• KSBB Journal
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• v.11 no.4
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• pp.481-488
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• 1996

In spite of diverse applications of chitin derivatives, commercial use of chitin has been limited due to highly resistance to chemicals and the absense of proper solvents. One of methods to reduce such high resistance to chemicals is to make microcrystalline chitin(MCC) by hydrolysis of chitin. Presently, MCC is produced mainly by using high concentration of acid, but this treatment requires an extensive posttreatment to remove or recover acid. An alternative process for MCC production was developed by using dilute hydrochloric acid with ultrasound and hydrogen peroxide. The major parameters for this process were found to be acid concentration, swelling time and temperature, and irradiation time and frequency of ultrasound. The effects of these parameters on MCC molecular weight were investigated. The molecular weight of MCC produced at a typical condition was around 30,000 which was approximately 1/8 of that of chitin and approached to a constant value. This phenomenon was explained by introducing the model of molecular arrangement of cellulose. SEM analysis showed that both chitin and MCC had a fibrous shaped morphology and the fibril size of MCC was much smaller than that of chitin.

• Elastomers and Composites
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• v.34 no.4
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• pp.350-359
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• 1999

Conversion and oil-yield of a used automotive tire sample in supercritical decomposition and extraction for three solvents such as water, 28% ammoina solution and ammonia, were compared. Supercritical extraction with ammonia gave the highest conversion and oil-yield at the same temperature and pressure. In this paper, supercritical ammonia was used as major solvent and tetralin acting as hydrogen-donor, was used as cosolvent. As the amount of tetralin increased, oil-yield was Increased. When a tire sample was extracted by supercritical ammonia, oil-yield was 48.8% at $280^{\circ}C$, 22.3MPa. But when the weight ratio of tetralin to tire sample (weight of tetralin/weight of tire sample) was 5, oil-yield was 61.2% at $280^{\circ}C$ and 22.3 MPa. These phenomena indicate that as radicals produced in supercritical decomposition become stable, the polymerization and the second decomposition of products may be inhibited. Supercritical extraction of a tire sample swollen by tetralin gave high oil-yield although the amount of tetralin was a little.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.773-786
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• 2018

In this paper, viscosity features of sealant (bentonite-cement slurry), which is used for umbrella arch method in tunnel, were studied. The sealant must secure optimal strength and capacity for the waterproof and stabilization of borehole as well as to satisfy groutability. In this study, the variation of viscosity was measured with different mixing processes. With an increase of initial mixing period with water and bentonite mixture, the required time for the rapid increase of viscosity of the sealant is shorten. With increase of mixing period, the possibility of swelling of bentonite will increases and this can lead increase of the viscosity of the mixture. In addition, the behaviors of sealant vary with a drastic increase of the viscosity: thixotropy and rheopexy. Furthermore, the bentonite/water mixing period influences on the bleeding features of the sealant. Further study is required to introduce the guideline, which can be applicable in the field in the aspect of required capacity of the sealants and mixing processes of the ingredients.

• Korean Journal of Food Science and Technology
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• v.25 no.5
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• pp.461-467
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• 1993

The purpose of this study was to investigate the physico-chemical properties of potato starch heated with microwave. Two types of potato starches are prepared; in group A raw potato starch was heated with microwave and in group B potato starch was isolated from potato heated with microwave. Both groups were exposed to the microwave energy in a 560 W, 2,450 MHz oven for 60, 120, 180 and 300 seconds. As the microwave heating time took longer, free lipid decreased and bound lipid increased in both groups. The shape of starch granules, birefrigence and X-ray diffraction pattern were not changed much by microwave heating in both groups. Water binding capacity increased, but amylose content, swelling power and solubility decreased as the microwave heating time took longer. It was also found that the extent of decreases in swelling power and solubility were different between group A and group B.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.201-205
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• 1999

Hydroxypropylmethylcelluloses (HPMC) are cellulose ethers which may be used as the basis for hydrophilic matrices for controlled release oral delivery and offer the advantages of being non-toxic and relatively inexpensive. In this work, we designed new drug release system using HPMC as matrix, manufactured by direct compression technology and have investigated the effects of the controlling factors on drug release from a swellable hydrophillic delivery system. It was found that the release rate of the drug decreased with increasing the polymer molecular weight and the polymer content in tablets, and was independent of compaction pressure and pH of dissolution fluids. Especially, the ability of the anionic surfactant, sodium laurylsulfate, to retard the release of pseudoephedrine hydrochloride from HPMC was characterised. With increasing the concentration of the sodium laurylsulfate within the matrix, drug release rate decreased. It is believed that, provided the pseudoephedrine hydrochloride and the sodium laurylsulfate are oppositely charged, they will bind together in situ within the HPMC matrix, leading to reduced drug release rates.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.514-520
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• 1996

The purpose of this study was to develop the production technology of modified starch. Corn starches were gamma irradiated at 0-110 kGy and the effect of irradiation dose levels on the physicochemical properties of corn starches were investigated. Blue value linearly decreased, while alkali number and solubility markedly increased as irradiation dose levels were increased. The optical transmittance increased as applied irradiation dose levels were increased in the temperature range of $65-95^{\circ}C.$ Water binding capacity and swelling power showed maximum value at 30 and 10 kGy, respectively and they tended to decrease thereafter. Gelatinization viscosity of the gamma irradiated starch considerably decreased as compared to that of the non-irradiated starch. Irradiation at 110kGy resulted in a marked reduction of peak viscosity and cooling viscosity at $30^{\circ}C$ by 100 and 300 times, respectively. The physicochemical properties of corn starch irradiated at 30 kGy were similar to those of commercial acid-modified starch, while those of corn starch irradiated at 100 kGy were similar to those if oxidized starch.

• Korean Journal of Food Science and Technology
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• v.8 no.4
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• pp.207-211
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• 1976

Treated with various methods, body muscle of squid was cross section, stained by Van Gieson staining method, and observed microscopically to study on the state of thin layer of skin separated from meat. Results obtained were summarized as follows : 1. By general hot spring treatment were 1st. 2nd. and 3rd. layers of skin removed from squid muscle but 4th. not. 2. By boiling treatment was tissue of muscle fibre fissured largely toward the muscle fibre. 3. Sodium acetate treatment was superior to sodium nitrate, sodium sulfate and sodium tartrate treatment in the effect that the skin was separated from meat. Especially, concentrate solution of sodium acetate had the most excellent effect in the chemical reagent treatment. 4. By proteolytic enzyme treatment were 1st. 2nd. 3rd. and 4th. layers of skin removed all from squid muscle and the boundary fibre between skin and meat swelled in particular. 5. Two kinds of skin removing method, proteolytic enzyme treatment and sodium acetate treatment, were desirable to the actual processing.

• Tunnel and Underground Space
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• v.21 no.1
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• pp.20-32
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• 2011

Failure aspects of cut-slope, which induce the sequential collapses during the excavation stage, have been analyzed. Slope rock structures are investigated by examining the orientations and positions of discontinuity planes calculated based on the BIPS image inside the boreholes. Drilled core log has been also used to identify the structural defects. Clay minerals of swelling potentials are detected through XRD analysis. Numerical analysis for slope stability has been performed by utilizing the joint shear strength acquired from the direct joint shear test. Cut-slope collapse characteristics have been studied by investigating the posture of failure-prawn joint planes and the stability of tetrahedral blocks of different sizes. Cross-section analysis has been also performed to analyze the cut-slope behavior and to estimate the amount of reinforcement required to secure the stability of cut-slope. Behavior of reinforced cut-slope is also investigated by analyzing the slope monitoring data.

• Food Science and Preservation
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• v.17 no.5
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• pp.667-673
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• 2010

Effects of substituting wheat flour with rice flour on bread-making properties were investigated. Rice(Oryza sativa L.) cultivars were 'Goami2(G2)', a functional rice containing higher non-digestible carbohydrates, and 'Chucheongbyeo (CC)', an ordinary Japonica rice. Rice flour was substituted at 10, 20 and 30% in wheat bread formulation, and the composite flour was used for yeast-leavened bread making. Peak and final viscosity of G2 rice flour was significantly lower than that of CC rice flour. Mixograph analysis indicated that replacement of G2 rice flour increased dough water absorption and mixing time compared to wheat flour. But, typical mixograph pattern was not found in the dough from composite flour with CC rice flour. As increasing the amount of rice flour, the G2 rice breads showed a significant decrease in loaf volume, but an increase in bread crumb firmness(g). For the CC rice breads, no significant difference(p<0.05) was observed in loaf volume and crumb firmness, ranging 1012~1050 cc and 433~482g, respectively. The results revealed that Chucheongbyeo is more suitable for bread-making with the composite flour of rice(10~30%) and wheat flour.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.63-70
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• 2005

The purpose of this study was to investigate how to modify the physical properties of cellulose after thermal treatment. Cellulose was treated between $225^{\circ}C$ and $325^{\circ}C$ for 3 hrs under air flow, and then the thermally treated cellulose was measured to specific surface area, constitute elements, consumption ofacid and base, as well as the adsorption capacity of ethylamine vapor. The higher was the treating temperature from $225^{\circ}C$ to $325^{\circ}C$, the lower was the total yield of cellulose. Elemental analysis revealed that carbon content in thermally treated cellulose was gradually increased in proportion to temperature increment. The amount of acidic functional groups tended to increase up to $300^{\circ}C$, after then to be lowered slightly. In principle, no alkaline functional groups were found in thermally treated cellulose. In case of treatment with $325^{\circ}C$, only a few amount of alkaline functional groups were detectable. Specific surface area of thermally treated cellulose are determined to $1.9m^2/g$, which value can become higher when the treated temperature rises. The thermally treated cellulose at $275^{\circ}C$ shows the highest adsorption capacity of ethylamine at $40^{\circ}C$ for 4 hrs. Solubility of those two celluloses with WPG (Weight Percent Gain) value of 113% and 108%, respectively, was determined to almost 100%. X-ray diffractogram of thermally treated cellulose suggested that the crystalline structure of cellulose began to be destroyed at the temperature of $275^{\circ}C$. As a conclusion, changes of such a physical properties make it possible to weaken inter and/or intra hydrogen bond in crystal region of cellulose macromolecules. When thermally treated cellulose adsorbs ethylamine, it turns to be well soluble to water.