• Carbon letters
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• v.12 no.3
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• pp.131-137
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• 2011

Kenaf fibers, cellulose-based natural fibers, were used as precursor for preparing kenafbased carbon fibers. The effects of carbonization temperature ($700^{\circ}C$ to $1100^{\circ}C$) and chemical pre-treatment (NaOH and $NH_4Cl$) at various concentrations on the thermal change, chemical composition and fiber morphology of kenaf-based carbon fibers were investigated. Remarkable weight loss and longitudinal shrinkage were found to occur during the thermal conversion from kenaf precursor to kenaf-based carbon fiber, depending on the carbonization temperature. It was noted that the alkali pre-treatment of kenaf with NaOH played a role in reducing the weight loss and the longitudinal shrinkage and also in increasing the carbon content of kenaf-based carbon fibers. The number and size of the cells and the fiber diameter were reduced with increasing carbonization temperature. Morphological observations implied that the micrometer-sized cells were combined or fused and then re-organized with the neighboring cells during the carbonization process. By the pre-treatment of kenaf with 10 and 15 wt% NaOH solutions and the subsequent carbonization process, the inner cells completely disappeared through the transverse direction of the kenaf fiber, resulting in the fiber densification. It was noticeable that the alkali pre-treatment of the kenaf fibers prior to carbonization contributed to the forming of kenaf-based carbon fibers.

• Journal of the Mineralogical Society of Korea
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• v.14 no.2
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• pp.85-98
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• 2001

This study deals with the petrographic examination of aggregates(ASTM C 295) which is one of the methods to diagnose the quality of aggregates for concrete artifacts. A number of examinations including size and sieve analysis, test on the coating material, description of the weathering and contamination condition, petrographic description, and qualitative and quantitative analyses on the rocks and minerals potential to alkali-aggregates reactivity are carried out to examine the quality of aggregates. Petrographic description method examined on the fluvial aggregates from Maewhacheon A, B area, Uljin-gun, Kyungnam province shows that weathering grade ranges from F(fresh) to WS(slightly weathered) and coating material and contamination are not in a harmful condition. The weight percentage of the alkali-aggregates reactive minerals or structurally unstable rocks of the aggregates from study area covers 26% and 19% of all aggregates, respectively. So it is necessary to further identify their quality through the chemical(ASTM C 289) and mortar-bar method (ASTM C 227).

• Applied Biological Chemistry
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• v.30 no.2
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• pp.133-140
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• 1987

The physicochemical properties and characteristics of potato starches which were isolated from the six varieties were investigated. The ash content of starch prepared from the Arkula showed lower than that of the other five samples. The shapes of starch granules were oval and round, and the average diameters were in the range of $25{\sim}26.9$ microns. The main constituents of the inorganic components of each starch sample were found to be phosphorus and potassium. The amylose contents of starches were between $27.2{\sim}32%$, and blue value, alkali numbers were in the range of $0.42{\sim}0.45$ and $5.8{\sim}7.7$, respectively. Amylograph data revealed that Nook Sack had the highest viscosity at all reference points. The swelling power and solubility patterns were negligible until $50^{\circ}C$, thereafter it increased rapidly.

• Journal of Ginseng Research
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• v.8 no.2
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• pp.124-134
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• 1984

Ginseng root starch, prepared by conventional method, contained crude lipid of 0.5%, crude protein of 0.4%, crude mineral of 0.17% and phosphorous of 12.5mg% as noncarbohydrate constituents. The amylose content of ginseng root starch picked in Summer (May to August) and Winter (November to March) was 32-35% and 15-20%, respectively, and it was decreased with a growing preiod of ginseng. The blue value, alkali number and ferricyanide number of the starch were 0.14-0.17, 8.50 and 0.781, respectively. The molecular weight of amylose in the starch was estimated to be 1.27-7.95${\times}$105 by means of periodate oxidation, and the degree of branching and glucose unit per segment of amylopectin were 3.50-3.53% and 28.3-28.5, respectively, The starch content of ginseng root was decreased when dried under sunlight and stored at 5$^{\circ}C$ for twenty days. In contrast, sucrose content in the root was increased from 3.8% in fresh state to 11.5% during storage at the above condition. In the other hand, starch was converted to maltose by heating at temperature above 70$^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.70-73
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• 2003

Although there has been an upcoming recognition in the repairing reinforcement and remodeling of currently existing buildings with a regard to economic and resource saving effects of buildings roughly exposed to the open air for a long-term period, followed by a number of problems with the construction business operations that support economy-oriented projects within the limits of their short-term period durability, it is true that reasonable decisions of concrete performance are insufficient owing to the lack of proper history management for those existing buildings. This research attempted to comparatively analyze the compression strength together with investigation of carbonization depth and alkali concentration according to the passage of years on the subjects of aged buildings, and to provide basic data for remodeling and/or reconstruction of future construction structures by indirectly estimating durability lifetime expectancy according to carbonization phenomenon.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.2
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• pp.73-79
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• 2008

The permanence is of great importance to library and archival paper. According to the established standardizations including ISO and ANSI, the permanence can be specified with tear strength, pH, alkali reserve and kappa number. In this study, we evaluated the permanence and durability of domestic coated and copy paper grades. Two types of coated paper grades and all kinds of copy papers which were tested in this study were satisfied with the criterion of permanence specification. However, all of the tested paper grades didn't meet the requirements of durability because of their low folding endurance.

• Preventive Nutrition and Food Science
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• v.2 no.1
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• pp.23-28
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• 1997

Physicohemical properties of corn starches isolated from non-glutinous and corn grains fol-lowing γ-irradiation up to 10kGy were investigated. Blue value, water binding capacity and swelling power decreased, while alkali number ad solubility increased by γ-irradiation , which was more pronounced in glu-tinous corn starch than in non-glutinous corn starch. The optical transmittance increased with an increment of heating temperature and applied irradiation doses. No significant difference was observed in Hunter's color value between both starches isolated from non- irradiated and irradiated and irradiated corn grains. Amylograph viscosities decreased remarkably as dose levels increased. The overall effects of γ-irradiation was more distinguished in glutinous starch than in non-glutinous starch.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.222.2-223
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• 2003

추청벼와 삼강벼를 원료로 하여 전분을 제조하고 그 전분을 이용하여 초산 쌀 전분을 제조하여 얻어진 초산쌀 전분의 이화학적 성질을 검토하여 다음과 같은 결과를 얻었다. 초산 쌀 전분의 용해도와 팽윤력은 원료 전분에 비하여 높았으며 품종간에 약간의 차이를 나타내었다 광투과도는 원료 전분에 비하여 높았으며 원료 전력은 6$0^{\circ}C$, 초산 쌀 전분은 5$0^{\circ}C$부터 증가하기 시작하였으며, blue value는 원료 전분보다 낮게 나타났다. alkali number는 원료 전분보다 약7배 높았으며, 초산 쌀 전분 겔의경도, 응집성, 접착성, 점착성 및 저장성은 원료 전분 겔보다 높았으며 품종간에 약간의 차이를 나타내었다. Amylograph에 의한 초산 추정 및 삼강벼 전분의 호화개시온도는 각각 59$^{\circ}C$, 62$^{\circ}C$로서 초산 처리에 의해 5~6$^{\circ}C$ 낮아졌고, 초산 쌀 전분의 점도는 원료 전분에 비하여 14~38% 증가하였으며 추청벼 전분이 삼강벼 전분보다 높았다. 초산쌀 전분 입자의 표면구조는 원료 전분에 비하여 다소 팽윤되어 헝클어진 형태를 나타냈으며, 7$0^{\circ}C$ 30분 가열에 의해서 완전히 붕괴되었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.225-226
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• 2017

Recently, there has been a growing interest in the development of non-sintered binder to reduce CO2 emissions from the cement clinker manufacturing process and a number of studies have been conducted on fly ashes as an industrial by-product. However, in order to utilize fly ashes as a non-sintered binder, it is necessary to solve problems such as safety issues and economical efficiency due to use of an alkali activator. This study evaluates the material properties and compressive strength characteristics of three types of circulating fluidized bed boiler ashes. As a result, it was confirmed that the characteristics of each binder vary depending on the location of the power plant and the types of raw materials. In addition, it has been confirmed that the fluidized bed boiler ash shows a high compressive strength and can be used sufficiently as an non-sintered binder.

• Applied Biological Chemistry
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• v.28 no.4
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• pp.239-244
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• 1985

Physicochcmical properties of the Lotus root starch wert investigated. The shape of starch granules was elliptical with the average size of $20{\sim}35{\mu}$. Starch showed B-type X-ray pattern. The content of amylose was 22.1%. The blue value for starch and amylose were 0.280 and 0.692, respectively. The alkali number was 4.74. By X-ray diffraction examination, gelatinization began at $55^{\circ}C{\sim}60^{\circ}C$ and almost completed at $65^{\circ}C{\sim}70^{\circ}C$.