• 한국세라믹학회지
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• 제51권6호
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• pp.539-543
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• 2014

Foam type porous silicon carbide ceramics were fabricated by a polymer replica method using polyurethane foam, carbon black, phenol resin, and silicon powder as raw materials. The influence of the C/Si mole ratio of the ceramic slurry and heat treatment temperature on the porous silicon carbide microstructure was investigated. To characterize the microstructure of porous silicon carbide ceramics, BET, bulk density, X-ray Powder Diffraction (XRD), and Scanning Electron Microscope (SEM) analyses were employed. The results revealed that the surface area of the porous silicon carbide ceramics decreases with increased heat treatment temperature and carbon content at the $2^{nd}$ heat treatment stage. The addition of carbon to the ceramic slurry, which was composed of phenol resin and silicon powder, enhanced the direct carbonization reaction of silicon. This is ascribed to a consequent decrease of the wetting angles of carbon to silicon with increasing heat treatment temperature.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1993년도 춘계학술발표회
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• pp.19-19
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• 1993

• 한국자기학회지
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• 제24권3호
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• pp.86-89
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• 2014

이방성 희토류 본드자석은 자성분말과 유기 바인더로 구성되며 본드자석 내에서 유기 바인더는 분말의 배향을 유리하게 하는 역할을 한다. 유기 바인더는 고분자 수지, 활제, 경화제, 커플링제 등으로 구성되며 자성분말에 적합한 유기 바인더를 제조하기 위해 본 연구에서는 다양한 성분을 선정하여 유기 바인더를 제조하였고 구성비 및 첨가량을 조절하여 이를 본드자석에 적용하였다. 특성평가를 통해 자기특성 및 기계적 특성을 측정하였고 이로부터 본드자석에 적합한 유기 바인더의 성분 및 비율을 확인하였다.

• ETRI Journal
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• 제35권6호
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• pp.1152-1155
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• 2013

A cost-effective and simple solder on pad (SoP) process is proposed for a fine-pitch microbump interconnection. A novel solder bump maker (SBM) material is applied to form a 60-${\mu}m$ pitch SoP. SBM, which is composed of ternary Sn3.0Ag0.5Cu (SAC305) solder powder and a polymer resin, is a paste material used to perform a fine-pitch SoP through a screen printing method. By optimizing the volumetric ratio of the resin, deoxidizing agent, and SAC305 solder powder, the oxide layers on the solder powder and Cu pads are successfully removed during the bumping process without additional treatment or equipment. Test vehicles with a daisy chain pattern are fabricated to develop the fine-pitch SoP process and evaluate the fine-pitch interconnection. The fabricated Si chip has 6,724 bumps with a 45-${\mu}m$ diameter and 60-${\mu}m$ pitch. The chip is flip chip bonded with a Si substrate using an underfill material with fluxing features. Using the fluxing underfill material is advantageous since it eliminates the flux cleaning process and capillary flow process of the underfill. The optimized bonding process is validated through an electrical characterization of the daisy chain pattern. This work is the first report on a successful operation of a fine-pitch SoP and microbump interconnection using a screen printing process.

• 한국가구학회지
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• 제14권2호
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• pp.1-12
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• 2003

This study was carried out to determine the mechanical and physical properties of particle boards glued with condensed tannin (Wattle Tannin) powder that was single-molecule phenolic compounds like powdered phenolic resin. Our findings are; 1) It is necessary to spray water on the chip surfaces for effective application of powdered -form tannin resin. It shows that the best and optimum mat moisture increase is 14% of water spray on the surface of chips for developing PB properties. 2) In general, for both liquid and powdered tannin adhesives, their physical and mechanical properties has been proportional to the increase of resin level. But, the most efficient addition ratio is 16% of resin on dry basis. Specially, it is found that the resin level influences on the amount of free formaldehyde emission. The higher the resin level is, the lower the emission is. These phenomena seem to result from the increase of hexamine or formaline in the adhesives used as a hardener, that reduce the free-formaldehyde amount by reaction of tannin of poly-molecule and water. 3) The optimum condition for manufacturing PBs is the condition of hexamine of 5% and formaline of 6% in mechanical and physical properties. Hexamine is superior to formaline in mechanical and physical properties along with the control of the free formaldehyde emission amount. The result of NaOH's addition is insignificant in all experiments of both mechanical and physical properties.

• Journal of the Korean Wood Science and Technology
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• 제27권1호
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• pp.72-78
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• 1999

요소 멜라민수지의 조성에 의한 속경화의 가능성, 경화촉진제의 첨가에 의한 경화촉진 효과 및 접착성능에 대하여 검토하였다. 수지조성과 동시반응에 의해 제조한 UMF 수지의 겔화성과의 관계는 요소(멜라민/요소 몰비=0.2)에 대한 포롬알데히드의 몰비가 증가할수록 겔화시간이 빨라졌다. 그러나, 요소에 대한 포름알데히드의 몰비가 2.5이상에서는 수지중의 유리포름알데히드량이 KS기준에 합격하지 못하므로 속경화를 위해 수지 합성시 포름알데히드의 첨가량을 높이는 것은 어려울 것으로 생각된다. 또한, 요소에 대한 포름알데히드의 몰비를 3.4로 고정한 UMF수지에 있어서 요소에 대한 멜라민의 몰비가 0.3에서 0.6으로 증가할 수록 수지의 겔화시간은 다소 단축되었으나, 0.6이상에서는 다시 증가하였다. UMF수지의 겔화성과 접착강도는 경화제로서 염화암모늄과 p-툴루맨설폰산, 증량제로서 소액분과 콘글루텐의 병용에 의해 크게 향상되었다.

• Journal of the Korean Wood Science and Technology
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• 제35권5호
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• pp.58-66
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• 2007

The objective of this research was to develop environment-friendly adhesives for face fancy veneer bonding of engineered flooring. Urea-formaldehyde (UF)-tannin and melamine-formaldehyde (MF)/PVAc hybrid resin were used to replace UF resin in the formaldehyde-based resin system in order to reduce formaldehyde and volatile organic compound (VOC) emissions from the adhesives used between plywoods and fancy veneers. Wattle tannin powder (5 wt%) was added to UF resin and PVAc (30 wt%) to MF resin. These adhesive systems showed better bonding than commercial UF resin with a similar level of wood penetration. The initial adhesion strength was sufficient to be maintained within the optimum initial tack range. The standard formaldehyde emission test (desiccator method) and VOC analyzer were used to determine the formaldehyde and VOC emissions from engineered flooring bonded with commercial UF resin, UF-tannin and MF/PVAc hybrid resin. By desiccator method, the formaldehyde emission level of UF resin showed the highest but was reduced by replacing with UF-tannin and MF/PVAc hybrid resin. MF/PVAc hybrid satisfied the $E_1$ grade (below $1.5mg/{\ell}$). VOC emission results by VOC analyzer were similar with the formaldehyde emission results. TVOC emission was in the following order: UF > UF-tannin > MF/PVAc hybrid resin.

• 폴리머
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• 제27권5호
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• pp.493-501
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• 2003

의치상 레진 (틀니)의 기본 물질로 사용되는 폴리(메틸 메타아크릴레이트) (PMMA) 입자를 폴리(비닐 알코올) (PVAL)을 안정제로 사용하여 현탁중합법으로 중합하였고, PVAL 농도와 교반속도, 공단량체의 도입에 따른 PMMA의 입자 크기 변화 및 분자량의 변화를 관찰하였다. 또한 합성된 PMMA 수지와 메틸 메타아크릴레이트 단량체를 이용하여 고체/액체 비 (P/L ratio)를 2:1 로 하여 병상물을 제조하고, 일정한 가압성형 조건하에서 제작된 시편으로 수지의 입자 크기 및 분자량에 따른 PMMA에 기초한 틀니용 수지의 기계적 물성 변화를 관찰하였다. 그 결과 평균입자 크기가 100 $\mu$m 이하에서는 분자량이 커질수록 기계적 물성이 높게 나타났으며, 그 이상인 영역에서는 분자량에 상관없이 입자 크기가 증가할수록 기계적 물성의 저하 현상이 관찰되었다. 아울러 중합시 교반속도와 PVAL의 농도를 조절하여 크기와 분자량을 조절 가능하였는데, P/L 부피비가 2인 조건에서 제조된 열경화성 틀니용 수지로 이용되는 입자의 평균크기는 100 $\mu$m 정도가 적절하며, 분자량은 3.0${\times}$$10^{5}$ 전후가 적절함을 알 수 있었다.다.

• Carbon letters
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• 제10권2호
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• pp.94-96
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• 2009

[ $C_f/C-Cu$ ]composites were fabricated by infiltrating molten Cu into different $C_f/C$ preforms prepared by chemical vapor infiltration, resin impregnation and carbonization. The microstructure and properties of the composites were investigated. The results show that Cu in the composites filled the pores and showed network-like distribution. Compared with homemade J204 brush material and certain grade pantograph slider from abroad, the composites have higher flexural strength and better electrical conductivity. The friction and wear properties of the composites are better than that of J204, and closed to that of the abroad material.

• Carbon letters
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• 제10권2호
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• pp.97-100
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• 2009

In this work, effects of carbon matrix on sliding friction and wear behavior of four kinds of C/C have been investigated against 40 Cr steel ring mate. Composite A with rough lamination carbon matrix (RL) shows the highest volume loss and coefficient of friction, while composite D with smooth lamination/resin carbon matrix (SL/RC) shows the lowest volume loss. The worn surface of composite A appears smooth, whereas that of composite C with smooth lamination carbon (SL) appears rough. The worn surface of composite D appears smooth under low load but rough under high load. Atomic force microscope images show that the size of wear particles on the worn surface is also dependent on the carbon matrix.