• Journal of Astronomy and Space Sciences
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• 제35권4호
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• pp.227-233
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• 2018

This study presents the generation and accuracy assessment of predicted orbital ephemeris based on satellite laser ranging (SLR) for geostationary Earth orbit (GEO) satellites. Two GEO satellites are considered: GEO-Korea Multi-Purpose Satellite (KOMPSAT)-2B (GK-2B) for simulational validation and Compass-G1 for real-world quality assessment. SLR-based orbit determination (OD) is proactively performed to generate orbital ephemeris. The length and the gap of the predicted orbital ephemeris were set by considering the consolidated prediction format (CPF). The resultant predicted ephemeris of GK-2B is directly compared with a pre-specified true orbit to show 17.461 m and 23.978 m, in 3D root-mean-square (RMS) position error and maximum position error for one day, respectively. The predicted ephemeris of Compass-G1 is overlapped with the Global Navigation Satellite System (GNSS) final orbit from the GeoForschungsZentrum (GFZ) analysis center (AC) to yield 36.760 m in 3D RMS position differences. It is also compared with the CPF orbit from the International Laser Ranging Service (ILRS) to present 109.888 m in 3D RMS position differences. These results imply that SLR-based orbital ephemeris can be an alternative candidate for improving the accuracy of commonly used radar-based orbital ephemeris for GEO satellites.

• 천문학논총
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• 제30권2호
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• pp.593-594
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• 2015

We present our analysis results for an updated orbital ephemeris for the dipping low mass X-ray binary 4U 1624-49, using the light curve collected by the All Sky Monitor (ASM) on board the Rossi X-ray Timing Explorer (RXTE) and the Monitor of All-Sky X-ray Image (MAXI). To make clear dip profiles, the light curve from the ASM and the MAXI were divided into ten 500d segments and four 400d segments for ASM and MAXI light curves, respectively, and folded with the linear ephemeris proposed by Smale et al. (2001). The phases of dip centers were determined by the method adopted from Hu et al. (2008). The phase drift was then fitted with a linear function. We obtained an updated orbital period of 0.869896(1) d and a phase zero epoch of JD 2450088.6618(57). No clear orbital period derivative is detected with a 2-sigma upper limit of $1.4{\times}10^{-6}(yr)^{-1}$ from a quadratic curve fitting of the dip phase evolution.

• 한국정밀공학회지
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• 제27권4호
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• pp.27-32
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• 2010

This paper presents an investigation into the pinhead forming process with the objective of finding the optimal forming conditions. In order to this, the orbital forming analysis of a heading MIG was carried out using the explicit finite element method. Relationships between temperature by forming of load and stresses, rake angle by forming final shape and stress distribution were investigated through analysises in order to find an efficient solution. As a result, the higher temperature and orbital rake angle were the better forming conditions.

• Bulletin of the Korean Chemical Society
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• 제22권5호
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• pp.499-502
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• 2001

Unexpectedly, the brightest row was known to represents the lowest lying Te atoms in the STM image of NbTe2. Projected density of states and crystal orbital overlap population show that the 5pz orbital of the lowest lying Te(2) atom doe s not interact with the 4d orbital of Nb strongly so that the 5pz band remains in the vicinity of the Fermi energy. Consequently the lowest lying Te(2) atoms contribute higher electron density near the Fermi energy which in turn exhibits brightest image in the STM experiments.

• Bulletin of the Korean Chemical Society
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• 제18권9호
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• pp.976-981
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• 1997

The magnetic susceptibilities of molybdenum ions with 4d1 electronic configuration in the octahedral crystal field were calculated on the basis of ligand field theory. The experimental magnetic susceptibilities for molybdenum ions, which are stabilized at the octahedral site in the perovskite lattice of Ba2ScMoⅤO6 and Sr2YMoⅤO6, were compared with the theoretical ones. We have tried to fit their temperature dependence of magnetic susceptibility with ligand field parameters, spin-orbit coupling constant ζSO, and orbital reduction parameter κ according to intermediate field coupling and strong field theory. Strong field coupling theory could not explain experimental curves without unrealistically large axial ligand field, since it ignores the mixing up between different state via spin-orbit interaction and ligand field. On the other hand, the intermediate field coupling theory could successfully reproduce experimental data in octahedral and trigonal ligand field. The fitting result demonstrates not only the fact that spin-orbit interaction is primarily responsible for the variation of magnetic behavior but also the fact that effective orbital overlap, enhanced by cubic crystal structure, reduces significantly orbital angular momentum as indicated by κ parameter.

• 천문학회지
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• 제46권4호
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• pp.151-159
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• 2013

We discuss the orbital period changes of the Algol semi-detached eclipsing binary DI Peg by constructing the (O-C) residual diagram via using all the available precise minima times. We conclude that the period variation can be explained by a sine-like variation due to the presence of a third body orbiting the binary, together with a long-term orbital period increase (dP/dt=0.17 sec/century) that can be interpreted to be due to mass transfer from the evolved secondary component (of rate $1.52{\times}10^{-8}M_{\odot}/yr$) to the primary one. The detected low-mass third body ($M_{3min.}=0.22{\pm}0.0006M_{\odot}$) is responsible for a periodic variation of about 55 years light time effect. We have determined the orbital parameters of the third component which show a considerable eccentricity $e_3=0.77{\pm}0.07$ together with a longitude of periastron ${\omega}_3=300^{\circ}{\pm}10^{\circ}$.

• 대한화학회지
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• 제57권4호
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• pp.461-471
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• 2013

Optimized geometrical structure, atomic charges, molecular electrostatic potential, nonlinear optical (NLO) effects and thermodynamic properties of the title compound N-(2,5-methylphenyl)salicylaldimine (I) have been investigated by using ab initio quantum chemical computational studies. Calculated results showed that the enol form of (I) is more stable than keto form. The solvent effect was investigated for obtained molecular energies, hardneses and the atomic charge distributions of (I). Natural bond orbital and frontier molecular orbital analysis of the title compound were also performed. The total molecular dipole moment (${\mu}$), linear polarizability (${\alpha}$), and first-order hyperpolarizability (${\beta}$) were calculated by B3LYP method with 6-31G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d) and 6-311++G(d,p) basis sets to investigate the NLO properties of the compound (I). The standard thermodynamic functions were obtained for the title compound with the temperature ranging from 200 to 450 K.

• 대한두개안면성형외과학회지
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• 제25권4호
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• pp.161-170
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• 2024

Background: The eyes are the central aesthetic unit of the face. Maxillofacial trauma can alter facial proportions and affect visual function with varying degrees of severity. Conventional approaches to reconstruction have numerous limitations, making the process challenging. The primary objective of this study was to evaluate the application of three-dimensional (3D) navigation in complex unilateral orbital reconstruction. Methods: A prospective cohort study was conducted over 19 months (January 2020 to July 2021), with consecutive enrollment of 12 patients who met the inclusion criteria. Each patient was followed for a minimum period of 6 months. The principal investigator carried out a comparative analysis of several factors, including fracture morphology, orbital volume, globe projection, diplopia, facial morphic changes, lid retraction, and infraorbital nerve hypoesthesia. Results: Nine patients had impure orbital fractures, while the remainder had pure fractures. The median orbital volume on the normal side (30.12 cm³; interquartile range [IQR], 28.45-30.64) was comparable to that of the reconstructed orbit (29.67 cm³; IQR, 27.92-31.52). Diplopia improved significantly (T(10)= 2.667, p= 0.02), although there was no statistically significant improvement in globe projection. Gross symmetry of facial landmarks was achieved, with comparable facial width-to-height ratio and palpebral fissure lengths. Two patients reported infraorbital hypoesthesia at presentation, which persisted at the 6-month follow-up. Additionally, five patients developed lower lid retraction (1-2 mm), and one experienced implant impingement at the infraorbital border. Conclusion: Our study provides level II evidence supporting the use of 3D navigation to improve surgical outcomes in complex orbital reconstruction.

• 대한화학회지
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• 제41권6호
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• pp.277-283
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• 1997

질소를 포함한 평면형리간드가 배위된 백금(II)착물([$Pt(L)_2X_2$]; L=isoxazole(isox), 3,5-dimethylisoxazole(3,5-diMeisox), 3-methyl,5-phenylisoxazole(3-Me,5-Phisox), and 4-amino-3,5-dimethylisoxazole(4-ADI); X=Cl, Br)의 항암활성을 분자역학(MM2)법으로 최소에너지를 갖는 구조를 구한 후 확장분자궤도함수(Extended Huckel Molecular Orbital)법으로 조사하였다. X 원자의 알짜전하 값은 cis-, trans-이성체 모두 평면리간드의 N 원자보다 음의 값으로 크게 나타나서, N 원자보다 X 원자의 이탈이 용이함을 알 수가 있었고, ${\sigma}MO$에너지 준위로 비교한 결과도 $Pt(d_{x2-y2})-X(P_x)$의 ${\sigma}MO$에너지 준위$(E{\sigma}_{(Pt-X)})$가 $Pt(d_{x2-y2})-N(P_x)$의 ${\sigma}MO$에너지 준위$(E{\sigma}_{(Pt-N)})$보다 예외없이 높아서 Pt-N보다 Pt-X의 결합이 약함을 알 수 있었다. 또한 X 원자의 cis-, trans-이성체에서의 이탈 용이성을 비교하기 위하여 중심금속과 리간드사이의 ${\sigma}MO$에너지준위로 비교한 결과, trans-이성체에서 $Pt(d_{x2-y2})-N(P_x)$의 ${\sigma}MO$에너지준위$(E{\sigma}_{(Pt-X)})$가 cis-이성체에서 보다 예외없이 높아서 결합이 약함을 알 수 있었다. 아울러 같은 착물에서 cis-보다 trans-착물에서 Pt-X의 결합이 약함을 알 수 있었다, 따라서 $X^-$이온으로 떨어져 나가는 용이성과 그 구조변화가 항암활성과 관계가 있을 것으로 생각하였다. 즉, $E{\sigma}_{(P-N)}-E{\sigma}_{(P1-X)}$가 클수록 저해활성 계수 logIA값이 크게 나타나서 실험적 사실과 일치함을 알 수 있었다.

• 대한두개안면성형외과학회지
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• 제25권1호
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• pp.27-30
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• 2024

Fungal sinusitis is relatively rare, but it has become more common in recent years. When fungal sinusitis invades the orbit, it can cause proptosis, chemosis, ophthalmoplegia, retroorbital pain, and vision impairment. We present a case of an extensive orbital floor defect due to invasive fungal sinusitis. A 62-year-old man with hypertension and a history of lung adenocarcinoma, presented with right-side facial pain and swelling. On admission, the serum glucose level was 347 mg/dL, and hemoglobin A1c was 11.4%. A computed tomography scan and a Waters' view X-ray showed right maxillary sinusitis with an orbital floor defect. On hospital day 3, functional endoscopic sinus surgery was performed by the otorhinolaryngology team, and an aspergilloma in necrotic inflammatory exudate obtained during exploration. On hospital day 7, orbital floor reconstruction with a Medpor Titan surgical implant was done. In principle, the management of invasive sino-orbital fungal infection often begins with surgical debridement and local irrigation with an antifungal agent. Exceptionally, in this case, debridement and immediate orbital floor reconstruction were performed to prevent enophthalmos caused by the extensive orbital floor defect. The patient underwent orbital floor reconstruction and received intravenous and oral voriconazole. Despite orbital invasion, there were no ophthalmic symptoms or sequelae.