• Journal of the Korean Wood Science and Technology
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• v.37 no.4
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• pp.293-299
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• 2009

In manufacturing the crack-free carbonized boards using fiberboards, shrinking ratio, weight loss and density variation of carbonized boards at each carbonization temperature were investigated. Fiberboards with thickness of 3, 4.5, 6, and 18 mm were carbonized while pressed with pressure plates at different temperature from $400^{\circ}C$ to $1,000^{\circ}C$ using a ordinary laboratory furnace. Either of crack or twist was not observed in fiberboards by adapting the pressing carbonization method. The ratios of shrinkage of length, width, and thickness were 10~25%, 12~25%, and 28~48%, respectively, and shrinkage ratio of thickness was higher than those of length and width with increasing the carbonization temperature. Weight loss tended to increase with increasing the carbonization temperature, but low correlation between weight loss in thickness of fiberboards and carbonization temperature was observed. Density of 3 mm carbonized hardboard had the highest value and it tended to increase with increasing the carbonization temperature.

• Journal of the Korea Institute of Building Construction
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• v.23 no.1
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• pp.23-33
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• 2023

It is widely known that the level of fire resistance of wooden structure is determined by a charring rate or charring depth, and these are adopted for fire design. In this study, specimens of domestic larch column with a lamination wooden type were prepared and the fire resistance properties such as the charring depth, load ratio and the specific charring rate suggested by EN Code investigated. Test results showed that as expected, the weakest part was the corner of the column, so that the charring depth of the corner was deeper than the other parts of the column. For the load ratio less than 0.9, it had little effect on the charring depth.

• Journal of the Korea Institute of Building Construction
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• v.23 no.6
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• pp.761-772
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• 2023

The fire resistance design of timber structures involves calculating the residual section based on charring depth, which is then utilized in structural design. Charring depth is determined from fire-resistance test results in Korea, which currently do not account for the charring properties of the adhesive used in Glued Laminated Timber(GLT) production. This study fabricated GLT using various adhesives employed in domestic GLT production, comparing the charring properties by adhesive type and the fire resistance performance relative to the directionality of the laminated surface. Melamine demonstrated the most advantageous fire resistance performance, followed by resorcinol and polyurethane. Furthermore, it was established that the laminated section exhibited a higher charring rate, influenced by the adhesive, compared to the laminated surface, which significantly impacts the fire resistance performance.

• Fire Science and Engineering
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• v.25 no.3
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• pp.78-84
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• 2011

In this study, we have measured the charring rate of solid sawn timber as a preceding step for develop performance based fire safety design method of wood framed building structures. The follows are the summary of fire test results carried out with $400{\times}400$ mm cross-section Douglas-fir in varied of thickness and grain directions. I) When the timber thickness increase under same dimension, the charring rate decreases gradually. It is seemed the charring layer up on a thickness roles as a insulation, gives combustion delaying time to specimen. 2) The charring rates measured at different depths (10, 20, 30, 40 mm) in timber which varying thickness (20, 40, 80, 120 mm) when exposed maximum 1 hour standard fire increase by 30 mm depth, but decrease at 40 mm. It is seemed the minimum charr layer should be 30 mm for having role of insulation. 3) The charring rate of cross section surface (direction of perpendicular to grain) was more high than that of grain direction. It can be explained by the cracks and gaps from greater charr contraction made more heat flux incident into timber.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.65-68
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• 2007

저온 플라즈마 기술을 이용하면 오스테나이트계 스테인리스강의 내식성과 표면경도를 동시에 증가 시킬 수 있다. 여러 가지 처리방법 중 질탄화와 2-step 공정으로 처리한 AISI304L강의 표면을 분석하였다. 처리한 모든 시편의 표면은 expanded austenite(${\gamma}_N$)이 형성되었고, 표면 경도도 모재보다 약 4배 이상 증가 하였다. 저온플라즈마 질탄화 공정의 경우 경화층의 두께가 최대 15 ${\mu}m$밖에 형성되지 않았지만 2-step공정의 경우 질탄화 공정보다 짧은 시간으로 약 2배의 경화층을 얻을 수 있었다. 두 가지 공정 모두 온도와 시간이 증가할수록 경화층의 두께가 두꺼워졌지만, 과도하게 높은 온도와 긴 공정시간은 석출물을 형성 시켰다. 석출물이 형성되지 않은 시편의 경우 내식성이 증가하였다.

• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.251-257
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• 2014

For new use development of miscanthus sinensis var. purpurascens, which investigated properties of ceramics made from different carbonization temperature ($600{\sim}1,200^{\circ}C$) and percentage of resin impregnation(30~60%) using a mincanthus board. As the carbonization temperature increased, the density, thickness shrinkage, linear shrinkage, weight loss were increased. As the percentage of resin impregnation increased, the density, linear shrinkage and weight loss were increased. On the other hand, thickness shrinkage decreased.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.2
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• pp.19-26
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• 1991

This study has been constructed to establish the formation of the VC layer on various steels by immersion in fused borax bath containing Fe-V powder. The result obtained from the experiment are as follows. (1) The carbide is supposed to grow on the front surface of the carbide layers by the reaction between carbide-forming elements dissolved in the fused borax and carbon atoms successively supplied through the layer from the matrix. (2) The growth rate of the carbide layers was controlled by the diffusion rate of C in the carbide layer and C content in the matrix. (3) Carbide layer formed on the surface of the specimen is VC layer and the hardness of this layer is above $H_v$ 3000.

• Journal of the Korean Wood Science and Technology
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• v.31 no.5
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• pp.80-87
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• 2003

This research was carried out to examine physical and mechanical properties of clay-woodceramics which were carbonized for 3 hours in a special furnace from 3 layers-clay-woodparticleboard made from pallet waste wood, phenol formaldehyde resin(hereafter PF, Non volatile content 52%, resin content 30%) and clay(10%, 20% and 30%). Carbonization temperature was 400℃, 600℃ and 800℃. The results are summarized as follows: 1. The higher the carbonization temperature, the higher the dimensional shrinkage and the lower the carbonization yield ratio. But the higher the clay addition, the lower the dimensional shrinkage and the higher carbonization yield ratio. 2. The higher the carbonization temperature, the higher the water absorption and the density. The higher the clay content, the higher the density. 3. The higher the carbonization temperature, the higher the bending Modulus of Rupture and bending Modulus of Elasticity.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.79-79
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• 2000

탄화규소는 그 전기적, 열적 기계적 안정성 때문에 새로운 반도체 재료로서 주목받고 있는 물질이다. 탄화규소를 이용하여 전자소자를 제조하기 위해서는 ohmic 접촉과 Schottky 접촉을 형성하는 전극물질의 개발이 선행되어야 하며, 고온, 고주파, 고출력용 반도체 소자를 제조하기 위해서는 전극의 고온 안정성 확보가 필수적이다. 따라서 탄화규소 소자의 응용범위는 전극에 의해서 제한된다고 할 수 있다. 일반적으로 전극을 증착한 후 원하는 접촉 특성을 얻기 위해서는 열처리 과정을 거쳐야 하며 접촉의 특성이 열처리에 의해 영향을 받는 것으로 알려져 있다. 따라서 본 연구에서는 열처리가 금속/탄화규소 접촉의 특성에 미치는 영향을 알아보고자 하였으며, 이를 바탕으로 우수한 Schottky 다이오드의 제작 가능성을 타진해보고자 하였다. 유기실리콘 화합물 원료인 TEMSM(bis-trimethysilylmethane)을 사용하여 실리콘 기판위에 단결정 $eta$-Sic 박막을 증착하였다. 기판의 영향을 줄이기 위하여 $\beta$-Sic 박막의 두께가 $1.5mu extrm{m}$ 이상인 시편을 사용하였다. 전극으로는 Pt를 사용하였으며, 전극 증착은 DC magnetron sputter를 이용하였다. 전기적인 특성을 분석하기 위하여 전류-전압, 커패시턴스-전압 특성을 분석하였고, XRD와 AES를 이용하여 계면에서의 반응을 알아보았다. Hall 측정 결과 모든 $\beta$-Sic 박막은 약 2$\times$1018cm-3 정도의 도핑 농도를 갖는 n형 탄화규소임을 확인하였다. Pt/$\beta$-Sic 접촉은 열처리 전에는 ohmic 접촉 특성을 보였으나 열처리 후에는 Schottky 접촉의 특성을 나타냈다. 전기적 특성 분석을 통하여 열처리 온도가 증가할수록 에너지 장벽의 높이가 증가하는 것을 알 수 있었다. 이상적인 Pt/$\beta$-Sic 접촉의 특성을 보이는 것은 전극 증착시 sputtering에 의하여 계면에 발생한 결함이 도너의 역할을 하여 에너지 장벽의 두께를 감소시켜 tunneling을 촉진하기 때문인 것으로 판단된다. 열처리 후 접촉 특성이 변화하는 것은 이러한 결함들의 소멸 때문으로 생각된다. AES 분석을 통하여 열처리시 Pt가 $\beta$-Sic 내부로 확산하는 것을 알 수 있었으며, 이 때 Pt가 $\beta$-Sic 와 반응하여 계면에 실리사이드가 형성됨으로써 Pt/$\beta$-Sic 계면이 보다 안정한 탄화규소 박막 내부로 이동하게 되고 계면의 결함 농도가 줄어드는 것이 접촉 특성 변화의 원인이라 할 수 있다. 열처리 온도가 증가함에 따라 계면이 점점 $\beta$-Sic 내부로 이동하여 결함농도가 낮아지기 때문에 tunneling 효과가 감소하여 에너지 장벽이 높아지게 된다. Pt를 ohmic 접촉과 Schottky 접촉 전극물질로 이용하여 제작한 Schottky 다이오드는 ohmic 접촉 형성시 Schottky 접촉에 발생하는 wputtering 손상에 의하여 좋은 정류특성을 얻지 못하였다. 따라서 chmic 접촉 전에 Schottky 접촉의 passivation이 필요한 것으로 판단된다.

• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.335-342
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• 2017

This study was carried out to explore a new application of the by-products sawdust, formed during sawing and mandarin peels which are agricultural by-products. The boards were manufactured by mixing the sawdust and mandarin peels at different mixing ratio and density. The boards were then converted to ceramics by various percentage of resin impregnation and at different carbonization temperatures. As the percentage of resin impregnation increased, the weight loss was decreased; on the other hand, density, linear shrinkage and thickness shrinkage increased. As the carbonization temperature increased, the weight loss was increased and linear thickness shrinkage increased to $1000^{\circ}C$ and the subsequent increase was insufficient. As the percentage of mandarin peels addition increased, the weight loss, linear shrinkage and thickness shrinkage was decreased.