• Maxillofacial Plastic and Reconstructive Surgery
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• v.23 no.2
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• pp.107-114
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• 2001

Objectives : To compare jaw bone density of young adults (control group) and post-menopausal women(experimental group) in periapical and panoramic film. Materials and Methods : The bone mineral density values of lumbar and femur were measured by dual-energy X-ray absorptiometry(DEXA) and T scores of lumbar were obtained. T scores were classified into 3 group (T<-2.5, $-2.5{\leqq}T<-1$, $-1{\leqq}T$). Radiographic densities of alveolar bones were measured from interdental bones of premolar, molar areas in the maxilla and mandible and expressed into copper step wedge thickness by Scion $Image^{(R)}$ program. We considered these values of step wedge thickness as bone density of alveolar bone. Panorama mandibular index(PMI) was calculated by the method that the height of the inferior cortex of the mandible was divided by the height from the lower border of the mandible to the superior edge of the mental foramen. Bone density of alveolar bone and PMI were analysed statistically. Results : There were significant differences in bone mineral density of lumbar and femoral neck between control and experimental groups. There were also significant differences in bone density of premolar and molar area of jaw between control and experimental groups by MANOVA test. When considered lumbar T variables, there was only difference in interdental bone density of maxillary molar area between control and experimental group, but there was interaction. Interdental bone density of experimental group was appeared higher in $-1{\leqq}T$ group and lower in T<-2.5 group than control group. There was significant difference in PMI between control and experimental groups, but there was also inter action, thus, PMI of experimental group was appeared higher in $-1{\leqq}T$ group and lower in T<-2.5 group than control group. Conclusion : There were significant differences of alveolar density and cortical bone thickness between young men and post-menopausal women in periapical and panoramic film. These differences were dependent on lumbar T.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.3
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• pp.325-340
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• 2008

The purpose of this study was to evaluate the artificial dental plaque by Streptococcus mutans on 4 different implant surfaces. In this study, the specimens were divided into 4 groups according to implant surface treatment. Uncoated implant group(n=5) which has an uncoated, smooth surfaced implant(Osstem, Korea), SLA implant group(n=5) which has an sandblasted large grit and acid-etched surface implant(Bicon, USA). Oxidized implant group(n=5) which has an oxidized surfaced implant (Osstem, Korea), and RBM implant group(n=5) which has resorbable blasting media(RBM) surfaced implant(Osstem, Korea). Acquired pellicle by human saliva and dental plaque by Streptococcus mutans were made on each implant surface. To analyze the plaque condition on implants surfaces, cell count and optical density were taken as a microbiologic method, and SEM(Scanning Electronic Microscope) findings was also taken for evaluation of surface condition. The following results were obtained. 1. Cell counting results of artificial dental plaque were Uncoated group($658.0{\pm}102.0$), RBM group($878.0{\pm}170.0$), SLA group ($946.0{\pm}42.0$), Oxidized group($992.0{\pm}40.0$), and there was difference between Oxidized group and Uncoated implant group(p<0.05). In case of modified cell counting results by v/w% were RBM group($197.8{\pm}45.2$), Oxidized group($207.04{\pm}8.34$), Uncoated group($261.6{\pm}40.6$), SLA group($315.4{\pm}14.0$), and there was difference between RBM group and SLA group(p<0.05). 2. Optical density results of artificial dental plaque after ultrasonic treatment was that there was difference among groups, and optical density of RBM group was higher than that of Uncoated group(p<0.05). In case of modified optical density results by v/w%, there was difference among groups, and the modified optical density of Uncoated group and SLA group was higher than those of Oxidized group and RBM group(P>0.05). 3. SEM findings of artificial dental plaque on the surfaces of implant as follows; there were artificial dental plaque on the surfaces of all test implants. Streptococcus mutans and by-product were observed at 10,000 times magnified condition on all test implants. Adhesion area of artificial dental plaque was about 1/2 of total surface after 24 hours incubate at $37^{\circ}C$. These results showed that there were differences among implant surfaces on the growth of Streptococcus mutans, and bacteria and by-product were covered about 1/2 area of total implant surfaces at 24 hours incubate at $37^{\circ}C$.

• Journal of muscle and joint health
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• v.7 no.2
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• pp.294-308
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• 2000

This study was conducted to test the effect of brisk walking & muscle strengthening exercise program on bone mineral density(BMD) of the lumbar & femur in rheumatoid arthritis women. Research design was a quasi-experimental study of non-equivalent control group pretest-posttest design(16 weeks). 14 for the experimental group and 14 for the control group were selected from the outpatients on rheumatoid arthritis clinic of Dong-A University Hospital. The experimental group underwent 16 weeks of brisk walking and muscle strengthening exercise. Bone mineral density was measured before and after 16 weeks of exercise by DXA at lumbar spine, femoral neck, Ward's triangle and trochanter. The results were summarized as follows : 1. BMD of the lumbar spine in experimental group who carried out the brisk walking and muscle strengthening exercise was not significantly increased after 16weeks and there was no significant difference between experimental and control group(U=70.00 p>.05). 2. BMD of the femoral neck in the experimental group who carried out the brisk walking and muscle strengthening exercises was significantly increased after 16 weeks(Z=-2.901 p<.01). But, there was no significant difference between experimental and control group(U=83.00 p>.05). 3. BMD of the femoral Ward's triangle in the experimental group who carried out the brisk walking and muscle strengthening exercises was significantly increased after 16 weeks (Z=-2.355 p<.05). But, there was no significant difference between experimental and control group(U=86.00 p>.05). 4. BMD of the femoral trochanter in experimental group who carried out the brisk walking and muscle strengthening exercise was not significantly increased after 16weeks and there was no significant difference between experimental and control group(U=75.00 p>.05). These results suggest that brisk walking and muscle strengthening exercise program has an effect on promoting bone mineral density of femoral neck and Ward's triangle in rheumatoid arthritis women.

• Proceedings of the Korean Society for Information Management Conference
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• 2000.08a
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• pp.129-132
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• 2000

GIS(Geographic Information System) tool has been applied to determine a spatial difference of weed population density in paddy field and it has introduced to rice yield difference among counties as well as to rice blast in Korea. There was highly difference between sampling sites in terms of spatial analysis which may imply to be able to apply this tool for the precesion agriculture in the 21 century.

• Journal of Yeungnam Medical Science
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• v.14 no.2
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• pp.383-392
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• 1997

To study the differences of bone mineral density according to the gestational ages and the birth weight and get a reference data for the diagnosis of metabolic bone diseases in the newborn infants, bone mineral densities of the lumbar vertebrae were measured in fifty-three newborn infants born at Yeungnam University Hospital from March 1, 1995 to February 28, 1997, whore gestational ages were between $28^{+3}$ and $41^{+3}$ weeks and who had no intrauterine growth retardation, using dual energy X-ray absorptiometry (X-R 26, Norland, USA) within seven days of life. 1. There was no sexual difference in bone mineral density. The bone density increased significantly as gestational age increased from $0.149{\pm}0.009g/cm^2$ at 28-30wks to $0.229{\pm}0.034g/cm^2$ at 39-41wks of gestational age (p<0.05), but there was no significant difference between bone mineral densities at 33-34 wks and 35-36wks. There was positive linear correlation between gestational age and bone mineral density ($Y=7.5{\times}10^{-3}X-0.082$, r=0.7018, p<0.001). 2. The bone mineral density increased significantly as the birth weight increased from $0.158{\pm}0.020g/cm^2$ in 1,000-1,499 g to $0.251{\pm}0.021g/cm^2$ in 3,500-4,000 g of the birth weight (p<0.05), but there was no significant difference between bone mineral densities in 1,000-1,499 g and 1,500-1,999 g of the birth weight. There was positive linear correlation between the birth weight and the bone mineral density ($Y=3.9{\times}10^{-5}X+0.093$, r=0.7296, p<0.001). There were positive correlations between the bone mineral density and gestational age, and between the bone mineral density and the birth weight. It can be used as a reference data for the further study on the bone mineral metabolism in the newborn infants including preterm babies.

• Asian Journal of Turfgrass Science
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• v.3 no.1
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• pp.5-12
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• 1989

Tiller numbers per Unit area were increased as plant density heightened followed by little difference in tiller number in 110 days after transplanting(ll0DAT), this being caused by the immediate increment of tiller since' 90DAT During the growth period, the greatest number of green leaves per unit area was attained in 90DAT of both 160-density and 200-density plots, and in l00DAT of 40-, 80-, and I 20-density plots. Thus, the period to reach the maximum green leaf number with the high plant density was earlier than with the' low plant density. The increment of plant density increased the DM weight of ahoveground part and, with 40-densitytreatment. DNI weight was increased 6.1 times as much up to 110DAT as up to 7ODAT but 2 to 2.9 times with other ehe'nsity treatments. The' rate of increase in stolon length was greatest at the period between 80 and 90DAT when DM weight of stolon showed a large increment. Meanwhile, the average number of stolon was 1.7 at 70DAT but was increased up to 10 at 110DAT probably due to accelerative appeance of Ist stolon branch since 8.0DAT. DM weight of stolon was found to exceeded that of root after 90DAT Thus it was concluded that, when turfs is estahlished from sprig. it may be desirable for first mowing practice to be made at least within l00 days after planting.

• Journal of International Academy of Physical Therapy Research
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• v.2 no.2
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• pp.267-273
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• 2011

The purpose of this study is to examine the changes in bone mineral density in long-stay patients of a geriatric hospital in relation to physical therapy, thereby providing basic data for preventing the onset or deterioration of osteoporosis in inpatients of geriatric hospitals or relevant facilities. The subjects of this study were 133 elderly patients who had been in H geriatric hospital in Yongin-si for more than four years. Their bone mineral density T-scores at admission and those after four years were measured to compare and analyze the changes in bone mineral density in relation to physical therapy. According to the results, the decrease in T-score for the group without physical therapy was greater by .40 than that for the group with physical therapy, indicating a statistically significant difference between the two groups(p<.01). Accordingly, physical therapy proved to be effective in preventing bone mineral density loss and maintaining the current density.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.4
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• pp.67-74
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• 2004

As data rate was increased, the conventional burst-mode automatic power control circuit caused errors due to the effort of the mark density variation. To solve this problem we invented a new structured peak-comparator which could eliminate the effect of the mark density variation even in high date rate, and revised the conventional one using it. We proposed a burst-mode automatic power control circuit robust to mark density variations. We found that the peak-comparator in the proposed automatic power control circuit was very robust to mark density variations because it affected very little by the mark density variation in high date rate and in the wide variation range of the reference current and the difference current.

• Journal of Korea Game Society
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• v.17 no.4
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• pp.55-62
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• 2017

In this study, motion simulation of Walk-through was evaluated with HMD(Head Mounted Display). More Specifically, we examined the changes of the degree of object density placed around virtual space on psychological moving distance, moving speed, and moving time. The results were as follows. First, the difference between the experimental conditions(low density, Medium density, High density) was significant. Second, as the density of the surrounding objects increased, the average point of moving time, moving speed, and moving distance rose compared to the basic conditions. Third, it was found that the surrounding objects improved the sense of time, speed and distance in motion simulation in virtual space.

• Advances in biomechanics and applications
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• v.1 no.1
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• pp.15-22
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• 2014

Computed tomography (CT) is being utilized in orthopaedics and related research to estimate bone strength. These applications benefit from calibration of Hounsfield units to mineral density typical of long bone, up to $1750mg/cm^3$. This study describes a method for establishing repeatable calibration of Hounsfield units to density, and determines the effects of imaging medium on calibration accuracy. Four hydroxyapatite standards were imaged in air on 7 occasions over 19 weeks using a helical multi-slice CT scanner. Each standard was scanned 5 times in different media: porcine soft tissue, water, and air. Calibrated densities were highly repeatable (CV<3.5%). No difference in density was observed between water and soft tissue conditions (p>0.08). This work provides a model for determining repeatable scanner-specific density calibration, demonstrates that the linear relationship between Hounsfield units and density extends to values typical of cortical bone, and supports the practice of imaging calibration standards in an environment similar to that of the target bone.