• 한국환경복원기술학회지
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• 제12권2호
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• pp.1-9
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• 2009

Due to the increase of carbon dioxide in the atmosphere and global warming, the importance of forest ecosystems, as a place of carbon accumulation and emission, has received a great amount of recognition lately. This study was performed to help understand and provide the current status of carbon cycle in the pinus densiflora stand, Korea. The samples were collected from average 35-years-old Pinus densifiora rands in Gongju, Youngdong, Chungsan, Muju, Mupung, and Jangsu regions. Total thirty aboveground sample trees were cut, and ten roots were sampled, and soil samples were collected. Average carbon concentrations in foliage, branch, stem bark, stem wood, and root were 55.7%, 56.0%, 56.0%, 57.3%, and 56.5%, respectively. Carbon content was estimated by the model $Wt=aD^b$ where Wt is oven-dry weight in kg and D is DBH in cm. Total carbon content (aboveground and root) was 42.39tonC/ha in the Pinus densiflora stand. The proportion of each tree component to total carbon content was high in order of stemwood, root, branch, stem bark, and foliage. Total net primary production (aboveground and root) was estimated at 6.51tonC/ha/yr in Pinus densiflora stand. The proportion of each tree component to total net primary carbon content was high in order of sternwood, root, branch, foliage and stembark. Soil carbon contents in the study sites was 43.51tonC/ha at 0-50cm soil depth.

• 콘크리트학회논문집
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• 제27권6호
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• pp.695-703
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• 2015

콘크리트용 화학혼화제의 인수검사 시험법에 대한 국내외 기준을 살펴보고, 한국도로공사에서 활용 중인 고형분량을 대상으로 다자비교시험에 의한 통계분석을 통하여 시험법의 신뢰성을 검증하였다. 또한 FT-IR을 활용하여 다성분 조성 화학혼화제의 기기분석 효용성을 검증하였다. 시험결과의 이상치를 검정하는 Cochran, Grubbs 및 Dickson의 Q 검정을 실시하였으며, KS A ISO 5725-2의 절차에 따른 재현표준편차 및 반복표준편차는 각각 0.25 및 0.09%으로 나타나 시험방법의 신뢰성을 확인할 수 있었다. 또한 혼화제 시료상태에 따라 FT-IR 특성피크가 큰 차이를 나타내므로 건조시료에 의한 관리가 필요하였으나, 2종 이상 원료가 포함된 다성분 혼화제의 FT-IR 특성피크는 큰 차이가 없어 기기분석의 효용성을 확인할 수 없었다.

• Advances in concrete construction
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• 제9권5호
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• pp.449-457
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• 2020

The influence of subsequent curing on the performance of fly ash contained mortar under steam curing was studied. Mortar samples incorporated with different content (0%, 20%, 50% and 70%) of Class F fly ash under five typical subsequent curing conditions, including standard curing (ZS), water curing(ZW) under 25℃, oven-dry curing (ZD) under 60℃, frozen curing (ZF) under -10℃, and nature curing (ZN) exposed to outdoor environment were implemented. The unsteady chloride diffusion coefficient was measured by rapid chloride migration test (RCM) to analyze the influence of subsequent curing condition on the resistance to chloride penetration of fly ash contained mortar under steam curing. The compressive strength was measured to analyze the mechanical properties. Furthermore, the open porosity, mercury intrusion porosimetry (MIP), x-ray diffraction (XRD) and thermogravimetric analysis (TGA) were examined to investigate the pore characteristics and phase composition of mortar. The results indicate that the resistance to chloride ingress and compressive strength of steam-cured mortar decline with the increase of fly ash incorporated, regardless of the subsequent curing condition. Compared to ZS, ZD and ZF lead to poor resistance to chloride penetration, while ZW and ZN show better performance. Interestingly, under different fly ash contents, the declining order of compressive strength remains ZS>ZW>ZN>ZD>ZF. When the fly ash content is blow 50%, the open porosity grows with increase of fly ash, regardless of the curing conditions are diverse. However, if the replacement amount of fly ash exceeds a certain high proportion (70%), the value of open porosity tends to decrease. Moreover, the main phase composition of the mortar hydration products is similar under different curing conditions, but the declining order of the C-S-H gels and ettringite content is ZS>ZD>ZF. The addition of fly ash could increase the amount of harmless pores at early age.

• Asian-Australasian Journal of Animal Sciences
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• 제14권11호
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• pp.1564-1567
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• 2001

Hydrolysis of plant protein to non-protein nitrogen (N) or ammonia can reduce quality of silage crops. Heating or non-enzymatic browning is a treatment to inhibit this hydrolysis. This experiment was conducted to examine the effects of pre-heated soybean meal and molasses on the fermentation quality of napiergrass silage. The initial growth of napiergrass was harvested at 85 days of age and immediately chopped into about 1 cm length. About 700 g of the grass was ensiled into a laboratory silo (1.0 liter polyethylene container) and incubated for 30 days at room temperature ($28^{\circ}C$). No additives (control), molasses, soybean meal and molasses + soybean meal treatments were prepared. All additives were non-heated or heated in an oven at $150^{\circ}C$ for 30 minutes before ensiling. Molasses was added at 3% on the fresh weight basis and soybean meal was added at 0.5% N, respectively. After opening the silo, pH, total nitrogen (TN), volatile basic nitrogen (VBN), lactic acid (LA), acetic acid (AA), butyric acid (BA) and dry matter (DM) contents were determined. The data were analyzed statistically by analysis of variance. Compared with control, molasses addition significantly decreased pH value, VBN/TN, AA and BA and increased LA production. Soybean meal addition significantly increased TN and VBN/TN of silage. Both molasses and soybean meal addition significantly reduced pH value, AA, and BA and increased DM and LA contents of silage. The heating of additives was only effective to reduce VBN/TN production compared with non-heated additives in soybean meal and soybean meal with molasses addition.

• Journal of the Korean Wood Science and Technology
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• 제43권4호
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• pp.429-437
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• 2015

아세틸화처리는 목재의 치수안정성을 높이는 방법으로 알려졌다. 기상처리보다는 액상처리가 중량증가율이 높기 때문에 더 많이 사용된다. 국내산 소나무재와 잣나무재를 액상 아세틸화처리하여 밀도, 휨강도, 치수안정성 등 물리적 성질에 미치는 효과를 조사하였다. 아세틸화처리에 의한 소나무와 잣나무 시편의 중량은 각각 평균 10.4%와 9.2% 증가하였으며, 전건밀도는 각각 평균 6.9%와 4.6% 증가하였다. 소나무와 잣나무 모두 휨파괴계수(MOR)와 휨탄성계수(MOE), 동탄성계수(DMOE)의 변화는 없었다. 아세틸화처리 후 목재시료의 평균 항흡습률(PRH)은 소나무와 잣나무가 각각 20.6%와 13.8% 이었다. 평균 항흡수율(PRA)은 소나무와 잣나무가 각각 20.0%와 8.5%였다. 따라서 아세틸화처리에 의해 소나무의 치수안정성이 향상된 결과를 얻었다.

• 펄프종이기술
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• 제34권3호
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• pp.17-24
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• 2002

An unsteady-state moisture diffusion through cellulosic fibers in paper was characterized from the moisture sorption experiment and the mathematical modeling. The sorption experiment was conducted by exposing thin dry paper specimens to a constant temperature-humidity environment. Oven dried blotting papers and filter papers were used as test samples and the gains of their weights were constantly monitored and recorded as a function of sorption time. For a mathematical approach, the moisture transport was assumed to be an one-dimensional diffusion in thickness direction through the geometrically symmetric structure of paper. The model was asymptotically simplified with a short-term approximation. It gave us a new insight into the moisture uptake phenomena as a function of square root of sorption time. The fiber-phase moisture diffusivities(FPMD) of paper samples were then determined by correlating the experimental data with the unsteady-state diffusion model obtained. Their values were found to be on the order of magnitude of $10^{-6}-10^{-7}cm^2$/min., which were equivalent to the hypothetical effective diffusion coefficients at the limit of zero porosity. The moisture sorption curve predicted from the model fairly agreed with that obtained from the experiment at some limited initial stages of the moisture uptake process. The FPMD value of paper significantly varied depending upon the current moisture content of paper. The mean FPMD was about 0.7-0.8 times as large as the short-term approximated FPMD.

• 공업화학
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• 제24권6호
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• pp.616-620
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• 2013

본 연구에서는 자원 재활용-에너지에 바탕을 둔 돈분, 계분, 혼합물의 연소특성에 대하여 고찰하였다. 시험편은 건조 오븐을 이용하여 항량까지 건조시킨 후에, 콘칼로리미터(ISO 5660-1)를 이용하여 연소성질을 시험하였다. 그 결과 돈분의 최대유효연소열(78.72 MJ/kg)은 계분(69.41 MJ/kg)과 비교하여 탄화수소의 많은 양 때문에 비교적 증가했다. 또한 돈분의 $CO_2$ 발생속도(0.1959 g/s)와 총연기발생률($419m^2/m^2$)도 각각에 대하여 계분보다 증가하였다. 반면에 계분의 CO 발생량(0.0996 kg/kg)과 CO 발생속도(0.0034 g/s)는 계분이 함유하고 있는 많은 무기물 함량 때문에 각각 돈분보다 높았다. 따라서 높은 연소 에너지는 탄화수소 함량에 의존하여 발생되는 것으로 판단된다.

• 한국지반공학회지:지반
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• 제12권1호
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• pp.21-34
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• 1996

이 논문은 일련의 실내시험을 통해 얻어진 삼척 유기질토의 공학적 특성을 제시한 것이다. 액성한계는 시료의 조제방법에 따라 그 값이 현저히 달라진다는 사실을 알게 되었는데 자연상태로 시험한 값이 노건조시켜 얻어진 값보다 1.5내지 4배나 컸다. 유기질토의 응력변형특성은 변형의 증가에 따라 응력이 점진적으로 증가하는 경향을 보였다. 즉 변형율 20%의 강도가 한국산업규격에 규정된 변형을 15%의 강도보다 더 크다는 것을 알 수 있었다. 또한 유기질토의 강도증가율(0.43~0.65)은 점토에 비해 현저히 크다는 사실도 알 수 있었다. 압밀시험 결과 연직 및 수평방향의 투수계수는 거의 같으나 교란시에는 연직방향의 1/2~1/6로 감소된다는 사실도 알게 되었다. 또한 2차 압밀계수는 유기물함량과 함수비가 많을수록 커지며 유기물함량 15%를 기점으로 하여 그 이하에서는 변화폭이 완만하나 그 이상에서는 큰 변화폭을 보인다.

• Journal of Microbiology and Biotechnology
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• 제24권11호
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• pp.1559-1565
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• 2014

Cellulase and xylanase are main hydrolysis enzymes for the degradation of cellulosic and hemicellulosic biomass, respectively. In this study, our aim was to develop and test the efficacy of a rapid, high-throughput method to screen hydrolytic-enzyme-producing microbes. To accomplish this, we modified the 3,5-dinitrosalicylic acid (DNS) method for microwell plate-based screening. Targeted microbial samples were initially cultured on agar plates with both cellulose and xylan as substrates. Then, isolated colonies were subcultured in broth media containing yeast extract and either cellulose or xylan. The supernatants of the culture broth were tested with our modified DNS screening method in a 96-microwell plate, with a $200{\mu}l$ total reaction volume. In addition, the stability and reliability of glucose and xylose standards, which were used to determine the enzymatic activity, were studied at $100^{\circ}C$ for different time intervals in a dry oven. It was concluded that the minimum incubation time required for stable color development of the standard solution is 20 min. With this technique, we successfully screened 21 and 31 cellulase- and xylanase-producing strains, respectively, in a single experimental trial. Among the identified strains, 19 showed both cellulose and xylan hydrolyzing activities. These microbes can be applied to bioethanol production from cellulosic and hemicellulosic biomass.

• 임산에너지
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• 제22권2호
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• pp.54-59
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• 2003

최근 들어 북미와 유럽에서는 고밀화한 목질펠릿연료가 재생가능하며 카본뉴트럴한 바이오매스 에너지로서 널리 사용되고 있다. 본 연구에서는 현사시 톱밥의 고밀화를 통한 고형연료화에 관하여 연구하였다. 현사시 품종의 연료적 가치를 평가하기 위하여 열량 및 원소 분석을 수행하였다. 고밀화를 위하여 열압공정을 채택하였으며, 압밀화는 100∼180℃, 250∼1000 kgf/㎠, 2.5∼10분의 조건으로 행하였다. 고밀화연료의 특성은 밀도와 미세분 발생량으로 평가하였다. 목표치로서 고밀화연료의 전건밀도는 1.2 g/㎠ 이상, 5분간 진탕 후의 미세분 발생량은 0.5% 이하로 설정하였다. 목표 밀도와 목표미세분을 만족하기 위해서는 160℃ 이상의 압체온도가 요구되었다. 이 때의 압체압력은 750 kgf/㎠ 이상이 효과적이었다 180℃에서 1000 kgf/㎠으로 5분 이상의 압체가 고밀화연료 제조에 가장 적절한 조건으로 밝혀졌다.