• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.61.1-61.1
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• 2021

OWL-Net (Optical Wide-field patroL Network) is the first space situational awareness facility of its kind in South Korea which consists of five identical 0.5 m wide-field telescopes with 4K by 4K CCDs. The five stations are located in Mongolia, Morocco, Israel, United States, and South Korea. They are being operated in fully autonomous mode with the minimum human intervention. The primary objective of OWL-Net is to track Korean domestic satellites. In addition, it can be possible to conduct time-series photometry of bright solar system objects. We will present the system overview of the OWL-Net telescopes and progress report.

• Journal of Arbitration Studies
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• v.33 no.2
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• pp.109-137
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• 2023

This paper reviews legal framework, characteristics and main contents of the 'Optional Rules for the Arbitration of Disputes Relating to Outer Space Activity' enacted by the Permanent Court of Arbitration (PCA) in 2011. Space activities, which began in the 1950s, are undergoing significant changes according to the international characteristics and development of science and technology. New Space and the space business will be the key factors driving these changes. However, the diversity of disputes caused by New Space space activities and the characteristics of each type of dispute must be considered together. This is because the space business can be maintained and developed by securing the effectiveness of dispute resolution. This paper identifies that the PCA Space Dispute Arbitration Rules have important legislative and policy significance in this respect. Specifically, in this paper, the international space law system, the draft convention of the International Law Association, and the PCA arbitration rules were introduced in an overview of the international dispute settlement system related to space activities. Afterwards, it examines that the systematic structure and some major contents of the PCA Space Dispute Arbitration Rules in detail. Based on this, the paper suggests some points of application of the PCA Arbitration Rules and the legislative policy implications.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.3
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• pp.331-339
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• 2016

Real time location (RTL) system which can control the safety of laborers in the underground space is developed in this study. This innovative system can monitor the location and history of movement of multiple laborers in real time. To accommodate constrains of the underground space, the system is portable and composed with low-battery mode. Since conventional method to detect the location of laborer with radio signal strength indicator (RSSI) contains high errors, new measurement system using accelerometers and correction method are suggested in this study. Field test is performed to validate the developed system. The error for moving laborer was 0.4 m and for non-moving laborers was 0.2 m. Thus, it is found that the new RTL system can be used to monitor the location of laborers in the underground construction space.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.75.2-76
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• 2021

MESSIER is a science satellite project to observe the Low Surface Brightness (LSB) sky at UV and optical wavelengths. The wide-field, optical system of MESSIER is optimized minimizing optical aberrations through the use of a Linear Astigmatism Free - Three Mirror System (LAF-TMS) combined with freeform mirrors. One of the key factors in observations of the LSB is the shape and spatial variability of the Point Spread Function (PSF) produced by scatterings and diffraction effects within the optical system and beyond (baffle). To assess the various factors affecting the PSF in this design, we use PhoSim, the Photon simulator, which is a fast photon Monte Carlo code designed to include all these effects, and also atmospheric effects (for ground-based telescopes) and phenomena occurring inside of the sensor. PhoSim provides very realistic simulations results and is suitable for simulations of very weak signals. Before the application to the MESSIER optics system, PhoSim had not been validated for confocal off-axis reflective optics (LAF-TMS). As a verification study for the LAF-TMS design, we apply Phosim sequentially. First, we use a single parabolic mirror system and compare the PSF results of the central field with the results from Zemax, CODE V, and the theoretical Airy pattern. We then test a confocal off-axis Cassegrain system and check PhoSim through cross-validation with CODE V. At the same time, we describe the shapes of the freeform mirrors with XY and Zernike polynomials. Finally, we will analyze the LAF-TMS design for the MESSIER optical system.

• Journal of applied mathematics & informatics
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• v.16 no.1_2
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• pp.461-468
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• 2004

Let W(z) be a power series with operator coefficients such that multiplication by W(z) is contractive in C(z). The overlapping space $L(\varphi)$ of H(W) in C(z) is a Herglotz space with Herglotz function $\varphi(z)$ which satisfies $\varphi(z)+\varphi^＊(z^{-1})=2[1-W^{*}(z^{-1})W(z)]$. The identity ${}_{L(\varphi)}={-}_{H(W)}$ holds for every f(z) in $L(\varphi)$ and for every vector c.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.82.1-82.1
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• 2011

Korea Astronomy and Space Science Institute (KASI) operates 2 solar radio observing facilities, e-CALLISTO (Earthwide network of Compound Astronomical Low-cost Low-frequency Instrument for Transportable Observatory) station and Korean Solar Radio Burst Locator (KSRBL). Although e-CALLISTO tracking system improvement.is underway, at least 6 new events were observed in this year. Software development for KSRBL is in progress. The antenna calibration software was updated and flux calibration software was developed. Also the automatic daily overview spectrum monitoring system is now operational. We found solutions to several problems including spurious data and FPGA board communication. However, a few minor unsolved hardware problems still persist. Meanwhile, at least 6 new events were observed by KSRBL in this year, and a comparative study with HXR is currently underway.

• Journal of Korean Dental Science
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• v.1 no.1
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• pp.22-27
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• 2008

Purpose : This study sought to evaluate the dimensional stability of the SITT (Silicone Index Tooth Tray) impression system and to determine whether providing space for wash impression material in SITT is a necessary step in obtaining accurate prostheses. Materials and methods : After mounting metal dies with shoulder and chamfer margins arbitrarily, SITT was fabricated using Blu-mousse$^{(R)}$. To test the dimensional stability of the SITT system for margin design, the shoulder margin and chamfer margin were evaluated. Furthermore, to test the effect of space for wash impression material, 0.5mm space in SITT and zero space in SITT were statistically compared. Results : 1. There was no significant difference between the group with shoulder margin and that with chamfer margin. 2. There was no significant difference between the group with 0.5mm space and that with zero space for wash impression material. Conclusions : Considering the limitations of this study, the dimensional stability of the SITT system did not interfere with the margin design. Space for the wash impression material was also unnecessary.

• Journal of Astronomy and Space Sciences
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• v.37 no.1
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• pp.11-18
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• 2020

Satellite optical communication has gained significant attention owing to its many quality features (e.g., a larger bandwidth, license free spectrum, higher data rate, and better security) compared to satellite microwave communication. Various experiments have been performed during many space missions to demonstrate and characterize inter-satellite links, downlinks, and uplinks. Korea has also planned to establish an experimental communication system using a geostationary earth orbit (GEO) satellite and the Geochang station as an optical ground station for low Earth orbit (LEO)-to-ground optical relay links. In this study, the performance of inter-satellite communication links and downlinks was investigated for the new Korean experimental communication system in terms of link margin, bit error rate (BER), and channel capacity. In particular, the performance of the inter-satellite links was analyzed based on the receiving apertures and the transmitting power, while that of the downlink was analyzed in terms of atmospheric turbulence conditions and transmitting power. Finally, we discussed two system parameters of receiving aperture and transmitting power to meet the three criteria of link margin, BER, and channel capacity.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.680-684
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• 2005

This paper presents a data-based stability analysis of a MIMO linear time-invariant discrete-time system, as an extension of the previous results for a SISO system. In the MIMO case, a similar discussion as in the case of a SISO system is also applied, except that an augmented input and output space is considered whose dimension is determined in relation to both the orders of the input and output vectors and the numbers of inputs and outputs. As certain subspaces of the input and output space, both output data space and closed-loop data space are defined, which contain all the behaviors of a system, respectively, with zero input in open-loop and with a control input in closed-loop. Then, we can derive the data-based stability conditions, in which the open-loop stability can be checked by using a data matrix whose column vectors span the output data space and the closed-loop stability can also be checked by using a data matrix whose column vectors span the closed-loop data space.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.1
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• pp.18-23
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• 2005

It is difficult to define and classify human emotion. These vague human emotion appear not in single emotion, but in combination of various emotion. And among them, a remarkable emotion is expressed. This paper proposes a emotional expression algorithm using dynamic emotion space, which give facial expression in similar with vague human emotion. While existing avatar express several predefined emotions from database, our emotion expression system can give unlimited various facial expression by expressing emotion based on dynamically changed emotion space. In order to see whether our system practically give complex and various human expression, we perform real implementation and experiment and verify the efficacy of emotional expression system based on dynamic emotion space.