• The KIPS Transactions:PartB
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• v.14B no.3 s.113
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• pp.163-170
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• 2007

In autonomous navigation of a mobile vehicle or a mobile robot, localization calculated from recognizing its environment is most important factor. Generally, we can determine position and pose of a camera equipped mobile vehicle or mobile robot using INS and GPS but, in this case, we must use enough known ground landmark for accurate localization. hi contrast with homography method to calculate position and pose of a camera by only using the relation of two dimensional feature point between two frames, in this paper, we propose a method to calculate the position and the pose of a camera using relation between the location to predict through perspective transform of 3D feature points obtained by overlaying 3D model with previous frame using GPS and INS input and the location of corresponding feature point calculated using KLT tracking method in current frame. For the purpose of the performance evaluation, we use wireless-controlled vehicle mounted CCD camera, GPS and INS, and performed the test to calculate the location and the rotation angle of the camera with the video sequence stream obtained at 15Hz frame rate.

• Journal of KIISE
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• v.43 no.1
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• pp.40-46
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• 2016

Digital road map generation is primarily based on artificial satellite photographing or in-site manual survey work. Therefore, these map generation procedures require a lot of time and a large budget to create and update road maps. Consequently, people have tried to develop automated map generation systems using GPS trajectory data sets obtained by public vehicles. A fundamental problem in this road generation procedure involves the extraction of representative trajectory such as main roads. Extracting a representative trajectory requires the base data set of piecewise line segments(GPS-trajectories), which have close starting and ending points. So, geometrically similar trajectories are selected for clustering before extracting one representative trajectory from among them. This paper proposes a new divide- and-conquer approach by partitioning the whole map region into regular grid sub-spaces. We then try to find similar trajectories by sweeping. Also, we applied the $Fr{\acute{e}}chet$ distance measure to compute the similarity between a pair of trajectories. We conducted experiments using a set of real GPS data with more than 500 vehicle trajectories obtained from Gangnam-gu, Seoul. The experiment shows that our grid partitioning approach is fast and stable and can be used in real applications for vehicle trajectory clustering.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.4
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• pp.555-562
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• 2023

The Railway Safety Act of 2014 strengthened the 'Railway Safety Management System' to establish autonomous safety management for railway operators and railway facility managers. Accordingly, it is required to establish and implement risk assessment and safety measures for risk management. However, the current risk assessment system is carried out at the fragmented safety management level within individual fields, which has caused difficulties in establishing and implementing risk assessment and safety measures. In addition, the technical standards of the safety management system stipulate that risk assessment of railway operators is mandatory, so standardized standards for risk assessment of railway facilities and railway vehicle maintenance are needed. Therefore, in this paper, we first verified railway risks by analyzing railway accident data for the last 10 years, and proposed a standardized framework to effectively assess and manage risks through a case study of a condition-based smart maintenance system developed based on railway vehicle maintenance data.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.6_1
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• pp.483-491
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• 2013

By a development of car navigation systems and mobile or positioning technology, it increases interest in location based services, especially pedestrian navigation systems. Updating of digital maps is important because digital maps are mass data and required to short updating cycle. In this paper, we proposed change detection for different network data-sets based on areal feature matching. Prior to change detection, we defined type of updating between different network data-sets. Next, we transformed road lines into areal features(block) that are surrounded by them and calculated a shape similarity between blocks in different data-sets. Blocks that a shape similarity is more than 0.6 are selected candidate block pairs. Secondly, we detected changed-block pairs by bipartite graph clustering or properties of a concave polygon according to types of updating, and calculated Fr$\acute{e}$chet distance between segments within the block or forming it. At this time, road segments of KAIS map that Fr$\acute{e}$chet distance is more than 50 are extracted as updating road features. As a result of accuracy evaluation, a value of detection rate appears high at 0.965. We could thus identify that a proposed method is able to apply to change detection between different network data-sets.

• 월간낙농육우
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• v.34 no.8
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• pp.162-165
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• 2014

국내 낙농경영이 복합경영에서 규모화된 전업농 또는 기업농 형태의 단일경영으로 빠르게 변하고 있다는 것은 모두가 알고 있는 사실이다. 이에 따라 착유시설 또한 많은 변화가 있었으며, 사육규모 및 두당 유생산랑과 정(正)의 상관관계를 갖고 있다. 국내 낙농산업의 초창기 또는 본격적인 도입기였던 1970년대와 1980년대 초반은 가구당 착유우 두수가 10두 미만이었으며 주로 손으로 착유를 하였다. 1980년대 중반 이후, 콤프레셔와 버킷설비가 목장에 도입되었으며, 냉각기 보조금 지급 및 보냉 집유차량이 목장별로 운행하기 시작하였다. 1990년대에는 버킷식 착유기가 파이프라인식 착유기로 전환되면서 착유시스템이 일부 자동화됨에 따라 노동력을 낮추고 원유의 위생안전성을 향상시킬 수 있었다. 2000년대에는 많은 목장에서 탠덤 또는 헤링본식 착유시스템을 도입하였으며, 이후 일부 착유두수가 60두 이상인 대규모 농가에서는 자동착유시스템을 도입하여 현재에 이르고 있다. 사실 전업농, 기업농으로 전환된 단일경영에서 지동착유시스템의 도입에 많은 관심을 보이고 있으나, 고가의 자동칙유시스템에 대한 한정된 정보에서 기인하는 리스크(위험요소) 등으로 인하여 섣불리 결정을 내리지 못하고 있는 실정이다. 이에 자동착유시스템의 구성 국내 외 도입 현황 및 장 단점 사례조사 결과와 함께 현재 농가의 자동착유시스템 도입 결정에 도움을 주기 위해 진행하고 있는 연구 과제를 소개하고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.374-377
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• 2005

Automobile is in charge of most transportation system in modern urban city. However, in fact, cause of problem of road state, environment, and the other reasons, urban transit system is using as Mass Transit nowadays. Nevertheless Urban transit system is considering many kind of safety fact of that system which is increasing continuously nowadays, it occurs various train accident. This paper describes 3D Dimensional Measurement(EDM testing) and tensile testing results of carbody structure for crashed EMU(Electric Multiple Units). Tensile tests were performed on two different types of specimens in order to evaluate the strength changes before and after damages, obtained from plastic deformed area and nondeformed region of the crashed EMU. And Structural analysis of EMU was performed for the criteria of safety assessment. Structural analysis using commercial I-DEAS software provided important information on the stress distribution and load transfer mechanisms as well as the amount of damages during rolling stock crash. The testing results have been used to provide the critical information for the criteria of safety diagnosis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3882-3888
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• 2012

In order to operate trains both mainline railroad platform and metropolitan subway line platform, it is necessary to develop the doorstep equipment of the rolling stock regardless of low(500mm, mainline) and high level platforms(1,135mm, metropolitan subway line) because of the requisite door safety system. In this study, two different types of platforms were examined. On closer examination, it seems that the conceptual design is suitable for telescopic sliding type doorstep equipment to minimize damage to the carbody underframe of railway vehicles and can also minimize the variation of the distance between the railway platform. Furthermore, the operation process and control flowchart of doorstep equipments by stages are proposed by various performance requirements.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.6
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• pp.114-121
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• 2010

This paper presents a design process of light-weighted fuel cell vehicle (FCV) frame to meet design target of natural frequency in early design stage. At first, using validated FE model for the current design, thickness optimization was carried out. Next. optimization process, comprised of beam model size optimization, shell model design and shell model thickness optimization, was investigated for two frame types. In addition, in order to ensure hydrogen tanks safety against rear impact load, structural collapse characteristics was estimated for the rear frame model finally produced from the previous optimization process and, with the target of equal collapse characteristics to the current design model, structural modification with small weight increase was studied through static structural collapse analyses. The same attempt was applied to the front side frame. The results explain that the proposed process enables to design light-weighted frames with high structural performance in early stage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1103-1114
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• 2000

Recent attempt to enhance the safety against collision reshaped the simple shell structures into the integrated complex shell structures. Moreover, due to various regulations continuously tightened for environment protection, weight reduction of automobiles becomes an increasingly important issue. Auto parts lightening is mainly accomplished by more reasonable design, adoption of lighter materials and miniaturization of the auto bodies. Focusing on the locally enhanced design approach among the above three ways, we here attempt to develop a patching optimization method, and also to determine the thicknesses of an integrated shell structure, both bringing a specified amount of stress relaxation. We first select a cross member as a patching optimization model. Based on the finite element stress calculations, we relieve the stress of cross member by patching in two ways-nonuniform thickness patching and optimized uniform thickness patching, the latter of which is more effective in a practical point of view for the preset amount of stress relaxation. Selecting a box type subframe as another finite element analysis model, we then determine the thickness of each part by axiomatic design approach for a preset amount of stress relaxation. The patching methodology and the axiomatic approach adopted in this work can be applied to the other complex shell structures such as center member and lower control arm.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1243-1248
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• 2010

Fatigue design and evaluation of welded joints are typically carried out by weld classification approach in which a family (theoretically infinite) of parallel nominal stress based S-N curves are used according to joint types and loading modes as well as extrapolation-based hot spot stress. Traditional finite element methods are not capable of consistently capturing the stress concentration effects on fatigue behavior due to their mesh-sensitivity in stress determination at welds resulted from notch stress singularity. The extrapolated hot spot stresses tend vary, depending on the element sizes, types, joint types, and loading mode. however, the equilibrium-equivalent structural stress method(E2S2) has been recently developed through several joint industry projects as a robust method to analyze welded components using finite element analysis. This method has been proven effective in correlating a large amount of published fatigue test results in the literature such as master S-N curve and has used for evaluating the fatigue life of welding components. In this study, fatigue analysis of the welding bogie frame is examined using E2S2 method with master S-N curve.