• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 추계학술대회논문집
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• pp.84-88
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• 1997

The Jonhnson-Cook constitutive relation has been used in dynamic plasticities. The constants of the Jonhson-Cook relation of sheet metals for an autobody is not known yet. In this paper, the material properties of SPCEN, SPCC and SPRC in the high strain rate states have been acquired. A new tension split Hopkinson bar was used in high speed tensile tests of sheet metals. The experimental results acquired from the apparatus are used to determine the constants of Johnson-Cook constitutive relation of sheet metals. This results can be used to analysis of crashworthness.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.7-11
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• 2000

In this paper was studied on the mechanical characteristics of Glass Fiber Reinforced Plastics(GFRP) of the steel bar it is to replace. The advantage of FRP such as high strength, low weight and chemical inertness or noncorrosiveness can be fully exploited. GFRP bar were successfully fabricated at l0mm nominal diameters of solid and hollow types using a pultrusion method. Tensile and bending specimens from this bar were tested and compared with behavior of GFRP rebar and steel bar.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.419-425
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• 2001

The shear modulus of 3-bar lap rubber shear dynamic test specimen is investigated through incremented shear strain tests. The shear force-strain relation of rubber specimen is also calculated by ABAQUS using hyper-elastic material properties of high damping rubber. The analysis results are compatible with shear dynamic tests of 3-bar lap rubber specimen and 1/8 reduced-scale laminated rubber bearing

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.849-853
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• 2002

A specific experimental method, the split Hopkinson pressure bar (SHPB) technique has been widely used to determine the dynamic material properties under the impact compressive loading conditions with strain-rate of the order of 103/s~104/s. In this paper, dynamic deformation behaviors of rubber materials widely used for the isolation of vibration from varying structures under dynamic loading are determined using a Split Hopkinson Pressure Bar technique.

• 콘크리트학회지
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• 제10권6호
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• pp.169-178
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• 1998

고성능 belite 시멘트 콘크리트에 대한 부착특성에 대하여 코\ulcorner리트의 강도, 슬럼프, 배근위치, 피복두께 등의영향요인을 보단부시험체와 이음길이 보시험체를 통해 연구하였다. 동일한 압축강도의 1종 보통 포틀랜드 시멘트 콘크리트에 비해 부착강도는 약 10%증가하였고 압축강도 600kg/$\textrm{cm}^2$의고강도 belite 콘크리트에서 부착강도가 대체로 {{{{ SQRT { f'c} }} }}에 비례하였다. 유동성에 있어서 높은 슬럼프에 비해 ACI 318-95 규준에서 제시하는 상부근 계수 1.3이하의범위에 있었으며 이것은 고유동 belite 콘크리트가 블리이딩이나 골재분리가 적은 것으로 보여졌다. 또한 고강도 belite시멘트 콘크리트를 사용한 이음길이 보시험체에서 부착강도는 기존 예측식의 값보다다소 높게 나타났으며, 실리커흄, 플라이애쉬를 사용한 고강도 콘크리트 부착강도의 기존연구결과인 낮은 값과 차이를 보였다. 이상의 결과로 고유동, 고강도 belite 시멘트 콘크리트는 철근과의 부착성능이 다른 재료에 비해 양호한 것으로 나타났다.

• 한국구조물진단유지관리공학회 논문집
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• 제16권4호
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• pp.79-88
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• 2012

본 연구에서는 고강도 모르타르 충전식 기계적 슬리브 철근이음에 대한 단조가력 하에서의 강성을 보다 적절하게 평가하기 위하여, 슬리브 철근이음의 주요한 구조요소가 미치는 단조가력 하에서의 철근이음 강성에 대한 영향을 검토하였고 AIJ 규준에서 설정한 단조가력 하에서의 슬리브 철근이음에 대한 강성 기준과 비교평가하였다. 이것을 위하여 단조가력을 실시한 국내외 189여개 고강도 모르타르 충전식 기계적 슬리브 철근이음의 실험데이터를 조사하고 그 실험결과를 분석하였다. 그 결과, AIJ 규준에서 규정하는 목표 강성을 확보하는데 필요한 $f_g$(L/d)의 한계값을 철근의 종류와 슬리브의 종류에 따라서 각각 제시하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제11권6호
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• pp.169-180
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• 2007

본 연구에서는 SD500 고강도 철근에 적합한 강관 스플라이스 슬리브를 개발한 후에 실물크기의 20개 실험체를 제작하여 가력실험을 실시하였다. 그리고 강도를 비롯한 구조성능을 철근의 정착길이, 슬리브의 타입, 철근의 규격과 같은 실험변수에 따른 영향을 분석하고, 국내기준을 비롯한 주요기준에 따라서 비교, 평가하였다. 실험 결과는 SD500 고강도 철근용으로 개발된 강관 스플라이스 슬리브 철근이음은 주요기준에서 요구하는 구조성능을 가지고 있는 것으로 확인되었고 SD500 고강도 철근용 슬리브 철근이음에 대한 구조설계 기준 확립을 위한 기술적 자료를 제시하였다.

• 산업기술연구
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• 제25권B호
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• pp.171-174
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• 2005

In this paper, we propose a new data encoding algorithm for a two-dimensional bar code system. In general, the one-dimensional bar code is just a key which can access detailed information to the host computer database. But the two-dimensional bar code is a new technology which can obtain high density information without access to the host computer database. We implemented the encoding algorithm for Data Matrix bar code which is the most widely used among the many kinds of two-dimensional bar codes in the field of marking using Digital Signal Processor (TMS320C31). The performance of the proposed algorithm is verified by comparing the imprinted symbols on the steel surfaces with the codes which are decoded by a bar code reader.

• 한국지진공학회논문집
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• 제20권6호
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• pp.351-360
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• 2016

In regions of low-to-moderate seismicity, various types of lap splices are used for longitudinal reinforcement of columns at the plastic hinge zones. The seismic performance of such lap spliced columns, such as strength, deformation capacity, and energy dissipation, is affected by material strengths, longitudinal re-bar size, confinement of hoops, lap splice location, and lap splice length. In the present study, cyclic loading tests were performed for columns using three types of lap splices (bottom offset bar splice, top offset bar splice, and splice without offset bend). Lap splice length($40d_b$ and $50d_b$) was also considered as test parameters. Ties with 90-degree end hooks were provided in the lap splice length. The test results showed that strength, deformation capacity, and energy dissipation of columns significantly differed depending on the details and the length of lap splices. The bottom offset bar splice showed high ductility and energy dissipation but low strength; on the other hand, the top offset bar splice and the splice without offset bend showed high strength but moderate ductility and energy dissipation.

• Metals and materials international
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• 제24권6호
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• pp.1333-1345
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• 2018

The effect of manganese sulfide (MnS) inclusions on the machinability of free-cutting steel is based on their morphology, size and distribution. Furthermore, the plasticity of MnS is high during the hot working caused different characterization of MnS. In this study, the deformation behavior of MnS in 1215MS steel after a thermomechanical process was investigated at 1323 K. The microstructures of MnS inclusions were characterized by optical microscopy, scanning electron microscopy, energy-dispersive spectrometry, and electron backscattering diffraction (EBSD). As the thickness reduction of the inclusions increased from 10 to 70%, their average aspect ratio increased from 1.20 to 2.39. In addition, the deformability of MnS inclusions was lower than that of the matrix. The possible slip systems of A, B, C, and D plane traces were (${\bar{1}}0{\bar{1}}$)[${\bar{1}}01$], ($10{\bar{1}}$)[101], (011)[$01{\bar{1}}$], and (110)[$1{\bar{1}}0$]. Furthermore, the EBSD measurements suggested that slip planes in MnS inclusions occur on {110} planes.