• 한국항해항만학회지
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• 제44권6호
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• pp.447-452
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• 2020

겨울철 온대저기압은 세력이 강하여 해양사고의 주요 원인이 되는 등 선박의 안전 운항에 있어서 매우 중요하다. 이 연구에서는 겨울철(2019년 12월~2020년 2월)의 기상 데이터를 이용하여 제1태평양한대전선대 부근의 온대저기압에 대하여 분석하였다. 분석 결과는 다음과 같다. 3개월 동안에 제1태평양한대전선대 부근에서 발생한 온대저기압은 총 41개이고, 그 중 8개가 현저히 발달하였다. 가장 강력한 온대저기압의 중심기압은 947hPa이다. 발생 위치 별 온대저기압은 일본 동쪽 태평양이 가장 많았고(16개), 그 다음은 우리나라 주변, 동중국해, 일본 남쪽 해상 순이었다. 주요 이동 경로는 크게 5가지로 구분할 수 있는데, 공통적으로 북동진하는 패턴을 보였다. 겨울철에 북태평양을 항해하는 선박이 온대저기압을 조우할 경우 선박의 최적항로는 동항 시에는 온대저기압 중심의 남측을, 서항 시에는 온대저기압 중심의 북측을 항해하는 것이다.

• 한국항만학회지
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• 제9권1호
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• pp.45-56
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• 1995

Investigation of the physical behavior of dredged material disposal in coastal water includes estimations of water column concentration in the receiving water, exposure time, the initial deposition pattern as well as thickness of material at the dumping fields near the estuary area. Calculation based on vertical setting and horizontal advection of single particles ignore the effects of bulk properties of the disposed material, vertical and horizontal diffusion, and material dilution due to the entrainment of ambient water during descent. This paper focuses on the spatial and temporal changes in the dumping fields for the water column and bottom at a hypothetically confined coastal water, where the ambient time-invariant velocity and density profiles are applied, within the initial time period following the instantaneous release of the dredged material. This model accounts the behavior of material after release divided into three phases: convective descent, dynamic collapse and long-term passive dispersion

• 한국항만학회지
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• 제14권1호
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• pp.87-95
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• 2000

This stability of a plate structure is very crucial problem which results in wrinkle and buckling. In this study, the effect of the pattern of spot-welding points of the two rectangular plates on the compressive and shear buckling load is studied with respect to the thickness, aspect ratio of plates and number of welding spots. Buckling coefficient of the plate not welded was compared with that of two plates with various thickness to extract the effect of thickness. The effect of number of welding spots are studied in two directions, longitudinal and transverse directions. The conclusions obtained were that the reinforcement effect was maximized when the aspect ratio was close to 1.75 at compressive load condition and that the effect of number of welding spots in transverse direction was larger than that in longitudinal direction at shearing load condition.

• Journal of information and communication convergence engineering
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• 제15권3호
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• pp.182-186
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• 2017

Maintaining a proper lookout activity routine is integral to preventing ship collision accidents caused by human errors. Various subjective measures such as interviewing, self-report diaries, and questionnaires have been widely used to monitor the lookout activity patterns of navigators. An objective measurement of a lookout activity pattern classification system is required to improve lookout performance evaluation in a real navigation setting. The purpose of this study was to develop an objective navigator lookout activity classification system using wearable accelerometers. In the training session, 90.4% accuracy was achieved in classifying five fundamental lookout activities. The developed model was then applied to predict real-lookout activity in the second session during an actual ship voyage. 86.9% agreement was attained between the directly observed activity and predicted activity. Based on these promising results, the proposed unobstructed wearable system is expected to objectively evaluate navigator lookout patterns to provide a better understanding of lookout performance.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.573-581
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• 2004

A self-contained wall climbing robot, called MRWALLSPECT (Multi-functional Robot for WALL inSPECTion) II, is developed. It is designed for scanning external surfaces of gas or oil tanks with small curvature in order to find defects. The robot contains all the components for navigation in itself without any external tether cable. Although it takes the basic structure of the sliding body mechanism, the robot has its original characteristic features in the kinematic design with closed link mechanism, which is enabled by adopting a simple and robust gait pattern mimicking a biological system. By employing the proposed link mechanism, the number of actuators is reduced and high force-to-weight ratio is achieved. This paper describes its mechanism design and the overall features including hardware and software components. Also, the preliminary results of experiments are given for evaluating its performances.

• 한국정보처리학회논문지
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• 제4권12호
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• pp.3023-3032
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• 1997

본 논문에서는 최소한의 구조성을 갖는 하이퍼스페이스 학습 환경에서의 수업 진행에 있어서 두가지 개별적 인 차이에 관하여 연구하였다. “펄 하버”라는 하이퍼 스택의 사용에 있어서 GEFT(Group Embeded Figure Test)를 통해 보면, 장 종속적인(Fleld Dependsnt) 사용자는 장 독립적인(Field Independent) 사용자보다 더욱 자주 지침서를 사용하였으며, 연구후 FI 사용자가 궁극적으로는 더욱 높은 시험 결과를 보여 주었다. 또한, FD 사용자가 일정한 형식의 진행 과정을 보여 주지 않은 데 반해, FI 사용자는 일정한 형태의 학습 진행 과정을 나타내었으며, 영상 사고가 높은 학습자가 하이퍼스페이스 학습환경에서 더욱 큰 교육 효과를 얻게되는 것으로 나타났다．

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.527-529
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• 2006

In this paper, we find a robot's path using a Virtual Reality Modeling Language and overlay vision. For correct robot's path we describe a method for localizing a mobile robot in its working environment using a vision system and VRML. The robt identifies landmarks in the environment, using image processing and neural network pattern matching techniques, and then its performs self-positioning with a vision system based on a well-known localization algorithm. After the self-positioning procedure, the 2-D scene of the vision is overlaid with the VRML scene. This paper describes how to realize the self-positioning, and shows the overlap between the 2-D and VRML scenes. The method successfully defines a robot's path.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.258-260
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• 2005

We describe a method for localizing a mobile robot in the working environment using a vision system and VRML. The robot identifies landmarks in the environment and carries out the self-positioning. The image-processing and neural network pattern matching technique are employed to recognize landmarks placed in a robot working environment. The robot self-positioning using vision system is based on the well-known localization algorithm. After self-positioning, 2D scene is overlaid with VRML scene. This paper describes how to realize the self-positioning and shows the result of overlaying between 2D scene and VRML scene. In addition we describe the advantage expected from overlapping both scenes.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2007년도 춘계학술발표대회
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• pp.1352-1355
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• 2007

수도권에서 가장 신뢰받고 많이 이용되어지는 대중교통 지하철이라는 대중교통 자원을 훨씬 더 효율적으로 이용할 수 있도록 광범위한 특정 사용자층을 대상으로 한다는 것에 연구의 큰 효율성과 차별성을 가지고 있다. 이미 이전에 관련기반에 대한 특허 있어서는 많은 부분 특허출원이 되고 연구되었지만 상업화에 대한 뚜렷한 성과가 없고, 기술적인 구현에 있어서도 좀 더 보강하여 상업화와 기술적인 구현에 대한 가이드라인을 제시하였다.

• 제어로봇시스템학회논문지
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• 제16권6호
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• pp.601-607
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• 2010

For commercial success of emerging service robots, the fault tolerant technology for system reliability and human safety is crucial. Traditionally fault tolerance methods have been implemented in application level. However, from our studies on the common design patterns in fault tolerance, we argue that a framework-based approach provides many benefits in providing reliability for system development. To demonstrate the benefits, we build a framework-based fault tolerant engine for OPRoS (Open Platform for Robotic Services) standards. The fault manager in framework provides a set of fault tolerant measures of detection, isolation, and recovery. The system integrators choose the appropriate fault handling tools by declaring XML configuration descriptors, considering the constraints of components and operating environment. By building a fault tolerant navigation application from the non-faulttolerant components, we demonstrate the usability and benefits of the proposed framework-based approach.