• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.67-76
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• 2011

An exact curved path has to be fixed and velocity profile for travelling on the curved path is required by a moving stage. In this study, we decide the curved path on the basis of the information on three point locations. The path of the moving stage is traced by simulating the designed curve path and the velocity profile, and the results are compared with the given three points to determine how closely the moving stage follows the given path. Further, we propose a method to calibrate a curved path and velocity profile. The proposed moving paths were evaluated by performing experiments. Finally, the designed curved path and the actual path were compared.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.189-189
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• 2004

본 논문은 CNC 밀링머신을 이용한 절삭가공 등 2축시스템의 위치제어 시스템을 대상으로 한다. 기존의 제어방식은 크게 독립축제어와 상호결합제어로 분류할 수 있다. 독립축제어는 두 축의 통합된 운동을 각각의 독립된 축에 대한 추적제어를 수행하여 원하는 공구경로의 위치 정밀성을 향상시키고자 하는 것이고, 상호결합제어는 지령경로에 대한 추적성능보다는 현재의 윤곽오차를 감소시키는 방향으로 제어입력을 인가하여 가공윤곽의 오차를 감소시키는데 주목적이 있다. 또한 최근의 작업공정의 고속화 경향은 윤곽오차를 감소시키면서도 추적성능이 우수한 제어방식을 요구하고 있다.(중략)

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.452-453
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• 2008

전 차륜 조향 굴절차량의 자동안내제어를 위한 기준경로와의 편차 되먹임 방식은 곡선경로에서 발생하는 정상상태 오차를 줄이기 어렵다. 본 논문은 이 차량의 자동안내제어의 성능향상을 위한 전향보상기 설계에 대해 기술한다.

• Transactions of Materials Processing
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• v.7 no.5
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• pp.489-495
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• 1998

Spinning is a chipless forming method for producing axially symmetric parts by using axial-radial motions of a spinning roller. This process has still some advantages in such a view point that a variety of complex shapes which can not be formed in a press can be easily spun at a low cost although it is one of the oldest forming methods for spinning mainly cookware parts for a long time. This study is to investigate the optimum roller path in order to obtain the maximum spinnability in producing cylindrical cups of Aluminum(A1050-H16) sheet metal. Working conditions applicable to any size of blank were predetermined through preliminary spinning tests. 9 types of roller path were proposed and experiments were carried out. The modified involute curve was shown to give the maximum drawing ration and more uniform quality of spun cups as compared with other results of this study. in addition thickness distribution and dimensional accuracy of spun cups were examined and discussed.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.551-557
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• 2004

미래의 텔레매틱스(telematics)환경에서 차량항법과 관련된 주요 핵심 기술은 동적 경로 안내 이외에 차량 자체의 지능화를 통해 운전자에게 주행 중인 도로에서 급경사, 급커브 구간에 대한 정보를 사전에 경고함으로써 사고를 방지하는 운전자 보조 및 경고 시스템(driver assistance and warning system) 구현으로 전망되고 있다. 이와 같은 기술이 구현되기 위해서는 현재 차량항법용 수치도로지도에서 도로의 단순 위치정보만으로는 불가능하며 도로의 곡선구간에서 평면 곡선반경과 같은 도로의 선형설계요소에 대한 정보가 필수적이다. 따라서 본 연구에서는 현재 전국적으로 구축되어있는 1/1000 수치지도의 도로중심선을 이용하여 실제 도로의 평면 선형설계요소를 자동으로 추출하기 위한 알고리즘을 개발하였고 이를 GUI 환경의 프로그램으로 구현함으로써 기존 도로의 정확한 평면 선형정보를 경제적이면서 효율적으로 획득할 수 있게 되었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.162-168
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• 2006

Understanding of propagation characteristics is very important for the wireless communication system design and wireless communication service construction. In this paper, propagation characteristics is measured and analyzed at 2.45Ghz frequency band under curved subway tunnel environment. We constituted channel measurement system with sliding correlation and five different kind of antennas. The purpose of five different type of antennas is to compare propagation characteristics according to beam shape of antennas. The path loss under tunnel environment is average $4.38^{\sim}14.41dB$ lower than free space and circular polarization antenna marked smallest path loss. Also, path loss is smallest when the receiver antenna located outside of tunnel in th curved section. 90% of delay components of all antennas measured within 20ns and directional antenna has more wide coherence bandwidth than omni-directional antenna. According to measured result, when we consider path loss and delay characteristics, circular polarization antenna is most suitable under tunnel environment.

• Korean Journal of Child Studies
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• v.30 no.4
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• pp.69-85
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• 2009

The purpose of this study was to identify developmental trajectories of externalizing problems in preschoolers and to investigate dimensions of temperament and parental behaviors associated with trajectory groups. Subjects were 180 3- to 5-year-old preschoolers (96 males, 84 females) in the metropolitan area of Seoul. They were assessed three times at 5 month intervals over a one year period. Teachers reported on children's behavior problems, and parents reported on children's temperaments. Latent Growth Curve Modeling Analysis with cohort sequential design revealed externalizing behaviors gradually decreased between 3 and 6. At the 6-year-old level externalizing behaviors were associated with high novelty seeking temperament. The results were discussed in terms of the importance of longitudinal research in developmental psychopathology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.265-276
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• 2017

In this paper, a robust and more accurate trajectory tracking control method for a mobile robot is proposed using WIPDC(Weighted Integral Parallel Distributed Compensation) and T-S Fuzzy disturbance observer. WIPDC reduces the steady state error by adding weighted integral term to PDC. And, T-S Fuzzy disturbance observer makes it possible to estimate and cancel disturbances for a T-S fuzzy model system. As a result, the trajectory tracking controller based on T-S Fuzzy disturbance observer shows robust tracking performance. When the initial postures of a mobile robot and the reference trajectory are different, the initial control inputs to the mobile robot become too large to apply them practically. In this study, also, the problem is solved by designing an initial approach path using a path planning method which employs $B\acute{e}zier$ curve with acceleration limits. Performances of the proposed method are proved from the simulation results.

• Journal of the Korean Society for Railway
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• v.15 no.4
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• pp.364-369
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• 2012

This paper presents an experimental study on the radio propagation characteristics in subway tunnel at 18GHz frequency band which has been assigned to video transmission between train and wayside. The radio propagation tests are carried out in the subway tunnel of Seoul Metro using the antenna and communication devices of the prototype video transmission system. The measurement results show that 18GHz radio propagation in subway tunnel has smaller path loss than that of general outdoor radio environment. It is also cleared that the arch-type tunnels have smaller radio propagation losses than rectangular tunnels, and single track tunnels have smaller pass loss than double track tunnels. From the measurements, the radio propagation coverage is worked out as 520 meters. The curved tunnels which cannot have LOS communication between transmitter and receiver have large pass losses and fluctuation profile along distance. The radio propagation coverage along curved tunnels is worked out as 300 meters. These investigation results can be used to design the 18GHz radio transmission system for subway tunnel by providing the optimized wayside transmitter locations and handover algorithm customized to the radio propagation characteristics in subway tunnels.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.4
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• pp.304-310
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• 2017

In this paper, we propose the architecture of an IPM based lane detector for autonomous vehicles to detect and control the driving route along the curved lane. In the IPM image, we divide the area into two fields, Far/Near Field, and the lane candidate region is detected using the Hough transform to perform the matching for the curved lane. In autonomous vehicles, various algorithms must be embedded in the system. To reduce the system resources, we proposed a method to minimize the number of memory accesses to the image and various parameters on the external memory. The proposed circuit has 96% lane recognition rate and occupies 16% LUT, 5.9% FF and 29% BRAM in Xilinx XC7Z020. It processes Full-HD image at a rate of 42 fps at a 100 MHz operating clock.