• Journal of the Korean Wood Science and Technology
• /
• 제49권4호
• /
• pp.287-298
• /
• 2021

Torch ginger (Etlingera elatior Jack) is a potential source of lignocellulose material for various derivative products. This study aims to determine the chemical components, ratio of syringyl to guaiacyl units (S/G) in lignin, and crystallinity of the biomass of torch ginger. The effects of soda pulping on the chemical characteristics of torch ginger pulp were also studied. Pulping of the chips was conducted with active alkali of 15%, 20%, and 25% and a Liquor-to-Wood (L/W) ratio of 4:1, 5:1, and 6:1. The impregnation and pulping times at maximum temperature (170℃) were 120 and 90 min, respectively. To assess the effect of treatments on the properties of pulping, a two-factorial experimental design was applied. Results showed that the content of α-cellulose and hemicellulose in the torch ginger was 48.48% and 31.50%, respectively, with an S/G ratio of 0.70 in lignin. Soda pulping changed the crystalline structure of the biomass from triclinic to monoclinic. Active alkali, L/W ratio, and interactions considerably influenced the observed responses. The degree of delignification increased with an increase in the loading of active alkali, which lead to a decrease in the kappa number of the pulp. An active alkali content of 25% and an L/W ratio of 6:1 resulted in the highest delignification selectivity with a kappa number of 2.78 and a yield of 24%. Given its cellulose content and ease of pulping, torch ginger can be a potential raw material for derivative products that require delignification as pretreatment. However, the increase in cellulose crystallinity should be considered when converting torch ginger to bioethanol.

• 한국재료학회지
• /
• 제23권1호
• /
• pp.24-30
• /
• 2013

Today, the modification of carbon foam for high performance remains a major issue in the environment and energy industries. One promising way to solve this problem is the optimization of the pore structure for desired properties as well as for efficient performance. In this study, using a sol-gel process followed by carbonization in an inert atmosphere, hollow spherical carbon foam was prepared using resorcinol and formaldehyde precursors catalyzed by 4-aminobenzoic acid; the effect of carbonization temperature and re-immersion treatment on the pore structure and characteristics of the hollow spherical carbon foam was investigated. As the carbonization temperature increased, the porosity and average pore diameter were found to decrease but the compression strength and electrical conductivity dramatically increased in the temperature range of this study ($700^{\circ}C$ to $850^{\circ}C$). The significant differences of X-ray diffraction patterns obtained from the carbon foams carbonized under different temperatures implied that the degree of crystallinity greatly affects the characteristics of the carbon form. Also, the number of re-impregnations of carbon form in the resorcinol-formaldehyde resin was varied from 1 to 10 times, followed by re-carbonization at $800^{\circ}C$ for 2 hours under argon gas flow. As the number of re-immersion treatments increased, the porosity decreased while the compression strength improved by about four times when re-impregnation was repeated 10 times. These results imply the possibility of customizing the characteristics of carbon foam by controlling the carbonization and re-immersion conditions.

• Carbon letters
• /
• 제8권4호
• /
• pp.280-284
• /
• 2007

Samples of active carbon of $1150\;m^2/g$ surface area were impregnated with ammoniacal salts of copper, chromium and silver, with and without triethylenediamine. The samples of impregnated carbon were aged at $50^{\circ}C$, with and without 90% RH (relative humidity), for a little more than one year and chemically evaluated periodically. Initially copper (II) and chromium (VI) reduced very fast in the samples in humid atmosphere to the extent of 30% and 60% respectively in four months. These values were found to be unaffected by the presence of triethylenediamine (TEDA) indicating that the chemical did not retard the reduction process of chromium (VI) and copper (II). However, in the absence of humidity the reduction of the impregnants was significantly less (10-12%, w/w) in four months. It was quite evident; therefore, that the moisture was mainly responsible for the reduction of chromium (VI) and copper (II) species in impregnated carbons. The prolonged ageing of the samples with and without triethylenediamme after four months with and without humid atmosphere showed that the extent of reduction of chromium (VI) was very low, i.e. 5-10% and of copper (II) was 2-25%. Silver is not reduced due to carbon, as it remained unchanged in concentration on storage. The impregnated carbon samples (100 g) without triethylenediamine, which were aged at room temperature for 5 years in absence of humidity and unaged when evaluated against cyanogen chloride (CNCl) at a concentration of 4 mg/L and airflow rate of 30 lpm showed a high degree of protection (80- 110 minutes).

• 공업화학
• /
• 제19권3호
• /
• pp.345-350
• /
• 2008

고분자함침콘크리트(PIC)는 물리화학적 물성뿐만 아니라 기계적 강도가 우수한 재료로서 성형된 일반 콘크리트를 변조하여 제조한다. PIC 제조공정은 성형된 공시체의 건조, 단량체의 함침, 중합공정으로 구성된다. PIC 제조공정 중 고분자 중합공정은 지금까지 주로 열 및 수중중합방법을 사용하여 콘크리트 내부의 온도구배가 크고 라디칼 생성이 억제되어 불균일한 중합을 초래하였다. 본 연구에서는 마이크로파를 이용한 중합 반응기를 제작하여 스티렌/메틸메타아크릴레이트(MMA) 1 : 1의 혼합물을 단량체로 사용한 PIC 제조의 중합공정에 사용하였다. 그 결과 열중합보다 매우 균일한 PIC를 제조할 수 있었으며, 30% 이상 중합도가 증가하였고, 공시체보다 기계적 압축강도는 600% ($800{\sim}1200kg_f/cm^2$)까지 증가하였으며, 내산성은 20% 이상 증가하였다. 또한 개시제는 1% 이하로 사용할 수 있었고 중합의 최적 조건은 400 W, 2450 MHz의 radiation 조사로 최적 온도는 $120^{\circ}C$였다.

• 공업화학
• /
• 제28권2호
• /
• pp.221-229
• /
• 2017

본 연구에서는 다양한 상용 알루미나 지지체의 수소 상온산화 반응특성을 확인하기 위하여 활성금속 Pt를 기본으로 한 촉매에 습식함침법으로 제조하였다. 제조된 촉매들은 XPS, CO-chemisorption, BET를 이용하여 특성분석을 수행하였다. 다양한 $Pt/Al_2O_3$계 촉매는 열처리 조건에 따라서 촉매를 제조할 경우 전자 전하의 이동으로 발생하는 전기음성도 특성이 Pt의 산소종을 제어하였다. Pt의 담지량이 증가함에 따라 분산도가 감소하는 이유는 Pt의 HT (Huttig Temperature)에 기인한 것으로 보인다. 또한 상온에서 제어할 수 있는 최소 수소농도는 metallic Pt가 촉매 내 70.09% 이상에서 1.0 vol%까지 수소를 제어할 수 있었다.

• Korean Journal of Acupuncture
• /
• 제24권4호
• /
• pp.99-110
• /
• 2007

Objectives : Epilepsy is one of the most common serious brain disorders that affect people of all ages, and it is characterized by recurrent unprovoked seizures. We examined whether acupuncture can reduce both the incidence of seizures and hippocampal cell death in dentate gyrus (DG) using a mouse model of kainic acid (KA)-induced epilepsy. Methods : ICR mice ($20{\sim}25$ g) were given acupuncture once a day at acupoint HT8 (sobu) bilaterally during 2 days before KA injection. After an intracerebroventricular injection of 0.1${\mu}g$ of KA, acupuncture treatment was subsequently administered once more (total 3 times), and the degree of seizure was observed for 20 min. Three hours after injection, we confirmed the neural cell death using cresyl violet staining and silver impregnation staining, and determined the expressions of c-Fos and glutamate decarboxylase (GAD)-67 using immunohistochemistry techniques in the DG. Results : KA induced epileptic seizure, neural cell death, increased c-Fos expression and decreased GAD-67 expression in the DG. Acupuncture treatment at HT8 reduced the severity of the epileptic seizure and inhibited neural cell death from KA. In addition, acupuncture normalized the expressions of c-Fos and GAD-67 in the same areas. Conclusions : These results demonstrated that acupuncture treatment at HT8 may reduce the KA-induced epileptic seizure and neural cell death in the DG possibly by normalizing c-Fos expressions and the gamma-aminobutyric acid neurons.

• 대한환경공학회지
• /
• 제22권2호
• /
• pp.203-210
• /
• 2000

탈아세틸화도와 평균분자량이 다른 키토산 3종류를 활성탄 표면에 첨착하는 방법과 그 특성에 관하여 연구하였다. 키토산 첨착활성탄은 주로 산 용액에 키토산을 용해시켜 활성탄을 침적한 후, 회전증발기에서 일정시간 교반하여 증발 건조하는 방법으로 제조하였다. 키토산을 용해하는 산 종류 및 농도, 첨착량, 교반조건의 변화에 따른 비표면적 변화, 표면상태 및 안정성을 검토하고, 키토산 첨착활성탄의 Cr(VI) 흡착특성을 조사하였다. 키토산 첨착활성탄의 제조에는 키토산을 초산용액에 용해하여 그 용액에 활성탄을 침적하고 실온에서 1시간 정도의 교반이 적절하였다. 분자량이 작은 키토산은 소량의 첨착으로도 비표면적을 크게 감소시켰고, 큰 분자량의 키토산은 10wt%까지 거의 일정하게 원래 활성탄의 비표면적을 유지하였다. 키토산은 활성탄 표면에 균일하게 물리적으로 첨착되어 있었고, 키토산 첨착활성탄은 약 pH 6 이상의 용액에서 안정하였다. Cr(VI)의 제거율은 활성탄이나 키토산 자체보다 크게 향상되었다. 이는 첨착된 키토산이 활성탄 자체의 흡착력을 향상시킨 것으로 생각되며, 약 5wt% 첨착량에서 키토산과 활성탄의 중금속 흡착기능이 효과적으로 나타남을 알았다.

• Composites Research
• /
• 제30권3호
• /
• pp.175-180
• /
• 2017

탄소섬유 강화 복합재료는 가볍고, 우수한 물성을 가지고 있기 때문에 그 수요는 급격하게 증가되고 있다. 그에 따라, 탄소섬유 강화 복합재료의 기지로 재활용이 가능한 열가소성 수지를 사용한 복합재료 연구를 많이 진행하고 있다. 본 연구에서는 재활용 PET를 이용하여 재활용 복합재료에 대한 활용성 평가를 하였다. PET는 음료수 병으로 활용되는 폐기물을 수집하여 PET 필름을 제조하는 과정을 거쳤으며, PET 필름을 제조하기 위한 성형 온도와 시간의 차이에 따른 기계적 물성을 비교하여 최적의 성형온도와 시간을 분석하였다. 이를 바탕으로 재활용 PET 필름과 탄소섬유 매트를 이용하여 CF/PET 복합재료를 최적으로 성형하기 위한 변수를 관찰하였다. 성형 조건에 따른 기계적 물성을 굴곡시험으로 확인하였고, PET 필름이 탄소섬유 매트 내에 함침 되는 정도를 단면 사진으로, 그리고 계면 성질을 층간전단강도로 평가하였다. 궁극적으로 최적의 기계적 물성을 가지는 CF/PET 복합재료를 성형하기 위한 성형 조건이 $270^{\circ}C$와 5분임을 확인했다.