• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.319-323
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• 1999

Asymmetric polyetherimide membranes were prepared by phase inversion method. In the modification of the skin layers of polyetherimide membranes, the effects of NaOH concentration on the morphology and pervaporation separation of water-isopropanol mixtures were investigated. With increasing concentration of NaOH solution, polyamicacid structure was formed by the hydrolysis of imide group of polyetherimide, and the thickness of dense layer of the asymmetric membrane increased. In the pervaporation separation of water-isopropanol mixtures the overall permeation rate decreased and the separation factor increased with increasing concentration of NaOH solution. However, when the concentration of NaOH solution was very high, the permeation rate increased but separation factor decreased. From these results, it was found that the permeation behaviors of asymmetric polyetherimide membranes depended upon the concentration of NaOH solution. These modified membranes showed that both the permeation rate and separation factor increased as the operating temperature increased.

• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.249-262
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• 1997

The present study investigates the effects of calcium sulfate graft on the periodontal healing in intrabony periodontal defects of dogs. Following the general anesthesia with 30mg/kg pentobarbital injected intravenously, the first premolar was extracted and full-thickness periodontal flap was elevated from the second premolar to the fourth premolar. The portion of premolars coronal to the alveolar crest was removed and mesial and distal roots were separated. Exposed root canals were sealed with Caviton and covered completely with flaps sutured. Following the healing period of 12 weeks, the surgical sited were uncovered and $4{\times}4mm$ intrabony defects were surgically created. Those defects with calcium sulfate graft following the root planing was designated as the test sites and those with flap surgery-only were designated as control sites. The animals were sacrificed after 8 weeks and the healing was histologically analyzed. The results were as follows. 1. No foreign body reaction or inflammation were observed in either groups. Calcium sulfate was completely resorbed in the test sites. 2. New cementum was observed coronal to the notch in both groups. Connective tissue fibers were oriented parallel to the root surface in the controls. Connective tissues were formed in large amount in the sites. 3. Test sites showed marked amount of new bone formation while the control sites showed minimal bone gain. 4. Root resorption was observed in coronal portions of th control Sites. The results suggest that calcium sulfate is a biocompatible graft material with a potential for new bone and cementum formation.

• Journal of the Korean Chemical Society
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• v.46 no.5
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• pp.407-411
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• 2002

A method to determine lead ion in aqueous media using an optical sensor loaded on a fluorescent optode membrane incoporating a metal ion-selective ionophore, a proton-selective chromoionophore and lipophilic anionic sites has been studied. The effects of pH and thickness of membrane on the fluorescence intensity were investigated. The effects of foreign ions such as $Na^+$, $K^+$, $Mn^{2+}$ and $Zn^{2+}$ on the determination of lead ion were also studied. The linear range in the calibration curve for the determination of lead ion was found to be 5.0${\times}10^-7$ to 5.0${\times}$$10^-3$M and the correlation coefficient in this range was -0.99107 under the optimal experimental conditions. The relative standard deviation of the blank signals was 3.0% and the detection limit of lead ion was 5.0${\times}$$10^-9$M.

• Journal of the Korean Ceramic Society
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• v.50 no.4
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• pp.301-307
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• 2013

SiC hollow fiber was fabricated by curing, dissolution and sintering of Al-PCS fiber, which was melt spun the polyaluminocarbosilane. Al-PCS fiber was thermally oxidized and dissolved in toluene to remove the unoxidized area, the core of the cured fiber. The wall thickness ($t_{wall}$) of Al-PCS fiber was monotonically increased with an increasing oxidation curing time. The Al-PCS hollow fiber was heat-treated at the temperature between 1200 and $2000^{\circ}C$ to make a SiC hollow fibers having porous structure on the fiber wall. The pore size of the fiber wall was increased with the sintering temperature due to the decomposition of the amorphous $SiC_xO_y$ matrix and the growth of ${\beta}$-SiC in the matrix. At $1400^{\circ}C$, a nano porous wall with a high specific surface area was obtained. However, nano pores grew with the grain growth after the thermal decomposition of the amorphous matrix. This type of SiC hollow fibers are expected to be used as a substrate for a gas separation membrane.

• Membrane Journal
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• v.9 no.4
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• pp.230-239
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• 1999

Perchlorate ion-selective electrodes in PVC membranes that respond linearly to concentration 106 M were developed by incorporating the quaternary phosphonium salts as a canier. The effects of the chemical structure, the contents of canier, the kind of plasticizer and the membrane thickness on electrode characteristics such as the electrode slope, the linear respone range and the detection limit were studied. With this results, the detectable pH range, selectivity coefficients and AC impedance characteristics were compared and investigated. The perchlorate ion substituents of the quaternary phosphonium salts like tetraoctylphosphonium perchlorate (TOPP) , tetraphenylphosphonium perchlorate(TPPP), and tetrabutylphosphonium perchlorate(TBPP) as a canier were used. The electrode characteristics were better in the ascending order of TBPP < TPPP < TOPP, with the increase of carbon chain length of the alkyl group. Dioctylsebacate(OOS) was best as a plasticizer, the canier contents were better with 11.76 wt% and the optimum membrane thickness was 0.19 mm. Under the above condition, the electrode slope was 56.58 mV/$^P{ClO}_4$,the linear response range was $10^{-1}$\times$10^{-6}$ M, the detection limit was 9.66 x $10^{-7}$ M. The performance of electrode was better than Orion electrode. The electrode potential was stable within the pH range from 3 to 11. The order of the selectivity coefficients for the perchlorate ion was sol < F < Br < 1. With the result of impedance spectrum, it was found that the equivalent circuit for the electrode could be expressed by a series combination of solution resistance, parallel circuit consisting of the double layer capacitance and bulk resistance and Warburg impedance. And solution resistance was almost not appeared and Warburg impedance was highly appeared by diffusion. Then Warburg coefficient was 1.32$\times$$10^74 $\Omega$ $\cdot$ ${cm}^2/s^{1/2}$.

• The Journal of Korean Medicine
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• v.20 no.2
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• pp.146-156
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• 1999

The present study was performed to investigate the effect of Yangkyuksanhoa-tang on the morphological changes of the basilar artery after experimentally induced subarachnoid hemonrrhages(SAH). Yangkyuksanhoa-tang has been used freguently for cerebrovascular accident Sprague Dawley rats weighing between 350-400 g were used. The 6 normal rats and 24 SAH elicited rats were used, The SAH induced by injection of the fresh autologus heart blood (0.3-0.4 ml) into the cisterna magna through the posterior atlanta-occipital membrane, Sample group was given 3.3 ml/kg/day of Yangkyuksanhoa-tang extracts for 2 days after SAH. The experimental animals were killed at 48hrs after SAH. The morphological changes of the arterial walls were examined by light and electron microscopy. Following are the obtained results: 1. In SAH elicited rats, the size of the lumen in basilar artery was diminished by about 45% and the thickness of arterial wall was increased by about 82%. In SAH elicited rats with Yangkyuksanhoa-tang treatment, the size of the lumen in basilar artery was merely diminished by about 18% and the thickness of arterial wall was merely increased by about 19%. 2. In light microscopic examination, the endothelium was swollen into a cuboid shape and the layer of smooth muscle was increased in the basilar artery of SAH elicited rats. In SAH elicited rats with Yangkyuksanhoa-tang treatment, the size of the lumen in basilar artery was enlarged and the thickness was decreased than in SAH elicited rats. The endothelium was flattened into a squamous shape and the layer of smooth muscle was decreased more than in SAH elicited rats. 3. In electron microscopic examination, the endothelial cells with fragmentation nuclei were changed into a cuboid shape and the internal elastic lamina were folded at the basilar artery of SAH elicited rat. The nuclei of smooth muscle cells were changed into a round or crumpled shape. The length of smooth muscle was shorten and thickness was increased. But all kinds of morphologic changes were diminished in SAH elicited rats with Yangkyuksanhoa-tang treatment. Conclusion : Yangkyuksanhoa-tang extracts were effective to treat cerebral vasospasm after experimentally induced subarachnoid hemorrhage in rats.

• Korean Journal of Veterinary Research
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• v.46 no.4
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• pp.305-313
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• 2006

The primary goal of the wound healing is rapid wound closure. Recent advances in cellular and molecular biology have greatly expanded our understanding of the biologic processes involved in wound repair and tissue regeneration. This study was conducted to develop a new sponge type of biomaterial to be used for either wound dressing or scaffold for tissue engineering. We designed to make a comparative study of the wound healing effect of silk fibroin/hyaluronic acid (SF/HA) blend sponge in full-thickness dermal injury model of rat. Two full-thickness excisions were made on the back of the experimental animals. The excised wound was covered with either the silk fibroin (SF), hyaluronic acid (HA) or SF/HA (7 : 3 or 5 : 5 ratio) blend sponge. On the postoperative days of 3, 7, 10 and 14, the wound area was calculated by image analysis software. Simultaneously, the tissues were stained with Hematoxylin-Eosin and Masson's trichrome methods to measure the area of regenerated epithelium and collagen deposition. In addition, we evaluated the degree of the epithelial cell proliferation using immunohistochemistry for proliferating cell nuclear antigen (PCNA). We found that the half healing time ($HT_{50}$) of SF/HA blend sponge treated groups were significantly decreased as compared with either those of SF or HA treatment group. Furthermore, SF/HA blend sponges significantly increased the size of epithelialization and collagen deposition as well as the number of PCNA positive cells on epidermal basement membrane as compared with those of control treatment. Especially, the 5 : 5 ratio group of SF/HA among all treatment groups was most effective on wound healing rate and histological studies. These results suggest that SF/HA blend sponges could accelerate the wound healing process through the increase of epithelialization, collagen deposition and basal cell proliferation in full thickness skin injury.

• Archives of Plastic Surgery
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• v.35 no.4
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• pp.373-378
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• 2008

Purpose: In full thickness burn, the depth of burn is known to increase until around 1-3 days after the burn. However, no study on how the depth increase during the first 24 hours has been conducted. Therefore, the authors investigated how the depth of burn changes within the first 24 hours after the burn by using the standardized burn model. Methods: A total of four experiments on pigs were carried out for this study. Experiment 1 was performed to examine how temperature affects the depth of burn. The digitally controlled aluminum thermal block was set at different temperatures-80, 90 and 100 degrees in Celsius, respectively. Then the pig was exposed to the block for 15 seconds each time. The time exposed to heat was set as a variable for the Experiment 2. The temperature was maintained at 80 degrees Celsius, and the pig was contacted with the thermal block for 5, 10 and 20 seconds, respectively. The biopsy of the tissues were performed in one hour, 6 hours, 24 hours, and 7 days after the burn. After hematoxylin and eosin staining a percentage of the depth from a basement membrane of epidermis to the deepest tissue damaged by the burn against total dermal thickness was measured. Results: In Experiment 1, the depth of burn increased considerably as time passed by. At all three temperatures, differences in depths measured in 6 and 24 hours, and in 1 hour and 7 days were both significant. In addition, the depth deepened as the temperature went higher. In the case of Experiment 2, the depth of burn also increased significantly as time passed by. At all three times, differences in depth measured in 6 and 24 hours, and in 1 hour and 7 days were also significant. Moreover, the depth extended with longer contact time when it was compared according to the time. Conclusion: Full thickness burn progressed rapidly from 6 to 24 hours after the burn and the depth of burn was almost decided within the first 24 hours after the burn. On the other hand, partial thickness burn also advanced from 6 to 24 hours after the burn but the depth deepened at slower level.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.6
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• pp.394-398
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• 2014

We fabricated the electrolyte-dielectric-metal (EDM) sensor on the base of AAO (anodic aluminum oxide) template with variation of the anodizing temperature. When a surface is immersed or created in an aqueous solution, a discontinuity is formed at the interface where such physicochemical variables as electrical potential and electrolyte concentration change significantly from the aqueous phase to another phase. Because of the different chemical potentials between the two phases, charge separation often occurs at the interfacial region [1]. This interfacial region, togeter with the charged surface, is usually known as the electrical double layer (EDL) [2]. The structural and electrochemical properties of AAO sensor were investigated for applications in capacitive pH sensors. To change the thickness of the AAO template, the anodizing temperature was varied from $5^{\circ}C$ to $20^{\circ}C$, the thickness of the AAO template invreased from 300 nm to 477 nm. The pH sensitivity of sensors with the anodizing temperature of $20^{\circ}C$ showed the highest value of 56.4 mV/pH in the pH range of 3 to 11. The EDM sensor with the anodizing temperature of $20^{\circ}C$ exhibited the best long-term stability of 0.037 mV/h.

• Journal of Korean Neurosurgical Society
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• v.37 no.4
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• pp.282-286
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• 2005

Objective: Symptomatic chronic subdural hematoma(CSDH) is a well-known neurosurgical entity and most of the lesion is managed by surgical treatment. The authors analyze the surgical indication and the treatment results of twist drill craniostomy with closed-system drainage(TDD) for the symptomatic CSDH. Methods: From March 2001 through December 2003, 31 patients who were treated with TDD for the symptomatic CSDH and followed more than 6months were included. The radiologic criteria of TDD in this study were 1) homogeneous density of hematoma on computed tomography(CT), 2) no septation of hematoma on magnetic resonance imaging(MRI), and 3) thicker hematoma more than twice thickness of skull. Surgical procedures were performed on the maximum thickness of hematoma on CT/MRI. Short and long Steinman pins were used to penetrate the skull and hematoma membrane. As the 5L catheter was inserted through the drill hole, it was kept for 1 - 7days for the drainage of CSDH. The patients of CSDH were followed with clinical symptoms and CT studies. Results: Most of all the 31 patients were improved. However, one patient was suffered from postoperative epidural hematoma and the other patients have received the secondary operation because of the recurrence of CSDH on 3 months after initial surgery. Conclusion: TDD is safe procedure for the symptomatic CSDH if the patients are selected appropriately.