• 한국결정학회지
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• 제19권1호
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• pp.1-6
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• 2008

Dilithio-o-carborane과 dipenyl disulfide를 반응(反應)하여 a phenyl thiolated o-carborane compound가 얻어 졌으며 X-ray crystallography로 밝혀진 이 compound의 구조(構造)와 ab initio 및 density functional theory로 계산(計算)한 이 compound의 구조문(構造間)에 conformational similarity가 있음을 확인(確認)하였다.

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.216-223
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• 2017

In this work, linear and mass attenuation coefficients, effective atomic number and electron density, mean free paths, and half value layer and $10^{th}$ value layer values of barium-bismuth-borosilicate glasses were obtained for 662 keV, 1,173 keV, and 1,332 keV gamma ray energies using MCNP-4C code and XCOM program. Then obtained data were compared with available experimental data. The MCNP-4C code and XCOM program results were in good agreement with the experimental data. Barium-bismuth-borosilicate glasses have good gamma ray shielding properties from the shielding point of view.

• 대한방사선기술학회지:방사선기술과학
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• 제13권1호
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• pp.19-24
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• 1990

In appilcation of wide latitude HR-C film to chest x-ray examination, former x-ray diagnosis area is larger and diagnostic information has great deal of promotion. HR-C film is compare to former x-ray film is larger latitude and density level is small, reading is very easily. Especially, high estimate that is in characteristic curve linearity of toe part is good, contrast of low density made good shape and not good describe to overlap is diagnostic information increase mediastinum portion etc.

• 정보저장시스템학회논문집
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• 제1권1호
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• pp.78-83
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• 2005

The Blu-ray disc as a next generation high density optical medium uses an objective lens of high numerical aperture(NA 0.85) and blue laser in order to increase the recording density. The double layer is also useful for doubling the density. The spherical aberration of Blu-ray disc is very sensitive to the thickness of the disk because of high numerical aperture. This paper suggests a method to compensate the spherical aberration caused by the change of disk thickness, by using the Liquid Crystal lens instead of the Liquid Crystal panel. It was possible to develop both the LC panel generating the optical phase difference and LC lens changing the optical power. In this paper, we analyzed the aberration performance and a position sensitivity of the two type LC elements when the samples deviate from the optical axis of the objective lens. The results of applying this analysis show that the LC lenses rather than the LC panels have a significant assembling tolerance. The theoretical characteristics of the two elements are calculated and compared with the measurement data.

• 전기의세계
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• 제23권5호
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• pp.54-60
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• 1974

Proposals were mode on how to differentiate radiation effects in morphological phases of polyethylene and discussions were developed with the results obtained on a low density polyethylene, SOCAREX, specified by number average molecular weight; overbar Mn=5,400, density; 0.92, and degree of branch; 3.4/100 carbon atom, which was irradiated to Co$^{60}$ .gamma. ray at the dose rate of 0.5 Mrad/hr in ambient temperature under the pressure of 10$^{-5}$ Torr. or 1 atm. respectively. The effect to crystalline phase in possibly deduced from dose dependent variation of relative area between (110) and (200) peaks on X ray diffraction spectrum and that, the effects to amorphous phase can be understood through dose dependent relaxation behaviours of .betha. peak on internal friction characteristics of the specimen. The results obtained thus far indicate that, in crystalline phase, relative crystallinity shows a rather rapid decrease up to 20 Mrad with increasing dose, however, little change of crystallinity can be observed in the region between 20-200 Mrad, and degradation appears to be more predominant than crosslinking up to 60 Mrad. While in amorphous phase the indication also shows that degradation is only predominant up to 20 Mrad. Furthermore several correlations can be seen with amenable explanation between dose dependent behaviours observed in both phases.

• Clinical and Experimental Pediatrics
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• 제53권3호
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• pp.286-293
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• 2010

Peak bone mass is established predominately during childhood and adolescence. It is an important determinant of future resistance to osteoporosis and fractures to gain bone mass during growth. The issue of low bone density in children and adolescents has recently attracted much attention and the use of pediatric dual-energy X-ray absorptiometry (DXA) is increasing. The process of interpretation of pediatric DXA results is different from that of adults because normal bone mineral density (BMD) of children varies by age, body size, pubertal stage, skeletal maturation, sex, and ethnicity. Thus, an appropriate normal BMD Z-score reference value with Z-score should be used to detect and manage low BMD. Z-scores below -2.0 are generally considered a low BMD to pediatrician even though diagnoses of osteoporosis in children and adolescents are usually only made in the presence of at least one fragility fracture. This article will review the basic knowledge and practical guidelines on pediatric DXA based on the International Society for Clinical Densitometry (ISCD) Pediatric Official Positions. Also discussed are the characteristics of normal Korean children and adolescents with respect to BMD development. The objective of this review is to help pediatricians to understand when DXA will be useful and how to interpret pediatric DXA reports in the clinical practice for management of children with the potential to develop osteoporosis in adulthood.

• Imaging Science in Dentistry
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• 제33권1호
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• pp.21-26
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• 2003

Purpose: To investigate the characteristics of the newly marketed, Insight dental X-ray film. Materials and Methods: Kodak Ultraspeed (DF-58), E-speed, Agfa Dentus M2, and Kodak Insight (IP-21) films were radiographed using a Trophy intra-oral radiographic machine. 10 step exposure times were prepared and each step exposure was monitored using a FH 40G (ESM Eberline Instruments) dosimeter for each of the 4 types of intra-oral film. All films were manually processed and the radiographic densities at 6 sites of each processed film were measured, and the characteristic curves of each of the 4 types intra-oral films were created utilizing these dosimetric data and radiographic densities, based on ISO 5779. The film contrast, speed, and base plus fog density of Insight film were compared with those of the 3 other films examined in this experiment. Results : E-speed film showed greatest average gradients followed by Insight film. E-speed and Ultraspeed film showed great average gradients at low density levels. Insight film showed the fastest speed followed by E-speed, Dentus M2 and Ultraspeed film. Dentus M2 film showed greatest base plus fog density level followed by Insight film. Conclusion : Kodak Insight film showed fastest film speed with comparable film contrast on characteristic curve.

• 한국재료학회지
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• 제21권12호
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• pp.703-707
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• 2011

The electrochromic properties of tungsten oxide films grown by RF sputtering were investigated. Among the sputter parameters, first the $Ar:O_2$ ratios were controlled with division into only an $O_2$ environment, 1:1 and 4:1. The structure of each film prepared by these conditions was studied by X-ray diffraction, X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. The sputter-deposited tungsten oxide films had an amorphous structure regardless of the $Ar:O_2$ ratios. The chemical compositions, however, were different from each other. The stoichiometric structure and low-density film was obtained at higher $O_2$ contents. Electrochemical tests were performed by cyclic voltammetry and chronoamperometry at 0.05 M $H_2SO_4$ solutions. The current density and charge ratio was estimated during the continuous potential and pulse potential cycling at -0.5 V and 1.8 V, respectively. The film grown in a higher oxygen environment had a higher current density and a reversible charge reaction during intercalation and deintercalation. The in-situ transmittance tests were performed by He-Ne laser (633 nm). At higher oxygen contents, a big transmittance difference was observed but the response speed was too slow. This was likely caused by higher film resistivity. Furthermore, the effect of sputtering pressure was also investigated. The structure and surface morphology of each film was observed by X-ray diffraction and scanning electron microscopy. A rough surface was observed at higher sputtering pressure, and this affected the higher transmittance difference and coloration efficiency.

• 천문학회보
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• 제35권2호
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• pp.33.2-33.2
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• 2010

Galaxy clusters are known to be very bright in X-ray and contain a large number of X-ray point sources within the X-ray emission. However, due to the fluctuations of the X-ray emission, it is very difficult to detect faint X-ray sources and to extract accurately the photometric properties of the X-ray point sources in galaxy clusters. In addition, the most X-ray telescopes show spatially varying point spread function (PSF) and suffer from severe vignetting. The Chandra Archival Survey of Galaxy Clusters project is a wide-area ($\sim40deg^2$) survey of serendipitous Chandra X-ray sources in galaxy cluster fields, containing ~58,000 X-ray point sources in ~800 Chandra ACIS observations of ~600 galaxy clusters. This project aim to investigate the density environmental effects on the physical properties of the X-ray point sources, comparing physical properties of the X-ray point sources in galaxy clusters to those in typical fields. To utilize the sensitivity and detection probability of the X-ray point sources in galaxy clusters, we perform extensive Monte-Carlo simulations. In this poster, we compare the detection probability of the X-ray point sources in galaxy clusters to that of typical fields, and discuss quantitatively the difference between them.

• 대한방사선기술학회지:방사선기술과학
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• 제20권2호
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• pp.34-43
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• 1997

There are 4 types of equipment in diagnostic radiography. These are single phase, three phase, inverter type and condenser type X-ray generators. It is very confusing to make an adequate exposure factor and to know the usage of different type of X-ray generators. In this experiment, I explored a comparative study of outputs in 4 different type of X-ray units. I expect that this experiment could be helpful for manufacturer to make both the X-ray equipment better, In terms of Ideal exposure factors, thereby reducing the patient dose. Experimental results are as follow : 1) X-ray output The ratio of X-ray output of single, three phase and inverter type of X-ray generator was 1 : 1.6 : 2 without absorber and 1 : 2 : 2.6 with 20 mm aluminium absorber. 2) Beam quality The X-ray beam quality of single phase generator was proved to be softer than three phase and inverter type of generators by 0.4 mmAL and 0.55 mmAl HVL respectively. 3) Reproducibility Linearity of X-ray output Retroducibility of X-ray output met the regulation below CV 0.05 and linearity also met the regulation below 0.1 in 4 types of diagnostic X-ray generators. 4) The comparison of incident dose Three phase X-ray generator was 20% higher than two other X-ray generators in radiation dose to make same film density.