• Imaging Science in Dentistry
• /
• v.31 no.1
• /
• pp.23-34
• /
• 2001

Purpose : To develop a new subtraction program for registering digital periapical images based on the correspondence of anatomic structures. Materials and Methods: The digital periapical images were obtained by Digora system with Rinn XCP equipment after translation of 1-16 mm, and rotation of 2-20° at the premolar and molar areas of the human dried mandible. The new subtraction program, NIH Image program and Emago/Advanced program were compared by the peak-signal-to noise ratio (PSNR). Results : The new subtraction program was superior to NIH Images program and Emagol Advanced program up to 16 mm translation and horizontal angulation up to 4°. Conclusion: The new subtraction program can be used for subtracting digital periapical images.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.14 no.4
• /
• pp.249-255
• /
• 2014

We present a simple method to watermark three-dimensional (3D) triangular meshes that have been generated from the depth data of the Kinect sensor. In contrast to previous methods, which maintain the shape of 3D triangular meshes and decide the embedding place, requiring calculations of vertices and their neighbors, our method is based on selecting one of the coordinate axes. To maintain shape, we use discrete wavelet transform and constant regularization. We know that the watermarking system needs the information to be embedded; we used a text to provide that information. We used geometry attacks such as rotation, scales, and translation, to test the performance of this watermarking system. Performance parameters in this paper include the vertices error rate (VER) and bit error rate (BER). The results from the VER and BER indicate that using a correction term before the extraction process makes our system robust to geometry attacks.

• Advanced Composite Materials
• /
• v.17 no.3
• /
• pp.301-317
• /
• 2008

The energy release rate associated with crack growth in adhesive double cantilever beam (DCB) specimens, including the effect of residual stresses, was formulated using beam theory. Because of the rotation of the asymmetric arms in the adhesive DCB specimens due to temperature change, it is necessary to correct the evaluated fracture toughness of the DCB specimens, specifically in the case of a large temperature change. This study shows that the difference between the true toughness and an apparent toughness due to the consequence of ignoring residual stresses can be calculated for a given specimen geometry and thermo-mechanical properties (e.g. coefficient of thermal expansion). The calculated difference in the energy release rates based on the present correction method is compared with that from FEM in order to verify the present correction method. The residual stress effects on the evaluation of the adhesive fracture toughness are discussed.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.20 no.3
• /
• pp.376-383
• /
• 2017

This paper describes the gyroscopic stability and the drag characteristics of the smart munition with a course correction fuze(CCF). A ballistic analysis was conducted to figure out the effect of the canards on the gyroscopic stability of the projectile. The analysis used the commercial ammunition performance evaluation software: Projectile Design and Analysis System(PRODAS). In particular, we compared the PRODAS analysis results to real field test results to investigate the influence of the CCF mounted projectile. In addition, some ballistic simulations were carried out to provide the conditions suitable for wind tunnel tests. Experimental results show that the added drag force by the canards is almost uniform regardless of the Mach number when the projectile is at the normal position where the angle of rotation and the angle of attack are both 0 degrees. However, as the angle of attack of the projectile increases, the additional drag force depends on the deflection of the canards.

• Journal of Institute of Control, Robotics and Systems
• /
• v.12 no.8
• /
• pp.824-833
• /
• 2006

In this paper, the image modelling of road's lane markings is established using view frustum(VF) model. From this model, a measurement system of lane markings and obstacles is proposed. The system also involve the real time processing of the 3D position coordinate and the distance data from the camera to the points on the 3D world coordinate by virtue of the camera calibration. In order to reduce their measurement error, an useful algorithm for which analyze the geometric variations due to traveling vehicle's fluctuation using VF model is proposed. In experiments, without correction, for instance, the $0.4^{\circ}$ of pitching rotation gives the error of $0.4{\sim}0.6m$ at the distance of 10m, but the more far distance cause exponentially the more error. We con finned that this algorithm can be reduced less than 0.1m of error at the same condition.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.04b
• /
• pp.802-804
• /
• 2004

현재 연구되고 있는 대부분의 홍채인식 기술은 홍채영역 추출 시, 획득된 눈 영상의 기울기가 일정하다는 가정에 기초하고 있다. 그러나 머리가 일정한 기울기를 가지고 있지 않다면 인식률의 저하를 가져오게 된다. 본 논문에서는 이 문제를 보완하기 위한 방안으로, PCA를 이용하여 분산이 최대가 되는 방향을 구하고 이를 기준으로 홍채데이터를 추출하는 방법을 제안한다. 본 논문에서는 우리가 제안하는 방법을 사용하여 실제 다양한 기울기로 취득한 모든 눈 영상에 대한 실험을 한 결과, 98.97%의 인식률을 얻어 비교적 일정한 홍채영역을 추출할 수 있음을 입증하였다.

• PNF and Movement
• /
• v.21 no.3
• /
• pp.337-344
• /
• 2023

Purpose: The purpose of this study was to evaluate changes in the lower extremity kinematics of subjects with dynamic knee valgus after we applied non-elastic tape while they performed overhead squat. Methods: Twenty-five subjects (12 females, 13 males) with dynamic knee valgus participated in this study. Hip and knee joint kinematics and medial knee displacement were measured during overhead squat with and without hip correction taping. Results: Hip joint internal rotation, knee valgus, and medial knee displacement were significantly lower during overhead squat with hip correction taping than without hip correction taping, but there was no significant difference in hip joint flexion and abduction. Conclusion: Hip joint correction using non-elastic taping is recommended to subjects with dynamic knee valgus to improve their lower extremity movement and alignment during overhead squat.

• Progress in Medical Physics
• /
• v.7 no.1
• /
• pp.65-77
• /
• 1996

Using the 2-D and 3-D Hoffman brain phantom, 3-D Jaszczak phantom and Single Photon Emission Computed Tomography, the effects of data acquisition parameter, attenuation, noise, scatter and reconstruction algorithm on image quantitation as well as image quality were studied. For the data acquisition parameters, the images were acquired by changing the increment angle of rotation and the radius. The less increment angle of rotation resulted in superior image quality. Smaller radius from the center of rotation gave better image quality, since the resolution degraded as increasing the distance from detector to object increased. Using the flood data in Jaszczak phantom, the optimal attenuation coefficients were derived as 0.12cm$\^$-1/ for all collimators. Consequently, the all images were corrected for attenuation using the derived attenuation coefficients. It showed concave line profile without attenuation correction and flat line profile with attenuation correction in flood data obtained with jaszczak phantom. And the attenuation correction improved both image qulity and image quantitation. To study the effects of noise, the images were acquired for 1min, 2min, 5min, 10min, and 20min. The 20min image showed much better noise characteristics than 1min image indicating that increasing the counting time reduces the noise characteristics which follow the Poisson distribution. The images were also acquired using dual-energy windows, one for main photopeak and another one for scatter peak. The images were then compared with and without scatter correction. Scatter correction improved image quality so that the cold sphere and bar pattern in Jaszczak phantom were clearly visualized. Scatter correction was also applied to 3-D Hoffman brain phantom and resulted in better image quality. In conclusion, the SPECT images were significantly affected by the factors of data acquisition parameter, attenuation, noise, scatter, and reconstruction algorithm and these factors must be optimized or corrected to obtain the useful SPECT data in clinical applications.

• The korean journal of orthodontics
• /
• v.46 no.4
• /
• pp.253-265
• /
• 2016

In the present report, we describe the successful use of miniscrews to achieve vertical control in combination with the conventional sliding MBT$^{TM}$ straight-wire technique for the treatment of a 26-year-old Chinese woman with a very high mandibular plane angle, deep overbite, retrognathic mandible with backward rotation, prognathic maxilla, and gummy smile. The patient exhibited skeletal Class II malocclusion. Orthodontic miniscrews were placed in the maxillary anterior and posterior segments to provide rigid anchorage and vertical control through intrusion of the incisors and molars. Intrusion and torque control of the maxillary incisors relieved the deep overbite and corrected the gummy smile, while intrusion of the maxillary molars aided in counterclockwise rotation of the mandibular plane, which consequently resulted in an improved facial profile. After 3.5 years of retention, we observed a stable, well-aligned dentition with ideal intercuspation and more harmonious facial contours. Thus, we were able to achieve a satisfactory occlusion, a significantly improved facial profile, and an attractive smile for this patient. The findings from this case suggest that nonsurgical correction using miniscrew anchorage is an effective approach for camouflage treatment of high-angle cases with skeletal Class II malocclusion.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
• /
• v.20 no.2
• /
• pp.15-20
• /
• 2014

Objective: The purpose of this study was to investigate the effects of sling exercise on the cervical lordotic angle, craniovertebral angle, and head rotation angle among adolescents in the forward head posture. Methods: The subjects include 22 adolescents that recorded a mild level or higher on the posture evaluation index by New York State. They were randomly divided to the hand exercise group (n=11) and the control group (n=11). The former group participated in the sling exercise program three times a week over four weeks in total with each session lasting 60 minutes, whereas the latter group was not included in the program. The cervical lordotic angle, craniovertebral angle, and head rotation angle were measured before and after the intervention. Results: The study compared the cervical lordotic angle between the two groups before and after sling exercise and found that the sling exercise group made an increase of $7.36^{\circ}$ from $21.91^{\circ}$ to $29.27^{\circ}$ after the intervention(p<.05). As for the comparison results of the craniovertebral angle, the sling exercise group made an increase of $5.64^{\circ}$ from $48.91^{\circ}$ to $54.55^{\circ}$ after the intervention (p<.05). As for the comparison results of the cranial-rotation angle, the sling exercise group made an decrease of $-7.73^{\circ}$ from $148.82^{\circ}$ to $141.09^{\circ}$ after the intervention (p<.05). The control group showed no differences before and after the intervention (p>.05). Conclusion: Those findings indicate that the application of sling exercise in the forward head posture can be a good program to maintain the right posture and improve or prevent an abnormal posture and raise a need for more clinical applications and ongoing researches.