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Minimum Number of Observation Points for LEO Satellite Orbit Estimation by OWL Network
Maru Park,조중현,조성기,최진,Chun-Hwey Kim,박장현,임홍서,최영준,문홍규,배영호,Sun-youp Park,Ji-Hye Kim,Dong-Goo Roh,Hyun-Jung Jang,Young-Sik Park,정민지 한국우주과학회 2015 Journal of Astronomy and Space Sciences Vol.32 No.4
By using the Optical Wide-field Patrol (OWL) network developed by the Korea Astronomy and Space Science Institute (KASI) we generated the right ascension and declination angle data from optical observation of Low Earth Orbit (LEO) satellites. We performed an analysis to verify the optimum number of observations needed per arc for successful estimation of orbit. The currently functioning OWL observatories are located in Daejeon (South Korea), Songino (Mongolia), and Oukaïmeden (Morocco). The Daejeon Observatory is functioning as a test bed. In this study, the observed targets were Gravity Probe B, COSMOS 1455, COSMOS 1726, COSMOS 2428, SEASAT 1, ATV-5, and CryoSat-2 (all in LEO). These satellites were observed from the test bed and the Songino Observatory of the OWL network during 21 nights in 2014 and 2015. After we estimated the orbit from systematically selected sets of observation points (20, 50, 100, and 150) for each pass, we compared the difference between the orbit estimates for each case, and the Two Line Element set (TLE) from the Joint Space Operation Center (JSpOC). Then, we determined the average of the difference and selected the optimal observation points by comparing the average values.
Jang, Sujeong,Park, Seokho,Cho, Hyong-Ho,Yang, Ung,Kang, Maru,Park, Jong-Seong,Park, Sah-Hoon,Jeong, Han-Seong The Basic Science Institute Chosun University 2019 조선자연과학논문집 Vol.12 No.4
Mesenchymal stem cells (MSCs) are known to differentiate into multiple lineages, making neurogenic differentiation an important target in the clinical field. In the present study, we induced the neurogenic differentiation of cells using histone deacetylase (HDAC) inhibitors and studied their mechanisms for further differentiation in vitro. We treated cells with the HDAC inhibitors, MS-275 and NaB; and found that the cells had neuron-like features such as distinct bipolar or multipolar morphologies with branched processes. The mRNA expressions encoding for NEFL, MAP2, TUJ1, OLIG2, and SYT was significantly increased following HDAC inhibitors treatment compared to without HDAC inhibitors; high protein levels of MAP2 and Tuj1 were detected by immunofluorescence staining. We examined the mechanisms of differentiation and found that the Wnt signaling pathway and downstream mitogen-activate protein kinase were involved in neurogenic differentiation of MSCs. Importantly, Wnt4, Wnt5a/b, and Wnt11 protein levels were highly increased after treatment with NaB; signals were activated through the regulation of Dvl2 and Dvl3. Interestingly, NaB treatment increased the levels of JNK and upregulated JNK phosphorylation. After MS-275 treatment, Wnt protein levels were decreased and GSK-3β was phosphorylated. In this cell, HDAC inhibitors controlled the non-canonical Wnt expression by activating JNK phosphorylation and the canonical Wnt signaling by targeting GSK-3β.
최진,조중현,임홍서,최영준,Maru Park,Sun-youp Park,배영호,Dong-Goo Roh,조성기,Young-Sik Park,Hyun-Jung Jang,Ji-Hye Kim,박장현 한국우주과학회 2015 Journal of Astronomy and Space Sciences Vol.32 No.4
Several optical monitoring strategies by a ground-based telescope to protect a Geostationary Earth Orbit (GEO) satellite from collisions with close approaching objects were investigated. Geostationary Transfer Orbit (GTO) objects, Inclined GeoSynchronous Orbit (IGSO) objects, and drifted GEO objects forced by natural perturbations are hazardous to operational GEO satellites regarding issues related to close approaches. The status of these objects was analyzed on the basis of their orbital characteristics in Two-Line Element (TLE) data from the Joint Space Operation Center (JSpOC). We confirmed the conjunction probability with all catalogued objects for the domestic operational GEO satellite, Communication, Ocean and Meteorological Satellite (COMS) using the Conjunction Analysis Tools by Analytical Graphics, Inc (AGI). The longitudinal drift rates of GeoSynchronous Orbit (GSO) objects were calculated, with an analytic method and they were confirmed using the Systems Tool Kit by AGI. The required monitoring area was determined from the expected drift duration and inclination of the simulated target. The optical monitoring strategy for the target area was analyzed through the orbit determination accuracy. For this purpose, the close approach of Russian satellite Raduga 1-7 to Korean COMS in 2011 was selected.
Magnitude Standardization Procedure for OWL-Net Optical Observations of LEO Satellites
Dong-Goo Roh,최진,조중현,임홍서,Sun-youp Park,Maru Park,최영준,배영호,Young-Sik Park,Hyun-Jung Jang,조성기,Ji-Hye Kim,박장현 한국우주과학회 2015 Journal of Astronomy and Space Sciences Vol.32 No.4
As a governmentally approved domestic entity for Space Situational Awareness, Korea Astronomy and Space Science Institute (KASI) is developing and operating an optical telescopes system, Optical Wide-field PatroL (OWL) Network. During the test phase of this system, it is necessary to determine the range of brightness of the observable satellites. We have defined standard magnitude for Low Earth Orbit (LEO) satellites to calibrate their luminosity in terms of standard parameters such as distance, phase angle, and angular rate. In this work, we report the optical brightness range of five LEO Satellites using OWL-Net.
( Hoonsung Park ),( Maru Kim ),( Dae-sang Lee ),( Tae Hwa Hong ),( Doo-hun Kim ),( Hangjoo Cho ) 대한외상학회 2023 大韓外傷學會誌 Vol.36 No.4
Inferior vena cava (IVC) injuries, while accounting for fewer than 0.5% of blunt abdominal trauma cases, are among the most difficult to manage. Despite advancements in prehospital care, transportation, operative techniques, and perioperative management, the mortality rate for IVC injuries has remained at 20% to 66% for several decades. Furthermore, 30% to 50% of patients with IVC injuries succumb during the prehospital phase. A 65-year-old male patient, who had been struck in the back by a 500-kg excavator shovel at a construction site, was transported to a regional trauma center. Injuries to the right side of the infrarenal IVC and the right external iliac vein (EIV) were suspected, along with fractures to the right iliac bone and sacrum. The injury to the right side of the infrarenal IVC wall was repaired, and the right internal iliac artery was ligated. However, persistent bleeding around the right EIV was observed, and we were unable to achieve proximal and distal control of the right EIV. Attempts at prolonged manual compression were unsuccessful. To decrease venous return, we ligated the right superficial femoral vein. This reduced the amount of bleeding, enabling us to secure the surgical field. We ultimately controlled the bleeding, and approximately 5 L of blood products were infused intraoperatively. A second-look operation was performed 2 days later, by which time most of the bleeding sites had ceased. Orthopedic surgeons then took over the operation, performing closed reduction and external fixation. Five days later, the patient underwent definitive fixation and was transferred for rehabilitation on postoperative day 22.
[디젤엔진부문] 신경회로망을 이용한 HSDI Common-rail 인젝터의 모델링
윤마루(Maru Yoon),박승범(Seungbum Park),선우명호(Myoungho Sunwoo) 한국자동차공학회 2001 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2001 No.11_1
This study presents the process of the solenoid parameter estimation of an common-rail injector for HSDI(High Speed Direct Injection) diesel engines. The EMF(Electromotive Force) and solenoid inductance are the major parameters for presenting the injector dynamics, and also these parameters are estimated by using a multi-layer feedforward neural networks. The performance of parameter estimator is verified by the simulation with injector model. The feasibility of this methodology is closely examined through the simulation in the various operating points of injector. The simulation results have revealed that estimated parameters show favorable agreements with the common-rail injector model