• Journal of Space Technology and Applications
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• v.2 no.1
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• pp.1-12
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• 2022

In this paper, we described the development of a drag augmentation device for nanosatellite. Recently, space industry has entered the New Space era, and barriers to entry into Low Earth Orbit (LEO) for artificial objects such as small rockets and nanosatellite mega constellations have been significantly lowered. As a result, the number of space debris is increasing exponentially, and it is approaching as a major threat to satellite currently in operation as well as satellites to be launched in near future. To prevent this, international organizations like Inter-Agency Space Debris Coordination Committee (IADC) have been proposed space debris mitigation guidelines. The Korea Aerospace Research Institute (KARI) conducted KARI Rendezvous & Docking demonstration SATellite (KARDSAT) project, the first nanosatellites for rendezvous and docking technology demonstration in Korea, and we also developed drag augmentation device for KARDSAT Target nanosatellite that complied with the international guideline of post-mission disposal.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.3
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• pp.545-554
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• 2023

In modern industry, the Global Navigation Satellite System(GNSS) is utilized in various fields, where PNT information (P: Positioning, N: Navigation, T: Timing) is always provided and the accurate location estimation based on PNT information is required. In particular, in order to prevent the infection and the spread of the COVID-19 pandemic situation that began in 2019, the precise GNSS technology and various supporting techniques have been used, and, with active quarantine and efforts for the infection spread restrain around the world, we are facing the transition to an endemic situation. In fields of disease and E-health, the location information of users is absolutely necessary to track and monitor infectionous diseases and provide remote medical services, and GNSS plays a leading role in providing the accurate location information. This paper presents investigation results on the up-to-date research trends in which GNSS technologies are employed in the field of disease and E-health, and analyzes the results.

• Journal of Environmental Impact Assessment
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• v.15 no.6
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• pp.443-452
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• 2006

Today, satellite remote sensing (RS) and geographic information systems (GIS) plays an important role as an advanced science and technology. This study was developed a Line Density Algorithm which was clarify and describe the thermal front by using NOAA SST (sea surface temperature) and GIS spatial analysis for systemic and effective management of fish raising industry and sea environmental pollution by land reclamation program. Before this, a study about a interpolation method was carry out which was very important for estimate the hidden value between a special point. For this study Inverse Distance Weighted interpolation, Spline interpolation, Kriging interpolation methods were choose and SST data from 2001 to 2004 in spring (March, April, May) were analyzed. According to the study Kriging interpolation method was the very adaptive method from a practical point of view and excellent in description and precision then others. Finally, the result of this study will be use for develope the Line Density Index Algorism.

• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.29-32
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• 2015

It has been a big trend of the convergence technologies about communication systems and vehicular industry to improve safety and convenience. To achieve a number of infotainment vehicular applications, vehicles should transmit information with high reliability. A robust and accurate channel estimation scheme is of great importance to achieve the goal. In this paper, we present a novel enhanced decision-directed channel estimation scheme called FADP (Frequency Averaging Data Pilot) for dynamic time-varying vehicular channels in IEEE 802.11p. We use linear averaging filtering in frequency domain, and utilize the correlation characteristic of the channels between the adjacent two data symbols, update the CR in time domain to get more accuracy. Finally, analysis and simulation results reveal that compared with exist schemes, the proposed scheme has a good performance in mean square error (MSE) and bit error rate (BER).

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1361-1364
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• 1990

In order to tackle global environmental problems such as destruction of the ozone layer or climatic changes due to atmospheric temperature increase, the acquisition of plentiful and precise data is necessary. Therefore, a means of conducting long-lasting high-resolution measurements over broad areas is required. A feasibility study has been made on a high altitude (20km), super-pressured helium-filled PLTA (Powered Ligher-than-Air) vehicle as an ideal platform for environmental observation. It has a long service life and carries a larger payload than an artificial satellite. This PLTA platform uses an electric propulsion system to maintain position in space against wind currents. The thruster is driven by solar power acquired from solar cells. For night use, solar energy is stored in regenerative fuel cells. This study focuses on energy balance and structural analysis of the hull and platform. The platform is capable of conducting high resolution remote sensing as well as having the capability to serve as a telecommunications relay. The platform could replace a number of ground-based telecommunications relay facilities, guaranteeing sufficient radio frequency intensity to secure good quality telecommunication transmittal. The altitude at which the platform resides has the lowest wind flow in the lower stratosphere, and permits viewing from the ground within a 1,000km range. Because this altitude is much lower than that required of an artificial satellite, the measuring resolution is a couple of thousand times higher than with artificial satellites. The platform can also be used to chase typhoons and observe them from their sources in tropical regions.

• Satellite Communications and Space Industry
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• v.4 no.1
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• pp.81-85
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• 1996

통신기술과 뉴미디어의 발굴로 개인 생활이 편리해지고 지구 전체가 동일 정보영역으로 묶여 하나의 생활권을 형성하는 지구촌 시대가 열리고 있다. 국내에서도 제 1세대 무궁화위성 1.2호의 발사를 계기로 위성시대가 개막되었으며, 인공위성 개발 열기가 한층 고조되고 있다. 그러나 현재 세계적으로 사용하고 있는 위성궤도는 대부분 정지궤도이며, 정지궤도는 한정된 궤도 영역과 위성의 수요증가 때문에 이미 포화상태에 이르러 향후 개발의 한계에 이르게 되었다. 그리고 90년대 초반부터 미국을 중심으로 세계적 규모의 저궤도 위성통신이 제안되기 시작하여 현재 다수의 시스템이 개발되고 있다. 저궤도 위성산업은 이동통신의 세계화와 대중화 추세에 따라 특히 경량 통신위성 시스템을 중심으로 구 수요가 급증할 것으로 예상되고 있으며 이를 통해 통신서비스를 제공하는 국제적 저궤도 위성사업도 활발히 추진되고 있어 앞으로 상업성이 매우 높은 중점 육성대상분야로 평가되고 있다. 현대전자에서 저궤도 위성사업 글로벌스타에 사용될 인공위성을 2005년까지 26기를 제작하여 쏘아 올리겠다고 선언하면서부터 국내의 우주개발 경쟁은 한층 가열되고 있다. 현대전자 산업전자연구소장이자 위성사업단장이신 이명기 전무님으로부터 야심찬 위성사업의 마스터 플랜과 추진현황, 전망 등에 대하여 들어보았다. 사업의 전망을 힘주어 역설하시는 모습이 위성사업에 대한 열정과 도적적 각오를 엿볼 수 있었으며 성공사업으로의 확신을 읽게 하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.4
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• pp.391-397
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• 2016

Vibration disturbances induced by the reaction wheels can severely degrade the performance of high precision payloads on board satellites with high pointing stability requirements. The unwanted disturbances produced by the reaction wheels are composed of fundamental harmonic disturbances due to the flywheel imbalance and sub/higher harmonic disturbances due to bearing irregularities, motor imperfections and so on. Because the wheel speed is constantly changed during the operation of a reaction wheel, the vibration disturbance induced by the reaction wheels can magnify the satellite vibration when the rotating frequency of wheel meets the natural frequency of satellite structure. In order to provide an effective isolation of the reaction wheel disturbances, isolation performance of a hybrid vibration isolator is investigated. In this paper, hybrid vibration isolator that combines passive and active components is developed and its hybrid isolation performance using notch filter control is evaluated in single-axis. The hybrid isolation performance using notch filter control show additional performance improvement compared to the results using only passive components.

• Satellite Communications and Space Industry
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• v.4 no.2
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• pp.84-88
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• 1996

인류가 달에 착륙한 이후 우주개발은 인류에 있어서의 위대한 전진이며 역사적 의의를 지니고 있다. 세계 각국에 우주가 인류의 마지막 보고라는 인식이 커지면서, 최근 우주개발을 둘러싼 세계의 경쟁은 대단히 치열하다. 각종 첨단기술의 결집과 복합응용이 필수인 우주산업을 국내기술로 이루기 위한 노력이 선진국에 비해 결코 적지 않으며 그 뜨거운 열정 또한 우주산업의 미래를 밝게 해 주리라고 믿는다. 항공우주연구소는 우리 나라의 항공.우주과학기술의 개발과 실용화를 위한 중심체 역할을 담당하고 있는 국책연구기관으로서 1989년 10월에 설립되었다. 설립이래, 수많은 업적을 이룩한 바 있으며, 특히 무궁화위성 버스 기술지원사업과 우리별 2호의 우주환경시험 등으로 국내에서는 거의 불모지나 다름없던 위성관련 분야에서 꾸준한 기술축적을 이루어 현재는 위공위성 본체설계 능력을 갖추었으며, 소형위성의 우주환경시험 시설 및 관련기술을 보유하고 있다. 또한 '94년 11월부터 시작되어 현재 추진중인 다목적 실용위성사업은 우리나라 우주기술개발의 새로운 비젼을 제시하는 대형국책사업으로 산.학.연.관의 협력으로 추진되고 있다. 이러한 중요한 시점에 항공우주연구소를 이끌어 나갈 제 4대 소장으로 취임한 장근호 소장으로부터 항공우주산업의 발전을 위한 항우연의 마스터 플랜과 추진현황, 전망 등에 대하여 들어보았다. 열정적으로 대담하시는 모습에서 우주를 향한 우리의 푸른 꿈이 큰 결실을 맺을 것이라는 확신을 가졌다.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.740-745
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• 2023

This study proposes the development of an antenna tracker system using a satellite system to stabilize the communication status of drones and extend the communication distance. The location information of the drone and the ground station was used to maximize communication gain in the general fixed antenna method between the ground station and the drone. We developed a tracker system that can automatically and continuously aim the ground station's antenna at the drone. It is expected that the use of antenna trackers will improve the stabilization of communication conditions and expand the communication distance, thereby leading to the advancement of the drone industry.

• Knowledge Management Research
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• v.16 no.2
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• pp.173-192
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• 2015

Domestic paid broadcasting market is largely classified into cable TV, satellite broadcasting and IPTV. Latest starter IPTV began its commercial service in 2009 and reached 10 million subscribers in August 2014 after 6 years of service. It has been growing rapidly by increasing more than 500 thousand subscribers every quarter and has taken its place firmly as one of core domestic paid broadcasting platforms, second only to cable TV. Even with this quantitative growth, 3 major IPTV companies are still running deficit, attracting attention to issue of the vitalization of IPTV business based on qualitative growth. This study draws out revitalizing and hindering factors of Korean IPTV industry through a case study on 'A' corporation which is leading domestic IPTV market and exploratory study based on interviews with experts and, by developing influencing factors into Causal Loop Diagram through system dynamics research methodology, draws out core issues in vitalization of domestic IPTV industry and suggests alternatives. Therefore, it is expected that this study will provide more diverse practical implications than preceding studies which drew out one-dimensional issues and alternatives and help vitalize Korean IPTV industry by minimizing negative effects and maximizing positive ones.