• Journal of Powder Materials
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• v.29 no.1
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• pp.34-40
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• 2022

Recently, high-entropy carbides have attracted considerable attention owing to their excellent physical and chemical properties such as high hardness, fracture toughness, and conductivity. However, as an emerging class of novel materials, the synthesis methods, performance, and applications of high-entropy carbides have ample scope for further development. In this study, equiatomic (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide powders have been prepared by an ultrahigh-energy ball-milling (UHEBM) process with different milling times (1, 5, 15, 30, and 60 min). Further, their refinement behavior and high-entropy synthesis potential have been investigated. With an increase in the milling time, the particle size rapidly reduces (under sub-micrometer size) and homogeneous mixing of the prepared powder is observed. The distortions in the crystal lattice, which occur as a result of the refinement process and the multicomponent effect, are found to improve the sintering, thereby notably enhancing the formation of a single-phase solid solution (high-entropy). Herein, we present a procedure for the bulk synthesis of highly pure, dense, and uniform FCC single-phase (Fm3m crystal structure) (Hf-Ti-Ta-Zr-Nb)C high-entropy carbide using a milling time of 60 min and a sintering temperature of 1,600℃.

• Journal of Powder Materials
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• v.29 no.5
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• pp.363-369
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• 2022

AlSi10Mg alloys are being actively studied through additive manufacturing for application in the automobile and aerospace industries because of their excellent mechanical properties. To obtain a consistently high quality product through additive manufacturing, studying the flowability and spreadability of the metal powder is necessary. AlSi10Mg powder easily forms an oxide film on the powder surface and has hydrophilic properties, making it vulnerable to moisture. Therefore, in this study, AlSi10Mg powder was hydrophobically modified through silane surface treatment to improve the flowability and spreadability by reducing the effects of moisture. The improved flowability according to the number of silane surface treatments was confirmed using a Carney flowmeter. In addition, to confirm the effects of improved spreadability, the powder prior to surface treatment and that subjected to surface treatment four times were measured and compared using s self-designed recoating tester. The results of this study confirmed the improved flowability and spreadability based on the modified metal powder from hydrophilic to hydrophobic for obtaining a high-quality additive manufacturing product.

• Design & Manufacturing
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• v.17 no.4
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• pp.42-51
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• 2023

In this study, we investigated the injection molding technology of thick-walled light guides, which are parts that control the light source of automotive lamps. Through injection molding analysis, the gate position that can minimize product shrinkage and deformation was selected, and a mold reflecting the analysis results was manufactured to evaluate the effect of injection speed and holding pressure on transferability during micro-pattern molding through experiments. When designing an injection mold for products with varying thicknesses, it was found that installing the gate on the side of the thicker part was advantageous for reducing volume shrinkage and deformation. It was found that the effect of shrinkage due to thickness may be greater than the position of the gate on pattern transferability. The pattern transfer error decreased as the injection speed and holding pressure increased, and it was found that increasing the injection speed was relatively effective.

• Bulletin of Food Technology
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• v.25 no.1
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• pp.108-114
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• 2012

본 내용은 일본의 소금 생산시설 및 운영기술 현지조사를 위하여 2012. 1. 8 ~ 1. 11, 3박 4일 간 일본의 대표적인 소금생산지역인 오키나와 지역을 방문하여 소금 생산공정 및 운영기술, 관련 제품 생산현황, 소비현황 등을 조사하였다.

• Journal of the Korean institute of surface engineering
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• v.57 no.2
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• pp.105-114
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• 2024

Tempering behavior and mechanical properties in AISI H13 steel, quenched and tempered from 300 ℃ to 700 ℃ for different tempering time (1, 2, 5, 10, 20 hr) were quantitatively investigated by scanning electron microscopy (SEM), x-ray diffractometer (XRD), impact test machine, rockwell apparatus, ball-on-disk tester. Under the condition that the tempering time is 2 hours, the hardness increases slightly as the tempering temperature increases, but decreases rapidly when the tempering temperature exceeds 500 ℃, while the impact energy increases in proportion to the tempering temperature. Friction tests were conducted in dry condition with a load of 30 N, and the friction coefficient and wear rate according to tempering conditions were measured to prove the correlation with hardness and microstructure. In addition, primary tempering from 300 ℃ to 700 ℃ was performed at various times to establish a kinetic model to predict hardness under specific tempering conditions.

• Corrugated packaging logistics
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• s.110
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• pp.46-55
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• 2013

국내 패키징 산업의 규모와 현황을 분석, 추정하기 위하여 산업통상자원부와 생산기술연구원(패키징기술센터)이 '2012년 패키징 산업 통계조사'를 실시하였으며, 조사 결과 국내 패키징 산업 시장 규모는 지속적인 성장세를 보이고 있는 것으로 나타났다. 2011년도 패키징 산업 매출액 규모는 총33조 4,227억원으로 추정되었고 2010년(31조 2,932억원) 대비 68% 증가하였으며, 이는 세계 패키징 시장(약 6,700억 달라 2016년까지 8,200억 달러 3% 성장률) 성장률의 2배로 빠르게 증가하는 것으로 조사되었다. 이와 관련하여 '2012년도 패키징산업 통계조사 결과'를 요약한 내용 전문을 한국생산기술연구원 패키징기술센터로부터 입수 받아 본 잡지에 게재하오니 독자 여러분의 많은 활용 바랍니다.

• The Science & Technology
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• v.28 no.9 s.316
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• pp.31-34
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• 1995

• Tunnel and Underground Space
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• v.32 no.6
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• pp.345-352
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• 2022

The existing NATM (New Austrian Tunneling Method) has induced civil compliants due to blasting vibration and noise. Machanized excavation methods such as TBM (Tunnel Boring Machine) are being adopted in the planning and construction of tunneling projects. Shield TBM method is composed of repetition processes of TBM excavation and segment installation, the machine has to be stopped during the later process. Consecutive excavation technology using helical segment is under developing to minimize the stoppage time. The modification of thrust jacks and module are planned to ensure the advance force acting on the inclined surface of helical segment. Also, the integrated system design of hydraulic circuit will be remodeled. This means that the system deactivate the jacks on the installing segment while the others automatically act the thrusting forces on the existing segments. This report briefly introduces the mechanical research part of the current consecutive excavation technological development project of TBM.

• Electrical & Electronic Materials
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• v.34 no.6
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• pp.32-41
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• 2021

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.5
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• pp.499-506
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• 2022

This study proposes kinetic parameters of Ru catalyst for steam methane reforming (SMR). First, extensive experiments are performed under different SMR conditions to evaluate performance of the catalyst in SMR. Second, a kinetic model is designed and developed for parameter estimation and validation using gPROMS. Finally, estimated parameters are fitted to the kinetic model and then, the model results are compared with the experimental data. The model results are in a good agreement with the experimental data.