• The Journal of Korean Academy of Prosthodontics
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• v.48 no.1
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• pp.8-15
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• 2010

Purpose: The purpose of this study was to evaluate the effect of various methods of dentin bonding agent application and air abrasion pretreatment on microtensile bond strength between dentin and resin, using a self-etching adhesive system. Material and methods: Thirty freshly extracted human molars were obtained and divided into 6 groups of 5 teeth. A 2-step self etching adhesive system (Clearfil SE Bond) was used for all groups. The control specimens were prepared using a direct immediate bonding technique. The delayed dentin sealing specimens were prepared using an indirect approach without dentin prebonding. The immediate dentin sealing specimens were prepared using dentin prebonding immediately following preparation. Immediate dentin sealing teeth and delayed dentin sealing teeth had provisional restorations using Fermit for two weeks. Then all specimens of each group were divided into two groups of three, depending on air abrasion pretreatment. Composite "crowns" were incrementally built on and specimens were stored in water for 24 hours. All teeth were prepared for a microtensile bond strength test. Bond strength data were analyzed with a one-way ANOVA test, and post hoc comparison was done using the Scheffe's test. Results: The mean microtensile bond strengths of all groups were not statistically different from each other. Conclusion: When preparing teeth for indirect restorations, IDS and DDS with Clearfil SE bond, have no difference on the microtensile bond strength between dentin and resin. Air abrasion pretreatment did not affect the microtensile bond strength when using IDS and DDS with Clearfil SE bond.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4668-4678
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• 2015

This study was conducted to determine the correlation between breakfast consumption and health-related quality of life in elderly adults. It analyzed the data from the National Health and Nutrition Examination Survey from 2010 to 2012, using a sample of 4,035 people aged 65 or above. Analysis followed the SAS SURVEY procedure, considering the complex sample design. A t-test, a chi-square test, and logistic regression analysis were performed using SAS version 9.3. The rate of skipping breakfast by elderly adults was 4.7%, and it was higher in women and elderly adults living alone. It also significantly differed by drinking status and BMI. Elderly adults consuming breakfast had slightly higher scores on the health-related quality of life measure than those who did not (0.85 vs 0.81). Results revealed that health-related quality of life increased with meal frequency, and that elderly adults who ate breakfast tended to score better on the pain/discomfort and anxiety/depression domains of the health-related quality of life measure. It was found that breakfast consumption associated with health-related quality of life in elderly adults. Accordingly, it is necessary to increase awareness among elderly adults regarding the importance of breakfast, and to improve their health-related quality of life by developing and implementing interventions to improve dietary habits.

• Applied Microscopy
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• v.30 no.3
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• pp.285-293
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• 2000

The present study has been carried out to investigate the effect of fluoride toxicity on the morphology as well as inorganic chemical constituents of rat teeth. Rats were administered sodium fluoride at dose of 0 ppm, 100 ppm, 200 ppm and 300 ppm at the beginning of pregnancy. Animals were perfused intravascularly with glutaraldehyde and the incisors were removed. Changes in the protein composition of the secretory and maturation enamel were investigated using polyacrylamide gel electrophoresis (SDS PAGE). And the enamel surface of incisors was examined under scanning electron microscope (SEM). Changes of protein quantities were found significantly in high levels fluoride administration for experimental groups compared with control. The SDS PAGE analysis demonstrated as follows In control group, secretory phase enamel protein, amelogenins, was detected more quantities than experimental group. The enamelin, presence in maturation phase enamel , showed more quantifies than control enamel with an increasing fluoride concentration in the drinking water. Also, the scanning electron micrographic data showed hypoplastic, tough, uneven, pitted and cracked enamel surfaces covered with granular deposits as a result of excessive intake of fluoride. From these results we conclude that high dose of fluoride administration leads to severe structural alterations on the enamel surface and these structural changes could be through defective mineralization.

• The Korean Journal of Mycology
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• v.36 no.1
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• pp.22-25
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• 2008

Pleurotus eryngii is by far the best tasting oyster mushroom, well deserving of the title, the King Oyster. Popular in Europe, this stout, thickly fleshed mushroom, is one of the largest species in the genus. The effects of addition of crab shell to sawdust substrate for the growth of P. eryngii were investigated. Dried crab shell used in this study contained 55.2% C, 3.74% N, 5.57% $P_2O_5$, 6.44% Ca, and pH 6.9. The addition of 1% crab shell (v/v) increased the yield of the mushroom fruit-body by 34% comparing control (sawdust 80, rice bran 20; v/v), 0.03% CaO content of 1% crab shell treatment was higher than 0.01% CaO of control and period of primordia formation was similar regardless of the treatments.

• The KIPS Transactions:PartD
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• v.10D no.4
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• pp.591-602
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• 2003

Delay and discontinuance phenomenon of service are cause by sudden increase of the network communication amount and the quantity consumed of resources when Internet users are driven excessively to a conventional single large database sewer. To solve these problems, spatial database cluster consisted of several single nodes on high-speed network to offer high-performance is risen. But, research about spatial join operation that can reduce the performance of whole system in case process at single node is not achieved. So, in this paper, we propose efficient parallel spatial join processing method in a spatial database cluster system that uses data partitions and replications method that considers the characteristics of space data. Since proposed method does not need the creation step and the assignment step of tasks, and does not occur additional message transmission between cluster nodes that appear in existent parallel spatial join method, it shows performance improvement of 23% than the conventional parallel R-tree spatial join for a shared-nothing architecture about expensive spatial join queries. Also, It can minimize the response time to user because it removes redundant refinement operation at each cluster node.

• Journal of the Korea Concrete Institute
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• v.21 no.6
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• pp.689-696
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• 2009

In this study, electro-deposition method was applied to heal cracks in various blended concrete. The performance of the method was indirectly monitored by measuring impressed voltage, electrolyte, galvanic current monitoring, linear polarization resistance, and directly by image analysis of the cracks. The indirect and direct monitoring values are compared to develop guidelines for relating the indirect measures to actual crack healing. As a result, It was found that impressed voltage was convergence to 2.9V after 20000 minutes. From the galvanic current test results of artificial crack healing, the corrosion resistance showed that the order of 0.4 $>$ 0.6 $>$ 0.5 water to cement ratio. Furthermore, in view of binder, the corrosion resistance order was calculated OPC $>$ 60%GGBS $>$ 10%SF $>$ 30%PFA. Finally, It was found that 76.47% of healed crack surface calculated from the artificial crack healing technique using electrochemical deposition method.

• Journal of Korea Spatial Information System Society
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• v.8 no.2 s.17
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• pp.53-73
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• 2006

Recently, the need for Location-Based Services (LBS) has increased due to the development of mobile devices, such as PDAs, cellular phones and GPS. As a moving object database that stores and manages the positions of moving objects is the core technology of LBS, the scheme for maintaining the main memory DBMS to the server is necessary to store and process frequent reported positions of moving objects efficiently. However, previous works on a moving object database have studied mostly a disk based moving object index that is not guaranteed to work efficiently in the main memory DBMS because these indexes did not consider characteristics of the main memory. It is necessary to study the main memory index scheme for a moving object database. In this paper, we propose the main memory index scheme based on the R-tree for storing and processing positions of moving objects efficiently in the main memory DBMS. The proposed index scheme, which uses a growing node structure, prevents the splitting cost from increasing by delaying the node splitting when a node overflows. The proposed scheme also improves the search performance by using a MergeAndSplit policy for reducing overlaps between nodes and a LargeDomainNodeSplit policy for reducing a ratio of a domain size occupied by node's MBRs. Our experiments show that the proposed index scheme outperforms the existing index scheme on the maximum 30% for range queries.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.4
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• pp.601-606
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• 2009

Amelogenesis Imperfecta (AI) is a genetic disorder which retards the development of enamel and it can be classified into three types: hypoplastic, hypomaturation, hypocalcified type. This can occur both in deciduous and permanent dentition. A 8 year 8 month old patient with a chief complaints of delayed eruption on upper anteriors, calculus deposit on lower anteriors and anterior openbite visited the clinic. Anteriors had thin layer of enamel and were very narrow. Especially lower anteriors had rough surface and were in bad shape. Teeth were very hypersensitive to thermal changes. Upper and lower first molars showed severe attrition on the occlusal surface. Radiographs also verified hypoplastic enamel in the whole dentition including the teeth in the tooth bud. The patient was diagnosed as hypoplastic AI, and is being treated at the pediathc and prosthodontic department of the Kyunghee dental university hospital. To improve the function, esthetics, hypersensitivity of the AI patients, restorations on the posteriors and the anteriors with oral hygiene instruction are necessary, Constant follow-up check is needed until full growth and after full growth, cooperative care with the other department is needed.

• Clinical and Experimental Pediatrics
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• v.51 no.12
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• pp.1342-1345
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• 2008

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare white matter disorder, first described in the early 1990s. The brain in patients with MLC appears swollen on MRI, with diffuse white matter abnormalities; in addition, there is an invariable presence of subcortical cysts, primarily in the anterior temporal region sparing the deep white matter, basal ganglia, thalami, and cerebellum. Patients with MLC present with macrocephaly and neurological abnormalities such as motor deterioration, ataxia, spasticity, and cognitive deficits. We report a twenty-month-old boy who presented with seizures and macrocephaly, delay in development, and abnormal brain MRI findings compatible with the diagnosis of MLC. The brain MRI revealed bilateral hypersignal intense subcortical white matter regions in the frontal, temporal, and parietal lobes on T2-weighted images, which were not yet associated with cystic changes. During follow-up, the frequency of seizures decreased after anticonvulsant medication was started, but the head circumference remained above the 97th percentile, and the patient continued to have developmental delay.

• Applied Microscopy
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• v.40 no.4
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• pp.245-251
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• 2010

In this study, we applied 15% glycolic acid peeling agent and 30% glycolic acid peeling agent to the dorsal skin of mice and analyzed the oil content, moisture content, and pH value of the skin before and after test using cutometer. Ultrastructure for changes in the epidermis of mice were observed under a dermoscope and a scanning electron microscope before and after test. When using 15% glycolic acid peeling agent, the changes of moisture content was measured 74.67 AU for the normal control group and 70.21 AU for the experimental group, the oil content was 13.49 mg/$cm^2$ for the normal control group before test and 8.25 mg/$cm^2$ after test, and the pH value was 6.70 and 5.36 before and after test, respectively. When using 30% glycolic acid peeling agent, the moisture content was measured 74.46 AU for the normal control group before test and 53.50 AU for the experimental group after test, the oil content was 13.82mg/$cm^2$ and 5.70 mg/$cm^2$ before and after test, and the pH value was 6.45 and 4.58 before and after test, respectively. As such, it was found that the changes of moisture and oil content on the skin rely on the concentration of peeling agent and the degree of exfoliation of keratin. The surface of stratum corneum of mice with application of 15% glycolic acid peeling agent was relatively smooth and the exposed cellular surface of keratinocyte had some wrinkles. The surface of stratum corneum of mice with application of 30% glycolic acid peeling agent was smooth. No wrinkles were observed under high-resolution scanning electron microscope.