• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.1996-2001
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• 2012

Visual inspection systems are widely proposed for the well formed surface materials like electronics parts. But the materials with ill reflection ability have many troubles when visual inspection system is introduced. We have developed a robust visual inspection system that can work well in spite of low reflection ratio and with much noise when truth model is not known in the mixed production line. A workpiece identification technique using k-means has been proposed to identify the type. Based on the identified type, a robust-to-noise segmentation method, called active contour, has been applied to segment the features from the image. Finally, Kalman filter has been applied to adapt the error variation. Experiment shows that performance is about to match the accuracy of manual measurement using projectors.

• Journal of Science Education
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• v.34 no.1
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• pp.175-184
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• 2010

We agree with Hanna and Jahnke's assertion on the use of arguments from physics in mathematical proofs and analyze their educational example of the use of arguments from physics in the proof of the center of gravity of a triangle. Moreover, we suggest practical models for the center of gravity of a triangle for the demonstration in a classroom. Comparing with the traditional mathematical arguments, the role of concepts and models from physics in arguments from physics will be clearly pointed out. Also, the necessity for arguments from physics in the classroom will be discussed in this paper.

• Journal of Korea Society of Industrial Information Systems
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• v.21 no.3
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• pp.21-28
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• 2016

Compressed sensing is a signal processing technique for efficiently acquiring and reconstructing in an under-sampled (i.e., under Nyquist rate) representation. Specially, a block compressed sensing with Smoothed Projected Landweber (BCS-SPL) framework is one of the most widely used schemes. Currently, a variety of BCS-SPL schemes have been actively studied. However, when restoring, block sizes have effects on the reconstructed visual qualities, and in this paper, both a basic scheme of BCS-SPL and several modified schemes of BCS-SPL with structured measurement matrix are analyzed for the effects of the block sizes on the performances of reconstructed image qualities. Through several experiments, it is shown that a basic scheme of BCS-SPL provides superior performance in block size 4.

• The Journal of Korean Physical Therapy
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• v.8 no.1
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• pp.1-14
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• 1996

The present case study has a object to investigate the changes in locomotion patterns of infant with athetoid cerebral palsy would be occured by the program when it is applied with upper extremity weight bearing. The subject has been limited to one infant over one year of age, selected from the patients in the physical therapy clinic, Rehabilitation Center, Taegu University. Subject is normal in the visual and auditory sense, but he is unable to walk on his own Subject weighted 2.9kg at birth and underwent severe postnatal kernicterus, always on the baby-walker at homo. He disliked supine position characteristic in moving in athetoid type before he was under the program. The program was applied 7 months. Each session of the program is composed of 7 stages : (1) prebriefing between the therapist and the parents (2) pretherapy amusement time of the infant (3) warming-up (4) upper extremity weight bearing (5) cooling-down (6) post-therapy amusement time (7) postbriefing. The locomotion of the subject is proved to be influenced by the program. He showed a leftward circular movement as a result of the exercise, reducing the involuntary movement of his head when he was positioned for crawling. Later he proceeded to develop into creeping, crawling, kneeling and finally cruising. In conclusion, it appeared evident that the locomotive abilities of the subject is improved by the program explored in this study. The higher locomotive patterns could be achieved such as crawling, sitting, kneeling and cruising wich enable the upper extremities weight bearing.

• The Journal of Korean Physical Therapy
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• v.17 no.3
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• pp.351-367
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• 2005

The purpose of this study was to identity effects of virtual reality(VR) program related to standing postural control on balance, gait and brain activation patterns in chronic hemiplegic stroke patients. Subjects were assigned randomly to either VR group (n=12) or the control group (n=12) when the study began. Both groups received conventional physical therapy for 2 to 3 times per week. In addition to conventional physical therapies, VR group trained 3 types of virtual reality programs using IREX for standing postural control during 4 weeks (4 times/week, 30 minutes/time). Subjects were assessed for static and dynamic balance parameters using BPM, functional balance using Berg Balance Scale related to movement of paretic lower limb before and after 4 weeks of virtual reality training. The results of this study were as follows. 1. Following VR training, VR group demonstrated the marked improvement on dynamic mean balance, anteroposterior limits of stability (AP angle) and mediolateral limits of stability (ML angle). 2. Following VR training, both groups scored higher on Berg Balance Scale. However, a comparison of mean change revealed differences between groups. In conclusion, these data suggest that the postural control training using VR programs improve dynamic and functional balance performance in chronic hemiplegic stroke patients.

• Journal of Welding and Joining
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• v.24 no.1
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• pp.43-49
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• 2006

This paper describes the friction surface modification which has been successfully developed with the friction stir welding recently There are several problems including just position control and backlash in conventional friction surface modification system. Therefore it has been developed the friction surface modification system which has been controlled precisely both position and force by driving hydraulic cylinder in this paper. The mechtrode rotation speed(N) and feeding speed(Vz), travel speed(Vx,y) are of critical importance for the width and thickness of the coating in friction surfacing process. But there is no theoretical method of determining interrelations between process parameters affect the coating width and thickness. As a result of DOE(design of experiment) with developed system, the coating thickness and width seemed to decrease according to increase the mechtrode rotation speed(N) and traveling speed(Vx,y), to decrease feeding speed(Vz) apparently. However as the result of regression analysis the main effect was only the mechtrode rotation speed in the coating thickness.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.4
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• pp.498-504
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• 2005

A fuzzy logic for collision avoidance of underwater robots is proposed in this paper. The VFF(Virtual Force Field) method, which is widely used in the field of mobile robots, is modified for application to the autonomous navigation of underwater robots. This Modified Virtual Force Field(MVFF) method using the fuzzy logic can be used in either track keeping or obstacle avoidance. Fuzzy logics are devised to handle various situations which can be faced during autonomous navigation of underwater robots. The obstacle avoidance algorithm has the ability to handle multiple static obstacles. Results of simulation show that the proposed method can be efficiently applied to obstacle avoidance of the underwater robots.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.487-492
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• 2004

본 연구에서는 인공신경망 기법을 이용하여 산사태 발생원인에 대한 가중치를 구하였다. 여름철 집중호우시 산사태가 많이 발생하는 강원도 강릉시 사천면 사기막리 와 주문진읍 삼교리에 해당한다. 산사태가 발생할 수 있는 요인으로 지형도로부터 경사, 경사방향, 곡률, 수계추출을, 정밀토양도로부터 토질, 모재, 배수, 유효토심, 지형을, 임상도로부터 임상, 경급, 영급, 밀도를, 지질도로부터 암상을, Landsat TM 영상으로부터 토지이용도와 추출하여 격자화 하였으며, 아리랑1호 영상으로부터 선구조를 추출하여 l00m 간격으로 버퍼링 한 후 격자화 하였다. 이렇게 구축된 산사태 발생 위치 및 발생요인 데이터 베이스를 이용하여 인공신경망 기법을 적용하여 산사태 발생 원인에 대한 상대적인 가중치를 구하였다. 인공신경망의 역전파 알고리즘을 이용한 사기막리 지역과 삼교리 지역의 산사태 가중치를 보면 GPS를 이용한 현장조사와 위성영상을 이용한 변화탐지 기법모두의 경우모두와 훈련지역을 실제 산사태 발생 지역과 경사도가 0°인 지역, 실제 산사태 발생 지역과 Frequence ratio를 이용하여 작성한 취약성도에서 산사태 발생이 낮을 것으로 예상되는 지역, Frequence ratio를 이용한 취약성도에서 산사태 발생이 높을 것으로 예상되는 지역 과 낮을 것으로 예상되는 지역의 경우에서도 경사도는 1.5～2.5배정도 높은 상대적 가중치를 나타냈다. 이러한 가중치는 산사태 취약성도를 작성하는데 활용될 수 있다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.229-233
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• 2004

원격탐사 자료를 이용하여 조간대 표층퇴적상의 분류가 가능하다면 현장조사와 상호 보완적으로 사용될 수 있다. 공간해상도 30 m 급의 Landsat 위성 자료를 이용하여 0.0625 mm 입자 기준에 의한 조간대의 표층 퇴적상 분류를 한 연구가 몇 차례보고 된 바 있지만, 스펙트럴 값만으로 퇴적상을 분류하기 위해서는 몇 가지 문제점이 따른다. 첫째는 점이적으로 변하는 조간대에서 입도와 위성자료 공간해상도와의 스케일 차이로 인한 mixed pixel(mixel)을 어떻게 분류할 것인가 이고 두 번째는 입도 요인 이외의 조간대 환경요인을 어떻게 고려해야 되느냐 하는 것이다. mixel에 대한 대안으로 4 m 공간해상도의 IKONOS 영상을 이용하였으며, 입도 이외의 다른 환경 요인은 조간대 지형과 조류로 (tidal channel)를 파악하여 퇴적상의 특성과 비교하였다. IKONOS를 이용한 조간대 퇴적상 분류 결과는 현장 조사 자료와 잘 일치하였으며 지형적으로 높고 조류로가 발달한 부분에 이질 퇴적상이 위치하는 것을 알 수 있었다. 이 연구는 IKONOS와 같은 공간해상도를 갖는 KOMPSAT II 위성이 2004년 진수되어 서해조간대 지역에 대해 다시기의 많은 영상을 확보할 수 있다면 조간대의 지형변화와 생태계 변화 등의 조간대 모니터링 연구에 활용되어 연안의 종합적이고 효율적인 관리에 활용될 수 있을 것으로 생각된다.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.10
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• pp.1008-1013
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• 2014

This paper introduces an adaptive anti-sway tracking control algorithm for container cranes with unknown payloads and friction between the trolley and the rail. If the friction effects in the system can be modeled, there is an improved potential to design controllers that can cancel these effects. The proposed control improves the sway suppressing and the positioning capabilities of the trolley and hoisting against uncertain payload and friction. The variable structure controls are first designed based on a class of feedback linearization methods for the stabilization of the under-actuated sway dynamics. The adaptation mechanism are then designed with parameter estimation of unknown payload and friction compensation for the trolley and hoisting, based on Lyapunov stability methods for the accurate positioning and fast attenuation of trolley oscillation due to frictions in the vicinity of the target position. The asymptotic stability of the overall closed-loop system is assured irrespective of variations of rope length. Simulations are shown under various frictions and external winds in the case of no priori information of payload mass.