• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.556-560
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• 2010

An atmospheric surface modification using plasma treatment method was applied to butadiene rubber to improve its adhesion strength by plate type reactor. In order to investigate the optimum reaction condition of plasma treatment, type of reaction gas(nitrogen, argon, oxygen, air), gas flow rate(30~100 mL/min), treated time(0~30 s) and primer modification method(GMA, 2-HEMA) were examined in a plate type plasma reactor. The results of the surface modification with respect to the treatment procedure was characterized by using SEM and ATR-FTIR. As the gas flow rate and treated time increases the contact angle decreases. The greatest adhesion strength was achieved at optimum condition such as flow rate of 60 mL/min, treated time 5 s and modification primer containing 2-HEMA for air. Due to the atmospheric surface modification using plate plasma method consequently reduced the wettability of butadiene rubber and resulted in the improvement of the adhesion.

• Archives of Craniofacial Surgery
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• v.9 no.2
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• pp.45-50
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• 2008

Purpose: Traditionally, titanium miniplate has been used for rigid fixation of mandible fractures. However, the limitations of metal plate have been reported such as hypersensitivity, interference with the cranio-facial growth of growing child, secondary bone resorption around the plate, foreign body reaction, declination of primary callus formation, and bone atrophy, and so forth. Recently, biodegradable miniplate has been introduced and used as an alternative to the metal plate despite of its lower strength. This study evaluated the usefulness and stability of biodegradable plate and screw for treatment of mandible fractures. Methods: In this study, 61 patients(92 areas) diagnosed as mandible fracture in the last 2 years have been reviewed. We used titanium plate and screw in 32 patients, and biodegradable plate and screw($INION^{(R)}$) in 29 patients. Stability of plates and screws, bony healing process and its side effects were observed by clinical and radiographic assessment. Results: In the titanium material group, one of malocclusion, two of mouth opening limitation, three of pain, three of palpation were shown. The plate of six patients involved in these complications were removed. In the biodegradable group, two of mouth opening limitation, two of pain, one of localized wound infection were shown and one plate was removed secondarily. Conclusion: There was no statistical difference between two groups in bony healing and complication rates. Biodegradable implants show efficient stability during initial bone healing and low side effects in long-term follow up periods.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.114-119
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• 1999

When NaOCl was generated and put into sea-water cooling machine in order to overcome the biological hindrances against sea-water cooling machine, it was converted into metallic ion, particularly Ca and Mg, as a hydrate in sea-water and is to stick to electrolyte as a side reaction. This phenomena make the distance between the electrolytes narrow to decrease the flow rate, which induces the local vortex flow which erodes the pole plate. Moreover, this increases the resistance of the electrolyte as well as voltage to decrease the electrolytic efficiency, which has curtailed a chlorine yield and caused a pole plate cut. We are able to overcome these problems by chemical cleaning and intend to extend the life-time of electrolyte and to increase output of the sea-water electrolysis facilities by studying optimal policy regarding chemical cleaning of electrolytic cell. Cleaning time of electrolytic facilities is determined when both increase in electrolytic efficiency and decrease in pole-plate voltage are 10%. At this time as operating current of electrolytic facilities is high, operating time is diminished. Whereas, parameter of end point determination according to cleaning is Mg ionic concentration in solution. When we use Cleaner as a 7wt% HCl, cleaning time is about 80min proper. We are able to maintain pole plate performance by protecting against pole plate cut by means of electrolytic by-product, improve operating rate of facilities, and cut down on maintenance expenditure after acidic cleaning.

• Polymer(Korea)
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• v.25 no.4
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• pp.594-601
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• 2001

Direct thermal lamination of polyethylene film on aluminum plate without using adhesive was tried by modifying their surfaces to have polar groups. Polyethylene film was modified by treating with oxygen or acrylic acid plasma. Aluminum plate was modified by treating with boiling water or diaminocyclohexane plasma. Fairly high adhesion strength was obtained even in the case when only the polyethylene film was modified, and adhesion strength was so high that film was broken during the adhesion test if both the film and the aluminum plate were modified. Even chemical bonding seemed to be possible when the film treated with acrylic acid was laminated on the plate treated with diaminocyclohexane plasma by forming amide linkage through the reaction between COOH groups on the film surface and NH$_2$ groups on the plate surface.

• Journal of the Korean Society of Combustion
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• v.10 no.3
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• pp.17-24
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• 2005

A sub-millimeter scale catalytic combustor with a simple plate-shaped combustion chamber was fabricated. A porous ceramics support coated with platinum catalyst was placed in the chamber. The combustor has a gallium arsenide window on the top that is transparent to infrared ray. The temperature distribution in the combustion chamber was measured using infrared thermal imager while hydrogen-air premixture is steadily supplied to the combustor. The area where the catalytic reaction took place broaden for higher flow rate and lower equivalence ratio made activated area in the combustion chamber broaden. The amount of coated platinum catalyst did not affect the reaction. Stop of reaction, which is similar to flame quenching of conventional combustion, was investigated. Large content of heat generation and broad activated area are essential criteria to prevent stop of reaction that has a bad effect on the combustor performance.

• Journal of the Korean Applied Science and Technology
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• v.11 no.1
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• pp.53-60
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• 1994

The Synthesis of azobenzene containing long chain fatty acid and poly vinyl alcohol by esterification reaction($C_{n}-Azo-PVA$) was optimized, starting from P-(P'-hydroxy phenyl azo)-benzoic acid and the product of reaction containing azobenzene chromophores was investigated by ultraviolet spectrophotometery in toluene solvent at room temperature. In addition, UV absorption spectra of Langmmuir Blodggett (LB) film deposited on quartz plate have been measured and the structure of these compounds were ascertained by means of Ultraviolet and FT-IR. Recrystallization of reaction product in the solvent results the experimental yield obtained about 22.27% P-(P'-octadecyloxy phenyl azo)-benzoic acid-poly vinyl alcohol. Long chain azobenzene derivative-poly vinyl alcohols are induced phtoisomerization by u, v, and visible light irradiation. The LB film of azobenzene containing long chain fatty acids($C_{18}-Azo-PVA$) are possible of being applied to functional molecular devices such as photomemory and light switching.

• Journal of International Academy of Physical Therapy Research
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• v.2 no.1
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• pp.222-228
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• 2011

With comparison of maximum vertical reaction force and lower limb on drop landing between normal and flat foot group, this study is to provide fundamental data of the prevention of injury and the treatment of exercise which are frequently occurred on flat foot group's drop landing. The surface electrodes were sticked on lateral gastrocnemius muscle, medial gastrocnemius muscle, tibialis anterior and the drop landing on a force plate of 40cm was performed with a normal group who had no musculoskeletal disease and a flat foot group of 9 people who had feet examinations. Vertical reaction force were significantly statistically different between two groups(p<.001). Muscle activity of lower limbs in all three parts were not statistically different but showed high tendency on average in the flat foot group. The flat foot group had difficulties in diversification of impact burden and high muscle activity. Therefore, it was suggested that muscular strengthening of knee joints and plantar flexions of foot joints which were highly affected in impact absorption will be required.

• Journal of the Korean Ceramic Society
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• v.30 no.1
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• pp.41-45
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• 1993

synthesis of artificial kaolinite and the transformation of domestic halloysite have been attempted by means of the hydrothermal treatment. The hydrothermal reaction of the mixtures of gibbsite and amorphous silica was conducted for the synthesis of kaolinite under the pressure of 125MPa at 30$0^{\circ}C$ and especially the seed of kaolinite was added so as to facilitate the synthesis reaction. Domestic pink kaolin of B-grade was hydrothermally treated, in a similar way, for the transformation of crystalline form of it. Boehmite and the artificial kaolinite less than 0.4${\mu}{\textrm}{m}$ could be obtained through the hydrothermal reaction. It could also be found that the majority of hyalloysite was transformed into the plate-type kaolinite through the recrystallization by treating hydrothermally for a long time.

• Journal of applied mathematics & informatics
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• v.41 no.5
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• pp.1085-1102
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• 2023

In this study the magneto hydrodynamic (MHD) micro polar fluid flow of a viscous incompressible fluid past a porous medium in the presence of chemical reaction is considered. This work is devoted to investigate the Soret effect and Electromagnetic radiation effect and analyze analytically. In the energy equation the applied magnetic field strength and in the concentration equation the Soret effect are incorporated. The basic PDE (partial differential equations) are reduced to ODE (ordinary differential equations) using non dimensional variables. Then the analytical solution of the dimensionless equations are found using perturbation technique. The features of the fluid flow parameters are analyzed, discussed and explained graphically. The graphical solutions are found using MATLAB R2019b. Skin friction coefficient at the wall, Couple stress coefficient at the plate and the local surface heat flux are also thoroughly examined. Overall, this study sheds light on the complex interplay between physical parameters in the behavior of MHD micro-polar fluid past a porous medium in the presence of chemical reaction.

• Structural Engineering and Mechanics
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• v.63 no.3
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• pp.347-359
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• 2017

Blast resistant gates are required to be lightweight and able to mitigate extreme loading effect. This may be achieved through innovative design of a gate and its supporting frame. The first is well covered in literature while the latter is often overlooked. The design of supporting frame depends mainly on the boundary conditions and corresponding reaction forces. The later states the novelty and the aim of this paper, namely, the analysis of reaction forces in supporting structure of rectangular steel gates subjected to "far-field explosions". Flat steel plate was used as simplified gate structure, since the focus was on reaction forces rather than behaviour of gate itself. The analyses include both static and dynamic cases using analytical and numerical methods to emphasize the difference between both approaches, and provide some practical hints for engineers. The comprehensive study of reaction forces presented here, cover four different boundary conditions and three length to width ratios. Moreover, the effect of explosive charge and stand-off distance on reaction forces was also covered. The analyses presented can be used for a future design of a possible "blast absorbing supporting frame" which will increase the absorbing properties of the gate. This in return, may lead to lighter and more operational blast resistant gates.