• Journal of the Korean Wood Science and Technology
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• 제22권2호
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• pp.30-36
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• 1994

Steam explosion process is one of the most efficient, pretreatment method for the utilization of lignocellulosic biomass. The carbxymethyl-cellulose(CMC) was prepared with steam exploded wood(EXW), pine(Pinus densiflora) and oak(Quercus mongolica), by standard method using isopropyl alcohol and monochloroacetic acid. The range of water solubility of carboxymethylated pine exploded wood was 45.2~66.8 % and those of oak was 60.7~84.7 %. The degree of substitution(D.S) of carboxymethylated pine exploded wood was 0.11~0.33 and oak exploded wood was 0.48~0.76. The color of carboxymethylated pine and oak exploded wood was brown-black. When carboxymethylated EXW was purified by sulfuric acid, the yield of carboxymethylated wood was lower than non-treated one. However, the color was still brown-black although after delignification. In carboxymethylated EXM prepared after delignification, the water solubility and degree of substitution(D.S) of pine were 81.4~95.9 % and 0.71~0.79, and those of oak were 76.2~89.5 % and 0.79~1.05. The values were higher than non-treated. The degree of substitution of purified carboxymethylated wood prepared with delignified EXM, pine and oak were 0.50~0.71 and 0.70~0.88. The color of carboxymethylated wood was white. In carboxymethylated wood preparde after delignification of EXM, swelling ratio and water retention value of pine were 95.9~96.5 and 580.0~751.2, those of oak were 76.2~89.5 and 124.3~307.6.

• Journal of the Korean Wood Science and Technology
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• 제17권2호
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• pp.65-73
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• 1989

Steam explosion process is an efficient pretreatment method for sparating and utilizing wood main components has attracted attention in utilization of ligno-cellulosic biomass. In order to obtain the effective pretreatment condition. this study was made explosion apparatus. examined the composition. extraction of exploded wood. Wood chips of pine(Pinus densiflora oak (Quercus serrata) and birch wood (Belula platyphylla var. japonica) were treated with a high pressure steam(20-30 kg/$cm^2$, 2-6 minutes). The results can be summarized as follow; In analysis of exploded wood(EXW). It was found arabinose residues rapidly decreased with increasing of steaming time and pressure. Extractives of EXW with sodium hydroxide increased with increasing of steaming-time and- pressure especially extractives 1% sodium hydroxide has higher than other extracted method extractives of hard wood(oak, birch) has higher than pine wood. In EXW extracted with sodium hydroxide and methanol lignin was partially delignified alkali extraction was more delignified than methanol extraction hardwood than pine wood.

• Journal of the Korean Wood Science and Technology
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• 제45권2호
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• pp.182-194
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• 2017

The optimum alkali pretreatment parameters (reaction time, reaction temperature and potassium hydroxide concentration) for facilitate the conversion into fermentable sugar (glucose) from steam exploded (severity log Ro 2.45) barley husk were determined using Response Surface Methodology (RSM) based on a factorial Central Composite Design (CCD). The prediction of the response was carried out by a second-order polynomial model and regression analysis revealed that more than 88% of the variation can be explained by the models. The optimum conditions for maximum cellulose content were determined to be 201 min reaction time, $124^{\circ}C$ reaction temperature and 0.9% potassium hydroxide concentration. This data shows that the actual value obtained was similar to the predicted value calculated from the model. The pretreated barley husk using acid hydrolysis resulted in a glucose conversion of 94.6%. This research of steam explosion and alkali pretreatment was a promising method to improve cellulose-rich residue for lignocellulosic biomass.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.395-396
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• 2004

• Journal of the Korean Wood Science and Technology
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• 제39권4호
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• pp.326-332
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• 2011

국산 산공재 중 구조적 특징이 목재흡음에 적합하다고 생각되는 백합나무 목재 횡단면의 흡음성능과 기체투과성의 방사방향 변동과 폭쇄처리 영향을 관찰하고자 무처리와 폭쇄처리 목재원반에서 방사방향위치가 다른 원형시험편을 채취하여 전달함수법과 CFP (capillary flow porometry)법으로 흡음율과 기체투과성을 각각 측정, 비교하였다. 측정주파수범위에서 폭쇄처리 횡단면의 흡음율이 무처리재보다 높은 흡음성능을 나타내었으며 횡단면에서는 대경 도관이 다수 존재하여 다공질형흡음에 유용한 연속된 모세관이 다량 존재하는 사실을 확인할 수 있었다. 방사방향으로는 심재부위에서 채취한 시험편보다 변재부위에서 채취한 시험편의 흡음계수가 높은 흡음율을 나타내었으며, 기체투과성도 변재부위가 심재부위보다 높은 수치를 나타내었다.

• Journal of the Korean Wood Science and Technology
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• 제28권3호
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• pp.9-13
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• 2000

본 연구는 해마다 100만 톤 이상이 생산되는 국내산 왕겨를 이용하여 왕겨보드를 제조함에 있어, 무처리 왕겨로 제조한 왕겨보드의 기계적 성질의 단점을 보완하기 위하여 왕겨를 전처리함으로써 그 물리 기계적 성질을 개선하기 위해 실시되었다. 연구결과를 요약하면, 무처리, 증자처리 및 가성소다로 알칼리처리한 왕겨보드보다 폭쇄처리한 왕겨보드가 휨강도 및 박리강도가 더 높았으며, 이때 적정 폭쇄처리 조건은 압력 20kgf/$cm^2$, 시간 1분과 압력 25kgf/$cm^2$, 1분이었다. 무처리 왕겨보드의 경우 휨강도, 박리강도 모두 KS를 만족시키지 못한 반면, 폭쇄처리 왕겨 보드의 경우 KS PB 18.0형의 기준을 모두 만족시켰으며, PB 대조구와 비교할 때 동등한 강도를 보였다. 기타 왕겨 전처리의 경우에 있어서도 가성소다처리보다는 증자처리가 왕겨보드의 강도를 향상시키는 것으로 나타났다.

• Journal of the Korean Wood Science and Technology
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• 제24권3호
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• pp.45-50
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• 1996

Wood chips of oak(Quercus mongolica) and larch(Larix leptolepis) were treated with low pressure steaming explosion. Main components of exploded wood were separated with hot water and methanol extraction. Crude lignin separated from those extractives were purified and those chemical characteristics were investigated. And also, lignin adhesive was prepared from crude lignin and studied those chemical characteristics. The results can be summarized as follows ; 1. The purified lignin by Bj$\ddot{o}$kman's method from crude lignin is about 30% in exploded oak wood and is about 11% in exploded larch wood as a low amount. 2. The phenolic hydroxyl groups in the purified lignins are little higher than those of MWL and molecular weight distributions of the purified lignins are some lower than that of MWL. 3. Alkaline nitrobenzene oxidation products are very low in the clude lignin but those are increased in the purified lignin 4. The gravity of lignin resins(1.15 and 1.13) are a little lower than that of phenol resin(1.16) and the compressive shearing strength of lignin resins are higher than those of phenol resin.

• Nuclear Engineering and Technology
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• 제48권1호
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• pp.218-227
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• 2016

Background: Steam explosions may occur in nuclear power plants by molten fuel-coolant interactions when the external reactor vessel cooling strategy fails. Since this phenomenon can threaten structural barriers as well as major components, extensive integrity assessment research is necessary to ensure their safety. Method: In this study, the influence of yield criteria was investigated to predict the failure of a reactor cavity under a typical postulated condition through detailed parametric finite element analyses. Further analyses using a geometrically simplified equivalent model with homogeneous concrete properties were also performed to examine its effectiveness as an alternative to the detailed reinforcement concrete model. Results: By comparing finite element analysis results such as cracking, crushing, stresses, and displacements, the Willam-Warnke model was derived for practical use, and failure criteria applicable to the reactor cavity under the severe accident condition were discussed. Conclusion: It was proved that the reactor cavity sustained its intended function as a barrier to avoid release of radioactive materials, irrespective of the different yield criteria that were adopted. In addition, from a conservative viewpoint, it seems possible to employ the simplified equivalent model to determine the damage extent and weakest points during the preliminary evaluation stage.

• Preventive Nutrition and Food Science
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• 제7권1호
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• pp.78-87
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• 2002

This study investigated the production of insoluble dietary fiber using forest waste and the dietary effect of manufactured insoluble fiber on physiological function in rat fed high cholesterol duets. Insoluble dietary fiber was prepared from the wood chips of oak (Quercus mongolica). The best condition for steam-explosion treatment for the preparation of insonuble dietary fiber was 25 kg/cm$^3$pressure for 6 minutes. In the chemical analysis of insoluble dietary fiber pretreated by 1% sodium hydroxide solution with steam-exploded wood, $\alpha$-cellulose content was 61.7% in the insoluble dietary fiber which contained 7.6% residual lignin. In order to compare insoluble dietary fiber with commercial $\alpha$-cellulose of physiological function, Sprague-Dawley male rats weighing 100$\pm$10 g were randomly assigned to one normal diet and five high cholesterol diet containing 1% cholesterol. The high cholesterol diet groups were classified as fiber free diet (FF group), 5% commercial $\alpha$-cellulose diet (5C group), 10% commercial $\alpha$-cellulose (l0C group), 5% insoluble dietary fiber dict (5M group), and 10% insoluble dietary fiber (10M group). The rats were fed ad libidum for 4 weeks. Food intake, weights gain, and food efficiency ratio in high cholesterol groups were higher than those of normal group, but there were no significant differences between the experimental groups. There were not any significant differences in the weights of livers, kidneys and small intestine of insoluble dietary fiber supplemented groups, but weight of cecum in all insolube dietary fiber group were significantly higher than those of FF group. A gstrointestinal transit time was decreased by supplementation of insoluble dietary fiber. Weight and water contents of feces in the insoluble dietary fiber supplemented groups were significantly higher than those of the FF group. There were not any significant differences in the activities of the glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT) between the experimental groups. In conclusion, the manufactured insoluble dietary fiber and commercial insoluble fiber have the same physiological effects. The preparation method of the insoluble dietary fiber from the oak chips suited its purpose.

• Nuclear Engineering and Technology
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• 제53권10호
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• pp.3264-3274
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• 2021

In a severe accident of light water reactor (LWR), molten core material (corium) can be released into the wet cavity, and a fuel-coolant interaction (FCI) can occur. The molten jet with high speed is broken and fragmented into small debris, which may cause a steam explosion or a molten core concrete interaction (MCCI). Since the premixing stage where the jet breakup occurs has a large impact on the severe accident progression, the understanding and evaluation of the jet breakup phenomenon are highly important. Therefore, in this study, the jet breakup simulations were performed using the Smoothed Particle Hydrodynamics (SPH) method which is a particle-based Lagrangian numerical method. For the multi-fluid system, the normalized density approach and improved surface tension model (CSF) were applied to the in-house SPH code (single GPU-based SOPHIA code) to improve the calculation accuracy at the interface of fluids. The jet breakup simulations were conducted in two cases: (1) jet breakup without structures, and (2) jet breakup with structures (control rod guide tubes). The penetration depth of the jet and jet breakup length were compared with those of the reference experiments, and these SPH simulation results are qualitatively and quantitatively consistent with the experiments.