• 천문학회보
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• 제44권2호
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• pp.73.4-73.4
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• 2019

Most of the galaxy mass is known to be occupied by dark matter. However, it is difficult to directly measure the mass and distribution of dark matter in a galaxy. Recently, the velocity dispersion of the stellar population in a galaxy's center has been suggested as a possible probe of the mass of the dark matter halo. In this study, we test and verify this hypothesis using the kinematics of the satellite galaxies of isolated galaxies. We use the Friends-of-Friends (FoF)algorithm to build a catalog of primary galaxies and their satellite galaxies from the Sloan Digital Sky Survey (SDSS) DR 12. We calculate the dynamical mass of the primary galaxies from the velocity dispersion of their satellite galaxies. We then investigate the correlation between the dynamical mass and the central velocity dispersion of the primary galaxies. The stellar velocity dispersion of the central host galaxies has a strong linear correlation with the velocity dispersion of their satellite galaxies. Also, the stellar velocity dispersion of the central galaxy is strongly correlated with the dynamical mass of the galaxy, which can be described as a power law. The results of this study show that the central velocity dispersion of the primary galaxies is a good proxy for tracing the mass of dark matter halo.

• 한국방재안전학회논문집
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• 제10권1호
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• pp.75-84
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• 2017

내풍설계에서 기본풍속의 경우 우리나라는 10분 평균풍속을 이용하고 있지만, 기후변화와 태풍의 직간접 영향 및 강도증가로 인한 순간최대풍속이 구조물에 미치는 영향이 더 크다는 사실이 알려지고 있고, 일부 다른 나라에서는 이러한 순간풍속의 효과를 고려 3초의 평균풍속을 이용하고 있다. 본 논문에서는 1973-2016연까지의 일순간최대풍속의 확률과정, 통계적 성질, 난류의 특성 등을 평가하기 위하여 대표지점(17개 지점)을 선정했다. 선정된 각 지점에 대한 일순간최대풍속자료는 기상청으로부터 획득했다. 획득된 순간풍속의 해석결과 다음과 같은 결론을 얻었다. 1. 제주 서귀포 여수 부산에서의 8 7 9월에 0.2~0.35%로 나타났고, 서울 대관령은 3 4 5월에 0.25%로 나타났다. 2. 확률과정의 왜도평가에서 해안지역보다는 내륙지역에서의 더 큰 비정규성을 나타냈다. 3. 인접지역의 상관계수 평가에서 서울 인천(0.8), 대전 청주(0.75), 제주 서귀포(0.72) 순으로 나타났으며, 대관령 강릉은(-0.07), 전주 군산(0.0)은 인접지역의 영향이 거의 없는 것으로 나타났다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1991년도 춘계학술대회
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• pp.9-12
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• 1991

The correlation search method yields velocity information by tracking scatter patterns between medical image frames. The displacement vector between a target region and the best correlated search region indicates the magnitude and direction of the inter-frame motion of that particular region. However, if the noise sources in the target region and the search region are correlated Gaussian, then the cross-correlation technique fails to work well because it estimates the cross-correlation of both signals and noises. In this paper we develop a new correlation search method which seeks the best correlated third-order statistics between a target and the search region to suppress the effect of correlated Gaussian noise sources. Our new method yields better estimations of velocity than the conventional cross-correlation method.

• Journal of Advanced Marine Engineering and Technology
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• 제20권5호
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• pp.30-38
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• 1996

A PIV system consisting of an image board slit into personal computer and 2-D sheet light projector is developed and related techniques to improve its performance are discussed. A grey-level cross correlation method capable of overcoming particle seeding limitation is suggested. And a sub-pixed interpolation method in determining the vector terminal is preposed by considering 8-neighbours correlation distributing patterns. Furthermore, pressure estimation from the acquired velocity vectors by applying the Poisson equation is persented with reasonable feasibility. As a practical application of the present system, evaporator flows are analysed and attained instantaneous velocity vectors reveal that the flow phenomena maintain turbulent fluctuation.

• 대한기계학회논문집B
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• 제29권7호
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• pp.837-845
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• 2005

In this paper, an investigation on high-Schmidt number (Sc=1670) mass transfer in turbulent flow around a rotating circular cylinder is carried out by Direct Numerical Simulation. The concentration field is computed for three different values of low Reynolds number, namely 161, 348 and 623 based on the cylinder radius and friction velocity. Statistical study reveals that the thickness of Nernst diffusive layer is very small compared with that of viscous sub-layer in the case of high Sc mass transfer. Strong correlation of concentration field with streamwise and vertical velocity components is observed. However, that is not the case with the spanwise velocity component. Instantaneous concentration visualization reveals that the length scale of concentration fluctuation typically decreases as Reynolds number increases. Statistical correlation between Sherwood number and Reynolds number is consistent with other experiments currently available.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.90-97
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• 2003

The purpose of this study is to understand the dissipation pattern of excess pore pressure after liquefaction which governs the post-liquefaction behavior of liquefied sand deposits. 1-g shaking table tests were carried out on 5 different kinds of sands, all of which had high liquefaction potentials. During the tests excess pore pressure at various depths, and surface settlements were measured. The measured curve of the excess pore pressure dissipation was simulated using the solidification theory, and from the analysis of the velocity of dissipation, the dissipation pattern of excess pore pressure after liquefaction was examined. The dissipation velocity of excess pore pressure after liquefaction had a linear correlation with the effective grain size ( $D_{10}$) divided by the coefficient of uniformity ( $C_{u}$), and the increase in the initial relative density of the ground played a role in shifting this correlation curve toward an increased dissipation velocity. From the correlation, an approximate method was recommended for prediction of the dissipation curve of excess pore pressure after liquefaction in saturated sand deposits.s.s.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.77-78
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• 2015

Laminar burning velocities have been predicted by constant volume combustion chamber, counter flow burner and others. In this study, the measured flame propagation velocities in an assembled annular stepwise diverging tube were plotted with respect to equivalence ratio, length scale, and velocity scale. Three dimensional approach to understand the flame propagation velocity including laminar burning velocity is investigated, and the surface provides the correlation among quenching distance, propagation velocity, and equivalence ratio.

• PNF and Movement
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• 제8권3호
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• pp.39-47
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• 2010

Purpose : The purpose of this study was to investigate the correlations between clinical balance scales and Balance Performance Monitor parameters in patient with adolescent idiopathic scoliosis (AIS). Methods : Twenty AIS subjects (age, $14.26{\pm}1.93yrs$; height, $160.56{\pm}7.98cm$; weight, $47.54{\pm}6.94kg$)were participated in this study. Postural sway(mean balance, sway angle, sway area, sway path, maximal sway velocity) were were evaluated by balance performance monitor. Measurements for clinical balance scales were Functional reach test (both side), the Lateral reach test (both side) and One leg standing test (both legs). Results : The results were as follows. There were positive strong correlation between major curve direction and left-right sway angle, sway path, maximal sway velocity. There were negative strong correlation between the functional reach and left-right sway angle, sway area, sway path, maximal sway velocity. And the lateral reach were also showed negative strong correlation parameters of balance performance monitor. One leg standing were negatively correlated with left-right sway angle, sway path, maximal sway velocity. Conclusion : The clinical balance scales will be useful tools for balance measurements, and basic tools for clinical setting for patient with AIS.

• 국제물리치료학회지
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• 제9권4호
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• pp.1602-1607
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• 2018

This study examined the correlation between power error (PE) and velocity error (VE) according to the condition and frequency of self-controlled feedback (SCF) during knee extension. One hundred participants were randomly assigned to 30% SCF, 70% SCF, 30% yoked feedback (YF), 70% YF and control group, respectively. The SCF group was provided with feedback when they requested it, whereas the YF group did not influence the feedback schedule. Participants in the control group were not given any visual feedback during the experiment. The isotonic, isometric, and isokinetic dynamometer (PRIMUS RS, BTE, USA) was used to measure the power and velocity error during knee extension. The collected data was analyzed using a Pearson test and SPSS 21.0. The correlation between PE and VE according to the condition and frequency of feedback on each phase during knee extension was significant. Both PE and VE were significantly higher when the feedback was provided with high frequency, passive, and no feedback. Our study suggests that application of SCF can help to improve the proprioception of the healthy person while reducing errors through low frequency and active feedback.

• 대한기계학회논문집
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• 제11권1호
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• pp.88-96
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• 1987

본 논문에서는 Maubach의 방법에 내재된 불합리한점을 보완하고자 Fig.1(b)와 같이 .iota.=0인 곳에서 속도구배를 ㄹ변환하여 마찰계수와 조도함수를 계산하였다. 이 방법에 의해 얻어진 속도분포에서는 .iota.=0인 곳에서 속도구배에 불연적성이 일어나지 않는다.