• Journal of the Korean Society for Precision Engineering
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• v.29 no.10
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• pp.1056-1061
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• 2012

FEM analysis is essential to shorten the development time and reduce the cost for developing high-performance machine tools. Mount joint parts play important role to ensure static and dynamic stability of machine tools. This paper suggests a computational modeling of mount joint part of machine tools. MATRIX27 element of ANSYS is adopted to model mount joint parts. MATRIX27 allows the definition of stiffness and damping matrices in matrix form. The matrix is assumed to relate two nodes, each with six degrees of freedom per node. Stiffness and damping values of commercial mount products are measured to build a database for FEM analysis. Jack mounts with rubber pad are exemplified in this paper. The database extracted from the experiments is also used to estimate of stiffness and damping of untested mounts. FEM analysis of machine tools system with the suggested mount computational model is performed. Static and dynamic results prove the feasibility of the suggested mount model.

• The Journal of Korea Robotics Society
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• v.15 no.2
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• pp.177-183
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• 2020

Collaborative Robot (Cobot) that can collaborate with humans by fusion with many advanced technologies among industrial robots in the industrial field are attracting attention. In this study, the engineers of Small and Medium Enterprises can directly participate in the cobot design, and ultimately, the possibility of deriving the shape design of the differentiated cobot was studied. The method applied to derive the shape design of differentiated cobot is 'Morphological Analysis'. First, the design elements of the form of cobots were derived as 'Link' and 'Joint'. In addition, by analyzing the image form of the Link and Joint of the existing cobot, a new form element of the Link and Joint was proposed. In order to quantitatively identify the most discriminating cobot shape design, FGI (Focus Group Interview) was conducted to derive image types of 4 Link and 3 Joint. Then, the most important 'Shape Combination' was carried out in morphological analysis, and 12 new cobot shape designs were drawn. Through this, the applicability of the morphological analysis method in the derivation of differentiated cobot shape design was examined.

• Journal of Biomedical Engineering Research
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• v.31 no.2
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• pp.141-150
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• 2010

The purpose of this study was to analyze the golf swing motion for a soft golf clubs and regular golf club. Soft golf is a newly developed recreational sports for all ages, including the elderly and the beginners of golf. To quantify the effect of using soft golf club, which much lighter club than regular clubs, a motion analysis has been performed using a 3D optoelectric motion tracking system that utilizes active infrared LEDs and near-infrared sensors. The subject performed swing motion using a regular golf club and a soft golf club in turn. The obtained motion capture data was used to build a 3D computer simulation model to obtain left wrist, elbow shoulder and lumbar joint force and torque using inverse and forward dynamics calculations. The joint force and torque during soft golf swing were lower than regular golf swing. The analysis gave better understanding of the effectiveness of the soft golf club.

• Computers and Concrete
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• v.10 no.5
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• pp.469-487
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• 2012

This paper presents a study on the behaviour of the joints of segmental concrete bridges with external prestressing, focusing on the structural response of dry non-epoxied joints with shear keys. A Finite Element joint model to study such structures is validated modelling eight concrete panel tests. The most important feature of this model is that it has been validated with experimental tests on concrete panels which were specifically designed to fail in shear. Interface elements are used to reproduce the non linear behaviour of the joint and parameters deduced from the tests are used to define the constitutive law of these elements. This joint model is of great importance because it will permit the development of a structural model that faithfully reproduces the behaviour of these structures under combined flexure and shear and the study of its global behaviour after the opening of the joints. Interesting conclusions about the behaviour of the dry joints, about the contribution of the different mechanisms transferring shear (friction and cohesion) and about the shear stress distribution in the joint have been reached.

• Tunnel and Underground Space
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• v.12 no.4
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• pp.268-276
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• 2002

In this study, a 3D coordinate measurement system equipped with a laser displacement meter for digitizing rock joint surface was established and the digitized data were used to calculate several roughness parameters. The parameters used in this study were micro avenge inclination $angle(i_{ave})$, average slope of joint $asperity(SL_{ ave})$, root mean square of $i-angle(i_{rms})$, standard deviation of height(SDH), standard deviation of $i-angle(SD_i)$, roughness profile $index(R_P)$, and fractal dimension(D). The relationships between the roughness parameters based on the digitzation of the surface profile were analyzed. Since the measured value varied according to the degree of reflection and the variation of colors at the measuring point, rock joint surface was painted in white to minimize the influence of the surface conditions. The comparison of the measured values and roughness parameters before and after painting revealed the better consequence from measurement on the painted surfaces. Also, effect of measuring interval was studied. As measured interval was increased, roughness parameters were exponentially decreased. The incremental sequence of degree of decrease was $SDH\; i_{ave},\; i_{rms},\; SD_i,\;and\; R_ p-1$. As a result of comparison of parameters from pin-type measurement system and laser type measurement system, all value of parameters were higher when laser-type measurement system was used, except SDH.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.3
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• pp.260-265
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• 2013

To increase the machine accuracy by improving the stiffness of spindle bearings, preload was applied to the spindle bearings. The methods of fixed position preload, convertible preload, constant pressure preload, and variable preload are used to apply the preload to the spindle bearing. The previous studies performed by the author of this study were variable preload methods using rubber pressure and centrifugal force based on mechanical systems. This study proposed a toggle joint mechanism that could be applied to variable preload method using centrifugal force and rubber pressure to increase the preload. Also, a finite element analysis was conducted to predict the deformation of the rubber and change of the preload. And the analysis results showed that the preload by the device using rubber pressure only was increased by the toggle joint mechanism using rubber pressure.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.3
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• pp.313-318
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• 2012

Application of composite structures on naval ships strongly depends on the mechanical strength and collapse behavior of the T-joints of the whole structure. Because of the weight advantages over single skin composite and bolt fastening joining, three types of T-joints using both honeycomb sandwich composite and adhesive bonding were suggested to determine the effect of T-joint configuration. It was found that joining with a urethane foam block and overlaminates using the secondary co-bonding technique improves T-joint strength.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.193-202
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• 2014

The comprehensive review of the STCW 1978, as amended in 1995 and associated Code was carried out from 2006 to 2010. These amendments will have a certain degree of impact on Maritime Education and Training(MET) institutes in terms of education and training of seafarer worldwide. Particularly, the Far East region countries are effected more than other regions since they covered about 30% of officers and 37% ratings in the world. In view of these facts this dissertation conceived to analyze the problems in the Far East main seafarer supply countries faced the implementation of "STCW Manila Amendments" To analyze these problems, this dissertation carried out questionnaire research to 7 targeted main MET of major Far East seafarer supply countries. After research this dissertation suggests the possible solutions such as, Joint On-Board Training Center; Joint Asia Maritime E-learning Systems; methods to reducing work-load, ship inspection burden and determine mandatory minimum safety manning standards in a safe way; technical cooperation fund to installation of training equipment; and clarify vague terminology of STCW Manila Amendments, to solve problems identified through the questionnaires.

• Journal of Korean Foot and Ankle Society
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• v.22 no.1
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• pp.8-15
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• 2018

Ankle osteoarthritis is a debilitating condition that causes severe pain associated with functional impairment and decreased activity. Ankle osteoarthritis, unlike that of the knee or hip joint, is rare in primary arthritis. Most cases are traumatic arthritis that occur after ankle sprain or fractures or chronic ankle instability. Although ankle fusion has been regarded as the standard treatment of ankle osteoarthritis in the past, total ankle arthroplasty (TAA) is increasing due to the development of the implant design and surgical techniques. TAA is biomechanically superior to ankle fusion by preserving the movement of the ankle joint. In particular, it is functionally superior to ankle fusion because it enables normal joint motion during gait. In addition, there is an advantage of preserving the movement of the hindfoot and reducing the abnormal stress applied to the adjacent joints after ankle fusion to prevent the occurrence of long-term adjacent joint arthritis. Although the short-term and mid-term results of TAA have been reported to be excellent, long-term follow-up has a relatively low survival rate and high complication rate compared to total knee or hip arthroplasty. Therefore, continuous and further research is needed.

• Tribology and Lubricants
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• v.28 no.6
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• pp.328-332
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• 2012

Generated Axial Force (GAF) due to internal friction at Constant Velocity (CV) joints is one of the causes generating vibration problems such as shudder in vehicle. In this study, the GAF measuring tester is developed to precisely measure GAF caused by internal friction in CV joints. As the developed tester can control temperature at joint, driving torque, angle of rotation and joint angles, actual driving conditions such as sudden acceleration can be applied to the machine. GAFs are measured and compared by using different types of grease in tripod housing. Also GAFs are measured for both new and used CV joints to be compared and analyzed. The test result shows the repeatability and consistency of the tester in terms of the different test conditions. By using the developed CV joint tester, friction performance of the joint can be evaluated by proposing the best CV joints as well as greases generating the lowest GAF.