• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.147-150
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• 1998

To determine the satellite orbital positions under consideration of interference caused by inter-satellite systems is one of the most important issues in terms of optimal usage of satellite network resources. In this paper, we present the orbital positioning method for a new satellite to minimize inter-satellite system interference effect in the fixed satellite communication using a new method. Through the computer simulation, it is clear that the proposed method is suitable to determine the satellite orbital positions.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.501-504
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• 2005

In general, most incomplete communication link setup between satellite and ground station right after separation from launcher come from less accurate orbital vector ground station uses to track the satellite because only predicted orbital state vector is available during first few orbits. This paper describes the developed procedure for successful initial acquisition for KOMPSAT-2 using scanning functions ofK13 antenna system with predicted orbital information. Azimuth scan, raster scan, spiral scan functions were tested with KOMPSA Tl under intentionally degraded orbital information for antenna operation. Through tests, spiral scan function was decided to be best search scan among 3 scans. Developed procedure can assure the successful acquisition only if azimuth offset and time offset value are within +/-2deg and +/-30sec, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2763-2771
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• 1997

To determine the satellite orbital positions considering interference caused by inter-satellite systems is one of the most improtant issues in terms of optimal usage of satellite network resources. In this paper, considering ITU filing situation, we present the satellite orbital positions determination method to minimize iter-satellite system interference effect in the fixed satellite communication using an optimization method. Through the computer simulatio, it was shown that the proposed method is suitable to determine the satellite orbital positions.

• Archives of Craniofacial Surgery
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• v.16 no.2
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• pp.67-72
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• 2015

Background: A schwannoma is a benign, slow-growing peripheral nerve sheath tumor that originates from Schwann cells. Orbital schwannomas are rare, accounting for only 1% of all orbital neoplasms. In this study, we retrospectively review orbital schwannomas and characterize clinical, radiologic, and histologic features of this rare entity. Methods: A retrospective review was performed to identify patients with histologically confirmed orbital schwannoma, among a list of 437 patients who had visited our hospital with soft tissue masses within the orbit as the primary presentation between 2010 and 2014. Patient charts and medical records were reviewed for demographic information, relevant medical and family history, physical examination findings relating to ocular and extraocular sensorimotor function, operative details, postoperative complications, pathologic report, and recurrence. Results: Five patients (5/437, 1.1%) were identified as having histologically confirmed orbital schwannoma and underwent complete excision. Both computed tomography (CT) and magnetic resonance imaging (MRI) studies were not consistent in predicting histologic diagnosis. There were no complications, and none of the patients experienced significant scar formation. In two cases, patients exhibited a mild postoperative numbness of the forehead, but the patients demonstrated full recovery of sensation within 3 months after the operation. None of the five patients have experienced recurrence. Conclusion: Orbital schwannomas are relatively rare tumors. Preoperative diagnosis is difficult because of its variable presentation and location. Appropriate early assessment of orbital tumors by CT or MRI and prompt management is warranted to prevent the development of severe complications. Therefore, orbital schwannomas should be considered in the differential diagnosis of slow-growing orbital masses.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.11
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• pp.989-996
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• 2012

The purpose of this paper is to analyze GPS (Global Positioning System) satellite orbital mechanics, and then to propose a novel long-term GPS satellite orbit prediction scheme including virtual planet perturbation. The GPS orbital information is a necessary prerequisite to pinpointing the location of a GPS receiver. When a GPS receiver has been shut down for a long time, however, the time needed to fix it before its reuse is too long due to the long-standing GPS orbital information. To overcome this problem, the GPS orbital mechanics was studied, such as Newton's equation of motion for the GPS satellite, including the non-spherical Earth effect, the luni-solar attraction, and residual perturbations. The residual perturbations are modeled as a virtual planet using the least-square algorithm for a moment. Through the modeling of the virtual planet with the aforementioned orbital mechanics, a novel GPS orbit prediction scheme is proposed. The numerical results showed that the prediction error was dramatically reduced after the inclusion of virtual planet perturbation.

• Bulletin of the Korean Chemical Society
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• v.19 no.5
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• pp.527-530
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• 1998

This paper presents the electrochemistry and molecular orbital (MO) picture of a series of conformationally-restricted thioxantone derivatives. A series of $C_2-substituted$ thioxanthones were examined to probe the electronic influence of the substituent on the electrooxidation and electroreduction sites (i.e., on the electron densities at the 10-and 9-positions), respectively. In the presence of "electrophoric" groups such as C=O and S, characteristic electrochemical reduction and oxidation responses are observed. The electrochemical reaction was diffusion-controlled, because the $I_p/{\upsilon}^{1/2}$ ratio was constant for the anodic and cathodic wave of thioxantone derivatives. These substituent effects are presented in terms of correlations of oxidation (or reduction) potentials with the highest occupied molecular orbital (HOMO), or lowest unoccupied molecular orbital (LUMO) energies, respectively. There is good correlation between energies of the HOMO vs. $E_{pa}^{(+)}$ and energies of the LUMO vs. $E_{pc}^{(-)}$. Frontier Molecular Orbital (FMO) is changed by the functional group of thioxanthones. FMO energy level was offered us the information about the electron transfer direction, and the coefficient of FMO was offered the information about the electron transfer position. Sulfur atom has an important effect on oxidation potential, $E_{pa}^{(+)}$ and the carbonyl carbon has an important effect on reduction potential, $E_{pc}^{(-)}$. Therefore we were appreciated that the contribution of sulfur atom for the $E_{pa}^{(+)}$ and HOMO energies is larger than the contribution of carbonyl group for the $E_{pc}^{(-)}$ and LUMO energies.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.4
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• pp.292-300
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• 2004

Orbital blowout fractures are common consequence to blunt periorbital trauma. Pure orbital blowout fractures first occur at the weakest point of the orbital wall. Computed tomography(CT) is recognized to be the best imaging technique to evaluate orbital fractures. The extent and location of a blowout fractures in the CT scan were noted to have an effect on the clinical outcome. In the early posttraumatic period, the presence of significant enophthalmos is difficult to detect because of orbital edema. Early surgical intervention may improve the ultimate outcome because open reconstruction becomes more difficult if surgery is delayed. In this study, we evaluated isolated blowout fractures of the orbital floor by region-of-interest measurements from CT scans and their relationship to ophthalmologic findings. Six patients of the medial orbital wall fractures, eleven patients of the inferior orbital wall fractures, nineteen of the medial and the inferior orbital wall fractures confirmed by CT scan, were evaluated. The area of fracture and the volume of the displaced orbital tissue were determined from CT scan using linear measurements. Each of the calculated values for the area and the volume were compared with the degree of the enophthalmos, the diplopia, and the eyeball movement limitation to determine whether there was any significant relationship between them. The fracture area and the volume of the herniated orbital tissue were significantly positively correlated with the enophthalmos and the ocular motility limitation and not correlated with the diplopia. For the enophthalmos of 2mm or greater, the mean fracture area was 3.55{\pm}1.25cm^2$ and the volume of the herniated orbital tissue was $1.74{\pm}0.97cm^3$; for less than 2mm enophthalmos, $1.43{\pm}0.99cm^3$ and $0.52{\pm}0.49cm^3$, respectively. The enophthalmos of 2mm can be expected with $2.92cm^2$ of the fracture area and $1.40cm^3$ of the herniated orbital tissue. In conclusion, the enophthalmos of 2mm or more, which is a frequent indication for surgery. It can be expected when area of fracture is $2.92cm^2$ or more, or the volume of herniated orbital tissue is $1.40cm^3$ or more. And the CT scan using linear measurements has an application in the assessment of patients with blowout fractures and provides useful information in the posttraumatic evaluation of orbital fractures.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.128-131
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• 2017

We explore the inverse electron demand Diels-Alder reactions of tetrazines with various functional groups employing quantum calculations. In general, the rate of inverse electron demand Diels-Alder reaction depends on molecular orbital levels of electron donor and electron acceptor. Likewise, ${\pi}$ orbital of the dienophile and ${\pi}^*$ orbital of the diene is a key factor. In this work, we discuss the case where the energy of diene's ${\pi}^*$ molecular orbital is not the sole governing factor to determine the reaction rate, rather the rate shows strong correlation with the charge density of dienes.

• Journal of information and communication convergence engineering
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• v.20 no.1
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• pp.41-48
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• 2022

With the development of technology, the procedures for making systems are altered. Jobs that were initially difficult with technology have become easier. Likewise with work as a developer. In this era, it takes work that can be done quickly, precisely, and accurately. Inspired by the Copernicus' theory that the sun is the center of the solar system, this research aims to create a plugin that is integrated with the Unity game engine so that it can create dungeons quickly and dynamically using the orbital dungeon generation method. In general, games that have several dungeons are role playing games genre with the roguelike subgenre, where games of this type are widely adopted by well-known games. This method is expected to be employed by developers, especially game developers, to simplify and speed up the creation of games using dungeons, because the complexity of the system that is made can be adjusted according to needs.

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.21-21
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• 2006