• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.3
• /
• pp.9-14
• /
• 2015

The Direct Metal Tooling (DMT) process is a kind of additive manufacturing processes, which is developed using various commercial steel powders, such as P20, P21, SUS420, and other non-ferrous metal powders. The DMT process is a versatile process that can be applied to various fields, such as the molding industry, the medical industry, and the defense industry. Among them, the application of the DMT process to the molding industry is one of its most attractive and practical applications, since the conformal cooling channel cores of injection molds can be fabricated at a slightly expensive cost by using the hybrid fabrication method of DMT technology compared with parts fabricated with machining technology. The main objectives of this study are to provide various characteristics of the parts made using the DMT process compared with the same parts machined from bulk materials and evaluate the performance of the injection mold equipped with a conformal cooling channel core fabricated using the hybrid method of the DMT process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.10a
• /
• pp.17-18
• /
• 2006

• Journal of Welding and Joining
• /
• v.32 no.4
• /
• pp.10-14
• /
• 2014

Laser aided Direct Metal Tooling(DMT) process is a kind of Additive Manufacturing processes (or 3D-Printing processes), which is developed for using various commercial steel powders such as P20, P21, SUS420, H13, D2 and other non-ferrous metal powders, aluminum alloys, titanium alloys, copper alloys and so on. The DMT process is a versatile process which can be applied to various fields like the mold industry, the medical industry, and the defense industry. Among of them, the application of DMT process to the mold industry is one of the most attractive and practical applications since the conformal cooling channel core of injection molds can be fabricated at the slightly expensive cost by using the hybrid fabrication method of DMT technology compared to the part fabricated with the machining technology. The main objectives of this study are to provide various characteristics of the parts made by DMT process compared to the same parts machined from bulk materials and prove the performance of the injection mold equipped with the conformal cooling channel core which is fabricated by the hybrid method of DMT process.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.4B
• /
• pp.257-269
• /
• 2003

S(Synchrous)-DMT(Discrete Multi Tone) is an emerging cable modem technology applicable to the upstream channel for high speed multimedia communication. In this paper we analyze the transmitting and receiving process of S-DMT scheme and derive bit error probability of S-DMT scheme in the $\varepsilon$-mixture impulse noise model which appropriately reflects impulse noise model which approproately reflects impulse noise characteristics of upstream channel. The analysis results show a good match with the simulation results. We also compare Eb/No gain performance of S-DMT with TDMA in 16-, 32-, 64-QAM.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.8
• /
• pp.56-63
• /
• 2020

The heat transfer phenomenon in the vicinity of the irradiated region of a focused laser beam of a DMT process greatly affects both the deposition characteristics of powders on a substrate and the properties of the deposited region. The goal of this paper is to investigate the heat transfer characteristics of a single bead deposition of Inconel 718 powders on S45C structural steel using a laser-aided direct metal tooling (DMT) process. The finite element analysis (FEA) model with a Gaussian volumetric heat flux is developed to simulate a three-dimensional transient heat transfer phenomenon. The cross-section of the bead for the FEA is estimated with an equivalent area method using experimental results. Through the comparison of the results of the experiments and those of the analysis, the effective beam radius of the bottom region of the volumetric heat flux and the efficiency of the heat flux model for different powers and travel speeds of the laser are predicted. From the results of the FEA, the influence of the power and the travel speed of the laser on the creation of a steady-state heat transfer region and the formation of the heat-affected zone (HAZ) in the substrate are investigated.

• Applied Chemistry for Engineering
• /
• v.26 no.5
• /
• pp.621-623
• /
• 2015

This article describes a purification method yielding high purity of MFB produced from DMT production process. Aldehyde functional group of MFB included in side-products were converted to acetal compound via reacting with methanol and further separated. Hydrolysis process of the acetal product was continued under acidic condition and highly pure MFB were obtained with 90% yield. The structure of MFB was analyzed by $^1H$ NMR and $^{13}C$ NMR spectroscopy. Also, the purity of MFB was estimated to be over 99% by GC analysis.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 2001.11a
• /
• pp.91-91
• /
• 2001

Nramp2, also known as DMT1 and DCT1, is a 12-transmembrane domain protein responsible for dietary iron uptake as well as metal ions such as lead, manganese, zinc, copper, nickel, cadmium, and cobalt. High expression of DMT1 increase lead uptake, and DMT1-dependent lead transport was H -dependent and inhibited by iron ions. The molecular mechanism of lead transport in CNS is as yet unknown. although interactions between iron and lead at the level of absorption have been known for some time. The process of lead uptake into astrocytes was not known yet. Nramp2 may mediate transport of heavy metal into astrocytes. We investigated whether Nramp2 mediate transport of lead into astrocytes. And we do whether Nramp2 was expressed highly by deprivation of iron in Astrocytes, and lead uptake into astrocytes was influenced by expression of Nramp2. Immortalized human fetal astrocyte(SV-FHA) cells were cultured in medium containing Dulbecco's modified Eagle's medium and treated with Deferoxamine. Northern blot analysis was done for determining mRNA level of DMT1 and lead uptake assay was done in incubation condition of pH 5.5 and 7.4.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.12
• /
• pp.1093-1100
• /
• 2014

The goal of this paper is to investigate preliminary the applicability of 3D printing technologies for the development of the hot bulk forming process and die. 3D printing technology based on the plastic material was applied to the preform design of the hot forging process. Plastic hot forging dies were fabricated by Polyjet process for the physical simulation of the workpiece deformation. The feasibility of application of Laser-aided Direct Metal Rapid Tooling (DMT) process to the fabrication of the hot bulk metal forming die was investigated. The SKD61 hot-working tool steel was deposited on the heat treated SKD61 using the DMT process. Fundamental characteristics of SKD 61 hot-working tool steel deposited specimen were examined via hardness and wear experiments as well as the observation of the morphology. Using the results of the examination of fundamental characteristics, the applicability of the DMT process to manufacture hot bulk forming die was discussed.

• Journal of Navigation and Port Research
• /
• v.32 no.8
• /
• pp.629-636
• /
• 2008

Dual Mode Trailer(DMT) systems are significantly considered as future transportation technique particularly to eliminate complicated job process in the railroad based transportation and reduce relevant logistic cost in economic viewpoint. This paper presents survey of Dual Mode Trailer(DMT) systems in terms of technical applicability in domestic industry, technical trends, etc. We provide several DMT systems addressed until now and propose suitable framework of them to our nation.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.18 no.11
• /
• pp.103-108
• /
• 2019

The cooling rate and the uniformity of mold temperature, in the injection molding process, possess great influences on the productivity and quality of replications. The conformal cooling channel, which is of a uniform spacing from the mold cavity by the metal additive manufacturing process, receives much attention recently. The purpose of this study is to develop a mold core with a curved conformal cooling channel for a pottery-shaped thick-wall cosmetic container through the hybrid method of direct metal tooling (DMT) process. In this study, we design a mold core that contains the curved cooling channel for the container. A method that divides the cavity is proposed and the DMT process is carried out to form the curved cooling channel. The test mold core, with the curved conformal cooling channel, has been fabricated by the proposed method to confirm the feasibility of the design concept. We show that no leakage is observed for the additive manufactured test mold core, and its physical properties demonstrate that it can be sufficiently used as the injection mold core.