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

• Korean Journal of Health Education and Promotion
• /
• v.21 no.2
• /
• pp.17-32
• /
• 2004

The purpose of this study was to evaluate the patterns of stresses arising from various life styles and their related sociodemographic factors in urban residents. The subjects were recruited from the population of two ‘Dong’s (administrative blocks) representative of Daejeon city through stratified cluster random sampling during the period ranging from June I st to Aug. 31 st, 2003. Self-administered questionnaires, including items asking about subjects' sociodemographic characteristics, daily life styles, measurement of stresses by General Health Questionnaire (Goldberg, 1978), were delivered to 396 residents and their responses were analyzed with the following results. 1. Based on the discriminant scores of HPI, 46.7％ of the subjects were found to have less than 4 points (poor life style), whereas 53.3％ had points higher than 5 (good life style). Higher than 5 points were scored more frequently in females than in the male, in the age group of 40's - 60's than the 30's, in the group with spouse than without, in the group with both spouse and offsprings than without, and in the group owning a house than not. 2. Based on the degree of stress, 17.7％ of the subjects were determined to be healthy, 74.5％ were potentially under stress, and 7.8％ were at higher risk of stress. The proportion of healthy individuals were significantly higher in the male, advanced aged group(40's and 60's), the group with higher education years( over highschool), with higher monthly income over two million Won, and with spouse, than their respective counterparts. On the other hand the proportion of the individuals potentially under stress and at higher risk of stress was significantly higher in the female, in the age group of 30's and over 60's, in the group with academic career lower than middle school, with monthly income lower than two million Won, and without spouse. 3. Based on the relation of HPI with degree of stresses, subjects with HPI scores lower than 4 had increased rate of falling into the groups under potential stress and at higher risk of stress, while on the other hand those with over 5 points were found to be healthy in light of stress. 4. Based on the specific relation of each item of HPI with degree of stress, the proportion of healthy individuals was higher in the groups who take appropriate hours of sleep(7-8hours), who take breakfasts everyday, who take physical exercises everyday, who don't smoke, who don't drink alcohol, who take snacks everyday, who are overweight and obese, whereas the proportion of the group under potential stress and at higher risk of stress was higher in their comparable counterparts. 5. The relation of mean scores of HPI with stress scores in both male and female subjects showed negative correlation that the higher HPI scores, the lower stress scores. 6. Multivariate regression analysis to reveal the factors influencing the stress of the subjects showed that for men the significant factors were age, education, presence of job or not, exercise, subjective health status, with the explanatory power of 26.3％. For women, they included educational years, presence of spouse or not, job, owning a house or not, sleeping hours, drinking habit, taking snacks, subjective health status, with the explanatory power of 31.8％. The above study results suggests that stresses of urban residents have significant correlation with daily life styles and this correlation is also remarkably distinguished by different age and sex.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.45 no.2
• /
• pp.51-59
• /
• 2017

This study evaluated the drought tolerance of Liriope platyphylla F.T.Wang & T.Tang, Dendranthema zawadskii var. lucidum (Nakai) J.H.Park, Hosta longipes (Franch. & Sav.) Matsum., Sedum sarmentosum Bunge and Zoysia japonica Steud. for an extensive green roof. In order to assess drought tolerance of green roof plants, several criteria were measured such as volumetric water content, leaf and soil moisture potential, chlorophyll a and b, chlorophyll fluorescence, photosynthesis, stomatal conductance, transpiration rate and antioxidants. The results of the drought tolerance measurement of green roof plants focused on the gradually withering of plants from lack of volumetric water content. D. zawadskii was the first to show an initial wilting point, followed by Z. japonica, H. longipes and L. platyphylla in order while S. sarmentosum showed no withering. It was concluded that H. longipes, L. platyphylla and S. sarmentosum were highly drought tolerant plants able to survive over three weeks. Furthermore, chlorophyll a and b were divided into two types: Type I, which kept regular content from the beginning to the middle of the period and suddenly declined, like H. longipes and Z. japonica; and Type II, which showed low content at the beginning, sharply increased at the middle stage and decreased, like D. zawadskii, L. platyphylla and S. sarmentosum. Volumetric water content and the amount of evapotranspiration consistently declined in all plant species. The analysis of chlorophyll fluorescence results that S. sarmentosum, which had relatively high drought tolerance, was the last to decline, while Z. japonica and S. sarmentosum withered after rapid reduction. At first, photosynthesis, stomatal conductance and transpiration rate showed high activity, but they lowered as the plant body closed stomata owing to the decrease in volumetric water content. Measuring antioxidants showed that when drought stress increased, the amount of antioxidants grew as well. However, when high moisture stress was maintained, this compound was continuously consumed. Therefore, the variation of antioxidants was considered possible for use as one of the indicators of drought tolerance evaluation.

• The Korean Journal of Community Living Science
• /
• v.17 no.4
• /
• pp.151-161
• /
• 2006

This study was made to find out how health practice affect on nutrition status of the college freshmen in male and female. 400 freshmen students in 4year colleges were surveyed. Questionnaire and blood analysis were made. The contents of questionnaire contained general characteristics, health practice behavior, and food intake. The physical measurement included height, weight and blood pressure. The questions for health practice were about drinking, smoking, BMI, skipping breakfast and sleeping. Nutrient intake was expressed by DDS(Dietary Diversity Score by 5 food groups) and DVS (Dietary Variety Score) and 24-hrs recall method was used to find out the quantity of daily food intake. EAR% was calculated and NAR and MAR were produced. The results are as follows: 1) BMI was $22.77kg/m^2$ for males and $20.42kg/m^2$ for females. The ratio maintaining normal weight indicated by BMI of 18.5-23 was higher(p<0.001) for female students(63.2%) than males(56.5%). The ratio of overweight with over $23kg/m^2$ of BMI was 28.5% for males and 8.8% for females(p<0.001). 2)The ratio of drinking students was 59.4% for males and 40.6% for female(p<0.001). And the ratio of smoking students was 95.2% for males and 4.8% for females(p<0.001). 3) The ratio of poor health practice group was 35.7% for males and 25.5% for females, and that of excellent one was 25.4% for males and 33.1% for females(p<0.05). 4) In NAR, the lowest ratio was observed for the intake of Ca, Fe, Vitamin C and Vitamin $B_2$. The intake of Fe, Vitamin $B_2$ and phosphorus were different significantly according to sexuality. For Fe, female students showed lower level than male students(p<0.001). For Vitamin $B_2$, and phosphorus female students showed higher level(p<0.001). 5) In MAR, there was no difference according to sexuality in almost all of the ingredients. 6) For energy intake, male and female students showed 59% and 66% of EAR and it was insufficient for them. 7) For protein, more than 100% was obtained. The lowest ratio was observed for the intake of vitamin C 50.8%, Ca 53.6% and Fe 65.1% of EAR were obtained. The lowest intake ratio and for the intake of Fe female students obtained just 37.5% of EAR showing high risk of anemia. The intake of energy(p<0.001), phosphorus(p<0.01), niacin(p<0.05), Fe(p<0.001), and Vitamin $B_2$ (p<0.001) were different significantly according to sexuality. For Fe, female students showed lower level than male students(p<0.001). For energy, phosphorus, niacin, and Vitamin $B_2$ female students showed higher level(p<0.001) than male students. 8) For blood pressure, male students showed normal level of 120.7/79.1 mmHg, however, female students showed 114.5/75.4 mmHg lower than male (p<0.001). 9). In blood, for hemoglobin female students showed significantly lower level than that of male(p<0.001). T-Cholesterol and HDL-Cholesterol female students showed higher level than males (p<0.001), And for triglyceride male students showed higher level than females(p<0.001). Ca and Fe female students showed lower level (p<0.001).

• Journal of Chest Surgery
• /
• v.38 no.2 s.247
• /
• pp.101-109
• /
• 2005

Background: In sudden cardiac arrest, the effective maintenance of coronary artery blood flow is of paramount importance for myocardial preservation as well as cardiac recovery and patient survival. The purpose of this study was to directly compare the effects of pulsatile and non-pulsatile circulation to coronary artery flow and myocardial preservation in cardiac arrest condition. Material and Method: A cardiopulmonary bypass circuit was constructed in a ventricular fibrillation model using fourteen Yorkshire swine weighing $25\~35$ kg each. The animals were randomly assigned to group I (n=7, non-pulsatile centrifugal pump) or group II (n=7, pulsatile T-PLS pump). Extra-corporeal circulation was maintained for two hours at a pump flow of 2 L/min. The left anterior descending coronary artery flow was measured with an ultrasonic coronary artery flow measurement system at baseline (before bypass) and at every 20 minutes after bypass. Serologic parameters were collected simultaneously at baseline, 1 hour, and 2 hours after bypass in the coronary sinus venous blood. The Mann-Whitney U test of STATISTICA 6.0 was used to determine intergroup significances using a p value of < 0.05. Result: The resistance index of the coronary artery was lower in group II and the difference was significant at 40 min, 80 min, 100 min and 120 min (p < 0.05). The mean velocity of the coronary artery was higher in group II throughout the study, and the difference was significant from 20 min after starting the pump (p < 0.05). The coronary artery blood flow was higher in group II throughout the study, and the difference was significant from 40 min to 120 min (p < 0.05) except at 80 min. Serologic parameters showed no differences between the groups at 1 hour and 2 hours after bypass in the coronary sinus blood. Conclusion: In cardiac arrest condition, pulsatile extracorporeal circulation provides more blood flow, higher flow velocity and less resistance to coronary artery than non-pulsatile circulation.

• Nuclear Engineering and Technology
• /
• v.4 no.3
• /
• pp.214-222
• /
• 1972

In the optic,11 grade LiF crystal, the electron traps corresponding to the thermoluminescence(abbreviated to TL) glow peak develop as irradiation dose is increased. Originally the electron trap of the crystal has two levels but as the dose reaches to the order of 10$^4$rontgen, it attains five levels as observed in the TL glow curves. The five trap depths are determined from the glow peak temperatures for two different heating rates, $\theta$=6.6$^{\circ}C$/sec and 3.4$^{\circ}C$/sec. The electron trap depths have the following values E$_1$=0.79 eV, E$_2$=0.93 eV, E$_3$=1.02 eV, E$_4$=1.35 eV, E$_{5}$=1.69eV. The special feature of thermoluminescence of optical grade LiF is that the traps, except E$_1$and E$_2$corresponding to 12$0^{\circ}C$ glow peak and 15$0^{\circ}C$ glow peak for $\theta$=6.6$^{\circ}C$/sec, have severe thermal instability, namely E$_3$, E$_4$and E$_{5}$ levels disappear during bleaching process. These defects in the optical grade LiF crystal seem annealed out during the course of TL measurement. The fresh or long time unused LiF(Mg) crystal shows only two glow peaks at 17$0^{\circ}C$ and 23$0^{\circ}C$ for $\theta$=6.6$^{\circ}C$/sec, but upon sensitization with r-ray irradiation, it converts to the six glow peak state. The four electron traps, E$_1$, E$_2$, E$_3$, and E$_{6}$ created by r-ray irradiation and corresponding to the glow peaks at T=10$0^{\circ}C$ 13$0^{\circ}C$, 15$0^{\circ}C$ and 29$0^{\circ}C$ are stable and not easily annealed out thermally, The sensitization essentially required to LiF(Mg) dosimeter is to give the crystal the stable six levels in the electron trap. In optical grade LiF, the plot between logarithm of total TL output versus logarithm of r-ray dose gives more supra-linear feature than that of LiF(Mg). However, if one takes the height of 12$0^{\circ}C$ glow peak(S=6.6$^{\circ}C$/sec), instead of the total TL output, the curve becomes close to that of LiF(Mg).

• The Korean Journal of Nuclear Medicine Technology
• /
• v.16 no.1
• /
• pp.80-85
• /
• 2012

Purpose: The whole body bone scan is an examination that visualizing physiological change of bones and using bone-congenial radiopharmaceutical. The patients are intravenous injected radiopharmaceutical which labeled with radioactive isotope ($^{99m}Tc$) emitting 140 keV gammarays and scanned after injection. The 3 principles of radiation protection from external exposureare time, distance and shielding. On the 3 principles of radiation protection basis, radiopharmaceutical might just as well be injected rapidly for reducing radiation because it might be the unopened radiation source. However the radiopharmaceuticals are injected into patient directly and there is a limitation of distance control. This study confirmed the change of radiation exposure as change of distance from radiopharmaceutical and observed the change of radiation exposure afte rsetting a shelter for help to control radio-technician's exposure. Materials & methods: For calculate the average of injection time, the trained injector measured the injection time for 50 times and calculated the average (2 minutes). We made a source as filled the 99mTc-HDP 925 MBq 0.2 mL in a 1 mL syringe and measured the radiation exposure from 50 cm,100 cm,150 cm and 200 cm by using Geiger-Mueller counter (FH-40, Thermo Scientific, USA). Then we settled a lead shielding (lead equivalent 6 mm) from the source 25 cm distance and measured the radiation exposure from 50 cm distance. For verify the reproducibility, the measurement was done among 20 times. The correlation between before and after shielding was verified by using SPSS (ver. 18) as paired t-test. Results: The radiation doses according to distance during 2 minutes from the source without shielding were $1.986{\pm}0.052{\mu}$ Sv in 50 cm, $0.515{\pm}0.022{\mu}$ Sv in 100 cm, $0.251{\pm}0.012{\mu}$ Sv in 150 cm, $0.148{\pm}0.006{\mu}$ Sv in 200 cm. After setting the shielding, the radiation dose was $0.035{\pm}0.003{\mu}$ Sv. Therefore, there was a statistical significant difference between the radiation doses with shielding and without shielding ($p$<0.001). Conclusion: Because the great importance of whole body bone scan in the nuclear medicine, we should make an effort to reduce radiation exposure during radiopharmaceutical injections by referring the principles of radiation protection from external exposure. However there is a limitation of distance for direct injection and time for patients having attenuated tubules. We confirmed the reduction of radiation exposure by increasing distance. In case of setting shield from source 25 cm away, we confirmed reducing of radiation exposure. Therefore it would be better for reducing of radiation exposure to using shield during radiopharmaceutical injection.

• Journal of Technology Innovation
• /
• v.11 no.1
• /
• pp.147-176
• /
• 2003

This Paper Presents a new measurement technique to derive the level of BSRC (Basic Science and Research Capacity) index by use of the factor analysis which is extended with the assumption of the standard normal probability distribution of the selected explanatory variables. The new measurement method is used to forecast the gap of Korea's BSRC level compared with those of major OECD countries in terms of time lag and to make their international comparison during the time period of 1981∼1999, based on the assumption that the BSRC progress function of each country takes the form of the logistic curve. The US BSRC index is estimated to be 0.9878 in 1981, 0.9996 in 1990 and 0.99991 in 1999, taking the 1st place. The US BSRC level has been consistently the top among the 16 selected variables, followed by Japan, Germany, France and the United Kingdom, in order. Korea's BSRC is estimated to be 0.2293 in 1981, taking the lowest place among the 16 OECD countries. However, Korea's BSRC indices are estimated to have been increased to 0.3216 (in 1990) and 0.44652 (in 1999) respectively, taking 10th place. Meanwhile, Korea's BSRC level in 1999 (0.44652) is estimated to reach those of the US and Japan in 2233 and 2101, respectively. This means that Korea falls 234 years behind USA and 102 years behind Japan, respectively. Korea is also estimated to lag 34 years behind Germany, 16 years behind France and the UK, 15 years behind Sweden, 11 years behind Canada, 7 years behind Finland, and 5 years behind the Netherlands. For the period of 1981∼1999, the BSRC development speed of the US is estimated to be 0.29700. Its rank is the top among the selected OECD countries, followed by Japan (0.12800), Korea (0.04443), and Germany (0.04029). the US BSRC development speed (0.2970) is estimated to be 2.3 times higher than that of Japan (0.1280), and 6.7 times higher than that of Korea. German BSRC development speed (0.04029) is estimated to be fastest in Europe, but it is 7.4 times slower than that of the US. The estimated BSRC development speeds of Belgium, Finland, Italy, Denmark and the UK stand between 0.01 and 0.02, which are very slow. Particularly, the BSRC development speed of Spain is estimated to be minus 0.0065, staying at the almost same level of BSRC over time (1981 ∼ 1999). Since Korea shows BSRC development speed much slower than those of the US and Japan but relative]y faster than those of other countries, the gaps in BSRC level between Korea and the other countries may get considerably narrower or even Korea will surpass possibly several countries in BSRC level, as time goes by. Korea's BSRC level had taken 10th place till 1993. However, it is estimated to be 6th place in 2010 by catching up the UK, Sweden, Finland and Holland, and 4th place in 2020 by catching up France and Canada. The empirical results are consistent with OECD (2001a)'s computation that Korea had the highest R&D expenditures growth during 1991∼1999 among all OECD countries ; and the value-added of ICT industries in total business sectors value added is 12% in Korea, but only 8% in Japan. And OECD (2001b) observed that Korea, together with the US, Sweden, and Finland, are already the four most knowledge-based countries. Hence, the rank of the knowledge-based country was measured by investment in knowledge which is defined as public and private spending on higher education, expenditures on R&D and investment in software.

• Journal of Biomedical Engineering Research
• /
• v.20 no.6
• /
• pp.515-521
• /
• 1999

Scintillator crystal is an important part and detcrmines performance characteristics of the gamma camera. We investigated the offects of scintillation crystal surface treatment on gamma camera imaging. Nal(TI) and Csl(Tl) scintillators. 20 mm diameter and 10 mm thickness, applied with two different surface treatments, white and black reflcetors, were applied to Nal(Tl) and Csl(Ti). The optical properties of generated scintillation light were evaluated by Monte Carlo simulation method and by actual measurement using a position sensitive photomultiplier tube (PSPMT). We measured sensitivity, energy resolution and spatial resolution of gamma camera with the various scintillators coupled to a PSPMT. In the simulation. Nal(Tl)-white prosented the best sensitivity. In the measurements, the sensitivities and the intrinsic spatial resolutions of Nal(Tl)-white, Nal(Tl)-black. CsI(Tl)-white, CsI(Tl)-black were 2920, 2322, 1754, 1401 cps/$\mu$ci and 5.2, 4.5, 7.0, 6.3 mm FWHM. respectively. Their intrinsic energy resolutions were mesured 12.5, 23.5, 20.5, 33.3% FWHM at 140 keV Tc-99m. In this study, we investigated the offects of a side surface treatment of the scintillator on the gamma camera imaging. Simulation and measurement prescnted similat trends. Based on the results, we concluded that the surface of th NaI(Tl)seintillator must be treated by absorptive materials in order to develop the gamma camera having good spatial resolution.

• Journal of dental hygiene science
• /
• v.9 no.1
• /
• pp.99-108
• /
• 2009

The purpose of this study was to investigate the effect of oral health education practice and schoolteacher's self-efficacy on oral health attitude. The data of 217 dental hygienists was subjected to path analysis using AMOS 16.0. Oral health knowledge, attitude, self-efficacy and oral health education practice of schoolteacher were measurement variables of three path models. The goodness of fitness of Knowledge-Attitude-Practice model and Knowledge-Attitude-Self efficacy -Practice model were acceptable. The regression weights of two models were statistically significant. Oral health education practice of schoolteacher gave impact on oral health attitude by mediation of self-efficacy of schoolteacher. Self-efficacy of schoolteacher was a important determinant of oral health education practice. Oral health attitude and practice were supposed to be mutual determinants of health behavior models.