A5009153812- Space Satellite Systems and Control
- Astro and Planetary Science
- Inertial Sensor and Navigation
- Planetary Science and Exploration
- Space exploration and regulation
- GNSS positioning and interference
- Astronomical Observations and Instrumentation
- Nanoparticle-Based Drug Delivery
- Ionosphere and magnetosphere dynamics
- Conducting polymers and applications
- Geophysics and Gravity Measurements
- Quantum Dots Synthesis And Properties
- Optical Systems and Laser Technology
- Space Exploration and Technology
- Characterization and Applications of Magnetic Nanoparticles
- Advanced Optical Sensing Technologies
- Astronomy and Astrophysical Research
- Magnetic Properties and Synthesis of Ferrites
- Electrospun Nanofibers in Biomedical Applications
- Fuel Cells and Related Materials
- Stellar, planetary, and galactic studies
- RFID technology advancements
- Infrared Target Detection Methodologies
- Time Series Analysis and Forecasting
- Pigment Synthesis and Properties
Korea Astronomy and Space Science Institute
2015-2022
Korea Advanced Institute of Science and Technology
2022
Chungnam National University
2011-2012
The key risk analysis technologies for the re-entry of space objects into Earth’s atmosphere are divided four categories: cataloguing and databases objects, lifetime trajectory predictions, break-up models after multiple debris distribution ground impact probability models. In this study, we focused on reentry prediction, including orbital assessments, situational awareness systems. Re-entry predictions very difficult affected by various sources uncertainty. particular, during uncontrolled...
An Optical Wide-field patroL-Network (OWL-Net) has been developed for maintaining Korean low Earth orbit (LEO) satellites' orbital ephemeris. The OWL-Net consists of five optical tracking stations. Brightness signals reflected sunlight the targets were detected by a charged coupled device (CCD). A chopper system was adopted fast astrometric data sampling, maximum 50 Hz, within short observation time. accuracy validated with precise ephemeris such as Consolidated Prediction File (CPF) and...
With increased human activity in space, the risk of re-entry and collision between space objects is constantly increasing. Hence, need for situational awareness (SSA) programs has been acknowledged by many experienced agencies. Optical radar sensors, which enable surveillance tracking objects, are most important technical components SSA systems. In particular, combinations systems optical sensor networks play an outstanding role programs. At present, Korea operates wide field patrol network...
본 논문에서는 기계학습과 관련된 다양한 사례들에 대한 연구를 바탕으로 기계학습 응용 및 학습 알고리즘의 성능 개선 방안을 제시한다. 이를 위해 기법을 적용하여 결과를 얻어낸 문헌을 자료로 수집하고 학문분야로 나누어 각 분야에서 적합한 선택 추천하였다. 공학에서는 SVM, 의학에서는 의사결정나무, 그 외 분야에서는 SVM이 빈번한 이용 사례와 분류/예측의 측면에서 효용성을 보였다. 기계학습의 적용 사례분석을 통해 방안의 일반적 특성화를 꾀할 수 있었다. 단계는 크게 3단계로 이루어진다. 첫째, 데이터 수집, 둘째, 알고리즘을 통한 학습, 셋째, 알고리즘에 유의미성 테스트 이며, 단계에서의 결합을 성능을 향상시킨다. 향상의 방법은 다중 구조 모델링과 <TEX>$+{\alpha}$</TEX> 모델링 등으로 분류한다. This paper aims to present the way bring about significant results through performance...
The Accurate Ranging System for Geodetic Observation - Mobile (ARGO-M) was successfully developed as the first Korean mobile Satellite Laser (SLR) system in 2012, and has joined International Service (ILRS) tracking network, DAEdeoK (DAEK) station. DAEK SLR station approved a validated April 2014, through ILRS "data validation" process. ARGO-M is designed to enable 2 kHz laser ranging with millimeter-level precision geodetic, remote sensing, navigation, experimental satellites equipped...
The first Korean satellite laser ranging (SLR) system, Daedeok SLR station (DAEK station) was developed by Korea Astronomy and Space Science Institute (KASI) in 2012, whose main objectives are space geodesy researches. In consequence, became the <TEX>$25^{th}$</TEX> country that operates system supplementing international tracking network. DAEK is designed to be capable of 2 kHz with precision a few mm both daytime nighttime observation satellites retro-reflector array (LRA) up altitude...
Inactive space objects are usually rotating and tumbling as a result of internal or external forces. KOREASAT 1 has been inactive since 2005, its drift trajectory monitored with the optical wide-field patrol network (OWL-Net). However, quantitative analysis in regard to attitude evolution never performed. Here, two tracking systems were used acquire raw measurements analyze rotation period satellites. During campaign 2013, was observed by 0.6 m class telescope operated Korea Astronomy Space...
한국천문연구원은 인공위성 정밀궤도 결정, 우주측지 및 자세역학 연구를 위해서 2kHz 반복율을 가지는 SLR 시스템을 운영하고 있다. 그러나 측지위성의 회전속도를 보다 정밀히 결정하고 거리 측정 정밀도 향상을 고반복율의 관측 데이터가 요구된다. 따라서 고반복율 시스템 구현을 위해 운영 소프트웨어 레인지 게이트 생성기를 개발하여 최대 10kHz 반복율로 레이저추적이 가능한 HSLR-10(High repetition-rate Satellite Laser Ranging-10kHz) 시스템으로 개선하였다. 본 연구에서는 HSLR-10 시스템의 개발 방법, 구성 검증 결과를 제시한다. Korea Astronomy and Space Science Institute (KASI) has been operating (Satellite Ranging) system with repetition rate for satellite precise orbit spin determination as...
In this study, both the altitude error due to refraction and range delay in ionosphere with respect frequency are extracted according radar elevation analyze effect of atmosphere on space surveillance radar. To achieve this, radio refractivity profile is modeled using measured data from domestic weather stations. Then, altitude-error ray tracing method, frequency. Further, considerations for design characteristics discussed based abroad proposed This analysis expected be utilized...
Radar sensors are used for space situational awareness (SSA) to determine collision risk and detect re-entry of objects. The capability SSA radar system includes sensitivity such as the detectable cross-section a function range tracking indicate time measurement errors. duration target staying in cell is short; therefore, signal-to-noise ratio cannot be improved through pulse integration method pulse-Doppler signal processing. In this study, improving during migration presented. detection...
The correlation between meteorological data collected at the optical wide-field patrol network (OWL-Net) Station No. 1 and seeing of satellite observation was analyzed. Meteorological from June 2014 to November 2015 were analyzed outdoor air temperature, relative humidity, wind speed, cloud index data, full-width half-maximum (FWHM) data. annual pattern for Mongolia by collecting over four seasons, with collection beginning after installation initial set-up OWL-Net in Mongolia. A comparison...
Space debris poses significant threats to spacecraft and human activities in space. Accurate modeling of space is crucial for understanding mitigating these risks, ensuring the sustainability environment. This paper discusses importance environment, highlighting its critical role safeguarding assets orbit. Two primary methods modeling, namely 1D 3D approaches, are discussed detail, their respective strengths limitations elucidated. Furthermore, a comprehensive review existing models,...
The magnetite nanoparticles were synthesized using the sonochemical method with oleic acid as surfactant. average size of particles can be controlled by ratio R = [H2O]/[surfactant] in range 2 to 9 nm. prepared this shows narrow distribution. To prepare biopolymer(beta-glucan)-coated nanoparticles, beta-glucan solution was added magnetic colloid suspensions under ultrasonication at room temperature. coated colloidal various concentrations did not agglomerate for 15 days, indicating their...
Recently, the number of space objects around Earth has increased rapidly, necessitating systematic risk management. This paper proposes a dual-mode framework for assessing collision between objects. The proposed consists microscopic and macroscopic modes. former focuses on one-to-one events, latter assesses overall inside cell located in space. Two assessment case studies using two modes demonstrate effectiveness framework.
전기방사 방법으로 sulfonated poly(ether ether ketone) (SPEEK) 나노섬유를 제조하고, 압축성형법으로 고분자 전해질막 연료전지(polymer electrolyte membrane fuel cell, PEMFC)용 나노섬유막을 제조하였다. SPEEK의 최대 설폰화율은 95% 이었고 초기 열분해 온도는 약 <TEX>$280^{\circ}C$</TEX>로 PEEK 보다 낮았으며 접촉각은 설폰화도가 증가함에 따라 감소하였다. 나노섬유의 최적 인가전압, 유속, 방사거리(tip to collector distance, TCD) 및 농도는 각각 22 kV, 0.3 mL/hr, 5 cm, 23 wt% 평균 섬유직경은 47.6 nm 이었다. 한편, SPEEK 이온교환 나노섬유막의 함수율 이온교환용량은 설폰화 시간과 설폰화제 함량이 증가하였으며 최적값은 20%, 2.03 meq/g으로 Nafion 117 우수하였다. 막의 전기저항은 시간이 감소하였고 그 값은...
An optical tracking network, the Optical Wide-field patroL Network (OWL-Net), has been developed to maintain orbital ephemeris of 11 domestic low Earth orbit satellites. The schedule overlapped events were occurred in scheduling OWL-Net with reduction observation chances. A short-arc strategy for was tested reduce simulation and determination. In full-scale from January 2014 December 2016, most frequent 127, 132, 116 times 4th, 34th, 18th weeks 2014, 2015, respectively. average number event...
The Korean Institute of Technology Satellite (KITSAT-1) is the first satellite developed by Research Center and University Surrey. KITSAT-1 orbiting Earth’s orbit as space debris with a 1,320 km altitude after planned mission. Due to its relatively small size altitude, tracking was difficult task. In this research, we analyzed results for one year using Midland Space Radar (MSR) in Texas Poker Flat Incoherent Scatter (PFISR) Alaska operated LeoLabs, Inc. were on weekly basis MSR PFISR....