• 한국운동역학회지
• /
• 제13권1호
• /
• pp.185-204
• /
• 2003

The purpose of this study was to obtain the data for stable and accurate techniques of the free throw in basketball. The subjects of this study were seven male basketball player consisted of college students athletes. Free throw motions were taken by video camera. The three-dimensional coordinates was processed by DLT. The variables were the velocity, the angular velocity of the upper extremity segments, degree, and angular momentum. The result of analysis is summarized as follows. 1. The velocity and angular velocity of the upper extremity segment was showed an gradual increase and a smooth velocity transfer, transferring from proximal segment to distal segment at free throw motion in basketball. 2. The local term and remote term angular velocity momentum of the proximal segment showed larger than that of the distal segment in X, Y, Z axis component all. 3. The remote term angular momentum was showed larger than that of the local term angular momentum in X, Y, Z axis component all. 4. The angular motion of the upper trunk and upper arm, upper arm and forearm was showed in opposite direction and symmetrical angular momentum in local term angular momentum of the Y and Z axis component. 5. All the segments of upper extremity segment was showed left rotation in remote term angular momentum of the Y axis component and right rotation in remote term angular momentum of the Z axis component.

• 한국운동역학회지
• /
• 제14권3호
• /
• pp.119-134
• /
• 2004

The purpose of this study was to analyze the angular momentum characteristics of the Fosbury Flop high jump and the role of the body segments for the production of 3 angular momentum components. The subjects were three male jumpers who were former Korean national team players. Their jumping motions were analyzed using the DLT method of three-dimensional cinematography. The conclusions were as follows. 1. All the forward angular momentum needed to clear the bar was created in the take-off phase. Take-off leg was the great contributor of the forward angular momentum. On the other hand, free leg produced large opposite angular momentum. 2. All subject had some lateral angular momentum before the take-off phase. Head and free leg had major contribution to the lateral angular momentum production. Take-off leg produced opposite angular momentum. 3. All subject had some twisting angular momentum, which make the back of the athlete him to the bar, before the take-off phase. Free leg was the major contributor of the twisting angular momentum. Head and trunk was the second contributor of the twisting angular momentum. 4. Total angular momentum needed to clear the bar had no significant correlation to the jumping height. 5. Subject who made excessive angular momentum showed different pattern of angular momentum production and had a poor record compared to other subject.

• 한국과학교육학회지
• /
• 제12권1호
• /
• pp.11-21
• /
• 1992

This study tried to find out the effect to types of test items upon the momentum effect. The previous studies showed that the momentum effect is influenced by stduents' congnitive levels and the abstractness of test items. In this study focused on the types of test items The test items are divided into 4 different types of quantitative and qualitative, verbal and image. The result showed that qualitative items showed a longer momentum effect than quantitative ones. The image items and verbal items did not show significant difference in the duration of momentum effect. The interpretation of this would need a careful psychological analysis. Anyhow, this result reconfirmed the existence of the momentum effect and showed that the study on the momentum effect could be a Significant research paradigm.

• Journal of the Korean Data Analysis Society
• /
• 제20권6호
• /
• pp.3025-3035
• /
• 2018

본 연구는 대만증권거래소에 상장된 종목을 대상으로 하여 모멘텀 현상이 어떠한 경우에 나타나는지를 분석한다. 특히, 기업 규모, 외국인 투자자 지분율, 개인 투자자 지분율, 기관 투자자 지분율에 따른 모멘텀 현상의 차이에 대해 살펴보는 것이 본 연구의 목적이다. 대만 주식시장에서 모멘텀 현상을 실증 분석한 결과는 다음과 같다. 첫째, 전체 표본 기간 동안 모멘텀 현상이 존재하지 않는 것으로 나타났다. 둘째, 기업 규모별로 나누어도 모멘텀 전략의 수익성이 존재하지 않는 것으로 드러났다. 그러나 지분율에 따라 세부적으로 나누면 결과는 달라진다. 셋째, 개인 투자자 지분율이 높은 기업에는 유의적인 양(+)의 모멘텀이 존재하는 것으로 드러났다. 따라서 기관 투자자 지분율이 낮은 기업에서는 양(+)의 모멘텀을 관찰할 수 있다. 마지막으로, 외국인 지분율에 따라 나눌 경우 모멘텀 현상이 나타나지 않았다. 본 연구는 기존 연구들과 달리 대만 주식시장에서 외국인 투자자의 지분율뿐만 아니라 개인 투자자 및 기관 투자자 지분율과 모멘텀 현상 간의 관계에 대해 추가적인 실증분석을 실행하였다는 점에 있어서 학술적 공헌을 가진다.

• Nuclear Engineering and Technology
• /
• 제33권4호
• /
• pp.409-422
• /
• 2001

The dynamic character of a system of the governing differential equations for the one- dimensional two-fluid model, where the momentum flux parameters are employed to consider the velocity and void fraction distribution in a flow channel, is investigated. In response to a perturbation in the form of a＇traveling wave, a linear stability analysis is peformed for the governing differential equations. The expression for the growth factor as a function of wave number and various flow parameters is analytically derived. It provides the necessary and sufficient conditions for the stability of the one-dimensional two-fluid model in terms of momentum flux parameters. It is demonstrated that the one-dimensional two-fluid model employing the physical momentum flux parameters for the whole range of dispersed flow regime, which are determined from the simplified velocity and void fraction profiles constructed from the available experimental data and $C_{o}$ correlation, is stable to the linear perturbations in all wave-lengths. As the basic form of the governing differential equations for the conventional one-dimensional two-fluid model is mathematically ill posed, it is suggested that the velocity and void distributions should be properly accounted for in the one-dimensional two-fluid model by use of momentum flux parameters.s.

• 한국운동역학회지
• /
• 제14권3호
• /
• pp.165-175
• /
• 2004

The aim of this study is to show the effect of starting block angle on the starting motion of sprinters using a crouching start. After installing starting blocks on forced platform, and having four highly comparative sprinters use the starting blocks, I analyzed the angular momentum of a crouching start. From the results of the analysis, the following conclusions could be drawn: There were differences of angular momentum both in body's X, Y, and Z axes and in the thighs' X axes, but not in the pelvis and lower legs. As to the general change of block angle, we noticed that an angular momentum for each segments was higher at an angle of 50 to 55 degrees.

• 대기
• /
• 제23권1호
• /
• pp.1-11
• /
• 2013

The angular momentum transport of an idealized axisymmetric vortex in the developing stage was investigated using the Weather Research and Forecast (WRF) model. The balanced axisymmetric vortex was constructed based on an empirical function for tangential wind, and the temperature, geopotential, and surface pressure were obtained from the balanced equation. The numerical simulation was carried out for 6 days on the f-plane with the Sea Surface Temperature (SST) set as constant. The weak vortex at initial time was intensified with time, and reached the strength of tropical cyclone in a couple of days. The Absolute Angular Momentum (AAM) was transported along with the secondary circulation of the vortex. Total AAM integrated over a cylinder of radius of 2000 km decreased with simulation time, but total kinetic energy increased rapidly. From the budget analysis, it was found that the surface friction is mainly responsible for the decrease of total AAM. Also, contribution of the surface friction to the AAM loss was about 90% while that of horizontal advection was as small as 8%. The trajectory of neutral numerical tracers following the secondary circulation was presented for the Lagrangian viewpoint of the transports of absolute angular momentum. From the analysis using the trajectory of tracers it was found that the air parcel was under the influence of the surface friction continuously until it leaves the boundary layer near the core. Then the air parcel with reduced amount of angular momentum compared to its original amount was transported from boundary layer to upper level of the vortex and contributed to form the anti-cyclone. These results suggest that the tropical cyclone loses angular momentum as it develops, which is due to the dissipation of angular momentum by the surface friction.

• Journal of the Korean Data and Information Science Society
• /
• 제28권4호
• /
• pp.819-829
• /
• 2017

가격의 추세가 형성되면 그 방향으로 진행하려는 price momentum 현상은 여러 국가의 거의 모든 주식, 채권 및 통화 시장에서 관찰되고 있다. KOSPI200선물을 대상으로 거래량 패턴과 일중 price momentum을 분석하였다. KOSPI200선물에서 장이 열릴 때와 닫힐 때 거래량이 집중되는 U자형 거래량 패턴이 관찰되었다. 9시 10분의 가격 수익률이 9시 시초가 대비 양 (+)이면 매수, 음 (-)이면 매도 진입하여 종가에 청산하는 전략의 유효성을 확인함으로써 일중 price momentum 현상이 존재함을 확인하였다. 또한, 9시부터 9시 10분까지 수익률이 점점 증가되는 J자형 가격 패턴 경우는 그렇지 않은 패턴 경우보다 price momentum 현상이 더 강함을 분석하였다. J자형 가격 패턴 여부를 판단하는 방법으로 DTW 분석 방식을 사용하였다. DTW 분석은 일중 가격 움직임을 예측하는데 유용함을 확인할 수 있었다.

• The Journal of Asian Finance, Economics and Business
• /
• 제8권7호
• /
• pp.365-373
• /
• 2021

This paper investigates the presence of momentum profits in the Saudi stock market. The study applied a quantitative method by utilizing monthly closing prices of 194 listed firms on Tadawal (Saudi Stock Market). The data from January 2010 to February 2019 is taken from the Tadawal market database for analysis. The sample is further divided into two equal sub-samples based on the structural changes that occurred in the Saudi stock market. Moreover, the high- and low-value traded portfolios are also constructed to examine the presence of momentum profits. Sixteen investment strategies are formed for each sample. The results show a very strong presence of momentum profits in the Saudi stock market for the full sample as well as for the sub-samples. The momentum profits are observed for a longer investment horizon. The results confirm that the short or medium-term formation of portfolios produces negative momentum returns for high-value traded stocks. The low-value traded stocks portfolios give similar results to the full sample results in terms of momentum profits. The results suggest that an investor should keep an eye on the past performance of desired stocks for at least three-nine months in which they are willing to invest.

• 한국과학교육학회지
• /
• 제21권5호
• /
• pp.841-854
• /
• 2001

The purpose of this study was to find the effect of these variables on the duration of the momentum effect. To examine the momentum effect for gravitational field concepts, an intensive time series design was used. We collected data every day except Sundays and holidays for 50 days; 5 days for baseline, 30 days for intervention, and 15 days for the follow up We adopted cognitive levels and styles as students characteristics and two item characteristics(quantity versus quality, and word versus picture) as the item representation patterns. In this study, the momentum effect was influenced by students characteristics and item representation patterns. The results showed that two variables, cognitive style and quantity/quality, were the most influential factors for the duration of momentum effect. Field independent students showed a longer duration than field dependent students did. In addition, students showed a longer duration in quality items than in quantity items. However, students cognitive levels(formal or preformal) and word/picture presentations seemed to have relatively weak effect on the duration of the momentum effect.