• Korean Journal of Materials Research
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• v.8 no.7
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• pp.628-633
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• 1998

단사정 HBO2 분막을 무기접착제로 이용하여 선택적 레이저 소결 기술을 적용시켜 알루미나-글래스 복합재료를 제조하였다. 만들어진 green SLS 시험편을 여러 온도에서 열처리하여 글래스-세라믹 복합재료를 얻었다. 글래스의 양이 많을수록 복합재료는 높은 밀도와 높은 굽힘강도를 보여주었다. 열처리 온도 $900^{\circ}C$에서 복합재료는 최대 밀도와 최대 강도를 나타낸다. 이것은 글래스의 낮은 점도로 인한 좋은 유동성 때문에 글래스의 재분배가 이루어졌기에 가능하다고 생각되어진다. 그리고 기공이 많은 열처리한 SLS 시험편에 콜로이드 실리카를 주입시켜 치밀화시켰다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.423-424
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.225-226
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• 2007

• Journal of the Korean Society for Precision Engineering
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• v.25 no.7
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• pp.7-12
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• 2008

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.2054-2063
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• 2020

The high-temperature oxidation behavior of ZrSi₂ used as a coating material for nuclear fuel cladding was investigated for developing accident-tolerant fuel cladding of light water reactors. Bulk ZrSi₂ samples were prepared by spark plasma sintering. In situ X-ray diffraction was conducted in air at 900, 1000, and 1100 ℃ for 20 h. The microstructures of the samples before and after oxidation were examined by scanning electron microscopy and transmission electron microscopy. The results showed that the oxide layer of zirconium silicide exhibited a layer-by-layer structure of crystalline ZrO₂ and amorphous SiO₂, and the high-temperature oxidation resistance was superior to that of Zircaloy-4 owing to the SiO₂ layer formed. ZrSi₂ was coated on the Zircaloy-4 tube surface using laser 3D printing, and the coated tube was oxidized for 2000 s at 1200 ℃ under a vapor/argon mixture atmosphere. The outer surface of the coated tube was hardly oxidized (10-30 ㎛), while the inner surface of the uncoated tube was significantly oxidized to approximately 300 ㎛.

• Transactions of Materials Processing
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• v.29 no.1
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• pp.44-48
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• 2020

Aluminum nitride (AlN), as a substrate material in electronic packaging, has attracted considerable attention over the last few decades because of its excellent properties, which include high thermal conductivity, a coefficient of thermal expansion that matches well with that of silicon, and a moderately low dielectric constant. AlN films with c-axis orientation and thermal conductivity characteristics were deposited by using Pulsed Laser Deposition (PLD). The epitaxial AlN films were grown on sapphire (c-Al₂O₃) single crystals by PLD with AlN target and Y₂O₃ doped AlN target. A comparison of different targets associated with AlN films deposited by PLD was presented with particular emphasis on thermal conductivity properties. The quality of AlN films was found to strongly depend on the growth temperature that was exerted during deposition. AlN thin films deposited using Y₂O₃-AlN targets doped with sintering additives showed relatively higher thermal conductivity than while using pure AlN targets. AlN thin films deposited at 600℃ were confirmed to have highly c-axis orientation and thermal conductivity of 39.413 W/mK.

• Journal of Powder Materials
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• v.18 no.5
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• pp.406-410
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• 2011

Green strength is an important property of powders since high green strength guarantees easy and safe handling before sintering. The green strength of a powder compact is related to mainly mechanical and surface characters, governed by interlocking of the particles. In this study, the effect of powder surface roughness on the green strength of iron powders was investigated using a transverse rupture test. Three-dimensional laser profiler was employed for quantitative analyses of the surface roughness. Two different surface conditions, i.e. surface roughness, of powders were compared. The powders having rough surfaces show higher green strength than the round surface powders since higher roughness leads increasing interlocked area between the contacting powders.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.2
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• pp.126-130
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• 2002

This paper presents the basic concept of new solid freeform fabrication system using rapid prototyping method. The system could fabricate an arbitrary ceramic form by laser cutting, transferring, stacking, and sintering of each slide. The system consists mainly of laser apparatus. X-Y table, a slide transferring system, and electric oven. The system could fabricate an object that has smooth surface with comparatively short period of time. The system is effective in terms of its direct fabrication capability without second mechanical process. The fabricated shape could directly be used as part of a whole assembly and therefore its method could be applied to various application areas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.261-268
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• 2017

In this paper, we propose an FSSH(Folded Slot Spherical Helix) magnetic dipole antenna with a form factor easy to build and study its radiation properties. The number of folded arms, the gap between them and the metal thickness are tuned to achieve relatively simple structure to realize whereas maintaining high radiation efficiency at an electrically small size. The proposed design shows wide radiation efficiency bandwidth and it is confirmed by circuit simulation that the non-Foster impedance matching techniques could be utilized for its practical use. The prototype of the proposed antenna is built with the aid of an SLS(Selective Laser Sintering) 3D printing technology. The measured result shows lower Q impedance characteristic due to high resistive loss of the copper tape joints.

• Elastomers and Composites
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• v.44 no.2
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• pp.106-111
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• 2009

Tissue engineering is a research field for artificial substitutes to improve or replace biological functions. Scaffolds play a important role in tissue engineering. Scaffold porosity and pore size provide adequate space, nutrient transportation and cell penetration throughout the scaffold structure. Scaffold structure is directly related to fabrication methods. This review will introduce the current technique of 3D scaffold fabrication for tissue engineering. The conventional technique for scaffold fabrication includes salt leaching, gas foaming, fiber bonding, phase seperation, melt moulding, and freeze drying. These conventional scaffold fabrication has the limitations of cell penetration and interconnectivity. In this paper, we will present the solid freeform fabrication (SFF) such as stereolithography (SLA), selective laser sintering (SLS), and fused deposition modeling (FDM), and 3D printing (3DP).