• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.322-325
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• 2005

TTX(Tilting Train eXpress) is being designed for improving the speed of conventional railway. The purpose of this study is to evaluate energy absorbing capacity and driver's survivability for a design candidate of the front end structure of TTX. A FE model with honeycomb block, under frame, and body frame is generated for crash simulation. Based on a level-crossing accident scenario, numerical simulation is performed using LS-DYNA. The results of crash analysis show that strength improvement of the current front end structure design candidate is needed to ensure driver safety.

• 자동차안전학회지
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• 제6권2호
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• pp.5-11
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• 2014

Front side member of the front impacted vehicle plays a key role in minimizing the impacting load transferred to the compartment. To perform that required function, axial collapse should be dominant during side member crashing and, prior to designing side member, it is crucial to minimize bending moment occurred at the front end. In this study, for FE model of a SUV front body, front impact analyses were carried to find out bumper stay design which effectively develope axial collapse in the side member. As a previous work, the thickness of side member reinforcement were changed. Next, the inner thickness of bumper stay was increased. Also, the bead shape and location were modified. Final front body model showed much more axial collapsed mode and enhanced crash performance. In addition, a stay of octagon section was adopted and that model exhibited distinctive increase in impact energy absorption.

• 한국인터넷방송통신학회논문지
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• 제23권1호
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• pp.123-129
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• 2023

본 논문에서는 Ka대역 소형 레이다용 주파수합성 MMIC(FS MMIC)와 수신 MMIC를 개발하고 개발된 MMIC를 기반으로 소형화 된 Ka대역 주파수합성기와 수신기를 개발하였다. FS MMIC와 기저대역 신호를 수신하는 WR(wireless-receiver) MMIC는 65 nm CMOS 공정으로 제작하였고, Ka대역 신호를 수신하는 FE(front-end) MMIC는 150 nm GaN 공정으로 제작하였다. FS MMIC를 바탕으로 개발된 주파수합성기의 출력신호를 이용하여 Ka 대역 신호에 대한 주파수선형변조 파형과 펄스 파형을 측정하고 송신 파형 생성 가능성을 확인하였다. FE MMIC 및 WR MMIC로 구성된 수신기의 성능은 이득 80 dB 이상, 잡음지수 6 dB 이하, OP1dB 10 dBm 이상으로 측정되었다. 측정결과를 통해 본 논문에서 개발된 주파수합성기, 수신기는 Ka 대역 소형 레이다에 적용 가능한 것으로 판단된다.

• 한국자동차공학회논문집
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• 제20권3호
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• pp.67-76
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• 2012

In this paper, collision analysis of the full rake for the Next Generation High-speed EMU is conducted using a 3D/1D hybrid model, which combines 3-dimensional (3D) front-end structure of finite element model and 1-dimensional (1D) multi-body dynamics model in order to analyze train collision with a standard 3D deformable obstacle. The crush forces, passengers' accelerations and energy absorptions of a full rake train can be easily obtained through a simulation of a 1D dynamics model composed of nonlinear springs, dampers and masses. Also the obtained simulation results are very similar to those of a 3D model if an overriding behavior does not occur during collision. The standard obstacle in TSI regulation has been changed from a rigid body to a deformable body, and therefore 3D collision simulations should be conducted because their simulation results depends on the front-end structure of a train. According to the obstacle collision analysis of this study, the obstacle collides with the driver's upper structure after overriding over the front-end module. The 3D/1D hybrid model is effective to evaluate a main energy-absorbing module that is frequently changed during design process and reduce the need time of the modeling and analysis when compared to a 3D full car body.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2000년도 봄 학술발표논문집 Vol.27 No.1 (A)
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• pp.660-662
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• 2000

오늘날 네트웍의 발달로 인하여 사용자가 원하는 영상매체를 실시간으로 요구하는 멀티미디어 서비스에 대한 사용자의 요구가 날로 증가하고 있다. 때문에 영상매체를 제공하는 서버는 여러 사용자들이 동시에 접속하였을 때 서비스를 제공 할 수 있는 능력을 가져야 한다. 본 논문에서는 멀티미디어 서비스를 위한 VOD(Video-On-Demand)시스템을 설계 및 구현한다. VOD 시스템은 미디어를 분석하여 BES(Back-End-Server)에 저장하는 영화 관리자(Movie Manager), 분산 저장된 데이터를 읽어 들여 사용자나 연결된 FES(Front-End Server)로 보내는 BES, 사용자에게 미디어 데이트를 전송하는 FES와 전송된 데이트를 받아서 재생하는 클라이언트(Client)를 구성된다. 또한 다수의 서버를 연결하기 위하여 SCI(Scalabel Coherent Interface)를 이용한 효율적인 메시지 전송방법을 구현한다.

• 한국자동차공학회논문집
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• 제21권5호
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• pp.97-103
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• 2013

Crash performance of the straight member was studied by FE analysis. One end of model was fixed and the other end was impacted by 1,000kg rigid mass with velocity of 16.0m/sec. The maximum and mean load were discussed to compare crash performance. The members with various section shapes were analyzed and the flange location was changed. Also, spot weld points were added in the initial buckling region to investigate its effect. Final rectangular section model which has flanges at the center and reinforcement in initial buckling region showed high enhancement in crash performance.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.326-330
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• 2007

Bumper back beam is one of the essential structural components of front-end module. It should be designed to withstand a minor bump in low-speed collision, 2.5 mph crash test for example. And weight reduction is always important problem in the design of almost all the parts in car for energy saving. So, the key issues in shape design of a bumper are weight reduction and the performance in 2.5mph crash test. In this study, a light weight and high performance bumper back beam model was developed using analytical approach based on mechanics and FE simulation together.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.377-384
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• 1998

The crushable front part of the conventional TGV is composed of 3 energy absorption zones; retractable coupler, protective headstock and honeycomb structure. This frontal part must absorb about 80% of the energy that should be done in a cra shworthy design. The conventional TGV can absorb 2MJ impact energy by the frontal end, but 5MJ is the design target for energy absorption in the next generation TGV. To accomplish this design goal, a new concept of design is necessary for energy absorbing components. In this paper, the design concept of the tube expansion energy absorber will be proposed and analyzed. The crash analysis of the energy absorber are performed by comparing the value of the theoretical equation wi th the simulation calculated from the commercial nonlinear FE-Code ‘PAM-CRASH’ S/W.

• 대한화학회지
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• 제3권1호
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• pp.23-27
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• 1954

The relation between the height of ascending solvents and its velocity were studied with strips of Toyo No. 50 filter paper. The filter paper strip of 3cm width and cat 30 cm length is hooked down or fixed between two sheets of glass plates inside a cylinder containing the solvent, in which the lower end of the strip is dipped. As the solvents, acetone, hydrochloric acid, water or mixtures of these are used. For short time intervals, Ostwald's folmula $h = Kt^n$ was found to be most suitable to express the relation between the height of the solvent front, h, and time, t. For longer time intervals, results will be discussed in the next paper. The mean values of the constant m in the above formula for pure acetone and pure water were 0.44 and 0.485, respectively, and that of K were 0.05 and 2.4, respectively. The time interval whose the above formula applies, for each solvent was 2 hours for the former, and a half hour for the later, respectively. The movement of solutes, such as $Cu^{++}$ and $Fe^{++}$ showed that the Rf values of solutes become constant values after a long periods; e.g., ca. 6 hours with 10N-HCl-Acetone (1 : 9) solvent.

• Journal of Welding and Joining
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• 제33권3호
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• pp.62-67
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• 2015

A very large shell-structure built in shipyards like ship hulls or offshore structures are joined by welding through full process. As the welding contains a high thermal cycle at a local area, the welded structures should be distorted unavoidably. Because a distorted ship block should be revised to the designed value before the next stage, the ability to predict and to control the weld distortion is an accuracy level of the yard itself. Despite the ship block size, several present thermal distortion methodologies can deal those sizes, but it is a different story to deal full ship size model. Even a fully constructed ship hull not remaining any welding can have an accuracy issue like outfitting installation problems. Any present thermal distortion methodology cannot accept this size for its recommended element size and the number. The ordinary welding breadth at erection stage is about 20~40 mm. It can hardly be a good choice to make finite element model of these sizes considering human effort and computational environment. The finite element model for structure analysis of a ship hull is prepared at front-end engineering design stage which is the first process of the project. The element size of the model is as fine as the longitudinal space, and it is not proper to obtain a weld distortion at the erection stage. In this study, a methodology is suggested that a weldment can be shrunk at original place instead of using structural finite element model. We cut the original shell elements at erection weld-line and put truss elements between the edges of cut elements for weld shrinkage. Additional truss elements are used to facsimile transverse weld shrinkage which cannot be from the weld-line truss element shrink. They attach to weld-line truss element like twigs from barks. The capacity of developed elements is verified through an accuracy check of erection process of a container vessel at the apt. hull. It can be a useful tool for verifying a centering accuracy after renew and for block-separating planning considering accuracy.