• 가족자원경영과 정책
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• 제17권1호
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• pp.241-263
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• 2013

Time pressure and financial burden have been reported as the main constraints on leisure participation. The purpose of this study was to explore a typology of leisure constraints, investigate the characteristics of leisure constraint types, and analyze the differences in leisure participation by the types of leisure constraints for married employees. The data source for this research was the 2009 Time Use Survey conducted by the Korea National Statistical Office (KNSO). Married employees aged 20 to 59 years completed 13,476 time diaries (7,984 for male, 5,492 for female), which were analyzed using chi-square, cluster analysis, and ANOVA analysis. Leisure constraints were classified into five types in two categories, working time per week and personal income for both males and females respectively. The three types for both males and females were time-income constraints, income constraints, and general constraints, with an additional type for men, $time^+$-income constraints, and an additional type for women, time constraint. The most common type was general constraints, for both males and females. Each type was further differentiated by the following socio-economic variables: age, educational level, job type, and weekly day-off. The study found that participation in study, sports, and religious activities varied with the types of leisure constraints.

• 한국통신학회논문지
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• 제29권12A호
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• pp.1333-1339
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• 2004

IS-95와 IMT-2000 시스템에서 사용되고 있는 여러 종류의 길쌈 부호기를 부호율 1/2, 구속장 3인 길쌈 부호기로 한정하여, neural network의 LVQ(Learning Vector Quantization)과 PVSL(Prototype Vector Selecting Logic)을 적용하여 비터비 복호기에서 사용되는 PM(Path Metric)과 BM(Branch Metric) 메모리 수와 산술$.$비교 연산량을 줄임으로써 시스템의 단순화와 순방향 복호를 가능하게 한다. 구속장의 확장성 여부와 관계없이 간단한 응용으로 기존의비터비 복호기에 적용할 수 있는 새로운 비터비 복호기의 구조와 적용 알고리즘을 제시하고, 제시된 비터비 복호기의 합리성을 VHDL 시뮬레이션으로 검증 후, 기존의 복호기와의 성능을 비교 분석한다.

• 대한기계학회논문집A
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• 제33권4호
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• pp.409-416
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• 2009

Standard procedures for a fracture toughness testing require very severe restrictions for the specimen geometry to eliminate a size effect on the measured properties. Therefore, the used standard fracture toughness data results in the integrity assessment being irrationally conservative. However, a realistic fracture in general structures, such as in nuclear power plants, may develop under the low constraint condition of a large scale yielding with a shallow surface crack. In this paper, cleavage fracture toughness tests have been made on side-grooved PCVN (precracked charpy V-notch) type specimens (10 by 10 by 55 mm) with various crack depths. The constraint effects on the crack depth ratios were evaluated quantitatively by the developed scaling method using the 3-D finite element method. After the fracture toughness correction from scaling model, the statistical size effects were also corrected according to the standard ASTM E 1921 procedure. The results were evaluated through a comparison with the $T_0$ of the standard CT specimen. The corrected $T_0$ for all of the PCVN specimens showed a good agreement to within $5.4^{\circ}C$ regardless of the crack depth, while the averaged PCVN $T_0$ was $13.4^{\circ}C$ higher than the real CT test results.

• 대한기계학회논문집A
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• 제29권8호
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• pp.1123-1131
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• 2005

In this paper, a formulation for a spatial sliding joint, which a general multibody can move along a very flexible cable, is derived using absolute nodal coordinates and non-generalized coordinate. The large deformable motion of a spatial cable is presented using absolute nodal coordinate formulation, which is based on the finite element procedures and the general continuum mechanics theory to represent the elastic forces. And the non-generalized coordinate, which is neither related to the inertia forces nor external forces, is used to describe an arbitrary position along the centerline of a very flexible cable. In the constraint equation for the sliding joint, since three constraint equations are imposed and one non-generalized coordinate is introduced, one constraint equation is systematically eliminated. Therefore, there are two independent Lagrange multipliers in the final system equations of motion associated with the sliding joint. The development of this sliding joint is important to analyze many mechanical systems such as pulley systems and pantograph/catenary systems for high speed-trains.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.920-925
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• 2001

A study on the topology optimization of a multi-spectral camera for space-use is presented. A multi-spectral camera for space-use experiences degradation of optical image in the space, which can not be detected on the optical test bench on the earth. An optical surface deformation of a primary mirror, which is a principal component of the camera system, under the self-weight loading is an important factor affecting the optical performance of the whole camera system. In this study, topology optimization of the primary mirror of the camera is presented. Total mass of the primary mirror is given as a constraint to the optimization problem. The sensitivities of the objective function and constraint are calculated by direct differentiation method. Optimization procedure is carried out by an optimality criterion method using the sensitivities of the objective function and the constraint. As a preliminary example, topology optimization considering a self-weight loading is treated. For practical use, the polishing pressure is included as a loading in the topology optimization of the primary mirror. Results of the optimized design topology for the primary mirror with varying mass ratios are presented.

• 대한조선학회논문집
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• 제41권5호
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• pp.55-62
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• 2004

The logistics of entire shipbuilding process are integrated during the block erection process and the schedules for the erection process are made prior to. the schedules of any other processes. Therefore, efficient scheduling of the block erection process are one of most important issues in shipbuilding. There are only a few studies published regarding block erection scheduling methods because of its complexity and variability. This paper proposes an algorithm for diminution of maximum load based on constraint satisfaction technique. it is developed primarily for the efficiency in load leveling and applicability to the actual block erection process. The proposed algorithm is applied to actual block erection process and the results shows improvements in load leveling. It can also be used for the scheduling of fabrication, sub-assembly, and assembly to improve load leveling.

• 한국전문물리치료학회지
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• 제19권2호
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• pp.59-68
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• 2012

This meta-analysis investigated the effects on arm motor impairment, arm motor function and disability, and psychological aspects of constraint-induced movement therapy (CIMT) for upper extremity hemiparesis following stroke, based on Korean studies. A comprehensive search of the complete Korean studies information service system (KISS), Research Information Sharing Service (RISS), Korea National Library, and the Korean Medical Database to September 2011 was conducted. Eleven eligible controlled clinical trials compared CIMT to a control group or an alternative treatment. All outcome measures of arm motor impairment, arm motor function and disability, and psychological aspects were pooled for calculating effect size. The overall effect size of CIMT was .700 (95% confidence interval=.482~.918). The CIMT programs showed large effect on the aspect of arm motor function and disability (the effect size is .920) and the psychological aspect (the effect size is .946). The effect of CIMT on arm motor impairment was moderate (the effect size is .588). These results show that CIMT may improve upper extremity motor impairment, function and disability, and psychological aspects following stroke. However, these results were based on a small number of studies, and not all of them were randomized control trials. Additional research is needed to include larger well-designed trials to resolve these uncertainties.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.244-246
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• 1998

Robust control for DC motor is needed according to the highest precision of industrial automation. However when a motor control system with PID controller has an effect of load disturbance, it is very difficult to guarantee the robustness of control system. As a compensation method solving this problem, in this paper, PID-supervision hybrid control method for motor control system is presented. If the PID control system (without the supervisory controller) is stable in the sense that the error is inside the constraint set, the supervisory control is idle. If the error hits the boundary of the constraint, the supervisory controller begins operation to force the error back to the constraint set. We prove that the PID-supervision hybrid control system is globally stable in the sense that the error is guaranteed to be within the tolerance limits specified by the system designer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.843-845
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• 1995

There are a variety of trajectory and control algorithms available for robot trajectory tracking. Before using the enhanced trajectory and control algorithms to reduce the tracking error, we introduce the new method which reduces the tracking error by clipping the joint velocity. A lot of robot trajectory tracking methods are proposed to enhance the robot tracking, but irregular tracking errors are always accompanied. Up to now, these irregular tracking errors are gradually but uniformly reduced by introducing more complicated control algorithms. It is intuitively obvious to reduce only the big errors selectively in the irregular ones for the better performance. By heuristic method, big tracking errors in these irregular ones are assumed mostly due to the fast moving of joint with respect to the same tracking and control method. So, in this paper, we introduce a new method which reduce the big tracking errors by clippings the joint velocity with the constraint of given path. Using this method, desired trajectory tracking is obtained within the far reduced error bound. Also, this method is successfully applied to generate the path-constrained error reducing trajectories for 2-axis SCARA type robot.

• 한국정보처리학회논문지
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• 제6권2호
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• pp.439-448
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• 1999

본 논문에서는 신경회로망과 유전자 알고리즘을 이용하여 셀룰러 무선채널 할당을 위한 최적화 알고리즘을 제안하였다. 채널할당 과정을 채널할당 문제에 내포된 제한사항들을 나타내는 에너지함수의 최소화 과정으로 규정하였다. 채널간, 인접채널, 사이트간의 세 가지 제한사항이 고려되었다. 최적의 채널할당을 위하여 신경회로망을 이용한 방식에서는 강제적인 채널 할당 및 셀 순서 변화 등의 기법이 개발되었고 유전자 알고리즘 방식에서는 자료구조와 적절한 유전연산자를 개발하였다. 실험결과로서, 두 최적화 방법의 채널할당률을 나타내었고 그 결과들을 비교하였다.