• Nuclear Engineering and Technology
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• v.40 no.7
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• pp.593-606
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• 2008

In this study, data on radionuclide migration and retardation processes in the engineered and natural barriers of High-Level Radioactive Waste (HLW) repository have been reviewed and compiled for use in the performance assessment of a HLW disposal system in Korea. The status of the database on radionuclide migration and retardation that is being developed in Korea is investigated and summarized in this study. The solubilities of major actinides such as D, Th, Am, Np, and Pu both in Korean bentonite porewater and in deep Korean groundwater are calculated by using the geochemical code PHREEQC (Ver. 2.0) based on the KAERI-TDB(Korea Atomic Energy Research Institute-Thermochemical Database), which is under development. Databases for the diffusion coefficients ($D^b_e$ values) and distribution coefficients ($K^b_d$ values) of some radionuclides in the compacted Korean Ca-bentonite are developed based upon domestic experimental results. Databases for the rock matrix diffusion coefficients ($D^r_e$ values) and distribution coefficients ($K^r_d$ values) of some radionuclides for Korean granite rock and deep groundwater are also developed based upon domestic experimental results. Finally, data related to colloids such as the characteristics of natural groundwater colloids and the pseudo-colloid formation constants ($K_{pc}$ values) are provided for the consideration of colloid effects in the performance assessment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.4
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• pp.103-113
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• 1987

Fatigue tests using a single-peak loading and a two-step loading were carried out to examine the fatigue crack growth behaviar and to find the appropriate analysis method. C-T specimens were made using structural steel SWS58 for the tests. From this, just after a single-peak loading acceleration effect was occured and after some times retardation effect was found. And eminent retardation effect was found after High-Low two-step loading. The transition effect of crack growth due to this variable loading was occured owing to the residual stress and the plastic zone size at the crack tip. And the behaviors of these are well explained by Elber's Crack Closure Model. Also I could find that the Wheeler's Retardation Model is a simple and appropriate theory among analysis methods of fatigue crack growth under the variable loading.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.11 no.2
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• pp.76-80
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• 2015

Mental retardation is one of the major disorders covered in special care dentistry. Patients show poor oral health and are a challenge for the dentist due to lack of cooperation. Triazolam is a short-acting benzodiazepine and has been used in the dental office for many years because of its favorable properties. In this study, five patients with mental retardation were sedated with triazolam on a dental out-patient setting. Patients were administrated with 0.25 mg or 0.5 mg of triazolam on the first dose according to the patient's cooperation. Twenty minutes after the initial dose, patients received 0.25 mg of triazolam. Triazolam was administrated sublingually to one patient and orally to four patients. Hydroxyzine was also administrated to three patients in order to prevent nausea and vomiting. All patients were inhaled with 50% nitrous oxide during the sedation. Treatment time ranged from 20 minutes to 55 minutes. Two patients showed paradoxical reactions and were administrated with intramuscular injections of flumazenil. In result, depending on the range of dental treatment and level of intellectual disability, we can assume that triazolam may be beneficial for sedation in disabled patients.

• Tuberculosis and Respiratory Diseases
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• v.71 no.6
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• pp.476-479
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• 2011

The Streptococcus milleri group, which also includes S. anginosus, S. intermedius and S. constellatus, is found in the oropharynx, upper respiratory tract, gastrointestinal tract, and urogenital tract mucosa. Bacteria in the Streptococcus milleri group are associated with bacteremia and abscess formation. Most of the reports of of Streptococcus milleri group (SMG) infection occur in patients with underlying medical conditions. Predisposing factors that have been associated with S. milleri group empyema include mucosal disturbances (sinusitis, periodontal disease, enteric disease), preceding to pneumonia, thoracic surgery, malignancy, neurological disease, alcohol abuse, and also diabetes mellitus. We report on a 42-year-old man with mental retardation. He who suffered from dyspnea and a fever that he had developed for over 14 days. S. constellatus and anaerobic bacterias (Prevotella buccae and Micromonas micros) were cultured. The patient was treated with the drainage of pleural effusion and clindamycin and levofloxacin.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.3 no.1
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• pp.17-21
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• 2007

Alagille syndrome is an autosomal dominant genetic disorder and occurs in approximately 1 in 100,000 live births. Diagnostic criteria was established by Alagille. It is mainly caused by a mutation in the Jagged1 gene. Major clinical features of this syndrome are paucity of intrahepatic bile duct with cholestasis, characteristic facies, cardiac murmur, defects of vertebrae, and embryotoxon. And minor clinical features are mental retardation, renal involvement, growth retardation, other skeletal abnormalities, a high-pitched voice. The surviving prognosis of Alagille syndrome patients depends on the severity of cardiovescular malformation in the early ages of infant. However, with the increasing years, it depends on the severity of the liver disease. Cholestasis causes congenital jaundice, malnutrition and growth retardation. Also, the increase of serum cholesterol level cause xanthoma and pruritus. Even though the severity of these problems are reduce with age, there is cases where there is no way but liver transplantation. For oral features of Alagille syndrome patients, green discoloration of entire dentition, induced by bilirubin infiltration into dentinal tubules, is especially. Also, xanthoma on gingiva and partial hypodontia have been reported. This report is on the oral features of an Alagille syndrome patient who visited to Kyung-Pook University Hospital.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.6
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• pp.835-842
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• 2009

The present thesis carried out a research on a compression pressure's reduction phenomenon and its countermeasure according to the thermal efficiency improvement method by a Miller method in 4-cycle low speed diesel engine. In case of retardation of intake valve closing time in a engine, the theoretical heat efficiency shows a remarkably reducing trend when a compression ratio is not compensated. Accordingly, the thermal efficiency showed an increasing trend in case of compensating the compression ratio. Especially, it could be understood that the theoretical heat efficiency at near ABDC $100^{\circ}$ of intake valve closing time in case of compensation of the compression ratio was improved by around 25.1%, and the mean effective pressure was also increased by around 18.6%. Also, as the retardation of intake valve closing time increases, air quantity becomes insufficient due to a backflow phenomenon of intake air and thus thermal efficiency was decreased in a high load operation domain. The solving method of this problem is possible by supercharge. Therefore, in order to improve thermal efficiency by retardation of ntake valve closing time, the thermal efficiency improvement according to low compression is possible when there are a compensation device of a compression ratio and a supercharge device. This is a problem-solving method of low compression and high expansion cycle.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.13-21
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• 1992

The inhibitory effects of mercury ions on the growth of barley seedlings were studied and the distribution of metal elements in the organs of treated plants was investigated by using synchrotron radiation induced X-ray emission (SRIXE). Although the treatment of mercury ions caused growth inhibition, the mercury-specific increase in variable fluorescence and the abolishment of energy-dependent quenching in broken barley chloroplasts as shown by Moon et at. (1992) were not observed in the leaves of growth-inhibited seedlings. Instead the treatment of mercury decreased Fmax and Fo values. However, Fmax/Fo ratio and photochemical and nonphotochemical quenching coefficients were not affected significantly. By SRIXE analysis of $10\mu\textrm{m}$ mercury chloride treated seedlings, accumulation of mercury in roots was observed after 1 hour of treatment and similar concentration was sustained for 48 hours. Relative contents of mercury was high in roots and underground nodes where seeds were attachedl but was very low in leaves. Iron and zinc were also distributed mainly in the lower parts of the seedlings. However after 72 hours of treatment the contents of these metals in roots decreased and their distribution became more uniform, which may lead to death of the plants. These results suggest that the observed inhibitory effects on barley seedlings upto 48 hours after the treatment is not due to direct damages in the photosynthetic apparatus, but due to its accumulation in roots and the consequent retardation of the growth of barley seedlings. The decrease in Fmax and Fo is probably due to the decrease in chlorophyll and protein contents caused by the retardation of growth. The observed slow expansion of primary leaves could be also explained by the retardation of growth, but the fluorescence induction pattern from the leaves did not show characteristic symptoms of leaves under water stress.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.13 no.2
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• pp.98-103
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• 2013

Purpose: MAT-I/III deficiency by MAT1A gene mutation causes isolated hypermethioninemia, which is considered to be a clinically benign disease. But in some patients, mental retardation, developmental delay, myelination disorder may be shown. This study was performed to find out the clinical manifestations and genetic characteristics of patients with isolated hypermethioninemia. Methods: Clinical, biochemical and genetic analysis were done to 10 patients with isolated hypermethioninemia who were referred to department of pediatrics, Soonchunhyang University Hospital from March 1999 to March 2012. Results: At first visit, all patients' mean plasma methionine level was 5.5 mg/dL (2.1-14.6) and there were no increase of amino acid levels including homocystine in all patients. Serum homocysteine level was evaluated in seven patients who visited after year 2003, and ranged from 4.96 to $11.15{\mu}mol/L$ (normal < $25{\mu}mol/L$). Methionine restricted diet was started to all patients. Nine patients who managed regularly showed normal development, but one patient whose initial plasma methionine level was 14.6 mg/dL showed language delay at 1 year of age and was diagnosed as mild mental retardation (IQ=66) at 6 years of age. Genetic analysis was done to eight patients, R264H mutation was identified in seven patients. Also, both R299C and R356Q mutation were identified in one patient. Conclusion: Clinical findings in patients with isolated hypermethioninemia were generally good, but one patient showed mental retardation and language difficulty. R264H mutation which usually inherits as an autosomal dominant trait was most frequently found in our patients, and R299C/R356Q mutation were also identified.

• Journal of Advanced Marine Engineering and Technology
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• v.8 no.1
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• pp.49-63
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• 1984

The 5086-H116 Al-Alloy plate specimens having an edge through-thickness notch were investigated to find out the characteristics of the corner crack propagation by the plane bending fatigue. The experiments were also carried out in order to clarify the change of the corner crack propagation behaviour due to the various materials and their thicknesses. In addition, the retardation effect of overload on the corner crack propagation was quantatively studied. Main results obtained are as follows; 1. In the case of estimating the crack propagation rate of the corner crack, it is more reasonable to consider the growth rate of fracture surface area than that of crack length. 2. The shape of the corner crack growing in the plane plate under the bending fatigue can be estimated. 3. The crack propagation rate increases with the increasing of the thickness and the decreasing of the Young's modulus of materials. 4. Regardless of a thickness and kind of materials of specimen, the characteristics of the corner crack propagation can be concluded. 5. The retardation effect of overload is distinct in the corner crack propagation.

• Journal of Environmental Science International
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• v.12 no.7
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• pp.801-807
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• 2003

This work aims the search of environmentally friendly pre-treatment technologies to develop chromate replacements for metal finishing industries due to its toxicological properties. Since the corrosion resistance of steel was strongly related to water permeation, galvanized steel sheets were treated with various hydrophobic silane compounds and water-suspended polymer solution. Also, plasma gas discharge was applied to modify the surface of a polymer coated-steel sheet to be hydrophobic. The surface hydrophobicity of materials was introduced by CF$_3$H plasma exposure. The corrosion property before and after the plasma treatment was investigated in a slat spray tester with 3.5 wt.% NaCl at 35$^{\circ}C$. The results showed that both silane/polymer double coatings and plasma treatment of the galvanized steel exhibited significant retardation of corrosion.