• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.7
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• pp.508-516
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• 2019

In this paper, we propose a guidance law to control Impact Angle in consideration of look angle limit of the missile with strapdown seeker on the non-maneuvering target. The proposed law is based on sliding mode algorithm and generates acceleration commands using look angle and line of sight information provided by the strapdown seeker and navigation system. And, target velocity and target path angle are provided by like TADS (Target Acquisition and Designation System) at launch time. We can confirm that the target interception and impact angle control are possible through the convergence of the proposed sliding surface. In addition, it is possible to confirm that the sign of derivative result of the look angle at the maximum and minimum look angle is opposite to the sign of the look angle, so the look angle limit is not exceeded.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.2
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• pp.171-176
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• 2007

The tracking antenna must always point to track moving vehicle for data link. In this paper, we determine pointing angle from the geometric relationship of antenna and UAV(Unmaned Aerial Vehicle) to let an antenna be toward a moving vehicle. The pointing angle of antenna is set through GPS measurement data installed in antenna and UAV. We verify the performance of this system from the fixing a camcoder on the antenna.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.237-243
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• 2017

In this paper, the detection performance of the electro-optical telescopes which observes and surveils space objects including artificial satellites, is analyzed. To perform the Modeling & Simulation(M&S) based analysis, satellite orbit model, telescope model, and the atmospheric model are constructed and a detection scenario observing the satellite is organized. Based on the organized scenario, pointing accuracy is analyzed according to the Field of View(FOV), which is one of the key factors of the telescope, considering pointing angle command error. In accordance with the preceding result, detection possibility according to the pixel-count of the detector and the FOV of the telescope is analyzed by discerning detection by Signal-to-Noise Ratio(SNR). The result shows that pointing accuracy increases with larger FOV, whereas the detection probability increases with smaller FOV and higher pixel-count. Therefore, major specification of the telescope such as FOV and pixel-count should be determined considering the result of M&S based analysis performed in this paper and the operational circumstances.

• Journal of the Korea Society for Simulation
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• v.28 no.3
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• pp.75-82
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• 2019

A Satellite Communication (SATCOM), which is applied to various systems to communicate with other systems at the limited wired communication situation, is required to head at a stable point of the space, because this system uses a geostationary satellite. It is important to know satellite tracking heading angles such as elevation angle and azimuth angle for the immovable antenna's latitude, longitude, and altitude. Moreover, calculation of heading angle is critical for SATCOM antenna on a moving platform. In this study, a antenna heading angle calculation method is applied to compute elevation and azimuth angle for a SATCOM antenna and the heading angle simulation is executed for the Korea peninsula and surrounding areas. To verify this simulation, satellite tracking test is conducted using a SATCOM antenna which uses monopulse signal tracking method. The simulation is confirmed by comparing this test result with the simulation. And we make a suggestion for calculation of polarization angle of this antenna.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.884-890
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• 2008

A new guidance law to reach circular target area with grazing angle constraint is proposed as one of midcourse guidance laws of unmanned air vehicles. The purpose of the law is to control the grazing angle between the velocity vector of the vehicle and the line of sight to the aiming point, the center of the circular target area, when the vehicle passes any point on the circle. The optimal solution is derived based on the optimal control theory minimizing a range weighted control energy subject to the nonlinear dynamic equations of the vehicle approaching to the circular target area with grazing angle constraint. The major properties including a convergence of the solution are examined and the performance of the law applied to some typical scenarios is shown by the numerical simulation.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.357-360
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• 2005

본 연구는 소스 코드를 재사용하기 위한 Case 기반 검색에 있어서 효율적인 검색 시스템을 구축하는 방법을 제안하고자 한다. 소스 코드의 객체지향적인 특성을 만족하기 위하여 각 노드 간 객체지향 상속의 개념을 표현할 수 있도록 초기 관련값을 시소러스로 구축하고자 한다. 이때, 각 Case를 구성하는 클래스들을 상속관계에 따라 개념적으로 분류하였고, 시소러스 방법에 퍼지 논리를 적용하여 객체지향 시소러스를 생성하여 의미망을 구축한다. 또한, 의미망의 노드와 간선을 활성화시키고 활성값을 전파시키기 위해 사용되는 spreading activation 방법의 단점을 보완하여 spreading activation의 성능은 최대한 유지하면서 검색 속도를 향상시킬 수 있는 방법을 제안하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9B
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• pp.1189-1195
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• 2001

본 연구에서는 수평면에 대해서 양방향성을 갖고 접지면을 향해서 주빔이 25$^{\circ}$의 기울기로 지향하도록 설계된 대칭 SSAIP(Strip, Air, Inverted Patch) 구조의 슬롯 결합 back-to-back 마이크로스트립 위생배열 안테나를 설계, 제작하였다. 이 구조의 안테나는 2-섹터 셀 사이트에서 기지국 또는 중계기의 지향성 안테나에 적용할 수 있으며, 도로 환경에 따라 지향각 25$^{\circ}$를 기준으로 약 $\pm$$10^{\circ}$정도 빔을 틸트할 수 있도록 위상기와 결합된다. 안테나는 공동모델을 이용하여 해석하고 앙상블로 설계한다. IMT-2000의 상.하향 링크 주파수 범위인 1.885~2.2GHz에서 안테나를 측정한 결과 임피던스 대역폭은 약 21%이였으며, $\pm$37$^{\circ}$의 지향각 오차를 보였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.347-350
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• 2012

The researches on driver assistance systems that can prevent an accident have been actively performed due to social issues of traffic accidents with development of vehicle industry in recent. It is required for researchers to develope systems which assist driver's perception and judgment when considering that over 70% of traffic accidents occur by drivers' carelessness and 75% of the total accidents occur at the speed of less 29km per hour. In this paper, we implemented a front and rear vehicle monitoring system that monitors distance in real-time from a vehicle to obstacles at the low-speed or back-ward driving. The implemented system consists of a high angle ultrasonic sensor with distance detection of 10m and 10-degree angle, a wide angle ultrasonic sensor with the detection distance of 3m and a 180-degree, and a ATmega128 chip of ATmel company.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.72-78
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• 1981

The purpose of this study is to find directivity characteristics and relative gain of directivity of the wedge horn in conjunction with a projector with varing horn length, horn angle and frequency. The horns are constructed with aluminum plate covered with styrofoam. By using hinges the horn angle could be varied with wide range. Measurements were made over the frequency range of 25 KHz-100 KHz by varing the horn lengths from 5cm to 21cm and the horn angles up to 90 degrees. The followings were the results obtained from the study, 1. As the horn angle increased, the beam width for tile major lobe initially decreased and then increased. At 80 KHz with horn length 21cm the minimum beam widths were obtained with 16 degrees in horizontal plane and 36 degrees in vertical plane. 2. The maximum relative gains of directivity were 4.4 dB in horizontal plane and 3.4 dB in vertical plane when the horn length was 21cm. 3. Beam width was decreased with increasing of frequency. 4. When the mouth apertures were small the major lobes obtained by the experiment agreed with the computed ones, and when the mouth apertures were wide the major lobes by the observed were wide than the computed ones.

• Proceedings of the Korea Association of Information Systems Conference
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• 1997.10a
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• pp.413-425
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• 1997

실시간 시스템(realtime system)은 외부환경에서 보내진 요구사항(requirement)에 정해진 시간 내에 반응(action)해야만 한다. 시스템의 외부환경은 실세계(real world)의 물리 적인 요소(physical element)가 되며 이러한 물리적인 요소는 객체지향 설계 (object-oriented design) 개념에서 객체(object)이다. 또한 시스템을 설계하는 경우는 객체 지향 방법론을 적용함으로서 보다 명확한 표현이 가능하게 되며 실세계의 물리적인 각 요소 가 부품단위(component units)로 동작하는 형태를 소프트웨어로 설계하는 것이 용이하게 된다. 따라서 본 논문에서는 실시간 시스템설계에서 객체지향 방법을 사용하고, 원시 (source) 소프트웨어의 분석(analysis)과 검증(verification) 및 흐름(flow)를 슬라이스 기법을 사용하여 표현함으로써 시스템의 전체적인 구성을 명확하게 표현하며 클래스(class) 단위로 슬라이스 된 각 부분으로 상속(inheritance)과 메시지 전달(message sending)의 흐름을 파 악할 수가 있다. 그리고, 보다 효율적인 시스템의 외부환경의 오동작 처리 및 시스템 흐름 을 감시 추적(monitoring and tracing)할 수 있도록 슬라이싱 맵을 데이터베이스로 구축하 여 활용하는 방법을 제시한다. 또한 슬라이싱 맵 표현 방벙에 있어서 기존의 표현을 보다 구체적이고 실제적인 표현기호를 제시한다.