• Journal of Food Hygiene and Safety
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• v.26 no.2
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• pp.171-181
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• 2011

Though food safety efforts of the government has been increasing, but the health hazards resulting from food does not stop and thus increases consumers' anxiety and distrust of government. For more reliable safety management, developing analysis and intake measurement methods and strengthening regulatory control with strict criteria is necessary. In addition, as not only the known hazards by now, but also unknown but obvious hazards are simultaneously ongoing in current environments, the unified risk management and health assessment for food, health food and medicines from the media is critical. As risks and damage to health may show up after a long time after exposure, preventive measures and strategies for safety control is also needed.

• International Journal of Oral Biology
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• v.40 no.4
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• pp.217-221
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• 2015

Cariogenic Streptococcus mutans encounters a variety of host defense factors produced in oral cavity. Nitric oxide (NO) and NO-mediated reactive nitrogen species are potential antimicrobials of innate immunity that can threaten the fitness of S. mutans in their ecological niches. Streptococcal strategies to detoxify cytotoxic NO, which allow S. mutans to persist in caries or other environments of the oral cavity, remain unknown. In this study, we directly measured NO consumption rates of S. mutans isolated in Korea. Surprisingly, all S. mutans strains were unable to consume exogenous NO efficiently, while an intracellular parasite Salmonella enterica serovar Typhimurium expressing the NO-metabolizing enzyme flavohemoglobin consumed most of the NO. This result suggested that S. mutans has alternative detoxification systems for tolerating NO-induced nitrosative stresses.

• Annual Conference of KIPS
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• 2005.05a
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• pp.419-422
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• 2005

본 논문은 미지의 공간 그래프에 대한 실시간 최단 경로 탐색 알고리즘인 $RTA{\ast}$ 알고리즘과 $PHA{\ast}$ 알고리즘을 소개하고, 예제 그래프를 통해 이들의 특성을 설명한다. 또 3차원 온라인 게임 환경인 언리얼 토너먼트(Unreal Tournament) 게임과 Gamebots 시스템을 이용하여 두 알고리즘 간의 탐색 최적성과 효율성을 비교하였다. 이 실험을 통하여 $PHA{\ast}$ 알고리즘은 언제나 최선의 경로를 탐색하지만 이동경로가 많고, 시간이 많이 걸릴 수 있으며, $RTA{\ast}$는 최적의 경로 혹은 차선 경로를 빠른 시간 내에 탐색함을 확인 하였다. 따라서 이러한 특성을 바탕으로 주어진 탐색 환경의 조건에 따라 두 알고리즘을 선택적으로 적용함으로써 보다 높은 효과를 얻을 수 것으로 기대한다.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.183-187
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• 2002

This paper proposes a remote control system that combines computer network and an autonomous mobile robot. We control remotely an autonomous mobile robot with vision via the internet to guide it under unknown environments in the real time. The main feature of this system is that local operators need a World Wide Web browser and a computer connected to the internet communication network and so they can command the robot in a remote location through our Home Page. This system offers an image compression method using motion H.263 concept which reduces large time delay that occurs in network during image transmission.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.45-45
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• 2000

This paper proposes a remote control system that combines computer network and an autonomous mobile robot. We control remotely an autonomous mobile robot with vision via the internet to guide it under unknown environments in the real time. The main feature of this system is that local operators need a World Wide Web browser and a computer connected to the internet communication network and so they can command the robot in a remote location through our Home Page. The hardware architecture of this system consists of an autonomous mobile robot, workstation, and local computers. The software architecture of this system includes the server part for communication between user and robot and the client part for the user interface and a robot control system. The server and client parts are developed using Java language which is suitable to internet application and supports multi-platform. Furthermore, this system offers an image compression method using motion JPEG concept which reduces large time delay that occurs in network during image transmission.

• Proceedings of the IEEK Conference
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• summer
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• pp.52-56
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• 2004

Computing today is becoming ubiquitous. In such ubiquitous computing environments, entities expect to access resources and services at any time from anywhere. Therefore, the question rises of how to establish trust relationship in previously unknown devices or resources with such environment. After reviewing a model to delegate trust to communicating entities in ubiquitous environment and its security problems, we present a new model for secure delegation over communication entities. We adopt two-party signature scheme as cryptographic primitives. Additionally, we apply threshold cryptosystems to our model for more secure enhancement.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.12
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• pp.679-688
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• 2003

In order to navigate the mobile robots safely in unknown environments, many researches have been studied to devise navigational algorithms for the mobile robots. In this paper, we propose a navigational algorithm that consists of an obstacle-avoidance behavior module, a goal-approach behavior module and a radial basis function network(RBFN) supervisor. In the obstacle-avoidance behavior module and goal-approach behavior module, the fuzzy-artificial immune networks are used to select a proper steering angle which makes the autonomous mobile robot(AMR) avoid obstacles and approach the given goal. The RBFN supervisor is employed to combine the obstacle-avoidance behavior and goal-approach behavior for reliable and smooth motion. The outputs of the RBFN are proper combinational weights for the behavior modules and velocity to steer the AMR appropriately. Some simulations and experiments have been conducted to confirm the validity of the proposed navigational algorithm.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.514-516
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• 1998

A Mobile Robot should be able to navigate safely in the workspaces without any additional human's helps. In this paper, a method to generate the safe path to avoid the unknown obstacles using the pre-knowledge of the workspaces was proposed. For the efficiency of the algorithm, it is proposed to model the obstacles as the line segments in numerical map, which can reduce the required memory size and give the simple forms. To make the environments map, we used the Hough transform and the sonar measurements is converted to the set of line segments by Hough transform. In this algorithm, the subgoals are generated to avoid the obstacles until a mobile robot arrives the final position using the proposed environmental model.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.38.1-38.1
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• 2011

Bright rims are one of the most unknown part of a filament nowadays. Many models tried to explain the environments, but there is no commonly acceptable model. Many survey observations have been performed to find various characteristics of the bright rim statistically, but there was only one spectroscopic observation to understand phenomena of the bright rim. We observed a bright rim on June 25, 2010 using FISS installed in NST, Big Bear Solar observatory. FISS can obtain a couple of wavebands data simultaneously with short time cadence and fine resolution(~ 0.1", expected) with Adaptive Optics. By applying the cloud model, we found source function, optical thickness, temperature and non-thermal velocity of the region from the spectra of Ha and CaII 8542 lines. We discuss the physical implication of these measurements on the nature of bright rims of filaments.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2417-2419
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• 2003

이동성에 nonholonomic 제약을 받는 차륜 구동 이동 로봇의 불확실한 환경에서의 자율 주행 제어기를 제안하였다. 전체 시스템은 on-line으로 지역경로 계획을 하는 planner 부분과 차륜 구동 이동 로봇의 nonholonomic 제약을 극복하면서 계획된 지역 경로를 충실히 추종하기 위한 제어기 부분의 두 부분으로 구성하였다. Planner는 빠른 응답을 생성하고, 전역적인 정보를 사용하지 않기 위하여 반사적인 제어 방식에 의한 경로 생성 방식을 채택하였고, 제어기 부분은 비선형 posture feedback stabilizer로 설계하였다. 제안된 시스템은 단순한 형태의 제어 방식으로 완전한 자율적인 판단에 의한 장애물 회피와 목표 지점으로의 수렴 능력을 보여 준다. 본 시스템의 단순하면서도 효과적인 자율주행 능력은 반사제어 방식의 장점과 feedback 제어기의 증명된 안정성에서 기인한다. 시뮬레이션과 자체 구현한 차륜 구동 이동 로봇인 "MARI"로 실제 환경에서의 실험을 실시하여 제안된 제어기의 유효성을 검증하였다.