• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.29.3-29.3
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• 2017

We study the connection between the observed star formation rate-stellar mass (SFR-M) relation and the evolution of the stellar mass function (SMF) by means of a Subhalo Abundance Matching technique coupled to merger trees extracted from a N-body simulation. Our approach, which considers both galaxy mergers and stellar stripping, is to force the model to match the observed SMF at redshift z>2, and let it evolve down to the present time according to the observed (SFR-M) relation. In this study, we use two different sets of SMFs and two SFR-M relations: a simple power law and a relation with a mass-dependent slope. Our analysis shows that the evolution of the SMF is more consistent with a SFR-M relation with

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.52.1-52.1
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• 2011

We have implemented the Smoothed Particle Hydrodynamics (SPH) into the cosmological N-body simulation code. The pre-initial particle distribution is set to follow the glacial conditions and the initial temperature of hydro particles is calculated based on the adiabatic process in the expanding backgrounds. Typical adiabatic SPH equations are adopted and, additionally, non-adiabatic processes such as heating/cooling and supernova explosion are added. We study the effect of star formation criteria on the global star formation rate and compare it with the observations.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.211-214
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• 2015

We investigated the period variation for 79 eclipsing binary systems using 20 years (1990-2009) of EROS, Macho, and OGLE survey observations. We discovered 9 apsidal motions, 8 mass transfers, 5 period increasing and decreasing systems, 12 light-travel-time effects, 5 eccentric systems and 40 other systems showing no period variations. We select 3 representative eclipsing binary systems; EROS 1052 for apsidal motion, EROS 1056 for mass transfer, and EROS 1037 for the light-travel-time effect. We determine the period variation rate (dP/dt), orbital parameters of the 3rd body (e3, ${\omega}_3$, $f(m_3)$, $P_3$, $T_3$), apsidal motion parameters ($d{\omega}/dt$, U, Ps, Pa, e) and apsidal motion period by analyzing the light curves and O-C diagrams.

• Journal of The Korean Astronomical Society
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• v.2 no.1
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• pp.1-9
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• 1969

On the instantaneous tidal relaxation approximation, formulae are derived for the ellipticities and virial theorem of a slightly flattened homogeneous rotating cluster (the largest axis of the cluster is directed towards the Galactic center), in terms of the Galactic tidal force and the characteristic intrinsic plus orbital angular velocity. The expression for a purely tidally-determined ellipticity is identical to that for an incompressible fluid body of uniform density. Orbital motion generally contributes significantly to the shape of the cluster. The virial theorem is identical to that for an isolated cluster except that the gravitational potential energy is multiplied by (1-${\chi}$), where ${\chi}$ is a positive tidal correction term. To obtain the actual mass of a cluster, the virial theorem mass based on an isolated cluster should be multiplied by the factor 1/(1-${\chi}$). The formulae are applied to open star clusters, the globular cluster ${\omega}$ Centauri, and dwarf elliptical galaxies in the Local Group.

• Animal Systematics, Evolution and Diversity
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• v.38 no.4
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• pp.157-161
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• 2022

Parartotrogus minutus n. sp. is described as a parasite of the brittle star Ophiuroglypha kinbergi (Ljungman) from the intertidal zone on the Yellow Sea coast of Korea. The new species is characterized by a combination of morphological features that the body is small, less than 0.5 mm long, the caudal ramus is 1.73 times longer than wide, leg 3 bears three-segmented rami, and the exopod of leg 5 is armed with two setae. The new species is the third known species in the genus, following P. richardi Scott T. and Scott, A., 1893 known from European waters and P. arcticus Scott T., 1901 known from both North Atlantic and North Pacific.

• Animal Systematics, Evolution and Diversity
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• v.39 no.3
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• pp.127-132
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• 2023

Aquilonastra doranae, a newly recorded sea star, was collected from the southern coast of Jejudo Island by a trimix SCUBA diving survey in May 2021. The newly collected specimen is distinguished from a previously known Aquilonastra species in South Korea by having a fissiparous body form with six arms. Results of pairwise genetic distance analysis showed that the new specimen was identical or close to A. anomala from Hawaii (0.0%), Australia (3.1%), and Samoa (3.3%). However, morphological characteristics of the Korean Aquilonastra specimen corresponded with the original description of A. doranae, not that of A. anomala, including the number of inferomarginal spines, the absence of pedicellariae, and the inhabit locality. Thus, this study agrees with the original morphological study of A. doranae and presents this specimen as the first record of A. doranae in South Korea.

• Archives of Plastic Surgery
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• v.46 no.5
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• pp.462-469
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• 2019

Background Incisional hernia is a common complication following visceral organ transplantation. Transplant patients are at increased risk of primary and recurrent hernias due to chronic immune suppression and large incisions. We conducted a retrospective review of patients with a history of liver or kidney transplantation who underwent hernia repair to analyze outcomes and hernia recurrence. Methods This is a single center, retrospective review of 19 patients who received kidney and/or liver transplantation prior to presenting with an incisional hernia from 2011 to 2017. All hernias were repaired with open component separation technique (CST) with biologic mesh underlay. Results The mean age of patients was $61.0{\pm}8.3years\;old$, with a mean body mass index of $28.4{\pm}4.8kg/m^2$, 15 males (78.9%), and four females (21.1%). There were seven kidney, 11 liver, and one combined liver and kidney transplant patients. The most common comorbidities were hypertension (16 patients, 84.2%), diabetes (9 patients, 47.4%), and tobacco use (8 patients, 42.1%). Complications occurred in six patients (31.6%) including hematoma (1/19), abscess (1/19), seroma (2/19), and hernia recurrence (3/19) at mean follow-up of $28.7{\pm}22.8months$. With the exception of two patients with incomplete follow-up, all patients healed at a median time of 27 days. Conclusions This small, retrospective series of complex open CST in transplant patients shows acceptable rates of long-term hernia recurrence and healing. By using a multidisciplinary approach for abdominal wall reconstruction, we believe that modified open CST with biologic mesh is a safe and effective technique in the transplant population with complex abdominal hernias.

• Journal of the Korean Society of Physical Medicine
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• v.18 no.1
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• pp.37-50
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• 2023

PURPOSE: This study examined the effects of various interventions for improving the hip joint range of motion on elite badminton players, including body balance ability, jumping power, smash speed, and joint range of motion. METHODS: The study was conducted on elite badminton players belonging to the S badminton team in Yongin, Gyeonggi-do, and the M badminton team in Suwon, Gyeonggi-do. Twenty-one elite badminton players were selected; they were assigned randomly to Experimental Group 1 (n = 11) and Experimental Group 2 (n = 10). Before and after the intervention, the hip joint range of motion, modified star excursion balance test, Sargent jump, and smash speed were measured. In Experimental Group 1, hip joint manual mobilization was applied by a physical therapist, and hip self-exercise performed by the athletes was applied in Experimental Group 2. This intervention was applied once a day, three times a week, for four weeks. RESULTS: A significant increase in the hip joint range of motion (flexion and extension) and modified star excursion balance test (posteromedial direction) was observed in Experimental Group 1 (hip joint mobilization applied group) compared to Experimental Group 2 (hip joint self-exercise applied group) (p < .05). CONCLUSION: When elite level badminton players require improvement in hip flexion and extension range of motion and posteromedial body balance, hip joint mobilization is more effective than hip self-exercise application.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.56.1-56.1
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• 2011

To understand the effect of the initial rotation for tidally bounded clusters with mass spectrum, we performed N-body simulations for the clusters with different degrees of initial rotation and compared to Fokker-Planck results. We confirmed that the cluster evolution is accelerated by the initial rotation as well as the mass spectrum. For the slowly rotating models, the time evolution of mass, energy and angular momentum show good agreements between N-body and Fokker-Planck calculations. On the other hand, for the rapidly rotating models, there are significant differences between two approaches at the beginning of the evolution. By investigating cluster shapes, we concluded that these differences are mainly due to secular instability that takes place for very rapidly rotating clusters. The shape of cluster for N-body simulations becomes tri-axial or even prolate, while the 2-dimensional Fokker-Planck simulation can treat only oblate type axisymmetric systems. We also founded that there is the angular momentum exchange from high mass to low mass.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.961-967
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• 2019

This research presents an efficient method based on computational fluid dynamics (CFD) for estimating the resistance performance of a ship with a large settlement amount and a dynamic trim. The settlement of the inviscid flow analysis and the results of dynamic trim were used to set a large attitude for the ship prior to performing a viscous flow analysis; a viscous flow analysis was subsequently performed by Dynamic Fluid Body Interaction (DFBI). This method is termed as method I, in which a simple grating system can be used without employing the overset mesh technique by setting many attitudes before interpretation. Thus, method I is advantageous in reducing calculation time and improving calculation accuracy. The viscous flow analysis was performed using a commercial CFD code STAR-CCM+. Compared with the final convergence result, the first viscous flow analysis result of method I exhibited a variation of less than 1 % of resistance. The result was obtained by changing the gratings each time an attitude is changed at each calculation stage, based on the DFBI method provided to STAR-CCM+ using a simple grating system, which is not a superposed grating. This method is termed as method II. Compared with method II of resistance, method I exhibited a dif erence of 0.03-0.6 % for linear velocity. The results of method I were confirmed to be qualitatively and quantitatively appropriate through comparison with several trillion simulations.