• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2420-2423
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• 2001

본 논문에서는 Nonholonomic 특성을 갖는 이동로봇이 여러 가지 장애물이 있는 환경 하에서 장애물들을 회피하면서 목표지점에 표시된 표식을 인식하고, 그 표식에 대해 일정한 자세를 유지하면서 목표 지점으로 이동하는 Homing 동작을 행위 기반 제어 알고리즘을 기반으로 한 개선된 주행알고리즘을 제안한다. 또한 장애물이 있는 환경에서의 이동로봇이 Homing하는 모의실험을 통해 제안한 알고리즘의 성능을 검증하였다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 The Third Asian Fuzzy Systems Symposium
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• pp.170-175
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• 1998

Transporting a large table using multiple robotic agents requires at least two group behaviors of homing and herding which are to bo coordinated in a proper sequence. Existing GP methods for multi-agent learning are not practical enough to find an optimal solution in this domain. To evolve this kind of complex cooperative behavior we use a novel method called fitness switching. This method maintains a pool of basis fitness functions each of which corresponds to a primitive group behavior. The basis functions are then progressively combined into more complex fitness functions to co-evolve more complex behavior. The performance of the presented method is compared with that of two conventional methods. Experimental results show that coevolutionary fitness switching provides an effective mechanism for evolving complex emergent behavior which may not be solved by simple genetic programming.

• Smart Structures and Systems
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• 제8권1호
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• pp.39-52
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• 2011

We are developing a biomimetic robot based on the Sea Lamprey. The robot consists of a cylindrical electronics bay propelled by an undulatory body axis. Shape memory alloy (SMA) actuators generate propagating flexion waves in five undulatory segments of a polyurethane strip. The behavior of the robot is controlled by an electronic nervous system (ENS) composed of networks of discrete-time map-based neurons and synapses that execute on a digital signal processing chip. Motor neuron action potentials gate power transistors that apply current to the SMA actuators. The ENS consists of a set of segmental central pattern generators (CPGs), modulated by layered command and coordinating neuron networks, that integrate input from exteroceptive sensors including a compass, accelerometers, inclinometers and a short baseline sonar array (SBA). The CPGs instantiate the 3-element hemi-segmental network model established from physiological studies. Anterior and posterior propagating pathways between CPGs mediate intersegmental coordination to generate flexion waves for forward and backward swimming. The command network mediates layered exteroceptive reflexes for homing, primary orientation, and impediment compensation. The SBA allows homing on a sonar beacon by indicating deviations in azimuth and inclination. Inclinometers actuate a bending segment between the hull and undulator to allow climb and dive. Accelerometers can distinguish collisions from impediment to allow compensatory reflexes. Modulatory commands mediate speed control and turning. A SBA communications interface is being developed to allow supervised reactive autonomy.

• 한국IT서비스학회지
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• 제10권2호
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• pp.75-94
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• 2011

The industrial ecosystem around the Internet services has been evolving since the Internet was first introduced. The Net Neutrality issue best represents the process of the evolution and presents an inevitable challenge that the industry should overcome. This paper deals with this structural change with the Two-Sided Market framework and provides a System Dynamics(SD) model to evaluate the economic implications of the net neutrality policy. In particular, our approach analyzes the policy impacts when two competing platforms (network providers) play a role of the platform in a typical two-sided market, which connects Content Providers(CPs) with users. Previous studies show that the indirect network externality between these two markets makes the entire system tip to one platform. When the multi-homing in the CP market is allowed as in our model, however, their argument may lose its validity. To examine the system behavior, conducted here is SD simulations of our model. The simulation results show that co-existence of the competing platforms persists with the network effects over a certain threshold. The net neutrality policy seems to lower the threshold based on our experimental outcomes.

• 환경영향평가
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• 제18권3호
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• pp.123-129
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• 2009

In Korea the population of breeding house swallow is continuously decreasing. In this regard this study was conducted to find out the overall population trend during 2001-2005. The areas of urban and rural sites were separated to estimate population. Also the sites in Yangpyung areas were chosen to compare population density between two sites during Mar-Aug, 2006. The house swallow had two breeding periods and I tried to correlated amount of days of incubation and number of eggs in the nest. After egg hatching the homing behavior also was estimated assuming lack of foods takes longer to bring foods back to the nest. This study signified that a long term study should be conducted for population change and spring arrival time due to climate change in Korea.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1736-1737
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• 2011

This paper deals with the problem of precise impact angle control of an actual homing missile guided by biased proportional navigation (BPN). To do this, the BPN guidance loop including dynamic lag is modeled as the confluent hyper-geometric differential equation and its analytic solution is derived. Based on the solution, a systematic way to determine the bias constant is newly devised. Different from the existing BPN solution obtained by ignoring the dynamic lag, the proposed one can exactly describe the behavior missile before target interception. hence it is drastically improved the angle constrained terminal guidance performance.

• International Journal of Control, Automation, and Systems
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• 제2권3호
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• pp.333-342
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• 2004

This paper presents a framework for the self-organization of swarm systems based on coupled nonlinear oscillators (CNOs). In this scheme, multiple agents in a swarm self-organize to flock and arrange themselves as a group using CNOs, which are able to keep a certain distance by the attractive and repulsive forces among different agents. A theoretical approach of flocking behavior by CNOs and a design guideline of CNO parameters are proposed. Finally, the formation scenario for cooperative multi-agent groups is investigated to demonstrate group behaviors such as aggregation, migration, homing and so on. The task for each group in this scenario is to perform a series of processes such as gathering into a whole group or splitting into two groups, and then to return to the base while avoiding collision with agents in different groups and maintaining the formation of each group.

• 전자통신동향분석
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• 제33권2호
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• pp.64-76
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• 2018

This paper addresses the antitrust case of Google's general search service to find evidence and logic used for defining markets, and the proof of dominant power and its abuse in detail. This antitrust case has certain meaning because it is not easy to apply traditional approaches to a general search service, which has two-sided market characteristics. This paper finds some implications through an analysis of the antitrust case shown below. First, for market definition, the overall qualitative analysis can be used to draw conclusions without a quantitative analysis, such as a Small but Significant and Non-transitory Increasing in Price (SSNIP) analysis. Second, the multi-homing behavior seems to be one of the key factors in judging the dominant power in Internet-based services. Lastly, the fact that the value of traffic can differ based on the traffic source needs to be considered to address the competition issue of Internet-based services.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• 제3권4호
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• pp.199-203
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• 2022

The spring home range and habitat use of the spot-billed duck in Korea were studied using GPS-mobile phone-based telemetry (WT-300). The study areas were Anseong-si, Seosan-si, Nonsan-si, and Sejong-si. Analysis was performed using minimum convex polygon (MCP) and kernel density estimation (KDE) spot-billed ducks had an average home range of 70.28 km² (standard deviation [SD]=84.50, n=6), and a core habitat (50%) 2.66 km² (SD=2.60, n=6), according to MCP and KDE, respectively. Wetlands (41.5%) and rice fields (35.7%) were highly used as habitats. The rice field use rate was high during the day, and the wetland utilization rate was high at night. Rice fields and wetlands were the primary habitats in spring.

• 한국화재소방학회논문지
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• 제18권3호
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• pp.39-44
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• 2004

Pool화재의 화염 거동을 알아보기 위하여 산업에서 많이 사용되는 가연성 액체인 아세톤 메탄을 헥산 그리고 헵탄을 직경 50mrn에서 400nun까지의 용기 내에 넣고 연소실험을 하였다. 용기의 재질은 스테인리스와 구리를 사용하였다. 연소시간과 용기 벽면의 온도 및 열유속 등을 측정하였으며 연소 시 화염의 거동은 비디오카메라를 이용하여 촬영하였다. 실험을 통해서 연소속도와 화염의 높이는 용기 직경의 증가와 함께 증가하였으며 화염의 와류 생성 주기는 용기 직경에 반비례하였다. 또한 pool화재의 특성은 액체연료의 물리 화학적 성질과 용기의 재질에 의해서도 영향을 받는 것을 알 수 있었다.