• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.773-783
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• 2007

A simple unbonded-type shear strengthening technique for reinforced concrete beams using wire rope units is developed. Six two-span continuous T-beams externally strengthened with wire rope units and an unstrengthened control beam were tested. The main variables investigated were the amount and prestressing force of wire rope units. All specimens had the same geometrical dimension and arrangement of internal reinforcement. Influence of the distribution of vertical stresses in beam web owing to the prestressing force of wire rope units on the diagonal shear cracking load and the ultimate shear capacity of beams tested is presented. Based on the current study, it can be concluded that the amount and initial prestress of wire rope should be limited to be above 2.5 times the minimum shear reinforcement ratio specified in ACI 318-05 and below 0.6 times its own tensile strength, respectively, to ensure the enhancement of shear capacity and ductile failure mode of the strengthened beams. A numerical analysis based on the upper-bound theorem is developed to assess the shear capacity of continuous T-beams strengthened with wire rope units. From the comparisons of measured and predicted shear capacities, a better agreement is achieved in the proposed numerical analysis than in empirical equations recommended by ACI 318-05.

• Restorative Dentistry and Endodontics
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• v.31 no.2
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• pp.79-85
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• 2006

To evaluate the effect of vital tooth bleaching agent and alcohol pretreatment on dentin bonding, flat dentin windows were produced on the buccal side of the crowns of fifty-five extracted, human premolars. A bleaching gel, $Opalescence^{(R)}$ with 10% of carbamide peroxide (Ultradent Product, USA) was daily applied on the teeth of three experimental groups for six hours for 10 consecutive days, while teeth of a control group were not bleached. After 6 hours of bleaching gel application the specimens were washed and stored in saline until the next day application. After application of $One-step^{(R)}$ dentin bonding agent (Bisco, USA), $Z-250^{(R)}$ resin (3M-ESPE, USA) was bonded to dentin with a mount jig. Shear bond strength was measured with an Instron machine (Type 4202, Instron Corp., USA) after 24 hours. The results were analyzed using one-way ANOVA and Duncan's multiple range test at p < 0.05. Immediate bonding group showed significantly lower bond strength than un-bleached control group (p < 0.05). Ethanol-treated group showed significantly higher bond strength compared to immediate bonding group (p < 0.05). However, the bond strength of the ethanol treatment group was lower than that of the un-bleached control group (p < 0.05). There were no significant difference in shear bond strength between the 2-week delayed bonding group and the ethanol-treated group (p > 0.05) and between delayed bonding group and un-bleached control group (p > 0.05). In the condition of the present study. it seems that alcohol pretreatment after bleaching procedure can reduce the adverse effect of vital bleaching agent on dentin bonding.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.451-460
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• 2010

There are many types of remodeling, however, engineers and architectures preferred to merge two or more separate units to one very spacious unit. Performing this type of remodeling, in the case of wall dominant apartments, requires partial removal of structural wall causing a concern of structural integrity. However, there are insufficient studies about partial removal, that is, openings. Presently, ACI standard have no clear way to evaluate the effect of opening on the structural wall. AIJ has the provision about strength reduction factor '$\gamma$'. However, this reduction factor cannot exactly evaluate the reduction effect of openings because this factor '$\gamma$' was determined through the elastic analysis. Therefore, in this study, 2 structural wall specimens were tested and many test results from previous studies were collected. Using these data, this study performed statistical analysis about strength of structural wall which have the opening in wall panel. And this study performed parametric study verifying shear strength reducing effect by opening area. In the results of statistical study, previous reduction factor show very conservative results because this equation did not consider other factors, reinforcement ratio and aspect ratio of openings, which was affect the shear strength of shear walls. Therefore we performed parametric study based on the test data and suggest new equation for shear strength reduction factor '$\gamma$'.

• Journal of Preventive Medicine and Public Health
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• v.13 no.1
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• pp.13-18
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• 1980

The ultimate goal of treatment of carton monoxide poisoning is to promote dissociation of carboxyhemoglobin and to maintain arterial $PO_2$ above 50mmHg throughout the course of treatment to protect vital organs from damage caused by hypoxia. The hyperbaric chamber designed and manufactured for this purpose has obviousely made an enormous contribution and yet has several handicaps to be overcome by any means. These handicaps are: the financial impact to purchase the chamber (especially in a small, remote community), an extra manpower requirement to operate the device, limitation in the capacity of the chamber (one man type), and the possible hazard of oxygen intoxication and dysbarism. The primary objective of this study is to develope a new therapeutic measure as an alternative to the hyperbaric chamber when it is not available or contraindicated. The effect of intestinal perfusion with hydrogen peroxide has been studied by many investigators and was known to be an excellent way of extrapulmonary oxygen supply. the advantage of this method will include; 1) much more amount of oxygen is delivered to the tissue than one would expect from 100% saturation with oxygen at 1 ata, 2) the procedure is simple and most economical, 3) neither sophisticated equipment nor extra manpower is required. As a study preliminary to the clinical application, authors conducted a series of experiment to observe the effect of hydrogen peroxide enema on dissociation of carboxyhemoglobin in intoxicated rabbit blood. Using an animal gas chamber, 20 rabbits were exposed to CO gas of 6,000 ppm for 60 minutes. Ten rabbits of control group were given 10cc of warmed normal saline solution by reactal perfusion and for the other 10 of the experimental group, the same amount of 1% $H_{2}O_{2}$ solution was given by the same way. Two blood specimens were drawn from each rabbit: the first one immediately following the exposure and the second one after rectal perfusion, about 30 minutes after the first sampling. The result was as follows; 1) The decrease in carboxyhemoglobin concentration during the first 30 minutes in the control and experimental group were $18.18{\pm}4.49%\;and\;23.03{\pm}4.13%$ respectively shelving the significant difference (p<0.05) between the two groups. 2) Hemoglobin and hematocrit value showed no significant difference between two groups and not altered significantly by intestinal perfusion with $H_{2}O_{2}$.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.6
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• pp.511-520
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• 2010

Purpose: This study was conducted in order to compare the efficacy of osseointegration of three different calcium metaphosphate (CMP) coated implants in the rabbit's femur. Materials and Methods: Twenty four rabbits and three different type of CMP coated implants and RBM implants were used in this study. The animals were divided into 4 groups on the basis of implant surface characteristics. Two implants were installed into the condyle of femur of each rabbits. The animals were sacrificed at 2 and 4 weeks after installation. The undecalcified specimens were prepared for histological, radiological examination and histomorphometric analysis of implant-bone contact ratios (BIC) and bone area ratio (BA). Results: Two implants were failed to osseointegrate and implant success rate was 95.2%. There were not any significant inflammatory response in all groups. Fluorescent image at 4 weeks shows that remodeling is slower in RBM group than CMP group. CMP III showed more active remodeling than CMP I, II. In histomorphologic analysis, BIC ratio at 2 weeks was lower than 4 weeks. Conclusion: The results suggest that the ratios of CMP coated implants were higher than that of RBM control group but there is no significantly difference between RBM group and CMP group. In conclusion, CMP coated implant had more clinical availability than RBM implants.

• Journal of Gastric Cancer
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• v.17 no.1
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• pp.52-62
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• 2017

Purpose: The Trastuzumab for gastric cancer (GC) trial identified human epidermal growth factor receptor 2 (HER2) as a predictor of successful treatment with trastuzumab (HER2 receptor targeting agent) among patients with advanced/metastatic GC. To date, the prevalence of HER2 overexpression in the Korean population is unknown. The present study aimed to assess the incidence of HER2 positivity among GC and gastroesophageal (GE) junction cancer samples and the relationship between HER2 overexpression and clinicopathological characteristics in Korean patients. Materials and Methods: Tumor samples collected from 1,695 patients with histologically proven GC or GE junction enrolled at 14 different hospitals in Korea were examined. After gathering clinicopathological data of all patients, HER2 status was assessed by immunohistochemistry (IHC) at each hospital, and IHC 2+ cases were subjected to silver-enhanced in situ hybridization at 3 central laboratories. Results: A total of 182 specimens tested positive for HER2, whereas 1,505 tested negative. Therefore, the overall HER2-positive rate in this study was 10.8% (95% confidence interval=9.3%-12.3%). The HER2-positive rate was higher among intestinal-type cases (17.6%) than among other types, and was higher among patients older than 70 years and 50 years of age, compared to other age groups. Conclusions: Our evaluation of the HER2 positivity rate (10.8%) among Korean patients with GC and GE junction indicated the necessity of epidemiological data when conducting studies related to HER2 expression in GC and GE junction.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.3
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• pp.262-268
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• 2002

Statement of problem. In-Ceram system is one of the all-ceramic crowns that can be used in anterior 3 unit fixed partial dentures and posterior single crowns. The alumina core used in In-Ceram system is manufactured using slip-casting technique. The slip-casting technique is difficult and technique sensitive. To improve this problem, tape-casting method was introduced into dentistry. There were no studies to examine the effect of margin design on the margin fitness of all-ceramic crowns fabricated from alumina tape. Purpose. The purpose of this study was to compare the marginal fitness of glass infiltrated alumina core fabricated from aqueous-based alumina tape according to different margin types ($90^{\circ},\;110^{\circ},\;135^{\circ}$ shoulder margin). Material and method. Three upper central resin incisors were prepared with $90^{\circ},\;110^{\circ}$, and $135^{\circ}$ shoulder margins for all-ceramic crowns, respectively. The resin teeth were duplicated and master die and special plaster die were made as usual. After alumina cores were fabricated from aqueous-based alumina tape, cores were cemented to each 15 epoxy dies replicated from three resin teeth with resin cement. These cemented cores were embedded in epoxy resin. Specimens were cut mesiodistally and buccolingually. Marginal gap and discrepancy were measured under microscope. Results. The marginal gap and discrepancy of $90^{\circ}$ marginal angle was $75.1{\mu}m,\;86.6{\mu}m,\;110^{\circ}$ marginal angle was $41.5{\mu}m,\;50.7{\mu}m$ and $135^{\circ}$ marginal angle was $51.7{\mu}m,\;54.2{\mu}m$, respectively. The smallest value was seen in 110 (angle, which was statistically significant compared to that of $90^{\circ}$ angle (p<0.05). Conclusion. Marginal fitness of alumina cores made of alumina tape with $110^{\circ}$ shoulder margin was best and others were clinically acceptable.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.3
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• pp.296-305
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• 2002

The main disadvantage of cement-retained implant restorations is their difficulty in retrievability. Advocates of cemented implant restorations frequently state that retrievability of the restoration can be maintained if a provisional cement is used. The purpose of this study was to find the optimal properties of provisional luting cements and the surface treatment of abutments in single implant abutment system. 30 prefabricated implant abutments, height 8mm, diameter 6mm, 3-degree taper per side, with light chamfer margins were obtained. Three commercially available provisional luting agents which were all zinc oxide eugenol type ; Cavitec, TempBond and TempBond NE were evaluated. No cement served as the control. TempBond along with vaseline, a kind of petrolatum (2:1 ratio) was also evaluated. Ten out of thirty abutments were randomly selected and abutment surfaces were sandblasted with $50{\mu}m$ aluminum oxide. Another ten abutments were sandblasted with $250{\mu}m$ aluminum oxide. A vertical groove, 1 mm deep and 5mm long was cut in each twenty abutments. Ten of them were sandblasted with $50{\mu}m$ aluminum oxide. The full coverage casting crowns were cemented to the abutments with the designated provisional luting agent. Specimens were stored in distilled water at $37^{\circ}C$ for 24 hours. Each specimen was attached to a universal testing machine. A crosshead speed of 0.5mm/min was used to apply a tensile force to each specimen. Within the limitations of this in vitro study, the following conclusions were drawn: 1. Tensile bond strength of provisional luting cements in no surface treatment decreased with the sequence of TempBond NE, TempBond, Cavitec, TempBond with vaseline, no cement. 2. Tensile bond strength more increased by surface treatment. Sandblasting with $250{\mu}m$ aluminum oxide exhibited the highest tensile bond strength in the abutment cemented with TempBond NE and sandblasting with $50{\mu}m$ aluminum oxide exhibited the highest tensile bond strength in cemented with TempBond. 3. In the aspect of a groove formation, tensile bond strength significantly increased in TempBond with vaseline only and the others had no significant effect on tensile bond strength.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.3
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• pp.314-323
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• 2018

The aim of this study was to evaluate the shear bond strength of three luting cements and to identify the effect of thermocycling. Zirconia discs were made similar to the inner surface of a preformed pediatric zirconia crown ($NuSmile^{(R)}$ ZR crown: ZRCr). The similarity between the zirconia discs and the inner surface of a ZRCr was confirmed by scanning electron microscope. Three luting cements were $Ketac^{TM}$ Cem Permanent Glass Ionomer Luting Cement (KGI), $RelyX^{TM}$ Luting Plus Cement (RLP), $RelyX^{TM}$ Unicem Self-Adhesive Universal Resin Cement (RUR). Three luting cements were bonded according to the manufacturer's instructions for 60 zirconia discs and 60 dentin of primary teeth. Total of 120 specimens were divided into two subgroups: One was not aged, and the other was tested with 5500 thermocycling. Shear bond strength was measured using a universal testing machine, and the fracture patterns were observed with SEM. On the zirconia discs and the dentin of primary teeth, shear bond strength of RUR was higher than that of KGI and RLP, and there were statistically significant differences by cement type. The shear bond strength differences for RUR were not statistically significant depending on thermocycling.

• BMB Reports
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• v.51 no.11
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• pp.584-589
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• 2018

Secondary prevention via earlier detection would afford the greatest chance for a cure in premalignant lesions. We investigated the exomic profiles of non-malignant and malignant changes in head and neck squamous cell carcinoma (HNSCC) and the genomic blueprint of human papillomavirus (HPV)-driven carcinogenesis in oropharyngeal squamous cell carcinoma (OPSCC). Whole-exome (WES) and whole-genome (WGS) sequencing were performed on peripheral blood and adjacent non-tumor and tumor specimens obtained from eight Korean HNSCC patients from 2013 to 2015. Next-generation sequencing yielded an average coverage of $94.3{\times}$ for WES and $35.3{\times}$ for WGS. In comparative genomic analysis of non-tumor and tumor tissue pairs, we were unable to identify common cancer-associated early mutations and copy number alterations (CNA) except in one pair. Interestingly, in this case, we observed that non-tumor tonsillar crypts adjacent to HPV-positive OPSCC appeared normal under a microscope; however, this tissue also showed weak p16 expression. WGS revealed the infection and integration of high-risk type HPV16 in this tissue as well as in the matched tumor. Furthermore, WES identified shared and tumor-specific genomic alterations for this pair. Clonal analysis enabled us to infer the process by which this transitional crypt epithelium (TrCE) evolved into a tumor; this evolution was accompanied by the subsequent accumulation of genomic alterations, including an ERBB3 mutation and large-scale CNAs, such as 3q27-qter amplification and 9p deletion. We suggest that HPV16-driven OPSCC carcinogenesis is a stepwise evolutionary process that is consistent with a multistep carcinogenesis model. Our results highlight the carcinogenic changes driven by HPV16 infection and provide a basis for the secondary prevention of OPSCC.