• International Journal of Highway Engineering
• /
• v.6 no.3 s.21
• /
• pp.1-7
• /
• 2004

Roads, like bikeways, parkways and walks, are to be just capable of supporting light traffic and traveling public, but they are required to be human friendly and environmental-oriented. Lately soil-solidifier mixture, a kind of soil-cement, has developed and has been applied to the recycling and environment-oriented pavement as the surfacing material. Soil-solidifier pavement structure has been designed by only experience. To design this pavement mechanically, it is necessary to find out basic engineering properties of soil-solidifier mixture. This study focuses on finding out mechanical characteristics of the mixture according to mixture proportions and aging. Test molds with various mixture proportions are made, and then unconfined strength tests are performed for test molds with aging of the mixture. As the result of this study, it is found that the strength of the mixture increases with amount of cement and that maximum strength is achieved at 6%$\sim$8% of the ratio of solidifier and water. The strength increase rapidly until 14 days, after then slowly. After 28 days the strength of the mixture approaches to the constant value. The heat of hydration during curing of the mixture is measured no significantly. It also shows that temperature characteristics of the mixture is similar to that of soil. Since this mixture is mixed with soil and is able to improve engineering problems in pavement due to temperature, this mixture is expected to use effectively in the environment-oriented pavement for light traffic.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2000.09a
• /
• pp.201-210
• /
• 2000

Rock bridge in rock masses can be considered as one of several types of opening-mode fractures, and also it has been known to have a great influence on the stability of structures in rock mats. In the beginning of researching a rock bridge it used to be studied only in characteristics of its behavior, as considering resistance of material itself. However the distribution pattern of rock bridges, which can affect the stability of rock structures, is currently researched with a fracture mechanical approach in numerical studies. For investigating the effect of rock bridges on the development pattern of hydraulic fractures, the author analyzed numerically the stress state transition in rock bridges and their phenomena with a different pattern of the rock bridge distributons. From the numerical studies, a two-crack configuration could be defined to be representative of the most critical conditions for rock bridges, only when cracks are systematic and same in their length and angle. Moreover, coalescence stresses and onset of propagation stresses could be known to increase with decreasing s/L ratio or increasing d/L ratio. The effect of pre-existing crack on hydraulic fracturing was studied also in numerical models. Different to the simple hydraulic fracturing modeling in which the fractures propagated exactly parallel to the maximum remote stress, the hydraulic fractures with pre-existing cracks dial not propagate parallel to the maximum remote stress direction. These are representative of the tendency to change the hydraulic fractures direction because of the existence of pre-existing crack. Therefore s/L, d/L ratios will be identical as a function effective on hydraulic fractures propagation, that is, the $K_{I}$ vague increase with decreasing s/L ratio or increasing d/L ratio and its magnification from onset to propagation increases with decreasing s/L ratio. The scanline is a commonly used method to estimate the fracture distribution on outcrops. The data obtained from the scanline method can be applied to the evaluation of stress field in rock mass.s.

• Journal of radiological science and technology
• /
• v.31 no.3
• /
• pp.239-247
• /
• 2008

In order to study the occurrence of symptoms of musculoskeletal disorders of radio-technologists employed at metropolitan general hospitals and the factors that influence such occurrence, standardized questionnaire by NIOSH that was modified and supplemented to be suitable for conditions in Korea was used. Answers collected from 143 radio-technologists in two weeks from June 13, 2007 were analyzed and the results are as follows. Factor that influence symptoms of musculoskeletal disorders by area were analyzed through multiple logistic regression analysis and the results found that in the neck area, risk increased as the burdening work category 2(Korea ministry of labor)(OR=3.94) and burdening work category 9(Korea ministry of labor)(OR=4.72) increased. In the shoulder region, risk increased as burdening work category 2(Korea ministry of labor)(OR=5.36), burdening work category 7(Korea ministry of labor)(OR=3.90), and burdening work category 9 (Korea ministry of labor)(OR=5.76) increased. In the arm/hand/wrist regions, risk increased as burdening work category 2 (Korea ministry of labor) (OR=6.91), and burdening work category 9 (Korea ministry of labor)(OR=3.76) increased. In the lower back region, risk increased as burdening work category 2 (Korea ministry of labor) (OR=3.06), and burdening work category 8 (Korea ministry of labor)(OR=8.14) increased. In the leg/knees/foot regions, risk increased as burdening work category 2 (Korea ministry of labor) (OR=3.63), and burdening work category 9 (Korea ministry of labor)(OR=2.96) increased. Conclusively, in factors that influence musculoskeletal disorder symptoms in radio-technologists, influence of subjective health conditions, total work experience, experience in current division, and burdening work category 2, 7, 8, and 9 (Korea ministry of labor) were most significant. Therefore, for preventive management, in addition to ergonomic and educational intervention for correcting improper posture during work, efforts for break time adjustment and stress reduction is needed, and encouragement and support for regular exercise is needed.

• Journal of radiological science and technology
• /
• v.32 no.4
• /
• pp.437-444
• /
• 2009

Ultrasonography has been used as a basic examination of a medical check up for prevention and diagnostics of diseases. Even the person who has no particular subjective symptoms can have a variety of diseases. Especially fatty liver is found in many cases. In this study, we tested 3582 persons who are in between the ages of 15 to 81 and observed that 1390 persons had fatty liver while 2192 persons are normal. We classified the grade of fatty liver and compared their life styles with the results of liver function test and BMI. The results are as follows. Ratio of the subjects who had a fatty liver is 38.8%. Male and female ratio was 46.2% and 24.2%. On the correlation among the fatty liver, the body mass index and the body fat%, the average value of body mass index and body fat% were significantly higher in the group of the fatty liver than in those of the normal liver. The influence of the related factor and the correlation on the fatty liver was shown that it was more related with the order of age, body mass index, triglyceride, ALT, body fat%, sex, HDL-Cholesterol, LDL-Cholesterol, and GGT. The result of the ultrasonography carried out for the purpose of regular health check up indicates that even the 38.8% of those who was diagnosed as normal condition could have the fatty liver and have possibility of other diseases. Therefore, if there are any troubles related to liver function and lipid through hematologic examination or when practicing follow-up study with ultrasonography concerning the correlation relation between the body fat% and dietary preference, alcohol consumption and exercise, the ultrasonography is definitely useful for prevention and treatment of diseases.

• Journal of radiological science and technology
• /
• v.32 no.4
• /
• pp.361-370
• /
• 2009

The image quality management of bone mineral density is the responsibility and duty of radiologists who carry out examinations. However, inaccurate conclusions due to lack of understanding and ignorance regarding the methodology of image quality management can be a fatal error to the patient. Therefore, objective of this paper is to understand proper image quality management and enumerate methods for examiners and patients, thereby ensuring the reliability of bone mineral density exams. The accuracy and precision of bone mineral density measurements must be at the highest level so that actual biological changes can be detected with even slight changes in bone mineral density. Accuracy and precision should be continuously preserved for image quality of machines. Those factors will contribute to ensure the reliability in bone mineral density exams. Proper equipment management or control methods are set with correcting equipment each morning and after image quality management, a phantom, recommended from the manufacturer, is used for ten to twenty-five measurements in search of a mean value with a permissible range of ${\pm}1.5%$ set as standard. There needs to be daily measurement inspections on the phantom or at least inspections three times a week in order to confirm the existence or nonexistence of changes in values in actual bone mineral density. in addition, bone mineral density measurements were evaluated and recorded following the rules of Shewhart control chart. This type of management has to be conducted for the installation and movement of equipment. For the management methods of inspectors, evaluation of the measurement precision was conducted by testing the reproducibility of the exact same figures without any real biological changes occurring during reinspection. Bone mineral density inspection was applied as the measurement method for patients either taking two measurements thirty times or three measurements fifteen times. An important point when taking measurements was after a measurement whether it was the second or third examination, it was required to descend from the table and then reascend. With a 95% confidence level, the precision error produced from the measurement bone mineral figures came to 2.77 times the minimum of the biological bone mineral density change. The value produced can be stated as the least significant change (LSC) and in the case the value is greater, it can be stated as a section of genuine biological change. From the initial inspection to equipment moving and shifter, management must be carried out and continued in order to achieve the effects. The enforcement of proper quality control of radiologists performing bone mineral density inspections which brings about the durability extensions of equipment and accurate results of calculations will help the assurance of reliable inspections.

• Journal of radiological science and technology
• /
• v.32 no.4
• /
• pp.381-391
• /
• 2009

Purposes : The purpose of this study was to analyze factors that could affect health of radiological technologists, which is useful for health care and development of programs for health promotion. Methods : Subjects were 234 of radiological technologists who work in general hospitals. Some questionnaires were made about perceptions of health condition and promotional behavior of health for this study. The questionnaires of health perception were 20 items that consist of the present condition of health, health concern and sensitivity. The reliability was sufficient(Cronbach's $\alpha=0.79$). The other questionnaires about health promotion behavior were 47 items that consist of self-realization, health responsibility, exercise, nutrition, personal relationships, and stress management. The results turned out to bewas sufficient (Cronbach's $\alpha=0.93$). Every data was treated statistically, comparison of average(t-test, ANOVA), correlation, and multiple regression. Results : Related factors to health promotion behavior were age, marriage, salary, class of one's position, career, employment, and religion, in general features. In health life habit, related factors were smoke and exercise. Results of health promotion behavior was 2.90 of mean score, 0.37 of standard deviation. Correlations between factors of health perception and health promotion behavior was positive(p<0.01). Health promotion behavior were affected by sensitivity, presents condition of health, exercise, smoke, career. Sensitivity was the most affectable variable, which means that promotional behavior score became higher and higher as the score of sensitivity and present condition were increased. In addition, persons who exercise regularly, had been smoked, and has higher career showed higher score of promotional behavior. Conclusion : Radiological technologists have to keep their health, trying not to infected by a disease. Most of all, no smoking and regular exercise are the most important thing to all of members.

• Journal of radiological science and technology
• /
• v.32 no.4
• /
• pp.461-469
• /
• 2009

To predict the tumor grading, various imaging modalities have been applied clinically. This study determines clinical usefulness of perfusion MRI, using relative cerebral blood volume in grading of the gliomas. We did a retrospective review of 17 patients (mean age, 57.5 years; 11 male, 6 female) who underwent perfusion MR and conventional MRI, and then correlated pathologically after operation. Statistical analysis of regional cerebral blood volume and relative cerebral blood volume(rCBV) was performed by using softwares such as PAT by SIEMENS and Xmap ver 2.0 developed by ourselves. Six patients out of 13 were low-grade gliomas while eleven patients were the high-grade gliomas. Mean relative CBV (m_rCBV/white matter) in the low-grade gliomas was 1.62, and mean relative CBV(m_rCBV/cortex) was 0.12. In the high-grade gliomas, mean relative CBV(m_rCBV/white matter) and mean relative CBV(m_rCBV/cortex) were 33.53 and 0.96. Mean relative CBV of gliomas were elevated with a statistical difference(P<.05), compared with contralateral white matter(P=.019) or cortex(P=.025). Furthermore mean relative CBV(m_rCBV/white matter) was much higher than mean relative CBV(m_rCBV/cortex). Perfusion MRI using regional cerebral blood volume and rCBV is very useful imaging modality for grading the glioma.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.16 no.2
• /
• pp.49-56
• /
• 2012

Purpose : Gated myocardial perfusion SPECT provides not only myocardial perfusion status, but various functional parameters of left ventricle (LV). The purpose of this study was to analyze ejection fraction (EF) for correlation and difference between $^{201}Tl$ gated myocardial perfusion SPECT and echocardiography depending on extent of perfusion defect, gender and LV volumes. Materials and Methods : From April 2011 to May 2012, we analyzed 291 patients (male:female =165:126; mean: $64.6{\pm}10.8$ years) who were examined both $^{201}Tl$ gated myocardial perfusion SPECT and echocardiography at less than 7 days apart in our hospital. 101 patients showed perfusion defect and the rest of the people without any defect. We applied automatic analysis (Quantitative gated SPECT, QGS), and calculated EF, End-diastolic volume (EDV) and End-systolic volume (ESV) from Stress (G-Stress) and Rest (G-Rest) studies. And we analyzed the correlation and difference for EF between $^{201}Tl$ gated SPECT and echocardiography. Results : The correlation of LVEF among G-Stress, G-Rest and echocardiography was quite a good (G-Stress vs. G-Rest: r=0.909, G-Stress vs. echocardiography: r=0.833, G-Rest vs. echocardiography: r=0.825). And there were significant differences in EDV, ESV and EF in total patients (p<0.01). The normal group showed significant difference in EF (p<0.01) and the group with perfusion defect also demonstrated significant difference (a group with reversible defect: p<0.01, fixed defect: p<0.01) depending on extent of perfusion defect. We analyzed difference in normal group by gender. In normal group, there was no significant difference (p>0.05) in EF from men. However, there was a significant difference (p<0.01) from women. When we classified two groups by average size of EDV in Korean women, there was no significant difference in a group of above average size of EDV (p>0.05). Conclusion : When compared among Stress and Rest of $^{201}Tl$ gated SPECT and echocardiography, we confirmed that there was a good correlation for LVEF. But there were significant differences among three studies. And extent of perfusion defect, gender and LV volumes are independent determinants of the accuracy of LVEF. So, it is hard to compare and interchange quantitative indices among modalities. We should take additional researches to prove results of our study.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.16 no.2
• /
• pp.62-67
• /
• 2012

Purpose : At this time, the sentinel lymph node mapping using radioisotope and blue dye is preceded for breast cancer patient's sentinel lymph node biopsy. But all patients were applied the same protocol without consideration of physical specific character like the breast sizes and body mass indexes. The purpose of this study is search the optimized scan time in breast sentinel lymphangiography by observing how much the body mass index and breast size influence speed of lymphatic flow. Materials and Methods : The Object of this study was 100 breast cancer patients(Female, 100 persons, average age $50.34{\pm}10.26$ years old)at Severance hospital from October 2011 to December 2011. They were scanned breast sentinel lymphangiography before operation. This study was performed on Forte dual heads gamma camera (Philips Medical Systems, Nederland B.V.). All patients were intra-dermal injected $^{99m}Tc$-Phytate 18.5 MBq, 0.5 ml. For 80 patients, we have scanned without limitation of scan time until the lymphatic flow from the lymph node since injection. We measured how long the lymphatic flow time between departures from injects site and arrival to lymph node using stopwatch. After we calculated patient's Body mass Index and classified as 4 groups. And we measured patient's breast size and classified 3 groups. The modified breast lymphangiography that changing scan time according to comparison study's result was performed on 20 patients and was estimated. Results : The mean scan time as breast size was A group 2.48 minutes, B group 7.69 minutes, C group 10.43 minutes. The mean scan time as body mass index was under weight 1.35 minutes, normal weight 2.56 minutes, slightly over 5.62 minutes, over weighted 5.62 minutes. The success rate of modified breast lymphangiography was 85%. Conclusion : As the Body mass index became higher and breast size became bigger, the total scan time is increased. Based on the obtained information, we designed modified breast lymphangiography protocol. At the cases applying that protocol, most of sentinel lymph nodes were visualized as lymphatic pool. In conclusion, we found that the more success rate in modified protocol considering physical individuality than study carrying out in the same protocol.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.14 no.1
• /
• pp.61-66
• /
• 2010

Purpose: Recently, Department of Nuclear Medicine have an interest in Video Display Terminals (VDT) syndrome including musculoskeletal disorders, ophthalmologic disorders, trouble of electromagnetic waves and stress disorders occur to VDT workers as the growing number of users and rapid pace of service period supply in large amount. This study research on the actual condition for VDT syndrome in Nuclear Medicine, Seoul National University Hospital (SNUH), discover the problem and draw a plan of upcoming improvement. The aim of this study establish awareness about VDT syndrome and is to prevent for it in the long run. Materials and Methods: Department of Nuclear Medicine, SNUH is composed Principle part, Pediatric part and PET center. We estimated risk factors visit in each part directly. Estimation method use "Check list for VDT work" of Wonjin working environment health laboratory and check list is condition of VDT work, condition of work tables, condition of chairs, condition of keyboards, condition of monitors, working position, character of health management and other working environment. Analysis result is verified in Department of Occupational and Environment, Hallym University Sacred Heard Hospital. Results: As a result of analysis, VDT condition of Department of Nuclear Medicine, SNUH is rule good. In case of work tables, recent of things are suitable to users upon the ergonomical planning, but 15% of existing work tables are below the standard value. In case of chairs are suitable, but 5% of theirs lost optimum capacity become superannuated. The keyboards are suitable for 98% of standard value. In case of monitors, angle control of screen is possible of all, but positioning control is impossible for 38%. In case of working position, 10% is fixed positioning for long time and some of the items researched unsuitable things for standard. At health management point, needed capable of improvement. Also, other working condition as lighting, temperature, noise and ventilation, discovered the problem, but is sufficient to advice value. Conclusion: VDT syndrome is occurrences of possibility continuously, come economical expensive about improvement, is inherent in various causes and originate without your knowledge. So, there is need systematic management system. In Nuclear Medicine, VDT syndrome make it better that constant interest and effort as improvement of ergonomical working environment, improvement of working procedure, regular exercise and steady stretching, and can be prevented fairly. This promote physical and mental condition of worker in top form in comfortable working environment, so this is judged by enlargement of operations efficiency and rising of satisfaction ratings of the inside client.