• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.170-174
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• 1999

In order to analysis contact mechanism of head/ disk interface on hard disk drive, many techniques of analysis have been developed. Acoustic Emission sensor can be used for detect elastic energy of contact at head/disk interface. This work presents a good understanding of slider characteristics in frequency domain. The results show that torsional and bending mode of slider are dominant in head/disk contact.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.361-371
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• 2005

The confined concrete subjected multi-axial stresses have been known as the fact it increases strength of concrete significantly compared with unconfined concrete. Many researchers have studied in confining effects of concrete, and now are studying in many fields. Although many researches about confined concrete using FRP have been studied recently, it is difficult to apply concrete confined by FRP in real structures because FRP is a brittle material. To investigate the influence of concrete strength and ductility increased by confining stiffness in steel, this study was tested and compared with 51 specimens confined by different shapes and thicknesses of steel tube. This test verified the increasement of strength and ductility in confined concrete. Also, analyzing the experimental data by regression method, this study provides stress-strain model about CSS and R4S considering effect of confinement stiffness on the stress-strain relations of concrete.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.303-309
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• 1999

Optimum tribological performance of the head/disk system is critical in maintaining reliable data processing in a hard disk drive. Particularly, as the flying height of the slider continues to decrease with increasing recording density, frictional interaction between the slider and the disk need to be better understood. In this work the effect of reduced ambient pressure on the tribological behavior of the head/disk interface is presented. It is found that surface damage of the components can be accelerated by reducing the ambient pressure. This method may be utilized to assess slider/disk compatibility of newly developed systems in short time.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.192-195
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• 2003

As a part of our research project for in-situ bioremediation of nitrate contaminated. groundwater, screening studies to determine an effective electron donor (EO) and/or carbon source (CS) such as acetate, ethanol, formate, fumarate, lactate, and propionate were conducted. To evaluate the feasibility for the biological degradation of nitrate, soil microcosm studies using nitrate-contaminated soil and groundwater were performed. The nitrate removal percentage in the order from the highest to the lowest was: formate, fumarate, and ethanol > lactate > propionate. Essentially no nitrate consumption was observed In acetate-fed microcosms. The order of nitrate removal rate from the highest to lowest was fumarate, formate, lactate, ethanol, and propionate. These results suggest that fumarate and formate are promising EDs/CSs for in-situ bioremediation of nitrate - contaminated oxygenated groundwater.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.39-50
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• 2014

PURPOSES : The objective of this study is to evaluate the curing and adhesive behavior of asphalt emulsions including polymer-modified emulsions for chip seals and fog seals. METHODS : For the laboratory testing, the evaporation test, the bitumen bond strength (BBS) test, and the Vialit test are used. Also, the rolling ball test and the damping test are employed to evaluate the curing properties of the fog seal emulsions. In order to conduct all the tests in controled condition, all test procedures are performed in the environmental chamber. The CRS-2L and the SBS CRS-2P emulsions are used as a polymer-modified emulsion, and then unmodified emulsion, the CRS-2, is compared for the evaluation of chip seal performance. For the fog seal performance evaluation, two types of polymer-modified emulsions (FPME-1 and FPME-2) and one of unmodified emulsion, the CSS-1H, are employed. All the tests are performed at different curing times and temperatures. RESULTS AND CONCLUSIONS : Overall, PMEs show better curing and adhesive behavior than non-PMEs regardless of treatments types. Especially, the curing and adhesive behavior of PMEs is much better than non-PMEs before 120 minutes of curing time. Since all the test results indicate that after 120 minutes of curing time the curing adhesive behavior of emulsions, the early curing time, i.e., 120 minutes, plays an important role in the performance of chip seals and fog seals.

• The Journal of the Convergence on Culture Technology
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• v.4 no.3
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• pp.185-190
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• 2018

In the recent field of education, they open career-related curriculums either as formal curricular programs or extracurricular programs as highlighting value of career education. However, this lecture-based career education has failed to attract students' interest, and results are not satisfactory either. Since then, in order to design entertaining career education, the field has developed diverse tools and as a vocational aptitude testing tool for career development, methods that would use vocational cards were introduced. Today, schools from elementary school to middle and high schools frequently make use of the cards to conduct the vocational aptitude test and yet, as this web-based learning and smartphones are distributed, changes in the testing tool are being intensely demanded. This study aims to create and implement an application to help the vocational cards-using vocational aptitude test targeting students in elementary, middle and high schools to be actually conducted in a mobile platform.

• Journal of Korean Academic Society of Home Health Care Nursing
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• v.10 no.2
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• pp.123-131
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• 2003

This study was to compare the functional status. complication and readmission rates. and client satisfaction with nursing care of home-based care and hospital-based care for clients with Coronary Artery Bypass Graft. Raw data were collected by interviewing and reviewing charts of 41 clients with Coronary Artery Bypass Graft between June 2001 and July 2002 at an university hospital located in Seoul. Korea. Out of 41 clients. 15 were in home care group and 26 were in hospitalization group. The baseline characteristics of the groups were almost identical. Mean age was 61.7 and 75.6% of clients being male. For home care group. the data collection was made at discharge and at termination of home care. and for hospitalization group. at discharge and at the first visit of outpatient department. Complication and readmission rates were investigated at one month after operation. Collected data were then analysed by conducting Chi-square test. Wilcoxon rank sum test. and Wilcoxon signed ranks test with SPSS program. The level of significance was .05. The results of the study are summarized as follows: 1. Postoperative length of stay of the home care group was shorter than that of hospitalization group by 1. 14 days(8.45 days vs. 9.59 days). On average. 1.8 home visits per client were observed. 2. The functional status (Barthel Index) at the termination of home care was significantly increased from that at discharge. For hospitalization group. a significant increase was observed between the functional status at the discharge and that at the first visit of outpatient department. The differencies in incremental of the scores. between the groups. were however not significant. 3. Complication and readmission rates; no statistically significant difference between the groups was observed. 4. The client satisfaction with nursing care (CSS) at termination of home care was significantly higher than that at hospital discharge. In conclusion. the outcomes of the analysis suggest that the home care benefits clients with Coronary Artery Bypass Graft. Client satisfaction with nursing care rises at termination of home care as compare to that measured at hospital discharge. Meanwhile. there was no significant differences in functional status. and complication and readmission rates. Further. home care reduced the length of stay in hospital.

• The Journal of Korea Robotics Society
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• v.6 no.1
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• pp.58-68
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• 2011

This paper proposes a technique of indoor localization for mobile robot by so called indoor GPS and EKF. Basically the concept of indoor GPS is similar outdoor GPS, and the indoor GPS gets distances between Anchors and Tag by a ranging method of CSS and then estimates the coordinate by distances and known Anchor positions. After we performed performance test of indoor GPS system in ideal and multipath environment, we configured that the indoor GPS has internal error factors and external error factors. This paper handled a multipath problem belonging to external error factors. At first various direct physical method are introduced to fix the multipath problems, and as expected we got errors corrected considerably. And then the method of selective anchors for indoor GPS is applied. With these two level improvement of indoor GPS performance, EKF(Extended Kalman Filter) is applied to mobile robot in indoor environment. The usefulness of the proposed methods are shown by a series of experiments in a environment giving contaminated data by multipath.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.930-935
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• 2001

The experimental characterization of hydrodynamic bearing spindle motor is performed for the practical implementation of high-performance hard disk drive system. Firstly, the design concept of hydrodynamic bearing for the disk drive system is addressed including the herringbone grooved journal bearing, the spiral grooved thrust bearing, capillary seal design, and the viscous pumping of fluid. Secondly, the experimental evaluation is performed for the disk drive system in which the hydrodynamic bearing spindle motor is implemented and its dynamic performances are compared with conventional ball-bearing spindle motor. The key parameters include NRRO(Non Repeatable Run-Out), disk dynamics, acoustics, and resultant PES (Position Error Signal). Finally, the external gyro-exciting test results including 200k CSS(Continuous Start-Stop) on three angular attitudes(0,90, 180 degree) are presented in order to verify the practical reliability of disk drive system subject to the gyro-motion of hydrodynamic bearing spindle motor.

• Korean Journal of Health Education and Promotion
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• v.20 no.2
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• pp.1-18
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• 2003

The purpose of this study was to develop game style courseware in oral health instruction for elementary school children. The manufacturing equipment and languages which were used to develop the courseware were： Photoshop version 7.0, Illustrator version 10.0, HTML, Dream Weaver MX, Editplus, CSS and Java - script. The data base was built up by using PHP and mySQL over Internet Explorer version 4.0. The contents of courseware for oral health education were based on the list of oral health affaires of the Department of Health and Welfare, 2002. The story of the game ‘Saving Hayani locked down in a castle of a cavity man’ was developed for the learners to learn oral health by inducing learning motivation. A character named ‘Chan i’ was introduced to the learners to be more friendly with the program while they were learning. As the game was made of three step education levels, the learner most pass the prepared test given at each step to advance to a higher level. A database connected to web was constructed to store the scores the learners earned at each step. In conclusion, the courseware will help the elementary school children learn oral health care efficiently through the internet regardless of time and space.