• Journal of the Korean Society of Radiology
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• v.6 no.2
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• pp.93-98
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• 2012

Micro-computed tomography (microCT) is an important tool for preclinical vascular imaging, with micron-level resolution. This non-destructive means of imaging allows for rapid collection of 2D and 3D reconstructions to visualize specimens prior to destructive analysis such as pathological analysis. Objectives. The aim of this study was to suggest a method for ex vivo, postmortem examination of stented arterial segments with microCT. And ex vivo evaluation of stents such as bare metal or drug eluting stents on in-stent restenosis (ISR) in rabbit model was performed. The bare metal stent (BMS) and drug eluting stent (DES, paclitaxel) were implanted in the left or right iliac arteries alternatively in eight New Zealand white rabbits. After 4 weeks of post-implantation, the part of iliac arteries surrounding the stent were removed carefully and processed for microCT. Prior to microCT analysis, a contrast medium was loaded to lumen of stents. All samples were subjected to an X-ray source operating at 50 kV and 200 ${\mu}A$ by using a 3D isotropic resolution. The region of interest was traced and measured by CTAN analytical software. Objects being exposed to radiation had different Hounsfield unit each other with values of approximately 1.2 at stent area, 0.12 ~ 0.17 at a contrast medium and 0 ~ 0.06 at outer area of stent. Based on above, further analyses were performed. As a result, the difference of lengths and volumes between expanded stents, which may relate to injury score in pathological analysis, was not different significantly. Moreover, ISR area of BMS was 1.6 times higher than that of DES, indicating that paclitaxel has inhibitory effect on cell proliferation and prevent infiltration of restenosis into lumen of stent. And ISR area of BMS was higher ($1.52{\pm}0.48mm^2$) than that of DES ($0.94{\pm}0.42mm^2$), indicating that paclitaxel has inhibitory effect on cell proliferation and prevent infiltration of restenosis into lumen of stent. Though it was not statistically significant, it showed that the extent of neointema of mid-region of stents was relatively higher than that of anterior and posterior region in parts of BMS as showing cross-sectional 2-D image. suggest that microCT can be utilized as an accessorial tool for pathological analysis.

• Journal of Korean Society for Quality Management
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• v.5 no.2
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• pp.59-120
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• 1977

An antibiotic 'P', which is one of the products of the Gist Brocades N. V. is being tested by its research department as fungicide on seed-potatoes. For this testing they designed experiments, with two control groups, one competitor's product, eight formulations of the antibiotic to be tested in different concentrations and one mercury treatment which can not be used in practice. The treated potatoes were planted in three different regions, where bifferent conditions prevail. After several months the harvested potatoes are divided in groups according to their diameter, potato illness is analysed and counted. These data were summarised in percentage and given to us for Analysis. We approached and analysed the data by following methods: a. Computation of the mean and standard deviation of the percenage of good results in each size group and treatment. b. Computation of the experimental errors by substraction of each treatment mean from observed data. c. Description of the frequency table, plotting of a histogram and a normal curve on same graph to check normality. d. Test of normality paper and chi-sqeare test to check the goodness of fit to a normal curve. e. Test for homogeneity of variance in each treatment with the Cochran's test and Hartley's test. f. Analysis of Variance for testing the means by one way classifications. g. Drawing of graphs with upper and lower confidence limits to show the effect of different treatments. h. T-test and F-test to two Control mean and variance for making one control of Dunnett's test. i. Dunnett's Test and calculations for numerical comarision of different treatments wth one control. In region R, where the potatoes were planted, it was this year very dry and rather bad conditions to grow potatoes prevailed during the experimental period. The results of this investigation show us that treatment No.2, 3 and 4 are significantly different from other treatments and control groups (none treated, just like natural state). Treatment no.2 is the useless mercury formulation. So only No. 3 and 4, which have high concentrations of antibiotic 'P', gave a good effect to the potatoes. As well as the competitors product, middle and low concentrated formulations are not significantly different from control gro-ups of every size. In region w, where the potatoes got the same treatments as in region R, prevailed better weather conditions and was enough water obtainable from the lake. The results in this region showed that treatment No. 2, 3, 4, and 5 are Significantly different from other treatments and the control groups. Again No.2 is the mercury treatmentin this investigation. Not only high concentrated formulation of antibiotic 'P', but also the competitor's poroduct gave good results. But, the effect of 'P', was better than the competitors porduct. In region G, where the potatoes got the same treatments as in the regions R and w. and the climate conditions were equal to region R, the results showed that most of the treatments are not significantly different from the control groups. Only treatment no. 3 was a little bit different from the others. but not Significantly different. It seems to us that the difference between the results in the three regions was caused by certain conditions like, the nature of the soil the degres of moisture and hours of sunshine, but we are not sure of that. As a conclusion, we can say that antibiotic 'P' has a good effect on potatoes, but in most investigations a rather high concentration of 'P' was required in formulations.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.436-447
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• 2004

Wetland plants have evolved specialized adaptations to survive in the low-oxygen conditions associated with prolonged flooding. The development of internal gas space by means of aerenchyma is crucial for wetland plants to transport $O_2$ from the atmosphere into the roots and rhizome. The formation of tissue with high porosity depends on the species and environmental condition, which can control the depth of root penetration and the duration of root tolerance in the flooded sediments. The oxygen in the internal gas space of plants can be delivered from the atmosphere to the root and rhizome by both passive molecular diffusion and convective throughflow. The release of $O_2$ from the roots supplies oxygen demand for root respiration, microbial respiration, and chemical oxidation processes and stimulates aerobic decomposition of organic matter. Another essential mechanism of wetland plants is downward water movement across the root zone induced by water uptake. Natural and constructed wetlands sediments have low hydraulic conductivity due to the relatively fine particle sizes in the litter layer and, therefore, negligible water movement. Under such condition, the water uptake by wetland plants creates a water potential difference in the rhizosphere which acts as a driving force to draw water and dissolved solutes into the sediments. A large number of anatomical, morphological and physiological studies have been conducted to investigate the specialized adaptations of wetland plants that enable them to tolerate water saturated environment and to support their biochemical activities. Despite this, there is little knowledge regarding how the combined effects of wetland plants influence the biogeochemistry of wetland sediments. A further investigation of how the Presence of plants and their growth cycle affects the biogeochemistry of sediments will be of particular importance to understand the role of wetland in the ecological environment.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.12 no.2
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• pp.256-262
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• 2001

Objective：The enlargement of the lateral ventricle is well established finding in adult-onset schizophrenia, but in the patients with early-onset psychotic disorder(EOPD) is still controversal. To identify structural abnormalities of the lateral ventricle in patients with EOPD and difference of the brain developmental course in EOPD group, planimetrical assessment of the lateral ventricle was conducted by means of retrospective quantitative neuroimaging. Methods：The brain MR images of 14 patients with EOPD(mean age $14.0{\pm}2.1$ years) who met the DSM-III-R diagnostic criteria for schizophrenia and bipolar disorder and 24 control subjects with simple headache(mean age $10.0{\pm}2.1$ years) were collected. Single best view for the lateral ventricle, one axial slice was selected for analysis. MR images were redigitalized with flatbed scanner and data were analyzed with NIH IMAGE software. Results：In the patients with EOPD, there were significant correlations between aging and lateral ventricular sizes and between aging and ventricular brain ratio(VBR). The statistical significance of normal asymmetry of the lateral ventricle was not observed for the EOPD group. The EOPD group had larger lateral ventricular sizes and VBR than control group, but these results were not statistically significant. Conclusion：These findings suggest that the brain abnormalities in patients with EOPD progress from the earlier course of the disorders and the course of brain development in EOPD group is different from control group.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.14 no.1
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• pp.67-73
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• 2011

Purpose: Recently, the incidence of acute hepatitis A has increased nationwide and is related to a low rate of IgG anti-HAV production. To establish effective measures for preventing hepatitis A virus infection, an epidemiologic study on the seroprevalence of anti-HAV is needed. Thus, we investigated the seroprevalence of IgG anti-HAV in children living in Gwangju and Jeonnam. Methods: IgG anti-HAV levels were measured in a total of 1,435 patients who visited Chosun University Hospital between January 2009 and December 2009. Results: The overall seropositve rate was 40.8% (586/1,435). The seropositive rates were 41% among children under the age of 1 year, 49.9% for children 1~5 years old, 51.1% among individuals 5~10 years old, 12.9% for individuals 10~15 years old, and 8.2% for subjects over 15 years old. There was no significant difference between genders in any group. The seropositive rates in Gwangju and Jeonnam were 57.3% and 32.9% for children under the age of 1 year, 52.5% and 44.3% for children 1~5 years old, 60.2% and 33.9% among children 5~10 years old, 14.1% and 9.7% for children 10~15 years old, and 10.8% and 4.2% for individuals over 15 years old. Conclusion: The results demonstrated the low rates of IgG anti-HAV, particularly among subjects over 10 years old, which suggests the possibility of increasing clinical HAV infection rates among adults in the near future. We should actively prevent the spread of hepatitis A virus. Vaccination is the most effective means of preventing hepatitis A virus transmission among persons at risk for infection. Hepatitis A vaccination is recommended for children who have low IgG anti-HAV seropositive rates.

• Journal of Preventive Medicine and Public Health
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• v.20 no.2 s.22
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• pp.228-235
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• 1987

The objective of this study is to examine the correlation between the toluene concentration in the work environment of organic solvents and the concentration of hippuric acid in urine of workers exposed toluene, and to acquire the fundamental materials of workers' health care and to assist the assessment of the biological permisible exposure limit. The control groups are 72 workers who had never been exposed to toluene and the case groups are 101 workers who had been exposed to toluene. This study was conducted to examine the correlation between the concentration of toluene in work environment and workers' hippuric acid concentration, to investigate the complaint difference of subjective symptoms by means of questionaire, between the case groups and control groups. The results and conclusions are as fellows: 1) The highest mean concentration of toluene in the air is $544.13{\pm}7.75ppm$ in the Printing Department of mixing organic solvents. The concentrations of the others are $463.27{\pm}5.24ppm$ in Department of mixture for organic solvents, and $393.56{\pm}45.69ppm$ in the Printing Department(1), and $248.38{\pm}45.16ppm$ in the Printing Department(2), and $159.38{\pm}18.51ppm$ in the Printing Department(3). 2) The highest mean concentration of hippuric acid in urine is $6034.84{\pm}1298.35mg/l$ in the Printing Department with mixing organic solvents. The concentrations of the others are $4798.44{\pm}784.53mg/l$ in Department of mixture of organic solvents, and $2883.06{\pm}701.90mg/l$ in the Printing Department(1), and $1449.98{\pm}905.19mg/l$ in the Printing Department(2), and $598.52{\pm}299.43mg/l$ in the Printing Department(3). 3) As the toluene concentration in the work environment becomes higher, the concentration of hippuric acid in urine also becomes higher. It is found that the coefficient of correlation between toluene concentration and the concentration of hippuric acid are positive (r=0.868, Y=7.18X+349.57) 4) It is found that the case groups complain of much more subjective symptoms than the control groups.

• Korean Security Journal
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• no.11
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• pp.21-36
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• 2006

This study aims to grasp the general conditions regarding university students in security related majors in Korea. Followings will be covered here: what motivated them to choose those majors, how much are they satisfied with major curriculum course after matriculation, whether they got jobs through the education, what is their consciousness on their majors, jobs, and courses like, and what effects their job preference. And this study also aims at helping the students with their future plans such as admission to a school of higher grade and choosing their job. For this study, we distributed 340 cpoies to the students in security related majors at 4 four-year colleges and 1 two-year college, and collected 298 copies by means of quota sampling method. For collected questionnaires, we used individual T-test verification and one-way ANOVA analysis to grasp the situation. Significance standard for the test results was set as p<0.05. Following are the test results. First, the analysis on students' satisfaction rate resulted in male students' average of 2.42, compared to female students' average of 2.10, which shows female students have higher satisfaction rate in choosing their majors than male students. Secondly, The results on analysis of satisfaction rate on their curriculums, classes, and majors show that students in security-related majors showed different satisfaction rate and different averages according to their sex and the year of the college. The study indicates that males have higher satisfaction rate on curriculum than females, with male students' average of 2.63 and female students' average 2.88. According to the year of the college, there was a significant difference statistically, Statistics show that students at two-year college have higher satisfaction rate than those at four-year college, with two-year college students' average of 2.48 and four-year college students' of 2.74. students have the average of 3.56. The higher year they were in, the more improvement the curriculum required. When it comes to convenience offer for employment, male students expected more from school than female students, with males' average of 2.74 and females' average of 4.07. Male students marked higher than female students in the extent of job information offer, with males' average of 2.96 and females' average of 2.59. Fourthly, when students in security-related majors were surveyed on their consciousness of their future plans such as getting jibs, two-year college students had more certificates of qualification for employment than four-year college students. What they do preponderantly in preparation for employment was studying foreign languages, which took up 40.4%. And when they were asked on their confidence for employment, positive answers were far more than negative ones with the percentage of 39.6%, while negative took up just 14.0%. Fifthly, when it come to the students in security-related students' job preferences, 49.2% preferred safe job conditions in public security area and 34% preferred private guard or private security organizations. And in the public security area, the highest percentage of 28.6 preferred to work in presidential security service. In the area of private security, 21.2% showed interests in private guard and private security organizations.

• Journal of the Korean earth science society
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• v.23 no.6
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• pp.494-506
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• 2002

The Korean Standard-Time (KST) in practice is about 30 minutes earlier than Korea’s solar-time. Suitability of tile KST is analysed by whether it is suitable for the society in general and for the mental and physical health of the Korean people. About 56% of the countries in the world use single standard-time coincident, 18% are 30 minutes earlier, and 21% are an hour or more earlier than their solar-times, respectively, and only 5% have standard-times 30 minutes later than their solar-time. This means adoption of the standard-time earlier than the solar-time is rather acceptable in most countries without any harm to the mental and physical health of their people. Because Korea is located on the western margin of the I-time zone (which is used standard longitude of 135$^{\circ}$E and is used as KST), KST is about 30 minutes earlier than Korea’s solar-time. This situation does not seem to affect adversely the physical, physiological or psychological activities of the people of Korea. It also helps in effective use of the daily time schedule throughout the year, moreover it diminishes the necessity of the summer-time system in the Korea. If H$^{\ast}$-time of the longitude of 127.5$^{\circ}$E that passes through middle of the Korean peninsular is used as KST, non-integer time difference from UTC is inevitable which may be of great inconvenience, and also the introduction of a summer-time system like most countries in high latitude, using their standard-time coincidentally with or even earlier than their solar time, will become essential.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.4
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• pp.528-543
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• 2005

Statement of problem: Repeated delivery and removal of abutment cause some changes such as wear, scratch or defect of hexagonal structure. It may increase the value of rotational freedom(RF) between hexagonal structures. Purpose: The purpose of this study was to evaluate surface changes and rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment after repeated delivery and removal under SEM and toolmaker's microscope. Materials and methods: Implant systems used for this study were 3i and Avana. Seven pail's of implant fixture, abutment and abutment screws for each system were selected and all fixtures were perpendicularly mounted in liquid unsaturated polyesther with dental surveyor. Each one was embedded beneath the platform of fixture. Surfaces of hexagonal structure before repeated closing and opening of abutment were observed using SEM and rotational freedom was measured by using toolmaker's microscope. Each abutment was secured to the implant future by each abutment screw with recommended torque value using a digital torque controller and was repeatedly delivered and removed by 20 times respectively. After experiment, evaluation for the change of hexagonal structures and measurement of rotational freedom were performed. Result : The results were as follows; 1. Wear of contact area between implant fixture and abutment was considerable in both 3i and Avana system. Scratches and defects were frequently observed at the line-angle of hexagonal structures of implant fixture and abutment. 2. In the SEM view of the external hexagon of implant fixture, the point-angle areas at the corner edge of hexagon were severely worn out in both systems. It was more notable in the case of 3i systems than in that of Avana systems. 3. In the SEM view of the internal hexagon of abutment, Gingi-Hue abutment of 3i systems showed severe wear in micro-stop contacts that were machined into the corners to prevent rotation and cemented abutment of Avana systems showed wear in both surface area adjacent to the corner mating with external hexagon of implant fixture. 4 The mean values of rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment were 0.48$\pm$0.04$^{\circ}$ in pre-tested 3i systems and 1.18$\pm$0.25$^{\circ}$ after test, and 1.80$\pm$0.04$^{\circ}$ in pre-tested Avana systems and 2.61$\pm$0.16$^{\circ}$ after test. 5. Changes of rotational freedom after test shouted statistical)y a significant increase in both 3i and Avana systems(P<0.05, paired t-test). 6. Statistically, there was no significant difference between amount of increase in the rotational freedom of 3i systems and amount of increase in that of Avana ones(P>0.05, unpaired t-test). Conclusion: Conclusively, it was considered that repeated delivery and remove of abutment by 20 times would not have influence on screw joint stability. However, it caused statistically the significant change of rotational freedom in tested systems. Therefore, it is suggested that repeated delivery and remove of abutment should be minimal as possible as it could be and be done carefully Additionally, it is suggested that the means or treatment to prevent the wear of mating components should be devised.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.3
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• pp.488-495
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• 2001

Treatment of class II malocclusions require distalization of maxillary molars into class I relationship. Intraarch distal molar movement techniques have recently assumed an important role in young patients. In this study, the dental and skeletal effects of the pendulum appliance were evaluated by means of cephalometric radiographs. The samples were consisted of 19 patients: 11 females and 8 males, mean age $11.68{\pm}1.52$ years. Measurements were obtained from cephalometric prior to and the day of removal of the pendulum appliance. Treatment changes were analyzed. The following results were obtain. 1. The pendulum appliance produced $2.94{\pm}1.54mm$ distal molar movement with a mean intrusion of $1.17{\pm}0.97mm$, mean period $18.13{\pm}7.95$ weeks. 2. The anchor tooth was $1.34{\pm}1.40mm$ forward movement and $0.48{\pm}0.99mm$ extrusion, and labial tilting of incisors. 3. The angle between palatal plane and mandibular plane increased significantly. 4. There was no significant difference in according to 2nd molar position. 5. Total movement was consisted of 74% distal movement of 1st molar and 26% forward movement of the anchor tooth.