• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1054-1059
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• 2005

The artificial potential method uses a potential field to guide a robot from a start to a goal configuration respectively. The potential field consists of attractive potential used to pull a robot toward a goal and repulsive potential to keep it away from obstacles. However, there are two problems concerning local minimum and computational cost to be resolved in conventional artificial potential methods. This study proposes a method utilizing a spline surface that interpolates arbitrary boundaries and a domain reduction method that reduces the unnecessary area. The proposed spline surface interpolates arbitrary shaped boundaries and is used as an artificial potential to guide a robot for global motion planning of a mobile robot. A reduced domain process reduces the unnecessary domain. We apply a distance-weighted function as such a function, which blends distances from each boundary with a reduction in computational time compared with other analytical methods. As a result, this paper shows that an arbitrary boundary spline surface provides global planning and a domain reduction method reduces local minimum with quick operation.

• 한국지능시스템학회논문지
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• 제22권1호
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• pp.1-6
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• 2012

이동로봇에 관한 연구가 널리 진행되고 있다. 본 논문에서는 미지의 공간에서 효과적으로 장애물을 회피할 수 있는 SFLC(single-input fuzzy logic controller) 기반의 이동로봇의 주행 제어기 설계와 구현을 제안한다. 장애물의 위치와 거리 인식을 위해 초음파센서를 사용하였으며, 좌, 우측 바퀴의 각속도 출력 제어를 위하여 퍼지논리시스템 기반의 제어기를 설계하였다. 퍼지제어기의 퍼지화 방법은 싱글톤 방법, 추론법은 간략화된 Mamdani의 추론법, 비퍼지화 방법은 간략화된 무게중심법을 사용하였다. 제안한 퍼지제어기의 성능 및 실제 적용 가능성의 평가를 위해 이동로봇의 모델링에 근거한 컴퓨터 시뮬레이션을 수행하였다. 그 결과 이동로봇이 장애물을 피하면서 목표지점에 정확히 도착함을 확인하였다. 더욱이 기존의 2-입력 퍼지논리시스템 기반의 제어기로부터 단일 입력을 가지는 단순구조 퍼지논리제어기를 설계할 수 있음도 보였다.

• 의학교육논단
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• 제13권2호
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• pp.47-57
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• 2011

Purpose: This study was conducted to explore the current usage of high integration mannequin human patient simulators (hereafter HPS) in nursing education. Methods: Thirty-two faculty members in 11 nursing schools participated in this survey. the questionnaire consisted of some multiple-choice questions and open questions to collect data on the experience of faculty members with using HPS as well as quantitative information. Results: The faculty members who used HPS in their classes recognized the need to use simulation in nursing education. They identified the advantages of simulation education as promoting adaptation to the clinical environment(46.9%), promoting self-confidence(28.1%), promoting critical thinking(28.15), and making direct nursing skill practice available(28.1%). However, they considered the obstacles to the use of simulation in nursing education to be insufficient manpower(62.5%), insufficient time(40.6%), and difficulty in preparing a teaching strategy(34.4%). Conclusion: HPS is useful in nursing education, but systematic plans and policies regarding on its operation are needed to confirm its effectiveness. The results of this study generally provide a basic information for use of HPS in nursing education.

• 한국항행학회논문지
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• 제10권4호
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• pp.377-384
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• 2006

본 논문에서는 선박이나 항공기 조난에 대비하여 운용 중인 인공위성을 기반으로 하는 수색 및 구조 시스템의 조난신호 탐지시간에 관한 문제를 고려한다. 현재 운용 중인 LEOSAR 시스템은 저궤도 위성을 사용하며 시스템에 속한 위성의 수가 적고 커버리지는 지구전체가 아닌 국지이다. 따라서 조난자의 비컨 신호가 탐지되어 구조본부까지 전달되려면 장시간이 소요된다. 이와 대조적으로 새로 제안된 중궤도 항행위성시스템에 기반한 MEOSAR 시스템을 추가로 도입하는 경우를 가정하면 커버리지가 지구전역으로 확대되고 시스템의 안정도가 개선되어 조난신호 검출 또는 탐지시간이 크게 감소하므로 수색구조 효율이 크게 개선된 결과를 얻는다. 본 논문에서는 비컨에 대한 장애물의 영향을 고려했을 경우에 대하여 LEOSAR 및 MEOSAR 시스템에 대한 조난신호 탐지시간을 시뮬레이션을 통하여 계산하고 그 결과를 비교 해석한다.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.352-362
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• 2014

In this paper, a fuzzy logic controller is designed for a DC motor which can be used for navigation control of mobile robots. These mobile robots can be used for agricultural, defense and assorted social applications. The robots used in these fields can reduce manpower, save human life and can be operated using remote control from a distant place. The developed fuzzy logic controller is used to control navigation speed and steering angle according to the desired reference position. Differential drive is used to control the steering angle and the speed of the robot. Two DC motors are connected with the rear wheels of the robot. They are controlled by a fuzzy logic controller to offer accurate steering angle and the driving speed of the robot. Its location is monitored using GPS (Global Positioning System) on a real time basis. IR sensors in the robot detect obstacles around the robot. The designed fuzzy logic controller has been implemented in a robot, which depicts that the robot could avoid obstacle as well as perform its operation efficiently with remote online control.

• 한국정보통신학회논문지
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• 제17권4호
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• pp.917-921
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• 2013

본 연구에서는 이중게이트 MOSFET의 전도중심에 따른 항복전압의 변화를 분석하였다. DGMOSFET에 대한 단채널효과 중 낮은 항복전압은 소자동작에 저해가 되고 있다. 항복전압분석을 위하여 포아송방정식의 분석학적 전위분포를 이용하였으며 이때 전하분포함수에 대하여 가우시안 함수를 사용함으로써 보다 실험값에 가깝게 해석하였다. 소자 파라미터인 채널길이, 채널두께, 게이트 산화막 두께 그리고 도핑농도 등에 대하여 전도중심의 변화에 대한 항복전압의 변화를 관찰하였다. 본 연구의 모델에 대한 타당성은 이미 기존에 발표된 논문에서 입증하였으며 본 연구에서는 이 모델을 이용하여 항복전압특성을 분석하였다. 분석결과 항복전압은 소자파라미터에 에 대한 전도중심의 변화에 크게 영향을 받는 것을 관찰할 수 있었다.

• Journal of Biosystems Engineering
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• 제25권2호
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• pp.131-140
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• 2000

Spraying operation is one of the most essential in an orchard management and it is also hazardous to human body. for automatic and unmanned spraying , an autonomous travelling vehicle is demanded. In this study, a telemeter was developed using infrared beam which could detect trunks and obstacles measure distance and direction from the vehicle travelling in the orchard. The telemeter system was composed of two infrared LED transmitters and receivers, a beam scanning device for continuous object detection , two rotary encoders for angle detector, and a beam level controller for uneven soil surface. The detected distance and direction signal s were sent to personal computer which made for the system display the angular and distance measurements through I/O board. According to a field test in an apple farm, the system detected up to 10m distance under 12 V of transmitted beam intensity, however, it was recommended that the proper beam transmit intensity be 7 v at the 10 m distance, because of the negative effect to human body at 12 V. The error rate of this system was 0.92 % when the actual distance was compared to measured one. The system was feasible at the small error rate. The developed telemeter system was an important part for autonomous travelling vehicle provided the real time object recognition . A direction control system could be constructed suing the system. It is expected that the system could greatly contribute to the development of autonomous farm vehicle.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.547-548
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• 2006

This study focuses on a determination of amount of Pt in the Pt/C for catalysts of polymer electrolyte membrane fuel cells (PEMFC). PEMFC offer low weight and high power density and being considered fur automotive and stationary power applications. The PEMFC behavior is quite complex is influenced by several factors, including catalysts and structure of electrode and membrane type. Catalyst of electrode is important factor for PEMFC. One of the obstacles preventing polymer electrolyte membrane fuel cells from commercialization is the high cost of noble metals to be used as catalyst, such as platinum. To effectively use these metals, they have to be will dispersed to small particles on conductive carbon supports. The optimal amount of Pt in Pt/C was investigated by using polarization curves in single cell with $H_2/O_2$ operation.

• 한국정밀공학회지
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• 제27권2호
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• pp.60-69
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• 2010

Lookup-Table (LUT) based fuzzy controller for obstacle avoidance enhances operations faster in multiple obstacles environment. An LUT based fuzzy controller with Positive/Negative (P/N) fuzzy rule base consisting of 18 rules was introduced in our paper$^1$ and this paper shows a 50-rule P/N fuzzy controller for enhancing performance in obstacle avoidance. As a rule, the more rules are necessary, the more buffers are required. This paper suggests LUT sharing method in order to reduce LUT buffer size without significant degradation of performance. The LUT sharing method makes buffer size independent of the whole fuzzy system's complexity. Simulation using MSRDS(MicroSoft Robotics Developer Studio) evaluates the proposed method, and in order to investigate its performance, experiments are carried out to Pioneer P3-DX in the LabVIEW environment. The simulation and experiments show little difference between the fully valued LUT-based method and the LUT sharing method in operation times. On the other hand, LUT sharing method reduced its buffer size by about 95% of full valued LUT-based design.

• 품질경영학회지
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• 제35권3호
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• pp.1-20
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• 2007

International standards are established by the agreement of many nations' delegates that represent the opinions from all stakeholders such as suppliers, manufacturers, customers, beneficial groups, and governments. The international standards provide all stakeholders with a scientific basis that determines regulations regarding quality, health, environment and other necessary issues. Among many international standards, the well known ISO 9000 quality management system(QMS) has been installed in about 877,770 organizations in 161 countries up until now. This ISO 9000 QMS specifies requirements for detailed contents from supply of resources to delivery to customers for registering QMS certificate. This paper considers business values of ISO 9000 QMS by reviewing literature. We summarize issues related to installment and operation : motives, advantages, disadvantages, problems, obstacles, and lessons. We also summarize the integrated management system(IMS) issues and compare ISO 9000 with Total Quality Management(TQM). We present a comprehensive figure and tables based on the category of the main results of literature.