• Journal of Welding and Joining
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• 제19권2호
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• pp.98-103
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• 2001

Root gap out of standard by welding deformation is frequently produced at butt weld joints of steel bridge. For example although standard root gap is below 6mm at butt weld joints of plates under 15mm thickness. maximum 35mm root opening is produced at the weld field. At this case, the part out of standard is generally built up and the rest part is welded by WPS. Direct welding without built-up welding is preferred in weld field because built-up welding process bring about the cost-up at manufacturing. To apply this direct weld to root gap out of standard, the investigation about mechanical properties and fatigue at weldment is required. Inthisstudy, therefore the verification for direct weld without built up is performed at weldment as root gap. It includes tension, bending. hardness, impact and fatigue test for each welding specimen of 6mm, 25mm, 35mm root gap.

• 한국철도학회논문집
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• 제20권2호
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• pp.173-181
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• 2017

장애물제거기는 선로 내 장애물에 의한 충돌사고 발생 시 장애물을 선로 밖으로 밀어내거나 에너지흡수부재를 통해 충돌에너지를 흡수하여 열차 탈선을 방지하고 충돌사고에 의한 피해를 최소화하기 위한 장치이다. 본 연구에서는 인장형 에너지흡수부재와 4절 링크를 이용하여 장애물제거기의 작동 메커니즘을 구성하여 장애물제거기를 설계하였다. 또한 EN 15227에서 요구하는 정적강도 및 에너지흡수조건을 확인하기 위한 성능검증시험 방법을 고안한 뒤 유한요소해석 및 UTM (Universal Test Machine)을 이용한 성능검증시험을 수행하였다. 본 연구를 통해 EN 15227의 요구조건을 만족하는 장애물제거기를 개발하였으며, 제안된 장애물제거기의 설계 및 검증 절차에 따라 붕괴하중의 조절이 가능하며 이를 실험을 통해 검증할 수 있는 방법을 제안하였다.

• 전기학회논문지
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• 제65권9호
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• pp.1590-1596
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• 2016

In this paper, catenary wires were analyzed aging through the experiment about a new product and a test sample in accordance with temperature changes from long-term use. In case of the contact wire, the maximum load was reduced within 7% and the tensile strength showed a reduced within 6.7% compared with a new reference standard $110mm^2$. 19 Strands of messenger wire have a little more than a standard value, but result data on tensile test were less than the reference value about stranded wire. Also parts among 49 strands of dropper was found to be smaller than the reference value and it appeared greatly increasing intensity as toward the center of the strand.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.237-241
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• 1998

This study is concerned with the optimum blank design which is able to minimize earing phenomena. A new analytic method is proposed to determine the optimum blank shape only using the tension test and standard deep drawing tests. Introducing a dimensionless parameter related to the earing and using a Fourier analysis, the optimum blank shape can be obtained by R-value and the tested results. The theoretical results by the proposed method are good agreement with the experimental results through several deep drawing tests using steel as working materials.

• 한국산학기술학회논문지
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• 제19권11호
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• pp.350-356
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• 2018

팬터그래프(Pantograph)와 전차선간의 동적 상호작용인 접촉력(contact force)은 차량에 대한 안정적 전원공급 특성인 집전성능을 평가하는 중요한 지표이다. 본 연구에서는 동력분산형 고속열차 시험차량인 HEMU-430X(High-speed Electric Multiple Unit - 430km/h eXperiment) 차량의 팬터그래프 동적 접촉력 특성을 전차선 장력에 따라 분석하였고, 이를 팬터그래프-전차선 동적 상호작용 모델을 이용한 해석결과와 비교하였다. 시험결과와 해석결과를 비교한 결과, 주요 동적접촉력 특성인 평균접촉력 및 접촉력 표준편차가 비교적 잘 일치하는 것을 확인하였다. 또한 해석모델을 이용하여 전차선 장력과 접촉력과의 상관관계를 차량 운행속도에 따라 제시하였으며, 이를 이용하여 각 운영속도별 최적 전차선 장력을 제시하였고 이를 국제규격과 비교하였다. 그 결과 해석을 통해 도출된 결과와 국제 규격에서 권장하는 전차선 장력이 비교적 잘 일치하는 것을 알 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제39권5호
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• pp.429-436
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• 2011

The selected physical and mechanical properties of non-certificated LVL circulated in domestic lumber market were investigated and compared to relevant standards. The tested LVL passed the moisture content and the soaking delamination rate limit as per domestic (KS) and Japanese standard (JAS). The evaluated mechanical properties were flatwise/edgewise bending strength, modulus of elasticity (MOE), horizontal shear and compressive strength. The 30 mm-thick LVL showed significantly higher bending strength than that of the 25 mm-thick LVL. The modulus of elasticity (MOE) showed same tendency in the results of bending strength. The edgewise bending strength and MOE were higher than that of flatwise bending strength and MOE. The horizontal shear strength values were also showed similar results to bending strength values. The tested results were compared each other and each products were graded according to JAS 701 grade specification. The failure mode of LVL in bending test showed the similar failure mode of solidwood that failed in a simple tension manner (splintery tension). The glue line failure was severe in 25 mm-thick specimens due to concentration of shear stress in layer discontinuity containing small voids and starved glue lines. In horizontal shear strength test, failure mode of LVL showed the typical horizontal shear failure. Compressive specimens failed with fiber crushing in company with apparent delamination that splitted along the length of the specimens. From the results, the complete bonding between lamination and consistency in thin veneer layer were considered as a critical factor in the mechanical properties of LVL. Moreover, the standard test procedure and specification for non-certificated LVL should be required to check the performance of uncertificated materials.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.512-517
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• 2003

The repeated loading responses of four shear-critical reinforced concrete beams, with two different shear span-to-depth ratios, were studied. One series of beams was reinforced using pairs of bundled stirrups with $90^{\circ}C$ standard hooks, having free end extensions of $6d_b$. The companion beams contained shear reinforcement made with larger diameter headed bars anchored with 50mm diameter circular heads. A single headed bar had the same area as a pair of bundled stirrups and hence the two series were comparable. The test results indicate that beams containing headed bar stirrups have a superior performance to companion beams containing bundled standard stirrups, with improved ductility, larger energy adsorption and enhanced post-peak load carrying capability. Due to splitting of the concrete cover and local crushing, the hooks of the standard stirrups opened, resulting in loss of anchorage. In contrast, the headed bar stirrups did not lose their anchorage and hence were able to develop strain hardening and also served to delay buckling of the flexural compression steel. Excellent load-deflection predictions were obtained by reducing the tension stiffening to account for repeated load effects.

• Steel and Composite Structures
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• 제15권6호
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• pp.659-677
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• 2013

This paper introduces new specimens of Steel-Carbon Fibre Reinforced Polymer composite developed in accordance with standard test method and definition for mechanical testing of steel (ASTM-A370). The main purpose of this research is to study the behaviour of steel-CFRP composite specimen under uniaxial tension to use it in beams in lieu of traditional steel bar reinforcement. Eighteen specimens were prepared and divided into six groups, depending upon the number of the layers of CFRP. Uniaxial tensile tests were conducted to determine yield strength and ultimate strength of specimens. Test results showed that the stress-strain curve of the composite specimen was bilinear prior to the fracture of CFRP laminate. The tested composite specimens displayed a large difference in strength with remarkable ductility. The ultimate load for Steel-Carbon Fibre Reinforced Polymer composite specimens was found using the model proposed by Wu et al. (2010) and nonlinear FE analysis. The ultimate loads obtained from FE analysis are found to be in good agreement with experimental ones. However, ultimate loads obtained applying Wu model are significantly different from experimental/FE ones. This suggested modification of Wu model. Modified Wu's model which gives a better estimate for the ultimate load of Steel-Carbon Fibre Reinforced Polymer (SCFRP) composite specimen is presented in this paper.

• Journal of the Korean Wood Science and Technology
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• 제26권1호
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• pp.14-18
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• 1998

A low density polyethylene(LDPE) was examined as an additive in phenol-formaldehyde(PF) resin adhesive for bonding radiata pine plywood. The LDPE was supplied by the commercial manufacturer. The LDPE was compared to a commercial filler commonly used in structural plywood adhesives in the United States. The adhesive mixes were made by following the recommended procedure of Georgia-Pacific Resins Inc.. using plywood-type PF resin. A total of 48 three-ply plywoods. 6.3 mm nominal thickness and 30 by 30 em in size, were made at two press times (4 and 5 min). two press temperatures (150 and $160^{\circ}C$) and 30 minute assembly times for four adhesive mixing types. Evaluations of the LDPE addition were carried out by performance tension shear tests after two cycle boil aging tests on plywood per the U.S. Product Standard PS I-83. After accelerated-aging tests. plywoods were exhibited no delamination. The test results included tension shear strength and estimated wood failure values. The plywood test results support the use of polyethylene as an additive in plywood adhesives.

• 한국구조물진단유지관리공학회 논문집
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• 제3권3호
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• pp.139-147
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• 1999

Six reinforced concrete shear wall, constructured with fully rigid, slit, and infilled types, were tested under both vertical and cyclic loadings. Experimental programs were carried out to evaluate the seismic performance of such test specimens, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility, under load reversals. All the specimens were modeled in one-third scale size. Based on the test results, the following conclusions can be made. For the diagonal reinforced slit and infilled shear wall specimens, it was found that the failure mode shows very effective crack control and crushing due to slippage prevention of boundary region and reduction of diagonal tension rathar than the brittle shear and diagonal tension failure. The ductility of specimens designed by the diagonal reinforcement for the slit and infilled shear wall was increased 1.72~1.81 times in comparison with the fully rigid shear wall frame. Maximum horizontal load-carrying capacity of specimens designed by the diagonal reinforcement ratio the slit and infilled shear wall was increased respectively by l.14 times and l.49 times in comparison with the standard fully rigid shear wall frame.