• Korean Journal of Materials Research
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• v.26 no.6
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• pp.320-324
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• 2016

Porous SiC beads were prepared by freeze-drying a polycarbosilane (PCS) emulsion. The water-in-oil (w/o) emulsion, which was composed of water, PCS dissolved p-xylene, and sodium xylenesulfonate (SXS) as an emulsifier, was frozen by dropping it onto a liquid $N_2$ bath; this process resulted in 1~2 mm sized beads. Beads were cured at $200^{\circ}C$ for 1 h in air and heat-treated at $800^{\circ}C$ and $1400^{\circ}C$ for 1 h in an Ar gas flow. Two types of pores, lamella-shaped and spherical pores, were observed. Lamellar-shaped pores were found to develop during the freezing of the xylene solvent. Water droplets in the w/o emulsion were changed into spherical pores under freeze-drying. At $1400^{\circ}C$ of heat-treatment, porous SiC was synthesized with a low level of impurities.

• Journal of the Korean Graphic Arts Communication Society
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• v.22 no.1
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• pp.83-94
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• 2004

PSR ink is used to insulation coating material that heat resistance is. The use purpose is used for bridge prevention, circuit protection, stabilization of insulation. Heat-cured resin was used mainly on the materials of PSR inks. But, UV-curing type resin in used. Also, because of recently environmental problem, ink is going to water type. Purpose of this study is to develop PSR ink that can develop in pure water. and experiment did that do from that find suitable oligomer and monomer and does brand ratio differ. Specially Knew that is extent water soluble UV resin develop possible is DPHA 10~50% that A/A1924 is 50~90wt %, monomer. As a result, when ratio of A/A1924 and DPHA low viscosity epoxy resin is 5:1.5:1.5, could get high sensibility pattern repeatability, tack and alkali-resistance.

• Journal of the Korean Society of Tobacco Science
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• v.17 no.2
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• pp.149-159
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• 1995

The freeze drying rate was investigated under various conditions such as pressure and moisture contents in order to establish the optimum condition for expansion of the culled flue cured tobacco lamina. The optimal pressure in the chamber to maintain the heat and mass transfer was about 0.8torr, When the moisture contents of sample was 50-60%, expanding rate was the optimum condition and the rate was 67-76%. As the thickness of the sample layers was increased, drying-rate was decreased conversely and this result seemed to be due to decline of heat and mass transfer coefficients. Differences with the position of its stalk were also observed in drying rate, and low stalk position leaves of 5 and 3 was the fastest. Key words : freeze drying, Popping, expansion tobacco.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.89-92
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• 2005

Our country has experienced variations in temperature as belong to the area of the continental climate that shows four significant seasons. These occur quality of construction. As the hydration of cement processes, the strength of concrete is developed. In order to improve the quality of concrete, various conditions including temperature and humidity should be maintained appropriately and concrete itself should be cured sufficiently This paper is basic experiment for estimating influence of strength by seasonal mock-up concrete's heat of hydration and estimate relationship of compressive strength development by curing temperature. And show basic document as quality control.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.289-292
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• 2004

This study was performed to know effective control of crack occurred by hydration heat, restraint of multiplication of hydration heat, through mechanical test, strength test and crack control test using fluosilicate salt based anti-crack agent made from by-product during phosphoric acid manufacturing process. Mix proportions for experiment were modulated at 0.495 of water to cement ratio and addition amount of fluosilicate salt based anti-crack agent to $1.0\%$. Condensation time was late and compressive strength of hardened concrete cured at several days was executed to evaluate characteristics of crack control for concrete. It is ascertained that characteristics of crack control for concrete could be improved by an adequate addition of fluosilicate salt based anti-crack agent.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.465-468
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• 2006

This paper investigates the effect of curing conditions on the strength improvement of polymer-modified mortars using epoxy resin with various curing methods. The polymer-modified mortars using epoxy resin are prepared with various polymer-cement ratios, and subjected to standard, hot water, heat cure and autoclave cures. The epoxy-modified mortars are tested for flexural and compressive strengths at desired curing methods. From the test results, the flexural and compressive strengths of the epoxy-modified mortars are hardly improved by the autoclave and hot water cures compared to the ideal cure of $20^{\circ}C$. Among the four types of curing methods, the strengths of the heat cured epoxy-modified mortars is largely improved. Especially, it is obtained in the mortars sealed with PVDC film.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.2
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• pp.216-227
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• 2007

Statement of problem: For the long-term success of removable partial dentures, the bonding between metal framework and denture base resin is one of the important factors. To improve bonding between those, macro-mechanical retentive form that is included metal framework design has been generally used. However it has been known that sealing at the interface between metal framework and denture base resin is very weak, because this method uses mechanical bonding. Purpose: Many studies has been made to find a simple method which induces chemical bond, now various bonding system is applied to clinic. In this experiment, shear bond strengths of heat-cured denture base resin to the surface-treated Co-Cr alloy were measured before and after thermocycling. Chemically treated groups with Alloy $Primer^{TM}$, Super-Bond $C&B^{TM}$, and tribochemically treated group with $Rocatec^{TM}$ system were compared to the beadtreated control group. The data were analyzed with two-way ANOVA. Result: 1. Shear bond strength of bead-treated group is highest, and Alloy $Primer^{TM}$ treated group, Super-Bond $C&B^{TM}$ treated group, RocatecTM system treated group were followed. Statistically significant differences were found in each treated group(p<0.05). 2. Surface treatment and thermocycling affected shear bond strength(p<0.05), however there was no interaction between two factors(p>0.05). 3. Shear bond strengths of bead-treated group and Alloy $Primer^{TM}$ treated group showed no statistically significant difference before and after thermocycling(p>0.05), and those of Super-Bond $C&B^{TM}$ treated group and $Rocatec^{TM}$ system treated group showed statistically significant difference after thermocycling(p<0.05).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3822-3826
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• 2012

We have studied the effect of temperature and exposure time on the UV curing rate of Urethane Acrylate. UV dose has been modulated by changing the electric power, and temperature has been controled by coating rate and water temperature of the coating roll. Curing rate was evaluated by measuring gel fraction of the cured film. It has been found that effect of coating velocity on the gel fraction of the final film is predominant, but role of temperature of the UV chamber is negligible. These observations imply that exposure time of UV light is critical to have a fully cured film. To better understand the effect of design and operating condition of UV coater on the behavior of UV curing of Urethane Acrylate, we have also conducted heat-flux analysis of UV chamber.

• Composites Research
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• v.16 no.6
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• pp.33-40
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• 2003

The initial thermal degradation of polymer matrix composite is not observed easily. At the beginning of thermal degradation of polymer matrix composites, phase transformation such as chain scission, oxidation occur, and then micro delamination is produced in matrix and interface between matrix and fiber before blistering. Initial heat damage deteriorate mechanical properties of composites. We presented the detection method of the initial heat damage of composites conveniently using ultrasonic technique. Absorption coefficient and material velocity was measured with thermal degradation and degree of cure. The more thermal degradation was progressed, the more absorption coefficient was increased. When the cure temperature is more high, the absorption coefficient of cured composite is increased and material velocity is decreased. We concluded that cure temperature is more high, the defects such as void is increased and molecular structure cured at high temperature has cross-linking structure which is more absorb the ultrasonic waves.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.4
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• pp.879-892
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• 2003

This thesis makes a review of symptoms and cause of the numbness in the literature. clinical case are studied and classified according to the Hyungsang of the patients. The followings are the conclusions: In case of Dam type persons, numbness is mainly caused by Fire with blood deficiency and so cured by tonifying the Jung and blood. In case of Bang Kwang type persons. it is generally caused by the deficiency of Ki and damp-phlegm and treated by reinforcing Ki and removing dampness. Persons of Jung and Hyal types are apt to be afflicted with numbness of deficiency symptoms which can be cured by tonifying the Jung and blood. Those of Ki and Shin types are inclined to get numb from the congestion and stagnancy and so treated by promotion the flow of Ki, dispelling stagnancy, resolving phlegm and promoting digestion. Numbness is common to the old people and women. The deficiency of blood and primordial energy is a cause of old people's numbness. Women get numb due to the pent-up feelings and emotional disturbance. The function disharmony of five Jang and six Bu makes the body lose the control of heat and cold or deficiency and excessiveness, which can be a cause of numbness. Especially the deficiency of the spleen results in numbness. When the special parts of the body become numb treatment must be decided after due consideration on which of the Jang and Bu or meridians is related to that affected area. In case of person with six meridian types. unbalance of Ki and blood leads the six atmospheric influences(wind, cold, heat, dampness, dryness and fire) get into the body through the most developed meridian and brings in numbness.