• Journal of the Ergonomics Society of Korea
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• v.25 no.1
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• pp.1-6
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• 2006

The effectivenes of the opener has also been evaluated. The developed opener increased the torque capability of the wrist by 3.2 times so that most of the elderly can open screw caps. In this study the range of the screw cap sizes tested were between 22.0~ 32.0m, which covers over 92.0% of the screw caps in the market that are difficult to open. This particular screw cap opener developed in this study applies to the aged asstrength.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.129-137
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• 2010

The purpose of this document is to introduce the localized development procedure for socket head cap screw used for satellite application. For localized development and verification of socket head cap screws, manufacturing process was composed of head forming, heat treatment, rolling process and surface treatment to meet aerospace hardware requirements based on MIL-B-7838, ECSS-Q-70-46A and KS W 8168 aerospace specification. In order to verify the quality and performance of localized screw, several kinds of qualification tests are successfully completed. By comparing the quality and performance for the localized screws and the same size oversea-procured screws, we can sure that localized socket head cap screws have good quality performance enough to use for aerospace application.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.03a
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• pp.159-172
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• 1998

• The monthly packaging world
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• s.209
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• pp.101-105
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• 2010

• Journal of Korean Society of Steel Construction
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• v.25 no.5
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• pp.543-553
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• 2013

As the deep deck plate has the shape of open cross section, It can cause structural problems such as bending torsions due to instability of the section. There are a number of fasteners types which are frequently used on light gage steel diaphragms such as bolts, rivets, welds, and screws. In this study, the structural capacity of the self drilling screw connection between the deep deck and the reinforced cap plate was evaluated by experimental variables such as the arrangement method, numbers of screw, pitch of screw, and head plate thickness.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.12
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• pp.979-984
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• 2016

Recently, ball screws have been used in machine tools, robot parts, and medical instruments. The demand for ball screws of high precision and reduced size is increasing because of the growth of high value-added industries. Three types of ball screws are typically used: deflector type, end-cap type, and tube type. They are also classified from C0 to C9 according to the precision level. A deflector type ball screw can reduce the variation of rotational torque and the size of the nut of the ball screw is minimized. To ensure the reliable design of ball screws, it is important to perform a structural analysis. The purpose of this study is to perform a stability evaluation through analysis of a deflector type miniature ball screw for weapon systems. The analysis is performed through Finite Elements Method (FEM) simulation to predict characteristics such as deformation, stress, and thermal effects. The interference between the shaft and the deflector for smooth rotation are also studied. Based on the results of the analysis, the development of the deflector type miniature ball screw for weapon systems is performed.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.6
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• pp.561-568
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• 2008

STATEMENT OF PROBLEM: Currently, many implant systems are developed and divided into two types according to their joint connection: external or internal connection. Regardless of the connection type, screw loosening is the biggest problem in implant-supported restoration. PURPOSE: The purpose of this study is to assess the difference in stability of abutment screws between the external and internal hexagonal connection types under cyclic loading. MATERIAL AND METHODS: Each of the 15 samples of external implants and internal abutments were tightened to 30 N/cm with a digital torque gauge, and cemented with a hemispherical metal cap. Each unit was then mounted in a $30^{\circ}$ inclined jig. Then each group was divided into 2 sub-groups based on different periods of cyclic loading with the loading machine (30 N/ cm - 300 N/cm,14 Hz: first group $1{\times}10^6$, $5{\times}10^6$ cyclic loading; second group $3{\times}10^6$, $3{\times}10^6$ for a total cyclic loading of $6{\times}10^6$) The removal torque value of the screw before and after cyclic loading was checked. SPSS statistical software for Windows was used for statistical analysis. Group means were calculated and compared by ANOVA, independent t-test, and paired t-test with ${\alpha}$=0.05. RESULTS: In the external hexagonal connection, the difference between the removal torque value of the abutment screw before loading, the value after $1{\tims}10^6$ cyclic loading, and the value after $1{\times}10^6$, and additional $5{\times}10^6$ cyclic loading was not significant. The difference between the removal torque value after $3{\times}10^6$ cyclic loading and after $3{\times}10^6$, and additional $3{\times}10^6$ cyclic loading was not significant. In the internal hexagonal connection, the difference between the removal torque value before loading and the value after $1{\times}10^6$ cyclic loading was not significant, but the value after $1{\times}10^6$, and additional $5{\times}10^6$ cyclic loading was reduced and the difference was significant (P < .05). In addition, in the internal hexagonal connection, the difference between the removal torque value after $3{\times}10^6$ cyclic loading and the value after $3{\times}10^6$, and additional $3{\times}10^6$ cyclic loading was not significant. CONCLUSION: The external hexagonal connection was more stable than the internal hexagonal connection after $1{\times}10^6$, and additional $5{\times}10^6$ cyclic loading (t = 10.834, P < .001). There was no significant difference between the two systems after $3{\times}10^6$, and additional $3{\times}10^6$ cycles.

• Journal of the Korean Geotechnical Society
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• v.24 no.8
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• pp.25-34
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• 2008

A new hybrid oedometer cell is designed and manufactured to investigate a behavior of soft soils by using elastic and electromagnetic waves during consolidation test. Bender elements, which generate and detect shear waves, are placed in the top cap and the bottom plate and mounted on the oedometer wall. Double wedge type electrical resistance probe, which measures local void ratio change, is positioned onto the top cap of the oedometer cell. The bender elements and the electrical resistance probe are anchored into a nylon set screw with epoxy resin. The nylon set screw with epoxy resin minimizes directly transmited elastic waves through the oedometer cell due to impedence mismatch and allows for easy replacement of defected bender elements and electrical resistance probe. Primary consolidation time can be estimated from the slope of electrical resistance versus log time curve and the evolution of shear wave velocity. The shear wave velocity can be used to assess inherent anisotropy when disturbance effects are minimized because particle alignment affects the shear wave velocity. The void ratios evaluated by the electrical resistance probe are similar to those by the settlement during consolidation. This study suggests that the shear wave velocity and the electrical resistance can provide complementary imformations to understand consolidation characteristics such as primary consolidation, anisotropy, and void ratio.

• Fire Science and Engineering
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• v.22 no.4
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• pp.54-60
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• 2008

In this study, damage characteristics of MCCB and terminal block due to poor contact were analyzed, and various poor contact detection techniques were suggested. Firstly, the detection techniques using thermocouple and infrared thermal camera were analyzed respectively. Also, thermo-cap during poor contact detected abnormal status effectively by changing its color, and the detection system using an odor detector and odor capsules was analyzed. Lastly, poor contact detection screw was made using characteristics of fusible alloy, and we applied the poor contact detection screw to terminal block. The above methods could prevent electrical fire caused by poor contact effectively if they are used properly.

• Journal of Power System Engineering
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• v.15 no.4
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• pp.19-24
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• 2011

The operational efficiency of domestic gas turbine is about 25% and it is now in the trend of the gradual growth in spite of the severe temperature, frequent starting and shutdown according to the environmental management and the energy-efficient use. Rotor bolts of gas turbine in power plants have been the cause of defects because these gas turbines have been operated for a long time under the high pressure and temperature environment experiencing the aging change and stress concentration of the bonded part. The connection parts of the bolt revealed various failure shape and these parts were elongated under very low pressure when operated in the relaxed condition. The cause is in the lack of the metal distribution in the bottle lack area and the cap screw of the bolt is broken totally in case that the nut is fastened in most cases. Gas turbine rotor bolts are connected to the rotor wheel and these bolts caused the vibration, the bulk accident of the rotor in the event that the coupling power among these bolts was relaxed. Therefore, we would like to evaluate the soundness of the main part of the gas turbine rotor bolt through the measurement of the inner condition change along with the mechanic deterioration and temperature, stress in the gas turbine rotor material.