• 한국항해학회지
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• 제21권4호
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• pp.93-102
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• 1997

History will be defined as a science on human beings in both space and time(des hommes dans le temps et l'espace). Navigational History is a premise to compose Maritime History. Maritime History is a branch of General History which is classified on the basis of space and will be definded as a branch of history to examine 'inter-realtions between maritime affairs and inland affairs'. Then, what kind of 'go by sea'can be a subject of Navigational History ? A research-subject of Navigational History must be navigation rather than sail or voyage. Because while 'sail' means to 'passive and noncommercial sailing' and voyage means to journeyin a general sense that includes sail and navigation, navigation means to indicate ' to go from one place to another in a ship' adn 'to convoy goods by water'. Then, how can we define Navigation History? Navigational History in a narrow sense is to be a field of studying 'process of development of nautical science and seamanship on the side of History ofScience and Techique, whereas Navigational History in a broad sense is to be a field of analyzing 'effects of historical navigation upon history on the side of General History. On studying Navigational History in a narrow sense, there are signifiacances of disclosing what the development of nautical instruments and arts of navigation have played a role in history. Navigational History in a broad sense is a branch of General History to study effects of historical navigation upon history. In conclusion, the significance of studying Navigation History is to disclose process of developmentof arts of navigation, and on the basis of this study is to reveal how the human elements operate in historical navigation. In short, it should not cease to study Navigational History in a narrow sense, and should enlarge its perspective of research toward Navigational History in a broad sense.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.871-875
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• 2003

To detect and avoid obstacles is one of the important tasks of mobile navigation. In a real environment, when a mobile robot encounters dynamic obstacles, it is required to simultaneously detect and avoid obstacles for its body safely. In previous vision system, mobile robot has used it as either a passive sensor or an active sensor. This paper proposes a new obstacle detection algorithm that uses a stereo camera as both a passive sensor and an active sensor. Our system estimates the distances from obstacles by both passive-correspondence and active-correspondence using laser slit. The system operates in three steps. First, a far-off obstacle is detected by the disparity from stereo correspondence. Next, a close obstacle is acquired from laser slit beam projected in the same stereo image. Finally, we implement obstacle avoidance algorithm, adopting the modified Dynamic Window Approach (DWA), by using the acquired the obstacle's distance.

• 한국항행학회논문지
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• 제9권2호
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• pp.93-102
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• 2005

본 논문은 휴대인터넷시스템의 수동피코셀 제안과 엑세스포인트와 수동형 피코셀간의 ROF(Radio over Fiber)접속 구도에 대한 것이다. 휴대인터넷시스템(Wibro)은 시속 60km의 중속도의 이동 단말에 50Mbps의 IP 기반 데이터서비스를 제공하는 것이다. 따라서 서비스를 제공하기 위하여 초기에 셀의 구축비용을 최소화 하는 것이 요구된다. 본 논문은 이러한 요구사항을 만족하는 수동형 피코셀을 제안하고 이의 접속구도에 대하여 제안한 것이다. 기존의 FP(Fabry-Perot) 레이저를 채용하는 경우 ROF 링크의 비선형 특성을 측정하여 Wibro시스템에 접속 가능성을 검증하였다.

• 한국항행학회논문지
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• 제17권6호
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• pp.658-663
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• 2013

본 논문에서는 비아 트랜지션을 이용하여 마이크로스트립 선로를 구현하고 이것을 이용하여 다층 레이어를 사용하여 링 하이브리드 결합기를 설계하였다. 여기서 사용된 트랜지션은 서로 다른 레이어에 존재하는 마이크로스트립 선로를 연결하기 위해서 비아를 사용한 샌드위치 구조이다. 컴팩트한 RF/ 마이크로웨이브 소자를 설계하기 위해서 이러한 비아를 이용한 마이크로스트립 선로의 구현은 긴 전송선로를 짧게 구현할 수 있다. 이러한 트랜지션의 유용성을 보이기 위해서 중심 주파수 2 GHz에서 링 하이브리드 결합기를 구현하였다. 그 결과 특성은 시뮬레이션과 거의 동일함을 확인하였고, 크기는 기존 것과 비교하여 50% 줄일 수 있다.

• 한국항행학회논문지
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• 제27권4호
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• pp.469-472
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• 2023

If temperature management is required in factory or environmental monitoring, temperature can be measured by connecting various sensors wired or wirelessly. Surface acoustic wave sensors measure temperature using changes in acoustic waves on the sensor surface according to temperature, and are useful for wireless networks. In this paper, in order to build a wireless temperature measurement system in the 900 MHz frequency band, the temperature characteristics of the passive SAW sensor were measured, and the analysis and removal of multipath reflection wave effect inside the high temperature chamber were conducted. The resonant frequency of the SAW sensor was measured, and radio transmission/reception and multipath reflected wave removal techniques were proposed in the shielded chamber.

• 한국항해항만학회지
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• 제34권4호
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• pp.287-292
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• 2010

The purpose of this study was to create a cyber-training & education program in response to the needs of skippers and crews operating tug-barges within Korean coastal waters and the rapid changers in this industry. Skippers and crews are inclined to operate tug-barges on the basis of experience rather than information. It is not easy to provide useful information whenever they want or to drill them in safety management skills, because of their passive attitude toward education and the few opportunities that exist. In order to increase educational opportunities, efficiency and motivation, the authors have developed this program which consists of a 'tug bridge resource management module, risk perception training module, accident case module, operating module and navigation module', and are hoping that this program will enhance and strengthen all tug-barge operations. We are also putting all our energies into designing up to date animation programs and developing new scenarios concerning the method of evaluation and certification distribution.

• 한국정보통신학회논문지
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• 제5권6호
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• pp.1163-1168
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• 2001

거리 계측 시스템은 물체까지의 거리를 삼차원 좌표계에서 측정하는 장치이다. 군용 장비나 건설, 항해, 검사 조립, 로봇 비전 등에 널리 사용되는 무접촉식 원격 거리 계측(ranging) 시스템은 자동화 응용에 매우 중요하다. 계측 방식은 active와 passive방식으로 구분되는데, active방식은 laser나 microwave, 초음파 등의 time of flight를 이용하거나 레이저 조사(illumination)에 대한 카메라 영상을 해석하는 등의 다양한 방식이 있으나 장치가 복잡하며, passive 방식은 stereo camera의 양안영상을 이용하거나 focus특성을 이용하는 방식 등이 있으나 대부분 연산시간이 많이 요구된다. 본 연구에서는 수동식 스테레오 카메라에서 양안시차를 산출하여 triangulation으로 목표전의 거리를 측정하는 방식에서, 연산 시간이 많이 소요되는 과정을 고속으로 처리하는 새로운 방식을 제안하였다. 즉, 목표점에서의 양안 edge 영상을 구하고, 이 영상의 projection profile을 cross correlation하여, 시차를 고속으로 산출해 거리를 구하는 알고리즘을 제안하였으며, 이 방식의 효율성을 실험 결과를 통하여 보였다.

• Advances in robotics research
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• 제1권1호
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• pp.21-39
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• 2014

Due to the rapid progress in the field of robotics, it is a high time to concentrate on the development of a robot that can manoeuvre in all type of landscapes, ascend and descend stairs and sloping surfaces autonomously. This paper presents details of a prototype robot which can navigate in very rough terrain, ascend and descend staircase as well as sloping surface and cross ditches. The robot is made up of six differentially steered wheels and some passive mechanism, making it suitable to cross long ditches and landscape undulation. Static stability of the developed robot have been carried out analytically and navigation capability of the robot is observed through simulation in different environment, separately. Description of embedded system of the robot has also been presented and experimental validation has been made along with some details on obstacle avoidance. Finally the limitations of the robot have been explored with their possible reasons.

• 한국정밀공학회지
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• 제26권8호
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• pp.89-95
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• 2009

In this paper, a navigation algorithm is proposed using RFID tags in indoor environments. Firstly, a stochastic sensor model of RFID is derived and the design factors including the maximum identifiable distance, the identification direction and the read success rate are obtained through experiments. The obstacle avoidance algorithm is developed with consideration of those factors for a variety of RFID antenna configurations and different indoor environments. The algorithm is tested by computer simulations and implemented on a mobile robot.

• 한국항행학회논문지
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• 제15권5호
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• pp.857-864
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• 2011

오늘날의 교육은 강의를 통한 수동적 학습에서 벗어나 학습자 본인 스스로 자기 주도적 학습이 이루어 질 수 있도록 많은 노력을 기울이고 있다. 본 논문에서는 초등학생을 대상으로 하는 수학과목에 SCORM 기반의 수준별 오답분석시스템을 구현하였다. 학습자의 문제영역별, 문제능력별 취약점을 분석할 수 있고, 오답분석을 통한 개인의 수준에 맞는 보충학습으로 레벨이 낮은 그룹에 더 높은 학습 성취도 향상을 가져왔다.