• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.283-290
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• 2007

A bi-modal tram has been developed to offer an advanced transportation service compared with existing vehicles. The All-Wheel-Steering system is applied to the bi-modal tram to satisfy the required steering performance because the bi-modal tram has extended length and articulated mechanism. An ECU for the steering system is essential to steer wheels on 2nd and 3rd axles by the specific AWS algorithm with the prescribed driving condition. The Hardware-In-the-Loop Simulation(HILS) system is planned for the purpose of evaluating the steering system of the bi-modal tram. There are kinematic links with the hydraulic actuator to steer wheels on each 2nd and 3rd axles and also same steering mechanism as the actual vehicle is in the HILS system. Controlling the movement of hydraulic actuator which reflects the lateral steering reaction force on each wheel is the key to realize the HILS system, but the reaction force is continuously changed according to various driving conditions. Therefore, the simulation through the multi-body dynamics model is used to obtain the required forces.

• 한국소음진동공학회논문집
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• 제21권4호
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• pp.333-338
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• 2011

This paper describes the design process of floor damping material optimization to reduce structure borne noise. This process uses finite element analysis(FEA) along with experimental techniques to complement each other. The objective of this approach was to develop an optimized damping material application layout and thickness at the initial design stage. The first step is to find the sensitivity areas of vehicle body without damping material applied using FEA. In order to determine the high vibration areas of the floor panel, the velocity was measured using a scanning laser vibrometer from 20 Hz to 300 Hz. To excite the floor panel vibration, shaker was placed at the front suspension attachment point. The second step is the optimization process to determine the light weight solution of damping material. The design guideline of damping material was suggested that the lightweight solution was verified using test result of road noise. Design engineer could efficiently decide the design variable of damping material using parameter analysis results in early design stage.

• 한국임상수의학회지
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• 제32권1호
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• pp.56-61
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• 2015

The object of this study was to find out the immunomodulatory effects of Ginger Aqueous extracts, as compared with that of ${\beta}$-glucan well-known an immune modulator, on the cyclophosphamide (CPA) induced immunosuppress mice. To induce immunosuppress, 150 and 110 mg/kg of CPA were dissolved in saline and injected intraperitoneally at 3 or 1 day before start of test article administration, respectively. ${\beta}$-glucan or gingers (125, 250, 500 mg/kg) were dosed, 4 times at 12-hr intervals starting 24hrs after last CPA-treatment. Distilled water was used as a vehicle and each groups were used 10 mice. As results of twice intraperitoneal CPA treatment, decreases in the body weight and gain, weight of thymus, spleen. However these CPA-induced immunosuppress changes were inhibited by treatment of three different dosages of ginger or ${\beta}$-glucan as compared with CPA control. Similar favorable inhibitory activities on weight and histopathological change of spleen and thymus induced CPA treatment were detected between ${\beta}$-glucan and ginger 250 mg/kg treated groups.

• 한국환경보건학회지
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• 제35권4호
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• pp.259-268
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• 2009

This study was carried out to investigate the protective effect of Red Ginseng Saponins on 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) induced toxicities in guinea pigs ($200{\pm}10$ g). Normal control (NC) group guinea pigs ($200{\pm}10$ g) received vehicle and saline, while the TCDD-treated (TT) group was given water-extract (WE), saponin fraction (SF) and non-saponin fraction (NSF). Korean red ginseng fractions were administered from 1 week before TCDD-exposure for 4 weeks. Body weight loss and deteriorated clinical parameters related to sugar metabolism and liver function such as lipase and AST, respectively, these were significantly reduced by both saponin and non-saponin fractions. However, increase of lipase was attenuated by the saponin fraction in a dose-dependent manner. Only AST was affected by the saponin fraction. The results suggest that saponins are active substances in the Korean red ginseng water extract against TCDD induced toxicities in Guinea pigs.

• 한국공작기계학회논문집
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• 제15권3호
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• pp.120-126
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• 2006

In this paper, we investigated the characteristics of fatigue fracture on TB(Tailored Blank) weldment by comparing the fatigue crack propagation characteristics of base metal with those of TB welded sheet used for vehicle body panels. We also investigated the influence of center crack on the fatigue characteristic of laser weld sheet of same thickness. We conducted an experiment on fatigue crack propagation on the base metal specimen of 1.2mm thickness of cold-rolled metal sheet(SPCSD) and 2.0mm thickness of hot-rolled metal sheet(SAPH440) and 1.2+2.0mm TB specimen. We also made an experiment on fatigue crack propagation on 2.0+2.0mm and 1.2+1.2mm thickness TB specimen which had center crack. The characteristics of fatigue crack growth on the base metal were different from those on 1.2+2.0mm thickness TB specimen. The fatigue crack growth rate of the TB welded specimens is slower in low stress intensity factor range$({\Delta}K)$ region and faster in high ${\Delta}K$ region than that of the base metal specimens.

• 한국기계가공학회지
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• 제18권12호
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• pp.104-110
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• 2019

A nanosatellite designed by the Korea Microgravity Science Laboratory (KMSL) is currently under development. The KMSL nanosatellite is designed to perform two different scientific missions in space. To successfully complete missions, a variety of tests must be conducted to verify the performance of the designed satellite before launch. As part of the qualification test campaign, the KMSL nanosatellite underwent high level vibrational tests (to comply with Falcon 9 qualification level) to demonstrate the integrity of the system. The purpose of this study is to demonstrate that the primary structure and all electronic and mechanical components can withstand the vibrations and the loads experienced during the launch period. To this end, the KMSL nanosatellite was exposed to static and dynamic loads and various types of vibrations that are inevitably produced during the space vehicle launch period. The vibration test results clearly demonstrated that all avionics and mechanical components can withstand the vibrations and the loads applied to the KMSL nanosatellite's body through a Pico-satellite Orbital Deployer (POD).

• 한국자동차공학회논문집
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• 제22권3호
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• pp.234-240
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• 2014

Driving-related injuries associated with elderly drivers are on the rise, although the overall rate of driving-related injuries has decreased. To determine the causes of this trend, we researched existing vehicle systems that use different sensors and signals to promote safe driving. We found that although the systems alert drivers to potential collisions and assist them in finding a location easily, they were created by people who rarely use the systems in their daily lives. For the most part, they're not created by people with driving difficulties caused by health problems, which in turn often afflict the elderly. To address this issue, we analyzed the drawbacks of the current systems and used a focus group of people with body conditions that have declined due to age to discover the problems they encounter while driving. With the focus group, we used diverse research activities, such as observation and interview to demonstrate how new system concepts could be developed for the elderly. Finally, we propose that adequate system concepts for the elderly would improve driving safety and provide a more enjoyable driving environment for this population.

• 대한교통학회지
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• 제25권4호
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• pp.69-77
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• 2007

본 연구에서는 보행자-차량 충돌사고 분석을 위한 국내외 사고재현모형을 비교하였다. 충돌 후 보행자의 전도거리를 종속변수로, 차량의 충돌속도를 독립변수로 하는 모형을 비교하였으며, 수집된 총 432건의 사고 자료 중 신뢰성 있는 전도거리와 충돌속도 자료의 확보가 가능한 49건을 선정하여 절대평균백분위오차를 산출 후 비교하였다. 또한 전도거리에 영향을 새로운 변수의 도출을 위해 차량의 전면부 형상을 조사하고 이를 변수화하여 모형 구축에 반영하였다. 분석결과 차량의 범퍼높이가 다른 변수에 비해 전도거리에 큰 영향을 미치는 것으로 나타났다. 향후 연구에서는 보다 폭넓고 많은 데이터 수집 및 분석을 통하여 신뢰성을 높은 모형개발이 이루어져야 할 것이다.

• 한국정밀공학회지
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• 제28권10호
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• pp.1166-1173
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• 2011

There have been many researches about SUGV (Small Unmanned Ground Vehicle) mechanism regarding off-road mobility and obstacle negotiation. This paper introduces an analysis of geometry parameters to enhance the vertical obstacle negotiation ability for the SUGV. Moreover, this paper proposes an anti-shock structure analysis of wheels to protect the main body of the SUGV when it falls off a vertical obstacle. Major system geometry parameters will be determined under certain constraints. The constraints and optimization problem for maximizing the ability of vertical obstacle negotiation will be presented and discussed. Dynamic simulation results and experiments with manufactured platform will also be presented to validate the analysis. Several types of wheel materials and structures will be compared to determine the best anti-shock wheel design through FEM (Finite Element Method) simulations.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.824-830
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• 2003

The Power Flow Finite Element Method(PFFEM) offers very promising results in predicting the vibration responses of system structures, and the first PFFEM software, PFADS has been developed in Seoul National University for the vibration predictions and analysis of coupled system structures in medium-to-high frequency ranges. PFFEM is numerical method which solves energy governing equation using finite element technique for complicated structures where the exact solutions are not available. Through the upgrades, the current version PFADS R3 could cover the general beam and plate structures including various kinds of beam-plate rigid joints, spring-damper connection and rigid body connection within beam and plate in addition. This software is composed of three parts; translator, model converter and solver. The translator makes its own FE-model from bulk data of commercial FE software, and the model converter is used to convert FE-model to PFFE-model automatically. The solver calculates vibrational energy density and intensity for PFFE-model by solving global matrix equations of PFFEM. For the applications of PFADS R3, two vehicle models and a container model are examined with respect to major parameters, and reliable results are obtained.