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아리랑위성 2호, 5호의 우주파편 충돌회피기동 주기 분석
김은혁(Eun-Hyouek Kim),김해동(Hae-Dong Kim),김은규(Eun-Kyou Kim),김학정(Hak-Jung Kim) 한국항공우주학회 2011 韓國航空宇宙學會誌 Vol.39 No.11
본 논문에서는 현재 운용 중인 아리랑위성 2호와 발사예정인 아리랑위성 5호의 우주파편 충돌 회피기동 주기를 분석하였다. 이때, 각 위성들의 임무궤도 특성, 충돌 회피 여유시간, 허용 충돌확률, 위치 불확실성 등의 인자들의 변화에 따라 분석을 수행하였다. 또한, 결과의 타당성을 검증하기 위해 실제 1년 동안 생성된 NORAD TLE 카탈로그(catalog) 상의 우주 물체들과 아리랑위성 2호와의 충돌 회피기동 주기를 계산하였다. 분석 결과, 두 위성 모두 연중 약 1회 충돌 회피기동이 요구됨을 확인할 수 있었으며, 계산 인자들의 변화에 따른 결과 분석을 통해 추후 발사 예정인 저궤도 위성들의 충돌 회피기동 주기 예측 정밀도를 향상시키기 위한 방안들을 제시하였다. In this paper, a collision avoidance maneuver frequency for the KOMPSAT-2 and the KOMPSAT-5 is analyzed. For the statistical prediction of the avoidance maneuver frequency, mission orbits, responsive time, accepted collision probabilities, and positional uncertainties of primary and secondary objects are considered. In addition, the collision avoidance maneuver frequency of the KOMPSAT-2 is compared to the case that NORAD catalog during one year is used to calculate that of the KOMPSAT-2. As a result, the collision avoidance maneuver frequency is one per year on average and effective factors on the statistical prediction of the avoidance maneuver frequency are investigated. Efforts to improve its prediction accuracy are also discussed.
Synthesis and Crystal Structure of Yttria-Stabilized Zirconia
김원사,서일환,박로학,김문집,김헌준,이창희,김용채,성백석,이정수,심해섭,김이경,이진호,Kim, Won-Sa,Suh, Il-Hwan,Bak, Ro-Hak,Kim, Moon-Jib,Kim, Huhn-Jun,Lee, Chang-Hee,Kim, Yong-Che,Seong, Baek-Seok,Lee, Jeong-Soo,Shim, Hae-Seop,Kim, Yi-Kyu 한국지구과학회 1997 韓國地球科學會誌 Vol.18 No.6
등축정계의 결정구조를 지니는 무색 투명한 저코니아($Zr_{0.73}Y_{0.27}O_{1.87}$) 결정을 $Y_2O_3$를 안정제로 사용하여 Bridgman-Stockbager법(또는 Skull 용융법)으로 합성하였다. 육성된 결정은 유리광택을 나타내며 동시에 약간의 지방 광택도 띤다. 저코니아 결정은 편광현미경하에서 등방성을 나타내며 이방성의 징후는 발견되지 않는다. 모스 경도는 $8{\sim}8\frac{1}{2}$이고 비중은 5.85이다. 자외선하에서는 약한 백색 형광을 낸다. 단결정법으로 결정한 저코니아의 결정구조는 등축정계이며, 공간군은 $Fm3m({O^5}_h)$이다. 단위포 상수(a)는 $5.1552(5){\AA}$이며, $V=136.99(5){\AA}$, Z=4, R=0.0488이다. 저코니움 원자는 각 모서리에 산소 원자가 자리잡고 있는 육면체의 중심에 위치하고 있으며, 각 산소 원자는 저코니움 원자로 되어 있는 사면체의 중심에 위치하고 있다. 결국 8:4의 배위수가 성립하는 구조를 하고 있다. Colorless and transparent cubic zirconia($Zr_{0.73}Y_{0.27}O_{1.87}$) crystal has been synthesized by the Bridgman-Stock-bager method(also called Skull melting method). $Y_2O_3$ is used as stabilizer. The crystal shows a vitreous luster with a slight oily appearance. Under a polarizing microscope, it shows isotropic nature with no appreciable anisotropism. Mohs hardness value is measured to be $8{\sim}8\frac{1}{2}$ and specific gravity 5.85. Under ultraviolet light it shows a faint white glow. The crystal structure of yttria stabilized zirconia was determined, using single crystal X-ray diffraction techniques to be a cubic symmetry, space group $Fm\overline{3}m({O^5}_h)$ with $a=5.1552(5){\AA}$, $V=136.99(5){\AA}^3$, Z=4, and R=0.0488 for 29 unique reflections. Each zirconium atom is at the center of eight oxygen atoms situated at the corners of a surrounding cube and each oxygen atom is at the center of a tetrahedron of zirconium atoms. So a coordination of 8:4 holds in the structure.
한선희,김봉환,김학준,박준성,박혜빈,김미정,박주형,김진솔,이경훈,김종환,하나리,Han, Sun-Hee,Kim, Bong-Hwan,Kim, Hak-Jun,Park, Jun-Sung,Park, Hae-Been,Kim, Mi-Jeong,Park, Ju-Hyeong,Kim, Jin-Sol,Lee, Kyeong-Hoon,Kim, Jong-Hwan,Ha, Na-Ri 한국임상보건과학회 2015 한국임상보건과학회지 Vol.3 No.4
Purpose. This study was to investigate comparison of the near eye position according to the spectacle and contact lens wearing. Methods. We measured the AC/A ratio and near horizontal phoria using modified Thorington method in each case spectacle and contact lens wearing of equivalent spherical power after measuring the full corrected diopter for 20 subjects (men 5, woman 15, $21.15{\pm}1.35$ years) without specific ocular diseases, ocular surgery experience and vision anomalies. Results. It was shown high correlation between spectacle and contact lens wearing as AC/A ratio is a correlation coefficient 0.99 (p=0.00), near horizontal phoria is a correlation coefficient 0.95 (p=0.00). And contact lens wearing increased as AC/A ratio by $0.32{\pm}1.35$ ${\Delta}/D$ (p=0.31) and near horizontal phoria by $-0.17{\pm}2.18$ ${\Delta}$ (p=0.73) than spectacle wearing but there was no statistically significant difference. As the higher myopic grade AC/A ratio increased and then was shown decreased tendency in -6.00 D < $SED{\leq}-4.00$ D group (p>0.05) and as the higher myopic grade near exophoria increased but there was no statistically significant difference (p>0.05). Conclusions. We should consider that the subjects who had the lower AC/A ratio or higher near exophoria in -6.00 D < $SED{\leq}-4.00$ D group were necessary to measure AC/A ratio and near horizontal phoria when they were wearing contact lens because contact lens wearing tended to increase the near exophoria than spectacle wearing.
소환시 발생되는 아황산 가스가 흰쥐 혈청 중의 효소 활성도 및 지질 함량에 미치는 영향
김해동,김병학,하헌,조수열,윤수홍,Kim, Hae-Dong,Kim, Byung-Hak,Ha, Hun,Cho, Soo-Yeul,Yoon, Soo-Hong 환경독성보건학회 1997 환경독성보건학회지 Vol.12 No.3
Recently, incidences of pulmonary-related diseases are increasing and natural ecosystem is destroyed year by year owing to air pollutions by industrial noxious gases such as sulfur dioxide and carbon dioxide, etc. Sulfur dioxide produced by oxidation of sulfur compounds is water soluble and causes several kinds of pulmonary diseases, damaging on plants and animals. This study was undertaken to investigate effects of acute exposure of rats to sulfur dioxide using biochemical parameters. The sAST (aspartate transaminase) activity was not significantly affected but sALT (alanine transaminase), sLDH (lactate dehydrogenase) and sALP (alkaline phosphatase) activities were significantly increased by acute sulfur dioxide gas exposure. Also sulfur dioxide gas treatment significantly diminished serum cholinesterase activity. The total lipid, triglyceride, total-, HDL- and LDL-cholesterol contents were significantly increased by sulfur dioxide gas exposures. But the body and liver weight were generally diminished in comparison with control group. Our results' showed increased enzyme activities and lipid contents, but body and liver weight were all diminished by sulfur dioxide gas treatment.
김혜미,김학령,Hak Seung Lee,정지현,Chee Hae Kim,Sooyeon Oh,Jung Ho Kim,조주희 대한심장학회 2014 Korean Circulation Journal Vol.44 No.3
Ante mortem cases of venous thrombosis in patients with nonbacterial thrombotic endocarditis (NBTE) have not yet been reported. We describea rare case of NBTE in a patient with mesenteric vein thrombosis. A healthy 37-year-old man with abdominal pain and fever underwentemergency small bowel resection due to bowel ischemia resulting from mesenteric vein thrombosis. Transthoracic echocardiographyrevealed multiple mobile masses attached to the anterior leaflet of the mitral valves and their chordae tendineae. On suspicion of infectiveendocarditis, the cardiac masses were excised through open-heart surgery. However, pathologic reviews were compatible with NBTE. Thepatient was stable after the cardiac surgery and was treated with warfarin. Laboratory and imaging findings regarding his hypercoagulablecondition were all negative.