• 한국진공학회:학술대회논문집
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• 한국진공학회 1998년도 제14회 학술발표회 논문개요집
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• pp.17-17
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• 1998

Synchrotron radiation is produced when charged particles moving with relativistic velocities a are accelerated - for example, deflected by the bending magnets which guide the electron or p positrons in circular accelerators or storage rings. By using special focusing magnetic lattices i in the particle accelerators it is possible to make the dimensions of the particle beam very small with a hi맹 charge density which results in a light source with high b디lIiance. Synchrotron light h has important properties which make it ideal for a wide range of investigations in surface s science. The fact that the spectrum of electromagnetic radiation emitted in a bending magnet e extends in a continuum from the 얹r infra red region to hard x-rays means that it is id않I for a v variety of spectroscopic studies. Since there are no convenient lasers, or other really bright l light sources, in the vacuum ultraviolet and soft x-ray re.밍ons the development of synchrotron r radiation has enabled enormous advances to be made in this di펌C비t spectr따 re밍on. P Polarization-dependent measurements, for ex없nple ellipsometry or circular dichroism studies a are possible because the radiation has a well-defined polarization - linear in the plane of orbit w with additional right-circular, or left-circular, components for emission an생es above, or below, t the horizontal, respectively. Since the synchrotron light is emitted from a bunch of charge c circulating in a ring the light is emitted with a well-defined time structure with a short flash of l light every time a bunch passes an exit port. The time structure depends on the size of the ring a and the number and sequence of filling of the bunches. A pulsed light source enables time¬r resolved studies to be performed which provide direct information on the lifetimes and decay m modes of excited states and in addition opens up the possibility of using time of flight t techniques for spectroscopic studies. The fact that synchrotron radiation is produced in a clean u ultrahi야 vacuum environment is of gr않t importance for surce science studies. The current t비rd generation synchrotron light sources provide exceptionally high baliance and stability a and open up possibilities for experiments which would have been inconceivable only a short time ago.

• 한국의학물리학회지:의학물리
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• 제33권4호
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• pp.158-163
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• 2022

Purpose: We subjected scanning electron microscopic (SEM) images of the active layer of EBT3 film to texture analysis to determine the dose-response curve. Methods: Uncoated Gafchromic EBT3 films were prepared for direct surface SEM scanning. Absorbed doses of 0-20 Gy were delivered to the film's surface using a 6 MV TrueBeam STx photon beam. The film's surface was scanned using a SEM under 100× and 3,000× magnification. Four textural features (Homogeneity, Correlation, Contrast, and Energy) were calculated based on the gray level co-occurrence matrix (GLCM) using the SEM images corresponding to each dose. We used R-square to evaluate the linear relationship between delivered doses and textural features of the film's surface. Results: Correlation resulted in higher linearity and dose-response curve sensitivity than Homogeneity, Contrast, or Energy. The R-square value was 0.964 for correlation using 3,000× magnified SEM images with 9-pixel offsets. Dose verification was used to determine the difference between the prescribed and measured doses for 0, 5, 10, 15, and 20 Gy as 0.09, 1.96, -2.29, 0.17, and 0.08 Gy, respectively. Conclusions: Texture analysis can be used to accurately convert microscopic structural changes to the EBT3 film's surface into absorbed doses. Our proposed method is feasible and may improve the accuracy of film dosimetry used to protect patients from excess radiation exposure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.316-321
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• 2000

In this study, heat collecting performance was study of flat plate solar collector by the angle. A method of study on were made turn out artificial sun by the angle of 0, 15, 30 degrees. The heat performances were measured the tube array surface temperature by thermo-couple. The winter season natural condition for 4 times on the angles of various general and emboss glass at optimum distance(0.68m) calculated of between sun and solar collector. To sum up temperature rise is appear more or less that emboss glass is all the better for general glass. The temperature variable at below of 30 degree was appear very less. The maximum performance of this system at that it is tilt angle of 30 with general glass is appear Q:11.54(kcal/min) and ${\Delta}T=18.9^{\circ}C$.

• 한국방사선학회논문지
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• 제16권5호
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• pp.519-526
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• 2022

능동형 전자식 개인피폭선량는 개인의 피폭 선량을 실시간으로 확인할 수 있는 장점을 가진 보조선량계이다. 하지만 국내에 사용되고 있는 다수의 능동형 개인피폭 선량계는 의료기관에서 사용하는 진단방사선 영역에서 큰 오차와 낮은 응답성을 가진다. 이에 본 연구에서는 Si 포토다이오드 검출기를 사용하는 능동형 전자식 개인선량계에서 저에너지 영역의 응답특성을 향상시키기 위한 에너지 보상 두께를 평가하였다. 40 kVp에서 80 kVp 영역에서는 Al 0.2 mm + Sn 1.0 mm 필터에서 우수한 응답특성을 보였고 80 kVp에서 120 kVp 영역에서는 Al 0.2 mm + Sn 1.6 mm 필터에서 우수한 응답특성을 보였다.

• 한국전자파학회논문지
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• 제10권1호
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• pp.109-121
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• 1999

본 논문에서는 HF 대의 대수주기 다이폴 안테나(LPDA: Log-Pericx:lic Dipole Antennas)와 변형된 대수 주기 다이폴 안테나(MLPDA: Mcx:lified Log-Periodic Dipole Antennas)를 대지의 매질 종류에 따라 자유공 간이나 완전도체에 놓인 것으로 큰사화하지 않고, 실제 대지의 매질을 고려하여 모멘트볍을 적용함으로써 복 사전계를 해석하였다 대지에 섣치된 LPDA와 MLPDA에 대하여 주파수. 안테나 높이, 경사각에 따른 복사 패턴과 이득의 변화를 나타내고 대지가 안테나 특성에 미치는 영향을 고찰하였다. 그 결과 MLPDA가 LPDA보다 주파수에 따른 복사패턴 및 이득의 변화가 적고 최대 빔 방향이 다소 높게 나타났으며, 또한 LPDA와 MLPDA 모두 대지의 매질 종류와 안테나의 높이가 안테나이득 변화에 주로 관계함을 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.76.1-76.1
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• 2015

Optical resonances of metallic or dielectric nanoantennas enable to effectively convert free-propagating electromagnetic waves to localized electromagnetic fields and vice versa. Plasmonic resonances of metal nanoantennas extremely modify the local density of optical states beyond the optical diffraction limit and thus facilitate highly-efficient light-emitting, nonlinear signal conversion, photovoltaics, and optical trapping. The leaky-mode resonances, or termed Mie resonances, allow dielectric nanoantennas to have a compact size even less than the wavelength scale. The dielectric nanoantennas exhibiting low optical losses and supporting both electric and magnetic resonances provide an alternative to their metallic counterparts. To extend the utility of metal and dielectric nanoantennas in further applications, e.g. metasurfaces and metamaterials, it is required to understand and engineer their scattering characteristics. At first, we characterize resonant plasmonic antenna radiations of a single-crystalline Ag nanowire over a wide spectral range from visible to near infrared regions. Dark-field optical microscope and direct far-field scanning measurements successfully identify the FP resonances and mode matching conditions of the antenna radiation, and reveal the mutual relation between the SPP dispersion and the far-field antenna radiation. Secondly, we perform a systematical study on resonant scattering properties of high-refractive-index dielectric nanoantennas. In this research, we examined Si nanoblock and electron-beam induced deposition (EBID) carbonaceous nanorod structures. Scattering spectra of the transverse-electric (TE) and transverse-magnetic (TM) leaky-mode resonances are measured by dark-field microscope spectroscopy. The leaky-mode resonances result a large scattering cross section approaching the theoretical single-channel scattering limit, and their wide tuning ranges enable vivid structural color generation over the full visible spectrum range from blue to green, yellow, and red. In particular, the lowest-order TM01 mode overcomes the diffraction limit. The finite-difference time-domain method and modal dispersion model successfully reproduce the experimental results.

• Radiation Oncology Journal
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• 제17권2호
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• pp.113-119
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• 1999

목적 :국소적으로 진행된 자궁경부암 환자에서 저용량의 Cisplatin을 방사선민감제로 사용하여 방사선치료와 동시 치료하였을 때의 급성독성 평가와 초기 반응을 평가하기 위하여 연구를 시행하였다. 대상 및 방법 : 본 연구는 1996년 12월부터 1999년 1월까지 FIGO Stage IIB-IIIB의 진행된 자궁경부암 환자 38명을 대상으로 하였다. 16명은 자궁경부암의 크기가 4cm이상인 환자들로 방사선 치료와 저용량의 cisplatin을 매일 동시에 치료 하였으며, 나머지 환자에선 방사선 치료 단독으로 치료하였다. 방사선치료는 골반강에 외부 방사선치료로 4500 cGy(3060cGy시행이후 midline block 추가), 자궁옅조직으로 침범이 있는 경우에는 자궁옅조직으로 방사선치료 부위를 줄여 900-1000cGy 추가치료를 시행하였고, 내부치료는 Ir$^{192}$고선량 근접 치료기(micro-Selectron HDR)로 6극회의 강 내조사(point "A"에 3000 to 3500cGy, 500cGy/fx, 2회/week)를 시행하였다. 방사선치료와 저용량의 cisplatin을 동시에 사용한 군에서는 방사선치료 첫날부터 방사선치료 20일째 되는 날까지 저용량의 cisplatin 10mg을 방사선치료 30분 전에 투여하였다. 급성독성의 평가는 expanded common toxicity criteria of the NCI Clinical Trial을 이용하였다. 초기반응의 평가는 방사선치료 종료이후 최소 4주이상의 추적조사가 가능한 사람들을 대상으로 시행되었다. 결과 : 급성독성 평가는 전체 38명에서 평가 가능하였으며, 방사선치료와 저용량의 cisplatin을 병용한 군에서 16명 중 6명(37.5$\%$)에서, 방사선 단독으로 치료한 군에서는 22명중 1명(6.2$\%$)에서 3등급 이상의 백혈구감소를 보였으며, 통계학적으로 의미있는 차이를 보였다 (P=0.030). 3등급 이상의 급성 위장간 독성은 저용량의 cisplatin을 병용한 군에서만 4명이 있었으나, 2-3일의 치료 중단이후 증상이 완화되어서 치료를 계속할 수 있었으며, 치료중 5kg이상의 체중감소는 방사선치료와 저용량의 cisplatin을 병용한 군에서는 16명중 3명(18.7$\%$), 방사선 단독으로 치료한 군에서는 22명중 2명(9.1$\%$)으로 통계학적으로 의미 있는 차이를 보이지 않았다(P=0.63). 초기반응은 추적조사가 4주 이상 가능하였던 34명을 대상으로 하였으며, 저용량의 cisplatin을 병용한 군에서 14명중 11명 (78$\%$), 방사선 단독으로 치료 군에서 20명중 16명(80$\%$)으로 통계학적으로는 의미있는 차이를 보이지 않았다(P=0.126). 결론 :국소 진행된 자궁경부암에 대한 방사선치료와 저용량의 cisplatin 병용요법 치료시 3등급 이상의 백혈구감소가 방사선치료 단독으로 치료시보다 많았으나, 1주 이하의 치료중단 이후 치료를 계속 할 수 있었으며, 4등급 이상의 백혈구감소와 치료에 의한 사망은 없었다. 초기반응에 대한 평가는 저용량의 cisplatin병용 군에서 4cm 이상의 자궁경부암을 가진 환자가 많음에도 불구하고 양 군에서 비슷한 정도의 반응을 보였으므로 진행된 자궁경부암의 치료에서 저용량의 cisplatin을 방사선민감제로 사용하여 치료결과의 향상을 기대할 수 있게 되었다. 따라서 저용량의 clsplatin과 방사선치료를 병용요법하였을 때의 치료효과를 판정하기 위해서는 phase III study가 필요하다.

• 대기
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• 제21권2호
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• pp.131-142
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• 2011

Spectral solar irradiances were observed using a visible and UV Multi-Filter Rotating Shadowband Radiometer on the rooftop of the Science Building at Yonsei University, Seoul ($37.57^{\circ}N$, $126.98^{\circ}E$, 86 m) during one year period in 2006. 1-min measurements of global(total) and diffuse solar irradiances over the solar zenith angle (SZA) ranges from $20^{\circ}$ to $70^{\circ}$ were used to examine the effects of clouds and total optical depth (TOD) on enhancing four solar irradiance components (broadband 395-955 nm, UV channel 304.5 nm, visible channel 495.2 nm, and infrared channel 869.2 nm) together with the sky camera images for the assessment of cloud conditions at the time of each measurement. The obtained clear-sky irradiance measurements were used for empirical model of clear-sky irradiance with the cosine of the solar zenith angle (SZA) as an independent variable. These developed models produce continuous estimates of global and diffuse solar irradiances for clear sky. Then, the clear-sky irradiances are used to estimate the effects of clouds and TOD on the enhancement of surface solar irradiance as a difference between the measured and the estimated clear-sky values. It was found that the enhancements occur at TODs less than 1.0 (i.e. transmissivity greater than 37%) when solar disk was not obscured or obscured by optically thin clouds. Although the TOD is less than 1.0, the probability of the occurrence for the enhancements shows 50~65% depending on four different solar radiation components with the low UV irradiance. The cumulus types such as stratoculmus and altoculumus were found to produce localized enhancement of broadband global solar irradiance of up to 36.0% at TOD of 0.43 under overcast skies (cloud cover 90%) when direct solar beam was unobstructed through the broken clouds. However, those same type clouds were found to attenuate up to 80% of the incoming global solar irradiance at TOD of about 7.0. The maximum global UV enhancement was only 3.8% which is much lower than those of other three solar components because of the light scattering efficiency of cloud drops. It was shown that the most of the enhancements occurred under cloud cover from 40 to 90%. The broadband global enhancement greater than 20% occurred for SZAs ranging from 28 to $62^{\circ}$. The broadband diffuse irradiance has been increased up to 467.8% (TOD 0.34) by clouds. In the case of channel 869.0 nm, the maximum diffuse enhancement was 609.5%. Thus, it is required to measure irradiance for various cloud conditions in order to obtain climatological values, to trace the differences among cloud types, and to eventually estimate the influence on solar irradiance by cloud characteristics.