• Journal of the Korean Geosynthetics Society
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• v.12 no.1
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• pp.39-50
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• 2013

This study aims at investigating the behavior of the ground water level when installing upward soil nails that drain water as well. To do this, a series of down-scaled model tests were conducted. A model slope with weathered soils was prepared and then an artificial rain was scattered on the slope. The relative densities of soil specimen were 60%, 75%, and 90%, and the rainfall intensities 50mm/hr, 75mm/hr, 100mm/hr, and 125mm/hr, respectively. The experimental parameters, such as the ground water level, ratio of soil runoff, and failure mode of the slope were measured and analyzed. As the results, It may be concluded that the ground water level in the slope supported by drainable upward soil nails increases very gradually while the unsupported soil changes dramatically. In addition, the ground water level becomes constant and no failure occurs as time goes by. In case of the relative density of 75%, the runoff ratio seemed to increase up to about 8~15% after reinforcement.

• Journal of Navigation and Port Research
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• v.40 no.3
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• pp.159-164
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• 2016

The goal of this study is to implement a communication system that can monitor the status of the nacelle using the power cable itself, without the dedicated communication lines such as an UTP cable and optical fiber for the offshore wind turbine. An inductive coupling powerline communication system for a MW class offshore wind turbine was proposed and its communication performance was demonstrated. The inductive couplers was designed for operation at up to 500 A using a ferrite composite materials. Field test was carried out on the wind farms of Jeju island. Using the iperf communication test program, we have obtained more than 15 Mbps data transmission rate through the 100 m power cable that was installed between the nacelle and the bottom of the power converter. In the data transmission stability test for a week, there was no failure ever. The minimum transmission rate was 15 Mbps and the average data rate was about 20 Mbps. Next, we have installed an infrared camera inside the nacelle in order to measure the temperature distribution and variation of the nacelle. The real-time thermal image taken by the camera was successfully sent to the monitoring system without error.

• Childhood Kidney Diseases
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• v.10 no.2
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• pp.152-161
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• 2006

Purpose : In Korea, the school urine screening program is a useful tool for screening urine abnormalities. It is particularly useful in early detection of membranoproliferative glomerulonephritis(MPGN) I, which frequently progresses to chronic renal failure. In this study, we studied the medical history, laboratory findings, and histologic findings of MPGN to gain helpful information on early detection and treatment. Methods : The subjects were 19 children, who were diagnosed with MPGN from kidney biopsies that were performed in ten nationwide university hospitals because of abnormal urine findings from school urine screening programs conducted from July 1999 to April 2004. We divided the patients into 2 groups, a nephrotic range proteinuria group(n=8) and a non-nephrotic proteinuria group(n=11), and retrospectively analyzed the clinical features, laboratory findings, histologic findings, treatment, and clinical course. Results : The mean age at the first abnormal urinalysis was $10.6{\pm}2.2$ years in the nephrotic proteinuria group and $9.6{\pm}3.2$ years in the non-nephrotic proteinuria group. The mean age at the time of kidney biopsy was $11.3{\pm}2.3$ years in the nephrotic range proteinuria group and $10.4{\pm}3.2$ years in the non-nephrotic proteinuria group respectively. There was no significant difference in the mean age and sex between the two groups. In the nephrotic proteinuria group, 6 children had a low plasma C3 level and in the non-nephrotic proteinuria group, 8 children had a low plasma C3 level, but there was no significant difference between the 2 groups. There was no significant difference in the laboratory test results(including WBC count, RBC count, platelet count and other serologic tests) between the 2 groups except for 24 hour urine protein secretion. There was no difference between the 2 groups with regard to the acute and chronic changes in the glomerulus on light microscopic findings, IgG, IgA, Ig M, C1q, C3, C4, fibrogen deposition on immunofluoroscence findings, and mesangial deposits, subendothelial deposits, and subepithelial deposits on electron microscopic findings. The children were treated with corticosteroids, ACE(angiotensin-converting enzyme) inhibitors, dipyridamole and other immunosuppressive agents. During the course of treatment, there were no children whose clinical condition worsened. Among 19 children, 3 children went into remission(2 in the nephrotic proteinuria group, 1 in the non-nephrotic proteinuria group) and 9 children went into a partial remission(4 in the nephrotic proteinuria group, 5 in the non-nephrotic proteinuria group) on urinalysis. There was no significant difference in the treatment results between the two groups. Conclusion : The 73.7% of children who were incidentally diagnosed with MPGN by the school urine screening program had reduced C3. 42.1% of the children had nephrotic range proteinuria. There were no significant differences in clinical features, laboratory test results, light microscopic, immunofluorescence microscopic, and electron microscopic findings between the nephrotic proteinuria group and the non-nephrotic proteinuria group except for the 24 hour urine protein secretion. Therefore, for early detection of MPGN during the school urine screening program, we strongly recommend a kidney biopsy if children have abnormal urine findings such as persistent proteinuria and persistent hematuria, or if the serum C3 is reduced.

• Restorative Dentistry and Endodontics
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• v.32 no.2
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• pp.130-137
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• 2007

This in vitro study examined the effect of surface defects on cutting blades on the extent of the cyclic fatigue fracture of HEROShaper Ni-Ti rotary files using fractographic analysis of the fractured surfaces. A total of 45 HEROShaper (MicroMega) Ni-Ti rotary flies with a #30/.04 taper were divided into three groups of 15 each. Group 1 contained new HEROShapers without any surface defects. Group 2 contained HEROShapers with manufacturing defects such as metal rollover and machining marks. Croup 3 contained HEROShapers that had been clinically used for the canal preparation of 4-6 molars A fatigue-testing device was designed to allow cyclic tension and compressive stress on the tip of the instrument whilst maintaining similar conditions to those experienced in a clinic. The level of fatigue fracture time was measured using a computer connected the system. Statistical analysis was performed using a Tukey's test. Scanning electron microscopy (SEM) was used for fractographic analysis of the fractured surfaces. The fatigue fracture time between groups 1 and 2, and between groups 1 and 3 was significantly different (p<0.05) but there was no significant difference between groups 2 and 3 (p>0.05). A low magnification SEM views show brittle fracture as the main initial failure mode At higher magnification, the brittle fracture region showed clusters of fatigue striations and a large number of secondary cracks. These fractures typically led to a central region of catastrophic ductile failure. Qualitatively, the ductile fracture region was characterized by the formation of microvoids and dimpling. The fractured surfaces of the HEROShapers in groups 2 and 3 were always associated with pre-existing surface defects. Typically, the fractured surface in the brittle fracture region showed evidence of cleavage (transgranular) facets across the grains, as well as intergranular facets along the grain boundaries. These results show that surface defects on cutting blades of Ni-Ti rotary files might be the preferred sites for the origin of fatigue fracture under experimental conditions. Furthermore this work demonstrates the utility of fractography in evaluating the failure of Ni-Ti rotary flies.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.227-235
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• 2018

Along with the recent increase in traffic volume of vehicles, accidents involving rollover of vehicles have been rapidly increased, resulting in an increase casualties. And to prevent this, various technologies such as vehicle crash test equipment and analysis program development have been advanced. In this study, the applied vehicle model is FORD EXPLORER model, and PC-Crash program for vehicle collision analysis is used to predict the rollover accident behavior of SUV and the collision velocity. Compared with the actual rollover behavior of SUV through the FMVSS No 208 regulations, the analysis results showed similar results, the characteristics of the collision velocity and roll angle showed a tendency that the error rate slightly increased after 1000 msec. Then, as a result of considering using the database of NHTSA, it is shown that the rollover accident occur most frequently in the range of the collision velocity of 15~77 km/h and the collision angle of $22{\sim}74^{\circ}$. And it is possible to estimate the vehicle speed and collision time when the vehicle roof is broken by reconstructing the vehicle starting position, the roof failure position and the stop position by applying the actual accident case.

• Journal of Distribution Science
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• v.12 no.4
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• pp.11-22
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• 2014

Purpose - The domestic franchise industry has made significant contributions to industry such as investment, employment, and community economy development, facilitating growth potential. The franchise industry provides management knowhow transfer between parent companies and franchisees as per contracts addressing use of business signs, franchisees' independent position, franchisor support, and royalties to be paid to the franchisors. However, many franchisors lack management knowhow and provide insufficient support because of poor control of franchisees and not having a systematic approach to support. This results in dissatisfied franchisees and failure to establish long-term relationships. Few studies have examined relational commitment and/or re-contract intention by support resources between franchisors and franchisees, despite a considerable output of theories and studies of the growth of the franchise industry. The purpose of this study, therefore, was to examine the effects of the ability to provide resources on relational commitments and re-contract intention, and to suggest causal relationships and implications. Research design, data, and methodology - The subject was domestic franchisors registered with the Association of Franchise with more than 50 franchisees. Franchisees under contract for 2 years and considering re-contract of their franchise 2 years later were used. The subjects totaled 300 franchisees in Seoul. A questionnaire survey was used to investigate the subject of franchisees' concessions during the 10 days from November 21, 2013 to November 30, 2013. After excluding 16 surveys with poor answers, 284 responses were finally used. Four areas and 44 questions were used. A nominal scale was used for four common characteristics questions including gender, ages, educational background, and franchise managing time. Questions regarding ability, relational commitment, and re-contract intention made use of a Likert 5-point scale. Data coding and data cleaning were used. SPSS 18.0 was used as follows. First, frequency analysis was done to investigate demographic characteristics. Second, exploratory factor analysis was done to verify validity of testing tools, and Cronbach's α coefficient was used to verify reliability. Third, correlation analysis and multiple regression analysis were done. An exploratory factor analysis was done to verify validity of concepts. A correlation analysis was done to test relationships between the variables, and multiple regression analysis was done to verify franchisor's ability, franchisees' relational commitment, and re-contract intention. Results - The following were the outcomes. First, store operation management, finance operation management, and human resource management affected the calculated bond. Second, store operation management and finance operation management affected the emotional bond. Third, store operation management, finance operation management, human resource management, and marketing management affected the prescriptive bond. Fourth, calculated bond and prescriptive bond had an effect on re-contract intention. Conclusions - As stated above, in franchise management, parent companies' offer and instruction of core competence to their franchisees as an information resource could improve the relational bond by helping them grow together through the resource sharing. Consequently, core competence factors were promoting factors that could improve franchisees' re-contract intention for a long time.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.175-186
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• 1996

The purpose of this study was to examine the effects of mechanical and thermal fatigue on the shear bond strength(SBS) of stainless steel mesh brackets bonded to human premolar teeth with 3 no-mix adhesives. The stainless steel mesh bracket was Ormesh(Ormco, .022 slot) and three types of no-mix adhesives were Ortho-one(Bisco), $Monolok^2$(RMO), $System\;1^+$(Ormco). The $10^6$ loadcycles of $17.4{\times}10^2sin2{\pi}ftlg{\cdot}cm$ and the 1,000 thermocycles of 15 second dwell time in each bath of $5^{\circ}C\;and\;55^{\circ}C$ were acturated as mechanical and thermal fatigue stress, and SBS were measured after each fatigue test. The fracture sites were analyzed by stereoscope and scanning electron microscope. The results obtained were summarized as follows; 1. Before thermocycles, $Monolok^2$ showed the highest Knoop hardness number(KHN, $64.03kg/mm^2$) and $System\;1^+$ showed the lowest value($31.60kg/mm^2$). After thermocycling, $Monolok^2$ also showed the highest KHN($38.03kg/mm^2$) and $system\;1^+$ showed the minimum($20.87kg/mm^2$). The KHN of Ortho-one, $Monolok^2,\;System\;1^+$ significantly decreased after thermocycling (P<0.01). 2. In static shear bond test, three adhesives had no significant differences in the SBS(P>0.01). 3. After thermocycling test, $Monolok^2$ showed the maximum SBS($19.34{\pm}2.75MPa$) and Ortho-one showed the minimum SBS($13.66{\pm}2.23MPa$). The SBS of Ortho-one(P<0.01) and $System\;1^+$(P<0.05) significantly decreased after $10^3$ thermocycles. 4. The SBS of three adhesives after $10^6$ loadcycles were similar and were not significantly decreased compared with static group(P>0.01). 5. The failure sites were usually bracket/resin interface in all groups irrespective of experimental conditions.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.4
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• pp.312-316
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• 2014

Purpose: The aim of this study was to compare the fracture toughness of currently available resin cements for zirconia restorations and evaluate the effect of water storage on fracture toughness of those resin cements. Materials and methods: Single-edge notched specimens ($3mm{\times}6mm{\times}25mm$) were prepared from three currently available dual cure resin cements for zirconia restorations (Panavia F 2.0, Clearfil SA luting and Zirconite). Each resin cement was divided into four groups: immersed in distilled water at $37^{\circ}C$ for 1 (Control group), 30, 90, or 180 days (n=5). Specimens were loaded in three point bending at a cross-head speed of 0.1 mm/s. The maximum load at specimen failure was recorded and the fracture toughness ($K_{IC}$) was calculated. Data were analyzed using one-way ANOVA and multiple comparison $Scheff{\acute{e}}$ test (${\alpha}$=.05). Results: In control group, the mean $K_{IC}$ was $3.41{\pm}0.64MN{\cdot}m^{-1.5}$ for Panavia F, 2.0, $3.07{\pm}0.41MN{\cdot}m^{-1.5}$ for Zirconite, $2.58{\pm}0.30MN{\cdot}m^{-1.5}$ for Clearfil SA luting respectively, but statistical analysis revealed no significant difference between them. Although a gradual decrease of $K_{IC}$ in Panavia F 2.0 and gradual increases of KIC in Clearfil SA luting and Zirconite were observed with storage time, there were no significant differences between immersion time for each cement. Conclusion: The resin cements for zirconia restorations exhibit much higher $K_{IC}$ values than conventional resin cements. The fracture toughness of resin cement for zirconia restoration would not be affected by water storage.

• Journal of Pharmaceutical Investigation
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• v.33 no.4
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• pp.311-317
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• 2003

Felodipine is a calcium antagonist that lowers blood pressure by reducing peripheral resistance by meas of a direct, selective action on smooth muscle in arterial resistance vessels. Futhermore, it have been approved for the effective in angina pectoris and cardiac failure. The purpose of the present study was to evaluate the bioequivalence of two felodipine extended release (ER) tablets, Splendil (YuHan Corporation) and Stapin (Hana Pharmaceutial Co., Ltd.), according to the guidelines of Korea Food and Drug Administration (KFDA). The felodipine release from the two felodipine formulations in vitro was tested using KP VIII Apparatus II method at pH 6.5 buffer solution. Twenty six healthy male subjects, $22.73{\pm}1.78$ years in age and $66.66{\pm}7.28\;kg$ in body weight, were divided into two groups and a radomized $2{\times}2$ cross-over study was employed. After two tablets containing 5 mg as felodipine were orally administered, blood sample was taken at predetermined time intervals and the concentrations of felodipine in serum were determined using column-switching HPLC method with UV detector. The dissolution profiles of two formulations were similar at pH 6.5 buffer solution. Besides, the pharmacokinetic parameters such as $AUC_t,\;C_{max}\;and\;T_{max}$ were calculated and ANOVA test was utilized for the statistical analysis of the parameters using logarithmically transformed $AUC_t\;and\;C_{max}$ and untransformed $T_{max}$. The results showed that the differences between two formulations based on the Splendil were 2.53%, 1.32% and 18.32% for $AUC_t,\;C_{max}\;and\;T_{max}$, respectively. There were no sequence effects between two formulations in these parameters. The 90% confidence intervals using logarithmically transformed data were within the acceptance rage of log(0.86) to log(1.25) $(e.g.,\;log(0.86){\sim}log(1.20)\;and\;log(0.89){\sim}log(1.23)\;for\;AUC_t,\;C_{max},\;respectively)$. Thus, the criteria of the KFDA guidelines for the bioequivalence was satisfied, indicating Stapin ER tablet and Splendil ER tablet are bioequivalent.

• Journal of Preventive Medicine and Public Health
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• v.34 no.2
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• pp.131-140
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• 2001

Objectives : During March-May, 2000, a measles outbreak occurred at Youngduk, Korea. This county is divided into two areas with different historical and socioeconomic background. The outbreak occurred in one of these areas. We conducted a comparative epidemiologic study on the two areas in order to evaluate the factors related to the epidemic. Materials and Methods : We selected two groups, grades 3 and 5 in a primary schools in each area. We investigated outbreak-related factors using parent-questionnaires, the vaccination history from the student's health record and the records concerning the recent measles-outbreak from the local health center. Serologic test on measles-IgG and -IgM antibody was done. Results : The infection rate was 31.5% for the epidemic area and 3.7% for non-the epidemic area according to clinical or serological criteria (p<0.001). No difference was seen in the measles vaccination rate, residence at the time of vaccination or past measles infection history between the two areas. In the epidemic area, the attack rate for the 4-6 year-old MMR booster group(20.5%) was higher than the non-booster group(32.4%), but was not found significantly. Vaccine efficacy was 29.6% in the epidemic area and 87.0% in the non-epidemic area (p<0.001). The IgG level and positive rate were significantly different between the two areas (median 10727 IU/ml, 98.9% in epidemic area; median 346 IU/ml, 85.9% in the non-epidemic area, p<0.001). However, the IgG level and positive rate between the measles-cases and non-cases were not significantly different. Conclusions : This outbreak took place in mostly vaccinated children. These results suggest that a reduction of herd immunity for immunity failure after vaccination may be one of the feasible factors related to the outbreak pattern in the two areas. The results of the IgG level and positive rate suggest that re-establishment of a normal value for IgG level and of a qualitative method for IgG are needed.