• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.353-357
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• 2007

We have been setting up experiments on propagation of shock waves generated by the pulsed laser ablation. One side of a thin metal foil is subjected to laser ablation as a shock wave propagates through the foil. The shock wave, which penetrates through the foil is reflected by an acoustic impedance which causes the metal foil to high-strain rate deform. This short time physics is captured on an ICCD camera. The focus of our research is applying shock wave and deformation of the thin foil from the ablation to accelerating micro-particles to a very high speed.

• Journal of Korean Society of Transportation
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• v.28 no.1
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• pp.25-38
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• 2010

In this study, the real on-road driving data were analyzed to draw the various characteristics related to idling of vehicles. The results revealed that the average idling time of a city bus corresponds to 30.9% of the total daily driving time. Among this, for about 21.6% of the total daily driving time, it is available that an engine can be halted while the vehicle stops. It is a daytime when the portion of time, for which idling stop is available, is peak. Due to idling stop, an increase of turnaround was not found throughout this analysis. When a city bus stops at a traffic right, idling periods were long enough to execute the idling stop, during which an engine halts. Whereas, during the idling time for bus stops, the idling periods were not so long enough to execute idling stop. Deceleration periods among the total turnarounds of a city bus occupies about 24.7%, during which, for about 30%, a deceleration maintains for more than four seconds. Thus, using the energy during deceleration period, which then can be recovered from braking energy, it was also found that a hybrid system can be effectively implemented to a city bus.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.878-886
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• 2009

This paper proposes an optimal algorithm for generating a train speed profile giving optimal energy efficiency based on GA (Genetic Algorithm) and shows its effectiveness with simulations. After simplifying the train operation mode to a maximum traction, a coasting and a maximum breaking, adjusting the coasting point to minimize the train consuming energy is the basic scheme. Satisfying the two constraints, running distance and running time between two stations, a coasting point is determined by GA with a fitness function consisting of a target running time. Simulation results have shown that multiple coasting points could exist satisfying both of the two constraints. After figuring out consumed energies according to the multiple coasting points, an optimal train speed profile with a coasting point giving the smallest consumed energy has been selected. Simulation blocks for the train performance simulation and GA have been designed with the Simulink.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.301-303
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• 2015

디지털 운행기록장치는 대한민국의 경우 2011년부터 상용차에 대해 법령으로 장착이 의무화되었다. 이 장치는 자동차의 속도, 주행거리, 브레이크 상태, GPS 위지청보 등을 수집하는 기록 장치로서 이를 통해 수집된 정보로 운전 형태를 파악하고 분석해준다. 그러나 초기 장치 구입비용과 전송 방식에 따른 월별 통신서비스 비용 때문에 일반 운전자의 사용이 제한된다. 따라서 본 연구는 일반 운전자도 위험운전행동을 분석하고 파악하여, 결과를 제공하는 스마트폰 어플리케이션의 설계 및 구현을 목적으로 한다. ECU(Electronic Control Unit)에서 얻을 수 있는 주행 데이터(가속 제동, 속도, 운전 시간 등)를 OBD-II(On-Board Diagnostic version II) Scanner를 통해 수집한다. 이 정보를 바탕으로 위험운전평가 알고리즘을 이용하여 실시간 분석한다. 상기 알고리즘은 대한민국의 교통안전공단에서 제공하는 위험운전(11종)에 대한 정의를 바탕으로 한다. 이를 통해 분석된 결과는 실시간으로 사용자에게 제공되며, SQLite를 이용하여 DB에 저장되고 통신사의 이동통신(3G,4G) 혹은 Wifi의 네트워크를 이용하여 연계 서버에 전송된다. 이 위험 운전 분석 어플리케이션을 통해 운전자들의 안전 운전을 유도하고자하며, 추후 운전습관 연계 보험의 도입에 따라 합리적이고 공정한 데이터를 제공하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.3
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• pp.1-8
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• 2004

This paper proposes an LQ-PID controller to reduce errors occurring between input and output speeds in braking or emergency braking and to solve delay of speed or the excessive overshoot problems occurring at the speed control of induction motor. The conventional LQ controller is a method that move the poles in locations that satisfy design specifications such as overshoot and settling time etc. by state-feedback. So it may not be able to satisfy the overshoot requirement in case of the existence of zero in the closed loop transfer function. To attack this zero-problem it is presented a new design methodology of LQ-PID controller by introducing an analytic technique to eliminate the effect of zeros on the closed loop transfer function.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.3-13
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• 2013

This paper contains two algorithms proposed for synchronization in OFDM system. The first is having 1 symbol offset while calculating the timing metric, and the second is introduced in new parameter such as Reduction Factor(${\rho}$), Break Constant(${\beta}_k$) and Implant Depth(${\delta}_I$) in order to control the power of CP(Cyclic Prefix) area. Two proposed method are evaluated performance with conventional methode, and than the result of simulation show proposed methods is better than conventional methode while it experience into multipath fading channel.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.269-270
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• 2006

Brake noise is classified according to frequency territory: judder, groan and squeal. Squeal noise of disk brake is a noise and self excited vibration with frequency of $1{\sim}10Khz$ caused by the friction force between the disk and the pad of the automobile. Passengers in a vehicle feel uncomfortable. It causes unstable characteristic to the brake system when you try to stop the vehicle. Thus this study aims to find in which conditions the vehicles are stable during the braking hour and find ways to decrease a squeal noise and the vibration by measuring various factors including squeal noise and self excited vibration between the pad and disk brake system during the braking hour. From the result the countermeasure for a squeal noise and a vibration decrease is established. Also the analyzed data is found to be useful and can be applied to the actual brake model.

• Journal of Auto-vehicle Safety Association
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• v.5 no.2
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• pp.17-23
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• 2013

This paper describes an algorithm for Advanced Emergency Braking(AEB) with tire-road friction coefficient estimation. The AEB is a system to avoid a collision or mitigate a collision impact by decelerating the car automatically when forward collision is imminent. Typical AEB system is operated by Time-to-collision(TTC), which considers only relative velocity and clearance from control vehicle to preceding vehicle. AEB operation by TTC has a limit that tire-road friction coefficient is not considered. In this paper, Tire-road friction coefficient is also considered to achieve more safe operation of AEB. Interacting Multiple Model method(IMM) is used for Tire-road friction coefficient estimation. The AEB algorithm consists of friction coefficient estimator and upper level controller and lower level controller. The numerical simulation has been conducted to demonstrate the control performance of the proposed AEB algorithm. The simulation study has been conducted with a closed-loop driver-controller-vehicle system using using MATLAB-Simulink software and CarSim Vehicle model.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.341-342
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• 2018

Unlike previous studies on the optimum route of the ship operating on th ocean, this study proposed an optimization method for the route planning of the ship operating on the coast. In general, passenger ships on the coast navigate along the waypoints indicated in the authorized route. Therefore this study propose objective function considering the braking power and time to determine the speed between waypoints, and the optimum speed was determined by applying the proposed method to the actual route of the passenger ship between Mokpo and Jeju.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.456-461
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• 2003

기존선 속도 향상 및 병목현상 해소와 안전운행을 위해 국내 철도 현황의 주요 분야를 검토한 후, 국내 17년동안 사용으로 안전성이 검증된 신호기술을 바탕으로 국내 실정에 적합하며, 기존의 ATS 장치를 개선한 정보형 ATS(ATPS)를 개발하여 이를 제시하였다. 본 시스템은 운행 중인 열차의 제동특성을 고려하여 구간별 제한속도를 상향 조정하여 운행 효율을 증가 시킬 수 있다. 또, 안전성과 신뢰성 보장을 위해 Fail-Safe 및 이중계(redundancy)로 제작 하였고, 기존의 차상자와 발진기를 통합함으로써 Q factor를 개선하여 무응동 방지 및 기준 응동시간 비교방식을 통해 오동작을 개선하였다. 그리고, 정보기록 장치를 추가함으로써 이미 기록되어있는 차량정보데이터와 지상정보데이터를 연산하여 운전정보를 제공하고 기록한다. 또한, 이 운전정보는 정보 분석용 PC 및 프로그램에 의해 쉽게 분석, 관리가 가능하다. 무엇보다도 기존 ATS 구간과의 겸용사용으로 영업 운전시 안전한 연속 운행 보장 및 지상설비 개량 없이 안전을 확보할 수 있다. 다양한 종류의 동력차에 설치, 인터페이스 및 지상설비 개량이 용이하다. 향후 틸팅 시스템과 연계하여 틸팅 제어/감시 신호를 제공하는 기능을 갖는다.