• Journal of the Optical Society of Korea
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• 제18권3호
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• pp.256-260
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• 2014

Columnar-structured cesium iodide (CsI) scintillators doped with thallium (Tl) are frequently used as x-ray converters in medical and industrial imaging. In this study we investigated the imaging characteristics of CsI:Tl films with various reflective layers-aluminum (Al), chromium (Cr), and titanium dioxide ($TiO_2$) powder-coated on glass substrates. We used two effusion-cell sources in a thermal evaporator system to fabricate CsI:Tl films on substrates. The scintillators were observed via scanning electron microscopy (SEM), and scintillation characteristics were evaluated on the basis of the emission spectrum, light output, light response to x-ray dose, modulation transfer function (MTF), and x-ray images. Compared to control films without a reflective layer, CsI:Tl films with reflective layers showed better sensitivity and light collection efficiency, and the film with a $TiO_2$ reflective layer showed the best properties.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1760-1768
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• 2022

When gamma-camera sensor modules, which are key components of radiation imagers, are derived from the coupling between scintillators and photosensors, the light collection efficiency is an important factor in determining the effectiveness with which the instrument can identify nuclides via their derived gamma-ray spectra. If the pixel area of the scintillator is larger than the pixel area of the photosensor, light loss and cross-talk between pixels of the photosensor can result in information loss, thereby degrading the precision of the energy estimate and the accuracy of the position-of-interaction determination derived from each active pixel in a coded-aperture based gamma camera. Here we present two methods to overcome the information loss associated with the loss of photons created by scintillation pixels that are coupled to an associated silicon photomultiplier pixel. Specifically, we detail the use of either: (1) light guides, or (2) scintillation pixel areas that match the area of the SiPM pixel. Compared with scintillator/SiPM couplings that have slightly mismatched intercept areas, the experimental results show that both methods substantially improve both the energy and spatial resolution by increasing light collection efficiency, but in terms of the image sensitivity and image quality, only slight improvements are accrued.

• 반도체디스플레이기술학회지
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• 제16권4호
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• pp.41-45
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• 2017

We have investigated the light extraction efficiency of large-area OLED lighting panels with a microlens array (MLA) or external scattering layer (ESL) by ray tracing simulation. The application of MLA and ESL to transparent OLEDs (TOLEDs) with an auxiliary metal electrode is also studied. It is found that MLA shows higher light extraction efficiency, compared with ESL. However, we have demonstrated that ESL is more suitable for TOLEDs having dual-sided equal light emission. Namely, equal light emission from the front and rear surfaces of TOLED can be achieved by increasing the scattering particle density of ESL. To compensate for a loss in light emission induced by auxiliary metal electrode, we come out with an OLED structure partially covered with MLA at the outer surface of glass substrate, which is aligned with metal electrode. With this scheme, it is observed that the light extraction efficiency can be boosted more than 20% from opaque OLED and 50% from transparent OLED.

• Journal of Astronomy and Space Sciences
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• 제15권1호
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• pp.1-26
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• 1998

The structure of the magnetic funnel element in the intermediate polar is con-sidered in terms of an important site for the X-ray absorption and the reemis-sion of the X-ray as the optical light. In this paper the column density and the optiacl depth vary with the filling factor, which is introduced to characterize the structure of matter in the magnetic funnel element. The results of the en-ergy dopendence of the X-ray spectrum and the modulation depth of the X-ray light curve are discussed.

• 한국가금학회지
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• 제42권2호
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• pp.125-132
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• 2015

원적외선은 자연계의 태양에너지의 한 부분으로 가시광선의 적색영역보다 파장이 월등히 길어서 열작용이 크며, 생체 내 침투력이 강한 파장으로 알려져 있다. 본 연구에서는 육계를 사육하는 과정에서 일정량의 원적외선을 조사하는 방법으로 육계의 건강 증진은 물론, 사육환경의 개선 효과의 가능성을 검정하고자 하였다. 세미브로(Ross ♂ ${\times}$ Hyline ♀) 암수 무감별추 200수를 공시하여 흰색조명, White구(5,000~5,700 K), 흰색조명+원적외선 조사(White+FIR구), 녹색조명, Green구(525~570 nm) 녹색조명+원적외선(Green+FIR구)의 4처리, 처리당 2반복으로 실험을 실시하였다. 전 사육기간 중 증체량과 사료효율은 녹색조명 환경이 백색조명 환경보다 높게 나타나는 경향이 인정되었다. 이러한 증가는 두 조명 모두 원적외선 조사에 의해서 더 증가되는 경향이 인정되었다. 사육장 바닥 깔짚 내 ammonia 및 저급탄화수소의 발생량은 조명의 색깔에 따른 차이는 인정되지 않았지만, 두 조명 모두 원적외선 조사에 의해서 ammonia 및 저급탄화수소의 발생량이 감소하는 경향이 인정되었다. 혈장 내 AST의 농도는 녹색조명 처리구가 백색조명 처리구보다 낮게 나타났으며, 이러한 경향은 두 조명 모두 원적외선의 조사에 의해서 더 감소되어서 백색조명 처리구보다 녹색조명에 원적외선을 조사한 처리구에서 유의하게 낮게 나타났다(P<0.05). 혈액 중 albumin 및 각종 면역 글로블린(LgA, lgG 및 lgM)의 농도는 조명의 차이에 따른 변화는 인정되지 않았지만, 흰색조명, 녹색조명 모두 원적외선 조사에 따라서 증가하는 경향이 나타났다. 결론적으로 육계 사육과정에 원적외선의 조사는 사육환경 개선 및 생리활성물질의 증가에 영향을 미쳐서 생산성을 증가시킬 가능성이 있다고 생각되어진다.

• 대한디지털의료영상학회논문지
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• 제13권4호
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• pp.157-164
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• 2011

This test is for checking investigation about quality control of general X-ray system in clinic and hospital. We compared general X-ray system of clinic and hospital which are selected freely in the metropolitan area using PMX-III and carried out quality control. Carried out Kilovoltage test, mR/mAs output test, Light filed/Beam alignment test, Half value layer test. Most of test result are appeared that failure rates of clinic is higher than hospital one. Therefore, we should lower failure rates through regular quality control and make environment which can get high quality image.

• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.65-69
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• 1989

Mather type dense plasma focus device was develooped for the feasibili쇼 study in its application to the x-ray lithography. To etermine the electrical characteristics,the temporal begavior of the discharge current and the voltage was measured by using the Rogowski coil and the high voltage probe respectively. The results are 9 $\mu\textrm{s}$ of the period, 18m$\Omega$ of resistance and 0.16$\mu$Η of inductance. The average current sheath velocity was measured by the light signal emitted at the moving plasma sheath. The light signal was detected through two fiber bundles. When the applied voltage was 13 kV and the initial jpressure of argon was 21.8 Pa, the best plasma focus was occurred. The x-ray emission characteristics from the plasma focus was determined by the x-ray pictures taken by pinhole camera. It is focus that the plasma was focused at 1.4 cm distant position above the center electrode and its diameter was about 1.0 m.

• 한국광학회지
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• 제3권2호
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• pp.86-91
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• 1992

Synchrotron 방사광으로 부터 soft X-ray, 광에너지 300-1200eV, 영역의 특정 파장을 선택할 수 있는 단색화 장치의 설계에 대하여 알아보았다. C.T.Chenㅡ이 새로운 제안에 의해 건설되어 그 성능이 기존의 여러 단색화 장치보다 우수하다고 알려진 Brookhaven National Laboratory의 CEM(cylindrical element monochromator) 형태인 Dragon beam line을 모델로 하여 PLS(Pohang Light Source) 방사광 가속기의 구조에 맞게 광학적 설계시 고려해야할 조건을 조사하였다.

• 대한의용생체공학회:의공학회지
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• 제28권2호
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• pp.306-309
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• 2007

PXLM(Phosphor based x-ray light modulator) has a combined structure by phosphor, photoconductor, and liquid crystal and it can realize x-ray image of high resolution in clinical diagnosis area. In this study, we fabricated a photoconductor and investigated electrical and optical properties to confirm application possibility of radiator detector of PXLM structure. As photoconductor, amorphous selenium(a-Se), which is used most in DR(Digital radiography) of direct conversion method, was used and for formation of thin film, it was formed as $20{\mu}m-thick$ by using thermal vacuum evaporation system. For a produced a-Se film, through XRD(X-ray diffraction) and SEM(Scanning electron microscope), we investigated that amorphous structure was uniformly established and through optical measurement, for visible light of 40 $0\sim630nm$, it had absorption efficiency of 95 % and more. After fabricated a-Se film on the top of ITP substrate, hybrid structure was manufactured through forming $Gd_2O_3:Eu$ phosphor of $270{\mu}m-thick$ on the bottom of the substrate. As the result to confirm electrical property of the manufactured hybrid structure, in the case of appling $10V/{\mu}m$, leakage current of $2.5nA/cm^2$ and x-ray sensitivity of $7.31nC/cm^2/mR$ were investigated. Finally, we manufactured PXLM structure combined with hybrid structure and liquid crystal cell of TN(Twisted nematic) mode and then, investigated T-V(Transmission vs. voltage) curve of external light source for induced x-ray energy. PXLM structure showed a similar optical response with T-V curve that common TN mode liquid crystal cell showed according to electric field increase and in appling $50\sim100V$, it showed linear transmission efficiency of $12\sim18%$. This result suggested an application possibility of PXLM structure as radiation detector.

• 한국재료학회지
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• 제19권10호
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• pp.555-561
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• 2009

Expanded graphite (EG) is synthesized by chemical intercalation of natural graphite (NG) and rapid expansion at high temperature, with titanium n-butoxide (TNB) used as titanium source by a sol-gel method to prepare EG-TiO$_2$ composite. The performances of the prepared EG-TiO$_2$ composite are characterized by BET surface area measurement, scanning electron microscopy (SEM), X-ray diffraction patterns (XRD) and energy dispersive X-ray analysis (EDX). To compare the photocatalytic activities of the EG-TiO$_2$ composite, three kinds of dye solutions, methylene blue (MB), methylene orange (MO) and rhodamine B (RhB), and two kinds of light source, UV light and visible light (VL), are used. Comparing the results, it can be clearly seen that the degradation of all of the dye solutions under irradiation by UV light is much better than that under irradiation by visible light, and the decomposition of MB solution was better than that of both of MO and RhB solution.