• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.941-946
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• 2002

Short reinforced concrete bridge piers are particularly susceptible to shear failure as a consequence of the high shear/moment ratio and conservatism in the flexural strength design of existing RC bridge pier, which were constructed before 1992. In addition, shear failure is brittle and involves rapid strength degradation. Inelastic shear deformation is thus unsuitable for ductile seismic response. It is, however, believed that there are not many experimental research works for shear failure of the existing RC bridge pier in Korean peninsula subjected to earthquake motions. The object of this research is to evaluate the seismic performance of existing circular RC bridge piers by the quasi-static test. Existing RC bridge piers were moderate seismically designed in accordance with the conventional provisions of Korea Highway Design Specification. This study has been performed to verify the effect of aspect ratio (column height-diameter ratio). Quasi-static test has been done to investigate the physical seismic performance of RC bridge piers, such as lateral force-displacement hysteric curve, envelope curve etc.

• Journal of the Ergonomics Society of Korea
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• v.35 no.1
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• pp.29-38
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• 2016

Objective: The purpose of this research is to extract factors affecting office lighting and their relations, and then develop a framework that helps designers research and design smart lighting systems. Background: Due to the highly specialized usages of offices, the lighting system within offices also varies according to space, work, user, etc. A framework which considers these various factors and their relations is necessary for understanding and developing smart lighting systems. Method: First we extract factors affecting office lighting conditions, and select factors that can be controlled. We then analyze and develop a structure which reflects the relations among these factors from procedural perspective. Results: We divide factors affecting office lighting into physical and social factors, and then conceptualize their relations using a circular model. We then develop our framework from procedural perspective by dividing these factors into three levels, namely Subject, Action and Object. Conclusion: The developed framework organizes various factors affecting office lighting and their relations, and helps understand the procedural and structural aspects of lighting system. Application: Our framework helps designing and refining smart lighting system for complicated office spaces by helping people understanding the overall structure of office lighting.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.207-210
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• 2001

Recently, the study on the vibration analysis of machinery is greatly important and ESPI is widely used because of its many attractive features. Firstly, ESPI can be used to measure the vibration mode shape and the phase in real-time. Secondly, the conventional measuring methode, such as accelerometers, take much time to measure the whole field of object, but ESPI needs shorter time than other methods. Because ESPI is a field-inspection method. Thirdly, ESPI is a non-contact measuring system. ESPI does not have influence on the specimen. Beyond these features, there are several advantages in ESPI system. In this paper, the Stroboscopic ESPI system is described for measurement of a vibration mode shape. The Stroboscopic ESPI system had been used to visualize the vibration mode shape, in which EO(Electro-Optic)modulator was used to chop CW(Continuous Wavefront)laser. But it was not easy to control EO modulator and quantified the vibration amplitude and the phase of circular metal plate. At first, we found resonant frequency of the specimen by using time-averaged ESPI method. Nextly, the amplitudes of specimen were quantified by using Stroboscopic ESPI and we compare the results which were obtained in several chopping ratio.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.3
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• pp.208-219
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• 2002

A novel measurement method to obtain the 6-DOF motions of arbitrary rigid bodies is proposed in this paper. The method adopts a specially fabricated mirror called 3-facet mirror, which looks like a triangular pyramid haying an equilateral cross-sectional shape. The mirror is mounted on the objects to be measured, illuminated by a laser beam having circular profile, and reflects the laser beam in three different directions. Three PSDs(position sensitive detector) detect the three beams reflected by the mirror, respectively. From the signals of the PSDs, we can calculate the 3-dimensional position and orientation of the 3-facet mirror, and thus enabling us to determine the 3-dimensional position and orientation of the objects. In this paper, we model the relationship between the 3-dimensional position and orientation of an object in motion and the outputs of three PSDs. A series of experiments are performed to demonstrate the effectiveness and accuracy of the proposed method. The experimental results show that the proposed sensing system can be an effective means of obtaining 3-dimensional position and orientation of arbitrary objects and provide resonable measurement accuracy.

• Journal of Environmental Impact Assessment
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• v.10 no.3
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• pp.175-194
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• 2001

The environment is composed of at least two components, the natural and the human-made one. Nonetheless, the environment is being used to connote the natural environment. Moreover, even though the components of environment exist in a mutual relationship as a mechanism, it is rare to study the components of environment and their system as a mechanism. With such an implication, this paper aims to identify the components of environment and their system. The components of environment can be categorized by two criteria. One is the subject of creating environment, and the other is the visuality of environment. The former categorizes the environment into the natural and the human-made one, and the latter into physical and nonphysical one. Integrating the two criteria into a framework, the environment can be categorized into the natural, the human-made physical, and the human-made nonphysical environment. The three categories of environment exist interrelatedly in a mechanism being characterized as a mutual impact. The mechanism may be called the environmental system. The environmental system can be analyzed in terms of two dimensions. One is a human-inclusive system. The other is a human-centered system. The former is a framework that includes humans as a component of environment. The latter is a framework that humans are the subject of the environment, and the others surrounding human life are the object of the environment. The former is defined as a circular system of material and energy, while the latter is defined as a mutual subjective-objective system.

• The Journal of Korean Physical Therapy
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• v.8 no.1
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• pp.1-14
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• 1996

The present case study has a object to investigate the changes in locomotion patterns of infant with athetoid cerebral palsy would be occured by the program when it is applied with upper extremity weight bearing. The subject has been limited to one infant over one year of age, selected from the patients in the physical therapy clinic, Rehabilitation Center, Taegu University. Subject is normal in the visual and auditory sense, but he is unable to walk on his own Subject weighted 2.9kg at birth and underwent severe postnatal kernicterus, always on the baby-walker at homo. He disliked supine position characteristic in moving in athetoid type before he was under the program. The program was applied 7 months. Each session of the program is composed of 7 stages : (1) prebriefing between the therapist and the parents (2) pretherapy amusement time of the infant (3) warming-up (4) upper extremity weight bearing (5) cooling-down (6) post-therapy amusement time (7) postbriefing. The locomotion of the subject is proved to be influenced by the program. He showed a leftward circular movement as a result of the exercise, reducing the involuntary movement of his head when he was positioned for crawling. Later he proceeded to develop into creeping, crawling, kneeling and finally cruising. In conclusion, it appeared evident that the locomotive abilities of the subject is improved by the program explored in this study. The higher locomotive patterns could be achieved such as crawling, sitting, kneeling and cruising wich enable the upper extremities weight bearing.

• Journal of the Korea Safety Management & Science
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• v.17 no.4
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• pp.105-112
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• 2015

Sawmilling industry remained a high risk with the average 4.73% of industrial accidents in 2010-2012 that was eight times that of general manufacturing. Sawmilling industry had 200 industrial accidents victim in average. Manufacturing process in sawmill industry contained dangerous machinery such as conveyors, roller, saw ( band saw, circular saw) etc. It may be effective to figure out the type of industrial accidents occurred in the past and extend risk assessment which can predict hazard such as near miss when implementing exposure or potential dangers in sawmill industry. This study conducted research on the actual condition on the place of industrial accident occurrence, detailed work and contact object when injured, and injured part targeting 643 businesses which had industrial accidents in 2010-2012. As the results, RPN of general sawmill industry was the highest 'ganglip saw' with 36,157. RPN of the following order were 'moving truck' with 25,454, 'special machining operations' with 22,283. Also, probability of general sawmill industry was a lots within 1 year, while risk appeared a lots within 5 years. So, risk assessment shall be needed to emphasis on accident prevention of sawmill industry. And additional work will be needed on the risk assessment in hazard prevention work of supervisors.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.1
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• pp.62-71
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• 2001

Prediction of ship's signature of RCS(Radar Cross Section) and TES(Target Echo Strength) is mostly required in the initial design stage of naval craft, because RCS is directly related to the radar detection while TES to the sonar detection. In this research, a numerical scheme using a curved-patch physical optics method is proposed to evaluate signature of a perfectly reflecting curved object. The scheme is validated by comparing numerical RCS values of circular cylinder, sphere and NACA3317 airfoil with available data. It is also further applied to predict RCS of a surfaced submarine and TES of fully submerged one. Major reflectors of the surfaced or submerged submarine for the various incident angles of radar and sonar waves are investigated as well.

• Journal of Biomedical Engineering Research
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• v.43 no.1
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• pp.35-44
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• 2022

Immersed boundary-Lattice Boltzmann Method (IB-LBM) is used for the analysis of flow over the circular cylinder in the concept of fluid-structure interaction analysis (FSI). Recently, IB-LBM has shown the enormous possibility for the application of various biomedical engineering fields, such as the movement of a human body or the behavior of the blood cells and/or particle-based drug delivery system in blood vessels. In order for the numerical analysis of the interaction between fluid and solid object, immersed boundary method and lattice Boltzmann method are coupled to analyze the flow over a cylinder for low Reynolds laminar flow (Re=10, 20, 40 and 100) with Zhu-He boundary condition at the boundary. With the developed IB-LBM, the flow around the cylinder in the uniform flow is analyzed for the laminar flow and the drag and lift coefficients and recirculation length are compared to the previous results.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.5
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• pp.624-631
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• 2008

This paper presents a method for a mobile robot to follow a moving object in real time. The robot follows a target object keeping the facing angle toward the target and the distance to the target to given value. The method consists of two procedures: first, the detection of target position in the robot coordinate system, and the second, the calculation of translational velocity and rotational velocity to follow the object:. To detect the target location, range sensor data is represented in histogram. Based on the real time calculation of the location of the target relative to the robot, translational velocity and rotational velocity to follow the target are calculated. The velocities make the heading angle and the distance to target converge toward the desired ones. The performance of the method is tested through simulation. In the simulation, the target moves with three different trajectories, straight line trajectory, rectangular trajectory, and circular trajectory. As shown in the results, it is inevitable to lose track temporarily of the target when the target suddenly changes its motion direction. Nevertheless, the robot speeds up to catch up and finally succeeds to follow the target as soon as possible even in this case. The proposed method can also be utilized to coordinate the motion of multiple robots to keep their formation as well as to follow a target.