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이지만(Ji Marn Lee),노태수(Tae Soo No),정옥철(Ok-Chul Jung),정대원(Dae-Won Chung) 한국항공우주학회 2012 韓國航空宇宙學會誌 Vol.40 No.9
본 논문에서는 태양동기성 유지 및 지상궤적 반복이 요구되는 위성의 궤도 설계 방법에 대한 연구를 수행하였다. 특히, 위성 궤도 해석 및 공학 문제에서 빈번하게 사용되는 상용 소프트웨어 (STK, MATLAB)를 활용한 “비선형 시뮬레이션 기반 수치 최적화” 기법을 제안하고자 한다. 설계 과정에서 위성에 미치는 다양한 교란력을 고려함으로써, 태양 동기성과 지상궤적 반복과 같은 임무 요구 사항을 더 정확하게 만족할 뿐만 아니라, 위성 지방시 변화 최소화, 특정 지상국과 접촉 시간 최대화와 같이 실제 위성 운용시 현실적으로 요구되는 사항을 설계에 반영할 수 있다. 저궤도 태양동기궤도 위성을 대상으로 설계 예제를 제시하였고, 본 연구의 타당성을 검증하였다. This paper presents a mission orbit design method for spacecraft which use the sun-synchronous and ground repeat orbits. In this work, we have proposed a new design procedure, “Nonlinear simulation-based numerical optimization technique” using the commercial S/W’s such as STK (Satellite Tool kit) and Matlab, which are widely adopted S/W’s in the area of orbital mechanics and engineering analysis. Inclusion of all the perturbation effects on the spacecraft not only can more precisely satisfy the mission requirements for sun-synchronicity and repeated ground track, and also operational requirements such as minimum change in the S/C local time, maximization of the contact time with a specified ground station, etc. can be appropriately considered. Design examples for LEO sun-synchronous mission are presented to demonstrate the usefulness of the proposed method in this paper.
Reports : Effects of different target sites on antisense RNA-mediated regulation of gene expression
( Hong Marn Park ),( Yeong Seong Yoon ),( Shi Nae Suk ),( Ji Young Lee ),( Young Hoon Lee ) 생화학분자생물학회(구 한국생화학분자생물학회) 2014 BMB Reports Vol.47 No.11
Antisense RNA is a type of noncoding RNA (ncRNA) that binds to complementary mRNA sequences and induces gene repression by inhibiting translation or degrading mRNA. Recently, several small ncRNAs (sRNAs) have been identified in Escherichia coli that act as antisense RNA mainly via base pairing with mRNA. The base pairing predominantly leads to gene repression, and in some cases, gene activation. In the current study, we examined how the location of target sites affects sRNA-mediated gene regulation. An efficient antisense RNA expression system was developed, and the effects of antisense RNAs on various target sites in a model mRNA were examined. The target sites of antisense RNAs suppressing gene expression were identified, not only in the translation initiation region (TIR) of mRNA, but also at the junction between the coding region and 3`` untranslated region. Surprisingly, an antisense RNA recognizing the upstream region of TIR enhanced gene expression through increasing mRNA stability. [BMB Reports 2014; 47(11): 619-624]
Park Marn Joon,Kim Yoon-Ji,정유삼 대한수면학회 2022 sleep medicine research Vol.13 No.2
Due to glossal and craniofacial skeletal abnormalities, children with Down syndrome (DS) are prone to obstructive sleep apnea (OSA), thus demanding an increased necessity for an earlier diagnosis and more strict control for OSA. Adenotonsillectomy (T&A op) is an effective surgical treatment method to reduce OSA in children. Nevertheless, it should be noted that T&A op in DS children might be insufficient to completely resolve OSA and that extra care is needed when performing a T&A op for airway obstruction in DS during the immediate postoperative period. The objective of the present study was to report a case of a 2-year-old male DS patient with severe OSA (apnea-hypopnea index [AHI] of 61.7/hr) which was consequently reduced to moderate OSA (AHI of 7.6/hr), followed by reduction to mild OSA (AHI of 4.8/hr) with an one-year of rapid maxillary expansion (RME) device application. With a 2-year application of the RME device, the hard palate width in the 1st and 2nd molar region was increased to 5.86 mm and 5.26 mm, respectively. This is the first case report describing that a severe OSA is reduced to moderate OSA with T&A op and further reduced to mild OSA with an RME device application.
A Study on Earth-Moon Transfer Orbit Design
No, Tae-Soo,Lee, Ji-Marn,Jeon, Gyeong-Eon,Lee, Dae-Ro,Kim, Ghang-Ho The Korean Society for Aeronautical and Space Scie 2012 International Journal of Aeronautical and Space Sc Vol.13 No.1
Optimal transfer trajectories based on the planar circular restricted three body problem are designed by using mixed impulsive and continuous thrust. Continuous and dynamic trajectory optimization is reformulated in the form of discrete optimization problem. This is done by the method of direct transcription and collocation. It is then solved by using nonlinear programming software. Two very different transfer trajectories can be obtained by the different combinations of the design parameters. Furthermore, it was found out that all designed trajectories permit a ballistic capture by the Moon's gravity. Finally, the required thrust profiles are presented and they are analyzed in detail.
A Study on Earth-Moon Transfer Orbit Design
Tae Soo No,Ji Marn Lee,Gyeong Eon Jeon,Daero Lee,Ghangho Kim 한국항공우주학회 2012 International Journal of Aeronautical and Space Sc Vol.13 No.1
Optimal transfer trajectories based on the planar circular restricted three body problem are designed by using mixed impulsive and continuous thrust. Continuous and dynamic trajectory optimization is reformulated in the form of discrete optimization problem. This is done by the method of direct transcription and collocation. It is then solved by using nonlinear programming software. Two very different transfer trajectories can be obtained by the different combinations of the design parameters. Furthermore, it was found out that all designed trajectories permit a ballistic capture by the Moon’s gravity. Finally, the required thrust profiles are presented and they are analyzed in detail.
임정흠(Im, Jeong-Heum),이지만(Lee, Ji Marn),김성훈(Kim, Sung Hoon) 한국항공우주연구원 2017 항공우주산업기술동향 Vol.15 No.2
항공우주연구원은 공공분야의 위성영상 수요에 효과적으로 대응하고 국내 위성산업의 저변확대를 위해 차세대중형위성 1호를 개발하고 있다. 차세대중형위성 2호는 1호와 동일한 설계 규격으로 개발되어 1호와 군집위성 개념으로 운용될 예정이다. 이러한 군집위성 설계 및 운용은 미국, 프랑스, 이탈리아, 독일 등 위성 선진국에 의해 기 운용되고 있다. 본 논문에서는 해외 군집위성 운용사례를 조사하였으며 군집위성 개념을 고려한 차세대중형위성 2호기 궤도 설계 및 해석을 수행하였다. KARI is developing the CAS(Compact Advanced Satellite)500-1 satellite system to satisfy the satellite image demands in the public sector and to expand the basis of the domestic satellite industry. CAS500-2 will be developed with the same technical specifications as the CAS500-1 and it will be operated with the CASE500-1 in the concept of constellation. Constellation design and operation have been materialized by satellite advanced countries such as USA, France, Italy, UK and Germany. In this paper, overseas constellation design cases were investigated. And the CAS500-2 orbit was designed and analyzed considering the constellation concept.
혼합 추력 방식의 지구-달 최적 전이궤적 설계인자에 따른 비교연구
이대로(Daero Lee),노태수(Tae Soo No),이지만(Ji Marn Lee),전경언(Gyeong Eon Jeon) 한국항공우주학회 2011 韓國航空宇宙學會誌 Vol.39 No.11
본 논문은 혼합 추력 방식의 지구-달 최적 전이궤적의 설계를 위하여 설계인자에 따른 비교연구를 수행하였다. 지구 및 달의 인력을 동시에 고려하는 평면상 원형 제한 3체 궤도 운동 모델을 바탕으로 지구 출발시에는 순간 추력을, 지구-달 천이 과정 및 달 임무궤도 투입시에는 연속 추력을 사용하는 혼합형 궤적전이 방법을 적용하였다. 설계 인자로 설정된 추력 가중치와 비행시간의 다양한 조합에 따라 지구 출발시 Direct Departure 및 Spiral Departure Trajectory, 달 도착시 무추력 투입(Ballistic Capture)이 가능한 전이궤적를 설계하였고, 각 궤적에 필요한 순간 및 연속 추력 요구량을 상세히 제시하였다. This paper presents the results of a parametric study for the design of optimal Earth-Moon transfer trajectory using mixed impulsive and continuous thrust. Various types of the optimal Earth-Moon transfer trajectories were designed by adjusting the relative weight between the impulsive and the continuous thrust, and flight time. Two very different transfer trajectories can be obtained by different combination of design parameters. Furthermore, it was found that all thus designed trajectories permit the ballistic capture by the Moon gravity. Finally, the required thrust profiles are presented and analyzed in detail.