• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.17 no.1
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• pp.89-106
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• 1987

The author obtained individualized lateral cephalometric tomograms from 23 young adults (46 of left and right normal TMJ) with normal occlusion and 20 patients (14 of patient asymptomatic TMJ and 26 of patient symptomatic TMJ) with clicking and painful TMJ after the analysis of submental vertex view. Individualized lateral cephlometric tomogram analysis and TMJ space analysis were performed after tracing each film. All data from these analysis was recorded and statistically processed with CYBER computer system. 1. The results were obtained as follows. In submental vertex view, the mean condylar angulation of Rt. side in normal group was 20.348°±6.358°, Lt. side was 18.870°±7.777° and Rt. side in patient group was 19.350°±7.576° Lt. side was 17.750°±6.146° respectively. The mean condylar angulation of Rt. side was larger than Lt. side in normal and patient group. 2. When the mandible was moved from centric occlusion to centric relation, condylar position relating to the glenoid fossa was placed posteriorly and superiorly in normal TMJ group and patient symptomatic TMJ group. 3. In centric relation position, the proportion of anterior space to posterior space was 1.593 for normal TMJ group, 1.604 for patient asymptomatic TMJ group and 1.671 for patient symptomatic TMJ group. In centric occlusion position, 1.390 for normal TMJ group, 1.539 for patient asymptomatic TMJ group and 1.196 for patient symptomatic group. Normal TMJ group, patient asymptomatic TMJ group and patient symptomatic TMJ group and patient symptomatic TMJ group revealed significant difference in ∠C₂ measurement. (ANOVA-test, p<0.05) 5. Normal group and patient group revealed significant difference in Fh, ∠C₁and ∠C₂ measurement. (T-test, p<0.05) 6. There were strong positive correlation (0.8771) between Fp and Fm, and strong negative correlation (-0.9039) between ∠C₂ and ∠C₁ from the lateral cephalometric tomogram analysis.

• Journal of the Korean Society of Radiology
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• v.7 no.3
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• pp.245-249
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• 2013

Neutron sources from photonuclear reaction with 46-MeV electron linear accelerator at Research Reactor Institute, Kyoto University used for resonance energy measurement of natural tantalum. BGO($Bi_4Ge_3O_{12}$) scintillation detectors used for measurement of the prompt gamma ray from the natural tantalum sample. The BGO spectrometer was composed geometrically as total energy absorption detector. The electric signal from the spectrometer was analyzed for TOF(Time-of-Flight) spectrum which is used identification of neutron capture resonance energy. In this study, the neutron energy region is from 1 to 200 eV, because of strong X-ray effect produced photonuclear reaction in Ta target, the measurement was performed to below 1 keV energy region. The resonance energy was compared with the evaluated values(ENDF/B-VI, Mughabghab). All of the resonances from 4.28 ~ 200 eV were seen in the present measurement except 144.3 eV resonance.

• Journal of the Korean Society of Radiology
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• v.13 no.7
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• pp.941-946
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• 2019

Computed tomography (CT) has been increasing in frequency and indications for use in clinical diagnosis and treatment decisions. Multidetector CT has the advantage of shortening the inspection time and obtaining a high resolution image compared to a single detector CT, but has been pointed out the disadvantage of increasing the radiation exposure. In addition, when the low tube voltage is used to reduce the exposure dose in the CT, noise increases relatively. In the existing method, the method of finding the optimal image quality using the method of adjusting the parameters of the image reconstruction method is not a fundamental measure. In this study, we applied a double-tree complex wavelet algorithm and analyzed the results to maintain the normal signal and remove only noise. Experimental results show that the noise is reduced from 8.53 to 4.51 when using a complex oriented 2D method with 100kVp and 0.5sec rotation time. Through this study, it was possible to remove the noise and reduce the patient dose by using the optimal noise reduction algorithm. The results of this study can be used to reduce the exposure of patients due to the low dose of CT.

• Journal of the Korean Society of Radiology
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• v.9 no.1
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• pp.55-59
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• 2015

Research about the proton nuclear reaction is actively achieving on the proton therapy including material development of fusion reactor. The proton induced gamma ray energy(2754, 1386 keV) spectrum of 27Al(p,3p+n)24Na reaction was measured with 100 MeV high energy proton beam. The proton beam in the experiment was derived from 100 MeV proton linear accelerator in the KOMAC. We measured the gamma ray intensity ratio of the decay level from the energy spectrum. The previous results have been compared with the current result. Strength of measured gamma rays will provide very important information though decide high energy gamma radiation detection efficiency.

• Journal of the Korean Society of Radiology
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• v.3 no.4
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• pp.23-28
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• 2009

Monochromatic X-ray can make a medical image of high contrast under a low radiation dose and can be easily generated by combining an X-ray tube and a multilayer mirror. A W/C multilayer mirror was optimally designed for a characteristic X-ray generated from a X-ray tube with Mo target. The d-spacing and the thickness ratio in design parameters were determined under the maximum-reflectivity condition. Tolerances for deposition and alignment of the W/C multilayer mirror were calculated. Within a deposition tolerance of 0.2nm and a alignment tolerance of ${\pm}0.01^{\circ}$, 85% of the theoretical peak reflectivity could be achieved. A multilayer mirror can be widely used for making medical images because of generating high fluence monochromatic X-ray.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.329-334
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• 2018

Radon which is natural component of air is a colorless and odorless radioactive gas. Radon exposure can also occur from some building materials if they are made from radon-containing substances by breathing. In this study, The radiation dose of radon concentration was detected at 8 buildings of the A university during 3-month from June. 2017 to August. 2017. We detected indoor radon exposure at 8 building of the university and estimated annual effective dose. The radon concentration of Hall G and Hall F of the A university represented 81 and $14Bq/m^3$ respectively and average indoor radon concentration represented $41.63Bq/m^3$. Average effective dose was estimated 0.40 mSv/y, maximum effective dose was 0.78 mSv/y and minimum effective dose was 0.13 mSv/y respectively. University is the place that students spend the almost whole time. We suggest ventilation and appropriate management of a building, which could reduce the natural radiation exposure by radon concentration.

• Journal of the Korean Society of Radiology
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• v.12 no.4
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• pp.519-524
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• 2018

Chest examinations and mass chest examinations using the CR(computed radiography) System are frequently used clinically. a factor that degrades image quality in the acquisition process is the use of unused IPs long times. this paper addresses the estimation of winer filter and improved wiener filter to restoration of Chest CR images Experimental results show that the proposed method can reduce noise. in low noise variation image wiener method was excellent than improved method and the result was the opposite at high noise varience. the application of algorithms to chest CR images effectively eliminates noise. the classic Wiener filter was better than the improved method. Multiple patients examined during the process without any erase IP(image plate) process, The proposed algorithm determines that the images can be restored to a good quality and will help to read the images.

• Journal of the Korean Society of Radiology
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• v.13 no.7
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• pp.961-968
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• 2019

The purpose of this study was to evaluate the usefulness of cerebral angiography in each energy level by using dual energy technique in CT. Methods were performed on 15 DE images and SE images of CT angiography. For the analysis of images, mean value, standard deviation, SNR and CNR value were determined by setting ROI on MCA, brain parenchyma tissue, and back ground. As a result of concurrent visual evaluation with Likert 5 point scale, the clearest MCA image was confirmed at DE 40 keV and SE 120 kVp(p>0.05). The SNR value of the SE image was measured to be similar to the 40 keV energy level of the DE image. The low energy level image of 40 keV and 50 keV was measured with a high SNR and the contrast ratio was higher than that of the high energy image.

• Imaging Science in Dentistry
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• v.39 no.1
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• pp.7-11
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• 2009

Purpose: The purpose of this study was to assess the prevalence and radiographic characteristics of the nuchal ligament ossification on lateral cephalometric radiographs in Koreans. Subjects and Method: I review and interpreted the lateral cephalometric radiographs from 4,558 patients (1,857 males and 2,701 females, age range from 2 to 79 years) who visited the Kyungpook National University Dental Hospital from January 1, 2008 to February 3, 2009. I grouped the shapes of nuchal ligament ossification as round, rod-like, and segmented shape. And localized the ossification as the involvement of anterior cervical vertebral body. The data were analyzed by using chi-squared test with two-tailed and at a 5% significance level. Results: Among those who showed the nuchal ligament ossification, he mean age of the 143 males was 51.1 and that of the 97 females was 48.0 years. It as not observed completely below teens, and was observed 1% in twenties, 6.1% in thirties, 18.6% in forties, and 26.3% over fifties. It was significantly prevalent in older age group (P<0.01) and in males than females among the same age group (P<0.05). The shapes of nuchal ligament ossification were as follows in order of frequency: rod-like (49.2%), round (30.4%), and segmented (20.4%). The highest involvement of ossification as found at the level of C5 (67.9%), C4 (29.2%), C6 (22.9%), C3 (3.3%), C7 (2.9%), C2 (0.8%), and C1 (0.4%). Conclusion: The nuchal ligament ossifications on lateral cephalometric radiographs were showed as round, rod-like, or segmented shape. The nuchal ligament ossification is often observed after the age of 40 and is observed more frequently in males than females. The highest shape of nuchal ligament ossification was rod-like shape and the highest involvement of cervical spine was C5.

• Journal of the Korean Society of Radiology
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• v.11 no.4
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• pp.189-195
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• 2017

Radiation protection equipment has widely used to protect human body from radiations, for example X-ray and gamma ray. The material of the radiation protection equipment is mainly lead (Pb) which has brought out lead poisoning and pollution when the equipment is fallen into disuse. This problem makes research and development find new Pb-free materials for use of radiation protection. Manufacturing and evaluation processes for developing those material were carried out repletely until obtaining the performance of protection rate. In this study, combination possibility of shielding material was studied using Geant4 monte carlo simulation. X-ray tube under the same condition in the real measurement of the protection rate was simulated, and X-ray tube spectrum was obtained. The X-ray tube spectrum was applied to study on the protection rate and lead equivalent. The porosity effect was simulated, and was one of key factors to determine protection rate or lead equivalent in radiation protection sheet of Pb-free.