• Geomechanics and Engineering
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• v.20 no.5
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• pp.433-445
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• 2020

A new code, called PRaFULL (Piled Raft Foundation Under Lateral Load), was developed for the analysis of laterally loaded Combined Pile Raft Foundation (CPRF). The proposed code considers the contribution offered by the raft-soil contact and the interactions between all the CPRF system components. The nonlinear behaviour of the reinforced concrete pile and the soil are accounted. As shallower soil layers are of great relevance in the lateral response of a pile foundation, PRaFULL includes the possibility to consider layered soil profiles with appropriate properties. The shadowing effect on the ultimate soil pressure is accounted, when dealing with pile groups, as proposed by the Strain Wedge Model. PRaFULL BEM code obviously requires less computational resources compared to FEM (Finite Element Method) or FDM (Finite Difference Method) codes. The proposed code was validated in the linear elastic range by comparisons with the code APRAF (Analysis of Piled Raft Foundations). The reliability of the procedure to predict piled raft performance was then verified in nonlinear range by comparisons with both centrifuge tests and computer code PRAB.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.237-242
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• 2001

Residual stress is a dominant obstacle to efficient production and safe usage of products by reducing the mechanical strength and failure properties. Especially, it causes interfacial failure and substrate deflection in the case of thin film. So, the exact evaluation and optimum control of thin film residual stress is indispensable. However, hole drilling or X-ray diffraction techniques have some limits in application to thin film. And, curvature technique for thin film materials cannot give the information about local stress variation. Therefore, we applied the nanoindentation technique in evaluating the thin film residual stress. In this study, we modeled the change of indentation loading curve for residually stressed and stress-free thin films during stress relaxation. The value of residual stress was directly related to the indentation depth change by relaxation. The residual stress from nanoindentation analysis was consistent with the result from curvature technique.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.2
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• pp.261-271
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• 1997

This paper presents the design process and characteristic test results of tension sensors for measuring the ultimate tension forces of surgical wires. Three types of sensor were designed and tested for calibration. The first two types which transfer the wire tension to the sensing element by direct contact have too much hysterisis errors due to the firctional effect. This error can be considerably reduced in the modified structure, where a cover and a loading button is used to transfer force and moment to the sensing element. The strains predicted by theoretical equations agree well with those by finite element calculations neglecting friction and the strains by finite element analysis considering friction are in good agreement with those measured by four strain gages. The modified ring type tension sensor developed in this paper is expected to be useful for measuring the tension of surgical wires with nonlinearity of 1.31%FS, hysterisis of 5.74%FS and repeatability of 0.19%FS.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.402.1-402.1
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• 2014

Photonic force microscopy (PFM) is an optical tweezers-based scanning probe microscopy, which measures the forces in the range of fN to pN. The low stiffness leads proper to measure single molecular interaction. We introduce a novel photonic force microscopy to stably map various chemical properties as well as topographic information, utilizing weak molecular bond between probe and object's surface. First, we installed stable optical tweezers instrument, where an IR laser with 1064 nm wavelength was used as trapping source to reduce damage to biological sample. To manipulate trapped material, electric driven two-axis mirrors were used for x, y directional probe scanning and a piezo stage for z directional probe scanning. For resolution test, probe scans with vertical direction repeatedly at the same lateral position, where the vertical resolution is ~25 nm. To obtain the topography of surface which is etched glass, trapped bead scans 3-dimensionally and measures the contact position in each cycle. To acquire the chemical mapping, we design the DNA oligonucleotide pairs combining as a zipping structure, where one is attached at the surface of bead and other is arranged on surface. We measured the rupture force of molecular bonding to investigate chemical properties on the surface with various loading rate. We expect this system can realize a high-resolution multi-functional imaging technique able to acquire topographic map of objects and to distinguish difference of chemical properties between these objects simultaneously.

• The Journal of Korean Physical Therapy
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• v.23 no.2
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• pp.1-5
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• 2011

Purpose: This study examined the difference in the center of pressure (COP) displacement time in older adults according to the obstacle height during stance at each sub.phase when crossing obstacles. Methods: Fifteen older adults were enrolled in this study (${\geq}65$ years of age). The F-scan was used to measure the COP displacement time when crossing a 0, 10 and 40cm obstacle, and the stance phase was divided into 4 sub-phases according to the foot contact pattern. Results: During the stance phase, the COP displacement time increased with increasing obstacle height. During the mid-stance, terminal stance and pre-swing except for the loading response, there were significant differences in the COP displacement time according to the obstacle height. Conclusion: This study suggests that older adults show differences in the COP displacement time according to the stance sub-phase while crossing obstacles, and they use different mechanisms according the sub-phases to maintain balance during obstacle crossing.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.1
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• pp.123-133
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• 2003

The specific objectives of the study were as follows: 1) To investigate the composition system (design, usability and interactivity) of web sites of textile exchange of B to B 2) To examine and valuate contents and marketing (announcement, satisfaction and variety of contents) of web sites of textile exchange of B to B. The data were collected from search engine, portal sites of evaluation, direct contact, interview over the phone with web master of concerned web sites and the result of analytical valuation of web sites. The results of this study were as fellows: 1) The Dongsung trading intended to mainly use their homepage as a inside communication place by intranet network. The Daechang trading was mainly using their homepage as a tool of expansion of their outside export market. The etextiler was selling their web solutions through homepage. The texcom was offering the web place and useful informations to trading companies in Asia. 2) The texcom consisted text with little image to speed up for loading and navigation for usability of users. The Dongsung trading made intranet network for communication and exchange of informations of company inside. The etextiler offered a booking menu to inquiry in homepage. The Daechang trading tried to give good impression from the introduction page at homepage.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.127-134
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• 2020

The adsorption characteristics of the major tar compound, acenaphthene, derived from Taxus chinensis by the commercial adsorbent Sylopute were investigated using different parameters such as initial acenaphthene concentration, adsorption temperature, and contact time. Out of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models, adsorption data were best described by Langmuir isotherm. The adsorption kinetics was evaluated by pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The pseudo-second-order model was found to explain the adsorption kinetics most effectively. Thermodynamic parameters revealed the feasibility, nonspontaneity and exothermic nature of adsorption. In addition, the isosteric heat of adsorption was independent of surface loading indicating the Sylopute used as an energetically homogeneous surface.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1514-1518
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• 2009

Recently, railroad construction has been increased all over the world and as the train is getting high-speeded, there has been a need for guaranteed safety, so that a requirement for heath monitoring techniques for destruction that generated by gradually accumulated damages is now increasing. Especially the rail is crucial part that contact with wheel directly and delivers the train's load to a sleeper. It needs a technique that can guarantee a safety by sensing the possible cracks. In this paper, when train's load applied to the rail, strain distribution that introduced to entire length of rail is monitored using optical fibre. Optical fibre is used as a medium for measuring the strain and BOCDA (Brillouin Optical Correlation Domain Analysis) system is organized for measuring the distributed variation that implied to optical fibre. Optical fibre is attached at lower flange where tension is maximized when the load of train applied to the rail and strain gauge is implied together to compare the accuracy of measurement.

• The KSFM Journal of Fluid Machinery
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• v.20 no.2
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• pp.63-68
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• 2017

This paper predicts the rotordynamic force coefficients of tilting pad journal bearings (TPJBs) with ball-socket pivot and compares the predictions to the published test data obtained under load-between-pad (LBP) configuration. The present TPJB model considers the pivot stiffness calculated based on the Hertzian contact stress theory. Due to the compliance of the pivot, the predicted journal eccentricity agree well with the measured journal center trajectory for increasing static loads, while the early prediction without pivot model consideration underestimates it largely. The predicted pressure profile shows the significant pressure development even on the unloaded pads along the direction opposite to the loading direction. The predicted stiffness coefficients increase as the static load and the rotor speed increase. They agree excellently with test data from open literature. The predicted damping coefficients increase as the static load increases and the rotor speed decreases. The prediction underestimates the test data slightly. In general, the current predictive model including the pivot stiffness improves the accuracy of the rotordynamic performance predictions when compared to the previously published predictions.

• Journal of Periodontal and Implant Science
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• v.34 no.3
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• pp.535-541
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• 2004

The aims of the present study are firstly to investigate the amount of bone loss around non-submerged implants placed in the posterior region and secondly to investigate the relationship between inter-implant and implant-tooth distance and peri-implant bone loss. Thirty-one subjects with 60 implants were selected consecutively from the implant patient pool at the department of Chonbuk National University Hospital. To be included in the study subject, the implant should have been functioned more than 6 months after loading. Inter-implant and implant-tooth distance, distance between implant shoulder and the first bone contact with the implant(DIB) were measured from the scanning image of the radiograph of each implant. The result showed that; 1. inter-implant distance has a statistically significant relationship with DIB in Pearson correlation analysis. 2. the DIB at the implant facing surface of the implant was greater than that of tooth facing surface of the implant. Within limitation of this study, it is suggested to place an implant not too closely to adjacent implants, and the presence of a tooth adjacent to an implant may keep the level of tooth-facing surface of the implant. Further studies with a prospective design are needed to elucidate the relationship between bone changes and various dimensions around implants.