• Tribology and Lubricants
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• 제31권3호
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• pp.79-85
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• 2015

RC delay is a critical issue for achieving high performance of ULSI devices. In order to minimize the RC delay time, we uses the CMP process to introduce high-conductivity Cu and low-k materials on the damascene. The low-k materials are generally soft and fragile, resulting in structure collapse during the conventional high-pressure CMP process. One troubleshooting method is electrochemical mechanical polishing (ECMP) which has the advantages of high removal rate, and low polishing pressure, resulting in a well-polished surface because of high removal rate, low polishing pressure, and well-polished surface, due to the electrochemical acceleration of the copper dissolution. This study analyzes an electrochemical state (active, passive, transpassive state) on a potentiodynamic curve using a three-electrode cell consisting of a working electrode (WE), counter electrode (CE), and reference electrode (RE) in a potentiostat to verify an electrochemical removal mechanism. This study also tries to find optimum conditions for ECMP through experimentation. Furthermore, during the low-pressure ECMP process, we investigate the effect of current density on surface roughness and removal rate through anodic oxidation, dissolution, and reaction with a chelating agent. In addition, according to the Faraday’s law, as the current density increases, the amount of oxidized and dissolved copper increases. Finally, we confirm that the surface roughness improves with polishing time, and the current decreases in this process.

• Journal of Periodontal and Implant Science
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• 제26권1호
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• pp.27-46
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• 1996

The purpose of this study was designed to compare with the effects of 4 different surface active bioceramics on the healing process of alveolar bone defects in dogs. Artificial alveolar bone defects depth 4-6mm, width 3-4mm) were created with # 6 round bur at interproximal areas of maxillary canine, maxillary 2nd premolar, mandibular canine, and mandibular 3rd premolar. porous hydroxyapatite(Interpore $200^R$) , 45S5 bioglass, CJ4/lOC crystalline glass, and JJ crystalline glass were implanted in intrabony defects randomly. Experimental groups were divided into 4 categories according to its implant material. After implantation, all groups were examined postoperatively 4 weeks to 12 weeks. 3 dogs was selected randomly and sacrificed after vascular perfusion with 2.5% glutaraldehyde at every 4 weeks. Tissue blocks with surroundig alveolar bone and soft tissues were removed and immersed in formaldehyde/glutaraldehyde fixative. After 20 weeks decalcification with EDTA and formic acid, sections were made and observed under light microscope and transmission electron microscope. In all experimental groups, the encapsulation of inactive connective tissue was observed around graft particles in 4 weeks. As time elapsed, the thickness of surrounding connective tissue was decreased. Osteoconductive bone growth pattern was seen apparently in all groups. CJ4/lOC crystalline glass showed the most active bone formation until 8 weeks. 45S5 bioglass was, however, the most active in new bone formation at 12 weeks. Though there was difference in resorption rate among grafting materials, the size of graft particles was decreased gradually. 45S5 bioglass was resorbed faster than the others. On the other hand, porous hydroxyapatite was degraded most slowly. Phagocytosed particulate matters was observed in the cytoplasm of multinuclear multinuclear giant cell and macrophage under transmission electron microscope. The results suggested suggested that 45S5 bioglass and CJ4/lOC crystalline glass may have some enhanced reparative potential when compared to porous hydroxapatite in the treatment of periodontal defeds. JJ crystalline glass reguires a further investigation of the safety of its use.

• Journal of Periodontal and Implant Science
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• 제26권1호
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• pp.1-26
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• 1996

This study was performed to estimate the effects of cultured bone cell inoculated on porous type hydroxyaptite for the regeneration of the artificial alveolar bone defect. In this experiment 3 beagle dogs were used, and each of them were divided into right and left mandible. Every surgical intervention were performed under the general anesthesia by using with intravenous injection of Pentobarbital sodium(30mg/Kg). To reduce the gingival bleeding during surgery, operative site was injected with Lidocaine hydrochloride(l:80,000 Epinephrine) as local anesthesia. After surgery experimental animal were feeded with soft dietl Mighty dog, Frisies Co., U.S.A.) for 1 weeks to avoid irritaion to soft tissue by food. 2 months before surgery both side of mandibular 1st premolar were extracted and bone chips from mandibular body were obtained from all animals. Bone cells were cultured from bone chips obtained from mandible with Dulbecco's Modified Essential Medium contained with 10% Fetal Bovine Serum under the conventional conditions. Porous type hydroxyapatite were immerse into the high concentrated cell suspension solution, and put 4 hours for attachin the cells on the surface of hydroxyapatite. Graft material were inserted on the artificial bone defect after 3 days of culture. Before insertion of cellinoculated graft material, scanning electronic microscopic observation were performed to confirm the attachment and spreading of cell on the hydroxyapatite surface. 3 artificial bone defects were made with bone trephine drill on the both side of mandible of the experimental animal. First defect was designed without insertion of graft material as negative control, second was filled with porous replamineform hydroxyapatite inoculated with cultured bone marrow cells as expermiental site, and third was filled with graft materials only as positive control. The size of every artificial bone defect was 3mm in diameter and 3mm in depth. After the every surgical intervention of animals, oral hygiene program were performed with 1.0% chlorhexidine digluconate. All of the animals were sacrificed at 2, 4, 6 weeks after surgery. For obtaining histological section, tissus were fixed in 10% Buffered formalin and decalcified with Planko - Rycho Solution for 72hr. Tissue embeding was performed in paraffin and cut parallel to the surface of mandibular body. Section in 8um thickness of tissue was done and stained with Hematoxylin - Eosin. All the specimens were observed under the light microscopy. The following results were obtained : 1. In the case of control site which has no graft material, less inflammatory cell infiltration and rapid new bone forming tendency were revealed compared with experimental groups. But bone surface were observed depression pattern on defect area because of soft tissue invasion into the artificial bone defect during the experimental period. 2. In the porous hydroxyapatite only group, inflammatory cell infiltration was prominet and dense connective tissue were encapsulated around grafted materials. osteoblastic activity in the early stage after surgery was low to compared with grafted with bone cells. 3. In the case of porous hydroxyapatite inoculated with bone cell, less inflammatory cell infiltration and rapid new bone formation activity was revealed than hydroxyapatite only group. Active new bone formation were observed in the early stage of control group. 4. The origin of new bone forming was revealed not from the center of defected area but from the surface of preexisting bony wall on every specimen. 5. In this experiment, osteoclastic cell was not found around grafted materials, and fibrovascular invasion into regions with no noticeable foreign body reaction. Conclusively, the cultured bone cell inoculated onto the porous hydroxyapatite may have an important role of regeneration of artificial bone defects of alveolar bone.

• Journal of Gastric Cancer
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• 제12권4호
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• pp.237-242
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• 2012

Purpose: Despite the great advances in laparoscopic techniques, most active general surgeons do not apply laparoscopic surgery in the treatment of duodenal ulcer perforation when facing a real-life emergency. Therefore, our study was designed to evaluate the feasibility of laparoscopic surgery in duodenal ulcer perforation, and provide a step-by-step protocol with tips and recommendations for less experienced surgeons. Materials and Methods: Between March, 2011 and May, 2012, 21 patients presenting with duodenal ulcer perforation underwent laparoscopic primary repair with omentopexy. There were no contraindications to perform laparoscopic surgery, and the choice of primary repair was decided according to the size of the perforation. The procedure for laparoscopic primary repair with omentopexy consisted of peritoneal lavage, primary suture, and omentopexy using a knot pusher. Results: During the operation, no conversion to open surgery or intra-operative events occurred. The median operation time was 45.0 minutes (20~80 minutes). Median day of commencement of a soft diet was day 6 (4~17 days). After surgery, the median hospital stay was 8.0 days (5~27 days). Postoperative complications occurred in one patient, which included a minor leakage. This complication was resolved by conservative management. Conclusions: Although our study was carried out on a small number of patients at a single institution, we conclude that laparoscopic primary repair can be an effective surgical method in the treatment of duodenal ulcer perforation. We believe that the detailed explanation of our procedure will help beginners to perform laparoscopic primary repair more easily.

• 대한족부족관절학회지
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• 제8권2호
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• pp.166-170
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• 2004

Purpose: To evaluate the results of MIPPO (minimal invasive percutaneous plate osteosynthesis) technique for distal tibial metaphyseal fractures. Materials and Methods: It is a retrospective study of 13 patients who were treated by MIPPO technique for distal tibial metaphyseal fractures from Jan. 2001 to Jan. 2003. The average age was 46.7 years and mean follow-up period was 13.3 months. According to AO classification, there were 8 cases of A1, 3 cases of A2, 1 case of B1 and 1 case of C2. One case of A1 was a Gustilo-Anderson type I open fracture and fibular fractures were combined in 12 cases. We applied anatomical reduction and internal fixation for the fibular fractures and internal fixation on the medial side of the tibia by MIPPO technique for distal tibial metaphyseal fractures. Clinical results were evaluated using radiographic results, Neer score, the starting time of postoperative exercise and clinical complications. Results: According to the Neer score, all cases showed satisfactory results. Active ankle ROM was started at average 2.4 weeks ($2{\sim}4$ weeks) and full weight bearing ambulation at average 5.2 weeks ($4{\sim}8$ weeks) postoperatively. Union of fractures was obtained by average 14.4 weeks ($8{\sim}18$ weeks) postoperatively. Two cases showed $5^{\circ}$ limitation of motion without functional deficits and other cases showed satisfactory ROM results. One case had $6^{\circ}$ valgus deformity without functional deficits. There were not any other complications like soft tissue problems and delayed-or non-union. Conclusion: MIPPO technique for the treatment of distal tibial metaphyseal fractures is a feasible technique with a good clinical outcomes.

• Applied Microscopy
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• 제3권1호
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• pp.29-38
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• 1973

Introduction. The human cutaneous scars manifest themselves many ways in different types according to the factors such as the age, sex, race of the patient as well as the location,. kind and heal ing process of the wound. Among the scars it is quiet difficult to verify the clinical course of the hypertrophic or keloidal scars from the true keloids. However, clinical observations indicate that stress, either mechanical or in the forms of chronic infections, can induce a functional change in the fibroblasts causing an excessive production of collagenous matrix. In this study, we preliminary attempt to justify any difference of the cellular structure between keloids and hypertrophic scars by using electron microscope. Material and Methods. A total of 23 cases: 2 scars, 2 hypertrophic scars and 19 keloids are examined. Immediately, the biopsy tissue was fixed in 10% neutral formalin and 4% glutaraldehyde solution in phosphate buffer for 4 hours, post fixed in 1 % osmium tetraoxide for two hours, dehydrated with graded alcohol, and embedded in Epon 812. Thick sections were stained with hematoxylin eosin, periodic acid-Schiff(PAS) and Van Gieson stain. Thin sections were cut and uranyle acetate, lead citratestain and examined with the electron microscope. Result. The morphologic features of keloid showed thick, homogenously eosinophilic bands of collagen and numberous large active fibroblasts. The hypertrophic scar and soft scar are more cellular than keloid and composed thinner collagenous fiber. For this paper in the etiology of keloids can not as be defined, but and interesting keloidal tissue fibroblast showed irregular nucleus with irregular shape dense bodies and fibril materials contained in to the cytoplasm.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제16권3호
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• pp.499-507
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• 1994

The aim of this experiment is to compare the healing process of extraction sockets after immediate implant placement with those using autogenous bone grafts and guided tissue regeneration with Gore-Tex. The first lower premolars and the second premolars of six experimental dogs were extracted and Stryker fin type implants were placed into the extraction sockets immediately after extraction. In the control group, any graft materials were'not used and the dead space around implants was left in itself and covered with only periosteum. In the experimental group A, implants were covered with Gore tex without any bone grafts, and in the experimental group B, the dead space around implants was filled with the bone chips gained from drilling procedure. Each experimental dogs were sacrificed at the 1st, 2nd, 3rd, 6th, and 8th week and the specimens were observed by gross examination, radiological examination, and light microscopic examination. The following results were obtained. 1. Well healed soft tissue and no mobility of the implants were observed in control and two experimental groups. 2. In the radiogical examination, radiopacity around implants had been increased gradually. 3. In the microscopic examination, there were good healing process and active new bone formation in both in the experimental groups, Especially the more amount of new bone formation occurred in the experimental group B using bone chips. 4. Bone chip grafts and guided tissue regeneration (GTR) using Gore-Tex may be one of the successful methods in the immediate implantation.

• Journal of Advanced Marine Engineering and Technology
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• 제39권8호
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• pp.843-848
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• 2015

The objective of this study is to observe and optimize a typical ocean environment and reduce wave reflections in the wave flume. In order to generate ocean waves in the wave flume, a combination of a horizontal piston type wave generator and wave absorbers was installed in the channel. Two probes for measuring the wave heights, i.e., wave level gauges, were used to record the continuous variation of the wave surface, the phase difference, and the maximum (crest) and minimum (trough) points of the propagating waves. In order to optimize the shape and size of the propagating waves, several absorption methods were proposed. Apart from an active wave absorption method, we used methods that involved vertical porous plates, horizontal punching plates, and sloping-wall-type wave absorbers. To obtain the best propagating waves, a sloping-wall-type wave absorber was chosen and tested in terms of the constitutive filling materials and the location and shape of the plate. This study also focused on the theoretical prediction of the wave surface, separating them into the incident and reflective components. From the results, it is evident that the wave absorber comprising a hard filling material exhibits a better performance than the absorber comprising a soft material, i.e., the wave absorber can be a strong sink to control the energy of the incoming wave. In addition, larger wave absorbers correspond to lower reflectance because a larger volume can reduce the incoming wave energy. Therefore, at constant absorber conditions, the reflectance of the wave increases as the wave period increases. Finally, the reflectance of the wave was controlled to be less than 0.1 in this study so that the wave flume can be used to simulate an offshore environment.

• 자원환경지질
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• 제30권4호
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• pp.327-340
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• 1997

Geochemical characteristics of groundwater, based on chemical analyses of 54 water samples, differ among main rocks of Haman formation, Panyawoel formation, andesite and granite in Daegu area in relation to mineralogical and chemical compositions of the rocks. Concentrations of most solutes are higher in groundwaters of Haman and Panyawoel formations than in those of andesite and granite. High concentrations of $Ca^{2+}$ and $Mg^{2+}$ in groundwaters of the sedimentary rocks result mainly from reaction of $CO_2$-charged water with calcite and weathered feldspars. Average groundwaters in the sedimentary rocks are oversaturated with respect to calcite. Major types of groundwaters are hard $Ca(HCO_3)_2$ and $CaSO_2-CaCl_2$ with hardness of 442 mg/l for Haman formation and 275 mg/l for Panyawoel formation whereas they are soft $Ca(HCO_3)_2$ with hardness 35 mg/I for andesite and 39 mg/I for granite. $Ca(HCO_3)_2$ type results mainly from calcite-dissolution and $CaSO_4-CaCl_2$ from pyrite and partly from domestic pollutants. $CaSO_4-CaCl_2$ type may indicate that groundwaters in the sedimentary rocks are more evolved geochemically than those in the igneous rocks, but it is not obvious because the type might be affected by pyrie dissolution and domestic pollutions. Acid rain is buffered by active calcite in the sedimentary rocks. In the igneous rocks acid rain might react with gibbsite and other forms of $Al(OH)_3$ that might have accumulated as weathering products of primary silicates, and is buffered.

• 대한가정학회지
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• 제26권2호
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• pp.39-47
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• 1988

The aim of this study is to grasp the actual state of high school girls' clothing after liberalization of their uniform and to provide the reasonable guidance materials in clothing for both schools and homes. These are the results of the study 1. In the aspect of the favor of clothing and the interest in about clothes. a. They were fond of wearing "T" shirts, blue jeans in summer and pants and jackets in spring as their school wear. That implies that they enjoy wearing active and practical clothes. b. In the aspect of color, majority of them favored blue or similar colors, Also they had the tendency to love soft, simple clothe and more students preferred cloth without pattern. c. In their choice of them, they seldom paid attention to the informative-label are not their chief interest. d. More than half of girls prepare one or two suits in advance in a season, and they would prepare them deliberately This implies that their everyday life inclothing is based on the economic motive. 2. In the aspect of the purchasing clothes, a. Most of the girls bought them at the market and some of them at the direct-sales stall. b. when they purchased clothes, most girls were accompanied by their/mother and senior girls more often by their friends. c. The price and kinds of their favorite clothes such as "T" shirts and blouse was 5,000 won or so, and skirts, pants, one-piece and jackets are from the range of 5,000 won to below 10,000 won mostly. d. In regard to so-called brand-name items by popular designers, half of the girls responded that they wear some of such kinds of items because of superiority of sewing and longterm wearing, and the other half tend not to wear them due to high price.