• 한국운동역학회지
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• 제30권3호
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• pp.247-253
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• 2020

Objective: This study aimed to examine the effects of real-time visual feedback gait training on gait stability in older adults. Method: Twelve older adults participated in this study, being divided into 2 groups including a) visual feedback (VF) and b) non-visual feedback (NVF) groups. For 4 weeks, VF performed a treadmill walking training with real-time visual feedback about their postural information while NVF performed a normal treadmill walking training. For evaluations of gait stability, kinematic data of 15-minute treadmill walking were collected from depth-based motion capture system (30 Hz, exbody, Korea). Given that step lengths in both right and left sides were determined based on kinematic data, three variables including step difference, coefficient of variation, approximate entropy were calculated to evaluate gait symmetry, variability and complexity, respectively. Results: For research findings, VF exhibited significant improvements in gait stability after 4-week training in comparison to NVF, particularly in gait symmetry and complexity measures. However, greater improvement in gait variability was observed in NVF than VF. Conclusion: Given that visual feedback walking gives potential effectiveness on gait stability in older adults, gait training with visual feedback may be a robust therapeutic intervention in people with gait disturbances like instability or falls.

• 한국운동역학회지
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• 제17권4호
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• pp.65-71
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• 2007

The purpose of this study was to investigate variability of kinematic factors affecting the record in women's javelin throwing. For this study, 8 female-javelin thrower participated in this experiment. The three digital video cameras (Sony, 120x) were used to record motions. Kwon3D 2.1 was used to process data and they were analyzed with Excell for factors. The sampling rate of a camera was 60Hz and shutter speed of a camera was 1/1000sec. The coordinate data were filtered using a fourth-order Butterworth low pass filtering with an estimated optimum cut-off frequency of 6Hz. The results were as follows: 1. From cross step to landing of delivery, the average velocities of CoM of non-dominant athletes were greater than dominant athletes and those of CoM of non-dominant athletes less than dominant athletes, but at release dominant athletes had a lower average velocity and a variability than non-dominant athletes. 2. From cross step to landing of delivery, the average throwing velocities and variabilities of a javelin of dominant athletes were greater than dominant athletes, but at release, dominant athletes had a higher velocity than dominant athletes and had a equal variability. 3. At every events, a forward or backward angles and variabilities of non-dominant athletes were greater than dominant athletes. 4. From cross step to landing of delivery, dominant athletes' elbow average angles were greater than non-dominant athletes and the variabilities of latter less than non-dominant athletes, but at release dominant athletes' variabilities were smaller than non-dominant athletes. 5. At landing of delivery, dominant athletes' knee average angles and variabilities of a supporting foot were a greater than non-dominant athletes, and at release, dominant athletes' knee average angles was a greater but variabilities less than non-dominant athletes. In conclusion, the dominant threw javelins fast while having stable postures and the range of elbow's angle large.

• 한국운동역학회지
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• 제18권2호
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• pp.49-58
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• 2008

본 연구의 목적은 트레드밀 보행 시, gait dynamics 측면에서 보행의 속도 변화와 인지과제 수행 시 보행 변인의 가변성(variability)을 알아보고자 하는 것이다. 실험은 인지과제의 동시수행 유/무에 따른 5가지 속도(선호속도의 80%, 90%, 100%, 110% and 120%)에 의한 보행 실험으로 구성되었다. 인지과제의 종류는 학습기능이 없는 인지과제(2-back task)를 수행하였다. 인지과제는 피험자의 트레드밀 보행 시, 3m 앞에 놓여진 스크린에 주어지고 무선마우스를 통해 응답하는 형태로 구성되었다. 실험의 모든 과정은 3차원 동작분석기를 통해 동작데이터를 획득하였다. 이를 통해, 5가지 보행 시간 변인과 3가지 공간 변인을 추출하였다. gait dynamics 측면의 분석을 위해, 가변성의 크기를 살펴볼 수 있는 방법인 분산계수(coefficient of variance)와 변동량의 구조적 자기 유사성을 추론할 수 있는 detrended fluctuation analysis (DFA)를 사용하였다. 그 결과 보행 속도 변화에 따라 보행 변인의 평균값과 분산계수에서 통계적 유의한 차이가 발생하였고, 인지과제의 수행 유/무에 따라서는 DFA에서 통계적인 차이가 발생하였다. 이는 인지과제의 수행에 의해 보행의 발생과 조절 능력에 영향을 끼쳤다고 추론할 수 있다. 본 연구 결과를 명백히 하기 위해 더 많은 수의 피험자 실험과 추가 실험이 필요할 것이다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.343-346
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• 2002

Toward more accurate determination of the water cycle in association with climate variability and change as well as baseline data on the impacts of this variability on water resources, the Coordinated Enhanced Observing Period (CEOP) was launched on July 1,2001. The preliminary data period, EOP-1, was implemented from July to September in 2001. The first annual enhanced observing period, EOP-3, is going to start on October 1,2002. CEOP is seeking to achieve a database of common measurements from both in situ and satellite remote sensing, model output, and four-dimensional data analyses (4DDA; including global and regional reanalyses) for a specified period. In this context a number of carefully selected reference stations are linked closely with the existing network of observing sites involved in the GEWEX Continental Scale Experiments, which are distributed across the world. The initial step of CEOP is to develop a pilot global hydro-climatological dataset with global consistency under the climate variability that can be used to help validate satellite hydrology products and evaluate, develop and eventually predict water and energy cycle processes in global and regional models. Based on the dataset, we will address the studies on the inter-comparison and inter-connectivity of the monsoon systems and regional water and energy budget, and a path to down-scaling from the global climate to local water resources, as the second step.

• Journal of the Korean Statistical Society
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• 제33권4호
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• pp.381-399
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• 2004

Statistical process control (SPC) and engineering process control (EPC) are based on different strategies for process quality improvement. SPC re-duces process variability by detecting and eliminating special causes of process variation, while EPC reduces process variability by adjusting compensatory variables to keep the quality variable close to target. Recently there has been need for an integrated process control (IPC) procedure which combines the two strategies. This paper considers a scheme that simultaneously applies SPC and EPC techniques to reduce the variation of a process. The process model under consideration is an IMA(1,1) model with a step shift. The EPC part of the scheme adjusts the process, while the SPC part of the scheme detects the occurrence of a special cause. For adjusting the process repeated adjustment is applied according to the predicted deviation from target. For detecting special causes the exponentially weighted moving average control chart is applied to the observed deviations. It was assumed that the adjustment under the presence of a special cause may increase the process variability or change the system gain. Reasonable choices of parameters for the IPC procedure are considered in the context of the mean squared deviation as well as the average run length.

• 한국운동역학회지
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• 제17권4호
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• pp.1-8
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• 2007

The purpose of this study was to investigate the difference in the stride-to-stride variability between two treadmill conditions; traditional treadmill and special treadmill whose speed can be adjusted automatically by subject's walking speed. Eight male subjects (25.1 years, 172.7 cm, 66.6 kg) were participated in treadmill walking experiment. First, preferred walking speed (PWS) of each subject was determined. Second, each subject performed walking experiment with fixed PWS condition and with free PWS condition for 10 minutes. 3D motion capture system (Motion analysis Corp., USA) with 6 cameras was used to collect motion data with sampling frequency of 120Hz. Temporal and spatial variables for stride-to-stride variability were calculated. Coefficient of variance (CV) which quantifies the amount of variability and Detrended Fluctuation Analysis (DFA) which explains the structure (self-similarity) of the variability were used for analysis. Results showed that the amount of variability during free PWS condition was greater than that of fixed PWS condition. DFA results showed that there was a statistical difference between two treadmill conditions for the variables of step length, stance time, and double support time. From these results, it is possible that traditional treadmill study might give incorrect conclusion about gait variability study. Further study is necessary to clarify these matters by considering the number of subjects, experimental time, and gait variables for the study of stride-to-stride variability.

• 한국정보과학회논문지:소프트웨어및응용
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• 제34권4호
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• pp.328-341
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• 2007

소프트웨어 프로덕트 라인을 구축하고자 할 때，첫 단계 활동은 도메인 분석을 통해 요구사항 들에서 가변성을 식별하는 것이고， 다음 단계는 일련의 관련된 프로덕트들의 전체적인 구조를 나타내는 도 메인 아키텍처를 개발하는 것이다 도메인 아키텍처는 소프트웨어 프로덕트 라인에 포함되어 있는 프로덕트들의 공통성과 가변성을 기술함으로써 프로덕트 라인의 핵심자산이 된다. 핵심자산의 가변성은 개발 프로세스가 진행됨에 따라 식별될 수 있는 가변 요소의 종류와 상세화 수준이 달라지기 때문에 아키텍처 수준에서 식별될 수 있는 가변성을 정의하고 이를 체계적으로 식별하여 아키텍처 모델에 명시적으로 표현하는 것이 중요하다. 아키텍처 수준에서 고려해야 하는 가변성은 아키텍처 구성 요소들에서 발생하는 가변성 뿐만 아니라 이들의 구성(configuration) 관계를 나타내는 모텔에서 나타나는 가변성들까지 고려해야 하기 때문에， 이들 사이의 복잡한 관계를 이해하고 표현하는 것은 매우 힘든 일이며 이에 대한 기존 연구가 부족한 실정이다. 본 논문에서는 공통성과 가변성이 명시적으로 고려되는 프로덕트 라인의 핵심 자산으로서 도메인 아키텍처를 개발하는 방법을 제시한다. 이를 위해， 최근 Object Management Group(OMG)에서 채택한 재사용 자산 병세(Reusable Asset Specification; RAS) 모델을 확장하여 공통성과 가변성 개념이 명확히 정의된 도메인 아키텍처 메타모델을 제시한다. 제시되는 메타모델에는 아키텍처의 구성요소들이 정의되어 있으며， 각 구성요소와 모텔에서 식별 될 수 있는 가변성이 상세화 수준에 따라 두 가지 형태로 구분되어 제시되어 있다. 또한 본 메타모델을 기반으로 특정 도메인에 대한 아키텍처에 가변성이 명시적으로 표현되는 방법을 보인다.

• Asian-Australasian Journal of Animal Sciences
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• 제22권1호
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• pp.1-6
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• 2009

Genetic variability is an important component in the ability of populations to adapt in the face of environmental change. Severe human impacts reduced Muzzafarnagri sheep of India from 500,000 in 1972 to 10,989 in 1973-74. Here we report for the first time the effect of this population decline on levels of genetic variability at 13 FAO recommended ovine microsatellite loci and contrast levels of variability to that in a breed from the same geographical region, which differed in numbers, by an order of magnitude (Marwari sheep). Of the 13 loci, 100% were polymorphic in both breeds. A high degree of genetic variation was observed within populations in terms of both allele diversity (number of alleles per locus, >4) and gene diversity (expected heterozygosity, >0.5), which implied that there is still a substantial amount of genetic diversity at the nuclear loci in a declining population. Nevertheless, overall low number of alleles per locus and relatively less abundance of low frequency alleles in Muzzafarnagri sheep suggested that genetic variability has been comparatively reduced in this population. Bottleneck analysis indicated that a genetic bottleneck did not occur during the most recent decline. In addition, we found that the differentiation among populations was moderate ($F_{ST}$= 11.8%). This study on assessment of genetic effects of the population declines in ovines is a step towards identification of genetically impoverished or healthy populations, which could prove to be a useful tool to facilitate conservation planning in this important species of small ruminants.

• Steel and Composite Structures
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• 제4권5호
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• pp.385-402
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• 2004

Nearly 400 composite railway bridge decks of a new kind belonging to the trough type with U-shaped cross section have been constructed in Belgium over the last fifteen years. The construction of these bridge decks is rather complex with the preflexion of precambered steel girders, the prestressing of a concrete slab and the addition of a 2nd phase concrete. Until now, they have been designed with a classical computation method using a pseudo-elastic analysis with modular ratios. Globally, they perform according to the expectations but variability has been observed between the measured and the computed camber of these bridge decks just after the transfer of prestressing and also at long-term. A statistical analysis of the variability of the relative difference between the measured camber and the computed camber is made for a sample of 36 bridge decks using no less than 10 variables. The most significant variables to explain this variability at prestressing are the ratio between the maximum tensile stress reached in the steel girders during the preflexion and the yield strength and the type of steel girder. For the same sample, the long-term camber under permanent loading is computed by two methods and compared with measurements taken one or two years after the construction. The camber computed by the step-by-step method shows a better agreement with the measured camber than the camber computed by the classical method. The purpose of the paper is to report on the statistical analysis which was used to determine the most significant parameters to consider in the modeling in order to improve the prediction of the behaviour of these composite railway bridge decks.

• Journal of information and communication convergence engineering
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• 제8권2호
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• pp.201-204
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• 2010

In the mobile healthcare system, a very important vital sign in analyzing the status of user health is the HRV (heart rate variability). The used signals for measuring the HRV are electrocardiograph and PPG (photoplethysmograph). In extracting the HRV from the PPG signal, an important issue is that extract the exactly HRV from PPG signal distorted from the user's movements. This study suggested a design method of the Kalman filter to solve the problem, and evaluated the performances of a proposed method by PPG signals containing motion artifacts. In the results of experiments that compared with a variable step size adaptive filter proposed in recently, the proposed method showed better performance than an adaptive filter.