• 한국생산제조학회지
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• 제23권4호
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• pp.330-336
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• 2014

The continuous chip generated in cutting process deteriorates workpiece, tool, and machine tool system. It is necessary to treat this continuous chip in ductile material machining condition for stable cutting. This paper deals with the chip control method using acoustic emission(AE) signal in pure copper turning operation. AE raw signals, root mean square(RMS) signals and wavelet transformed signals measured in turning process are introduced to analysis for chip patterns. With analysis of AE signals, it is obtained that the produced chip patterns are correlated with the specified AE signals which are transformed by fuzzy pattern algorithm. By this experimental investigation, the chip patterns can be classified at significant level in pure copper machining process and controlled from continuous chips to reduced-length stable chips.

• 한국기계가공학회지
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• 제17권1호
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• pp.63-68
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• 2018

At present, ultra-precision cutting technology has been studied in Korean research institutes, focusing on development of ultra-precision cutting tool technology and ultra-precision control engineering. However, the developed technologies are still far behind advanced countries. It focuses on metals including aluminum, copper and nickel, and nonmetals including plastics, silicone and germanium which require high precision while using a lathe. It is hard to implement high precision by grinding the aforementioned materials. To address the issue, the ultra-precision cutting technology has been developing by using ultra-precision machine tools very accurate and strong, and diamond tools highly abrasion-resistant. To address this issue, this study aims to conduct ultra-precision cutting by using ECTS (Error Compensation Tool Servo) to improve motion precision of elements and components, and compensate for motion errors in real time. An IR camera is used for analyzing cutting accuracy differences depending on the heat generated in diamond tools in cutting to examine the heat generated in cutting to study cutting accuracy depending on generated heat.

• 한국기계가공학회지
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• 제12권6호
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• pp.37-44
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• 2013

Friction stir welding (FSW) is a solid state joining technique that has expanded rapidly since its development in 1991 and has numerous applications in a wide variety of industries. This paper introduces the basic principles of friction stir welding (FSW) and presents a survey of the latest technologies and applications in the field. The basic principles that are discussed include the terminology, tool/workpiece processes, FSW merits and process variants. In particular, the process variants including the rotation speed and traveling speed are discussed, which include the defect-free zone in an oxygen free copper and Al alloy, respectively. Multiple aspects of the FSW machine are developed, including a horizontal 2D FSW machine and a hybrid complex FSW machine. The latest applications are introduced, with an emphasis on the recent advances in the aerospace, automotive, and IT display industries. Finally, the direction for future research and potential applications are examined.

• 한국산학기술학회논문지
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• 제20권8호
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• pp.657-661
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• 2019

자동차 산업은 전 세계적으로 매출액이 1조 달러가 넘고 1천만 명 이상을 고용하고 있는 세계최대 제조업으로서, 약 2만 여개의 부품으로 완성되는 복합적 성격의 대표적인 산업이며 자동차 조립공정은 도장된 차체에 약 3천여 종의 내장, 계기판, 시트, 유리, 엔진, 트랜스미션, 차축 등의 유닛(Unit)을 조립하는 노동집약적 공정으로, 타 공정에 비해 자동화 비율이 가장 낮은 특징을 가지고 있다. 또한, 현재의 자동차 조립공정은 작업자의 조립작업에 대한 실시간 모니터링이 이루어지고 있지 못한 실정으로, 작업자의 작업 공구위치 측정시스템의 도입을 통해 공구의 위치를 실시간으로 파악하고 분석하여 일관된 작업 순서를 지시하면서 작업의 누락 및 가감을 체크한다면, 자동차 제조공정에서 발생할 수 있는 불량을 사전에 차단하여 조립공정의 생산성 및 품질향상을 이룰 수 있다. 따라서 본 논문에서는 작업자의 작업공구 위치 측정 시스템의 도입을 통해 일관된 작업 순서를 지시하면서 작업의 누락 및 가감을 체크하고, 제조공정에서 발생할 수 있는 조립불량을 사전에 차단하여 조립공정의 생산성 및 품질향상을 이룰 수 있는 실시간 공구 위치추적 시스템의 구성을 위하여 UWB(Ultra Wide Band) 무선측위를 활용한 공구의 실시간 위치추적시스템을 개발하고 그 효용성을 증명하고자 한다.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.45-49
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• 2010

The automotive industry has shown a growing interest in tube hydroforming during the past years. The advantages of hydroforming (less thinning, a more efficient manufacturing process, etc.) can, for instance, be combined with the high strength of extra high strength steels, which are usually less formable, to produce structural automotive components which exhibit lower weight and improved service performance. Design and production of tubular components require knowledge about tube material and forming behavior during hydroforming and how the hydroforming operation itself should be controlled. These issues are studied analytically in the present paper. In this study, the whole process of rear sub-frame parts development by tube hydroforming using AA6061 material is presented. At the part design stage, it requires feasibility study and process design aided by CAE (Computer Aided Engineering) to confirm hydroformability in details. Effects of parameters such as internal pressure, axial feeding and geometry shape in automotive rear sub-frame by hydroforming process were carefully investigated. Overall possibility of hydroformable rear sub-frame parts could be examined by cross sectional analyses. Moreover, it is essential to ensure the formability of tube material on every forming step such as pre-bending and hydroforming. In addition, all the components of prototyping tool are designed and interference with press is examined from the point of geometry and thinning.

• 한국기계가공학회지
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• 제15권3호
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• pp.86-92
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• 2016

Mechanical milling, in association with electrical discharge machining (EDM) for hybrid machining, is presented in this paper. An end mill cutting tool, an electrode of the EDM, was used for the system. That means that some parts were cut by the mechanical cutting process and others by the EDM. The possibility of combining both processes was simulated with the cutting simulation software. In addition, the machining reality was verified by measuring the electrical signal from the EDM power supply, which was measured in time and frequency domains. From this initial research, the hybrid machining system proposed in this paper appears to be well suited for difficult to cut material processing.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.310-315
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• 1997

An extensive corrosion study was initiated by galvalume steel sheet manufacturing company to clarify the corrosion behavior of zinc and zinc and zinc-alloy coated automotive sheet steel in out panel and electrical application. Since the early 1980's the use of zinc and aluminum alloy coated steel for vehicular corrosion protection has increased drastically. This paper describes the evaluation of formability, weldability and painted corrosion performance of galvalume steel sheet. This paper presents an overview of the program and some initial test results on the weldability, lifetime of the electrode tip shape of the spot welding and corrosion protection. Galvalume steel sheet improved corrosion performance and spot weldability of galvalume steel has no problem for the variation of welding current. And tip lifetime was changed according to the influence of shape.

• 한국기계가공학회지
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• 제9권6호
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• pp.43-50
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• 2010

This study aims to analyze the structural safety by comparing deformation and equivalent stress of door with a stiffener or no stiffener when the door crashes against something in case of overturn. Three types are classified on the basis of the no stiffener model in the vehicle door. One is the type which has a stiffener. Another is the type which has no stiffener and the other is the type which has a hole in the stiffener. These three types are compared with each other by analyzing. This side door of vehicle is the automotive part about the kind of vehicle as Mercedes Benz E-Klasse scaled down as 1/18 times as the real size. The study model of vehicle door is modelled by CATIA program and it is analyzed by ANSYS.

• 한국기계가공학회지
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• 제12권4호
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• pp.81-86
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• 2013

For a 2-dimensional(2D) vibration milling, an excitation work-table was developed using two piezoelectric materials orthogonally arranged, where the trochoidal trajectory of a milling tool is combined with 2 dimensional elliptical vibration of a work-table. Applying 3kHz excitation frequency and 7~8mm amplitude of vibration to micro milling process with brass and nickel materials, the roughness in both bottom and side surface is much more improved compared to the surface by conventional milling process, which is attributed to decreased frictional force, increased cutting speed, and rubbing effect of a 2 dimensional vibration.

• 한국생산제조학회지
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• 제18권4호
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• pp.417-422
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• 2009

The injection mold cooling circuit optimization was studied with a response surface method in the previous research. It took so much time to find an optimum solution for a large product due to an extensive amount of calculation time for the CAE analysis. In order to use the optimization technique in the actual design process, the calculation time should be much reduced. In this study, we tried to reduce the number of design variables with the concept of the close relationship between the depth and the distance of cooling channel. The optimum ratio of the distance to the depth of cooling channels for a 2-dimensional problem was 2.0 so that the optimum ratio was again sought out for 4 large automotive parts. Therefore, the number of design variables for the cooling circuit optimization can be reduced in half, resulting in much faster running time for the optimization as a design tool.