• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.477-481
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• 2012

An X-ray diffractometer which has various X-ray optics can give qualitative and quantitative information for a sample using a nondestructive analysis method. A parallel beam optic passes the parallel beam and removes divergent beam generated from an X-ray tube. The parallel beam optic used in the X-ray diffractometer was fabricated by wire cut and grading of stainless steel plates and was evaluated its performance using an X-ray imaging system. The measured parallelization of 6.6 mrad for the fabricated the parallel beam optic was a very close to the expected value of 6 mrad. An X-ray imaging technique for evaluating the parallel beam optics can estimate parallelization for each plate and can be used to other X-ray optics.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.234-239
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• 2008

Tungsten and rhodium target tube for a 40 kV x-ray transmission anode was developed to apply to the hand-held XRF(X-Ray Fluorescence) apparatus and its characteristics were evaluated. From the measurement of the energy distribution and dose of x-ray, it was confirmed that our results were good agreements with the known ones. The optimum thickness of metal film deposited on Be window to extract the maximum dose were $2.6{\mu}m$ and $2.7{\mu}m$ in case of W-target tube and Rh-target tube, respectively. When it was continuously worked during 30 min. at 40 kV in tube voltage and at $60{\mu}A$ in tube current, the temperature at target did not exceed $50^{\circ}C$. Our results reveals that the 40 kV x-ray transmission anode tube can be applied to the hand-held XRF apparatus.

• The Journal of the Korean dental association
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• v.58 no.3
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• pp.140-151
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• 2020

Purpose: To evaluate reliability of Q-ray view (Aiobio Inc,. Seoul, Korea) for assessing retention status of pit and fissure sealants. Methods: Pit and fissure sealants of 58 permanent molars from 15 third-grade students were examined. Posterior teeth with ≥1 pit and fissure sealants applied to the occlusal surface for >6 months were examined. The teeth were examined using traditional visual-tactile assessments and combined Q-ray view. Pit and fissure sealants were evaluated by assessing marginal plaque, marginal discoloration, marginal integrity, retention, and presence of caries. Fleiss kappa and Cohen's kappa values were calculated to compare inter- and intrarater agreements between visual-tactile and combined Q-ray view assessments. Results: Regarding interrater agreement in visual-tactile assessments, K values of Cohen's kappa for marginal plaque, marginal discoloration, and presence of caries were 0.22-0.57, 0.36-0.57, and 0.43-0.61, respectively, and agreements ranged from slight to moderate. When combined with Q-ray view, the values were 0.81-0.89, 0.69-0.88, and 0.80-0.90, respectively, and agreements ranged from substantial to nearly perfect level, indicating statistical significance. Marginal plaque (0.81-0.83), marginal discoloration (0.57-0.89), and presence of caries (0.69-0.91) showed higher agreements in combined Q-ray view than in visual-tactile assessments, and kappa values of marginal plaques were significantly higher in combined Q-ray view than in visual-tactile assessments. Conclusion: Evaluating retention status of pit and fissure sealants using Q-ray view showed higher reliability than using visual/tactile assessments for marginal plaque, marginal discoloration, and presence of caries. Therefore, Q-ray view may be used to assess the retention status of pit and fissure sealants.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.262-266
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• 2013

A new concept of periapical radiography, intra oral x-ray tube and detector system is introduced. It is new system that a miniature x-ray tube is inserted into mouse and it acquired digital image using external detector. In this study, we have investigated temperature and dose distribution of insertional x-ray tube for periapical radiography. To analyze temperature characteristic of x-ray tube, we attached the thermocouple to surface of x-ray tube and we measured the temperature according to distance. Also, we measured the dose distribution of a miniature x-ray tube according to distance. As a result, temperature was constant to $27^{\circ}C$ over 2mm without cooling system, dose distribution of x-ray tube was 3.14 and 1.84mGy in 3 and 5cm, respectively. Therefore, the proposed x-ray system works in lower dose than conventional dental x-ray system. Thus, it is considered that new concept of system will have a significant effect on medical imaging technology.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.77-80
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• 2004

In this study, the purpose is to verified the feasibility to develope Hybrid x-ray detector in order to resolve problems of direct and indirect x-ray detectors. The properties of X-ray detector depend on absorption of X-ray, charge generation by x-ray photon, leakage current. In this study, CdS was used as photoconductor, and $Y_2O_2S:Tb$ as x-ray phosphor was formed on CdS in order to embody Hybrid structure. And Screen printing was used to form Muli-layer. Characteristics of this specimen were analyzed by using SEM, and XRD. And Photoluminescence spectrum of $Y_2O_2S:Tb$, leakage current, with respect to applied voltages, output charge with respect to applied voltages, and X-ray sensitivity were measured. Also, linearity with respect to dose was measured. Leakage current was similar with direct digital x-ray detector, but sensitivity of the hybrid structure is much better than the single-layer structure.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.23-26
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• 1997

In exposuring x-rays, we can adjust three variables of kVp, mA and sec. The kVp is one of main factors affecting x-ray quality -peneterability. And miliampere-seconds is directly proportional to x-ray quantity. In this paper, we detected voltage variation of CdS, II-VI group semiconductor compounds, by kVp as the fundamental experiments of designing x-ray dosimeter. We exposured x-ray on the material from 40 to 100 kVp by increasing 2kVp using Shimadazu TH-500-125 Radio-Tex cx-s x-ray machine. We fixed miliampere -seconds to 100mA and 0.2 sec. After acquiring the raw data, we plotted the graph of kVp and voltage variation and figured slope value of 0.093 by regression. The standard deviation of voltage to kVp was 0.22. For the future study, the mAs variation study will be needed to investigate the connections between kVp and mAs in order to design x-ray dosimeter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.125-131
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• 2006

The existing X-ray generators are either ones which are settled at fixed places or ones which are movable to sick rum. Movable generators can be very useful according to the circumstances of patients, but there remains a restraint that AC220[V] in the hospitals must be provided. When examining a first-aid patient who stays distant from the hospital or when grouping patients caused by disaster, the services of doctors at emergency centers should be very restrictive. Hence, this study developed a portable digital X-ray power supply unit that are utilizable at the accident spot or in a moving ambulance. By using the nit, the information of patients can be transmitted to the emergency center on the spot and thereby doctors can make a correct diagnosis. The properties of the unit are as follows: First, portable batteries(DCl2[V]) are utilized as electric source for the wit. Second PIC16F84A is utilized as control circuit in order to guarantee considerable reliance and to provide various functions. This portable digital X-ray power supply unit is expected to contribute to the emergency medical service system to be more advanced.

• Journal of the Korean Wood Science and Technology
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• v.37 no.6
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• pp.531-536
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• 2009

Radial variations of ray spacing and frequency of biseriate ray were examined in the woods of most commercially important Korean softwood species of Pinus koraiensis and Larix kaempferi. Ray spacing, or ray number per mm in cross section, averaged 4.6 and 9.0 in Pinus koraiensis and Larix kaempferi, respectively. Thus, rays of Larix kaempferi appeared to be more closely arranged than those of Pinus koraiensis. Ray spacing was the densest around pith, and then slowly decreased toward bark. In tangential section, biseriate ray frequency of Larix kaempferi was higher than that of Pinus koraiensis. Biseriate ray was designated, based on the number of cells of biseriate portion in vertical extent, as the type of B+1 (one cell high), B+2 (two cells high), and so on. The dominated type was B+1 in Pinus koraiensis but B+2 in Larix kaempferi. The biseriate ray types of B+3, B+4, and B+5 were occasionally found in earlywood. Interestingly, even B+6 and B+7 types were observed in Larix kaempferi. In conclusion, it was considered that ray spacing could be used for separating juvenile wood from adult wood. Also, characteristics of ray spacing and biseriate ray might be used for identifying these two species.

• Journal of the Korean Wood Science and Technology
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• v.15 no.2
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• pp.90-98
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• 1987

In the present paper I described the relations of wood ray indicators such as ray height, ray width, number of rays per $0.25mm^2$, ray spacing and fusiform ray height on the stem of Pinus koraiensis and Larix leptolepis grown at the Experiment Forest of Kangweon National University. The results may be summarized as follows. 1. The number of rays and ray spacing were generally decreased with the increase of ray height on the sample woods. 2. According to the tree species the patterns of varition of ray width with the increase of ray height were different, namely the relation between ray width and ray height showed some positive correlation on Pinus koraiensis and negative on Larix leptolepis. 3. It was recognized that the variation of fusiform ray height due to the increase of ray height indicated two patterns(the increasing, md constant regions) in sample woods. This boundary seemed to appear at six cells of ray height on Pinus koraiensis and ninc cells on Larix leptolepis. 4. The relation between fusiform ray height and number of rays had a negative correlation on Pinus koraiensis, but this tendancy was not obvious on Larix leptolepis. And ray spacing and ray width due to the increase of fusiform ray height were generally decreased. 5. On the whole the values of ray spacing and ray width became gradually larger in proportion to the increase of number of rays. 6. According to the increase of ray spacing the values of ray width also increased gradually. But this tendency was more clear on Pinus koraiensis than larix leptolepis.

• Restorative Dentistry and Endodontics
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• v.37 no.3
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• pp.160-164
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• 2012

Objectives: This study was aimed to investigate the methods to reduce operator's radiation dose when taking intraoral radiographs with portable dental X-ray machines. Materials and Methods: Two kinds of portable dental X-ray machines (DX3000, Dexcowin and Rextar, Posdion) were used. Operator's radiation dose was measured with an 1,800 cc ionization chamber (RadCal Corp.) at the hand level of X-ray tubehead and at the operator's chest and waist levels with and without the backscatter shield. The operator's radiation dose at the hand level was measured with and without lead gloves and with long and short cones. Results: The backscatter shield reduced operator's radiation dose at the hand level of X-ray tubehead to 23 - 32%, the lead gloves to 26 - 31%, and long cone to 48 - 52%. And the backscatter shield reduced operator's radiation dose at the operator's chest and waist levels to 0.1 - 37%. Conclusions: When portable dental X-ray systems are used, it is recommended to select X-ray machine attached with a backscatter shield and a long cone and to wear the lead gloves.