• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.249-258
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• 2013

The purpose of this study was to investigate how image magnification in dental panoramic radiography is influenced by object position. Five metal balls (4 mm in diameter, 2 for the anterior and 3 for the posterior region on the right side) were placed above alveolar crest of dry skull considering extraction socket and dental arch. Dry skull was radiographed using OP-100D (Instrumentarium Imaging Co., Tuusula, Finland) at proper and displaced position along the sagittal and transverse plane at 3 mm, 6 mm, 9 mm, 12 mm and 15 mm using special mount which can control precise movement. Images were stored in DICOM files and were measured by ruler equipped within INFINITT PACS software (Infinitt Co., Ltd., Seoul, Korea). The mean horizontal magnification was 1.224-1.439 and mean vertical magnification was 1.286 - 1.345 at proper position. Vertical magnification resulted in less variation (1.245-1.418) than horizontal magnification (0.798-6.297) according to the sagittal and transverse displacements. Head positioning is important for linear measurement on panoramic radiography and inclusion of standard object (for instance, metal ball) is helpful to anticipate exact magnification of panoramic radiographs at various location.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.1-8
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• 2014

Purpose: The purpose of this study was to investigate the effect of head position changes on vertical and horizontal magnification in dental panoramic radiographs. Materials and Methods: Five 4 mm metal balls were placed above alveolar crest of dry skull considering extraction socket and dental arch. Panoramic radiographs were taken by OP-100D (Instrumentarium Imaging Co., Tuusula, Finland) at proper and rotated head position along the sagittal and transverse axis at 3 - $20^{\circ}$ upwardly, downwardly, to the left and to the right rotation. Images were stored in DICOM files and were measured by ruler equipped within INFINITT PACS software. Results: The mean horizontal magnification was $1.22{\pm}0.01-1.44{\pm}0.01$ and mean vertical magnification was $1.29{\pm}0.00-1.35{\pm}0.02$ at standard head position. There was statistical significance of horizontal magnification between the anterior ($1.24{\pm}0.02-1.31{\pm}0.03$) and the posterior area ($1.40{\pm}0.03-1.33{\pm}0.02$) (P < 0.05). Vertical magnification resulted in less variation ($1.24{\pm}0.01-1.37{\pm}0.02$) than horizontal magnification ($0.88{\pm}0.03-3.73{\pm}0.16$) according to the rotation. There was statistical significant difference on horizontal magnification (P < 0.05). Conclusion: In rotated head position, the horizontal magnification should be considered because these can cause distortion on panoramic radiographs.

• Fire Science and Engineering
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• v.23 no.5
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• pp.143-152
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• 2009

The numerical analyses for each single simplified shaft with three type openings were carried out by using computational fluid dynamics model for the calculation of the pressure difference and the location of the neutral plane and the visualization of stack effect. As the height of shaft heighten, the pressure difference of stack effect is much deviated against the theoretical value. For the Type A models shorter than 30 m height of shaft and the Type B models longer than 30m, the simulation results for the location of the neutral plane are well agreed to the theoretical values with 5% less deviations just after the beginning of simulation (t = 10s). For the Type B models longer than 30m with multiple openings, therefore, it is possible to calculate the location of the neutral plane by using a CFD model. The phenomenon of the air flow of stack effect can be easily understood with the visualization of stack effect.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.273-275
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• 2015

GPS(Global Positioning System; 위성항법시스템)는 수평오차 10m 내외의 정확도로 내비게이션 유닛과 스마트폰 등 다양한 이동기기에 널리 활용되고 있다. 그러나 널리 알려진 바와 같이 GPS는 교량, 빌딩, 그리고 대형 구조물 등 주변 환경에 의하여 위성의 가시성이 영향을 받으며 이로 인하여 위치 정보의 가용성과 정확도가 크게 저하되는 단점이 있다. 본 논문에서는 GPS 수직오차를 개선하기 위한 방안으로 저가형 기압고도계를 보조센서로 활용하여 수직 위치정보 정확도를 향상시키는 방법을 제안하였다. 제안된 방법은 융합 모델에 의한 칼만필터를 활용하여 GPS와 기압고도계를 융합하는 특성을 가진다. 마지막으로 정적 실험과 동적 실험을 통하여 기압고도계의 특성을 분석하고 제안된 융합 필터의 성능을 분석하였다.

• The korean journal of orthodontics
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• v.27 no.5 s.64
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• pp.743-760
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• 1997

This study was done to evaluate the correlations between the size, the form of the cranial base, head posture and the horizontal and vertical position of craniofacial structures. For this purpose, 100 cephalometric radiographs were taken from the sample composed of 51 male and 49 female, 12 measurement criteria and 37 reference points were established and digitized, then calculation was performed for the values of measurement variables and the horizontal and vertical position of reference points. The correlations be4ween them were analyzed statistically and mean facial diagrams were constructed and compared with the selected groups which were composed of 10 Samples each as large and small group from the measurement value. The following results were obtained: 1. The angles n-s-ba and n-s-ar as variables for the ion of cranial base correlated highly to the horizontal and vertical position of reference points in the cervical column with statistical significance($0.1\%$ level). 2. The angles n-s-ba and n-s-ar as variables for the form of cranial base correlated to the horizontal position of the reference points in the facial structure with statistical significance($1\%$ level), but not to the vertical position of them($5\%$ level). 3. The length n-s, s-ba, and n-ar as variables for the size of cranial base were correlated th the position of craniofacial structures in various ways, but in general, highly correlated to the horizontal and vertical position of midfacial structures around the teeth and alveolar area. 4. the angle NSL/CVT and NSL/OPT as postural variables tot the inclination of cranial base and cervical column were correlated to the horizontal position of the craniofacial structures with statistical significance($1\%$ level), but not to the vortical position of them($5\%$ level). 5. The angle OPT/HOR and CVT/HOR as postural variables lot the inclination of cranial base and true horizontal line were not correlated to the horizontal and vertical position of the craniofacial structures with statistical significance($5\%$ level). 6. The correlation between the measurement variables and horizontal and vortical positions of the reference poits in soft tissue were shown as similar to the related hard tissue points.

• Journal of the Korean GEO-environmental Society
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• v.14 no.8
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• pp.45-51
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• 2013

In the construction site of underground buildings which have severe environment such as dust, noise, vibration, the technology of rescue the builders in the construction site when accident occurs by tracking the location of the builders and express the mission of supervisor smoothly. In this study, in order to acquire the location information of the builders in the construction site of underground buildings by using MEMS INS and air pressure sensor, we firstly performed the field test in construction site, analyzed the location and the elevation accuracy based on the detected results, and then verified its practicality and rationality after all. As a result, we could acquire worker's position-accuracy within 10m in horizontal direction and 4m in vertical direction. Therefore we could judge availability in construction fields of underground structure.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.4 s.38
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• pp.11-18
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• 2006

In this paper, airborne LiDAR data were evaluated in horizontal and vertical accuracy. By using zigzag scanning type of LiDAR, GCPs are not tested directly. So points around GCPs were used in this evaluation. Building corner points were made from LiDAR's building planar and compared with ground surveyed GCPs, in horizontal accuracy test. Its accuracy shows 19cm average and 21cm RMSE and 15 points were within 20cm among 16 points. In vertical accuracy test, 41 GCPs were used and it shows 11cm average and 14cm RMSE and 75% of GCPs were within 15cm. This could be a criterion in topographic map modification and basic geographic DB and 3D data construction using airborne LiDAR data.

• Fire Science and Engineering
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• v.25 no.4
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• pp.74-81
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• 2011

The numerical analyses for three different shafts in geometry of high buildings were carried out by using computational fluid dynamics model (FDS ver.5.3) for the calculation of the pressure difference and the location of the neutral plane and the visualization of stack effect. At 10 seconds of stack effect, the pressure difference of stack effect in the elevator shaft (79.3 Pa) almost corresponded to the theoretical value (78 Pa). At 300 seconds of stack effect, all the neutral planes of three cases were located about 49 m above floor, where was 5 m higher than the theoretical value. The maximum pressure difference between upper and lower position of shaft decreased with increasing of the geometrical complexity of shaft. This study showed that there was the difference of the stack effects among the geometries of shafts with the visualization of stack effect.

• Journal of Digital Convergence
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• v.15 no.10
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• pp.307-314
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• 2017

In this study, a minimum amount of the vertical occlusion was secured differently in each type of mandibular advance devices snoring and Class I malocclusion patients wore these devices. This study analyzes, after the use of devices, a different amount of the vertical occlusion results in a change of the area of upper airway by additional changes such as mandibular position, muscle changes, tongue position. The higher the vertical amount, the area of the upper airway was shown smaller, And if the patient's tongues was prevented from the distal movement, the area of the upper airway had increased, To reduce snoring, doctors should accurately diagnose patients' occlusal relationships and select a MAD snoring that is appropriate for the occlusion. The dental technician who builds the selected device should also consider design settings such as the amount of vertical occlusion, the finish lines, and the thickness of the device to increase the effectiveness of the device.

• 한국공간정보시스템학회:학술대회논문집
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• 2000.06a
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• pp.67-76
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• 2000

Recently, SAR Interferometry method is actively being studied as a new technic in topographic mapping using satellite imageries. it extract height values using two SAR imageries covering same areas. Unlike when using SPOT imageries, it isn't affected by atmospheric conditions and time. But it is difficult to process radar imageries and the height accuracy is very low where relief displacements are high. In this study, we produced DEM(Digital Elevation Model) using ERS-1, ERS-2 tandem data and analysed the height accuracy over 14 ground control points. The mean error in height was 14.06m. But when using airborne SAR data, it Is expected that we can produce more accurate DEM which will be able to ue used in updating 1/10,000 or 1/25,000 map.