• Tuberculosis and Respiratory Diseases
• /
• v.41 no.5
• /
• pp.484-488
• /
• 1994

Background : The antigen-specific receptor on the surface of most peripheral T lymphocytes is a disulfide-linked heterodimer composed of $\alpha$ and $\gamma$ subunits, noncovalently associated with CD3 polypeptides. Recently, a novel type of CD3-associated heterodimer was described on a T cell subset that does not express CD4 or CD8 molecules. This second type of TCR dimer is composed of chains encoded for by the $\gamma$- and $\delta$-TCR genes. These cells may exert both cytotoxic and lymphokine producing functions. Although it was reported that some ${\gamma}{\delta}$-TCR might recognize an MHC-linked determinant, the funεtion or physiologic ligand for this new receptor is not yet clear. It was found that ${\gamma}{\delta}$-TCR can react with 65 kD heat shock protein of M. tuberculosis, which suggests the possible protective role of ${\gamma}{\delta}$ T lymphocytes against tuberculosis. In our previous study, there was neither the increase in number nor the functional activation of ${\gamma}{\delta}$ T cells in the peripheral blood from patients with pulmonary tuberculosis. Now we report the distribution of ${\gamma}{\delta}$ T cells in the regional sites of M. tuberculosis infection, especial1y tuberculous lymphadenitis. Methods : Lymph nodes from patients with pathologically-proven tuberculous lymphadenopathy (n=5) and reactive hyperplasia (n=3) were used. Tissues were frozen in liquid nitrogen immediately after removal and stored below $-70^{\circ}C$. The cryostat sections of these frozen specimens were stained with anti-Leu-4 Ab, Identi-T TCR ${\delta}1$, and Identi-T ${\beta}F1$. The number of positively stained cells were counted at high power field. Results : The infiltration of ${\gamma}{\delta}$ T cells was significantly higher in the lymph nodes from patients with tuberculous lymphadenopathy than that with reactive hyperplasia ($16.3{\pm}10.3%$ vs. $1.7{\pm}1.5%$). Conclusion : These results suggest that ${\gamma}{\delta}$) T cells may play a role in the defense against M. tuberculosis infection, especially in the regional sites of infection.

• The Journal of Korean Academy of Prosthodontics
• /
• v.47 no.4
• /
• pp.424-434
• /
• 2009

Statement of problem: Problems such as loosening and fractures of retained screws and fracture of implant fixture have been frequently reported in implant prosthesis. Purpose: Implant has weak mechanical properties against lateral loading compared to vertical occlusal loading, and therefore, stress analysis of implant fixture depending on its material and geometric features is needed. Material and methods: Total 28 of external hexed implants were divided into 7 of 4 groups; Group A (3i, FULL $OSSEOTITE^{(R)}$Implant), Group B (Nobelbiocare, $Br{\aa}nemark$ $System^{(R)}$Mk III Groovy RP), Group C (Neobiotec, $SinusQuick^{TM}$ EB), Group D (Osstem, US-II). The type III gold alloy prostheses were fabricated using adequate UCLA gold abutments. Fixture, abutment screw, and abutment were connected and cross-sectioned vertically. Hardness test was conducted using MXT-$\alpha$. For fatigue fracture test, with MTS 810, the specimens were loaded to the extent of 60-600 N until fracture occurred. The fracture pattern of abutment screw and fixture was observed under scanning electron microscope. A comparative study of stress distribution and fracture area of abutment screw and fixture was carried out through finite element analysis Results: 1. In Vicker's hardness test of abutment screw, the highest value was measured in group A and lowest value was measured in group D. 2. In all implant groups, implant fixture fractures occurred mainly at the 3-4th fixture thread valley where tensile stress was concentrated. When the fatigue life was compared, significant difference was found between the group A, B, C and D (P<.05). 3. The fracture patterns of group B and group D showed complex failure type, a fracture behavior including transverse and longitudinal failure patterns in both fixture and abutment screw. In Group A and C, however, the transverse failure of fixture was only observed. 4. The finite element analysis infers that a fatigue crack started at the fixture surface. Conclusion: The maximum tensile stress was found in the implant fixture at the level of cortical bone. The fatigue fracture occurred when the dead space of implant fixture coincides with jig surface where the maximum tensile stress was generated. To increase implant durability, prevention of surrounding bone resorption is important. However, if the bone resorption progresses to the level of dead space, the frequency of implant fracture would increase. Thus, proper management is needed.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.5
• /
• pp.479-487
• /
• 2023

Recently, the destructive power of typhoons is continuously increasing owing to global warming. In a situation where the installation of floating wind turbines is increasing worldwide, concerns about the huge loss and collapse of floating offshore wind turbines owing to strong typhoons are deepening. A new type of disconnectable mooring system must be developed for the safe operation of floating offshore wind turbines. A new submersible mooring pulley considered in this study is devised to more easily attach or detach the floating of shore wind turbine with mooring lines compared with other disconnectable mooring apparatuses. To investigate the structural safety of the initial design of submersible mooring pulley that can be applied to an 8MW-class floating type offshore wind turbine, scale-down structural models were developed using a 3-D printer and structural tests were performed on the models. For the structural tests of the scale-down models, tensile specimens of acrylonitrile butadiene styrene material that was used in the 3-D printing were prepared, and the material properties were evaluated by conducting the tensile tests. The finite element analysis (FEA) of submersible mooring pulley was performed by applying the material properties obtained from the tensile tests and the same load and boundary conditions as in the scale-down model structural tests. Through the FEA, the structural weak parts on the submersible mooring pulley were reviewed. The structural model tests were conducted considering the main load conditions of submersible mooring pulley, and the FEA and test results were compared for the locations that exceeded the maximum tensile stress of the material. The results of the FEA and structural model tests indicated that the connection structure of the body and the wheel was weak in operating conditions and that of the body and the chain stopper was weak in mooring conditions. The results of this study enabled to experimentally verify the structural safety of the initial design of submersible mooring pulley. The study results can be usefully used to improve the structural strength of submersible mooring pulley in a detailed design stage.

• Journal of the Korean earth science society
• /
• v.33 no.2
• /
• pp.126-138
• /
• 2012

Ultrasonic method is widely used for the evaluation of weathering index and of degree of deterioration because it is easily applicable $in$ $situ$. The basic idea of the method is that the ultrasonic velocity decreases as a rock is being weathered. Thus, the difference of ultrasonic velocities between fresh rock and weathered rock indicates the degree of weathering. In this method, the ultrasonic velocity of fresh rock is assumed to be 5,000 m/s. However, this assumption can cause significant errors in estimating weathering index, especially in case that those rocks of the same type have a wide range of ultrasonic velocities such as in Korea. Therefore, we obtained twenty rock specimens and sixty core samples commonly used for stone cultural heritages in Korea, and measured ultrasonic velocities. From the results, we found that the ultrasonic velocities of the same rock type, granite samples range from 3,118 to 5,380 m/s, and that the estimated weathering index can be highly biased if we use the fixed value of 5,000 m/s. We created a database (DB) by combining the measurement data and reported it. We also measured ultrasonic velocities by direct and indirect methods to quantify the calibration coefficient for each sampling site. We found that the calibration coefficients vary widely from site to site (1.31-1.76). Other factors, such as operator bias and temperature did not show any significant effect on errors in ultrasonic velocity measurements. Lastly, we applied our ultrasonic velocity DB and calibration coefficients to a stone cultural heritage, Bonghwang-ri Buddha statue. Our estimation of the weathering index was 0.3, 0.1 smaller than that by conventional method. The degree of deterioration was also different, "moderately weathered", while conventional method gave "highly weathered". Since other independent studies reported that the degree of deterioration of the Buddha statue was "moderately weathered", our estimation seems to be more accurate. Thus our method can help accurately evaluate the weathering index and the conservation planning for a stone cultural heritage.

• Journal of Veterinary Clinics
• /
• v.28 no.5
• /
• pp.486-496
• /
• 2011

A special mesenchymal tissue layer called perichondrium has a chondrogenic capacity and is a candidate tissue for engineering of cartilage. To overcome limited potential for chondrocyte proliferation and re-absorption, we studied a method of cartilage tissue engineering comprising chondrocyte-hydrogel pluronic complex (CPC) and cultured perichondrial cell sheet (cPCs) which entirely cover CPC. For effective cartilage regeneration, cell-sheet engineering technique of high-density culture was used for fabrication of cPCs. Hydrogel pluronic as a biomimetic cell carrier used for stable and maintains the chondrocytes. The human cPCs was cultured as a single layer and entirely covered CPC. The tissue engineered constructs were implanted into the dorsal subcutaneous tissue pocket on nude mice (n = 6). CPC without cPCs were used as a controls (N = 6). Engineered cartilage specimens were harvested at 12 weeks after implantation and evaluated with gross morphology and histological examination. Biological analysis was also performed for glycosaminoglycan (GAG) and type II collagen. Indeed, we performed additional in vivo studies of cartilage regeneration using canine large fullthickness chondrial defect model. The dogs were allocated to the experimental groups as treated chondrocyte sheets with perichondrial cell sheet group (n = 4), and chondrocyte sheets only group (n = 4). The histological and biochemical studies performed 12 weeks later as same manners as nude mouse but additional immunofluorescence study. Grossly, the size of cartilage specimen of cPCs covered group was larger than that of the control. On histological examination, the specimen of cPCs covered group showed typical characteristics of cartilage tissue. The contents of GAG and type II collagen were higher in cPCs covered group than that of the control. These studies demonstrated the potential of such CPC/cPCs constructs to support chondrogenesis in vivo. In conclusion, the method of cartilage tissue engineering using cPCs supposed to be an effective method with higher cartilage tissue gain. We suggest a new method of cartilage tissue engineering using cultured perichondrial cell sheet as a promising strategy for cartilage tissue reconstruction.

• Journal of the Korea Concrete Institute
• /
• v.26 no.2
• /
• pp.151-157
• /
• 2014

Since recently developed Ultra-High-Performance-Concrete (UHPC) provides very high strength, stiffness, and durability, many studies have been made on the application of the UHPC to bridge decks. Due to high strength and stiffness of UHPC bridge deck, the structural contribution of top flange of steel girder composite to UHPC deck would be much lower than that of conventional concrete deck. At this point of view, this study proposes a inverted-T shaped steel girder composite to UHPC deck. This girder requires a new type of shear connector because conventional shear connectors are welded on top flange. This study also proposes three different types of shear connectors, and evaluate their ultimate strength via push-out static test. The first one is a stud shear connector welded directly to the web of the girder in the transverse direction. The second one is a puzzle-strip type shear connector developed by the European Commission, and the last one is the combination of the stud and the puzzle-strip shear connectors. Experimental results showed that the ultimate strength of the transverse stud was 26% larger than that given in the AASHTO LRFD Bridge Design Specifications, but a splitting crack observed in the UHPC deck was so severe that another measure needs to be developed to prevent the splitting crack. The ultimate strength of the puzzle-strip specimen was 40% larger than that evaluated by the equation of European Commission. The specimens combined with stud and puzzle-strip shear connectors provided less strength than arithmetical sum of those. Based on the experimental observations, there appears to be no advantage of combining transverse stud and puzzle-strip shear connectors.

• The Journal of Korean Academy of Prosthodontics
• /
• v.48 no.2
• /
• pp.143-150
• /
• 2010

Purpose: The purpose of this study is to fabricate the new zirconia block (CNU block) and to evaluate fit of core and porcelain veneered zirconia crown. Material and methods: The experimental blocks were fabricated from the commercial ytrria-stabilized zirconia powder (KZ-3YE Type A). The powder was uniaxial pressing and the green bodies were conducted using the Cold Isostatic Pressing. The zirconia blocks were presintered at $1040^{\circ}C$ and the final sintering was performed at $1450^{\circ}C$. The Kavo Everest ZS $blank{(R)}$ (KaVo, Biberach/ $Ri{\beta}$.) was used as a control group. The linear shrinkage of CNU block and Kavo block were compared. Twenty-one cores for porcelain veneered crowns were fabricated with CAD/CAM system ($Everest{(R)}$, Biberach/ $Ri{\beta}$.). Group I; seven cores fabricated from Kavo blocks, Group II; seven cores fabricated from CNU blocks, Group III; seven cores from CNU blocks and porcelain veneering for crowns. All specimens were cemented and sectioned into two planes; diagonal and bucco-lingual. The measurement of the marginal, internal, and occlusal fit was carried out using SEM ($S-4800^{(R)}$) at $30{\times}$. The results were analyzed by one-way ANOVA test. Results: The linear shrinkage of the CNU block and the KaVo block was 19.00% and 20.09%. The marginal gap of cores ($29.67{\pm}6.58{\mu}m$) fabricated from CNU blocks showed significantly smaller than that of the cores of Kavo blocks ($36.84{\pm}7.18{\mu}m$) (P < .05). The internal gaps of the porcelain veneered crowns ($32.23{\pm}6.33{\mu}m$) were larger than those of the other two groups ($37.57{\pm}6.81{\mu}m$ and $38.14{\pm}6.81{\mu}m$). Conclusion: No statistically significant difference was found in between experimental groups and control group. The experimental groups in marginal gap showed significantly smaller than the control group.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.25 no.3
• /
• pp.225-235
• /
• 2009

A common procedure of restoration of endodonticlly treated tooth with fiber-reinforced post is followed by core build-up after post cementation. However, this technique is complex and time-consuming. The aim of this study was to compare fracture strength of premolar, restored with various methods of core fabrications on fiber-reinforced posts and casting metal restoration. Forty five freshly extracted human mandibular premolars were obtained and devided into 5 groups acconding to the type of post and methods of core build-up. In Group A, D.T. $Light-post^{(R)}$ were cemented with $DUO-LINK^{TM}$ and then $LIGHT-CORE^{TM}$ was used for core restoration. In Group B, D.T. $Light-post^{(R)}$ and $DUO-LINK^{TM}$ were used for cementing in the postspace, and $DUO-LINK^{TM}$ was used again for core restoration. In Group C, $Light-post^{(R)}$ bonding and the core build-up were performed simultaneously by using $DUO-LINK^{TM}$. In Group D, $LuxaPost^{(R)}$ was bonded by using $LuxaCore^{(R)}-Dual$. Again, $LuxaCore^{(R)}-Dual$ was used for core restoration. In Group E, $LuxaPost^{(R)}$ bonding and the core build-up were performed simultaneously by using $LuxaCore^{(R)}-Dual$. Axial reduction was formed parallelly as possible and 45 degree bevel was made at buccal occlusal surface. Crowns were fabricated and cemented. Each tooth was embedded in self-curing acrylic resin to the level of 2mm below the CEJ. Specimens were fixed on universal testing machin such that the axis of the tooth was at 45 degree inclination to the horizontal plane, and compressive force was applied at a crosshead speed of 1mm/min until failure occurred. The mean fracture strength was the highest in group A followed by descending order in group B, D, E and C. However, there were no statistically significant differences between groups with regard to the fracture strength. The type of the post or build-up methods of the core does not seem to influence the fracture strength.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.45 no.3
• /
• pp.271-279
• /
• 2018

Previous studies to elucidate the etiology of cyclosporine(Cs)-induced gingival overgrowth in children have not completely excluded all factors that may cause differences among individuals. This study examined the effect of cyclosporine on the metabolism of type 1 collagen(CoL-I) in experimental models that controlled the effects of biological variations on individuals. Five 5-week-old male Sprague-Dawley rats were administered Cs by gastric feeding for 6 weeks. Gingival specimens were harvested from the mandibular posterior area before beginning Cs administration and at 2, 4, and 6 weeks thereafter. Gingival fibroblasts were cultured from all the 20 biopsies collected from the gingiva. Half of the fibroblasts collected prior to the Cs administration were designated as Control. The other half of the fibroblasts were treated with Cs in vitro and called in vitro test group(Tt). The fibroblasts collected 2, 4, and 6 weeks after the Cs administration were called in vivo test groups : T2, T4, T6, respectively. Immunofluorescence microscopy was used to detect CoL-I in all the fibroblasts. CoL-I was analyzed at both the gene and protein expression levels by real-time polymerase chain reaction and western blotting. Changes in CoL-I before and after Cs treatment were evaluated from the gingiva of each rat. There was no significant difference in gene expression of CoL-I in the control and test groups. CoL-I protein expression levels of fibroblasts increased in in vitro Cs treatment for each individual, and also increased in in vivo Cs treatment. In this study, the experimental method that control biological variations that can occur due to differences among individuals was useful. Subsequent studies on other factors besides CoL-I and in-depth studies in humans are needed.

• Korean Journal of Ichthyology
• /
• v.19 no.1
• /
• pp.8-15
• /
• 2007

The morphology of gonad and reproductive cycle of ribbed gunnel (Dictyosoma burgeri) were investigated on the basis of histological observation. The specimens were monthly sampled in the coastal waters of Jeju from November 2001 to February 2003. The ovaries and testis of this species are categorized as cystovarian and lobule type, respectively. The gonadosomatic index (GSI) of female increased in November and maintained high values from December to February. The GSI of male was similar to that of female although it was decreased in February. The reproductive cycle can be grouped into the following successive stage in the ovary: growth (October to November), mature (November to February), spawning (January to February), and degenerating and recovery (March to September). And in the testis, the stage observed were: multiplication (August to November), growth (November to January), mature and spawning (November to February), and degenerating and recovery (January to September). The minimum maturation size of D. burgeri was over 15.0 cm and fecundity ranged from 2,194 to 6,581 eggs. The relationship between the fecundity and fish body was calculated in the fecundity (F) equation as: $F=0.4057TL^{3.1425}$ ($R^2=0.7621$) for total length (TL); $F=149.88BW^{0.9579}$ ($R^2=0.7982$) for body weight (BW), respectively. The fecundity was correlated positively with TL and BW. The histological observations of the gonads suggested that major spawning of this species probably occurs between January to February, when low water temperature ($13{\pm}0.3^{\circ}C$) period.