• Proceedings of the KWS Conference
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• 2007.11a
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• pp.158-160
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• 2007

The butt and lap configurational friction stir welding of type 304 stainless steel was conducted in this study. The sound joints were obtained by WC tool. As the welding distance increased, tool deformation gradually increased at the pin edge. The discoloration by oxidation was observed at the top surface of the joint, a sufficient heat-input was required to avoid the welding defect owing to the lack of stirring at the welding start point. Very fine grains were observed in the stir zone, and the grain coarsening was not observed in the heat affected zone.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.143-146
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• 2005

In modern automotive control modules, mechanical failures of surface mounted electronic components such as microprocessors, crystals, capacitors, transformers, inductors, and ball grid array packages, etc., are mai or roadblocks to design cycle time and product reliability. This paper presents a general methodology of failure analysis and fatigue prediction of these electronic components under automotive vibration environments. Mechanical performance of these packages is studied through finite element modeling approach fur given vibration environments in automotive application. Using the results of vibration simulation, fatigue lift is predicted based on cumulative damage analysis and material durability information. Detailed model of solder/lead joints is built to correlate the system level model and obtain solder strains/stresses. The primary focus in this paper is on surface-mount interconnect fatigue failures and the critical component selected for this analysis is 80 pin plastic leaded microprocessor.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.30.3-30
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• 2001

In this paper, we designed the 6-wheeled mobile robot (6-WMR) with the passive linkage mechanism which enables 6-WMR to passively adapt to the given stairs. To overcome the limit of adaptability to the terrain of conventional WMR and improve the energy efficiency, we proposed the new WMR using the passive linkage mechanism. The passive linkage mechanism consists of the simple four-bar linkage mechanism which allows 6-WMR to climb stairs with adaptability and an additional link which is connected to the four-bar linkage mechanism by a pin-slot joint to enable 6-WMR to passively go up the stairs. We made a miniature model of the proposed 6-WMR ...

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.38-39
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• 2021

The use of temporary container classrooms has increased in recent years due to the development of the construction industry and renovation or rehabilitation of schools. Therefore, various problems, such as errors during assembling, design and insulation issues, and noise problems, have surfaced during the construction of temporary container classrooms. This study analyzes the causes of assembly errors during the manufacturing and installation processes to improve the quality of temporary container classrooms. Assembly errors are caused by non-level planes and inaccurate cutting during the manufacturing process. In the installation process, poor leveling is a major factor that causes errors during the assembly of temporary container classrooms. These causes result in uneven horizontal or vertical planes and uneven height. To solve these problems, quality improvement measures, such as pin connection, jig, joint coupling, and surface plates are proposed in this study.

• Journal of Korean Foot and Ankle Society
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• v.9 no.2
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• pp.140-145
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• 2005

Purpose: To analyze the outcome of metatarsal lengthening of first brachymetatarsia by callotasis using an external fixator. Materials and Methods: Between January 1998 and February 2004, 10 patients (17 cases) were reviewed. The mean age at operation was 17.3 years. Seven patients had bilateral first brachymetatarsia and eight patients had combined 4th brachymetatarsia. The operations were performed with a monoexternal fixator, and distraction was started at a rate of 0.75 mm/day after 7 days. The radiographic results were evaluated by lengthening amount and percentage, fixation time, and healing index. Complications and AOFAS score were evaluated. Results: The average lengthening amount was 17.7 mm and the average lengthening percentage was 43.4%. The external fixation time was 107 days and average healing index was 69.8 days/cm. The evaluation according to AOFAS score was excellent in 12 cases and good in 5 cases. Complications were 4 cases of hallux valgus, 4 of metatarsophalangeal joint stiffness, 3 of medial angular deformity, 3 of pes cavus, 2 of pin breakage, 2 of pin site infection, and 1 of skin hyperpigmentation. Conclusion: Callotasis for 1st brachymetatarsia is a very useful treatment method with high patient satisfaction, excellent healing rate and early ambulation without bone graft. Nevertheless, great care must be taken to minimize the various possible complications.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.3
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• pp.1-9
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• 1998

The exhaustion of fossil fuels and serious environmental pollution put the concern about non-po llution energy into the world. On the developments of technology, wind energy has been spotlighted as a non-pollution energy in many countries. This study has carried out the aerodynamic and structural design procedure of the lightweight composite rotor blades with an appropriate aerodynamic performance and structural strength for the 500㎾ medium class wind turbine system. The previous design, which is shell-spar structure, is redesigned to shell-spar- sandwich structure for light weight. Large deformation problem from light weight is examined by non-linear analysis. Local buckling occurred under lower stress than failure stress. The buckling analysis is accomplished to confirm the safety of the composite blade. The stress analysis around pin hole joint part at hub is carried out and it is confirmed that the pin hole is not failed. The results show that the resonance of redesigned blade does not happen in operation range.

• Journal of the Korean Orthopaedic Association
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• v.56 no.4
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• pp.361-365
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• 2021

Pelvic fractures are high-energy injuries, often accompanied by damage to the adjacent tissues and organs. For patients with pelvic trauma, active treatment is required early in the injury, because mortality can increase if appropriate treatment is not provided. In most cases, however, minimally invasive surgery is considered because extensive surgery cannot be performed due to the patient's condition. Percutaneous fixation of the pubis has been introduced because it can be applied easily to achieve the stability of the anterior part of the pelvis. Although many studies introduced percutaneous fixation of pubic bone fractures, most describe screw fixation for nondisplaced fractures. When treating displaced fractures with percutaneous screw fixation, it is difficult for the guide pin or drill bit to avoid the joint surface. Using a bent guide pin could allow easy insertion of the cannulated screw while avoiding the articular surface.

• Journal of the Korea Institute of Building Construction
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• v.22 no.5
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• pp.519-530
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• 2022

As online commerce increases, the construction of large logistics buildings worldwide is exploding. Most of these buildings have the characteristics of long span and heavy loaded and use precast concrete components, a pin joint structure, for rapid construction. However, due to construction safety and structural stability requirements, the pin joint structure has many limitations in terms of the erection of the PC member, which increases the time and cost. A structural frame connected with steel joints between precast concrete components, called a SMART frame, has been developed, which addresses these constraints and risks. However, the effect of the appllication of a SMART frame on the time aspect has not been analysed. The study is a time reduction effect analysis of a SMART frame for long span and heavy loaded logistics buildings. For this study, the authors select a case site erected using existing PC components, and compare the time reduction with the SMART frame erection simulations. Through this analysis, it was found that a time reduciton about 4 months, approximately 48% of the conventional PC installation period could be achieved. If the SMART frame is applied when carrying out future large-scale logistics building projects, it can be expected to have the effect of significantly shortening the construction period compared to the conventional method.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.40-47
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• 2016

Instead of metal connector generally used on the structural glued laminated timber rahmen joints, the GFRP reinforced laminated plates combining veneer and GFRP (Glass Fiber Reinforced Plastic) and bonded type GFRP rod were used as the connectors. As a result of moment resistance performance evaluation on the joint part applied with these connectors, the yield moment of specimen using the GFRP reinforced laminated plates and GFRP rod pin was measured 4 % lower in comparison to the specimen (Type-1) using the metal connectors, but the initial rotational stiffness was measured 29% higher. Also, the yield moment and rotational stiffness of the specimen using the GFRP-reinforced laminated plates and wood (Eucalyptus marginata) pin showed were measured 11% and 56% higher in comparison to the Type-1 specimen, showing the best performance. It was also confirmed through the failure shape and perfect elasto-plasticity analysis that it showed ductility behavior, not brittle fracture, from the shear resisting force by the pin and the bonding strength increased and the unification of member was carried out. On the other hand, in case of the specimen bonded with GFRP rod, it was impossible to measure the bonding performance or it was measured very low due to poor bonding.

• Corrosion Science and Technology
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• v.17 no.2
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• pp.68-73
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• 2018

Substitution of hip and knee joints by CoCr alloys is in great demand due to their high wear resistance and good biocompatibility. Understanding of tribocorrosion in joint replacements requires study of variables such as coefficient of friction and the choice of a proper corrosive medium in wear-corrosion tests carried out in the lab. The objective of this study was to characterize tribocorrosion behaviour of CoCr alloy with low (LCCoCr) and high carbon (HCCoCr) contents in several corrosive media: NaCl, Phosphate Buffer Solution (PBS), and PBS with hyaluronic acid (PBS-HA). Tribocorrosion tests were carried out on a pin-on-disk tribometer with an integrated electrochemical cell. A normal load of 5N was applied on the alumina ball counterpart at a rotation rate of 120 rpm. Coefficient of friction (COF) was measured and tribocorrosion behaviour was characterized by in situ application of electrochemical techniques. HCCoCr alloy immersed in PBS-HA showed the best tribocorrosion behaviour with the lowest COF. In this case, in situ measurement of corrosion potential and the impedance data under wear corrosion process showed an active state while passive film was continuously destroyed without possibility of regeneration.