• 천문학회보
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• 제43권1호
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• pp.50.2-50.2
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• 2018

국립청소년우주센터 덕흥천문대의 NYSC 1m 망원경은 청소년을 대상으로 관측제안서를 공개모집하고, 청소년의 전문적인 천문관측을 지원하고 있다. 2017년 한 해, 접수된 청소년의 관측제안은 총 10건이었다. 이외에도 덕흥천문대는 양질의 관측자료를 국내 연구팀과의 공동연구를 통해 제공하고 있으며, 공동연구 장기관측과제 3건을 운영 중에 있다. 덕흥천문대 관측팀은 청소년 관측 및 공동연구를 지원하는 것과 더불어 망원경의 상태를 상시 점검하고 있다. 스티커 및 $CO_2$ 분사를 이용한 경면 세척을 진행하였고, 2017년 하반기에는 1m 망원경의 성능을 최대로 발휘할 수 있도록 CCD 카메라를 Princeton Instruments의 SOPHIA 2048B로 교체하였다. 그리고 앞으로 덕흥천문대에서 진행할 향후 운영 계획에 대해서도 논하고자 한다.

• KIEAE Journal
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• 제12권1호
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• pp.3-10
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• 2012

Recently, the increase of impervious area has been pointed out as a major cause of climate change and biotop area deterioration]. Therefore, quantitative indicators for environmental housing design and planning have been needed especially to control the impervious area. The Biotop Area Ratio(BAR) as the mostly applied environmental planning control instrument in Korea verifying the possibility of utilizing has been used effectively in various aspects. However, the fact that the space types are based on two dimension and ecological functions of spaces are simplified has shown the limitations of this planning instrument in the use as planning and evaluation indicator. In this study, classification criteria and the weighting of the space types in similar indicators Biotopflaechenfaktor (BFF, Berlin), Seattle Green Factor (SGF, Seattle), and Green Area Factor (GAF, Malmo) were analyzed. These indicators are similar in the sense that they apply weights to calculate the area and express a percentage of land area. The findings are as follows: The basic method that can estimate the vegetation volume is proposed to overcome the limitation of the BAR. It also was proven that the introduction of three-dimensional volume rate of biotops area was possible. Finally, the framework of space type classification criteria is proposed through linkages with relevant laws and regulations. With the improvement of the space types, the BAR is expected to be reasonable indicator in outdoor space evaluation in housing project.

• Journal of Astronomy and Space Sciences
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• 제38권3호
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• pp.157-164
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• 2021

We describe a method for the in-orbit calibration of body-mounted magnetometers based on the CHAOS-7 geomagnetic field model. The code is designed to find the true calibration parameters autonomously by using only the onboard magnetometer data and the corresponding CHAOS outputs. As the model output and satellite data have different coordinate systems, they are first transformed to a Star Tracker Coordinate (STC). Then, non-linear optimization processes are run to minimize the differences between the CHAOS-7 model and satellite data in the STC. The process finally searches out a suite of calibration parameters that can maximize the model-data agreement. These parameters include the instrument gain, offset, axis orthogonality, and Euler rotation matrices between the magnetometer frame and the STC. To validate the performance of the Python code, we first produce pseudo satellite data by convoluting CHAOS-7 model outputs with a prescribed set of the 'true' calibration parameters. Then, we let the code autonomously undistort the pseudo satellite data through optimization processes, which ultimately track down the initially prescribed calibration parameters. The reconstructed parameters are in good agreement with the prescribed (true) ones, which demonstrates that the code can be used for actual instrument data calibration. This study is performed using Python 3.8.5, NumPy 1.19.2, SciPy 1.6, AstroPy 4.2, SpacePy 0.2.1, and ChaosmagPy 0.5 including the CHAOS-7.6 geomagnetic field model. This code will be utilized for processing NextSat-1 and Small scale magNetospheric and Ionospheric Plasma Experiment (SNIPE) data in the future.

• 천문학논총
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• 제36권2호
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• pp.37-45
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• 2021

We have analyzed 42 research papers regarding on the solar astronomy written by North Korea scientists to investigate the current status of astronomical activities in North Korea. The papers are surveyed from the 'Bulletin of Astronomy', the 'Physics', the 'Bulletin of Academy of Science', and the 'Natural Science' in North Korea, and SCI journals. In addition, we refer to the presentation material announced in the 2015 IAU by director of Pyongyang Astronomical Observatory (PAO) and the 2013 OAD/IAU reports. We have analyzed the papers statistically according to three criteria such as research subject, research field, and research members. The main research subjects are the sunspot (28%), observation system (21%), and space environments (19%). The research fields are distributed with data analysis (50%), numerical method (29%), and instrument development (21%). There have been 25 and 9 researchers in the solar astronomy and space environment, respectively since 1995. North Korea's solar research activities were also investigated in three area: instrument, solar physics, and international research linkage. PAO has operated two of sunspot telescope and solar horizontal telescope for spectroscopy and polarimetry, but there is no specific information on solar radio telescopes. North Korea has cooperated in solar research with Europe and China. We expect that the results of this study will be used as useful resource in supporting astronomical cooperation between South and North Korea in the future.

• 한국전자통신학회논문지
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• 제2권3호
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• pp.143-149
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• 2007

본 발표문에서는 게기착륙시스템이 항공기에 제공하는 유도신호의 기본원리인 공간변조에 대해서 논의함으로써 계기착륙시스템을 심도있게 이해하는데 도움이 되고자 하였다. 우선적으로 공간변조의 기본개념을 설명하였으며, 이와 함께 공간 변조된 신호가 항공기 수신기에 영향을 주어 방위각 및 활공각이 표시되기까지 전반적인 과정을 DDM(difference in depth of modulation) 및 항공기 수신기의 동작원리와 관련시켜 설명하였다.

• 제어로봇시스템학회논문지
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• 제4권6호
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• pp.765-771
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• 1998

An artificial neural network(NN) technique is developed for hardware redundant sensor validation. Since the measurement space is a continuous space with many operating regions, it is difficult to train a NN to correctly detect failure in an accurate measurement system. A conventional backpropagation NN is modified to include an additional preprocessing layer that extracts classification features from scalar measurements. This feature extraction means transform the measurement space to parity space. The NN is independent of the state variable being measured, the instrument range, and the signal tolerance. This NN resembles the parity space approach to signal validation, except that analytical parity equations are unneeded and the NN pattern recognition capability is utilized for decision making.

• 천문학회보
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• 제46권2호
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• pp.59.1-59.1
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• 2021

The Korean spacecraft for the exploration of Apophis will be equipped with an optical navigation camera with a wide-angle lens. The major purpose of the wide-angle camera is to capture imagery during the rendezvous phase in order to determine the spacecraft's position and the pointing direction relative to the asteroid Apophis. Two potential sciences, however, can be achieved by the wide-angle camera: (1) to measure the high-order gravity terms, and (2) to capture possible ejecting small particles. In this presentation, we will discuss instrument specification and operation scenario required to accomplish the given science objectives.

• 천문학회보
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• 제42권1호
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• pp.40.1-40.1
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• 2017

The NISS (Near-infrared Imaging Spectrometer for Star formation history) is the near-infrared spectro-photometric instrument optimized to the Next Generation of small satellite series (NEXTSat). To achieve the major scientific objectives for the study of the cosmic star formation in local and distant universe, the spectro-photometric survey covering more than 100 square degree will be performed. The main observational targets will be nearby galaxies, galaxy clusters, star-forming regions and low background regions. The off-axis optics was developed to cover a wide field of view ($2deg.{\times}2deg.$) as well as the wide wavelength range from 0.95 to $2.5{\mu}m$, which were revised based upon the recent test and evaluation of the NISS instrument. The mechanical structure were tested under the launching condition as well as the space environment. The signal processing from infrared sensor and the communication with the satellite were evaluated after the integration into the satellite. The flight model of the NSS was assembled and integrated into the satellite. To verify operations of the satellite in space, the space environment tests such as the vibration, shock and thermal-vacuum test were performed. The accurate calibration data were obtained in our test facilities. Here, we report the test results of the flight model of the NISS.

• 구강회복응용과학지
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• 제27권1호
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• pp.99-107
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• 2011

비외과적 재근관치료의 주된 목표는 치근주변의 치유를 위하여 근관 공간을 완전히 멸균하는 것이며, 이 목표를 달성하기 위해서는 이전 충전물질의 완전한 제거가 요구된다. 전통적으로 근관충전물질의 제거는 스테인리스스틸 수기구를 통해서 이루어져 왔으며 이는 시간과 노력이 많이 소요되는 작업이다. 최근 보다 효율적인 근관충전물질의 제거를 위해 재치료용 회전식 NiTi 기구가 소개되었다. 이 연구에서는 만곡된 근관에서의 스테인리스스틸 수기구, ProTaper Universal Retreatment (Dentsply Maillefer, Ballaigues, Switzerland), Mtwo retreatment (Sweden & Martina, Padova, Italy)의 gutta-percha 제거 효율을 비교하였다. 재치료 후 근관 내 남겨진 gutta-percha의 양은 실험군 사이에 유의한 차이가 발견되지 않았다. 하지만 재치료에 소요된 시간은 재치료용 회전식 NiTi 기구를 이용한 실험군에서 더 적게 소요되는 것으로 나타났다.

• 천문학회보
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• 제43권2호
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• pp.47.3-47.3
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• 2018

The Korea Astronomy and Space Science Institute (KASI) plans to develop a coronagraph in collaboration with the National Aeronautics and Space Administration (NASA), to be installed on the International Space Station (ISS). It uses multiple filters to obtain simultaneous measurements of electron density, temperature, and velocity within a single instrument. The primary science goal is to understand the physical conditions in the solar wind acceleration region, and the secondary goal is to enable and validate the next generation of space weather science models. The planned launch in 2022 provides great potential for synergy with other solar space missions such as Solar Orbiter and Parker Solar Probe.