• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.247-256
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• 2015

In this work, an efficient method with which to evaluate the high-degree-and-order gravitational harmonics of the non-sphericity of a central body is described and applied to state predictions of a lunar orbiter. Unlike the work of Song et al. (2010), which used a conventional computation method to process gravitational harmonic coefficients, the current work adapted a well-known recursion formula that directly uses fully normalized associated Legendre functions to compute the acceleration due to the non-sphericity of the moon. With the formulated algorithms, the states of a lunar orbiting satellite are predicted and its performance is validated in comparisons with solutions obtained from STK/Astrogator. The predicted differences in the orbital states between STK/Astrogator and the current work all remain at a position of less than 1 m with velocity accuracy levels of less than 1 mm/s, even with different orbital inclinations. The effectiveness of the current algorithm, in terms of both the computation time and the degree of accuracy degradation, is also shown in comparisons with results obtained from earlier work. It is expected that the proposed algorithm can be used as a foundation for the development of an operational flight dynamics subsystem for future lunar exploration missions by Korea. It can also be used to analyze missions which require very close operations to the moon.

• Archives of Plastic Surgery
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• v.32 no.2
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• pp.194-198
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• 2005

In many reports on the reconstruction of an orbital blowout fracture, CT(computed tomography) imaging has been used for postoperative evaluation. However, in most cases, only one plane of the CT scan was presented, which may not be sufficient for accurate evaluation. This study reviewed the CT scans presented in the related 49 articles (56 cases), and investigated our patients (150 cases) to investigate where were the most frequent unfavorable reconstructions, and to determine which planes should be presented for accurate evaluation. One plane of the CT scan was presented in 70% of the cases. On the other hand, 30% of the cases presented two planes of the CT scans. In our cases, the most prevalent sites for an unfavorable reconstruction were the posterior portion of the inferior wall, and the posterior and the inferior portion of the medial wall. In order to accurately evaluate an orbital wall reconstruction, at least two planes of a CT scan are needed. For an inferior wall evaluation, both the middle and the posterior planes of the coronal section or both the coronal and the sagittal sections are necessary. In addition, for the medial wall evaluation, both the axial and the coronal sections or both the middle and the posterior planes of the coronal section are required.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.205-207
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• 2004

The simple method of the geometric reconstruction of satellite linear pushbroom images is investigated. The model of the sensor used is based on the SPOT model that is developed by Kraiky. The satellite trajectory is a Keplerian trajectory in the approximation. Four orbital parameters, longitude of the ascending $node(\omega),$ inclination of the orbit plan(I), latitude argument of the satellite(W) and distance between earth center and satellite, are used for the camera modeling. We suppose that four orbital parameters and satellite attitude angles are exactly acquired. Then, in order to refine model, the given attitude angles and orbital parameters is not changed, but time-independent four parameters associated with LOS(Line Of Sight) vector is updated. A pair of SPOT-5 images has been used for validation of proposed method. Two GCPs acquired by GPS survey is used to controlling the LOS vector. The results are that the RMSE of 16 checking points are about 4.5m. Because the ground resolution of SPOT-5 is 2.5m, the result obtained in this study has a good accuracy. It demonstrates that the sensor model developed by this study can be used to reconstruct the geometry of satellite image taken by pushbroom camera.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.63.2-63.2
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• 2019

Eight hundred thousand asteroids in the solar system have been identified so far under extensive sky surveys. Kilometer to sub-km sized asteroids, however, are still waiting for discovery, and their size and orbital distribution will provide a better understanding of the collisional and dynamical evolution of the solar system. In order to study the number of asteroids which is detectable with 1.6 m telescope and their orbital distribution, we conducted a small observation campaign as a part of Deep Ecliptic Patrol of the Southern Sky (DEEP-South) project, which is an asteroid survey in the southern hemisphere with Korea Microlensing Telescope Network (KMTNet). We observed the ecliptic plane near opposition ($2^{\circ}{\times}2^{\circ}$ field of view centering on ${\alpha}=22h40m31s$, ${\delta}=-08^{\circ}22^{\prime}58^{{\prime}{\prime}}$) in August 2018, and identified 464 moving objects by visual inspection. As a result, 266 of 464 moving objects turn out to be previously unknown asteroids, and their signal to noise ratio is below two on numerous occasions. Most of the newly detected objects are main belt asteroids (MBAs), while three Hildas, one Jupiter trojan, and two Hungarias are also identified. In this meeting, we report the differences in the orbital distributions between the previously known asteroids and newly discovered ones using statistical methods. We also talk about the observational bias of this survey and suggest future works.

• Archives of Plastic Surgery
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• v.43 no.6
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• pp.518-522
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• 2016

Background Enophthalmos may not appear immediately after trauma due to periorbital swelling in a blowout fracture, and preoperative measurements of enophthalmos cannot be used as a reliable guideline. It is important to predict the eventual final extent of enophthalmos in order to determine whether to perform surgery, and there have been several attempts to predict the degree of late enophthalmos using preoperative orbital volume. The purpose of this study is to investigate the correlation between the orbital volume ratio (OVR) with final enophthalmos and the palpebral fissure, and to find the OVR that induced 2 mm of enophthalmos in unilateral unoperated blowout fractures. Methods We retrospectively reviewed the medical records of 38 patients and divided them into 3 groups, determined by the fracture location. The relationships between the OVR and both the degree of enophthalmos and the palpebral fissure ratio (PFR) were assessed and, in particular, the OVR that induced 2 mm of enophthalmos was sought. Results Enophthalmos increased in proportion to the OVR, and there was a highly significant correlation between the increase in the OVR and the degree of enophthalmos (P<0.05). On the other hand, there was no correlation between OVR and PFR (P>0.05). The OVR that induced 2-mm enophthalmos was 112.18%. Conclusions The final degree of enophthalmos can be estimated by the preoperative measurement of OVR. Preoperative measurements of OVR can be used as quantitative values to predict the final degree of enophthalmos in pure blowout fractures.

• Archives of Plastic Surgery
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• v.39 no.3
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• pp.204-208
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• 2012

Background : Isolated pure blowout fractures are clinically important because they are the main cause of serious complications such as diplopia and limitation of extraocular movement. Many reports have described the incidence of blowout fractures associated with diplopia and limitation of extraocular movement; however, no studies have statistically analyzed this relationship. The purpose of this study was to demonstrate the correlation between the location of isolated pure blowout fractures and orbital symptoms such as diplopia and limitation of extraocular movement. Methods : We enrolled a total of 354 patients who had been diagnosed with isolated pure blowout fractures, based on computed tomography, from June 2008 to November 2011. Medical records were reviewed, and the prevalence of extraocular movement limitations and diplopia were determined. Results : There were 14 patients with extraocular movement limitation and 58 patients complained of diplopia. Extraocular movement limitation was associated with the following findings, in decreasing order of frequency: floor fracture (7.1%), extended fracture (3.6%), and medial wall (1.7%). However, there was no significant difference among the types of fractures (P=0.60). Diplopia was more commonly associated with floor fractures (21.4%) and extended type fractures (23.6%) than medial wall fractures (10.4%). The difference was statistically significant (Bonferroni-corrected chi-squared test P<0.016). Conclusions : Data indicate that extended type fractures and orbital floor fractures tend to cause diplopia more commonly than medial wall fractures. However, extraocular movement limitation was not found to be dependent on the location of the orbital wall fracture.

• Journal of the Korean Chemical Society
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• v.29 no.1
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• pp.23-30
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• 1985

PMO expressions for ${\pi}^{\ast}$-${\pi}^{\ast}$ orbital interaction have been derived. Important differences between ${\pi}$-${\pi}$ and ${\pi}^{\ast}$-${\pi}^{\ast}$ interactions predicted by PMO expressions are : (ⅰ) energy splitting in ${\pi}^{\ast}$-${\pi}^{\ast}$ interaction will be greater than that in ${\pi}$-${\pi}$ interaction, (ⅱ) energy change due to interaction will be more destabilizing in ${\pi}^{\ast}$-${\pi}^{\ast}$ than in ${\pi}$-${\pi}$ interaction. These predictions were borne out in experimental data and in results of MO theoretical computations. It was pointed out that both STeO-3G and INDO-LCBO methods underestimate ${\pi}^{\ast}$-${\pi}^{\ast}$ orbital interaction and in order to estimate properly with MO theoretical calculation, use of split valence basis set is required.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.205-213
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• 2009

This study reports on the geometry optimizations and electronic structure calculations for methyl pyropheophorbide (MPPa), tropolonyl methyl pyropheophorbides (TMPPa, ITMPPa), and cationic tropolonyl methyl pyropheophorbides ($TMPPa^+{{\cdot}BF_4}^-,\;ITMPPa^+{{\cdot}BF_4}^-,\;TMPPa^+,\;and\;ITMPPa^+$) using Local Spin Density Approximation (LSDA/ 6-31G*) and the Restricted Hatree-Fock (RHF/6-31G*) level theory. From the calculated results, we found that substituted cationic tropolonyl groups have larger structural effects than those of substituted neutral tropolonyl groups. The order of structural change effects is $ITMPPa^+ > ITMPPa^+{{\cdot}BF_4}^-$ > ITMPPa, as a result of the isopropyl group. Because it is an electron-releasing group, the substituted isopropyl group electronic effect on a 3-position tropolone increases the Highest Occupied Molecular Orbital and Lowest Unoccupied Molecular Orbital (HOMO-LUMO) energy gap. It was constituted that the larger the cationic characters of these photosensitizers, the smaller the HOMOLUMO band gaps are. The orbital energies of the cationic systems and the ions are stronger than those of a neutral system because of a strong electrostatic interaction. However, this stabilization of orbital energies are counteracted by the distortion of chlorin macrocycle, which results in a large destabilization of chlorin-based compound HOMOs and smaller destabilization of LUMOs as shown in TMPPa (ITMPPa), $TMPPa^+{{\cdot}BF_4}^- (ITMPPa^+{{\cdot}BF_4}^-),\;and\;TMPPa^+\;(ITMPPa^+)$ of Figure 6 and Table 6-7. These results are in reasonable agreement with normal-coordinate structural decomposition (NSD) results. The HOMO-LUMO gap is an important factor to consider in the development of photodynamic therapy (PDT).

• Journal of the Korean Electrochemical Society
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• v.16 no.3
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• pp.177-183
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• 2013

As the development of available binder in the harsh conditions is needed, we propose the proper binder for high-voltage lithium-ion secondary batteries based on the quantum chemistry modeling. The optimized structures, HOMO (Highest Occupied Molecular Orbital) energies and ionization potentials of 4 binders, which were considered from monomer to tetramer, were investigated by the semi-empirical and DFT (Density Functional Theory) calculations. The results show that the ionization potential values by calculation tend to be close to the oxidation potentials from the measurement of linear sweep voltametry (LSV). The order of oxidative resistance from high value to low value is following: poly(hexafluropropylene), poly(vinylidene fluoride), poly(methyl acrylate) and poly(acryl amide). Also these results correspond with the experimental values. Thus, we find the reason why HOMO (Highest Occupied Molecular Orbital) energy of PHFP has the highest value than other binders by analysis of HOMO orbital structures.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.60-65
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• 2014

In this paper, numerical integration method using operational matrix of integration is studied. Using the operational matrix of integration, modified fixed point iteration method is introduced in order to solve rapidly an initial value problem for non-linear equation of motion. As an example, an initial value problem for orbital motion is considered. Through the numerical example, it is shown that the algorithm is efficient from the computational time point of view.