• The korean journal of orthodontics
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• v.28 no.2 s.67
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• pp.329-341
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• 1998

Sterilization has received much attention in orthodontic practices over the past several years. The present study was undertaken to investigate the effects of sterilization on the physical properties of orthodontic pliers-AEZ, Unitek, and Dentronix ligature cutters. This study was designed to examine the tips of ligature cutters before and after 200 and 400 sterilization cycles using the Bowmar RHT-1000, the Dentronix DDS-5000, and the Eschmann SES-2000. The tip surface and the fracture surface were observed with a scanning electron microscope. The microstructure was observed with an optical microscope. The hardness test was carried out with the mic개-Vickers hardness tester and the Rockwell C Scale hardness tester. The chemical composition was analyzed by energy dispersive X-ray spectrometer. The results of this study were as follows : 1. The number and the size of corrosion products on the tip surface and the proportion of cleavage planes in fractured specimen increased, but the hardness of the tip decreased in proportion to sterilization cycles. From these observations, it was considered that mechanical properities decreased in proportion to sterilization cycles. 2. The number and the size of chromium carbides increased in proportion to sterilization cycles. Coarse microstructure decreased mechanical properities. 3. The AEZ and Unitek ligature cutters were Fe-Cr stainless steels, but the Dentronix ligature cutter was Co-Cr alloy. There were many differences among manufactures, but the chemical composition was .not changed after sterilization cycles. 4. The tip edge of ligature cutter used in a clinic revealed microcracks with the SEM observation. Clinical experience confirmed that ligature cutters were gradually degraded by sterilization.

• The korean journal of orthodontics
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• v.32 no.2 s.91
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• pp.117-127
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• 2002

The purpose of this study was to compare the arch width of the hyperdivergent group with that of the neutral group in Class III malocclusion based on the vertical patterns and to compare the arch width of Class III neutral group With that of normal occlusion group based on sagittal patterns. The subjects consisted of 118 pairs of studty casts, divided into three groups , 37 Class III hyperdivergent group(18 males and 19 females, SN-Mn plane angle>39.5$^{\circ}$), 40 Class III neutral group(20 males and 20 females, SN-Mn plane angle : 32 ${\pm}$ 2.5$^{\circ}$) and 41 Class I normal occlusion group(20 males and 21 females). The intercanine, interpremolar, and intermolar width of the maxillary and mandibular study casts were measured, then the ratios of dental width to basal width and mandibular width to maxillary width were obtained. Basal arch width and dental arch width were measured to obtain the pure basal arch relation in transverse plane as ruled out the transverse dental compensation. The results were as follows 1. There were no significant differences in any ratios between Class III hyperdivergent group and Class III neutral group as different vertical pattern. 2. As the ratios of dental arch width to basal arch width between normal occlusion group and Class III neutral group were compared, the maxillary teeth flared buccally to the basal bone, and the mandibular teeth tilted lingually to the basal bone in Class III neutral group. 3. The ratios of mandibular arch width to maxillary arch width in basal arch level were significantly different in all regions. Maxillary basal arch width of Class III neutral group was narrower than that of normal occlusion group. 4. The ratios of mandibular arch width to maxillary arch width in teeth level were not significantly different between normal occlusion group and Class III neutral group. In spite of discrepancies of maxillary and mandibular basal arch width, the dental arch width of Class III malocclusion group compensated very well. At the presurgical orthodontic treatment in clinic, it would not be desirable to decompensate for compensated dental arch width too much, for obtaining an appropriate arch compatibility and good results for orthognathic surgery.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9B
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• pp.610-618
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• 2005

As developed Internet and Computer Capability, Many Users take the many information through the network. So requirement of User that use to network was rapidly increased and become various. But it spend much time to accept user requirement on current network, so studied such as Active network for solved it. This Active node on Active network have the capability that stored and processed execution code aside from capability of forwarding packet on current network. So required execution code for executed packet arrived in active node, if execution code should not be in active node, have to take by request previous Action node and Code Server to it. But if this execution code take from previous active node and Code Server, bring to time delay by transport execution code and increased traffic of network and execution time. So, As used execution code stored in cache on active node, it need to increase execution time and decreased number of request. So, our paper suggest ANC caching technique that able to decrease number of execution code request and time of execution code by efficiently store execution code to active node. ANC caching technique may decrease the network traffic and execution time of code, to decrease request of execution code from previous active node.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.421-430
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• 2004

The purpose of this study was to measure and compare the amount of unreacted TEGDMA from pit and fissure sealants cured with three different light sources; conventional halogen light curing unit, plasma arc light curing unit and argon laser. The specimens were eluted in distilled water for different time intervals. The time-related release of TEGDMA were analyzed by reverse-phase high performance liquid chromatography(HPLC). The result of present study can be summarized as follows: 1. The time-related release of TEGDMA decreased with increasing curing time in conventional halogen light, however, that not statistically significant difference(p>0.05). 2. The elution from the specimens cured for 6 and 9 seconds with plasma arc light was similar results corresponding with the time-related TEGBMA release, and was significantly lower than that cured for 3 seconds(p<0.05). 3. The elution of TEGDMA from the specimens cured with argon laser was significantly higher than that cured with halogen and plasma arc light(p<0.05). 4. The elution of TEGDMA from under recommended time of three different light sources were showed to be no statistically significant difference(p>0.05). 5. In time-related release of TEGDMA from recommended time of each light sources, the results correspond to 40 seconds of halogen light and 6 seconds of plasma arc light were similar(p>0.05). 6. The elution of TEGDMA, from over recommended time of three different light sources were showed to be no statistically significant difference(p>0.05). In this study, I suggest that curing time of plasma arc light is 6 and/or 9 seconds in the field of clinical pediatric dentistry claiming its effectiveness in optimal polymerization and reduced chair time.

• Journal of Bio-Environment Control
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• v.23 no.1
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• pp.1-10
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• 2014

This study analyzed the efficiency and uniformity by measuring the temperature change depending on the position in the chamber with the use of QRD (quadratic residue diffusor) microwave capable of inducing even sterilization by changing wavelength phase difference and enhancing the effect on low power. The results are summarized as follows: When irradiating 7 kW of QRD microwave, the highest efficiency was obtained at 35 cm height and in the center of the chamber. When irradiating 5 kW of QRD microwave, high efficiency was obtained on the sides of the chamber. When irradiating 3 kW of QRD microwave to Magnetrons 1, 2 and 3, the temperature uniformity according to the position of the bars was similar in the position of Bar 1 and 2. When irradiating 3 kW of QRD microwave to Magnetrons 3, 4 and 5, the temperature increased by approximately 10 to 20% in Bar 3. When irradiating 5, 7 and 9 kW of magnetron, the average temperature during the irradiation time increased in a similar form independently of the position of the bars. On the other hand, the efficiency of the chamber's proper internal volume was not necessarily proportional to the irradiation dose. When irradiating 3 kW of magnetron for 60 120 and 180 seconds, the temperature increased by approximately 5 to 10 at the edge of the chamber according to the irradiation position of magnetron. The temperature distribution for each position in the horizontal plane was relatively uniform, and the temperature had a tendency to slightly increase at the edge. When irradiating 5, 7 and 9 kW of magnetron, the temperature relatively evenly increased independently of the position of the bars. It was thought necessary to increase the irradiation dose by approximately 10 to 20% by considering the difference in temperature rise according to the position of magnetron.

• Journal of the Korean Society of Radiology
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• v.6 no.5
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• pp.421-426
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• 2012

The purpose of this study was to investigate the knowledge of dental hygiene students of the quality assurance of dental radiation such quality assurance and related educational experiences in an effort to accelerate the preparation of a curriculum for systematic quality-assurance. The subjects in this study were 453 dental hygiene students who participated in dental radiography courses. Varied statistical analyses such as frequency analyses, reliability, chi-square, and independent samples t-tests were conducted on the data collected, using SPSS 12.0. Scheffe test was also used after one-way ANOVA as post-hoc tests. Results showed that (a) the students' acknowledge level of Radiographic Quality Assurance was $7.71{\pm}1.7$ out of 12 on average. The more theory and practical classes students took, the higher points they got (p<0.001); (b) Most of the students experienced 1-3 lessons out of 13 in practical training and 26.3% of students did not take any practical lesson. ;(c)Students who did not take any practical training got 7.20 points out of 13, students who took 1-3 lessons got 7.84 points out of 13, students who took 4-5 lessons got 7.87 points out of 13, and students who took more than 6 lessons got 8.14 points out of 13 on average. The more practical classes they took the higher acknowledge level they were. Therefore it needs to provide adequate practical lessons to them.

• Pediatric Infection and Vaccine
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• v.17 no.2
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• pp.148-155
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• 2010

Purpose : The purpose of this study was to investigate clinical features and culture-positive rates according to the involved lung in adolescent pulmonary tuberculosis (TB). Methods : We retrospectively reviewed the medical records of adolescents who ranged in age from 10 to 20 years and who had been hospitalized with a diagnosis of TB at Kwangju Christian Hospital from 2000 to 2008. Results : Sixty-six patients were identified with pulmonary TB: median age 16.82 years; 48.5% males. Among them, 90.9% of patients were between 15 and 20 years of age. Most patients presented with multiple symptoms, and the most common included cough (74.2%), sputum (60.6%), fever (39.5%), and night sweating (18.2%). Sputum samples were smear-positive in 28 (42.4%), culture-positive in 40 (60.6%), and PCR-positive in 46 (69.7%). The most common radiological patterns included cavitation in 18 (27.3%), pleural effusion in 18 (27.3%), lymphadenopathy in 10 (15.2%), and tuberculoma in 5 (7.6%). The prevalence of smear, culture, and PCR positive rates increased as the number of involved lobes increased (P<0.05, P<0.01, P<0.05). The median treatment duration was 7 months. Twelve patients (18.2%) had lower lung field TB (Group A) and forty-four patients (66.7%) had other areas involving TB, except for Group A (Group B), and ten patients (15.1%) had only TB pleurisy (Group C). The difference of clinical characteristics and culture rates between group A and group B was not significant. Conclusion : Pulmonary TB toward late adolescence is increasing. We need to pay more attention to lower lung field TB, which is difficult to detect with specific radiographic findings.

• Korean Journal of Poultry Science
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• v.32 no.2
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• pp.89-96
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• 2005

This studies were conducted to investigated the feeding effects of extruded broiler manure(BMERF) mixture and swine manure(SFERF) mixture on laying performance and egg qualify of laying hens. As a experimental feed, broiler manure, corn and tapioca were mixed in 50, 30 and $20\%$ to use for treated extrusion feed(BMERF, Exp. 1) and food waste(FW), swine manure and com were also mixed in 40, 40 and $20\%$ to use it(SFERF, Exp. 2) and implemented during 12 weeks, four replication and 30 chick of each treatment. The nutritional ingredients(protein, energy and calcium contents) of food waste, broiler manure and swine manure had been significantly improved(p<0.05) when handling extrusion. In the Exp. 1, the feed intake was much higher BMERF $40\%$ and BMERF $20\%$ than control and BMERF $10\%(p<0.05)$, the egg production of control, BMERF $10\%$ and BMERF $20\%$ were not significantly difference(p>0.05), but BMERF $40\%$ was significantly lower(p<0.05). The feed efficiency of control and BMERF $10\%$ were not significantly difference(p>0.05), but BMERF $20\%$ and BMERF $40\%$ were significantly lower(p<0.05). York color, White height and Haugh unit did not affected by BMERF additive. In the Exp. 2, the feed intake of control, FW $20\%$, SFERF $10\%$ and SFERF $20\%$ were not significantly difference(p<0.05), but FW $40\%$ and SFERF $40\%$ were significantly higher(p<0.05). The egg production of SFERF $10\%$ and SFERF $20\%$ were not significantly difference(p>0.05) with control, but FW $20\%$, FW $40\%$ and SFERF $40\%$ were significantly lower(p<0.05). The feed efficiency was similar tendency to the egg production, however, the egg weight, york color, white height and haugh unit were not significantly difference among each treatments(p>0.05).

• Korean Journal of Poultry Science
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• v.33 no.1
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• pp.57-63
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• 2006

This study was conducted to investigate the effect of ventilating system of environmental controlled broiler house on broiler production. Three hundred eighty four broiler chicks (Hubbard, mean live weight of $44.5{\pm}2.0g/bird$) were reared for 2 wk. The results of the present study were summarized as follows : 1. Ammonia gas production was lower in the second and the third floors of cages compared with first floor of cages 13.5 and 13.5 vs 14.6 ppm, respectively). The observations of ammonia production in the morning and afternoon were similar. The production of carbon dioxide was not different between morning and afternoon, but it was tended to decrease in the forth floor of cages due to a fresh air 2. A wind velocity in the enclosed house was similar across lower, middle and upper section (0.57m/sec, 0.22m/sec and 0.04msec, respectively). In order to maintain an optimal air flow velocity in the cages, the duct entrance was punched, and then the air flow was full-round in the overall space in the cage. 3. Daily liveweight gain, feed intakes, and feed efficiency were not significant differences among treatments during whole experimental period (P>0.05). Therefore, the present results showed that temperature, moisture and atmosphere controlling were desirable, and air flew evenly in the cage.

• Korean Journal of Poultry Science
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• v.33 no.2
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• pp.151-158
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• 2006

In order to study the effects of supplementary $Safmannan^(R)$(Beta-glucan & MOS complex) and $World-Labs^(R)$ (multiple probiotics) on the performance, nutrient availability, small intestinal microflora and immune response in broiler chicks, one thousand hatched broilers ($Ross^(R)$ were assigned to 4 treatments: control(basal diet), $BMD^(R),\;Safmannan^(R)\;and\;World-Labs^(R)$. There were no significant differences in the performance and in serum IgG, ND titre. However parameters of leukocytes and erythrocytes were significantly different among treatments (p<0.05). Leukocytes and RBC of $World-Labs^(R)\;and\;Safmannan^(R)$ were mostly lower than $BMD^(R)$ and control whereby MCH and MCHC of $World-Labs^(R)\;and\;Safmannan^(R)$ were higher than other treatments. The cfu of intestinal microflora had no significant differences among treatments. The $BMD^(R)$ treatment was higher than others in amino acid and crude fat availability and $World-Labs^(R)$ was higher than others in crude fiber availability. It was concluded that supplements used in the present experiment did not significantly affect the production parameters. However, significant impact on blood parameters, especially on leucocytes, may need further investigation.