별 영역 내에 다수의 태그가 존재한 경우에 요구되는 다중 태그 식별 문제는 RFID 기술 중에서도 핵심 이슈이며 이 문제는 충돌방지 알고리즘을 통하여 해결할 수 있다. 하지만 기존 알고리즘들은 구현의 복잡성과 낮은 성능이 문제로 제기되고 있다. 본 논문에서는 이러한 문제를 해결할 수 있는 트리 기반 메모리래스 충돌방지 알고리즘인 충돌 추적(Collision Tracking) 트리 알고리즘을 제안하고 성능평가 결과를 제시한다. 성능평가 결과 제안하는 알고리즘이 초당 749개의 태그를 식별하면서 기존 트리 기반 메모리래스 알고리즘인 트리-워킹 알고리즘과 쿼리 트리 알고리즘에 비해 각각 약 49배와 2.4배의 성능향상을 확인할 수 있었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.217-222
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• 2001

The best method to evaluate crashworthiness of a trainset as a whole is to analyse one dimensional dynamic model composed of nonlinear dampers, springs and bars, and masses. In this study, crashworthiness of KHST was evaluated by analysing a nonlinear spring/bar-damper-mass model. The numerical results show that the KHST can easily absorb kinetic energy at lower impact force and acceleration in a heavy collision, when compared with KTX. Also, the KHST can be protected from any damage in its carbody and components except the prepared energy absorbing tube in a light collision, like a traint-to-train accident at speed under 8 kph. However, the KTX can be much damaged in the a light collision because there is no energy absorbing tube.

• 한국대기환경학회지
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• 제15권1호
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• pp.1-11
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• 1999

In this work, a theoretical model has been formulated which allows the study of the scavenging efficiencies of aerosol particles by the rain drops. Aerosol particles are scavenged by the simultaneous brownian diffusion, interception and inertial impaction force. In addition the calculations based on the collision efficiency model are carried out for the collision of aerosol particles with diameter range 0.01~30 $mu extrm{m}$ and rain drops with diameter 0.02$\times$$2^{n/3}$(n=1, 2, …, 17)cm. The results indicate that: (1) the below-cloud scavenging affects mainly the coarse particles (＞3 ${\mu}{\textrm}{m}$), the fine particles remaining almost unchanged; (2) the scavenging efficiencies by below-cloud in the heavy rain (rain intensity, 10 mm/hr) surpass the efficiency found in the drizzle rain (rain intensity, 1 mm/hr).

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.772-779
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• 2008

Through this study, standard design guidelines for the high speed EMU have been derived to meet the crashworthiness requirements of the Korean rollingstock safety regulation. The crashworthiness regulation requires some performance requirements for two heavy collision accident scenarios; a train-to-train collision at the relative speed of 36 kph, and a collision against a standard deformable obstacle of 15 ton at 110 kph. The complete train set will be composed of 2TC-6M with 13 ton axle load, different from KTX with the power car of 17 ton axle load. Using theoretical and numerical analyses, some crashworthy design guidelines were derived in terms of mean crush forces and energy absorptions for main crushable structures and devices. The derived design guidelines were evaluated and improved using one dimensional spring-mass dynamic simulations. It is shown from the simulation results that the suggested design guidelines can easily satisfy the domestic crashworthiness requirements.

• 로봇학회논문지
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• 제1권1호
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• pp.46-57
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• 2006

It is well known that mathematical solutions for multi-agent planning problems are very difficult to obtain due to the complexity of mutual interactions among multi-agent. Most of the past research results thus are based on the probabilistic completeness. However, the practicality and effectiveness of the solution from the probabilistic completeness is significantly reduced by heavy computational burden. In this paper, we propose a practically applicable solution technique for multi-agent planning problems, which assures a reasonable computation time and a real world application for more than 3 multi-agents for the case of general shaped paths in agent movement. First, to reduce the computation time, a collision map is utilized for detecting potential collisions and obtaining collision-free solutions for multi-agents. Second, to minimize the maximum of multi-agent task execution time, a method is developed for selecting an optimal priority order. Simulations are finally provided for more than 20 agents to emphasize the effectiveness of the proposed interactive approach to multi-agent planning problems.

• Bulletin of the Korean Chemical Society
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• 제16권2호
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• pp.101-104
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• 1995

In an attempt to understand the nature of hyperthermal ion-surface collisions, noble gas ion beams (He+, Ne+, Ar+, and Xe+) are scattered from a Si(100) surface for collision energies of 20-300 eV and for 45°incidence angle. The scattered ions are mass-analyzed using a quadrupole mass spectrometer and their kinetic energy is measured in a time-of-flight mode. The scattering event for He+ and Ne+ can be approximated as a sequence of quasi-binary collisions with individual Si atoms for high collision energies (Ei > 100 eV), but it becomes of a many-body nature for lower energies, Ar+ and Xe+ ions undergo mutliple large impact parameter collisions with the surface atoms. The effective mass of a surface that these heavy ions experience during the collision increases drastically for low beam energies.