• Journal of Plant Biology
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• 제5권1호
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• pp.1-6
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• 1962

1) Germination rate was rather irregular than decreasing as increasing dose of radiation and there were no differences between Kyong-Sam and Chuong-Bang of Chinese cabbage. 2) In R1 generation, abnormal leaves from seedling of irradiated seeds were observed. These were more apparent in X-ray irradiation than in thermal neutron. 3) Seedling height was inhibited with increasing dose of X-ray and thermal neutrons. Growth inhibition was more remarkable in X-ray than in thermal neutron. Kyong-Sam demonstrated more sensitivity than Chyong-Bang in both X-ray and thermal neutron. 4) Seedling height produced from seeds subjected to thermal neutrons showed small variation around its mean value, while in X-irradiation there was a greater deviaton from the mean value. 5) Fertility was decreased as increasing with dose, while the frequency of abortive pollen was increased. There were variability of the fertility and frequency of abortive pollen among plants or branches of a plant. 6) The mutants were obtained more in thermal neutron irradiation than in X-ray. The types of mutations obtained in Chinese radish of R2 generation were abnormal leaf, densely glowing leaf, degeneration in growing point and dwarf. The maximum frequency of phenotypic mutations was abnormal leaf mutation.

• 한국광학회:학술대회논문집
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• 한국광학회 1995년도 광학 및 양자전자학 워크샵 논문집
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• pp.185-189
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• 1995

A high-power Nb:glass laser system(Simmyung I) has been contructed and tested. In this system, we used a Nb:YLF laser as a master oscillator, a 4-pass amplifier for pre-amplification, 5 stages of rod amplifiers, and spatial filtering and image reaying usits. The system has demonstrated in excess of 80J(2TW) with 40 psec(FWHM) pulse duration. Output energy, gain and spatial were measured at each amplification stage. With this laser system a preliminary X-ray generation experiment was performed. Pinhole images, X-ray diode signals and X-ray speriment were obtained for the irradiated target of copper. Detailed descriptions of the system performance and the X-tay generation experiment are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2095-2097
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• 2000

Applications of soft X-ray which corresponds to the wavelength of the order of 1 nm and to the photon energy of the order of 1 key respectively, requires intense sources. Only synchrotron sources were available recently. The development of a new laboratory-sized source of soft X-ray radiation is required for wide applications. This paper introduces the generation of soft X-ray using laser-induced plasma.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.80-85
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• 2009

An experimental study of energy absorption and x-ray emission from ultrashort laser pulse irradiation of in-situ produced solid clusters has been performed. Silver clusters produced by a 30 mJ, 300 ps laser pulse were irradiated up to an intensity of $3{\times}10^{17}\;W/cm^2$ by a 70 mJ, 45 fs compressed laser pulse from the same Ti:sapphire laser. Absorption of the laser light exceeding 70% was observed, resulting in an x-ray yield (>1 keV) of ${\sim}60{\mu}J$ pulse. This may constitute a much simpler means of intense x-ray generation using ultrashort laser pulses as compared to the irradiation of structured / pre-deposited cluster targets, and it offers higher x-ray conversion efficiency than that from gas clusters and planar solid targets.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.795-798
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• 2016

Transmission X-ray tubes based on carbon nanotube have attracted significant attention recently. In most of these tubes, tungsten is used as the target material. In this article, the well-known simulator Geant4 was used to obtain some of the tungsten target parameters. The optimal thickness for maximum production of usable X-rays when the target is exposed to electron beams of different energies was obtained. The linear variation of optimal thickness of the target for different electron energies was also obtained. The data obtained in this study can be used to design X-ray tubes. A beryllium window was considered for the X-ray tube. The X-ray energy spectra at the moment of production and after passing through the target and window for different electron energies in the 30-110 keV range were also obtained. The results obtained show that with a specific thickness, the target material itself can act as filter, which enables generation of X-rays with a limited energy.

• 한국CDE학회논문집
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• 제16권4호
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• pp.285-291
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• 2011

A pose estimation process from medical images is calculating locations and orientations of objects obtained from Computed Tomography (CT) volume data utilizing X-ray images from two directions. In this process, digitally reconstructed radiograph (DRR) images of spatially transformed objects are generated and compared to X-ray images repeatedly until reasonable transformation matrices of the objects are found. The DRR generation and image comparison take majority of the total time for this pose estimation. In this paper, a fast DRR generation technique based on GPU parallel computing is introduced. A volume ray-casting algorithm is explained with brief vector operations and a parallelization technique of the algorithm using Compute Unified Device Architecture (CUDA) is discussed. This paper also presents the implementation results and time measurements comparing to those from pure-CPU implementation and open source toolkit.

• 진공이야기
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• 제3권4호
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• pp.4-7
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• 2016

An X-ray Free Electron laser facility (PAL-XFEL) has been built in Pohang Accelerator Laboratory to provide X-ray FEL radiations for photon users. The machine consists of a 10 GeV normalconducting S-band linear accelerator and two undulator beamlines. The hard and soft X-ray beamlines will provide FEL radiations with wavelengths of 0.6 to 0.1 nm and 4.5 to 1 nm, respectively. Beam commissioning of PAL-XFEL is ongoing and user service will start in 2017. In this report, the PAL-XFEL layout and the working principle are discussed.

• Bulletin of the Korean Chemical Society
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• 제25권11호
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• pp.1676-1680
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• 2004

We demonstrate that wide-angle X-ray scattering pattern from photoactive yellow protein (PYP) in solution using a high flux third generation synchrotron X-ray source reflects not only the overall structure, but also fine structures of the protein. X-ray scattering data from PYP in solution have been collected in q ranges from 0.02 ${\AA}^{-1}$ to 2.8 ${\AA}^{-1}$. These data are sensitive to the protein structure and consistent with the calculation based on known crystallographic atomic coordinates. Theoretical scattering patterns were also calculated for the intermediates during the photocycle of PYP to estimate the feasibility of time-resolved wide-angle X-ray scattering experiments on such proteins. These results demonstrate the possibility of using the wide-angle solution X-ray scattering as a quantitative monitor of photo-induced structural changes in PYP.

• 한국전기전자재료학회논문지
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• 제24권8호
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• pp.647-653
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• 2011

In this study, a method to measure the thickness of thin film by EDS (energy dispersive spectroscopy) is suggested. We have developed a model which calculates the thickness of thin film from the characteristic x-ray intensity ratio of the elements in thin film and substrate by considering incident electron beam energy, x-ray generation curve, backscattering and absorption of x-ray, take-off angle of x-ray and tilt angle of the sample. We obtained the relation curve between the film thickness measured experimentally and the x-ray intensity ratio of elements. The film thicknesses calculated from the model agrees quite well with those measured experimentally. Therefore, the thin film thickness can be measured rapidly and accurately by using the model developed in this study and the x-ray intensity ratio obtained in EDS analysis.

• 한국응용곤충학회지
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• 제53권4호
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• pp.391-398
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• 2014

4종 해충(복숭아혹진딧물, 점박이응애, 아메리카잎굴파리, 대만총채벌레)에 이온화에너지인 전자빔과 X-ray를 각각 조사하여 이들 해충의 발육과 생식에 미치는 영향을 비교하여 억제선량을 결정하였다. 복숭아혹진딧물 약충에 전자빔과 X-ray 조사 시, 전자빔의 경우에는 100 Gy, X-ray의 경우에는 30 Gy에서 우화성충의 산자가 완전히 억제되었다. 복숭아혹진딧물 성충의 경우 200 Gy (전자빔)와 50 Gy (X-ray)에서 각각 $F_1$ 세대 약충의 우화가 억제되었다. 그러나 이들 두 이온화에너지 모두 성충수명에는 영향을 주지 않았다. 점박이응애의 알에서는 전자빔 150 Gy와 X-ray 50 Gy 선량에서 알의 부화가 완전히 억제되었다. 아메리카잎굴파리 번데기에서는 X-ray 조사선량이 증가할수록 우화율이 감소하였다. 대만총채벌레 성충에 조사 시 전자빔의 250 Gy와 X-ray의 200 Gy 선량에서 $F_1$ 세대 알의 부화가 완전히 억제되었다.