• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.13-23
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• 2006

The sinkhole and leakage in dam core were detected at one of earth fill dams in Korea. The damage areas in the core of the dam were repaired by compaction grouting method. This study is to evaluate compaction grouting activity by in-situ and laboratory experiments before, during and after the remedial work. The intensive site investigation and geophysical survey were conducted during and after the compaction grouting work. The compaction grouting work was carried out for the damaged dam core between June 16 and August 24, 2000. The leakage reduction generally occurred in the core of the dam after the remedial work. The use of compaction grouting was considered the proper countermeasures for repairing the damaged dam. It shows that the loose or voided zones have been properly filled and the leakage has been reduced by about 96% of that before the treatment of the remedial work performed at dam core by compaction grouting.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.5
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• pp.463-474
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• 2009

Double symmetric patch repair of existing structures always causes membrane action only, however, in many cases this technique is not practical. On the other hand, the bending stiffness of the patch and the skin increases as tensile loading is increased and affects the bending deformation significantly in the case of single-sided patch repair. In this study, the p-convergent full layerwise model has been proposed to determine the stress concentration factor in the vicinity of a circular hole as well as across the thickness of plates with single-sided patch repair. In assumed displacement field, the strain-displacement relations and 3-D constitutive equations of a layer are obtained by the combination of 2-D and 3-D hierarchical shape functions. The transfinite mapping technique has been used to represent a circular boundary and Gauss-Lobatto numerical integration is implemented in order to directly obtain stresses occurred at the nodal points of each layer without other extrapolation techniques. The accuracy and simplicity of the present model are verified with comparison of the previous results in literatures using experiment and conventional 3-D finite element. Also, the bending effect has been investigated with various patch types like square, circular and annular shape.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.2
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• pp.89-96
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• 2018

Purpose: The aim of this study was to evaluate the effect of delayed time, surface treatment, and repair materials on repair of bis-acryl composite resin through comparison of shear bond strength and to evaluate the utility of bis-acryl composite resin repair using polymethyl methacrylate resin. Materials and Methods: A total of 90 bis-acryl composite resin specimens were fabricated and classified into 9 test groups, each of 10 pieces according to delayed time, surface treatment and repair material. The shear bond strength of each specimen was measured using a universal testing machine immediately after fabrication and analyzed using a statistical analysis program (IBM SPSS statistics 20). After the shear bond strength measurement, the fracture surface of the specimen was observed. Results: The highest shear bond strength ($17.54{\pm}3.14MPa$) was observed in the experimental group bonded immediately with a light-curing flowable composite resin using a bonding agent. Conclusion: When repairing bis-acryl composite resin, it is necessary to consider whether to remake according to the delayed time. For effective repair, it is desirable to consider appropriate materials and surface treatment methods according to the site or purpose of use.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.156-165
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• 1999

The purpose of this study was to evaluate the effect of surface treatments on the shear bond strength between new and old composites. Circular cavities prepared on the center of acrylic resin mold and the prepared cavities were filled with composite resin. They randomly assigned into control group and 8 groups according to the difference in surface treatments of old composites; Control group: no surface treatment, Group 1: surface treated with #120 SiC paper & bonding agent, Group 2: surface treated with #400 SiC paper & bonding agent, Group 3: surface treated with #120 SiC paper, 32% $H_3PO_4$ & bonding agent, Group 4: surface treated with #400 SiC paper, 32% $H_3PO_4$ & bonding agent, Group 5: surface treated with #120 SiC paper, primer & bonding agent, Group 6: surface treated with #400 SiC paper, primer & bonding agent, Group 7: surface treated with #120 SiC paper, 32% $H_3PO_4$, primer & bonding agent, Group 8: surface treated with #400 SiC paper, 32% $H_3PO_4$, primer & bonding agent. New composites were applicated on the old composites of experimental groups. The shear bond strengths for the experimental specimen were measured and the results were analyzed by using one way ANOVA. The observations of surface morphology after SiC paper roughening and debonded surface morphology after shear bond strength test were done by SEM. The results were as follows; 1. Shear bond strengths for specimens roughened with #120 SiC paper matching with the particle size of coarse diamond bur were significantly higher than those for the specimens with #400 SiC paper(P<0.05). By SEM, the surface of the specimens roughened with #120 SiC paper was more irregular than the specimens with #400 SiC paper. 2. Shear bond strengths for specimens treated with 32% $H_3PO_4$ etchant, primer, bonding resin were significantly higher than those for specimens treated with 32% $H_3PO_4$ and bonding resin(P<0.05). 3. Shear bond strengths for the specimens treated with 32% $H_3PO_4$ etchant and bonding resin were significantly higher than those for specimens treated with only bonding resin(P<0.05). There was no remarkable change of surface morphology after 32% $H_3PO_4$ etching. 4. It was possible to observe mixed fracture patterns (the cohesive fracture of old composite and the adhesive fracture between old and new composite) in the specimens roughened with #120 SiC paper, but almost adhesive fracture in the specimens roughened with #400 SiC paper.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.193-202
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• 2016

Purpose: This study was performed in order to assess the effect of the surface treatment methods and the use of bonding agent on the shear bond strength (SBS) between the aged CAD-CAM (computer aided design-computer aided manufacturing) hybrid materials and added composite resin. Materials and methods: LAVA Ultimate (LU) and VITA ENAMIC (VE) specimens were age treated by submerging in a $37^{\circ}C$ water bath filled with artificial saliva (Xerova solution) for 30 days. The surface was ground with #220 SiC paper then the specimens were divided into 9 groups according to the combination of the surface treatment (no treatment, grinding, air abrasion with aluminum oxide, HF acid) and bonding agents (no bonding, Adper Single Bond 2, Single Bond Universal). Each group had 10 specimens. Specimens were repaired (added) using composite resin (Filtek Z250), then all the specimens were stored for 7 days in room temperature distilled water. SBS was measured and the fractured surfaces were observed with a scanning electron microscope (SEM). One-way ANOVA and Scheffe test were used for statistical analysis (${\alpha}=.05$). Results: Mostly groups with bonding agent treatment showed higher SBS than groups without bonding agent. Among the groups without bonding agent the groups with aluminum oxide treatment showed higher SBS. However there was no significant difference between groups except two subgroups within LU group, which revealed a significant increase of SBS when Single Bond Universal was used on the ground LU specimen. Conclusion: The use of bonding agent when repairing an aged LAVA Ultimate restoration is recommended.

• Journal of Periodontal and Implant Science
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• v.29 no.3
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• pp.483-509
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• 1999

Biodegradable barrier membrane has been demonstrated to have guided bone regeneration capacity on the animal study. The purpose of this study is to evaluate the effects of cultured calvarial cell inoculated on the biodegradable barrier membrane for the regeneration of the artificial bone defect. In this experiment 35 Sprague-Dawley male rats(mean BW 150gm) were used. 30 rats were divided into 3 groups. In group I, defects were covered periosteum without membrane. In group II, defects were repaired using biodegradable barrier membrane. In group III, the defects were repaired using biodegradable barrier membrane seeded with cultured calvarial cell. Every surgical procedure were performed under the general anesthesia by using with intravenous injection of Pentobarbital sodium(30mg/Kg). After anesthesia, 5 rats were sacrificed by decapitation to obtain the calvaria for bone cell culture. Calvarial cells were cultured with Dulbecco's Modified Essential Medium contained with 10% Fetal Bovine Serum under the conventional conditions. The number of cell inoculated on the membrane were $1{\times}10^6$ Cells/ml. The membrane were inserted on the artificial bone defect after 3 days of culture. A single 3-mm diameter full-thickness artificial calvarial defect was made in each animal by using with bone trephine drill. After the every surgical intervention of animal, all of the animals were sacrificed at 1, 2, 3 weeks after surgery by using of perfusion technique. For obtaining histological section, tissues were fixed in 2.5% Glutaraldehyde (0.1M cacodylate buffer, pH 7.2) and Karnovsky's fixative solution, and decalcified with 0.1M disodium ethylene diaminetetraacetate for 3 weeks. Tissue embeding was performed in paraffin and cut parallel to the surface of calvaria. Section in 7${\mu}m$ 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 . During the whole period of experiment, fibrous connective tissue was revealed at 1week after surgery which meant rapid soft tissue recovery. The healing rate of defected area into new bone formation of the test group was observed more rapid tendency than other two groups. 2 . The sequence of healing rate of bone defected area was as follows ； test group, positive control, negative control group. 3 . During the experiment, an osteoclastic cell around preexisted bone was not found. New bone formation was originated from the periphery of the remaing bone wall, and gradually extended into central portion of the bone defect. 4 . The biodegradable barrier membrane was observed favorable biocompatibility during this experimental period without any other noticeable foreign body reaction. And mineralization in the newly formed osteoid tissue revealed relatively more rapid than other group since early stage of the healing process. Conclusively, the cultured bone cell inoculated onto the biodegradable barrier membrane may have an important role of regeneration of artificial bone defects of alveolar bone. This study thus demonstrates a tissue-engineering the approach to the repair of bone defects, which may have clinical applications in clinical fields of the dentistry including periodontics.

• Composites Research
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• v.31 no.3
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• pp.88-93
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• 2018

In this study, damaged composite laminates were repaired by a stepped patch repair method using halloysite nanotube(HNT) and milled carbon(MC) reinforced composite materials with different amount of the particles. And the mechanical and structural effects of the particles on the interface between the damaged and repair surfaces were analyzed. At this time, after exposing them to a harsh environment of high temperature and humidity for a long time, the recovery rate of the material properties relative to the material forming the damaged plate was compared. As a result, at $70^{\circ}C$ high temperature distilled water, the hygroscopicity of the HNT/GFRP composites was significantly different from that of the MC/GFRP composites. Especially, 0.5, 1 wt. % HNT was added, the moisture absorption rate was the lowest and this was the factor that contributed to the mechanical strength increase. On the other hand, MC showed a high hygroscopic resistance only with a small amount, and the strength was different according to the action direction of the load, and the addition amount was also different.

• Journal of Life Science
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• v.18 no.2
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• pp.200-205
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• 2008

The purpose of this study is to investigate the effects of the herbal Chokong pill (hereafter HCKP) on the liver cell and enzyme activities of serum in rat. HCKP were mixed with pickled black soybeans and five different kinds of medicinal herbs (Rhynchosia nulubilis, Glycyrrhiza uralensis, Zizyphus vulgaris, Atractylodes macrocephala K., Astragalus membranaceus and Cornus officinalis). Four groups of male Sprague-Dawley rats were fed by different diets for 9 weeks: normal diet (Nor), high-fat diet (HF), high-fat diet supplemented with 1% (T1) and 5% (T5) HCKP powder, respectively. Depending on the presence of HCKP in high fat diet, the activities of the blood serum GOT and GPT were decreased. GOT and GPT activities of T1 and T5 were decreased 6.1%, 17.8% and 25.4%, 32.4% compared with HF. On microstructure observing through the transmission electron microscope (TEM) of liver cell, in normal group, a normal large and clear nucleus, rough endoplasmic reticulum (RER) and mitochondria possessing well-defined double outer-limiting membranes were found. However, in HF, it was hard to observe the microstructures in cytoplasm, because of too many fat granules. It showed severely damaged cell, pyknotic nucleus, swollen disintegrating RER and mitochontria loosing the cristae. In T1, there were more repaired liver cells and less fat granules than HF. In T5, there were much less numbers and smaller size of the fat granules than T1, and the morphology was similar to normal cell.

• Journal of Korean Academy of Nursing
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• v.4 no.3
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• pp.93-104
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• 1974

Regardless of a patient's diagnosis, the care of his skin has been a primary concern of nurses throughout the years. Nurses has washed, dried, and rubbed the skin and have changed his position so as to keep the patient's skin in good condition and to protect him from pressure sores. However, we still find many-patients suffering from the pressure sores which may take many mothers or years of treatment and cost a lot to be repaired. In view of expensive cost for treatment of the sores and low ratios of nursing staff per patient for intensive nursing care, prophylaxis of the bed sores with sufficient aids is extremely important both for patients and for nurses. Therefore, the unique purpose of this study was to determine whether sponge is good enough to treat and prevent the pressure sore as compared with gel pad and sheepskin. Sixty patients in the age range of 15 through 45 who were in unconscious status or have difficulty of mobility were chosen between January and March of 1974 at Seoul National University Hospital. They were randomly assigned to each treatment and observed on every 4th day with regard to level of consciousness, status of mobility, moisture or dryness of the bed, general skin condition, intake of nutrition, vital signs and intervals of position change in comparison with the changes of skin over the bony prominences. The study results were reviewed in a statistical method analysis of valiance-to obtain the following findings: 1. There was no significantly different changes of skin over the sanctum or the trochanter in each group using get pad, sheepskin or sponge. It means that we may substitute sponge for expensive gel pad or sheepskin. 2. There was no significant difference among mean changes of patient's skin in relation to sheepskin, gel pad and sponge. 3. There was no significant changes of patient's akin in relation to level of consciousness, status of mobility, intake of nutrition, general skin condition, temperature, blood pressure or interval of position change. 4. There were no meaningful interactions between each treatment and level of consciousness, moisture or dryness of the bed, intake of nutrition, general skin condition, temperature or blood pressure. 5. Sheepskin and gel pad had significantly better influence on patients with limited mobility than on patients with immobility, and sponge on patients with immobility on than patients with limited mobility, 6. Sheepskin and sponge had meaningfully totter influence on patients changing position at below 2-hour interval, gel pad at 2-4-hour interval, sheepskin at 4-6-hour interval, and three of them at above 6-hour interval.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.3 no.1
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• pp.21-25
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• 2010

Purpose: To evaluate efficacy of ultrasound guided prolotherapy in patients with persistant symptoms after rotator cuff repair. Materials and Methods: Between January and December of 2008, 90 patients who had persistant pain and shoulder adhesion 4 weeks after rotator cuff repair were treated with ultrasound guided prolotherapy. The mean age was 55.2 years. Visual analogue scale (VAS) and range of motion (ROM) before and after the procedure, complications related to the procedure were analyzed. Results: The average VAS score at 4 weeks follow up decreased to $2.5{\pm}2.304$ from $6.3{\pm}1.25$ before prolotherapy and forward flexion range at 4 weeks follow up increased to $143{\pm}26.63$ from $106{\pm}21.64.$ Four weeks after the ultrasound guided prolotherapy, 74 cases(82%) reported of improved pain and ROM, 13 cases(14%) reported of improvement after 2~5 days of the procedure and 3 cases(4%) had no improved in pain and ROM. No complications were encountered. Conclusion: The authors believe that ultrasound guided prolotherapy in repaired rotator cuff tear patients theoretically increased possibilities of healing and with relieving the pain of the patients results in increased possibility of rehabilitation effect.