• 한국전기전자재료학회논문지
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• 제24권12호
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• pp.982-987
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• 2011

In this study, $Ge_8Se_{(2+x)}Te_{(6-x)}$ thin film amorphous-to-crystalline phase-change rate was evaluated in using a nano-pulse scanner. The focused laser beam with a diameter <10 ${\mu}m$ was illuminated in the power (P) and pulse duration (t) ranges of 1-31 mW and 10-460 ns, respectively, with subsequent detection of the responsive signals reflected from the film surface. We also evaluated the material characteristics, such as optical absorption and energy gap, crystalline phases, and sheet resistance of as-deposited and annealed films. The result of experiments showed that the thermal stability of the Ge-Se-Te film is largely improved by adding Se.

• 치과방사선
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• 제27권2호
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• pp.83-90
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• 1997

This study was performed to demonstrate the effect of linear or nonlinear contrast enhancement on subtraction images. Three different textures were radiograped on dental film. The first radiograph was taken without the presence of an object. the second, which showed trabucular bone, was taken of the molar area of a human. the third radiograph was taken of the coronal part of molars. Each film was digitized into a 1312 x 1024 pixel x 8 bit depth matrix by means of a Nikon 35 mm film scanner(LS-3510AF, Japan) with fixed gain and internal dark current correction to maintain constant illumination. The scanner was interfaced to a Macintosh Le ill computer(Apple Computer, Charlotte, N.C) This resulted in three pairs of images, including different textures-plain, bone and enamel. Digital regular, linearly and nonlinearly enhanced subtraction was performed. Computer software was ,used to simulate lesions in the shape of a 2D-Gaussian curve on each of a pair of images. The each subtraction images were presented in a random sequence to two groups of 10 observers(students and dentists). ROC analysis was used to compare observer performance. The following results were obtained ; 1. All of LCE subtraction, equalized subtraction and regular subtraction images of plain texture were diagnosed the best by far. 2. The data revealed a siginificant LCE effect in both the student group and the expert group. 3. Clinical expertise was a helphul factor for the observers in this study.

• 한국전기전자재료학회논문지
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• 제23권3호
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• pp.199-205
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• 2010

The crystallization speed (v) of amorphous (InTe)$_x$(GeTe) (x = 0.1, 0.3 and 0.5) films and their thermal, optical and electrical behaviors have been investigated using nano-pulse scanner (wavelength = 658 nm, laser beam diameter < 2 ${\mu}m$), X-ray diffraction (XRD), 4-point probe and UV-vis-IR spectrophotometer. These results were compared with those of $Ge_2Sb_2Te_5$ (GST) film, comprehensively utilized for phase-change random access memory (PRAM). Both v-value and thermal stability of (InTe)$_{0.1}$(GeTe) and (InTe)$_{0.3}$(GeTe) films could be enhanced in comparison with those of the GST. Contrarily, the v-value in the (InTe)$_{0.5}$(GeTe) film was so drastically deteriorated that we could not quantitatively evaluate it. This deterioration is thought because amorphous (InTe)$_{0.5}$(GeTe) film has relatively high reflectance, resulting in too low absorption to cause the crystallization. Conclusively, it could be thought that a proper compositional (InTe)$_x$(GeTe) films (e.g., x < 0.3) may be good candidates with both high crystallization speed and thermal stability for PRAM application.

• Nuclear Engineering and Technology
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• 제42권6호
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• pp.670-679
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• 2010

In this paper, a new approach using a pixel-based correction method was developed to fix the non-uniform responses of flat-bed type scanners used for radiochromic film dosimetry. In order to validate the method's performance, two cases were tested: the first consisted of simple dose distributions delivered by a single port; the second was a complicated dose distribution composed of multiple beams. In the case of the simple individual dose condition, ten different doses, from 8.3 cGy to 307.1 cGy, were measured, horizontal profiles were analyzed using the pixel-based correcton method and compared with results measured by an ionization chamber and results corrected using the existing correction method. A complicated inverse pyramid dose distribution was made by piling up four different field shapes, which were measured with GAFCHROMIC$^{(R)}$EBT film and compared with the Monte Carlo calculation; as well as the dose distribution corrected using a conventional method. The results showed that a pixel-based correction method reduced dose difference from the reference measurement down to 1% in the flat dose distribution region or 2 mm in a steep dose gradient region compared to the reference data, which were ionization chamber measurement data for simple cases and the MC computed data for the complicated case, with an exception for very low doses of less than about 10 cGy in the simple case. Therefore, the pixel-based scanner correction method is expected to enhance the accuracy of GAFCHROMIC$^{(R)}$EBT film dosimetry, which is a widely used tool for two-dimensional dosimetry.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.167-168
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• 2011

• 한국레이저가공학회지
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• 제17권3호
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• pp.19-23
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• 2014

To directly engrave circuit-line patterns as wide as $6{\mu}m$ in a buildup film to be used as an IC substrate, we applied a projection ablation technique in which an 8 inch dielectric ($ZrO_2/SiO_2$) mask, a DPSS 355nm laser instead of an excimer laser, a ${\pi}$-shaper and a galvo scanner are used. With the ${\pi}$-shaper and a square aperture, the Gaussian beam from the laser is shaped into a square flap-top beam. The galvo scanner before the $f-{\theta}$ lens moves the flat-top beam ($115{\mu}m{\times}105{\mu}m$) across the 8 inch dielectric mask whose patterned area is $120mm{\times}120mm$. Based on the results of the previous research by the authors, the projection ratio was set at 3:1. Experiments showed that the average width and depth of the engraved patterns are $5.41{\mu}m$ and $7.30{\mu}m$, respectively.

• 치과방사선
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• 제27권1호
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• pp.17-24
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• 1997

The purpose of the present study was to use digital profile image features and digital image analysis of fixed-dimension bone regions, extracted from standardized periapical radiographs of the maxilla, to determine whether differences exist in alveolar bone of younger women(mean age: 59.23±7.34 years) and just menopaused women(mean age: 59.23±7.34). Periapical films were used from two groups of 20 randomly selected women. None of the subjects had a remarkable medical history. To simplify protocol, we chose one interproximal bone area between the maxillary right canine and lateral incisor for study. Ech film was digitized into a 1312 x 1024 pixel x 8 bit depth matrix by means of a Nikon 35 mm film scanner(LS-35lOAF, Japan) with fixed gain and internal dark current correction to maintain constant illumination. The scanner was interfaced to a Macintosh LC III computer(Apple Computer, Charlotte, N.C.). Area and profile orientation were selected with a NIMH Image 1.37(NIH Research Services Branch, Bethesda, Md.). Histogram features were extracted from each profile and area. The results of this study indicate that mean pixel intensities didn't differ significantly between two groups and there was a high correlarion-coefficient between digitized radiographic profile features and area features.

• 대한방사선치료학회지
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• 제16권2호
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• pp.33-41
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• 2004

목적 : 선형가속기의 정도관리 항목 중 광조사야와 방사선조사야의 일치성 검사는 기존에 필름을 이용하여 측정하였다. 하지만 필름을 이용한 측정은 측정관찰자에 따라 오차가 크게 발생하여 이를 개선하기 위해 BIS(Beam Image System) 영상장치를 이용하여 필름과 조사야 일치성을 비교평가 하고자 하였다. 대상 및 방법 : 선형가속기를 이용하여 필름과 BIS 영상장치에 6, 15MV의 광자선을 조사하여 측정하였다. 조사야는 각각 $50{\times}50,\;100{\times}100,\;200{\times}200mm^2$지었고, 갠트리 각도는 필름을 사용시 $0^{\circ}$에서 측정하였고, BIS 영상장치를 사용시에는 $0^{\circ}$와 $270^{\circ}$에서 측정하였다. 그리고 조사야 일치성 측정은 필름을 사용시 눈금자와 필름 스캐너를 이용하였고, BIS 영상장치에서는 스캔된 광조사야와 방사선조사야의 폭을 X축과 Y축으로 각각 측정하여 그 오차값을 구하였다. 결과 : 필름을 이용한 관찰자의 시각적인 측정에서는 광조사야보다 방사선조사야가 더 크게 측정되었으며, 최대 1.9mm의 오차값을 보였다. 필름 스캐너를 이용한 측정에서도 방사선조사야가 더 크게 측정되었으며, 평균 오차값의 크기는 더 작은 값을 보였다. BIS 영상장치를 이용한 측정에서는 필름 사용시와는 반대로 갠트리 $0^{\circ}$와 $270^{\circ}$에서 광조사야가 방사선조사야보다 더 크게 측정되었고, 최대 0.96mm의 오차값을 보였다. ${\Delta}X$, Y축 모두 허용오차의 범위는 $<{\pm}2mm$로 나타났다. 측정된 평균 ${\Delta}X$, Y 오차값은 시각적인 필름측정, 필름스캐너 측정, BIS 순으로 작게 나타났다. 결론 : 본 연구의 측정결과, 필름을 이용한 시각적인 조사야 일치성 평가시에는 관찰자에 따른 측정오차의 값이 크게 나타날 수 있으므로 정확한 정도관리를 위해서는 세심한 주의로 측정할 것과 필요하다면 다른 영상장치의 도움이나 측정도구의 개발로 정확한 측정이 필요하다 하겠다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1158-1159
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• 2009

Tri-stimulus values of CIE-XYZ and RGB values obtained by photographic film, CCD camera or scanner depend on the spectral sensitivity of imaging devices and the spectral radiant distribution of the illumination. It is important to record and reproduce the reflectance spectra of the object for true device independent color reproduction and high accurate recording of the scene. In this paper, a method to record the reflection spectra of the object is introduced and its application to spectral endoscopes is presented.

• Journal of information and communication convergence engineering
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• 제5권2호
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• pp.116-120
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• 2007

In this paper, the image sensor using the a-Si:H TFT is proposed. The optimum amorphous silicon thin film is deposited using plasma enhanced chemical vapor deposition (PECVD). TFT and photodiode both with the thin film are fabricated and form image sensor. The photodiode shows that $I_{dark}\;is\;{\sim}10^{-13}\;A,\;I_{photo}\;is\;{\sim}10^{-9}\;A\;and\;I_{photo}/I_{dark}\;is\;{\sim}10^4$, respectively. In the case of a-Si:H TFT, it indicates that $I_{on}/I_{off}\;is\;10^6$, the drain current is a few ${\mu}A\;and\;V_{th}\;is\;2{\sim}4$ volts. For the analysis on the fabricated image sensor, the reverse bias of -5 volts in ITO of photodiode and $70 {\mu}sec$ pulse in the gate of TFT are applied. The image sensor with good property was conformed through the measured photo/dark current.