• 대한조선학회논문집
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• 제33권3호
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• pp.48-55
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• 1996

본 연구의 목적은 좌초시 선저부의 찢김 응답에 대한 치수 및 동적 효과를 고찰하는 것이다. 이를 위해 판 및 종방향 보강재를 가진 보강판에 대해 판두께를 변화시킨 찢김 시리즈 실험을 수행하였으며, 본 실험 결과뿐 아니라 타연구자에 의해 수행된 기존의 찢김 실험 결과를 바탕으로 판의 찢김 응답에 대한 판두께의 치수 효과를 분석하였다. 또한, 기존의 이론적 및 실험적 연구 성과를 바탕으로 판의 찢김 응답에 대한 동적 효과를 고찰하였다. 특히, 연강재뿐 아니라 고장력강재의 항복강도에 대한 변형속도 효과를 정량적으로 규명하였다.

• Advances in materials Research
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• 제7권2호
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• pp.137-148
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• 2018

The present paper is a contribution in characterising end milling process of AISI 52100 ball bearing steel through statistical analyses of variance (ANOVA). The latter has been performed to identify the effect of the cutting parameters on the machined surface roughness and the cutting tool life. Wear measurements have been carried on multilayer coated carbide inserts and the respective surface roughness has been recorded. Taguchi's technique has been adapted to conduct the design experiments in terms of orthogonal arrays according to the cutting parameters (cutting speed, feed rate and depth of cut), the type of coating (TiN, TiCN, TiAlN) and lubricating condition. Regression analyses have conducted to the development of simplified empirical models that can be effectively used to predict surface roughness and tool wear in the present milling process.

• 한국물환경학회지
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• 제20권2호
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• pp.163-169
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• 2004

Feasibility of using PE sheet laminated CSP(Corrugated steel pipe) to sewers were tested via corrosion and abrasion tests for PE sheet laminated CSP; 1) corrosion test for PE film and PE coated plate, 2) corrosion test for joint of PE sheet laminated CSP, 3) corrosion test for outside of PE sheet laminated CSP, and 4) abrasion test for inside of PE sheet laminated CSP. The results for the corrosion and abrasion tests are as follows. 1. Results for corrosion tests on PE films and zinc coated steel plates that were coated with PE films show that the surfaces of both PE were not changed compared to those of original PE samples. Furthermore, PE films maintained strong adhesion on the steel plates even though they were exposed to sewage and seawater provided cutting planes of the steel plates were treated with molding. But, results for corrosion tests on the spots that were previously cut off by a knife and a cutting planes of the steel plates were treated without molding show that steel plates have been corroded if they were exposed to sewage and seawater. 2. Results for corrosion tests on joints of PE sheet laminated corrugated steel using sewage show that gathering rust was observed at cutting plane of PE sheet laminated corrugated steel after 180 days, but PE film was not flaked off. However, PE film at cutting plane was flaked off when PE sheet laminated corrugated steel was exposed to seawater. Furthermore, flaking process was severely progressed at lockseam points of which the surfaces were not smooth. 3. Results for laying PE sheet laminated corrugated steel under the ground show that the surface of untouched PE film was almost identical to that of original PE film. However, the spots that were previously cut off by a knife and a cutting plane of PE sheet laminated corrugated steel have flaked off. 4. As a result of abrasion tests conducted with PE sheet laminated corrugated steel and sand, brilliance and thickness of PE was not greatly changed under the severe abrasion conditions. Therefore, the durability of PE sheet laminated corrugated steel for abrasion was determined to be good.

• 터널과지하공간
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• 제10권4호
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• pp.516-525
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• 2000

최근, 도시 재개발과 산업설비 개·보수에 따른 노후화된 콘크리트 및 철근구조물에 대하여 환경 공해가 발생하지 않는 해체 기술 개발에 대한 요구가 급증하고 있다. 본 연구는 철근 구조물의 폭발절단 해체를 위한 성형폭약을 개발하기 위하여 폭발절단 효과에 영향을 주는 요소인 대상 구조물의 재질 및 형상, 두께와 강도 특성, 성형폭약의 형상, 폭약의 종류, 장약량, liner의 종류, stand-off distance, 성형폭약의 폭 및 너비, 기폭방법에 따른 영향과 폭발 절단시 발생되는 폭풍압에 의한 진동 및 소음의 영향 등을 검토함으로 폭발절단 최적조건을 선정하였다. 따라서, 본 연구를 통해 얻어진 폭발절단기술은 강교, 공장, 폐선박 등의 해체에도 적용될 것이다.

• 한국기계가공학회지
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• 제13권5호
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• pp.50-56
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• 2014

A technique based on the finite element method (FEM) is used in the simulation of metal cutting process. This offers the advantages of the prediction of the cutting force, the stresses, the temperature, the tool wear, and optimization of the cutting condition, the tool shape and the residual stress of the surface. However, the accuracy and reliability of prediction depend on the flow stress of the workpiece. There are various models which describe the relationship between the flow stress and the strain. The Johnson-Cook model is a well-known material model capable of doing this. Low-alloy steel is developed for a dry storage container for used nuclear fuel. Related to this, a process analysis of the plastic machining capability is necessary. For a plastic processing analysis of machining or forging, there are five parameters that must be input into the Johnson-Cook model in this paper. These are (1) the determination of the strain-hardening modulus and the strain hardening exponent through a room-temperature tensile test, (2) the determination of the thermal softening exponent through a high-temperature tensile test, (3) the determination of the cutting forces through an orthogonal cutting test at various cutting speeds, (4) the determination of the strain-rate hardening modulus comparing the orthogonal cutting test results with FEM results. (5) Finally, to validate the Johnson-Cook material parameters, a comparison of the room-temperature tensile test result with a quasi-static simulation using LS-Dyna is necessary.

• 대한기계학회논문집
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• 제16권4호
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• pp.707-722
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• 1992

본 연구에서는 공구의 큰 파손에서 부터 공구의 기하학적 형태가 크게 변하지 않는 작은 파손등 파손의 크기와 파손부위에 따른 신호의 형태를 조사하고자 한다. 그 방법으로서 가공재료로서는 SM45C강(steel)과 열처리한 SM45C강을 이용하였다. 공구파손에 따른 AE신호와 절삭력신호의 변화를 분석하기 위하여, AE신호의 경우는 RMS값을 택하고 그 진폭의 갑작스런 변화와 평균 레벨의 변화를 이용하여 파손의 순간 을 감지하였고, 절삭력의 경우에는 절삭력의 주분력, 이송분력 그리고 배분력의 변화 형태를 이용하여 공구의 이상상태를 알 수 있었으며, 이 두 신호의 변화를 동시에 관 찰함으로써 임의의 가공조건에서 공구의 파손을 감지할 수 있는 알고리즘 개발의 기준 을 마련할 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.878-881
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• 2000

Recently high speed machining is being studied actively to reduce machining time and to improve machining precision. To perform efficient high speed machining, evaluation of high speed machinability must be studied preferentially and it can be identified by investigation of cutting force, tool wear and surface roughness. In this study. the cutting force and tool wear and surface roughness are investigated in case of various cutting conditions for hardened die steel.

• Steel and Composite Structures
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• 제19권6호
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• pp.1467-1481
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• 2015

This paper presents a contribution to improving an analytical thermo-mechanical modeling of Oxley's machining theory of orthogonal metals cutting, which objective is the prediction of the cutting forces, the average stresses, temperatures and the geometric quantities in primary and secondary shear zones. These parameters will then be injected into the developed model of Karas et al. (2013) to predict temperature distributions at the tool-chip-workpiece interface. The amendment to Oxley's modified model is the reduction of the estimation of time-related variables cutting process such as cutting forces, temperatures in primary and secondary shear zones and geometric variables by the introduction the constitutive equation of Johnson-Cook model. The model-modified validation is performed by comparing some experimental results with the predictions for machining of 0.38% carbon steel.

• Structural Engineering and Mechanics
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• 제61권4호
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• pp.519-526
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• 2017

In the present paper, the effects of cutting parameters and coating material on the performances of cutting tools in turning of AISI 52100 steel are discussed experimentally. A comparative study was carried out between uncoated and coated (with TiCN-TiN coating layer) cermet tools. The substrate composition and the geometry of the inserts compared were the same. A mathematical model was developed based on the Response Surface Methodology (RSM). ANOVA method was used to quantify the effect of cutting parameters on the machining surface quality and the cutting forces. The results show that feed rate has the most effect on surface quality. However, cutting depth has the significant effect on the cutting force components. The effect of coating layers on the surface quality was also studied. A lower surface roughness was observed when using PVD (TiCN-TiN) coated insert. A second order regression model was developed and a good accuracy was obtained with correlation coefficients in the range of 95% to 97%.

• Journal of Ship and Ocean Technology
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• 제1권1호
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• pp.48-56
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• 1997

This paper deals with the energy dissipation of ductile metal plate due to cutting. By using nondimensional analysis, we present that the dissipation energy of tearing behaviour can be formulated as a function of slenderness ratio expressed by cutting length, yield stress, plate thickness and elastic modulus. The validity of the proposed formula for Al-alloy, copper and mild steel is demonstrated by comparing the proposed formula with experimental results, which are shown in good agreements except for thick mild steel plate.