• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.299-308
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• 2011

In this study, we develop a pressure observer to measure the cylinder length of a harbor-construction robot. For the robot control, sensors are required to measure the length of a hydraulic cylinder. The cylinder-position sensor is relatively expensive when the operating environment prohibits external approaches for the measurement of the cylinder position. LVDT or linear scales are usually mounted on the outside of the cylinder, which causes poor durability on a construction site. We use a pressure sensor to indirectly estimate the length of the cylinder. The pressure sensor is mounted inside a hydraulic valve box so that it is protected by the box and easy to waterproof for an underwater robot. By treating oil as a compressible fluid, we derive the nonlinear pressure dynamics as a function of the cylinder position, velocity, and pressure. The recursive least squares (RLS) algorithm is applied to identify the dynamic parameters, and the pressure observer estimates the cylinder position through the pressure acting on the head and the rod of the hydraulic cylinder. The position accuracy is relatively low, but it is acceptable for a construction robot that handles large armor stones.

• The Korean Journal of Pesticide Science
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• v.4 no.4
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• pp.1-11
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• 2000

Since the chemical pesticides have been played a major role in crop protection practices during last 5 to 7 decades, social concerns on the pesticide residues in and on food commodities as well as environmental compartments have also growing with endless demands and interests. Most national regulation authorities over the world have paid a special attention on the data requirements for pesticide registration. In addition, even the registered pesticides also should follow the re-registration process, which meets today's guidelines and regulatory triggers and safety profiles. More recently, a defined interest in the international bodies has given to the global conservation program from the environmental contamination; these involves persistent organic pollutants (POPs), endocrine disrupting chemicals (EDs), biocides, etc.. In order to secure the food safety and keep our circumference sound, in-depth efforts getting information from global networks have perpetually to be given under relevant national agencies. At the same time, a nation-wide survey of the residues has also to be in operation to monitor the tendency of the toxicant in/on foods, feeds, and environmental segments. In final, the scientifically assessed results on safety should be opened to the public to provide the right-to-know for the consumers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.161-166
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• 2014

Recently, indoor sports simulator equipped with virtual reality devices, like screen golf system, are riding high. There have been many attempts to develop the indoor simulator systems which can make people enjoy exercises in various sports area. A real horseback riding could not have been popularized, because of the cost involved, difficulty to learn and its dangerousness. In this research, a robotic horseback riding platform based on parallel mechanism and virtual reality device is proposed. The proposed platform provides realistic riding feels and various levels of riding difficulty. The equipped motion capture system with a vision sensor enables riders to correct their riding posture based on expert's one. The developed horseback riding platform make it possible to enjoy a horseback riding in all weather, and also can be used for systematic horseback riding training.

• Journal of Biomedical Engineering Research
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• v.25 no.2
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• pp.97-102
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• 2004

We developed an x-ray cone-beam micro computed tomography (micro-CT) system for small-animal imaging. The micro-CT system consists of a 2-D flat-panel x-ray detector with a field-of-view (FOV) of 120${\times}$120 mm2, a micro-focus x-ray source, a scan controller and a parallel image reconstruction system. Imaging performances of the micro-CT system have been evaluated in terms of contrast and spatial resolution. The minimum resolvable contrast has been found to be less than 36 CT numbers at the dose of 95 mGy and the spatial resolution about 14 lp/mm. As small animal imaging results, we present high resolution 3-D images of rat organs including a femur, a heart and vessels. We expected that the developed micro-CT system can be greatly used in biomedical studies using small animals.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.138-147
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• 2001

Alignment systems are frequently used under various semiconductor manufacturing environment. Particularly in PDP(Plasma Display Panel) manufacturing process, the alignment system is applied to the combining and sealing processes of the upper and lower glass panels of PDP, where these processes are performed in the vacuum chamber of high vacuum and high temperature. In this paper, the XYΘ-alignment stage is developed to align PDP panels. Because of high vacuum and high temperature environment, the alignment chamber has been designed to isolate the inner part of the alignment chamber from the outer environment of high vacuum and high temperature, in which every part of the alignment stage is inserted. As it is difficult to attach feedback sensors to the alignment stage in the alignment chamber, the alignment stage is implemented with the open loop algorithm, where the parallel link structure has been designed using step-motors and ball-screws for structural simplicity. The kinematic analysis is performed to drive the parallel link structure, based on the experiments of actuation-compensation of the alignment stage. For the error compensation, the hyperpatch model has been used to model the errors. From the experiments, the positional accuracy of the alignment stage can be improved significantly.

• Journal of Biomedical Engineering Research
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• v.25 no.6
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• pp.505-510
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• 2004

In this article, we present an automated system for adjusting the 6 degree of freedom (D.O.F.) circular fixator. The system includes a scheduling software to adjust the Hexapod Circular Fixator (HCF) and an automated strut with the ability of the multiple synchronized motion and independent motion. The HCF was designed to control a 6 D.O.F. Ilizarov fixator and it's mechanism. The HCF adjustment software evaluates each value of altered length of the HCF struts to correct the complex skeletal deformity by using the X-ray data of the patient. The data of HCF adjustment software feed into the automated strut system which provides the scheduled adjustment. Then, the automated strut is synchronized by input data. Also the data of HCF adjustment software can be used to adjust HCF without automated struts. The proposed HCF system was verified by experiments.

• The Journal of the Korea Contents Association
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• v.22 no.3
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• pp.212-221
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• 2022

This study aimed to analyze the relationship between ADHD trait and life satisfaction among male adolescents, and to examine the mediating effect of interpersonal initiation and internet game addiction on that relationship. The participants were 285 male students from middle and high schools. For this study, World Health Organization ADHD Self-Report Scale, Interpersonal Competence Questionnaire, Internet Gaming Use-Elicited Symptom Screen, and Satisfaction with Life Scale were used. PROCESS Macro 3.5 Model 4 was used to analyze a double mediating effect. Results revealed that male adolescents' ADHD trait was negatively correlated with interpersonal initiation and life satisfaction, while it was positively correlated with their internet game addiction. And, male adolescents' interpersonal initiation was positively correlated with life satisfaction, whereas internet game addiction was negatively correlated with life satisfaction. In addition, male adolescents' interpersonal initiation and game addiction were mediating ADHD trait and life satisfaction. These findings suggest that the interpersonal initiation and game addiction should be treated to improve life satisfaction of male adolescents with high ADHD trait.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.193-204
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• 2008

This paper describes laboratory experiments modelling multiple tunnel construction in soft ground. A series of small-scale model tests have been conducted at approximately 1/50 scale in order to investigate the behaviours of existing tunnels in response to the construction of new tunnels in close proximity. The model tunnels were constructed in a consolidated Speswhite Kaolin clay using a tunnelling device involving an auger type cutter within a shield. Strain gauges and LVDTs were used for instrumenting the existing tunnels. The findings obtained from the analyses of these tests were compared to the field measurements involving the reconstruction of the Northern Line London Underground Ltd. tunnels at Old street, United Kingdom. The results were also compared to the ground movement measurements obtained from a separate set of tests undertaken using the same apparatus and experimental procedures.

• Journal of Korean Elementary Science Education
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• v.23 no.4
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• pp.344-356
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• 2004

In this study, we developed the program for 'Discretionary Activity' focusing on the multiple activities with everyday-life materials to enhance scientific creativity (MAEM-SC), which was specifically for students in the 6-7th grade according to the 7th curriculum in Korea. As important factors for scientific creativity, we selected the ability to find out the context relevant to scientific problems, the ability to connect the problem context to scientific knowledge, the ability to invent the ways to solve the problem scientifically, and ability to concentrate on the scientific problem solving activity. The topics of the program were drawn from common and familiar things in our everyday contexts, such as human body, everyday tools, food, play and toys, and everyday episodes. The multiple activities here mean the activities which are systematically constructed with the various types of activities with a specific intention. The multiple activities were designed in three types, that is, series type, parallel type, and combination type. Each of them consists of the several activities as follows: estimating and measuring, carrying out an experiment using body, inventing implement (tools), thinking statistically, writing creatively with scientific themes, and connecting one concept to another concept etc. Through a trial of the program, we found that this program has some positive influence on the enhancement both of the ability to find out the context relevant to scientific problems and the ability to connect it to the students' existing scientific knowledge.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.51-59
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• 1993

This paper develops practical and realistic reliability models and methods for the evaluation of system-reliability and system reliability-based rating of various types of box-girder bridge superstructures. The strength limit state model for box-girder bridges suggested in the paper are based on not only the basic flexural strength but also the strength interaction equations which simultaneously take into account flexure, shear and torsion. And the system reliability problem of box-girder superstructure is formulated as parallel-series models obtained from the FMA(Failure Mode Approach) based on major failure mechanisms or critical failure states of each girder. In the paper, an improved IST(Importance Sampling Technique) simulation algorithm is used for the system reliability analysis of the proposed models. This paper proposes a practical but rational approach for the evaluation of capacity rating in terms of the equivalent system-capacity rating corresponding to the estimated system-reliability index which is derived based on the concept of the equivalent FOSM(First Order Second Moment) form of system reliability index. The results of the reliability evaluation and rating of existing bridges indicate that the reserved reliability and capacity rating at system level are significantly different from those of element reliability or conventional methods especially in the case of highly redundant box-girder bridges.