• Journal of Yeungnam Medical Science
• /
• v.18 no.1
• /
• pp.123-137
• /
• 2001

Background: The purpose of this study is to evaluate the accuracy of measurements obtained from 3-dimensional computerized tomography and 3-dimensional cephalogram constructed by using the frontal and lateral cephalogram of six human dry skulls. Materials and Methods: After CT scans and each cephalograms were taken, 3-dimensional coordinates (X, Y, Z) of landmarks were obtained using computer programs. In this study, the accuracy of both methods were determined by means of 14 linear measurements compare with caliper measurements. Results: The standard deviation of landmarks of 3-dimensional CT and 3-dimensional cephalogram were 0.23 mm, and 0.30 mm in X axis, 0.27 mm and 0.25 mm in Y axis, and 0.27 mm and 0.31 mm in Z axis. In both methods, the standard deviation were less than 0.5 mm in all landmarks, and the most of landmarks showed less than 1 mm in range. Concerning the accuracy, the mean difference between 3-dimensional CT and manual measurements was 0.33 mm, and 1.13 mm between 3-dimensional cephalogram and manual measurements. The distance between RGo and LGo showed the largest difference (2.03 mm). There were highly significant, and large correlation with manual measurements in both methods (p<0.01). Conclusion: It is concluded that closeness of repeated measures to each skulls reveal the precision of both methods. Computerized tomography and cephalogram for 3-dimensional measurement of maxillofacial structure are equivalent in quality to caliper measurements.

• Imaging Science in Dentistry
• /
• v.43 no.3
• /
• pp.185-190
• /
• 2013

Purpose: The aim of the present study was to evaluate the measurement accuracy of endodontic file length on periapical digital radiography after application of noise reduction digital enhancement. Materials and Methods: Thirty-five human single-rooted permanent teeth with canals measuring 20-24 mm in length were selected. ISO #08 endodontic files were placed in the root canals of the teeth. The file lengths were measured with a digital caliper as the standard value. Standard periapical digital images were obtained using the Digora digital radiographic system and a dental X-ray unit. In order to produce the enhanced images, the noise reduction option was applied. Two blinded radiologists measured the file lengths on the original and enhanced images. The measurements were compared by repeated measures ANOVA and the Bonferroni test (${\alpha}=0.05$). Results: Both the original and enhanced digital images provided significantly longer measurements compared with the standard value (P<0.05). There were no significant differences between the measurement accuracy of the original and enhanced images (P>0.05). Conclusion: Noise reduction digital enhancement did not influence the measurement accuracy of the length of the thin endodontic files on the digital periapical radiographs despite the fact that noise reduction could result in the elimination of fine details of the images.

• The Journal of Advanced Prosthodontics
• /
• v.10 no.2
• /
• pp.122-127
• /
• 2018

PURPOSE. This study evaluated the dimensional stability of a complete-arch prosthesis processed by conventional method in water bath or microwave energy and polymerized by two different curing cycles. MATERIALS AND METHODS. Forty maxillary complete-arch prostheses were randomly divided into four groups (n = 10): MW1 - acrylic resin cured by one microwave cycle; MW2 - acrylic resin cured by two microwave cycles: WB1 - conventional acrylic resin polymerized using one curing cycle in a water bath; WB2 - conventional acrylic resin polymerized using two curing cycles in a water bath. For evaluation of dimensional stability, occlusal vertical dimension (OVD) and area of contact points were measured in two different measurement times: before and after the polymerization method. A digital caliper was used for OVD measurement. Occlusal contact registration strips were used between maxillary and mandibular dentures to measure the contact points. The images were measured using the software IpWin32, and the differences before and after the polymerization methods were calculated. The data were statistically analyzed using the one-way ANOVA and Tukey test (${\alpha}=.05$). RESULTS. The results demonstrated significant statistical differences for OVD between different measurement times for all groups. MW1 presented the highest OVD values, while WB2 had the lowest OVD values (P<.05). No statistical differences were found for area of contact points among the groups (P=.7150). CONCLUSION. The conventional acrylic resin polymerized using two curing cycles in a water bath led to less difference in OVD of complete-arch prosthesis.

• Journal of Korean Foot and Ankle Society
• /
• v.18 no.1
• /
• pp.14-18
• /
• 2014

Purpose: The purpose of this report is to evaluate the measured values of normal Korean calcaneus by conduct of a cadaveric study. Materials and Methods: A total of 42 calcanei were obtained from Korean cadavers. A digital goniometer was used for measurement of B$\ddot{o}$hler's angle, Gissane angle, posterior facet articular inclination angle, and Fowler-Philip angle of calcaneus. A vernier caliper was used for measurement of the maximal antero-posterior length, maximal transverse width, and maximal height of calcaneus. Results: The average B$\ddot{o}$hler's angle, Gissane angle, posterior facet articular inclination angle, and Fowler-Philip angle was $32.3^{\circ}{\pm}5.0^{\circ}$, $114.4^{\circ}{\pm}8.2^{\circ}$, $61.2^{\circ}{\pm}4.4^{\circ}$, and $60.3^{\circ}{\pm}7.6^{\circ}$. The average maximal antero-posterior length, maximal transverse width, and maximal height of calcaneus was $74.2{\pm}3.0mm$, $43.0{\pm}4.0mm$, and $42.5{\pm}3.0mm$. Conclusion: The measured values of normal Korean calcaneus were lower than the values reported in the international literature. Therefore, development of appropriate instruments reflecting the anatomical characteristics of Koreans will be needed.

• Journal of Korean Society of Forest Science
• /
• v.110 no.1
• /
• pp.72-81
• /
• 2021

We developed smartphone application and web application server to acquire and effectively manage tree measurement information. Smartphone applications can measure tree height, diameter at breast height (DBH), azimuth, altitude, slope, and positional coordinates using augmented reality (Google AR core) and motion sensors. The web application server effectively manages and stores measurement information. To evaluate the accuracy of information acquired using a smartphone, 90 Korean pine trees (Pinus koraiensis) were randomly selected from a natural mixed forest, with a total of 90 representative trees randomly collected from a natural mixed forest. Then, height and DBH were measured using a Haglof Vertex Laser Hypsometer and caliper. Comparisons of the results indicated significant results at the 95% level and a very high average correlation of 0.972 for both tree height and DBH. In terms of DBH, the average errors were 0.6745 cm and 1.0139 cm for artificial coniferous and natural mixed forests, respectively.

• Korean Journal of Veterinary Research
• /
• v.14 no.2
• /
• pp.185-189
• /
• 1974

Although considerable research has been done on the blood chemistry of domestic animals, little work has been made of the changes associated with age. Moreover, the records about physiology of the goat were not much available in Korea, and a comprehensive survey of the blood chemical values of the Korean native goat has not been made. The authors intended to biometric study on the hardness of bone of race horse and Jeju horse in Korea. The measurement of hardness of bone were performed in 272 race horses (Thoroughbred 91, Anglo-Arab 107, Arab 74) and in 109 Jeju horses by the caliper by Toryba's method. Some interesting facts obtained through this study were as follows: 1. There was not significant difference of bone hardness between male and female. The average of bone hardness by the Toryba's meteod were $23.07{\pm}1.01$ in race horse and $19.44{\pm}1.84$ in Jeju horse. 2. The grade of bone hardness of race horse were higher than those of Jeju horse(P<0.001). 3. The correlation coefficient between age and grade of bone hardness were r= +0.344 in Jeju horse, theme were statistically significant (P<0.01) and the regression equation was Y=0.29x+18.497.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.24 no.5
• /
• pp.520-526
• /
• 2016

Squeal noise is a typical brake noise that is annoying to both passengers and pedestrians. Its frequency range is fairly wide from 1 kHz to 18 kHz, which can be distressful to people. The brake squeal noise occurs due to various mechanisms, such as the mode coupling of the brake system, self-excited vibration, unstable wear, and others. In this study, several parameters involved in the generation of a squeal noise are investigated experimentally by using a brake noise dynamometer. The speed, caliper pressure, torque, and friction coefficient are measured as functions of time on the dynamometer. The contact pressure and temperature distributions of the disc and the pad are also measured by using a thermal imaging camera and a pressure mapping system. As a result of the simultaneous measurement of the friction coefficient and squeal amplitude as functions of the velocity, it is found that the onset of the squeal may be predicted from the ${\mu}-v$ curve. It is also found that a non-uniform contact pressure causes instability and, in turn, a squeal. Based on the analysis results, design modifications of the pad are suggested for improved noise characteristics.

• Proceedings of the KIEE Conference
• /
• 2001.07d
• /
• pp.2190-2192
• /
• 2001

가스 배관 진단 시스템은 배관 내부에 삽입되어 배관 내에 주입된 가스에 의해 추진되는 시스템으로 배관의 건설, 유지, 보수, 해체 등의 작업을 위한 여러 정보를 수집한다. 배관 진단을 위한 대표적인 센서로는 배관 내부의 찌그러짐(dent)과 주름(wrinkle)의 형태 및 크기를 측정하는 캘리퍼(caliper) 센서와 배관 외부의 파손을 측정하는 MFL(Magnetic Flus Leakage) 센서 그리고 배관 내의 환경 정보를 측정하기 위한 온도 센서와 압력 센서가 있다. 이러한 센서들로 수집된 정보를 활용하기 위해서는 정확한 위치 정보가 필요하므로 IMU(Inertial Measurement Unit)와 주행 거리계를 사용하는 결합 항법 시스템도 필요하다. 본 논문에서는 가스 배관 진단 시스템을 위한 항법 데이터 저장 시스템을 개발한다. 배관 진단 시스템의 특성상 일반적인 측정 센서는 700Hz 이상의 주기로 측정되고 항법 정보는 100Hz 주기 이상으로 측정되며 배관 내 이동 시간은 2시간에서 24시간 이상으로 다양하므로 많은 데이터를 효율적으로 저장할 수 있어야 한다. 따라서 데이터 저장 장치로는 DAT를 사용하게 되며 많은 센서 데이터를 실시간으로 저장하기 위해서 마스터-슬레이브 구조를 갖는 멀티 프로세서 구성을 이용한 항법 데이터 저장 시스템을 설계 제작하였다.

• Geomechanics and Engineering
• /
• v.24 no.3
• /
• pp.281-293
• /
• 2021

Uncertainties in geomechanical input parameters which mainly related to inappropriate data acquisition and estimation due to lack of sufficient calibration information, have led wellbore instability not yet to be fully understood or addressed. This paper demonstrates a workflow of employing Quantitative Risk Assessment technique, considering these uncertainties in terms of rock properties, pore pressure and in-situ stresses to makes it possible to survey not just the likelihood of accomplishing a desired level of wellbore stability at a specific mud pressure, but also the influence of the uncertainty in each input parameter on the wellbore stability. This probabilistic methodology in conjunction with Monte Carlo numerical modeling techniques was applied to a case study of a well. The response surfaces analysis provides a measure of the effects of uncertainties in each input parameter on the predicted mud pressure from three widely used failure criteria, thereby provides a key measurement for data acquisition in the future wells to reduce the uncertainty. The results pointed out that the mud pressure is tremendously sensitive to UCS and SHmax which emphasize the significance of reliable determinations of these two parameters for safe drilling. On the other hand, the predicted safe mud window from Mogi-Coulomb is the widest while the Hoek-Brown is the narrowest and comparing the anticipated collapse failures from the failure criteria and breakouts observations from caliper data, indicates that Hoek-Brown overestimate the minimum mud weight to avoid breakouts while Mogi-Coulomb criterion give better forecast according to real observations.

• Restorative Dentistry and Endodontics
• /
• v.31 no.5
• /
• pp.371-377
• /
• 2006

The purposes of this study were to assess the accuracy of measurements in pre-enlarged canals with small instruments and to compare the accuracies, in enlarged canal, with small size instruments and instruments that match the actual canal diameter using Root ZX, Bingo1020, SmarPex, and e-Magic Finder. Ten extracted teeth were embedded in an alginate model made for testing apex locators. A size 10 file was placed into the root canal until the tip of the file reached the plane of the major diameter of the foramen under a dental operating microscope at the 25 x magnification. The measurement was done with digital caliper and defined as actual length. Electronic length measurement with a size 10 file in pre-enlarged canal was done by reading the index indicating Apex of each device to gain a definite value After completion of canal enlargement to a size 45 file, each difference between actual length and electric measurement value with a size 10 and 40 files in enlarged canal was recorded as L10 and L40. The one-way ANOVA and Scheffe's multiple range tests were computed for analyze the differences among the four apex locators in the same group. The Student's t-test between L10 and L40 of each locator was done. The accuracies of electronic measurements were significantly different among the 4 devices. The file size made no difference on the accuracy of electronic measurement in enlarged canal with same device. The e-Magic Finder was the most accurate device among the 4 apex locators used in this study.