• 천문학논총
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• 제22권4호
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• pp.189-199
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• 2007

In this paper, we describe the proposed KVN (Korean VLBI Network) clock system in order to make the observation of the VLBI effectively. In general, the GPS system is widely used for the time information in the single dish observation. In the case of VLBI observation, a very high precise frequency standard is needed to perform the observation in accordance with the observation frequency using the radio telescope with over 100km distance. The objective of the high precise clock system is to insert the time-tagging information to the observed data and to synchronize it with the same clock in overall equipments which used in station. The AHM (Active Hydrogen Maser) and clock system are basically used as a frequency standard equipments at VLBI station. This system is also adopted in KVN. The proposed KVN clock system at each station consists of the AHM, GPS time comparator, standard clock system, time distributor, and frequency standard distributor. The basic experiments were performed to check the AHM system specification and to verify the effectiveness of implemented KVN clock system. In this paper, we briefly introduce the KVN clock system configuration and experimental results.

• 한국컴퓨터정보학회논문지
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• 제22권11호
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• pp.49-55
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• 2017

Recently, for safety of people, there are proposed so many technologies which detect density of people at the specific place or space. The representative technology for crowd density estimation was using image analysis method from CCTV images. However, this method had a weakness which could not be used and which's accuracy was lower at the dark or smog space. Therefore, in this paper, to solve this problem, we proposed a user density estimation system at closed space using high frequency and smart device. The system send inaudible high frequencies to smart devices and it count the smart devices which detect the high frequencies on the space. We tested real-time user density with the proposed system and ten smart devices to evaluate performance. According to the testing results, we confirmed that the proposed system's accuracy was 95% and it was very useful. Thus, because the proposed system could estimate about user density at specific space exactly, it could be useful technology for safety of people and measurement of space use state at indoor space.

• 교육시설
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• 제16권4호
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• pp.79-88
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• 2009

To enhance the administrational efficiency and for university facility and space management to be public, this research suggests a competent and an objective evaluation system and index. The study will assist national and university finances to contribute towards advanced education. Furthermore, figure out the space management condition of national university by utilizing the evaluation system, and through that suggesting efficient special management method. According to the result of this study, evaluation system for university facility can be widely divided into seven categories; system preparation, members conference, propriety of space allocation, propriety of management system, space use ratio, time control of space use, imposition index of surplus use. Based on these subdivisions, the space management category contains 19 evaluation items and the marking system allows perfect score of 100 points. In result of examining space management condition using the evaluation system, space management was well enforced in research focused university group where as in education centered university group, it shows relatively low enforcement. It also illustrated that efforts of evaluation items were required in categories of imposition index of surplus use and special use ratio in order for efficient space management.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.381-385
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• 1992

In this paper, dynamic modeling and adaptive control problems for a space robot system are discussed. The space robot consist of a robot manipulator mounted on a free-floating base where no attitude control is applied. Using an extended robot model, the entire space robot can be viewed as an under-actuated robot system. Based on nonlinear control theory, the extended space robot model can then be decomposed into two subsystems: one is input-output exactly linearizable, and the other is unlinearizable and represents an internal dynamics. With this decomposition, a normal form-augmentation approach and an augmented state-feedback control are proposed to facilitate the design of adaptive control for the space robot system against parameter uncertainty, unknown dynamics and unmodeled payload in space applications. We demonstrate that under certain conditions, the entire space robot can be represented as a full-actuated robot system to avoid the inclusion of internal dynamics. Based on the dynamic model, we propose an adaptive control scheme using Cartesian space representation and demonstrate its validity and design procedure by a simulation study.

• 한국실내디자인학회논문집
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• 제26호
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• pp.42-48
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• 2001

This study is on the relations between space boundary system and spatial effects. The system is consist of circulation axis & territory and vision axis & vision limit. The former is the spatial characteristic and the later is the time one. The purpose of this case study is confirm the correlation of the both and the spatial effect which is caused by space boundary system. Boundary is enable us to cognize 'territory' and intermediary of each territories. The facts that forms space boundary system are circulation axis & territory and vision axis & vision limit. The space boundary system could be categorized by congregation of these facts. and categorizing is determined with agreement degree of each couple of facts. Categorizing facts on the space boundary system are relevant to spatial effect, especially territory, directness, continuity and concentration.

• Journal of Astronomy and Space Sciences
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• 제34권4호
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• pp.303-314
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• 2017

With increased human activity in space, the risk of re-entry and collision between space objects is constantly increasing. Hence, the need for space situational awareness (SSA) programs has been acknowledged by many experienced space agencies. Optical and radar sensors, which enable the surveillance and tracking of space objects, are the most important technical components of SSA systems. In particular, combinations of radar systems and optical sensor networks play an outstanding role in SSA programs. At present, Korea operates the optical wide field patrol network (OWL-Net), the only optical system for tracking space objects. However, due to their dependence on weather conditions and observation time, it is not reasonable to use optical systems alone for SSA initiatives, as they have limited operational availability. Therefore, the strategies for developing radar systems should be considered for an efficient SSA system using currently available technology. The purpose of this paper is to analyze the performance of a radar system in detecting and tracking space objects. With the radar system investigated, the minimum sensitivity is defined as detection of a $1-m^2$ radar cross section (RCS) at an altitude of 2,000 km, with operating frequencies in the L, S, C, X or Ku-band. The results of power budget analysis showed that the maximum detection range of 2,000 km, which includes the low earth orbit (LEO) environment, can be achieved with a transmission power of 900 kW, transmit and receive antenna gains of 40 dB and 43 dB, respectively, a pulse width of 2 ms, and a signal processing gain of 13.3 dB, at a frequency of 1.3 GHz. We defined the key parameters of the radar following a performance analysis of the system. This research can thus provide guidelines for the conceptual design of radar systems for national SSA initiatives.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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• pp.231-234
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• 2004

Electrical grounding is defined as referencing an electrical circuit or a common reference plane for preventing shock hazards and for enhancing operability of the circuit and EMI control. In order to realize the best electrical grounding system of korean space launch vehicle, we should design the electrical grounding architecture of korean space launch vehicle of system-level at the earliest point in design procedure. To minimize the electrical grounding loop and the unnecessary electromagnetic interference or radiation among the electronic subsystems, we should establish the electrical grounding rules of the all electrical interfaces. The electrical interfaces among the electronic subsystems are generally classified into the electrical power and signal interfaces. Because of using the primary and secondary power system architecture in the korean space launch vehicle system such as the common space launch vehicle systems, we need to establish the electrical grounding rules between the primary and secondary power system. We also need to establish the electrical signal grounding interface rules among the electronic subsystems. In this paper, we will describe the grounding schemes of the common space launch vehicle system and propose a conceptual design for the electrical grounding architecture of korean space launch vehicle system.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.27.1-27.1
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• 2008

KASI (Korea Astronomy and Space Science Institute) is developing a compact wide-field survey space telescope system, MIRIS (The Multi-purpose IR Imaging System) to be launched in 2010 as the main payload of the Korea Science and Technology Satellite 3. Through recent System Design Review (SDR) and Preliminary Design Review (PDR), most of the system design concept was reviewed and confirmed. The near IR imaging system adopted short F/2 optics for wide field low resolution observation at wavelength band 0.9~2.0 um minimizing the effect of attitude control system. The mechanical system is composed of a cover, baffle, optics, and detector system using a $256\times256$ Teledyne PICNIC FPA providing a $3.67\times3.67$ degree field of view with a pixel scale of 51.6 arcsec. We designed a support system to minimize heat transfer with Muti-Layer Insulation. The electronics of the MIRIS system is composed of 7 boards including DSP, control, SCIF. Particular attention is being paid to develop mission operation scenario for space observation to minimize IR background radiation from the Earth and Sun. The scientific purpose of MIRIS is to survey the Galactic plane in the emission line of Pa$\alpha$ ($1.88{\mu}m$) and to detect the cosmic infrared background (CIB) radiation. The CIB is being suspected to be originated from the first generation stars of the Universe and we will test this hypothesis by comparing the fluctuations in I (0.9~1.2 um) and H (1.2~2.0 um) bands to search the red shifted Lyman cutoff signature.

• Journal of Astronomy and Space Sciences
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• 제23권4호
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• pp.425-434
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• 2006

한국천문연구원에서 개발 중인 근적외선카메라 KASINICS(KASI Near Infrared Camera System)의 운용을 위한 온도 진공 모니터 시스템을 개발하였다. 이 시스템은 하드웨어 부분과 소프트웨어 부분으로 나누어지며, 온도와 진공도의 측정자료를 실시간으로 PC에서 출력하고 저장할 수 있도록 구성하였다. 이 시스템은 KASINICS와 같은 적외선카메라뿐만 아니라 극저온 냉각을 요하는 모든 장치에 적용할 수 있다. 우리는 KASINICS의 냉각 및 진공 시험을 수행하면서 우리가 개발한 모니터 시스템이 적외선카메라의 시험과 운용에 있어서 효율적이고 안정적이라는 것을 확인할 수 있었다.

• 천문학논총
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• 제21권2호
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• pp.61-66
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• 2006

We have tested the performance of the Proto-model of Space Infrared Cryogenic System (PSICS), which is a small infrared camera, developed by Korea Astronomy and Space science Institute (KASI), Korea Basic Science Institute (KBSI), Korea Institute of Machinery and Materials (KIMM), and i3system co., as a cooperation project. The purpose of PSICS is to ensure a technology of small infrared cryogenic system for future development of space infrared (IR) cameras. PSICS consists of cryogenic part, IR sensor and electronics part, and optical part. The performance test of each part and the integrated system has been completed successfully. PSICS will be used as a guiding camera for ground-based IR telescopes and a test system for developing a space-borne instrument.