• Journal of Astronomy and Space Sciences
• /
• 제26권3호
• /
• pp.287-294
• /
• 2009

In helioseismology it is normally assumed that p-mode oscillations are excited in a statistically independent fashion. Unfortunately, however, this issue is not clearly settled down in that two experiments exist, which apparently look in discrepancy. That is, Appourchaux et al. (2000) looked at bin-to-bin correlation and found no evidence that the assumption is invalid. On the other hand, Roth (2001) reported that p-mode pairs with nearby frequencies tend to be anti-correlated, possibly by a mode-coupling effect. This work is motivated by an idea that one may test if there exists an excess of anticorrelated power variations of pairs of solar p-modes. We have analyzed a 72-day MDI spherical-harmonic time series to examine temporal variations of p-mode power and their correlation. The power variation is computed by a running-window method after the previous study by Roth (2001), and then distribution function of power correlation between mode pairs is produced. We have confirmed Roth's result that there is an excess of anti-correlated p-mode pairs with nearby frequencies. On the other hand, the amount of excess was somewhat smaller than the previous study. Moreover, the distribution function does not exhibit significant change when we paired modes with non-nearby frequencies, implying that the excess is not due to mode coupling. We conclude that the origin of this excess of anticorrelations may not be a solar physical process, by pointing out the possibility of statistical bias playing the central role in producing the excess.

• Journal of Veterinary Science
• /
• 제21권3호
• /
• pp.21.1-21.14
• /
• 2020

Background: Physical exercise is known to cause significant joint changes. Thus, monitoring joint behavior of athletic horses is essential in early disorders recognition, allowing the proper management. Objectives: The aims of this study were to determine the morphological patterns, physical examination characteristics and ultrasound findings of show jumping horses in training and to establish a score-based examination model for physical and ultrasound follow-ups of metacarpophalangeal joint changes in these animals. Methods: A total of 52 metacarpophalangeal joints from 26 horses who were initially in the taming stage were evaluated, and the horses' athletic progression was monitored. The horses were evaluated by a physical examination and by B-mode and Doppler-mode ultrasound examinations, starting at time zero (T0), which occurred concomitantly with the beginning of training, and every 3 months thereafter for a follow-up period of 18 months. Results: The standardized examination model revealed an increase in the maximum joint flexion angles and higher scores on the physical and ultrasound examinations after scoring was performed by predefined assessment tools, especially between 3 and 6 months of evaluation, which was immediately after the horses started more intense training. The lameness score and the ultrasound examination score were slightly higher at the end of the study. Conclusions: The observed results were probably caused by the implementation of a training regimen and joint adaptation to physical conditioning. The joints most likely undergo a pre-osteoarthritic period due to work overload, which can manifest in a consistent or adaptive manner, as observed during this study. Thus, continuous monitoring of young athlete horses by physical and ultrasound examinations that can be scored is essential.

• 한국항행학회논문지
• /
• 제17권2호
• /
• pp.196-201
• /
• 2013

본 논문은 대칭 구조의 CRLH 전송선로를 바탕으로 이중모드에서 동작하는 평형 필터 설계를 제안한 것이다. 기존의 대칭 구조와는 다르게 이 구조에서는 공통 모드와 차동 모드의 이중모드에서 동작한다. 이러한 성질은 이 구조의 대칭면에 단락회로를 그라운드 비아에 의해서 동작되도록 구현하였다. 이렇게 하면 공통 모드와 차동 모드에서 모두 동작하는 특성을 얻을 수 있으며, 이러한 성질을 이용하여 평형 필터를 구현하였다. 이러한 특징들을 확인하기 위하여 5개의 대칭 CRLH 단위 셀로 시뮬레이션, 제작 및 측정을 하여 공통 모드와 차동 모드에서 동일하게 동작하는 평형 필터의 특성을 얻었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 춘계학술대회 논문집 디스플레이 광소자 분야
• /
• pp.100-103
• /
• 2005

Homogeneously aligned nematic liquid crystal modes are representatively the -FFS (fringe-field switching) mode using liquid crystal (-LC) with negative dielectric anisotropy, the +FFS mode and the IPS (in-plane switching) mode using +LC with positive dielectric anisotropy. In view of image quality evaluation standard of LCD, we compared characteristics of the brightness, the contrast ratio (CR) and color shift when the modes have respectively optimized phase retardation values $(d{\Delta}n)$. Consequently, in the most sensitively viewing angle of a man's physical vision, both FFS modes have advantage over the IPS mode from the brightness & the CR point of view. We are also confirmed that the +FFS mode out of them shows the smallest color shift according to all viewing directions in grey levels.

• International Journal of Advanced Culture Technology
• /
• 제11권2호
• /
• pp.330-344
• /
• 2023

This research report cuts across management sciences (market strategy entry mode development) and innovative technology (Electric Vehicle (EV)) alongside measures to submerge global warming. The development of a successful entry mode for the electric Vehicle into the African continent is the main objective of the study. The study focuses on an analysis of how electric car manufacturers can enter the African market in other to achieve global sustainability and social responsibility. The methodology is based on identifying the factors that affect the choice of an entry mode into international markets by multinational companies desiring to leverage their revenue through a foreign market. It also offered a quantitative approach that can support the economic and sustainability entry mode model for EVs and a qualitative approach of Porter's five forces analysis as an entry mode coaching tool for EVs. These proxies are used in quite a wide range of multivariate statistical methods (trend analysis, ratio, and probability, comparative t-test technique, auto-regression, and ordinary least square technique). The result acknowledges joint venture and setting of the plant (physical presents) as the optimal entry mode in African EV market. It requires the EV manufacturers a tire-free emission innovation technology in order to optimize the global sustainability initiative.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2005년도 춘계 학술발표회 논문집
• /
• pp.409-416
• /
• 2005

Design analysis for underground spaces requires evaluating stability related to tunnel collapses. A failure mode is one of the critical factors in the conventional methods of stability analysis. Therefore identification of failure modes is essential in securing safe construction in the phase of design analysis, instrumentation planning and implementation of reinforcing measures. In this study failure modes at the tunnel heading in granular soils are investigated using physical model tests and numerical simulation for various tunnel depths and ground surface inclinations. Test results indicated that the effect of depth and inclination of ground surface on a failure mode are significant. It is identified that, with an incase in depth, failure modes become localized in a region close to the tunnel. It is also known that an increase in the inclination of ground surface results in inclined and wide failure modes.

• Earthquakes and Structures
• /
• 제8권4호
• /
• pp.843-857
• /
• 2015

System identification is regarded as the most basic technique for structural health monitoring to evaluate structural integrity. Although many system identification techniques extracting mode information (e.g., mode frequency and mode shape) have been proposed so far, it is also desired to identify physical parameters (e.g., stiffness and damping). As for high-rise buildings subjected to long-period ground motions, system identification for evaluating only the shear stiffness based on a shear model does not seem to be an appropriate solution to the system identification problem due to the influence of overall bending response. In this paper, a system identification algorithm using a shear-bending model developed in the previous paper is revised to identify both shear and bending stiffnesses. In this algorithm, an ARX (Auto-Regressive eXogenous) model corresponding to the transfer function for interstory accelerations is applied for identifying physical parameters. For the experimental verification of the proposed system identification framework, vibration tests for a 3-story steel mini-structure are conducted. The test structure is specifically designed to measure horizontal accelerations including both shear and bending responses. In order to obtain reliable results, system identification theories for two different inputs are investigated; (a) base input motion by a modal shaker, (b) unknown forced input on the top floor.

• Geomechanics and Engineering
• /
• 제17권4호
• /
• pp.323-331
• /
• 2019

The presence of defects in nature changes the physical parameters of the rock. In this paper, by studying the rock-like specimens with conjugated fractures, the horizontal angle and length are changed, and the physical parameters and failure modes of the specimens under uniaxial compression test are analyzed and compared with the results of simulation analysis. The experimental results show that the peak strength and failure mode of the rock-like specimens are closely related to the horizontal angle. When the horizontal angle is $45^{\circ}$, the maximum value is reached and the tensile failure mode is obtained. The fracture length affects the germination and propagation path of the cracks. It is of great significance to study the failure modes and mechanical properties of conjugated fracture rock-like specimens to guide the support of fractured rock on site.

• Nuclear Engineering and Technology
• /
• 제55권8호
• /
• pp.2905-2918
• /
• 2023

The valve assembly used in nuclear power plants is important safety-related equipment. In the new standard, the physical attributes are measured using a valve diagnosis test, which is used in the expansion to other non-tested valves using a quantitative test-basis methodology. With a motor-operated actuator, the state of stem's lubrication is related to physical attributes such as the stem factor and the friction coefficient. This study analyzed the numerical transient of fluid and solid lubrication with a squeeze film effect due to the loading rate on the stem and the stem nut using the experimental data. The differential equation that governs the motion mechanism of the stem and stem nut is established and analyzed. The flow rate, the fluid and the solid contact forces are calculated with the friction coefficient. Finally, we found that a change in the friction coefficient results from a change of the shear force in the solid contact mode during the interchange process between the solid contact mode and the fluid contact mode. The qualitative understanding of the squeeze film effect is expanded quantitatively for forces, thread surface distance, velocity, and acceleration, with consideration of the metal solid contact and fluid contact.

• 한국정보과학회논문지:시스템및이론
• /
• 제35권6호
• /
• pp.293-303
• /
• 2008

컴퓨팅 환경이 무선과 휴대용 시스템으로 변화하면서, 전력효율이 점점 중요해지고 있다. 특히 내장형 시스템일 경우에 더욱 그러한데 이중 메모리에서 소모되는 전력이 전체 전력소모의 두 번째 큰 요소가 되고 있다. 메모리 시스템에서의 전력소모를 줄이기 위해서 SDRAM의 저전력 모드를 활용할 수 있다. RDRAM의 경우 냅모드(nap mode)는 액티브 모드(active mode)의 5%이하의 전력만을 소모한다. 하지만 하드웨어 컨트롤러는 운영체제가 협조하지 않으면 이 기능을 효율적으로 활용하지 못한다. 이 논문에서는 SDRAM의 액티브 유닛(active unit)의 수를 최소화하는 방법에 초점을 맞춘다. 운영체제는 참조되지 않는 메모리를 저전력 모드에 놓음으로써 최소한의 유닛들만을 액티브 모드에 놓은 상태로 프로그램이 수행될 수 있도록 피지컬(physical) 페이지들을 할당한다. 이것은 PAVM(Power Aware Virtual Memory) 연구의 일반화된 시스템 전반에 대한 연구라고 할 수 있다. 우리는 모든 피지컬 메모리를 고려하고 있으며, 특히 평균적으로 전체 메모리의 절반을 사용하는 버퍼 캐시를 고려하고 있다. 버퍼 캐시의 용량과 그 중요성 때문에 PAVM 방식은 버퍼 캐시를 고려하지 않고는 완전한 해법이 되지 못한다. 이 논문에서 우리는 메모리의 사용처를 분석하고 저전력 페이지 할당 정책을 제안한다. 특히 프로세스의 주소공간에 매핑(mapping)된 페이지들과 버퍼 캐시가 고려된다. 이 두 종류의 페이지들간의 상호작용과 그 관계를 분석하고 저전력을 위해 이러한 관계를 이용한다.