• Title/Summary/Keyword: Mass function

Search Result 2,109, Processing Time 0.037 seconds

A New Perspective on the Blue Tilt Phenomenon of Extragalactic Globular Cluster Systems

  • Lee, Sang-Yoon;Yoon, Suk-Jin
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.35 no.2
    • /
    • pp.29.1-29.1
    • /
    • 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.

  • PDF

Comparison of CME mean density based on a full ice-cream cone structure and its corresponding ICME one

  • Na, Hyeonock;Moon, Yong-Jae
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.43 no.1
    • /
    • pp.54.1-54.1
    • /
    • 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.

  • PDF

Proximal Flexor Hallucis Longus Tendon Transfer for the Ossification of the Achilles Tendon (A Case Report) (근위 장 무지 굴근건 이전술을 이용한 아킬레스건 골화증의 치료(1예 보고))

  • Kim, Hyong-Nyun;Jo, Min-Young;Park, Yong-Wook
    • Journal of Korean Foot and Ankle Society
    • /
    • v.15 no.2
    • /
    • pp.110-113
    • /
    • 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.

Discrete Optimal Design of Composite Rotor Blade Cross-Section (복합재 로터 블레이드 단면 이산최적설계)

  • Won, You-Jin;Lee, Soo-Yong
    • Journal of the Korean Society for Aviation and Aeronautics
    • /
    • v.21 no.2
    • /
    • pp.7-14
    • /
    • 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.

UBV CCD PHOTOMETRY OF INTERMEDIATE AGE OPEN CLUSTER M11 I. STATISTICAL ANALYSIS

  • SUNG HWANKYUNG;LEE SEE-WOO;LEE MYUNG GYOON;ANN HONG BAE
    • Journal of The Korean Astronomical Society
    • /
    • v.29 no.2
    • /
    • pp.269-278
    • /
    • 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.

  • PDF

Application of Iterative Learning Control to 2-Mass Resonant System with Initial Position Error (위치 오차를 갖는 2관성 공진계에 대한 반복학습 제어의 적용에 관한 연구)

  • Lee, Hak-Seong
    • Proceedings of the KIEE Conference
    • /
    • 2003.11b
    • /
    • pp.307-310
    • /
    • 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.

  • PDF

Optimal Design of Composite Rotor Blade Cross-Section using Discrete Design variable (이산설계변수를 고려한 복합재 로터블레이드 단면 최적설계)

  • Won, You-Jin;Lee, Soo-Yong
    • Journal of Aerospace System Engineering
    • /
    • v.8 no.1
    • /
    • pp.12-17
    • /
    • 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.

Thermodynamics of Mixtures (I). Ideal Gases (혼합물의 열역학 (제1보). 이상기체)

  • C. K. Yun
    • Journal of the Korean Chemical Society
    • /
    • v.17 no.5
    • /
    • pp.324-331
    • /
    • 1973
  • We study a mixture of ideal gases by use of recently developed methods in continuum thermodynamics of irreversible processes. A complete form of the free energy function and the gas law for each component are derived directly from an entropy production inequality by assuming that: (1) Constitutive functions depend on the mass densities, the diffusion velocities, the temperature and its gradient only. (2) Phenomenological coefficients appearing in an extra entropy flux are material constants. (3) The internal energy density per unit mass is independent of the total mass density (Joule).

  • PDF

A Case of Ectopic Thyroid with Clinical Evaluation of Fifteen Cases (이소성 갑상선 1례 및 국내 증례의 임상적 고찰)

  • 고중화;안성윤;송정환;박승구
    • Korean Journal of Bronchoesophagology
    • /
    • v.5 no.1
    • /
    • pp.55-61
    • /
    • 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.

  • PDF

The Effect of the Boundary Condition on the Added Mass of a Rectangular Plate (직사각형판(直四角形板)의 탄성접수진동(彈性接水振動)에서 주변지지조건(周緣支持條件)의 영향(影響))

  • K.C.,Kim;J.S.,Kim
    • Bulletin of the Society of Naval Architects of Korea
    • /
    • v.15 no.2
    • /
    • pp.1-11
    • /
    • 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.

  • PDF