• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.2
• /
• pp.175-181
• /
• 2004

Analysis of brake characteristics has progressed rapidly in recent years, as computer techniques have developed. However, there are many problems in predicting braking characteristics, due to the numerous design variables of the brake system. Therefore, a synthetic braking performance analysis is required for all brake system parts such as master cylinder, booster, control valve and split system. In this paper, a program which can analyze braking performance such as force distribution, braking efficiency, pedal force and pedal travel, is presented. The preprocessor of the program helps users prepare input files through a dialog box. An additional postprocessor makes the graph presentation of solved results. Also, a simple example problem is applied to show the usefulness of the presented program.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.10b
• /
• pp.134-137
• /
• 2006

디지털멀티미디어방송(DMB)은 고품질의 방송 영상 및 부가 데이터를 이동 중인 차량내에서나 휴대형 단말에서 수신할 수 있는 이동 멀티미디어 방송 서비스이다. 그러나 현재 국내에서 상용화 되고 있는 지상파와 위성 DMB 서비스는 아직 비디오와 오디오에 기반한 단순한 컨텐츠에 중심을 두고 있어 사용자의 기대치에 미치지 못하고 있는 상황이다. 그리하여 현재처럼 단순히 기존의 오디오와 비디오에 기반한 케이블 TV프로그램을 그대로 옮겨올 것이 아니라, 다양한 미디어 객체들을 추가하여 사용자 인터랙티브한 대화형 멀티미디어 컨텐츠를 지원하고 더 나아가서 사용자와 서비스 제공자와의 인터랙션을 지원하는 양방향 데이터 서비스에 대한 연구가 필요하다. 본 논문에서는 실시간 양방향 대화형 DMB 서비스를 최종목표로 먼저 PC환경에서 뿐만아니라 모바일 환경에서 MPEG-4 컨텐츠의 스트리밍 시스템을 구현함으로써 DMB시스템을 시뮬레이션 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.193-193
• /
• 2004

자기 브레이크(Magnetic Brake)는 기계식 브레이크와 달리 비접촉식으로 제동이 가능하여, 마모 등에 따른 제동 효과의 저감이나 브레이크의 수명 단축을 배제할 수 있어 그 사용 범위가 확장되고 있는 추세이다. 특히 최근에는 영구자석의 발전에 힘입어, 강한 보자력을 갖고 있는 영구자석이 개발됨에 따라 코일 둥의 능동 요소 없이 반영구적으로 효과적인 제동을 발휘 할 수 있다［1］. 자기 브레이크는 고속 이송 또는 회전 시 기계식 브레이크에서 발생되는 점착(adhesion) 현상으로 인한 성능 한계를 극복하기 위하여 개발되어 왔으며, 최근에는 자기 부상 분야와 고속 주행 차량의 마멸에 의한 기계식 브레이크의 성능 감소를 피하기 위해 이용되고 있다.(중략)

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.5
• /
• pp.473-479
• /
• 2009

This paper proposes an efficient method to locate the automated guided vehicle (AGV) into a specific parking position using artificial visual landmark and vision-based algorithm. The landmark has comer features and a HSI color arrangement for robustness against illuminant variation. The landmark is attached to left of a parking spot under a crane. For parking, an AGV detects the landmark with CCD camera fixed to the AGV using Harris comer detector and matching descriptors of the comer features. After detecting the landmark, the AGV tracks the landmark using pyramidal Lucas-Kanade feature tracker and a refinement process. Then, the AGV decreases its speed and aligns its longitudinal position with the center of the landmark. The experiments showed the AGV parked accurately at the parking spot with small standard deviation of error under bright illumination and dark illumination.

• Information and Communications Magazine
• /
• v.29 no.5
• /
• pp.62-70
• /
• 2012

대량의 인명 피해가 발생하는 도심 내 급속 확산형 재난 상황이 전 세계적으로 발생함에 따라, 재난 대응을 위한 응급 운송 및 시뮬레이션 연구에 대한 관심이 증가하고 있다. 본 연구에서는 최근 다양한 방법으로 연구되고 있는 재난 대응 응급 운송 및 시뮬레이션 연구의 동향을 구조적인 내용 분석 기법을 이용하여 정리하였다. 우선, 재난 발생 전/후에 발생하는 응급 운송에 관한 문제들을 분류하고 문제의 특징을 분석하였다. 그리고 응급 자원의 최적할당 및 피해 지역 사람들의 효과적인 이송에 관한 의사 결정을 지원하기 위한 시뮬레이션 연구를 정리하였다. 최종적으로, 이러한 구조적 내용 분석을 바탕으로 자율 적응형 재난 대응 체계 구축을 위한 미래의 연구방향을 제시하였다.

• Tunnel and Underground Space
• /
• v.6 no.1
• /
• pp.57-63
• /
• 1996

The goal of this study is to develop a simulation model of the pollutant dispersion in vehicle tunnels, which can be utilized to optimize the tunnel ventilation system. Contaminant dispersion is modelled using a FDM solution of advective diffusion equation. Taking into consideration the local vehicle emission rates by year, it is user-oriented and its logic is generalized. Therefore, differences in the ventilation scheme can be easily adapted. The results of its application to a urban tunnel show that the relative errors are 1.1~6.8% for the natural velocity, 1.3% for the traffic-induced velocity and 2.9% for the total air quantity. Simulated CO concentrations along the entire tunnel show about 13% of the relative error.

• Journal of the Korea Society for Simulation
• /
• v.27 no.2
• /
• pp.71-81
• /
• 2018

Forklifts in a shipyard lift and transport heavy objects. Tasks occur dynamically and the rate of the task occurrence changes over time. Especially, the rate of the task occurrence is high immediately after morning and afternoon business hours. The weight of objects varies according to task characteristic, and a forklift also has the workable or allowable weight limit. In this study, we propose an online forklift dispatching algorithm based on nearest-neighbor dispatching rule using minimal cost assignment approach in order to attain the efficient operations. The proposed algorithm considers various types of forklift and multiple jobs at the same time to determine the dispatch plan. We generate dummy forklifts and dummy tasks to handle unbalance in the numbers of forklifts and tasks by taking their capacity limits and weights. In addition, a method of systematic forklift selection is also devised considering the condition of the forklift. The performance indicator is the total travel distance and the average task waiting time. We validate our approach against the priority rule-based method of the previous study by discrete-event simulation.

• KIPS Transactions on Computer and Communication Systems
• /
• v.10 no.7
• /
• pp.205-214
• /
• 2021

For smart manufacturing, most semiconductor sites utilize automated material handling systems(AMHS). As one of the AMHSs, the OHT control system(OCS) manages overhead hoist transports(OHT) that move along rails installed on the ceiling. This paper proposes a real-time scheduling system to efficiently allocate and control the OHTs in semiconductor logistics processes. The proposed system, as an independent subsystem within the OCS, is interconnected with the main subsystem of the OCS, so that it can be easily modified without the effect of other systems. To develop the system, we first identify the functional requirements of the semiconductor logistics process and classify several types of control scenarios of the OHTs. Next, based on SEMI(Semiconductor Equipment and Materials International) standard, we design sequence diagrams and interface messages between the subsystems. The developed system is interoperated with the OCS main subsystem and the database in real time and performs two major roles: 1) OHT dispatching and 2) pathfinding. Six integrated tests were carried out to verify the functions of the developed system. The system was normally operated on six basic scenarios and two exception scenarios and we proved that it is suitable for the mission planning of the OHTs.

• The Journal of the Korea Contents Association
• /
• v.19 no.3
• /
• pp.520-529
• /
• 2019

This study is intended to provide basic data for health management of firefighters in the future by empirically looking into health hazard factors of firefighters in Busan City. It was revealed that firstly, the danger of harmful chemicals in a fire was perceived the most by firefighters, who extinguish a fire in person on the scene of a fire, and it was followed by the danger of falling while putting out a fire. This study is intended to provide basic data for health management of firefighters in the future by empirically looking into health hazard factors of firefighters in Busan City. It was revealed that firstly, the danger of harmful chemicals in a fire was perceived the most by firefighters, who extinguish a fire in person on the scene of a fire, and it was followed by the danger of falling while putting out a fire. Moreover, the danger of shift work was perceived the most by paramedics. This corresponds to the existing studies arguing that shift work is harmful to health. Next, the overload of patient transport was recognized as the second biggest hazard factor. This demonstrates they are worried about various second accidents that may happen due to a lot of patient transport works. In addition, the possibility of causing a traffic accident was perceived as a hazard factor too, since they must drive ambulance cars quickly to transport patients. Lastly, rescue workers regarded these hazard factors to be most dangerous. This is associated with their occupational characteristics, because rescue workers are the closest to diverse risks including a fire.

• Fire Science and Engineering
• /
• v.31 no.2
• /
• pp.119-126
• /
• 2017

This study examined the soundness, vibration, and size of ambulances currently used in Korea as well as the comfort and convenience of ambulancesin Korea. The target vehicles were measured and investigated using the currently used freight type, van type, and Benz ambulance. Currently, the ambulance standards in Korea have only formal production standards, and there is no regulation on safety for ambulances, space regulation for first aid, comfort, and convenience. Therefore, comparative experiments on the comfort and convenience were measured using noise and vibration measurement experiments, and research was conducted on the size and interior rearrangement of ambulances to investigate the areas that can improve the comfort and convenience. The noise measurementsshowed that the noise was large in the order of the van type, Benz type, and freight type. In the case of a speed of 40 km/h or more, the noise measurement result was 60 to 70 dB or more. In the case of vibration, the Benz type and van type ambulance were good, and the vibration of the freight type showed the worst result, highlighting the need for improvement. Lastly, it is not possible to increase the internal size of the structure of domestic ambulance. On the other hand, it is important that through ambulance relocation and the position of first aid personnel, it will be possible to use it more comfortably and conveniently.