• Journal of Korean Foot and Ankle Society
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• v.10 no.2
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• pp.117-124
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• 2006

Purpose: This study was aimed at elucidating the pathogenesis of talar osteochondral lesion by analyzing the histopathological findings. Materials and Methods: Twenty specimens from 20 patients who underwent surgical treatment for talus osteochondral lesions were studied. Preoperative MRI images including T1, T2, and stir images were taken and cases were classified according to modification of the Anderson's classification. There were 5 cases of MRI group 1, 6 cases of group 2, 7 cases of group 3 and 2 cases of group 4. A full thickness osteochondral plug including the osteochondral lesion of the talus was harvested from each patient and reviewed histopathologic changes of osteochondral fragment using H-E staining. Mean diameter of specimens was 8.5 mm and mean depth was 10.3 mm. Pathologic changes of articular cartilage and subchondral bone were observed. Subchondral bone was divided into superficial, middle and deep zones according to depth. Cartilage formation, trabecular thickening and marrow fibrosis were observed in each zone. Results: There were detachment of the joint cartilage at the tidemark in 16 cases of 20 cases and the separated cartilages were almost necrotic on the histopathologic findings. Cartilage formation within subchondral bone was discovered beneath the tidemark in 12 cases. Trabeculae were increased and thickened in 17 cases. These pathologic changes were similar to fracture healing process and these findings were more conspicuous near the tidemark and showed transition to normal bone marrow tissue with depth. No correlation between the pathological progression and MRI stages was found. A large cyst shown on MRI's was microscopically turned out to be multiple micro-cysts accompanied by fibrovascular structure and newly formed cartilage tissue. Conclusion: The histopathologic findings of osteochondral lesions are detachment of overlying cartilage at the tidemark and subsequent changes of subchondral bone. Subchondral bone changes are summarized as cartilage formation, marrow fibrosis and trabecular thickening that mean healing process following repeated micro fractures of trabecular. These osteochondral lesions should have differed from osteochondral fractures.

• Journal of Educational Research in Mathematics
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• v.17 no.2
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• pp.163-177
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• 2007

Studies on mathematically gifted students have been conducted following Krutetskii. There still exists a necessity for a more detailed research on how these students' mathematical competence is actually displayed during the problem solving process. In this study, it was attempted to analyse the algebraic thinking process in the problem solving a peg puzzle in which 4 mathematically gifted students, who belong to the upper 0.01% group in their grade of elementary school in Korea. They solved and generalized the straight line peg puzzle. Mathematically gifted elementary school students had the tendency to find a general structure using generic examples rather than find inductive rules. They did not have difficulty in expressing their thoughts in letter expressions and in expressing their answers in written language; and though they could estimate general patterns while performing generalization of two factors, it was revealed that not all of them can solve the general formula of two factors. In addition, in the process of discovering a general pattern, it was confirmed that they prefer using diagrams to manipulating concrete objects or using tables. But as to whether or not they verify their generalization results using generalized concrete cases, individual difference was found. From this fact it was confirmed that repeated experiments, on the relationship between a child's generalization ability and his/her behavioral pattern that verifies his/her generalization result through application to a concrete case, are necessary.

• International Journal of Highway Engineering
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• v.8 no.4 s.30
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• pp.115-124
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• 2006

The objectives of this paper are to develop the structural condition evaluation technique using Falling Weight Deflectometer deflections and propose the structural condition criteria for asphalt pavements. To figure out correlation between surface deflections and critical pavement responses, the synthetic database has been established using the finite element pavement structural analysis program. A regression approach was adopted to develop the pavement response model that can be used to compute the stresses and strains within pavement structure using the FWD deflections. Based on the pavement response model, the procedure for assessing the structural condition of pavement layers was proposed in this study. To validate the condition evaluation procedure for asphalt pavements, the FWD test, dynamic cone penetrometer test, and repeated triaxial compression test were conducted on 11 sections of national highway and 8 sections of local road. Test results indicate that the tensile strain at the bottom of AC layer and AC elastic modulus were good indicators for estimating the stiffness characteristics of AC layer. For subbase layer, the BDI value and compressive strain on top of the subbase layer were appropriate to predict the structural capacity of subbase layer. The BCI value and compressive strain on top of the subgrade were found to be good indicators for evaluating the structural condition of the subgrade. The evaluation criteria for structural condition in asphalt pavements was also proposed in this paper.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.105-112
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• 2013

PURPOSES : Compared to the criteria from advanced countries, Korea has conservative criteria for the buried depth of pipeline (about 30~70cm deeper) causing the waste of cost and time. Therefore, this research investigated the effect of various buried depths of pipeline on pavement performance in order to modify the criteria to be safe but economical. In addition, a recycled aggregate which is effective in economical and environmental aspect was evaluated to be used as a refilling material. METHODS : In this study, total 10 pilot sections which are composed with various combinations of pavement structure, buried depth of pipeline, and refilling material were constructed and the telecom cable was utilized as a buried pipeline. During construction, LFWD (Light Falling Weight Deflectometer) tests were conducted on each layer to measure the structural capacity of underlying layers. After the construction is completed, FWD (Falling Weight Deflectometer) tests and moving load tests were performed on top of the asphalt pavement surface. RESULTS : It was found from the LFWD and FWD test results that as the buried depth decrease, the deflections in subbase and surface layer were increased by 30% and 5~10%, respectively, but the deflection in base layer remained the same. In the moving load test, the longitudinal maximum strain was increased by 30% for 120mm of buried depth case and 5% for 100mm of buried depth case. Regarding the effect of refilling material, it was observed that the deflections in subbase and surface layer were 10% lager in recycled aggregate compared to the sand material. CONCLUSIONS : Based on the testing results, it was found that the change in buried depth and refiliing material would not significantly affect the pavement performance. However, it is noted that the final conclusion should be made based on an intensive structural analysis for the pavement under realistic conditions (i.e., repeated loading and environmental loading) along with the field test results.

• Korean Journal of Animal Reproduction
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• v.17 no.4
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• pp.339-346
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• 1994

An understanding of the structure and function of mammalian spermatozoa requires the iso-lation of these components. In this study, frozen-thawed bovine spermatozoa were treated by physical treatments (vortexing, 26 gauge needle, strained 26 gauge needles and freezing-thawing) or chemical treatments (trypsin, dithiothreitol, sodium dodecylsulfate and $\beta$-mercaptoethanoJ) to yield free heads and tails. The most effective treatment was repeated pumping of sperm suspension through a strained 26 gauge needle conneted to a syringe. Spermatozoa by this treatment were mainly broken at the junction of the head and the tail, resulting in 90-100% yields. Also, sperm head surface did not modify during strained 26 gauge needle treatment when either spermatozoa or sperm heads were incubated in 250${\mu}\textrm{g}$/ml of FITC-UEA 1 for 1 h at room temperature to detect the modification of sperm surface components. Other physical treatments were less efficient for the breakdown of spermatozoa. The effects of chemical treatments on bovine spermatozoa are not noticeable. Dissected sperm heads and tails should be fractional leading to nearly pure components by sucrose gradient centrifugation at 1,000 rpm for 15 min. The result suggest that the established method may be useful for the biochemical study of spermatozoal components, and the understanding of oocyte activation mechanism either by spermatozoal components during fertilization or microinjection of isolated components.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.656-669
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• 1998

Hydrogen peroxide at high concentration during walking bleaching may cause damage to the tooth structure and to the surrounding periodontal tissues and may develop external root resorption. Clinically, It is so important to find a method of prevention or minimization of these complications. The efficacy of various chamber-irrigating agents to eliminate residual hydrogen peroxide after walking bleaching was examined and compared with water rinse in this study. Extracted human 46 premolars without any cementoenamel junction defects were treated endodontically and based with IRM to 1 mm below CEJ and totally bleached 3 times for each tooth with 30% hydrogen peroxide and sodium perborate. Upon completion of the 3rd walking bleaching procedure, the cervical portion and pulp chamber of each group of teeth were irrigated with catalase, 70% ethylalcohol, acetone, and distilled water. And then, a radicular hydrogen peroxide penetration was measured with spectrophotometer immediately after each bleaching and following treatment with each chamber-irrigating agents, and the significance of their eliminating efficacy of residual hydrogen peroxide was analyzed by Kruskal-Wallis test. The results were obtained as follows. 1. Cervical root penetration of hydrogen peroxide was increased as the bleaching procedure was repeated(P<.01). 2. The most effective irrigant that removed residual hydrogen peroxide was the catalase, and the least effective one was water rinsing (P<.01).; there was no significant difference between the acetone and ethanol group. 3. The Irrigation with antioxidant enzyme or water-displacement solutions can eliminate residual oxygen radicals from the pulp chamber effectively after walking bleaching. So, these agents can reduce adverse effects such as cervical external resorption and periapical inflammation and prevent residual $O_2$ from impeding composite resin polymerization, thus increase the bonding strength of composite resin. This, in turn reduces microleakage and discoloration of the esthetic restoration, extending its service-life.

• Journal of the Korean GEO-environmental Society
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• v.17 no.12
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• pp.35-43
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• 2016

With the development of construction technology, constructions of dam and levee (dike) as well as the environmental problems are becoming issues. Recently, many countries have tried to develop and used CSG (Cemented Sand and Gravel), which needs fewer requirements than others in aggregates, constructability and ground condition during the dam construction. Mixing up with small amount of cement, CSG is able to increase the strength and proceed accelerated construction without artificial gradation adjustment of riverbed aggregate and crushed rock on construction site. Thus, CSG can minimize environmental damage resulted from quarries mining and reduce cost of construction. Unlike heat of hydration condition that regular concrete usually met, CSG exposes to repeated dry-wet and freezing and thawing environment. Thus, consider the importance of structure of dam or levee, intensive study on the durability of CSG is needed. In this study, freezing and thawing experiment was carried out to evaluate the durability of CSG. In results, the durability factor of CSG is 30~40 or >40 when the amount of cement is $0.4{\sim}0.6kN/m^3$ or $0.8{\sim}1.0kN/m^3$, respectively. The unconfined compressive strength is reduced to 30~50% or 40~70% when the amount of cement is $0.4{\sim}0.6kN/m^3$ or $0.8{\sim}1.0kN/m^3$, respectively. Taken together, the strength and durability of CSG is reliable when the amount of cement is over $0.8kN/m^3$.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.39-45
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• 2008

A levitation rail is placed on the top of track structure to operate Maglev vehicles and a part of track that link up with a sleeper is applied repeated load in Maglev vehicles operation. This paper aimed to verify validity of design for levitation rail, through the fatigue analysis about load which is applied to levitation rail in Maglev vehicles operation and impact load occurring in an emergency landing. Load conditions applied design load(23kN/m) in normal operation and skid drop load(24kN/m) in vehicle drop. And boundary conditions are consider bolt fixing and welding. Through static analysis, weak point and maximum stress of levitation rail could be obtained. S-N(stress-life) method was used in oder to predict fatigue life, and Goodman relationship was applied to consider a effect of mean stress. Also damage was calculated by using Miner's. As a result of fatigue analysis, levitation rail had a fatigue life which was more than requirement ($10^6$cycle) in all analysis conditions. Assumption that $10^8{\sim}10^9$cycles is infinite life, all analysis conditions had infinite life except a case under drop load and bolt fixing($1.21{\times}10^6$).

• Journal of Life Science
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• v.24 no.3
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• pp.234-241
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• 2014

To identify and isolate anticancer active compounds from Solanum nigrum, S. nigrum was extracted with MeOH and then fractionated with various organic solvents ($CH_2Cl_2$, EtOAc, n-BuOH, and $H_2O$). The cytotoxic effects of the MeOH extracts from S. nigrum and its organic solvent-soluble fractions were also tested in HT29 cells. All the MeOH extracts of S. nigrum and its organic-solvent extracts induced cytotoxicity in the HT29 cells. Among the extracts, $H_2O$ was the most effective. The $H_2O$ extract was purified further by repeated silica gel, Sephadex LH-20, Diaion HP- 20, and RP-18 column chromatography. An active anticancer compound, Des-N-26-methylene-dihydrotomatidine, was isolated with a molecular weight of 416 and a molecular formula of $C_{28}H_{48}O_2$. Analysis of the cytotoxic effects of Des-N-26-methylene-dihydrotomatidine on the HT29 cells compared to those of tomatine and tomatidine are similar in its structure, is higher than tomatidine above the 40 ${\mu}g/ml$ concentration, but lower than tomatine. This is the first study to describe the anticancer activity of Des-N-26-methylene-dihydrotomatidin, isolated from S. nigrum. Des-N-26- methylene-dihydrotomatidine seems to have potential as a natural bioactive compound.

• Journal of muscle and joint health
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• v.7 no.2
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• pp.281-293
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• 2000

This study was conducted to identify the relationships among self-care agency, family support, qualify of life in patients with rheumatoid arthritis. The subjects were 120 rheumatoid arthritis patients who attended RA O.P.D. at a university hospital, located in Daegu city, from 10th of May in 1998 to 30th of July in 1998. Three structure questionnaires were administered for explore three main research variables; 소향숙's self-care agency scale, 강현숙's family support scale, and 김종임's quality of life scale of RA patien. Data analysis was conducted with SPSS program including percentage, mean, standard deviation, mean score, Pearson Correlation Coefficient, multiple regression, and Cronbach's Alpha. Results are summarized as follows; 1. The mean of RA patient's self-care agency was 136.62, the mean of family support 37.38, and the mean of qualify of life 134.41. 2. Subject's self-care agency was positively correlated with family support(r=.2446) and with quality of life(r=.4341). Subject's family support was positively correlated with quality of life(r=.2630). 3. Stepwise multiple regression was used to determine the predictors of subject's quality of life. Significant predictors for subject's quality of life were self-care agency(t=4.873 p=0.0000), family support(t=4.480 p=0.0000) and the severity of arthralgia(t=-3.838, p=0.0002). The number of joints involved and the periods of illness did not show significant contribution to subject's quality of life. Self-care agency, family support, and family support explained 40. 39% of the variance in RA patient's quality of life. Given this results, it is suggested that a repeated study to measure RA patient's self-care practice in their own life may be needed to develope and validate an optimum level of nursing intervention for RA patient with which family support will be encouraged and patient's self-care agency will be facilitated.