• The Journal of Advanced Prosthodontics
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• 제6권6호
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• pp.491-497
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• 2014

PURPOSE. This study evaluated the influence of abutment materials on the stability of the implant-abutment joint in internal conical connection type implant systems. MATERIALS AND METHODS. Internal conical connection type implants, cement-retained abutments, and tungsten carbide-coated abutment screws were used. The abutments were fabricated with commercially pure grade 3 titanium (group T3), commercially pure grade 4 titanium (group T4), or Ti-6Al-4V (group TA) (n=5, each). In order to assess the amount of settlement after abutment fixation, a 30-Ncm tightening torque was applied, then the change in length before and after tightening the abutment screw was measured, and the preload exerted was recorded. The compressive bending strength was measured under the ISO14801 conditions. In order to determine whether there were significant changes in settlement, preload, and compressive bending strength before and after abutment fixation depending on abutment materials, one-way ANOVA and Tukey's HSD post-hoc test was performed. RESULTS. Group TA exhibited the smallest mean change in the combined length of the implant and abutment before and after fixation, and no difference was observed between groups T3 and T4 (P>.05). Group TA exhibited the highest preload and compressive bending strength values, followed by T4, then T3 (P<.001). CONCLUSION. The abutment material can influence the stability of the interface in internal conical connection type implant systems. The strength of the abutment material was inversely correlated with settlement, and positively correlated with compressive bending strength. Preload was inversely proportional to the frictional coefficient of the abutment material.

• The Journal of Advanced Prosthodontics
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• 제11권6호
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• pp.350-357
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• 2019

PURPOSE. This study aims to evaluate the loosening torque on the implant fixture, and to assess the accuracy of difference electronic torque drivers. MATERIALS AND METHODS. Three electronic torque drivers were used to measure the loosening torque on the implant system (AnyOne; MegaGen). The implant fixtures were divided among the 3 electronic torque driver types (W&H, SAESHIN, and NSK group) and 9 for each group. The screws were fastened at the implant fixture by three electronic torque drivers using the tightening torques recommended by the manufacturers of the drivers. After 10 minutes, the screws were again fastened at the implant fixture with equal torque. Then, the loosening torques were measured with an MGT12 torque gauge (MARK-10, Inc.). This measurement procedure was repeated 10 times under loosening torques of 15 Ncm, 25 Ncm, and 35 Ncm. In the statistical analysis, all values of loosening torque were analyzed with the one-way ANOVA and Kruskal-Wallis test (α=.05) for comparative evaluation. RESULTS. There were significant inter-group differences at loosening torques of 15 Ncm and 25 Ncm (P<.05). The accuracy of the NSK driver was the highest, followed by SAESHIN and W&H. There was no significant difference between NSK and W&H at 35 Ncm (P>.05). The SAESHIN driver showed the closest loosening torque at 35 Ncm. CONCLUSION. The most accurate loosening torques were SAESHIN at 35 Ncm, and NSK at 15 Ncm and 25 Ncm. Since the loosening torque may vary depending on the tightening torques and electronic torque drivers, periodic calibration of the electronic torque driver is recommended.

• 한국구조물진단유지관리공학회 논문집
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• 제10권2호
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• pp.165-176
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• 2006

본 연구는 볼트의 조임력을 이용한 와이어로프의 휨보강 효과에 대한 실험 및 사례에 대한 것이다. 본 공법은 와이어로프에 볼트와 너트를 이용해 긴장응력을 도입하며, 이 방법은 시공성이 매우 우수하다. 제안된 방법에 대한 휨보강 효과에 대한 검증을 위해 실험을 수행하였다. 콘크리트 압축강도는 24MPa이고 전단스팬비(a/d)가 2.8인 실험체의 주요변수로는 초기 긴장응력과 새들 수량으로 하였다. 실험결과, 무보강 실험체에 비해서 휨내력은 약 160% 증가하였으며, 초기 긴장력에 따라서 균열 및 극한모멘트가 증가하였다. 그러나 새들의 수량은 균열 및 극한모멘트에는 영향을 주지 않았다. 실제 구조물의 보강공사에 적용한 사례를 통해서 제안된 공법은 다른 보강방법보다 매우 경쟁력 있는 방법임을 알 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3335-3340
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• 2007

The government have been tightening EM regulation gradually but the effect is not good because of rapid increase of vehicles. And medium & heavy duty diesel vehicles, even though the number is small, exhaust very large pollutants(about over 50%). Especially it is more severe about old trucks and buses. Accordingly, CNG vehicle and the retrofit of diesel to CNG must be an alternative in order to protect the atmospheric environment and improve the air quality in the metropolitan area. The main object of this study is to secure the retrofit technology of diesel to CNG vehicle and the management system of CNG engine. we passed the government emission certification test. In addition to this, the mass production for retrofit is also studied. Results of emission and durability test for certification are as follows; there was no problem during 30,000km vehicle durability test and good emission levels satisfying the regulation.

• Steel and Composite Structures
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• 제22권1호
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• pp.45-61
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• 2016

The domestic and foreign scholars conducted many studies on mechanical properties of wave web steel beam and high-strength spiral stirrups confined concrete columns. Based on the previous research work, studies were conducted on the anti-seismic property of the end plate bolt connected wave web steel beam and high-strength spiral stirrups confined concrete column nodes applied with pre-tightening force. Four full-size node test models in two groups were designed for low-cycle repeated loading quasi-static test. Through observation of the stress, distortion, failure process and failure mode of node models, analysis was made on its load-carrying capacity, deformation performance and energy dissipation capacity, and the reliability of the new node was verified. The results showed that: under action of the beam-end stiffener, the plastic hinges on the end of wave web steel beam are displaced outward and played its role of energy dissipation capacity. The study results provided reliable theoretical basis for the engineering application of the new types of nodes.

• 산업경영시스템학회지
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• 제31권4호
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• pp.153-161
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• 2008

신뢰성 평가 시험은 종종 성능 평가에 장기간의 시간이 요구되며, 전체 생산비용까지 증가시키는 문제점을 안고 있다 스트레스를 이용한 가속수명시험은 제품의 신뢰성 고장과 밀접한 관련이 있는 고장 메커니즘의 촉진을 통해 고장에 이르는 기간을 단축함으로써 신뢰성 평가의 효율성을 도모할 수 있다. 본 연구에서는 이러한 스트레스 가속 시험에 빈도가속(Usage-Rate Acceleration) 또는 판정가속(Tightening Critical-Values) 등을 결합하여 한층 높은 가속효과를 도모하는 방법을 제안하고, 국내에서 생산되고 있는 2차 전지 제품에 대한 실제 시험 사례분석을 통해 결합된 가속방법의 효과를 실증적으로 보여주고 있다.

• 한국기계가공학회지
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• 제20권5호
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• pp.103-110
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• 2021

The mounting performance of the GFRP(Glass fiber Reinforced Plastic) beam and the mechanical mounting of the steel bracket was studied to be mounted as a GFRP impact beam on the side door of the passenger car. Moreover, an open-hole tensile test was performed to evaluate breakage tendency based on GFRP stacking conditions. Furthermore, the tightening strength of rivets and bolts was compared using the single lap-shear tension test for the GFRP stacking pattern. Additionally, the GFRP beam and bracket mounting features were designed; moreover, the prototype and bracket were assembled. Additionally, the bracket mounting bending test and the door assembly static bending test were performed to verify the stability of the bracket mounting. In the bracket fastening bending test, no breakage occurred in the connection part between the GFRP beam and the bracket, and it showed 67% (24.4 kN) improved performance compared to steel. In the static bending test of the door assembly, the initial average reaction force increased by 25% compared to the steel, and the performance of all FMVSS-214 regulations was satisfied. The replacement of GFRP impact beams resulted in a 30% weight reduction

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2860-2865
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• 2011

Recently, the number of passengers using urban railway has been increased by reasons of the reductions of car use due to high fuel prices and the enlightenment about the environment. Above all, the noise and the vibration coming from the friction between the wheel and the rail of trains in operation which is not only a factor that hinders riding comforts but causes civil complaints. Furthermore, the noise has become social issues from tightening the relevant regulations by the government since January 2010. Although ballasted tracks were constructed on urban railways at the time of opening, they have been changed into slab tracks because slab tracks require much less maintenance. However, in view of sound absorptivity of track, slab tracks have 10 times less capability than ballasted tracks(ballasted track : 0.5~0.6/slab tracks : 0.06) results more noise than that of ballasted tracks as much as 3dB(A) since slab tracks emit more reflection noise. Therefore, in order to minimize reflection noise on slab tracks, noise abatement system has been developed as a national R&D program to apply on-site test. It is assumed that the construction technology developed in this study can be used not only as basic data for the on-site test for the noise reduction in urban railway but as an efficient construction method.

• Structural Engineering and Mechanics
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• 제45권3호
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• pp.337-354
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• 2013

For shield TBM (Tunnel Boring Machine) tunnel lining, the segment joint is the most critical component for determining the mechanical response of the complete lining ring. To investigate the mechanical behavior of the segment joint in a water conveyance tunnel, which is different from the vehicle tunnel because of the external loads and the high internal water pressure during the tunnel's service life, full-scale joint tests were conducted. The main advantage of the joint tests over previous ones was the definiteness of the loads applied to the joints using a unique testing facility and the acquisition of the mechanical behavior of actual joints. Furthermore, based on the test results and the theoretical analysis, a mechanical model of segment joints has been proposed, which consists of all important influencing factors, including the elastic-plastic behavior of concrete, the pre-tightening force of the bolts and the deformations of all joint components, i.e., concrete blocks, bolts and cast iron panels. Finally, the proposed mechanical model of segment joints has been verified by the aforementioned full-scale joint tests.

• 패션비즈니스
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• 제9권3호
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• pp.88-98
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• 2005

This study focuses on the needs at both consumers and manufacturers. It aims to find ways for consumers to purchase outfits that would fit their particular body type and preferences at reasonable prices, choose raw materials and style at garments, and virtually try them on. In addition, the study is designed to help apparel manufacturers identity customers' changing needs, reduce inventories, manage information on customers' body type in a digitalized form, and eventually contribute to promoting electronic commerce. Based on nine basic patterns that tit each subject, 108 virtual garments are created by adjusting the size of the patterns (9 subjects $\times$ 4 body parts $\times$ 3 patterns = 108 outfits). In order to determine fitting preferences for each body part and find optimized conditions, cross-tabulation analysis including $X^2$ and frequency analysis were performed to measure the appearance rate. A style of virtual garment, which is minus 2cm from chest size was chosen as the most appropriate pattern to the baseline location of front the chest. For the waist parts, the C style as an appropriate virtual garment to front and back view. In the front, lateral and back view, a style was chosen in the response to the sleeve-bodice combinations, the ease amount of armhole area, the armhole depth and the loosening of tightening or armhole line.