• 경영과학
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• 제33권4호
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• pp.33-49
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• 2016

The market of platform business is typically served by a few dominant players, presenting "winner-takes-all" phenomenon. This study aims to find service characteristics leading to the phenomenon. Six different service-characteristics were considered : Same-side network effect, cross-side network effects, entry barrier, multi-homing cost, switching cost, and heterogeneity of preference. To assess the degree of concentration of market share, HHI (Herfindahl-Hirschman Index) is calculated for top three major players. Based on the HHI value, 10 most eminent platform businesses are classified into three different segments and each segment is characterized with key factors. The results from this study provide some insight into the strategic management of platform business.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.482-485
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• 1996

We design a homing guidance law based on the proportional navigation for the fast-rolling, single-axis control missiles and analyse the misdistance of the designed guidance system. The guidance law includes a compensation scheme which compensates for the phase-shift between the commanded and achieved acceleration which is peculiar to the fast rolling airframe with single-axis control. In the error analysis of the guidance system, we calculate the misdistance with respect to the target maneuver on the 3-dimensional space via direct simulations. Also, we conduct adjoint simulation on the 2-dimensional plane in case that phase-shift is perfectly compensated. Finally we approximate the linear time-varying dynamics of the missile with autopilot to a linear time-invarient system, and as a result we can find the misdistance as a closed-form.

• 제어로봇시스템학회논문지
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• 제14권8호
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• pp.740-744
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• 2008

In this paper, we propose a new time-to-go estimation filter for PN guided missiles. The proposed estimator is derived based on the approximation of the length of the PNG homing trajectory that we newly introduced using the special coordinate system. The coordinate system is convenient for taking the target movement into account. In addition, compared with the previous time-to-go estimation techniques, the parameters required for evaluating the length can be obtained only with the seeker measurements. Moreover, the seeker measurement error statistics can effectively be considered since our filter is derived based on the Kalman filter theory. Simulation result for a typical anti-ship see-skimming missile homing trajectory shows the excellent performance of the proposed filter.

• 대한임베디드공학회논문지
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• 제5권4호
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• pp.185-194
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• 2010

In this paper, we propose an application layer-based vertical handover management protocol, called multihoming RTP (mhRTP), for real-time applications with seamless mobility across heterogeneous wireless access networks. The proposed multi-homing RTP provides a soft handover by utilizing multiple available wireless access network interfaces simultaneously. The newly available path is dynamically added to the ongoing session by the mhRTP session manager. Also the decision making of QoS-improving or QoS-guaranteed handover is possible based on the estimation of available bandwidth in each candidate network. The performances of the proposed mhRTP have been analyzed through a series of simulations on OPNET network simulator. From the performance analysis, we confirmed that the proposed mhRTP can provide QoS-guaranteed vertical handover with efficient session managements.

• 한국인터넷방송통신학회논문지
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• 제9권6호
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• pp.117-123
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• 2009

본 논문에서는 일반적인 서바이벌특성을 2가지 형태로 분류하여 그 특정을 살펴보고, 네트워크에 이용 가능한 형태를 찾는다. 그리고 이중홈 방식을 이용하여 네트워크 형태에 따른 비용을 분석한다. 또한 서바이벌특성을 가능하게 해주는 네트워크의 물리구조를 최소비용으로 설계할 수 있는 휴리스틱알고리즘을 제안하고 그 결과를 분석하여 실제 네트워크설계에 쉽게 적용할 수 있음을 보인다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.158.5-158
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• 2001

Monopulse active homing radar requires velocity and angle information of target to track fast moving target. Target velocity can be estimated by measuring the frequency shift between transmitted and received frequencies. Angle information is obtained by measuring boresight error. Measurement of doppler frequency component in received signal is done through FFT analysis and interpolation algorithm for fine tuning. Boresight errors in azimuth and elevation axes are proportional to the power of each difference channel relative to sum channel. The target signal power in difference channel is estimated more precisely by measuring the power of FFT result cell of maximum ...

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.469-474
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• 1990

The implementation of modern guidance law derived from optimal control theory requires accurate current states of target, for example, position, velocity and acceleration etc. But there is no sensors that measure the target states directly. So they are estimated from measurable data. For atmospheric missile engagement, direct application of the modern guidance laws may result In deterioration of Intercept performance because of poor observability associated with angles only-measurements by passive seeker and homing geometry. In this paper, a trajectory modulation method called "adaptive Intermittent maneuvers" is added to the modern guidance law, so the observability is enhanced and, consequently, improved the intercept performance. The estimation algorithm called "modified gain pseudo-measurement filter" is used for tracking filter. It is assumed that the passive seeker measure the angles between line of sight and Inertial frame. The Monte-Carlo simulation for realistic air-to-air Intercept scenario are conducted to demonstrate the effectiveness of intermittent maneuvers.ermittent maneuvers.

• 한국군사과학기술학회지
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• 제7권3호
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• pp.30-37
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• 2004

For a proper operation of portable air defense IR terminal homing missile to the rapid intruding target, the boresight of an IR seeker of the missile should be accurately aligned with the gunner's aiming sight. Before a gunner fires the missile, he tries to keep the target within the circle of ASU ensuring the seeker to lock on the target correctly. In this paper, using an electrical seeker caging loop and IR detector signal characteristics, a precise aligning method between the seeker boresight and the LOS(Line of Sight) of ASU(Aiming Sight Unit) was studied. Although every seeker has slightly different SLA (Signal of Look Angle) output, we can get negligible alignment error through a fine tuning method of electrical caging signal. This alignment procedure was also adopted in K-PSAM system.

• 제어로봇시스템학회논문지
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• 제1권1호
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• pp.43-49
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• 1995

본 논문에서는 초음파 센서와 시각 센서에서 얻은 전방향 센서 데이타를 이용하여 실내 이동 로봇용 국부 유도 항법을 위한 새로운 환경 모델링 방법을 제안한다. 그리고 이 두 종류의 센서 데이타에 포함된 불확실성을 주관적 지식과 퍼지 연산법을 사용하여 정량적으로 다룰 수 있는 센서 융합법을 제안한다. 이 방법을 사용하여, 로봇의 현재 위치와 목표 위치간의 기하학적 관계를 더욱 정확하게 얻을 수 있다. 실험 결과를 통하여 제안된 모델링과 센서 융합법이 실내 이동 로봇 항법에 효과적임을 보였다.

• Journal of Information Technology Applications and Management
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• 제13권2호
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• pp.29-39
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• 2006

There has been a tremendous need for dual homing cell switch assignment problems where calling volume and patterns are different at different times of the day. This problem of assigning cells to switches in the planning phase of mobile networks consists in finding an assignment plan which minimizes the communication costs taking into account some constraints such as capacity of switches. This optimization problem is known to be difficult to solve, such that heuristic methods are usually utilized to find good solutions in a reasonable amount of time. In this paper, we propose an evolutionary approach, based on the genetic algorithm paradigm, for solving this problem. Simulation results confirm the appropriateness and effectiveness of this approach which yields solutions of good quality.