• Imaging Science in Dentistry
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• v.34 no.3
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• pp.123-128
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• 2004

Purpose: To evaluate the reliability of measurements in spiral tomography through assessing the visibility of the alveolar crest and the measurements between the alveolar crest and other anatomic structures. Materials and Methods: 110 spiral tomograms of the jaws were taken by Scanora X-ray unit from the patients. The visibility of the alveolar crests was estimated by 3 observers and classified as clearly visible, questionable visibility, or not visible. 3 observers measured the distance between the alveolar crest and the reference points of anatomic structures. The measurements were repeated 2 weeks later. Results: 52.9% of alveolar crests on upper jaws and 61.5% of alveolar crests on lower jaws were visible. The interobserver and intraobserver agreements on the visibility were low. The mean ranges of the measurements were 1.39 mm (SD = 1.37 mm) on maxilla and 1.03 mm (SD = 1.01 mm) on mandible in the interobserver evaluation. The interobserver variance was greater than the intraobserver variance in the measurements of distance. Conclusion: Spiral tomography showed a relatively low reliability in the visibility and measurements of the alveolar crest.

• Journal of Astronomy and Space Sciences
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• v.35 no.4
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• pp.287-293
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• 2018

This paper presents a satellite relative navigation strategy for formation flying, which chooses an appropriate navigation algorithm according to the operating environment. Not only global positioning system (GPS) measurements, but laser measurements can also be utilized to determine the relative positions of satellites. Laser data is used solely or together with GPS measurements. Numerical simulations were conducted to compare the relative navigation algorithm using only laser data and laser data combined with GPS data. If an accurate direction of laser pointing is estimated, the relative position of satellites can be determined using only laser measurements. If not, the combined algorithm has better performance, and is irrelevant to the precision of the relative angle data between two satellites in spherical coordinates. Within 10 km relative distance between satellites, relative navigation using double difference GPS data makes more precise relative position estimation results. If the simulation results are applied to the relative navigation strategy, the proper algorithm can be chosen, and the relative position of satellites can be estimated precisely in changing mission environments.

• The Journal of Korea Robotics Society
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• v.18 no.3
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• pp.330-336
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• 2023

In this paper, a novel line-based simultaneous localization and mapping (SLAM) using a loss function of vanishing point measurements is proposed. In general, the Huber norm is used as a loss function for point and line features in feature-based SLAM. The proposed loss function of vanishing point measurements is based on the unit sphere model. Because the point and line feature measurements define the reprojection error in the image plane as a residual, linear loss functions such as the Huber norm is used. However, the typical loss functions are not suitable for vanishing point measurements with unbounded problems. To tackle this problem, we propose a loss function for vanishing point measurements. The proposed loss function is based on unit sphere model. Finally, we prove the validity of the loss function for vanishing point through experiments on a public dataset.

• The korean journal of orthodontics
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• v.29 no.5 s.76
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• pp.563-573
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• 1999

The purpose of this study was to evaluate the availability of computer system for the measurement of tooth size in the model analysis through the comparison of two measurements: One was to use a computer; and the other was to use vernier calipers. Twenty sets of casts were used, which showed a moderate degree of crowding and full eruption of all teeth. The mesio-distal width of 12 teeth from the left central incisor to the left first molar at each set of the casts were measured twice with vernier calipers and a computer respectively. This measurement was repeated two weeks later. First, for the reproducibility analysis, the two computer measurements were compared then the vernier calipers measurements were compared. Second, all the teeth were sepapated into the region of mesiodistal contact points and its width was measured by a micrometer to obtain standard measurements. For the accuracy analysis, these standard measurements were compared with the measurements from the dental casts using two methods. The difference between them was defined as the measurement error. To investigate the cause of measurement error, an examination was made for the presence and degree of contact point deviation on each tooth from the upper and lower occlusograms, and the mesio-distal angulation of each tooth was measured with TARG. Following results were obtained through statistical analysis. 1. In the analysis for reproducibility; the measurements with vernier calipers showed significant differences in three out of twelve teeth while the computer measurements showed significant differences in one out of twelve teeth. 2. In the analysis for accuracy; compared with the standard measurements, the measurements with vernier calipers showed significant differences in three out of twelve teeth while the computer measurements showed significant differences in two out of twelve teeth. 3. Compared with the standard measurements, the measurements with vernier calipers were apt to be larger at the upper first molar, and smaller at the lower first molar The computer measurements, however, were apt to be larger at both upper and lower first molars. 4. The measurements with vernier calipers showed the largest error at the lower first molar and the degree of error was variable according to the tooth while the difference of error was small in the computer measurements. 5. In the analysis for the correlation of the degree of measurement errors with the contact point deviation index and the mesio-distal crown angulation of each tooth, the measurements with vernier calipers did not show significant correlation while the measurements with computer showed slight Positive correlations. The results of this study indicate that a computer system may be useful for the measurement of tooth size in the model analysis.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.10a
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• pp.415-422
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• 1998

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.8
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• pp.1190-1202
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• 2009

A 3D body scan measurement (SM) is used as an alternative to physical measurements (PM) as the information for designing industrial products. This study compared the mean difference (MD) between SM and PM by gender and analyzed the causes of the difference. The data used in this study were the scan measurements and physical measurements of adults aged twenty to seventy years old of the fifth Size Korea survey. The results of this study are as follows: 1. The comparison of MD between men and women for all subjects: The measurement of the significant differences between men and women were height, neck base girth, chest girth, under-bust girth, waist girth, armscye girth, back length, and foot length. The causes of difference are the difference of body shape. 2. The comparison of MD between men and women by BMI groups: Many measurements had significant differences between men and women at normal weight and overweight but underweight. Some measurements had significant differences only at a specific BMI group because the body shape difference between men and women is revealed clearly in the group. The comparison of MD between men and women by age groups: The measurements that show significant difference at more than four age groups were neck girth, chest girth, under-bust girth, waist girth, armscye girth, and foot length. The height and abdomen girth had a significant difference in the age range of 20's and 30's. There were measurements that increase MD with an increase in age; under-bust girth and lateral shoulder length for women and lateral shoulder length for men. This comparison of MD between men and women provide the correct guidelines for the use of SM.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.3
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• pp.249-260
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• 2012

Monitoring of climate change and atmospheric environment by satellite measurements has been increased in recent years. In this study, nitrogen dioxide ($NO_2$) measurements from Ozone Monitoring Instrument (OMI) were compared with surface measurements over the Korean peninsula. $NO_2$ from OMI measurements showed high values and also showed seasonal variations such as high concentration in winter and low in summer over metropolitan areas while $NO_2$ concentration at national background station was low and did not clearly show seasonal variations. Surface measurements showed similar temporal and spatial variations to those of satellite measurement. The comparison between satellite measurements and surface measurements showed that the correlation between them was higher in urban area (r=0.64 at Seoul and r=0.63 at Daegu) than in national background stations (r=0.37 at Jeju) because the concentration in urban area was relatively high so that the variation of $NO_2$ concentration could be detected better than at national background stations by satellite. Satellite can effectively measure the emission and transport of pollutants with no limitations in spatial coverage.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.1
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• pp.43-59
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• 2017

This study used data from a survey of adult Korean women in their twenties to learn their current practices for wearing and purchasing tight-fit jeans available on the market as well as perceptions regarding size measurements and satisfaction levels. We then determined product sizes and pattern measurements for the type of jeans worn. This study also analyzed discrepancies in product size measurements among brands to determine whether the measurements were generally suitable for average body shapes and measurements of women in their twenties. The study results were as follows. First, the survey asked women in their twenties about current practices in wearing jeans. Many respondents answered that their preferred fit is "a perfectly snug fit" and that the most common fit style of jeans was the skinny fit. Second, we selected a test pair of jeans with an identical fiber content from brands that women prefer to wear, according to the survey results. We researched the product measurements of the size respectively labeled 27 inches for each of the 8 brands' test jeans; consequently, the results showed that there were significant differences among the brands in the product measurements of each part of jeans. Third, we analyzed the pattern measurements of 8 selected brands for each area and identified pattern characteristics by brand.

• Nutritional Sciences
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• v.6 no.2
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• pp.113-117
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• 2003

Possible correlations between nutrient intake add health status-as assessed by anthropometric measurements, physical performance and biochemical measurements-were investigated, using 514 healthy young men aged 20 years old who had no apparent health problems. The intakes of nutrients were estimated using a three-day dietary recall method. Height and body weight were measured, and body mass index (BMI) was calculated. Physical performance was tested using sit-ups, push-ups, a loom sprint and a 1,500m run. When compared with the Korean recommended dietary allowances (Korean RDA), the subjects nutrient intakes were adequate except for calcium. The intake of calcium was 516.66$\pm$293.43mg/day, which is 73.80 % of the Korean RDA. The subjects averaged 174.51$\pm$7.07cm in height, 68.17$\pm$9.25 kg in body weight and 22.23$\pm$2.16 in BMI. The associations between nutrient intakes and anthropometric measurements, and between nutrient intakes and physical performance, were weak. The intake of vegetable fat was positively correlated to body weight, whereas the intake of carbohydrate was negatively correlated to BMI. The intake of carbohydrate was positively correlated to the level of performance in the loom sprint, and the intake of vegetable Int was positively correlated to the level of performance of sit-ups. No correlation was found between nutrient intakes and the following biochemical measurements of the blood: the levels of glucose, total protein, total cholesterol, triglyceride, hemoglobin and hematocrit. These results suggest that anthropometric measurements and level of physical performance can be associated with energy nutrient intakes, even in moderately active, well-nourished, young men. No correlation was found between nutrient intake and biochemical measurements, probably because all subjects had a reasonably well-balanced diet.

• Imaging Science in Dentistry
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• v.31 no.2
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• pp.101-107
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• 2001

Purpose: To evaluate the precision of measurements of distances and angle in the cross-sectional views of linear tomogram of panorama and to assess the technique for visualizing the mandibular canal. Methods: Ten dry mandibles were radiographically examined with 3 continuous cross-sectional views of linear tomogram of panorama and 4 continuous computed tomograms. The distance between the superior border of canal and alveolar crest and the bucco-lingual width of alveolar bone at the level of the superior border of canal and the angle between the two lines above were measured. Measurements were performed by radiologist and implantologist group and compared with measurements on computed radiograms of the same areas. Results: The measurements differences for the distance of alveolar bone height between in panorama and in CT showed 0.9 mm±0.6 mm by radiologists and 1.3mm±0.8mm by implantologists. There was no statistically significant difference between two groups' measurements. The differences in measurements for the distance of alveolar bone width between in panorama and in CT showed 0.5mm±0.8mm by radiologists and 2.5mm±1.4 mm by implantologists. There was significant difference (P<0.05) between two groups' measurements. The average bucco-lingual inclination of alveolar bone above mandibular canal was average 95.8° in CT. The difference of measurements between two groups was average 1±0.9°. Three cross-sectional views of panorama could show that the mandibular canal crosses antero-lingually and slopes inferiorly from the posterior segment of the mandible. Conclusions: The measurements in the linear tomogram of panorama by radiologists gave the accurate values of the distances and the angle compared with the values in computed tomograms.