• Journal of Korea Foundry Society
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• v.44 no.2
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• pp.49-55
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• 2024

• Journal of Korea Foundry Society
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• v.44 no.2
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• pp.43-48
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• 2024

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.103-109
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• 2017

Metal 3D printing, which is an additive metal manufacturing (AMM) process, enables the development of full-density metallic tools and parts using metal powders that are precisely delivered and controlled for deposition with no powder bed. However, some unknown geometric defects and irregular geometric features on an STL model can possibly result in incorrect metal part fabrication after the build. This study first proposes a methodical approach for verifying the build part, including the missing facet problems in an STL model, by defining some irregular features that possibly exist on the part. Second, 2D tool paths on each build layer were investigated for detecting any singular region inside the layer. The method was implemented for building two sample STL models using a direct energy deposition process, and finally, it was visually simulated for diagnosis.

• Journal of Digital Convergence
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• v.10 no.10
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• pp.431-437
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• 2012

In today's modern society, since the Industrial Revolution took place, still lots of goods have been produced in quantity. However, human's instinct has been growing bigger and bigger that he or she wants to possess the works or products of scarcity and aesthetic value of a sculpture handmade by craftsmen, not mass-produced with the same design patterns. Accordingly, it is required that an artist be concerned about the value of figuring out and pursuing an individual's lifestyle, his/her needs and inherent desires. Moreover, by means of visualization technique, an artist should provide the public with several scenarios about the future, letting them choose the one they want democratically. Therefore, with the help of Mokumegane technique, one of the traditional metal crafts techniques, which shows certain organic patterns joining different metals, this research aims for the inheritance of traditional techniques and the objective preparation for high-quality crafts market, studying the patterns expressed on the surface of metals, which are hard to find through machines.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.8
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• pp.773-780
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• 2015

Traditionally, additive manufacturing (AM) technology has been used to fabricate prototypes in the early development phase of a product. This technology is being applied to release manufacturing of a product because of its low cost and fast fabrication. AM technology is a process of joining materials to fabricate a product from the 3D CAD data in a layer-by-layer manner. The orientation of a layer during manufacturing can affect the mechanical properties of the product because of its anisotropy. In this paper, tensile testing of polymer-based specimens were built with a typical AM process (FDM, PolyJet and SLA) to study the mechanical properties of the AM materials. The ASTM D 638 tensile testing standard was followed for building the specimens. The mechanical properties of the specimens were determined on the basis of stress-strain curves formed by tensile tests. In addition, the fracture surfaces of the specimens were observed by SEM to analyze the results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.881-886
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• 2014

The purpose of three-dimensional (3-D) metal printing using 5-axis is to deposit metal powder by changing the orientation of the deposited structure to be built for the overhang or undercut feature on part geometry. This requires a complicated preprocess functionality of providing three dimensionally sliced layers to cover the required part geometry. This study addresses the overhang/undercut problem in 3-D metal printing and discusses a possible solution of providing 3-D layers to be built using the DMT(R) machine.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.327-330
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• 2004

Laser aided direct metal deposition (LADMD) process offers the ability to make a metal component directly from 3-D CAD dimensions. A 3-D object can be formed by repeating laser cladding layer by layer. The key of the build-up mechanism is the effective control of powder delivery and laser power to be irradiated into the melt-pool. A feedback control system using optical sensors is introduced to control laser power and powder mass flow rate. Using H13 tool steel and $CO_2$ laser system, comprehensive analysis are executed to test the efficiency of the system. In addition, the dimensional characteristics of directed deposited material are investigated with the parameters of deposition thickness, laser power, traverse speed and powder mass flow rate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.552-556
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• 1997

The Direct Metal Prototyping(DMP), one of the rapid prototyping technologies, allows the manufacturing of three-dimensional metallic parts using metal powders directly from the CAD data. Laser power and scanning speed are the most important variables of the process. The objective of this study is to obtain the design data for laser power and scanning speed to bond metal powders effectively using the finite element method. To obtain the design values, a numerical analysis considering two-dimensional heat transfer during the sintering of metal powder layers of the process was performed. The laser beam has been modeled to have directionality in its heat flux distribution, i. e., in the scanning direction a Gaussian beam mode distribution has been assumed and in the thickness direction a square beam mode distribution. The three-dimensional irregular distribution of metal powders of the powder layer is idealized as two-dimensional distribution in which metal powders are located regularly and periodically on the plate. In this study the design values of laser power vs scanning speed have been obtained. Temperature distribution and temperature variation of the powder layers with respect to time have been predicted. The commputed dsign data will be useful in determining the initial conditions of the process.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.56-62
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• 2000

A fast and precise technique to make 3-dimensional object which is called direct metal shaping process is processed. It is very useful technique in design and inspection. Using this developed system, a solid object is made. In experiment, test parts are built by varying three factors, laser power, scan path, scan speed. This process used device, which is different from the widely used in rapid prototyping in that powder feeding device is used. Spraying powder directly at the focused laser beam and then three dimensional object is made by the deposit of melted metal powder. The optimum scanning path is found to be zigzag path, which had little thermal affection on base metal. As a result of these experiments, it was found that optimum scanning speed is 15mm/sec laser power is 50W. This constructed 3-dimensional object could be used in mold manufacturing directly.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.308-308
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• 2004

쾌속조형기술은 설계형상의 확인, 시작품의 제작, 금속 및 세라믹 부품에의 응용, 동시공학, 의료, 마이크로 머신 둥 제조업 전반에 걸쳐서 많은 응용이 이루어지고 있다 여러 가지의 기술들이 개발되고 이를 응용한 장비들이 생산되어 보급됨으로써 이러한 적용분야들은 점차 확대되고 있다. 본 연구에서는 분말을 소결, 적층하여 원하는 형상을 만들어내는 SLS(Selective Laser Sintering) 장비를 개발하는데 있어서 레이저 경로의 제어를 통한 분말을 소결시키는 부분인 레이저 주사 시스템(laser scanning system)을 개발하고자 한다.(중략)