• The korean journal of orthodontics
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• v.26 no.3
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• pp.317-324
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• 1996

This study was conducted to evaluate the tensile bond strength of three commercially available glass ionomer cements as orthodontic bracket adhesives. 120 premolars extracted for orthodontic treatment were prepared for bonding and standard edgewise brackets were bonded with Shofu Glaslonomer Cement (Shofu Co., U.S.A.), GC Fuji ItGC Co., Japan), KETAC-CEM(ESPE Co., West Germany) with different P/L ratio. The tensile bond strength was tested by Instron testing device after 24hours and 3months from bonding. After debracketing, bracket bases were examined to determine the failure sites. The results of this study were as follows: 1. KETAC CEM showed the highest bond strength other than measurement after 24 hours and at its original P/L ratio, and seemed to have clinically a proper bond strength. It seemed, however, that both Shofu Giaslonomer Cement and GC Fuji I had an inappropriate bond strength. 2. The incorporation of additional powder into the mixture improved the tensile bond strength. 3. Prolonged storage time improved the tensile bond strength. 4. Of the failure, failure occured at the tooth-adhesive interface(54.2%) was the most common type. The second type of failure(36.7%) was combination type, where part of the adhesive remained on the tooth and part on the bracket. And the last type of failure(9.1%) occured at the adhesive-bracket interface.

• Journal of Periodontal and Implant Science
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• v.32 no.3
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• pp.643-653
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• 2002

Periodontal supporting tissue goes through destruction by chronic inflammatory periodontal disease as two aspect. One is qualitive aspect such as alteration of periodontium, the other is quantitative aspect such as alveolar bone loss. According to many authors, PDL is responsible for biting force, and there are two mean. for measuring PDL's function - mobility test and biting force test. This study was conducted to compare the biting force with remaining bone level, that is, quantitative aspect of periodontium, in anterior and premolar teeth at periodontal maintenance phase. 17 patients on periodontal maintenance phase during 6 months at minimum were selected for this study. For the same condition, 4 anterior, canine, premolar teeth were tested by MPM-3000 bite-force register at the same time(a.m.l0-12), the same position, the same posture, by the same examiner. Patients of TMI), ill-fitting pros thesis, general disease, malocclusion and the teeth of TFO, absence of opposing teeth, malposition were excluded. Remaining bone level was measured on the panorama X-ray film through 5 level from 1mm below CEJ to root apex. Teeth were examined twice, and bigger one was selected. If the values showed large difference. examinatin was re-done and the mean was selected. The results were as follows ; 1. In the 4 anterior group, as the remaining bone is decreased, the average of maximal biting force is decreased. Especially, at 3/5 bone level, maximal biting force is decreased significantly(p<0.01). 2. In the canine group, as the remaining bone is decreased, the average of maximal biting force is decreased. Especially, at 2/5 bone level, maximal biting force is decreased significantly(p<0.01). 3. In the premolar group, as the remaining bone is decreased, the average of maximal biting force is decreased. Especially, at 3/5 bone level, maximal biting force is decreased significantly(p<0.05). From the results of this study, clinicians could utilize these efficiently when they have to determine the proper restorative materials, time for tooth extraction, treatment plan, prognosis.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.1
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• pp.35-41
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• 2014

Trihalomethanes (THMs) are formed as a results of the reaction of residual chlorine, used as a disinfectant in drinking water, with the organic matter in raw water. Although chlorinated and brominated THMs are the most common disinfection byproducts (DBPs) reported, iodinated THMs (I-THMs) can be formed when iodide is present in raw water. I-THMs have been usually associated with several medicinal or pharmaceutical taste and odor problems and is a potential health concern since they have been reported to be more toxic than their brominated and chlorinated analogs. Currently, there is no published standard analytical method for I-THMs in water. An automated headspace-gas chromatography/electron capture detector (GC/ECD) technique was developed for routine analysis of 10 THMs including 6 I-THMs in water samples. The optimization of the method is discussed. The limits of detection (LOD) and limits of quantification (LOQ) range from 12 ng/L to 56 ng/L and from 38 ng/L to 178 ng/L for 10 THMs, respectively. Matrix effects in river water, sea water and wastewater treatment plant (WWTP) final effluent water were investigated and it was shown that the method is suitable for the analysis of trace levels of I-THMs, in a wide range of waters. The method developed in the present study has the advantage of being rapid, simple and sensitive.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.4
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• pp.335-344
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• 2006

In this paper a computer program was developed, which simulates the Li reduction process of PWR spent fuel, and the amount of a produced metal or chloride compound was calculated at the various amount of Li with the program. It establishes a database, which is composed of some characteristics related to a chemical reaction equation and thermodynamic data, and it calculates the transformed rate of PWR spent fuel oxide at the certain amount of Li by using the database as input data. As the results of the performance test of the program, it was validated that the transformed values of oxides, except for $Eu_2O_3$ and $Sm_2O_3$, were almost the same to within about a 6 % error with those calculated by the previous code and that the calculated amount of Li was also exactly consistent with the theoretical one, which is used for a complete reaction of each oxide in a single chemical reaction. A relationship between Li and the transformed metal of each oxide was analyzed on the basis of the quantities calculated with the verified development program. Of the results, when the amount of Li was given to be 250 mole, the 83.73 percentage of $UO_2$ was transformed into U while the remainder was still to be $UO_2$. In addition, it was appeared that the 297 mole of Li was needed to completely convert $UO_2$ into U.

• 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.

• Korean Journal of Food Science and Technology
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• v.22 no.3
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• pp.343-349
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• 1990

The solubility of protein and phytate was measured at various pH's in distilled water and at various concentrations of NaCl, $CaCl_2\;and\;Na_2SO_3$ solutions, and then optimum condition for producing low phytate protein isolate from perilla flour was investigated. The protein solubility in water showed minimum at pH 4.0 and increased at pH higher or lower than 4.0, while phytate solubility was highest at pH 5.0 and decreased at pH higher or lower than 5.0. In NaCl solution, protein solubility was lowest between pH 3.0-4.0, while phytate solubility was high between pH 2.0-5.0 and abruptly decreased above PH 6.0. In $Na_2SO_3$ solution, protein solubility was lowest between pH 2.0-3.0 and phytate solubility showed maximum values between pH $5.0{\sim}6.0$, and it's solubility was low in 3% salt concentration at all pH ranges. In $CaCl_2$ solution, protein solubility in 3% salt concentration was relatively low at all pH ranges, and phytate solubility showed highest values between pH $2.0{\sim}3.0$ and abruptly decreased (1.0%) above pH 4.0. In order to make low phytate protein isolate, defatted perilla flour protein was extracted at pH9.0 and precipitated at pH 4.0 in 3% NaCl solution. The yield of low phytate protein isolate was 61.4% of total protein. This protein was found to contain 0.02% phytate by weight.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.1
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• pp.49-56
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• 2016

Excessive occlusal wear can result in unacceptable damage to the residual teeth structure, anterior guidance and masticatory function. An 86-year-old man presented with worn dentition and anterior deep bite due to loss of the posterior support. Two implants covered by Korean national health insurance, fixed partial denture and direct composite resin were used to restore the dentition, instead of removable prosthesis. The occlusal vertical dimension was increased by 2 mm in the premolar area and shortened dental arch concept was applied. This treatment was a less expensive alternative to full-mouth rehabilitation with positive esthetic and functional outcomes after 7 months of follow-up.

• Journal of Korean Society of Forest Science
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• v.98 no.1
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• pp.1-7
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• 2009

We investigated the genetic variation and structure in Korean Arborvitae (Thuja koraiensis Nak.), by 29 examining I-SSR polymorphic loci in 84 individuals distributed among four natural populations in Korea. The level of population genetic diversity ($A_e$=1.44, P=72.42, $H_e$=0.258, S.I.=0.385) was similar to or slightly higher than that of plants with similar ecological traits and life history (Cupressaceae). Most genetic diversity was allocated among individuals within populations (${\Phi}_{ST}$=0.13). The UPGMA dendrogram based on genetic distance failed in showing decisive geographic relationship. The Mt. Bangtae population had the lowest level of genetic diversity and was the most distinctive from the other populations. Mt. Jang population which is possessed of the highest level of genetic variation and Mt. Bangtae population which is consisted of heterogeneous was considered to be a prime candidate for the conservation studies.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.3
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• pp.457-478
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• 1992

Electrical resistance strain gauges, brittle-coatings, Moir'e fringe analysis, photoelasticity methods, etc, have been employed in the study of stress analysis and three-dimensional photoelasticity method used in this experiment. The author fabricated a total of 24 samples of maxillary and mandibular edentulous ridges with normal and sharp shapes using epoxy resin, one of the photoelastic materials. In addition, complete denture made from artificial resin teeth in other twoo sizes, large and medium size, were affixed to the specimens and attached to an articulator. The following results were attained by cutting 9 slice specimens into 6mm thick portions, in accordance with the three dimensional photoelastic stress freezing method, to analyze stress distribution status under specific static loading in the central, lateral and protrusive occlusions of the shape of edentulous ridge. 1. In the case of central occlusion, when complete resin artificial teeth in large and medium sizes were used on normal and sharp alveolar ridges, high stress distribution was broadly shown in the labio-buccal sides, and low and concentrated in the lingual sides, in all cases. Generally, the highest stresses were shown at the top of the alveolus, or at 2mm below the top of the alveolus, particularly in the specimen 2, 3, and stresses were more or less the same in the symmetrical right and left sides. 2. In the case of lateral occlusion, when the same load was applied, high stresses were shown broadly at the working sides in both the labio-buccal and lingual sides, and low and concentrated at the balanced sides. The highest stresses were shown in the top of the alveolus on the working sides in specimen 2 portion, and the lowest stresses at the balanced sides in specimen 6, slightly higher stresses were shown at retromolar parts in the balanced sides. 3. In the case of protrusive occlusion, high stresses were broadly shown at the labio-buccal sides, and slightly higher stresses at the top 2, 4, and 6mm parts of the alveolus with concentration. The highest stresses were shown in specimen No. 5 and the lowes stresses in specimen 1, 9 and stresses were more of less the same at the symmetrical right and left sides.

• Microbiology and Biotechnology Letters
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• v.13 no.4
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• pp.355-359
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• 1985

The purified $\beta$-galactosidase from L. sporogenes was most active at pH 7.0 and 6$0^{\circ}C$ with O-nitrophenyl-$\beta$-D-galactopyranoside (ONPG) in 0.05 M phosphate buffer. It was stable over a pH range from 5.0 to 9.0 and lost less than 10％ of its activity after heating for 30 minutes at 6$0^{\circ}C$ and pH 7.0. All the mineral ions examined in this work showed no significant activating effect, whereas L-cysteine exerted a great stimnlatory effect on the enzyme activity at the concentration of 10 mM. The Km values were 1.2 mM for ONPG and 33.3 mM for lactose. Approximately 85％ of lactose in cow's milk, in 10％ skim milk and in 5％ lactose solution was hydrolyzed after 4 hours incubation at 6$0^{\circ}C$ with 2 units of the purified $\beta$-galactosidase per $m\ell$ of the substrate solutions. The $\beta$-galactosidase from L. sporogenes, therefore, is considered to be suitable for hydrolysis of lactose in milk and other dairy products.