• 제목/요약/키워드: solar system

검색결과 4,087건 처리시간 0.031초

Current Status and Results of In-orbit Function, Radiometric Calibration and INR of GOCI-II (Geostationary Ocean Color Imager 2) on Geo-KOMPSAT-2B (정지궤도 해양관측위성(GOCI-II)의 궤도 성능, 복사보정, 영상기하보정 결과 및 상태)

  • Yong, Sang-Soon;Kang, Gm-Sil;Huh, Sungsik;Cha, Sung-Yong
    • Korean Journal of Remote Sensing
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    • 제37권5_2호
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    • pp.1235-1243
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    • 2021
  • Geostationary Ocean Color Imager 2 (GOCI-II) on Geo-KOMPSAT-2 (GK2B)satellite was developed as a mission successor of GOCI on COMS which had been operated for around 10 years since launch in 2010 to observe and monitor ocean color around Korean peninsula. GOCI-II on GK2B was successfully launched in February of 2020 to continue for detection, monitoring, quantification, and prediction of short/long term changes of coastal ocean environment for marine science research and application purpose. GOCI-II had already finished IAC and IOT including early in-orbit calibration and had been handed over to NOSC (National Ocean Satellite Center) in KHOA (Korea Hydrographic and Oceanographic Agency). Radiometric calibration was periodically conducted using on-board solar calibration system in GOCI-II. The final calibrated gain and offset were applied and validated during IOT. And three video parameter sets for one day and 12 video parameter sets for a year was selected and transferred to NOSC for normal operation. Star measurement-based INR (Image Navigation and Registration) navigation filtering and landmark measurement-based image geometric correction were applied to meet the all INR requirements. The GOCI2 INR software was validated through INR IOT. In this paper, status and results of IOT, radiometric calibration and INR of GOCI-II are analysed and described.

Evaluation of Lateral Load Resistance and Heating/Cooling/Lighting Energy Performance of a Post-disaster Refugees Housing Using Lightweight composite Panels (경량 복합패널을 활용한 구호주거의 횡하중 저항성능 및 냉난방조명 에너지성능 평가)

  • Hwang, Moon-Young;Lee, Byung-Yun;Kang, Su-Min;Kim, Sung-Tae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • 제20권3호
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    • pp.252-262
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    • 2019
  • Following the earthquake in Gyeongju (2016) and Pohang (2017), South Korea is no longer a safe place for earthquakes. Accordingly, the need for shelters suitable for disaster environments is increasing. In this study, a lightweight composite panel was used to produce post-disaster housing for refugees to compensate for the disadvantages of existing evacuation facilities. For this purpose, an evaluation of structural performance and thermal environment for post-disaster housing for refugees composed of lightweight composite panels was performed. To assess the structural performance, a lateral loading test was conducted on a system made of lightweight composite panels. The specimens consisted of two types, which differed according to the bonding method, as a variable. In addition, the seismic and wind loads were calculated in accordance with KBC 2016 and compared with the experimental results. Regarding the energy performance, optimization of south-facing window planning and window-wall ratio and solar heat gain coefficient were analyzed to minimize heating, cooling, and lighting energy. As a result, the specimens composed of lightweight composite panels will perform sufficiently safely for lateral loads and the optimized window planning will lead to a low-energy operation.

Deep Learning Based Prediction Method of Long-term Photovoltaic Power Generation Using Meteorological and Seasonal Information (기후 및 계절정보를 이용한 딥러닝 기반의 장기간 태양광 발전량 예측 기법)

  • Lee, Donghun;Kim, Kwanho
    • The Journal of Society for e-Business Studies
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    • 제24권1호
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    • pp.1-16
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    • 2019
  • Recently, since responding to meteorological changes depending on increasing greenhouse gas and electricity demand, the importance prediction of photovoltaic power (PV) is rapidly increasing. In particular, the prediction of PV power generation may help to determine a reasonable price of electricity, and solve the problem addressed such as a system stability and electricity production balance. However, since the dynamic changes of meteorological values such as solar radiation, cloudiness, and temperature, and seasonal changes, the accurate long-term PV power prediction is significantly challenging. Therefore, in this paper, we propose PV power prediction model based on deep learning that can be improved the PV power prediction performance by learning to use meteorological and seasonal information. We evaluate the performances using the proposed model compared to seasonal ARIMA (S-ARIMA) model, which is one of the typical time series methods, and ANN model, which is one hidden layer. As the experiment results using real-world dataset, the proposed model shows the best performance. It means that the proposed model shows positive impact on improving the PV power forecast performance.

Polarimetry of solar system small bodies using the Seoul National University 61cm telescope and TRIPOL

  • Jin, Sunho;Ishiguro, Masateru;Kwon, Yuna Grace;Geem, Jooyeon;Bach, Yoonsoo P.;Seo, Jinguk;Sasago, Hiroshi;Sato, Shuji
    • The Bulletin of The Korean Astronomical Society
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    • 제44권1호
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    • pp.64.2-64.2
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    • 2019
  • It is known that lights scattered by comets and asteroids are partially polarized. From polarimetric observations of those objects, we can investigate physical properties, such as albedos, sizes of cometary dust particles and regolith of asteroids. Since the polarization degrees of those objects highly depend on their phase angles (Sun-object-observer's angles), long-term monitoring observations are required. Moreover, comets show unforeseeable activations (i.e., outbursts) which need follow-up observations to understand the mechanism. In order to realize such monitoring and transient observations, we installed the Triple-Range Imager and POLarimeter (TRIPOL) on the 61cm telescope of Seoul National University (Hereafter, SNU) Gwanak campus. With this combination, we can obtain g', r', i' bands photopolarimetric images simultaneously with $8.0^{\prime}{\times}8.0^{\prime}$ field of view and pixel resolution of 0.94" pixel-1. Here, we make a presentation regarding the photometric and polarimetric performances of TRIPOL on the SNU 61cm telescope. In addition, we introduce initial polarimetric results of asteroid and comets with the instruments. First, we determine the limiting magnitudes (defined as magnitudes for S/N=5) of $15.17{\pm}0.06$ (g'-band), $15.68{\pm}0.01$ (r'-band), $16.24{\pm}0.03$ (I'-band), respectively, with total 240-seconds exposure (four 60-seconds exposure images, each was taken at different rotation angle for the half-wave plate). Second, we found that the instrumental polarization is negligibly small, ($-0.32{\pm}0.04%$ in the g', $-0.36{\pm}0.05%$ in the r' and $-0.21{\pm}0.04%$ in the i'-bands), while the polarization efficiencies are large enough to maximize the performance (i.e., $97.52{\pm}0.03%$ in the g', $98.83{\pm}0.02%$ in the r' and $99.15{\pm}0.02%$ in the i'-bands). With the instruments, we made observations of three Jupiter-family comets, 21P/Giacobini-Zinner, 38P/Stephan-Oterma, and 46P/Wirtanen and plan to observe one near-Earth asteroid, (433) Eros, on a trial basis. Especially for comets, we discriminate signals from dust and gas to eliminate gas contamination, which are known to change observed degree of linear polarization, using multi-band images. We confirm that the phase angle dependency of these comets are consistent with previous observations, probably because polarimetric property of Jupiter-family comets are broadly homogeneous unlike asteroids. We will also describe future observation plans using TRIPOL and SNU 61cm telescope.

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SOMANGNET: SMALL TELESCOPE NETWORK OF KOREA

  • Im, Myungshin;Kim, Yonggi;Lee, Chung-Uk;Lee, Hee-Won;Pak, Soojong;Shim, Hyunjin;Sung, Hyun-Il;Kang, Wonseok;Kim, Taewoo;Heo, Jeong-Eun;Hinse, Tobias C.;Ishiguro, Masateru;Lim, Gu;Ly, Cuc T.K.;Paek, Gregory S.H.;Seo, Jinguk;Yoon, Joh-na;Woo, Jong-Hak;Ahn, Hojae;Cho, Hojin;Choi, Changsu;Han, Jimin;Hwang, Sungyong;Ji, Tae-Geun;Lee, Seong-Kook J.;Lee, Sumin;Lee, Sunwoo;Kim, Changgon;Kim, Dohoon;Kim, Joonho;Kim, Sophia;Jeong, Mankeun;Park, Bomi;Paek, Insu;Kim, Dohyeong;Park, Changbom
    • Journal of The Korean Astronomical Society
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    • 제54권3호
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    • pp.89-102
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    • 2021
  • Even in an era where 8-meter class telescopes are common, small telescopes are considered very valuable research facilities since they are available for rapid follow-up or long term monitoring observations. To maximize the usefulness of small telescopes in Korea, we established the SomangNet, a network of 0.4-1.0 m class optical telescopes operated by Korean institutions, in 2020. Here, we give an overview of the project, describing the current participating telescopes, its scientific scope and operation mode, and the prospects for future activities. SomangNet currently includes 10 telescopes that are located in Australia, USA, and Chile as well as in Korea. The operation of many of these telescopes currently relies on operators, and we plan to upgrade them for remote or robotic operation. The latest SomangNet science projects include monitoring and follow-up observational studies of galaxies, supernovae, active galactic nuclei, symbiotic stars, solar system objects, neutrino/gravitational-wave sources, and exoplanets.

A Study of the Salt Rejection from the Surface of Marine Waste using Ultra Fine Bubble (초미세기포를 이용한 해양쓰레기 표면 내 염분제거에 관한 연구)

  • Kim, Bo-Min;Kim, Kwang-Koo;Park, Chan-Gyu
    • Journal of the Korea Academia-Industrial cooperation Society
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    • 제22권6호
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    • pp.11-18
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    • 2021
  • Nano bubble water is used in various washing processes, including cleaning of solar panels, salt rejection of roads, and cleaning precision parts of machines. High cleaning efficiency and water conservation are obtained by applying nano bubbles during pretreatment of the marine waste cleaning system. This study compared the salt rejection of nano bubble water, and it was revealed that marine waste was produced by wood immersed in 200,000 mg/L NaCl solution. Using tap water and nano bubble water for washing, comparisons of the surface salt concentrations of wood were determined according to the nozzle, orifice diameter, pump speed and washing time. Decreased surface salt concentration was observed on the wood surface with increasing washing time. Water consumption was optimal between 5- and 10-seconds washing time. Increasing orifice diameter of the nozzle reduced the spraying pressure, with consequent increase in the wood surface salt concentration, thereby establishing the importance of orifice diameter of the nozzle. Compared to levels obtained with tap water, salt concentration of the wood surface after washing with nano bubble water was 2.2% lower with sector nozzle, and 30.9% lower with circular nozzle. In the washing experiment using nano bubble water, the salt concentration on the wood surface was about 9.5 mg/L lower when washed with sector nozzle than the circular nozzle.

A Study on Structural Analysis for Improving Driving Performance of Agricultural Electric Car (농업용 전기운반차의 주행성능 향상을 위한 구조해석에 관한 연구)

  • Jo, Jae-Hyun;Lee, Sang-Sik
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • 제13권6호
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    • pp.556-561
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    • 2020
  • The aging and declining agricultural population in the modern society requires improvement of the agricultural environment and is one of the representative problems. And since most of the work systems always require a transport work, the ratio of labor consumed in the transport work is very high. Accordingly, many types of transport vehicles are being developed and sold, and in the early days, most of them are powered transport vehicles using fossil fuels. However, it is paying attention to next-generation eco-friendly energy such as hydrogen, fuel cells, solar power, and bio due to the strengthening of international environmental regulations such as global warming and the Convention on Climate Change and the depletion of fossil fuels. Therefore, in this study, the ultimate goal is to develop an eco-friendly, easy-to-operate, safe agricultural electric vehicle that replaces fossil fuels. It was designed with a focus on controlling a wide range of vehicle speeds and securing stability of electric agricultural vehicles. Considering the performance and design, it is composed of a frame, a driving part, a steering part, and a controller system, and we are going to review and manufacture each part. It is believed that the manufactured electric vehicle for agriculture can be easily and conveniently operated in an agricultural society where young manpower is scarce, and can be helpful to the agricultural society through high efficiency.

Development and Application of Middle School STEAM Program Using Big Data of World Wide Telescope (WWT 빅데이터를 활용한 중학교 STEAM 프로그램 개발 및 적용)

  • You, Samgmi;Kim, Hyoungbum;Kim, Yonggi;Kim, Heoungtae
    • Journal of the Korean Society of Earth Science Education
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    • 제14권1호
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    • pp.33-47
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    • 2021
  • This study developed a big data-based STEAM (Science, Technology, Engineering, Art & Mathematics) program using WWT (World Wide Telescope), focusing on content elements of 'solar system', 'star and universe' in the 2015 revised science curriculum, and in order to find out the effectiveness of the STEAM program, analyzed creative problem solving, STEAM attitude, and STEAM satisfaction by applying it to one middle school 176 students simple random sampled. The results of this study are as follows. First, we developed a program to encourage students to actively and voluntarily participating, utilizing the astronomical data platform WWT. Second, in the paired t-test based on the difference between the pre- and post-scores of the creative problem solving measurement test, significant statistical test results were shown in 'idea adaptation', 'imaging', 'analogy', 'idea production' and 'elaboration' sub-factors except 'attention task' sub-factor (p < .05). Third, in the paired t-test based on the difference between the pre- and post-scores of the STEAM attitude test, significant statistical test results were shown in 'interest', 'communication', 'self-concept', 'self-efficacy' and 'science and engineering career choice' sub-factors except 'consideration' and 'usefulness / value recognition' sub-factors (p < .05). Fourth, in the STEAM satisfaction test conducted after class application, the average values of sub-factors were 3.16~3.90. The results indicated that students' understanding and interest in the science subject improved significantly through the big data-based STEAM program using the WWT.

Design and Development of the SNIPE Bus System (초소형위성 SNIPE 본체 설계 및 개발)

  • Kim, Hae-Dong;Choi, Won-Sub;Kim, Min-Ki;Kim, Jin-Hyung;Kim, KiDuck;Kim, Ji-Seok;Cho, Dong-Hyun;Lee, Jaejin
    • Journal of Space Technology and Applications
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    • 제2권2호
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    • pp.81-103
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    • 2022
  • In this paper, the contents of the design and development process of the 6U micro-satellite Snipe (SNIPE, national name Toyosat; small scale magnetospheric and Ionospheric plasma experiment ), which was developed to observe the near-global space environment through polarization flight for the first time in Korea, were described. Snipe performs transversal flight to observe the Earth's surrounding space environment in three dimensions, and aims to simultaneously observe the space plasma density and temperature in the ionosphere, as well as temporal changes in the solar magnetic field and electromagnetic waves. In this way, it was developed by dividing it into a test certification model (EQM) and a flight model (FM) to perform the actual mission for at least six months, away from developing a cube satellite for short-term space technology verification or manpower training. Currently, Snipe, which has completed the development of a total of four FM and completed all space environment tests, is scheduled to launch 2023. In this paper, we introduce the design contents and development process of the Snipe satellite body ahead of launch, and hope that it will be a useful reference for the development of 6U-class micro-satellite for full-scale mission in Korea.

Effect Analysis of Offshore Wind Farms on VHF band Communications (VHF 대역 통신에 대한 해상풍력 발전단지의 영향성 분석)

  • Oh, Seongwon;Park, Taeyong
    • Journal of the Korean Society of Marine Environment & Safety
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    • 제28권2호
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    • pp.307-313
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    • 2022
  • As the development of renewable energy expands internationally to cope with global warming and climate change, the share of wind power generation has been gradually increasing. Although wind farms can produce electric power for 24 h a day compared to solar power plants, Their interfere with the operation of nearby radars or communication equipment must be analyzed because large-scale wind power turbines are installed. This study analyzed whether a land radio station can receive sufficient signals when a ship sailing outside the offshore wind farm transmits distress signals on the VHF band. Based on the geographic information system digital map around the target area, wind turbine CAD model, and wind farm layout, the area of interest and wind farm were modeled to enable numerical analysis. Among the high frequency analysis techniques suitable for radio wave analysis in a wide area, a dedicated program applying physical optics (PO) and shooting and bouncing ray (SBR) techniques were used. Consequently, the land radio station could receive the electromagnetic field above the threshold of the VHF receiver when a ship outside the offshore wind farm transmitted a distress communication signal. When the line of sight between the ships and the land station are completely blocked, the strength of the received field decreases, but it is still above the threshold. Hence, although a wind farm is a huge complex, a land station can receive the electromagnetic field from the ship's VHF transmitter because the wave length of the VHF band is sufficiently long to have effects such as diffraction or reflection.