• 대한기계학회논문집B
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• 제27권5호
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• pp.628-634
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• 2003

We present numerical and experimental results of periodic flows inside a rectangular container under a background rotation. The periodic flows are generated by changing the speed of rotation periodically so that a time-periodic body forces produce the unsteady flows. In numerical computation, a parallel-computation technique with MPI is implemented. Flow visualization and PIV measurement are also performed to obtain velocity fields at the free surface. Through a series of numerical and experimental works, we aim to clarify, if any, the fundamental reasons \ulcornerf discrepancy between the two-dimensional computation and the experimental measurement, which was detected in the previous study for the same flow model. Specifically, we check if the various assumptions prerequisite for the validity of the classical Ekman pumping law are satisfied for periodic flows under a background rotation.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.671-680
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• 2004

We present numerical and experimental results of the periodic flows inside a rectangular container under a background rotation. In numerical computation, a parallel-computation technique with MPI is implemented. Flow visualization and PIV measurement are also performed to obtain velocity fields at the free surface. Through a series of numerical and experimental works, we aim to clarify the fundamental reasons of discrepancy between the two-dimensional computation and the experimental measurement, which was detected in the previous study for the same flow model. Specifically, we check if the various assumptions prerequisite for the validity of the classical Ekman pumping law are satisfied for periodic flows under a background rotation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.325-328
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• 2002

We present numerical and experimental result of the rotating flows inside a rectangular container under a background rotation. In numerical computation, a parallel-computation technique with MPI is implemented. Flow visualization and PIV measurement are also performed to obtain velocity fields at the free surface. Through a series of numerical and experimental works, we aim to clarify, if any, the fundamental reasons of discrepancy between the two-dimensional computation and the experimental measurement, which was detected in the previous study for the same flow model. Specifically, we check if the various assumptions prerequisite for the validity of the classical Ekman pumping law are satisfied for periodic flows under a background rotation.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 춘계학술대회 논문집
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• pp.215-219
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• 2002

In this study, we show the numerical and the experimental results for fluid motions inside a rectangular container subjected to a background rotation added by a rotational oscillation. In the numerical computation, we used a parallel computer system of PC-cluster type. Attention is given to dependence of the flow patterns on the parameter change. It shows that the flow becomes in a periodic state at low Reynolds numbers and undergoes a transition to a chaotic motion at high Reynolds numbers. It also shows that the fluid motion tends to be depth-independent at ${\epsilon}$ up to 0.3 for Re lower than 5235.

• 대한기계학회논문집B
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• 제24권6호
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• pp.845-851
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• 2000

In this paper, we show the numerical and the experimental results of two-dimensional fluid motions inside a rectangular container subjected to a background rotation added by a rotational oscillation. In the PlY experiment we apply a new algorithm, new three step search(NTSS), to the velocity calculation. In the numerical computation, the linear Ekman-pumping model was used to take the bottom friction effect into account. It was found that it well produces the experimental results at low e number.

• 대한기계학회논문집B
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• 제29권10호
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• pp.1101-1110
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• 2005

In this paper we present the numerical results of the behavior of the horizontal vortex generated by ejecting a liquid vertically upward from an orifice into the bulk fluid above the orifice. The numerical calculation has been performed for the axi-symmetric Navier-Stokes equation. A simple flow-visualization experiment was also conducted to qualitatively verify the numerical solutions. Three cases of the flow configurations studied in this paper are; firstly, the vortex was generated without any background rotation, secondly, the vortex was made under a full background rotation, and thirdly, the vortex was made during the spin-up process such that only the region adjacent to the side wall was set into motion viewed in the inertial frame of reference. It was shown that the swirl flow at the inlet boundary affects considerably the formation and development of the vortex for the second case. In the third case, it was remarkable to see that the vortex cannot penetrate into the region near to the side wall of the tank, because of the strong swirl flow and corresponding high pressure gradient in the region.

• 대한인간공학회지
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• 제32권5호
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• pp.429-435
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• 2013

Objective: This study aims to analyze job satisfaction and accident prevention according to job rotation system types in a motor company. Background: The study of a motor company's job rotation system has come to attention with enhancing productivity, preventing musculoskeletal disorders, and improving quality. Method: In this study, a survey was conducted to show job satisfaction rates according to job rotation systems. Also an investigation was done regarding industrial accidents and previous workers who are receiving treatment for musculoskeletal disorder over the last five years. Results: The job rotation system in this study has been carried out by voluntary decision of workers. Out of the job rotation types, the medium rotation complexity type had high job satisfaction whereas in a high or low rotation complexity type, which many workers prefer, led to less number of accidents and days of sick leave. Application: The results of this study are expected to be a fundamental data to job design.

• 대한인간공학회지
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• 제32권2호
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• pp.199-205
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• 2013

Objective: The aim of this study is to investigate the job rotation implementation at medium- or small-industries and to identify the viewpoint on job rotation as preventive activity of work-related musculoskeletal disorders(WMSDs). Background: Job rotation has been implemented in many industrial areas in order to prevent the WMSDs as one part of ergonomic program. Generally, the cases of implementation of ergonomic program or successful cases of job rotation were reported on the side of major or large company. Therefore, this study tried to inspect the current state of job rotation implementation at medium- or small-industries. Method: Survey was carried out for randomly contacted forty seven mangers responsible for safety. Survey contained the questionnaires on the general state of company, shift-work and job rotation. Results: The ratio of work-shift in medium- and small-industry was 34.0% and the ratio of job rotation was 19.1%. For manufacturing industry, the ratio was 37.9% and 17.2%, respectively. Conclusion: The implementation ratio of job rotation was relatively low considering the results of previous studies. Many managers appealed the quality decreasing of goods and the injuries of workers due to job rotation, though agreed to train the multi-functional worker and to prevent the WMSDs. Application: The results can be used for the fundamental data how the job rotation will be properly implemented in medium- and small-industry as an administrative control for MSDs.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.951-952
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• 2008

This paper proposes a new method for image composition which estimates the rotation angle of human hand and uses the reserved image in real-time camera images. First, we capture a background image and extract a interesting region by background subtraction. Next, we estimate the skin region from the interesting region and calculate the rotation angle of estimated skin region using PCA(Principal Components Analysis). Finally, we composite the reserved image for the calculated rotation angle in camera images. The proposed method can be applied to control the 3D avatar for marker-less augmented reality.

• 한국멀티미디어학회논문지
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• 제12권12호
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• pp.1728-1735
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• 2009

Human action tracking plays an important place in human-computer-interaction, human action tracking is a challenging task because of the exponentially increased computational complexity in terms of the degrees of freedom of the object and the severe image ambiguities incurred by frequent self-occlusions. In this paper, we will propose a novel method to track human action, in our technique, a dynamic background estimation algorithm will be applied firstly. Based on the estimated background, we then extract the human object from the video sequence, and the skeletonization method and Hough transform method will be used to detect the main structure of human body and each part rotation angle. The calculated rotation angles will be used to control a crane in the port, thus we can just control the container crane by using signalman body. And the experimental results can show that our proposed method can get a preferable result than the conventional methods such as: MIT, JPF or MFMC.