• 한국건축시공학회지
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• 제5권1호
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• pp.53-61
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• 2005

The purpose of this study presents useful data on the choice or development of floor covering from slip viewpoint by examining closely the impact of the changes in sliding experiments due to the wear of floor covering by walk. The result of wear practical test per ten thousand walks enforces some kind of popular floor covering and measure of coefficient of slip resistance as follows: (1) When surface of floor covering is in the state of wet, the degree of wear doesn't affect greatly in slip. (2) When surface of floor covering is in dry and clean state, most floor coverings have the tendency to lower the coefficient of slip resistance with the amount of walk on it. (3) Change in the tendency of slip resistance by wear appeared mainly due to the differences in the state of floor covering and organic floor covering appeared to have great reduction of coefficient of slip resistance than the inorganic ones. (4) According to the result of investigation on changes in tendency of coefficient of slip resistance due to the increase in the number of walk and if two hundred thousand walks were done, regardless of surface shape or kind of site, etc, the safety of floor covering, in slip viewpoint, greatly reduces.

• 한국통신학회논문지
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• 제19권11호
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• pp.2160-2169
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• 1994

동기식통신망의 클럭들에서 발생되는 위상시간에러(phase time error)의 성분은 주로 플리커잡음(flicker noise)및 랜덤워크잡음(random-walk noise)이다. 본 논문에서는 먼저 주파수 안정도에 대한 측정표준을 설명하였다. 그리고 백색잡음으로부터 플리커잡음 및 랜덤워크잡음을 디지털 컴퓨터상에서 생성시킬 수 있는 알고리즘을 소개하였는데, 특히 플리커잡음에 대해서는 단수(stage number) N, 시정수비(time constant ratio) K와 플리커잡음생성대역폭의 관계를 예를 들어 규명하였다. 동기식망에서 발생되는 위상시간에러를 실제 측정한 결과에 따라서 이 알고리즘을 이용하여 컴퓨터로 클럭의 위상시간에러를 시뮬레이션하였다.

• 대한산업공학회지
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• 제29권2호
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• pp.135-144
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• 2003

Traffic performance in a microcellular system is much more affected by cell dwell time and channel holding time in each cell. Cell dwell time of a call is characterized by its mobility pattern, i.e., stochastic changes of moving speed and direction. Cell dwell time provides important information for other analyses on traffic performance such as channel holding time, handover rate, and the average number of handovers per call. In the next generation mobile communication system, the cell size is expected to be much smaller than that of current one to accommodate the increase of user demand and to achieve high bandwidth utilization. As the cell size gets small, traffic performance is much more affected by variable mobility of users, especially by that of pedestrians. In previous work, analytical models are based on simple probability models. They provide sufficient accuracy in a simple second-generation cellular system. However, the role of them is becoming invalid in a picocellular environment where there are rapid change of network traffic conditions and highly random mobility of pedestrians. Unlike in previous work, we propose an improved probability model evolved from so-called Random walk model in order to mathematically formulate variable mobility of pedestrians and analyze the traffic performance. With our model, we can figure out variable characteristics of pedestrian mobility with stochastic correlation. The above-mentioned traffic performance measures are analyzed using our model.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1500-1503
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• 2003

One of the main goals in the rehabilitation of SCI patients is to enable the patient to stand and walk themselves. We are developing high-thrust powered gait orthosis(PGO) that use air muscle actuator(shadow robot Co., UK) to be assisted gait and rehabilitation purposes of them. We made of PD controller and measured hip joint angle by its load and the pressure to control air muscle of PGO. As a results, maximum flexion angle of hip joint is $20^{\circ}$, and angular velocity is 30.4${\pm}2.5^{\circ}/sec$, and then delay time of system was average 0.62${\pm}$0.03s. As the hip flexion angle and the pelvic angle is decreased during the gait with PGO, the patient can walk faster. By using the PGO, the energy consumption can also be decreased. therefore, the proposed PGO can be a very useful assitive device for the paraplegics to walk.

• 한국전문물리치료학회지
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• 제18권3호
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• pp.16-25
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• 2011

This study aimed to evaluate factors related to the ability of ambulatory patients with cerebral palsy (CP) to walk over vertical and horizontal obstacles. Twenty patients with spastic CP who were able to walk independently for at least 10 m with or without walking devices were recruited for the study. Participants were required to walk over small obstacles (1, 4, and 8 cm in height or width; total of 6 conditions). A 'fail' was recorded when either the lower limbs or the walking device contacted the obstacle. Linear regression analyses were used to determine the effects of age, sex, walking devices, eyeglasses, subtype (hemiplegia or diplegia), ankle foot orthoses, functional level, and score of body mass index on the ability of obstacle crossing. Fifteen participants (75%) failed to adequately clear the foot or walking device over obstacles in at least 1 condition. The chance of failure in crossing vertical obstacle was affected by the use of ankle foot orthoses, eyeglasses, gender, and CP subtype (p<.05). The failure rate crossing horizontal obstacle was affected by CP subtype. These findings suggest that rehabilitation procedures should (1) consider the clinical characteristics of patients in order to prepare them to be more independent while performing daily activities, and (2) incorporate environmental conditions that patients encounter at home and in the community.

• 인터넷정보학회논문지
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• 제4권6호
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• pp.43-55
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• 2003

워크플로우 마이닝이란 워크플로우 관리시스템에서 생성되고 실행되어진 비즈니스 프로세스의 인스턴스의 실행경로를 분석하여 새로운 정보론 추출하는 과정을 의미한다. 본 논문에서는 빌드타임(Build Time)에 정의된 모델의 실행경로와 런타임(Run Time)에서 실행된 워크케이스의 실행경로를 비교/분석하여 새로운 워크플로우 모델의 제시 또는 작성된 비즈니스 프로세스의 개선을 위한 작업으로서 액티비티(activi쇼) 의존성을 이용한 워크케이스 마이닝에 관하여 기술하겠다. 제안된 워크케이스 마이닝을 위하여 각 액티비티의 의존성을 분석하여 중요경로(Essential Path)를 결정하는 액티비티 의존 넷 알고리즘(Activity-Dependent Net Algorithm)과 워크케이스 실행 정보를 이용하여 중요 경로와 일치여부를 결정하는 실행계열 분석 알고리즘(E-Walk Series Analysis Algorithm)을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권7호
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• pp.2568-2584
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• 2015

Spectral clustering has become one of the most popular clustering approaches in recent years. Similarity graph constructed on the data is one of the key factors that influence the performance of spectral clustering. However, the similarity graphs constructed by existing methods usually contain some unreliable edges. To construct reliable similarity graph for spectral clustering, an efficient method based on Markov random walk (MRW) is proposed in this paper. In the proposed method, theMRW model is defined on the raw k-NN graph and the neighbors of each sample are determined by the probability of the MRW. Since the high order transition probabilities carry complex relationships among data, the neighbors in the graph determined by our proposed method are more reliable than those of the existing methods. Experiments are performed on the synthetic and real-world datasets for performance evaluation and comparison. The results show that the graph obtained by our proposed method reflects the structure of the data better than those of the state-of-the-art methods and can effectively improve the performance of spectral clustering.

• Wind and Structures
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• 제11권4호
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• pp.303-321
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• 2008

When first commissioned, the 1.6 km span 275kV Severn Crossing Conductor experienced large amplitude vibrations in certain wind conditions, but without ice or rain, leading to flashover between the conductor phases. Wind tunnel tests undertaken at the time identified a major factor was the lift generated in the critical Reynolds number range in skew winds. Despite this insight, and although a practical solution was found by wrapping the cable to change the aerodynamic profile, there remained some uncertainty as to the detailed excitation mechanism. Recent work to address the problem of dry inclined cable galloping on cable-stayed bridges has led to a generalised quasi-steady galloping formulation, including effects of the 3D geometry and changes in the static force coefficients in the critical Reynolds number range. This generalised formulation has been applied to the case of the Severn Crossing Conductor, using data of the static drag and lift coefficients on a section of the stranded cable, from the original wind tunnel tests. Time history analysis has then been used to calculate the amplitudes of steady state vibrations for comparison with the full scale observations. Good agreement has been obtained between the analysis and the site observations, giving increased confidence in the applicability of the generalised galloping formulation and providing insight into the mechanism of galloping of yawed and stranded cables. Application to other cable geometries is also discussed.

• 대한교통학회지
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• 제21권6호
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• pp.43-55
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• 2003

본 연구에서 대중교통 수요예측과정에서 교통죤(TAZ)내의 거주인구, 직장인 등 대중교통이용가능 잠재수요 추정을 개선하기 위한 새로운 방법이 제시되었다. 대중교통을 이용하기 위해서는 보행 또는 승용차(Park & Ride or Kiss & Ride)로 대중교통에 접근하는 바, 제시된 방법이 보행에 의한 대중교통 잠재수요 및 승용차에 의한 대중교통 잠재수요를 추정하는 데 있어 기존의 buffer method 및 network ratio method보다 합리적이고 개선된 방법임을 보여주고 있다. 본 연구에서 제시된 방법은 교통수단선택모형(mode choice model)의 적용과정에서 대중교통 수요예측을 개선할 수 있을 것으로 기대된다.

• Journal of the Korean Data and Information Science Society
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• 제25권2호
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• pp.385-392
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• 2014

랜덤워크 가설은 금융시장의 예측 어려움을 이론적으로 설명하는 가설이다. 현재까지 다양한 랜덤워크 검정방법들이 개발되어 왔으나 낮은 검정력과 유의수준 왜곡 등의 문제를 보이는 것으로 알려져 있다. 본 논문에서는 이러한 문제점들을 개선하기 위해 부호검정에 기초한 랜덤워크 검정방법을 제안하였다. 랜덤워크와 관련하여 흔히 사용되고 있는 Dickey와 Fuller (1979) 검정과 모의실험을 통해 성능을 비교하였다.