• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.12
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• pp.1124-1132
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• 2011

This paper deals with smooth path generation using B-spline for fixed-wing unmanned aerial vehicles manuevering in 2D environment. Hexagonal cell representation is employed to model the 2D environment, which features increased connectivity among cells over square cell representation. Subsequently, hexagonal cell representation enables smoother path generation based on a discrete sequence of path from the path planner. In addition, we present an on-line path smoothing algorithm incorporating B-spline path templates. The path templates are computed off-line by taking into account all possible path sequences within finite horizon. During on-line implementation, the B-spline curves from the templates are stitched together repeatedly to come up with a reference trajectory for UAVs. This method is an effective way of generating smooth path with reduced on-line computation requirement, hence it can be implemented on a small low-cost autopilot that has limited computational resources.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.594-600
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• 2016

The present study numerically investigated the gas leakage characteristics in a simplified underground combined cycle power plant. The effect of obstacles near a crack location on the gas concentration in the confined space was analyzed by using the lower flammable limit (LFL) of methane gas. When the jet flow was close to the vertical walls, the longitudinal leakage distance increased by about 60% (when an obstacles was present) compared to the case without any obstacle, because these obstacles prevented transverse flows. In addition, when an air filter was installed near to the trajectory of the gas flow, the longitudinal leakage distance was similar to the distance between the crack and obstacle, whereas the transverse leakage distance increased up to 8 times compared to the case without any obstacle. As the jet flow impacts on the obstacle and changes its direction, the gas flows recirculate. Therefore, it is necessary to consider the effect of the structure and facility locations on the trajectory of the jet flow to propose an accident prevention system in confined spaces.

• The Transactions of the Korea Information Processing Society
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• v.6 no.12
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• pp.3710-3717
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• 1999

For the development of unmanned autonomous vehicle, it is essential to detect obstacles, especially vehicles, in the forward direction of navigation. In order to reliably exclude regions that do not contain obstacles and save a considerable amount of computational effort, it is often necessary to confine computation only to ROI(region of interest)s. A ROI is usually chosen as the interior region of the lane. We propose a computationally simple and efficient method for the detection of lanes based on Hough transform and quadratic curve fitting. The proposed method first employs Hough transform to get approximate locations of lanes, and then applies quadratic curve fitting to the locations computed by Hough transform. We have experimented the proposed method on real outdoor road scene. Experimental results show that our method gives accurate detection of straight and curve lanes, and is computationally very efficient.

• The Korean Journal of Air & Space Law and Policy
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• v.19 no.1
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• pp.79-107
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• 2004

Shielding theory is to allow the construction of a structure that would be shielded by existing permanent structures even thought such structure extends above the height limits prescribed for such zones. This theory is mentioned as recommended practices in ICAO Annex, and is adopted, with modification, in the current Military Airbase Law, amended in August 26th 2002. However, the Military Airbase Law adopts shielding standard allowing 45 meters uniformly, which is a unique standard compared to other countries shielding guideline. The basic principle in applying the shielding theory is, after considering the circumstances of location of shielded structure, whether such structure has physical effect on aeronautical operations. Based upon the basic principle of shielding theory, the uniform application of shielding standard in the Military Airbase Law would undermine the safety of aeronautical operations. This article is to review subsection 2 of section 8 of the Military Airbase Law, which adopts modified shielding theory, and is to suggest better guideline. From a comparative analysis perspective, shielding guidelines of ICAO and other countries will be discussed. Based upon this discussion, the general problems of shielding theory and the specific problems in the Military Airbase Law will be examined. Finally, this article suggests the case-by-case application of shielding theory, considering circumstances of location, for the purpose of ensuring aviation safety.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.110-112
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• 2015

지상파 디지털멀티미디어방송(T-DMB)을 이용하여 국지적인 재난경보 방송을 실시하고 있지만 산간오지 등과 같은 전파 음영 지역에는 시설 투자의 한계로 서비스가 제한되고 있는 실정이다. 무선 마을 방송 시스템은 ISM 밴드 주파수를 사용하고 있으며 마을 방송용으로 주파수를 제한하여 간섭영향이 상대적으로 적은 장점을 갖는다. 본 논문에서는 T-DMB 재난 방송을 기존 무선 마을 방송 시스템의 장점을 이용하여 산간오지의 댁내까지 방송 가능한 시스템을 제안하였다. 재난 발생시 T-DMB 특수 수신기의 재난 방송 출력 신호를 무선 마을 방송 송신기와 복수의 댁내 무선 수신기를 통하여 방송 가능한 구조이며 T-DMB 수신기와 무선 방송 송신기간에는 접점 인터페이스를 통하여 정확한 시퀀스 제어가 필요하다. 무선 마을 방송 시스템은 UHF 대역의 ISM 밴드 무선 주파수를 이용하여 오지산간 지역의 부락에 적합한 특성을 갖고 있다. 장애물로 인한 장거리 전송의 한계는 무선 중계기를 이용하여 커버리지를 확장 가능하다. 따라서, 본 논문에서는 T-DMB 재난 방송을 재송신하는 수단으로 ISM 밴드와 연동할 경우 방송 음영지역 해소 및 재난 방송 수신율이 개선되어 국지적 재난에 대한 대국민 인명과 재산보호에 기여할 것으로 판단된다.

• The KIPS Transactions:PartB
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• v.8B no.6
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• pp.705-717
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• 2001

In this paper, we propose a rapid lane detection method to extract a preceding vehicle from sequential images captured by a single monocular CCD camera. We detect positions of lanes for an individual image within the limited area that would not be hidden and thereby compute the slopes of the detected lanes. Then we find a search area where vehicles would exist and extract the position of the preceding vehicle within the area with edge component by applying a structured method. To verify the effects of the proposed method, we capture the road images with a notebook PC and a CCD camera for PC and present the results such as processing time for lane detection, accuracy and vehicles detection against the images.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.11
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• pp.73-82
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• 2003

In this paper, a simultaneous buffer insertion and routing method is proposed under the constraints of wire and buffer locations by macro or IP blocks. A new grid graph is proposed to describe the regions in which buffers(or both wires and buffers) are not available. Under this grid we describe a method of constructing a buffeted tree that minimize the maximum source to sink delay. The method is based on the dynamic programming with pruning unnecessary partial solutions. The proposed method improved the slack time of the delay by 19% on the average while using less buffers and similar wire length.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.413-421
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• 2010

In the study, self-organization by color detection is proposed to overcome required constraints for existing self-organization by an external ceiling camera and communication. In the proposed self-organization, each swarm robot can follow its colleague robot and all swarm robots can follow a target by LOS(Line of Sight). The swarm robots follow the moving target by the proposed potential field, avoiding confliction with neighboring robots and obstacles. Finally, all swarm robots are reached by a sight among swarm robots. In this paper, for unicycle robots with non-holonomic constraints instead of point robot with holonomic constraints self-organization is presented, it enhances the possibility of H/W realization.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.01a
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• pp.199-200
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• 2021

최근 어린이 보호구역 내에서의 운전자의 부주의로 사망 혹은 상해 사고를 일으킨 가해자를 가중 처벌하는 내용의 '민식이법'이 발의됨에 따라 많은 운전자들이 보호구역을 주행할 때 많은 부담감을 느끼며, 이에 대한 운전자의 부담감과 사고 피해를 최소화할 수 있는 시스템이 필요하다. 본 논문에서는 OpenCV 영상인식기술과 OCR 문자인식기술인 Tesseract를 이용해 노약자 보호구역 표지판을 인식하여 법정 제한속도를 준수하며 갑작스러운 장애물 등장 시 급정거하여 사고피해를 최소화하고, 또한, 사용자에게 알람 메시지를 전송하는 시스템을 제안한다.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.105-108
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• 2003

A ultrasonic alert system is proposed in order to prevent the collision accidents of srmll ships. This system displays a lamp and a sound signal alerting collision by trrmsmitting ultrasonic pulse in air to detect ships and objects within fXJ m Under the condition of restricted visibility and compliazted works, it is expected to enh:uu:e the effect if navigators' lookout.