• Applied Microscopy
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• v.31 no.4
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• pp.385-392
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• 2001

The purpose of this study was to evaluate the histological toxicity of chitosanoligosaccharide on the rat. A healthy male of Wistar rat that weighted $250{\pm}350g$ was used for experiment The experimental group was divided into five groups. Group 1 was control group which treated with general food Group 2 was $F_1$ generation which was born by mating of 0.1% (1 mg/ml) chitosanoligosaccharide was supplied by feeding ad libitum for 30 days. Group 3 was $F_2$ generation which was born by mating $F_1$ generation. Group 4 was treated with 90 days of 0.1% (1 mg/ml) chitosan oligosaccharide. Group 5 was treated with 365 days of 0.1% (1 mg/ml) chitosanoligo saccharide. All experimental groups were used to 10 rat. The results were as follow: The RER dilation was observed Group 4. However, there were no significantly changes of ultrastructures in the other groups compared to the control. It was concluded that chitosanoligosaccharide can be used for nontoxic natural material.

• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.153-158
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• 2002

$Al_2O_3$ composites powders with 1∼11 wt% $TiO_2$ were prepared by wet method and sintered at 1350$^{\circ}C$, 1450$^{\circ}C$ for 2h. Mechanical properties and microstructural evolution were investigated in this study. $Al_2O_3$-3 wt% $TiO_2$ composite were high bulk density of 2.37 g/$cm^3$ and low apparent porosity of 6.3%. The composites containing of 3 wt% $TiO_2$ showed moderately high bending strength of 68.9 MPa and the young's modulus of 35.5 MPa. The composites with increasing $TiO_2$ contents exhibit reduced thermal expansion coefficient due to the formation of $Al_2TiO_5$ phase.

• Journal of the Korean Geotechnical Society
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• v.27 no.9
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• pp.47-53
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• 2011

Marine dredged soils taken from navigation channels or construction sites of coastal area usually have a lot of salt in pores of clayey soils. This paper investigates effect of salt on mechanical characteristics of non-salt and salt-rich stabilized dredged soil. The stabilized dredged soil (SDS) consisted of dredged soil and cement. Several pairs of SDS with non-salt and salt-rich dredged soils, noted as N-SDS and S-SDS, respectively, were prepared to compare their strengths and compressibility characteristics. The microstructures, strength and compressibility characteristics of N-SDS and S-SDS specimens at 7 and 28 days of curing time were evaluated using scanning electronic microscope (SEM), unconfined compression test, and oedometer test. It was found that salt concentration of clayey soil affected not only the formation of soil structure but also the strength development of mixture. The compression index and swelling index of S-SDS were also greater than those of N-SDS, which indicated that the compressibility of mixture increased due to salt concentration. Salinity in clayey soil had a negative effect on the strength development and compressibility characteristics of stabilized dredged soils.

• Composites Research
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• v.23 no.2
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• pp.31-39
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• 2010

In this paper, composite panels with hat-shaped stiffeners were made using the co-curing, co-bonding and secondary bonding methods. Co-curing is a manufacturing method in which the hat part and the plate are cured simultaneously in a manner that is more cost effective than other methods. Co-bonding is a method in which the stacked prepregs are cured with other cured parts, and secondary bonding is a method in which cured parts are bonded together using an adhesive. A rubber mold was manufactured for co-curing of composite panel with hat-shaped stiffeners, and finite element analyses were done to evaluate the expanding pressure of the rubber mold consistent with the curing temperature. The manufactured panels were also evaluated using a 3-D measurement tester and an ultrasonic tester. Pull-off tests were performed to evaluate their mechanical properties.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.427-435
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• 2012

In order to evaluate the effects of exposure conditions on the resistance to sulfate attack of normal and blended cement mortars, several mechanical characteristics of the mortars such as expansion, strength and bulk density were regularly monitored for 52 cycles under sodium sulfate attack. The mortar specimens were exposed to 3 different types of exposure conditions; 1) continuous full immersion(Exposure A), continuous half-immersion(Exposure B) and cyclic wetting-drying(Exposure C). Experimental results indicated that the maximum deterioration was noted in OPC mortar specimens subjected to Exposure B, showing the wide cracks in the portions where attacking solution is adjacent to air. Additionally, the beneficial effect of ground granulated blast-furnace slag and silica fume was clearly observed showing a superior resistance against sodium sulfate attack, because of its lower permeability and densified structure. Thus, it is suggested that when concrete made with normal cement is exposed to sulfate environment, proper considerations on the exposure conditions should be taken.

• Korean journal of food and cookery science
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• v.8 no.1
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• pp.9-14
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• 1992

The morphological properties of acorn starch granules and starch gels were examined with scanning electron microscope and X-ray diffractometer. The shape of acorn starch granule was rounded triangular and some elliptical. The size distribution of starch granule was also analyzed. The mean value of minor axis, major axis and the ratio of those were 4.785 $\mu\textrm{m}$, 7.30 $\mu\textrm{m}$ and 0.68, respectively. The surface micro-structure of acorn starch gels were investigated by SEM. Acorn crude and refined starch gel were very different in surface micro-structure. X-ray diffraction pattern of acorn starch was C-type, and the pattern of acorn starch gels were extremely different because of disintegration of starch granules by gelatinization. The diffraction intensity of acorn refined starch gel was slightly higher than crude starch gel.

• Korean Journal of Ichthyology
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• v.18 no.2
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• pp.87-96
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• 2006

Reproduction and organ system of the oily bitterling, Acheilognathus koreensis in Isa stream were investigated by means of histological methods. Sex ratio was observed 1 : 1 in female to male. The gonadosomatic index (GSI) of the female showed two peak in December and April. The ovipositor length index (OLI) represented irregular change. From the histological analysis of the organ system, epidermal atrophy and hyperplasia of pigment cell were observed in the skin. Epithelial layer lifting of the lamella and bifurcation of the filament were observed in the gill. Also histological changes as congestion, cytoplasmic degeneration of hepatic cell, glomerular dilatation, hyaline droplet degeneration of renal tubule epithelium and pycnosis of interstitial cell were identified in the liver and kidney, respectively.

• Applied Microscopy
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• v.24 no.4
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• pp.1-12
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• 1994

Various plastids in leaf and bracteal tissues of Cannabis sativa L. were examined by electron microscopy. Young chloroplasts without starch grain in mesophyll cells were ellipsoidal, and osmiophilic globules within them were common in stroma. During the plastid differentiation, the mature chloroplasts in mesophyll were changed in shape depending on the numbers and sizes of starch grain in stroma. Electron-dense granular substances were occurred along the outer membrane of chloroplasts in mesophyll. Typical plastids with reticulate body were present in the glandular trichomes. Electron-grey material appeared along the surface of a plastid. A light area in reticulate body is considered to represent junction point of thylakoids.

• Korean journal of food and cookery science
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• v.20 no.4
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• pp.396-402
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• 2004

The aim of this study was to examine the effect of rice protein on the network structure of the Jeung-Pyun. The major component of Jeung-Pyun rice protein was extracted, the change of rice protein during the Jeung-Pyun fermentation was assessed, and the effect on the viscosity and volume of adding protease to Jeung-Pyun was investigated. In addition, the result of adding protein to rice starch on the viscosity and volume of Jeung-Pyun was that the rice protein mediated the volume and expansion ability. The results were as follows. In rice and dough of Jeung-Pyun, the SDS soluble protein content was higher than that of wheat flour and no change was detected in the amount of extracted protein with the fermentation time. However, in the FPLC pattern, low molecular weight peaks were decreased with the fermentation time, which indicates the increase in the ratio of high molecular weight substances. In contrast, the addition of protease substantially decreased, the viscosity and volume of Jeung-Pyun, whereas the viscosity and volume were increased by adding protein to rice starch in order to reconstitute Jeung-Pyun. This suggested that rice protein in Jeung-Pyun had a mediating effect on both the volume and the formation of the texture.

• Journal of the Korean GEO-environmental Society
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• v.11 no.10
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• pp.15-24
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• 2010

In the case of underground power utilities pipe such as circular pipe, the most difficult problem is low compaction efficiency of the bottom of pipe inducing the failure of utilities. To overcome this problem, various studies have been performed and one of these is CLSM(Controlled Low Strength Materials) accelerated flow ability. But underground power utilities pipe backfill materials is also needed to have good thermal property that can dissipate the heat as rapidly as it is generated. So, in this study, we performed thermal resistancy test for various materials such as sand, weathered soil, clay and mixed soil to analyze the thermal characteristics of CLSM(Controlled Low Strength Materials) with accelerated flow ability for various conditions(water content, unit weight, void ratio, curing time) and to evaluate the applicability for backfill material of underground power utilities pipe. The test results of 16 specimens for thermal resistancy test showed good thermal property that maintained below $85^{\circ}C\;cm/W$.