• 자동차안전학회지
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• 제12권3호
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• pp.43-51
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• 2020

Currently, the second level of the six stages of self-driving technology, as defined by SAE, is commercialized, and the third level is preparing for commercialization. The purpose of ACC is to be evaluated as a system useful for preventing and preventing accidents by minimizing driver fatigue through longitudinal speed control and relative distance control of the vehicle. In this regard, for the study of safety assessment methods in the practical environment of ACC. Distance measurement method using monocular camera and data acquisition equipment such as DGPS are utilized. Based on the evaluation scenario considering the domestic road environment proposed by the preceding study, the relative distance obtained from equipment such as DPGS and the relative distance using a monocular camera in the actual test is verified by comparing and analyzing the safety assessment. The comparison by scenario results showed a minimum error rate of 3.83% in Scenario 1 and a maximum of 14.61% in Scenario 6. The cause of the maximum error is that the lane recognition is not accurate in the camera image and irregular operation conditions such as rushing in or exiting the surrounding area from the walkway. It is expected that safety evaluation using a monocular camera will be possible for other ADAS systems in the future.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권4호
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• pp.223-232
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• 2003

This paper presents a new method driving multiple robots to their goal position without collision. Each robot adjusts its motion based on the information on the goal location, velocity, and position of the robot and the velocity and position of the .other robots. To consider the movement of the robots in a work area, we adopt the concept of avoidability measure. The avoidability measure figures the degree of how easily a robot can avoid other robots considering the following factors: the distance from the robot to the other robots, velocity of the robot and the other robots. To implement the concept in moving robot avoidance, relative distance between the robots is derived. Our method combines the relative distance with an artificial potential field method. The proposed method is simulated for several cases. The results show that the proposed method steers robots to open space anticipating the approach of other robots. In contrast, the usual potential field method sometimes fails preventing collision or causes hasty motion, because it initiates avoidance motion later than the proposed method. The proposed method can be used to move robots in a robot soccer team to their appropriate position without collision as fast as possible.

• 대한임베디드공학회논문지
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• 제15권2호
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• pp.71-78
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• 2020

This paper proposes vision sensors and deep learning-based around view monitoring system for ship berthing. Ship berthing to the port requires precise relative position and relative speed information between the mooring facility and the ship. For ships of Handysize or higher, the vesselships must be docked with the help of pilots and tugboats. In the case of ships handling dangerous cargo, tug boats push the ship and dock it in the port, using the distance and velocity information receiving from the berthing aid system (BAS). However, the existing BAS is very expensive and there is a limit on the size of the vessel that can be measured. Also, there is a limitation that it is difficult to measure distance and speed when there are obstacles near the port. This paper proposes a relative distance and speed estimation system that can be used as a ship berthing assist system. The proposed system is verified by comparing the performance with the existing laser-based distance and speed measurement system through the field tests at the actual port.

• 동력기계공학회지
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• 제17권5호
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• pp.121-127
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• 2013

In this paper, we propose a distance measurement system for automatic berthing control using a stereo camera mounted on a rotation control device, and a radial pattern target. Automatically controlling the position and attitude of a ship aims to prevent maritime accidents due to human error. Our goal is to measure the relative distance between a ship and an onshore or offshore target for berthing. Therefore, the distance should be continuously measured while tracking a fixed point on a target. To this end, we developed a stereo camerabased distance measurement system that satisfied these requirements. This paper describes the structure and principle of the measurement system. We validate the distance error for target incline due to the relative position and attitude between a camera and a target in miniature scale. In addition, the findings of an experiment in an outdoor environment demonstrate that the proposed measurement system has accuracy within 1 m at a range of 20-100 m which is the acceptable accuracy for automatic berthing.

• 제어로봇시스템학회논문지
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• 제13권10호
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• pp.962-969
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• 2007

In this paper, an approach is developed for relative state estimation of satellite formation flying. To estimate relative states of two satellites, the Extended Kalman Filter Algorithm is adopted with the relative distance and speed between two satellites and attitude of satellite for measurements. Numerical simulations are conducted under two circumstances. The first one presents both chief and deputy satellites are orbiting a circular reference orbit around a perfectly spherical Earth model with no disturbing acceleration, in which the elementary relative orbital motion is taken into account. In reality, however, the Earth is not a perfect sphere, but rather an oblate spheroid, and both satellites are under the effect of $J_2$ geopotential disturbance, which causes the relative distance between two satellites to be on the gradual increase. A near-Earth orbit decays as a result of atmospheric drag. In order to remove the modeling error, the second scenario incorporates the effect of the $J_2$ geopotential force, and the atmospheric drag, and the eccentricity in satellite orbit are also considered.

• 경영정보학연구
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• 제20권3호
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• pp.51-71
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• 2018

많은 정보보호 분야 연구들은 인식을 높여야 할 필요성을 밝히고 있다. 그러나 정보보호에 대한 인식이 상당한 수준으로 높아졌음에도 실제 보호행동은 최근까지 그에 미치지 못하고 있다. 이에 인식수준과는 별개로 정보보호 의사결정에 심리적 요인이 작용할 것으로 가정하고 정보보호에 대한 인식에 차이가 없는 실험상황에서 심리적 거리감과 낙관편향에 따른 차이를 확인하고 정보보호 행동에 대한 영향을 확인하고자 하였다. 연구결과 모바일 기기 사용자의 확률적 거리감에 따라 정보보호 위험의 지각에 차이가 있었으며, 사회적 거리감에 따라 상대적 낙관성의 정도에 차이가 있었다. 이를 바탕으로 상대적 낙관성을 개념화하고 정보보호 행동의도와의 관계를 분석한 결과 자신과 가까운 사람과 비교해 더 낙관적이라 생각했을 때 정보보호 위험의 수준을 낮게 평가하고 확률적 거리감에 따라 영향력이 달라짐을 확인했다. 본 연구는 방법론적 측면에서 의미 있는 시도를 하였고, 정보보호와 관련한 행동에 있어 심리적 요인을 고려함으로써 실질적 위험지각에 영향을 미치는 상대적 낙관성의 범위를 좁혔다는 데 의의가 있다. 정보보호를 위한 의사결정 과정에 다각도로 접근할 필요성을 실증적으로 규명함으로써 궁극적으로 정보기술 사용자의 정보보호 수준 향상과 정보자산의 보호에 기여할 것으로 기대한다.

• ETRI Journal
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• 제45권5호
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• pp.758-767
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• 2023

In this study, we introduce a loosely coupled relative position estimation method that utilizes a decentralized ultrawideband (UWB), Global Navigation Support System and inertial navigation system for flight controllers (FCs). Key obstacles to multidrone collaboration include relative position errors and the absence of communication devices. To address this, we provide an extended Kalman filter-based algorithm and module that correct distance errors by fusing UWB data acquired through random communications. Via simulations, we confirm the feasibility of the algorithm and verify its distance error correction performance according to the amount of communications. Real-world tests confirm the algorithm's effectiveness on FCs and the potential for multidrone collaboration in real environments. This method can be used to correct relative multidrone positions during collaborative transportation and simultaneous localization and mapping applications.

• 대한치과보철학회지
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• 제36권3호
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• pp.496-505
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• 1998

The purpose of this study was to evalute the effect of immersion disinfection on the dimensional stability of rubber impression materials. The metallic master model was made in order to simulate the intraoral arch form. Impressions were made from four impression materials (Exaflex, Extrude, Reprosil, Impregum-F) and immersed in three disinfectant solutions (Wydex, Vi-Pon, Potadine). Casts from the impressions were measured according to the interpreparation distance. The A-B and The B-D abutment distance were compared with the control group and disinfected groups. The results were as follows; 1. The measurements of the stone cast increased relative to the master model and there was a significant difference (P<0.05). 2. The relative dimensional change of the stone cast as compared with master model ranged from 0.10% to 0.56% in the A-B distance and ranged from 0.04% to 0.27% in the B-D distance. 3. The dimensional change of the disinfected groups as compared with the control group was significantly different in the three impression materials except for Impregum-F (P<0.05). 4. The relative dimensional change of the disinfected groups compared with the control group ranged from 0% to 0.20% in the A-B distance and ranged from -0.09% to 0.11% in the B-D distance. These results suggest that immersion disinfection of rubber impression materials by chemical disinfectants causes very small dimensional change and the change is clinically acceptable for prothesis fabrication

• 한국안광학회지
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• 제15권3호
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• pp.257-262
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• 2010

목적: 원용안경의 양안 주시점 이동에 따른 양안시에 미치는 프리즘 굴절력 산출 프로그램 개발. 방법: 델파이 6.0 프로그래밍 언어를 사용하여 원용안경에서 양안 주시점 이동에 따른 상대적인 양안 프리즘 굴절력을 컴퓨터 화면에서 양안 주시점 이동 거리를 마우스로 드래그하여 산출할 수 있는 프로그램을 개발하였다. 결과: 원용안경에서 양안 주시점 이동에 따른 상대적인 양안 프리즘 굴절력을 산출하는 프로그램을 개발하였는데, 마우스 버턴을 이용하여 양안 주시점 궤적을 컴퓨터 화면에 표시하여 주시점 궤적을 확인할 수 있도록 하였으며, 프리즘 굴절력의 변화를 그래프로 확인할 수 있도록하여 사용자가 프로그램을 편리하게 이용하도록 하였다. 결론: 개발되어진 프로그램을 사용하면 사용자들은 원용안경의 양안 주시점의 이동에 따른 상대적인 양안 프리즘 굴절력을 쉽게 계산할 수 있으며 안정피로 해석에 많은 도움을 받을 수 있을 것이다.

• 한국콘텐츠학회논문지
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• 제6권3호
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• pp.102-107
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• 2006

인터넷 원격교육이 보편화되어 가고 있는 현시점에서 인터넷 원격교육의 교육적 효과에 대한 검증은 매우 필요한 연구 대상이라고 할 수 있다. 면대면 교육이 아닌 인터넷 원격교육의 문제점에 대한 분석은 교육적 효과에 대한 검증에서 반드시 거쳐야하는 중요성을 내포하고 있다. 본 연구는 인터넷 원격교육에 참가한 606명의 학생들을 대상으로 한 설문을 바탕으로 인터넷 원격교육의 학습자 입장에서의 문제점에 대한 분석을 실시하였다. 문제점을 환경적 문제, 학생자신의 문제, 교수설계 문제, 운영상의 문제의 4가지 카테고리로 구분하고 카테고리별 문제점들을 도출하여 설문을 통해 문제의 심각성을 분석하였다. 분석 결과는 오늘날의 인터넷 원격교육에 시사하는 점들을 찾을 수 있었다. 또한 각 문제들의 성별, 직업유무, 나이에 따른 차이 유무를 통계적 방법론을 통하여 검증하였다.