• Progress in Medical Physics
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• v.14 no.4
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• pp.249-258
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• 2003

A few years ago, a proposal was made to change the dosimetry from the air kerma-based reference dosimetry to the absorbed dose-based reference dosimetry for all radiotherapy beams of ionizing radiation to improve the accuracy of dosimetry. Here, we present a dosimetry study in which the two most widespread absorbed dose­based protocols (IAEA TRS­398 and AAPM TG­51) were compared with an air kerma­based protocol (IAEA TRS-277) by measuring the absorbed dose in the same reference depth. Measurements were performed in three clinical electron beam energies using a PTW 30002 cylindrical chamber, and Markus and Roos plane­parallel chambers. $^{60}$ Co calibration factors were obtained from the KFDA. The absorbed dose differences between the air kerma­based and absorbed dose­based protocols were within 2.0% for all chambers in all beams. The results thus show that the obtained absolute dose values will be not significantly altered by changing from the air kerma­based dosimetry to the absorbed dose­based dosimetry. It was also shown that absorbed dose values between the absorbed dose­based protocols agreed by deviations of less than 0.5% for a cylindrical chamber and less than 0.7% for plane­parallel chambers using cross­calibration factors. Although the use of a cylindrical chamber and plane­parallel chambers resulted in a difference of less than 2% for all situations investigated here, to reduce errors, the plane­parallel chambers are recommended for electron energies in which the use of cylindrical chamber is not permitted in each protocol.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.3
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• pp.6-12
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• 1984

The basic binary quantized first-order digital phase locked loop (DPLL) is modified in order to reduce the aquisition time and steadyftate phase error. Adding the loop that corrects the phase difference by detecting the falling zero-crossing time, an effort for the improving the performance is performed and the performance compared with that of the basic DPLL. Using a graphical method, the phase locking processes of the modified DPLL for a phase step and a frequency step input are depicted visually in the absence of noise. The performance of the modified DPLL for a sinusoidal input added narrow band random noise is evaluated using the Chapman-Kolmogorov equation. This approach is verified by direct computer simulation. The steady-state phase error and the average aquisition time of the modified DPLL are compared with those of the basic DPLL, It is shown that the aquisition time of the modified DPLL is shortened about twice, also, as signal to noise ratio increases, the effect of the modification increases and the steady-state phase error approaches to zero.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.4
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• pp.77-81
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• 2009

Purpose: To study the change of fixation disparity and accommodation as fusion contrast is deteriorated. Methods: 16 subjects who had above 20/20 and stereopsis took part. Monocular and binocular refraction were done with Zeiss Polatest Classic whereas the critical angle for stereopsis was done with TNO. A computer programmed with Random-Dot stereogram and vernier test managed a precise change of the fusion contrast and exposure time. Results: The fixation disparity was influenced by reduction of fusion contrast and had tendancy to exophoria (p=0.0004), especially it is considerably higher when uncrossed disparity was shown to exophoric subjects. Although accommodation was not influenced by a change of fusion contrast (p=0.803), vernier acuity was influenced (p=0.0000). Conclusions: Exophoric trend arose as the fusion contrast was reduced, nevertheless there was no accommadative change.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.6 no.1
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• pp.75-81
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• 2012

This study in the treatment of autistic horse therapy of children with disabilities that affect the perception of parents is to some extent how well treatment for a sense of purpose and a horse therapy was to evaluate the expectations. As parents of autistic children with disabilities a questionnaire study of 100 people was used as a research tool. Analysis of the frequency analysis method, Chi-square Analysis were analyzed by taking advantage of each. Parents interested in horse therapy and children who do not have the experience of riding. In addition, Parents who have children age 10-20 riding in the response was that there would be effects Understanding mainly ride horses in the horse therapy is physical exercise. And therapy and exercise that combines specific area of expertise, as is the way to help. In addition, behavior modification, and it is used as a way to improve. Expectations in the therapeutic horse therapy should be major(occupational therapy, physical therapy, speech therapy). Horse therapy is suitable for individual therapy at least for 2-3 weeks and the Confederacy.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.28-35
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• 2014

Osteochondroma is the most common benign bone tumor. The majority of osteochondromas (85%) present as solitary, nonhereditary lesions. In general, osteochondroma has no symptoms,however, facial asymmetry, malocclusion, crossbite and mouth opening can be occurred in case of temporomandibular joint involved. Radiologic analyses are indispensable element to diagnose osteochondroma and pathogenetic analysis showed that hereditary multiple osteochondromas are caused by mutations in either of two genes: exostosis(multiple)-1 (EXT1), which is located on chromosome 8q24.11 - q24.13 or exostosis(multiple)-2 (EXT2), which is located on chromosome 11p11 - 12. Recently, reduced mRNA of EXT1 was described in nonhereditary osteochondromas. The treatment of choice for osteochondroma is surgical unless the skeleton is still immature. Surgery associated with orthodontic treatment can be a valid approach to minimize facial asymmetry and malocclusion in case of temporomandibular with osteochondroma.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2D
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• pp.277-285
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• 2008

X-ray images are wildly used in medical applications, and these can be more efficiently find scoliosis which is appearing during the growth of human skeleton than others. This research is focused on the calibration of X-ray image and three-dimensional coordinate determination of objects. Three-dimensional coordinate of objects taken by X-ray are determined by two step procedure. Firstly, interior and exterior orientation parameters are determined by camera calibration using Primary Calibration Object (PCO) which has two sides with embedded radiopaque steel ball. Secondly, calibration cage coordinates which is composed of two acrylic sheets that are perpendicular to X-ray source are determined by the parameters. Three-dimensional coordinates of calibration cage determined by photogrammetric technique are compared with that of Coordinate Measuring Machine (CMM). Though the accuracy analysis, X direction which is parallel to X-ray source error values are relatively higher than those of Y and Z directions. But, the accuracies of Y and Z axis are approximately -3 mm to 3 mm. From the research results, it is considered that photogrammetric technique is applied to determine three-dimensional coordinates of patients or assist to make medical devices.

• The korean journal of orthodontics
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• v.25 no.3 s.50
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• pp.311-321
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• 1995

This study was undertaken to investigate the distribution of the chewing side preference and variations in the maximum bite force and facial morphology according to chewing side preference since unilateral chewing may cause morphologic and functional anomalies. 50 dental students who had no signs or symptoms of masticatory system and Angle's Class I relationship in posterior segments were selected, and divided into two groups, that is, 25 in bilateral chewing group(19 male and 6 female) and 25 in unilateral chewing group(10 male and 15 female). Maximum bite force was estimated ana posteroanterior cephalogram were measured ana statistically analyzed. The results were as follows : 1. Their were more students with bilateral chewing side preference($68\%$) and unilateral chewing side group consisted of right side preference($68\%$) and left side preference($32\%$). 2. There was no significant difference in the strength of max. bite force between the right and left side in bilateral chewing group. The bite force of the chewing side nab greater in the unilateral chewing group but less in the non-chewing side compared to those of bilateral chewing group with Bo significant difference. Max. bite force of chewing side was greater than that of non-chewing side in the unilateral chewing group(Female p<0.05). Max. bite force of males was about twice in that of females in both groups(p<0.05). Max. bite force of chewing side of the unilateral chewing group was similar to that of the bilateral chewing group, but that of non-chewing side was less than that of the bilateral chewing group. 3. In comparison of the facial morphology, there was no statistically significant difference in the size between the right and left side of the bilateral chewing group and between chewing and non-chewing side of the unilateral chewing group.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.385-390
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• 2016

ELoran Systems can provide Position, Navigation, and Time services with comparable performance to Global Positioning Systems (GPS) as a back up or alternative system. High timing and navigation performance can be achieved by eLoran signals because eLoran receivers use "all-in-view" reception. This incorporates Time of Arrival (TOA) signals from all stations in the service range because each eLoran station is synchronized to Coordinated Universal Time (UTC). Transmission station information and the differential Loran correction data are transmitted via an additional Loran Data Channel (LDC) on the transmitted eLoran signal such that eLoran provides improved Position Navigation and Timing (PNT) over legacy Loran. In this paper, we propose a technique for adapting the delay time compensation values in eLoran timing receivers to provide precise time comparison. For this purpose, we have designed a system that measures time delay from the crossing point of the third cycle extracted from the current transformer at the end point of the transmitter. The receiver delay was measured by connecting an active H-field, an E-field and a passive loop antenna to a commercial eLoran timing receiver. The common-view time transfer technique using the calibrated eLoran timing receiver improved the eLoran transfer time. A eLoran timing receiver calibrated by this method can be utilized in the field for precise time comparison as a GNSS backup.

• Journal of Chest Surgery
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• v.29 no.2
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• pp.177-184
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• 1996

Between 1987 and 1994, 21 patients were treated surgically for aortic aneurysm involving the thoracoabdominal aorta. There were 11 males and 10 females, and their age ranged from 20 to 67 years old and mean age was 41.5 years. Many complained of back pain, chest pain or discomfort, and flank pain, but three patients were asymptomatic. 15 patients had chronic dissection (71.4%) and 6 had nondissecting fusiform or saccular aneurysm(28.5%), and of those 15 patients with chronic dissection, 6(28.5%) had atherosclerosis assniated with hypertension, 5 (23.8%) were Martian syndrome, and 2 (9.5%) were associated with pregnancy. The diameter of an aneurysm ranged from 6cm to 12cm, and their extent was classified as type I in 7(33.3%), type II in 8(38.1%), type III in 3(14.3%), and type IV in 3(14.3%) patients based on Crawford classification for TAA . Diseased aorta was replaced with artificial vascular graft in all but one patient. In whom the aortic tear site due to pseudoaneurysm was closed by primary suture. For the spinal cord protection during the operation, we used partial cardiopulmonary bypass (FV-FA or PA-FA bypass) in 12 patients (57.1%), Biopump (LA-FA bypass) in 4(19.0%), total circulartory arrest and CPB in 2 (9.5%), Gott's heparinized shunt in 1(4.7%), and simple aortic cross clamping in 2 (9.5%). The most common complication after the operation was hoarseness due to unilateral vocal cord palsy which onured in 5 patients (23.8%), and the next common complication was wound infection in 4 patients(19.0%), paraplegia in 2 patients (9.5%), chylothorax in 1 patient(4.7%). The hospital mortality rate was 9.5% (2deaths), and there was no late death. Our experience shows that the graft replacement of TAAA had reasonable rate of mortality, low rate of serious complication, and provided good post operative state of the pati nts, and since the thoracoabdominal aortic operation is not a high risky procedure anymore, we recommend a radical operation for the indicated patients.

• The korean journal of orthodontics
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• v.32 no.4 s.93
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• pp.275-291
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• 2002

Of various factors indicated for effective use of straight wire appliances, there was a great lack of studies both domestic and international about the curvatures of tooth crowns. This study was performed to investigate the labio/buccal clinical crown curvatures of Korean permanent teeth. For this study, three-dimensional laser scanning was performed on 36 dental casts with normal anatomic structures. Andrews plane and Facial axis of clinical crown (FACC) were designated as horizontal and vertical reference planes respectively. 2 or 3 lines, 1mm apart, were drawn superior, inferior, left and right of these reference planes. A three-dimensional coordinate table was made for points formed by crossing these lines, and averages of each coordinate point on the 36 dental casts were obtained. The curvature equation was made using three-dimensional coordinate points (x,y,z) and by this curvature equation, the curve ratio of each tooth was obtained. Curve ratio changes of each section of teeth were calculated by curve ratios of simplified curves. These two dimensional curves were simplified horizontally and vertically Conclusions for this study are as follows. 1. The basic data of labial and buccal clinical crown curvatures were obtained about Korean permanent teeth. 2. No significant difference was found between male and females. 3. Individual tooth characteristics 1) In maxillary central incisors, the difference in the curve ratio between the gingival and incisal sides was greater than for the other teeth. And the gingival side showed a greater curve ratio. 2) Maxillary canines showed more curvatures in the mesio-occlusal surface than the other surfaces. 3) In maxillary $1^{st}$ premolars, more curvatures were found in mesio-occlusal and disto-gingival surface, thus showing a twisted crown surface, but in maxillary $2^{nd}$ premolars, the crown curvatures of mesial and distal ends became parallel to each other. 4) No significant difference in crown curvatures was found between mandibular central and lateral incisors. 5) Occluso-gingival curvatures of mandibular$2^{nd}$ premolar turned out to be more rounded than mandibular $1^{st}$ premolars or maxillary $2^{nd}$ premolars. From the above conclusions, it can be deduced that the same bracket bases can be used for mandibular central and lateral incisors. But for maxillary $1^{st}\;and\;2^{nd}$ premolars and for mandibular $1^{st}\;and\;2^{nd}$ premolars, because crown curvatures showed significant differences, when making bracket bases there is ample reason to make bracket base curves differently for each type of tooth.