• 천문학회보
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• 제35권2호
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• pp.29.1-29.1
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• 2010

Recent observations reveal that some early-type galaxies show a color-magnitude relation of blue globular clusters (GCs) in the color-magnitude diagrams, which is referred to as 'blue tilt'. This phenomenon is interpreted as a mass-metallicity relation -- metallicities of blue GCs increase with increasing mass, and thus provides a crucial clue to the chemical enrichment processes of GCs as a function of their mass. However, some galaxies show 'non-tilt' or even 'reverse blue tilt' on the blue GC sequence, and thus the origin of blue tilt still remains a puzzle. In this study, we put forward the theoretical explanation for the phenomenon and discuss its implications towards galaxy formation scenarios.

• 천문학회보
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• 제43권1호
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• pp.54.1-54.1
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• 2018

For space weather forecast, it is important to determine three-dimensional parameters of coronal mass ejections (CMEs). To estimate three-dimensional parameters of CMEs, we have developed a full ice-cream cone model which is a combination of a symmetrical flat cone and a hemisphere. By applying this model to 12 SOHO/LASCO halo CMEs, we find that three-dimensional parameters from our method are similar to those from other stereoscopic methods. For several geoeffective CME events, we determine CME mass by applying the Solarsoft procedure (e.g., cme_mass.pro) to SOHO/LASCO C3 images. CME volumes are estimated from the full ice-cream cone structure. We derive CME mean density as a function of CME height for these CMEs, which are approximately fitted to power-law functions. We find that the ICME mean densities extrapolated from the power law functions, are correlated with their corresponding ICME ones in logarithmic scales.

• 대한족부족관절학회지
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• 제15권2호
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• pp.110-113
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• 2011

Ossification of the Achilles tendon is a rare condition that is characterized by the presence of an ossific mass contained within the substance of the tendon. The ossified mass is usually asymptomatic but when it grows large and painful, it deteriorates the function of Achilles tendon. We report a case of ossification of the Achilles tendon, which was successfully treated by removal of the ossific mass and proximal flexor hallucis longus (FHL) tendon transfer.

• 한국항공운항학회지
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• 제21권2호
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• pp.7-14
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• 2013

In this paper, the optimal design of composite rotor blade cross-section is performed using a genetic algorithm. Skin thickness, torsion box thickness and skin lay-up angle are adopted as discrete design variables. The position and width of a torsion box are considered as continuous variables. An object function of optimal design is to minimize the mass of a rotor blade, and constraints are failure index, center mass, natural frequency and blade minimum mass per unit length. Finally, design variables such as the thickness and lay-up angles of a skin, and the thickness, position and width of a torsion box are determined by using an in-house program developed for the optimal design of rotor blade cross-section.

• 천문학회지
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• 제29권2호
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• pp.269-278
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• 1996

We present the color-magnitude diagrams (CMD) of more than 24,000 stars in the field of an intermediate age open cluster M11, based on wide field CCD imaging. The morphology of the CMDs varies strikingly as the distance from the center of the cluster increases. From the surface number density analysis, we confirm the mass segregation effect in this cluster: the bright, massive stars are centrally more concetrated than the faint, low mass stars. The slope of the field-corrected surface density with respect to magnitude progressively increases as the radius increases, up to r = 5'. Most of the field stars in or near the cluster main sequence band and in the bright part of the red stars in the CMDs appear to be nearly at the same distance as M11, and they are considered to be the major component of disk stars in the Sagittarius-Carina arm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.307-310
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• 2003

In this paper, an iterative learning control method is applied to suppress the vibration of a 2-mass system which has a flexible coupling between a load an a motor. More specifically, conditions for the load speed without vibration are derived based on the steady-state condition. And the desired motor position trajectory is synthesized based on the relation between the load and motor speed. Finally, a PD-type learning iterative control law is applied for the desired motor position trajectory. Since the learning law applied for the desired trajectory guarantees the perfect tracking performance, the resulting load speed shows no vibration. In order to handle the initial position error, the PD-type learning law is changed to PID-type and a weight function is added to suppress the residual vibration caused by the initial error. The simulation results show the effectiveness of the proposed learning method.

• 항공우주시스템공학회지
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• 제8권1호
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• pp.12-17
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• 2014

In this paper, optimal design of composite rotor blade cross-section to consider manufacturability was performed. Skin thickness, torsion box thickness and skin lay-up angle were adopted as discrete design variables and The position and width of a torsion box were considered as continuous variables. An object function of optimal design is to minimize the mass of a rotor blade, and various constraints such as failure index, center mass, shear center, natural frequency and blade minimum mass per unit length were adopted. Finally, design variables such as the thickness and lay-up angles of a skin, and the thickness, position and width of a torsion box were determined by using an in-house program developed for the optimal design of rotor blade cross-section.

• 대한화학회지
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• 제17권5호
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• pp.324-331
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• 1973

이상기체 혼합물을 연속체의 물질역학과 비가역 변화의 열역학에서 개발된 방법으로 연구하였다. 자유 에너지의 함수 형태와 각개 성분의 기체법칙을 엔트로피 부등식으로부터 직접 유도하고 혼합물의 변형, 열 전도, 확산 및 화학반응이 받는 제약을 명시함으로서 앞으로 이 방법을 다른 물질들에 응용하는 데에 도움이 되도록 하였다.

• 대한기관식도과학회지
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• 제5권1호
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• pp.55-61
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• 1999

The authors recently experienced a case of ectopic thyroid. A 15-year-old female patient visited to ENT department with the complaint of the submental neck mass. On physical examination, the mass was relatively firm, non tender and 3$\times$2cm in size. Oral cavity examination revealed 0.5$\times$0.5cm sized pink colored mass near the foramen cecum area. Suspecting ectopic thyroid, thyroid function test, thyroid scan, neck computed tomogram scan were performed. Thyroid scan revealed a functioning thyroid on the lingual and submental area without normal uptake in the anterior neck area. Thyroid (unction test was normal. Pre-contrast computed tomogram scan revealed an ectopic thyroid in the lingual and submental area. A review of literature concerning ectopic thyroid was discussed.

• 대한조선학회지
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• 제15권2호
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• pp.1-11
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• 1978

Using the elliptical cylindrical function, the added masses of thin rectangular plates vibrating elastically in an infinite ideal fluid are calculated. For the boundary conditions of the plates, two models are adopted. The plate which is simply-supported on two opposite edges while the other edges are clamped is one and the other is the plate which is simply-supported on two opposite edges while the other edges are free. Same examples are calculated numerically for the fundamental mode in each cases. And the effect of the boundary condition on the added mass are investigated by comparing these data with those of Kim's[4] which were calculated for the simply-supported plates by the same method. It is concluded that it is possible to predict the added mass of a rectangular plate, whose boundary condition is not treated in this report, by using the result of this investigation.