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Acquisition of High Resolution Images and its Application using Synchrotron Radiation Imaging System (방사광 X-선을 이용한 고해상도 영상획득과 응용)

  • 홍순일;김희중;정해조;홍진오;정하규;김동욱;제정호;김보라;유형식
    • Progress in Medical Physics
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    • v.12 no.1
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    • pp.51-58
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    • 2001
  • Synchrotron radiation (SR) has several advantages over convetional x-rays, including its phase, collimation, and high flux. A synchrotron radiation beamline 5C1 at Pohang Light Source (PLS) was recently built for imaging applications. We have shown that a SR imaging system is useful in imaging microscopic structures. SR with broad-band energy spectrum were adjusted to an object by Si wafers and their energy were approximately ranging from 6 keV to 30 keV. SR were passed through an object and finally transformed into visible lights by CdWO$_4$ scintillator screen. The visible lights which were reflected at an angle of 90 degrees by gold plated mirror were detected by a CCD camera and the image data were acquired using image acquisition system. A high-resolution phantom, capacitor, adult tooth, child tooth, cancerous breast tissue, and mouse lumbar vertebra were imaged with SR imaging system. The Objects were rotated within the field of view of the CCD detector, and their projection image data were obtained at 250 steps over 180 degrees rotation. Image reconstructions were carried out in a PC by using IDLTM(Research systems, Inc., US) program. The spatial resolution of the images acquired by the SR imaging system was measured with a high-resolution chart manufactured for several micrometer resolution. The specimens were also imaged with conventional x-ray radiography system to compare the image quality of radiography obtained with the SR imaging system. The results showed more structural details and high contrast images with SR imaging system than conventional x-ray radiography system. The SR imaging system may have a potential for imaging in biological researches, material applications, and clinical radiography.

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An Empirical Study on the Lead/Lag Effects in the KOSPI 200 Cash, futures, and Option Markets (우리나라 주식, 선물, 옵션시장에서의 선도/지연효과에 관한 연구)

  • Kim, Chan-Wung;Moon, Gyu-Hyun
    • The Korean Journal of Financial Management
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    • v.18 no.1
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    • pp.129-156
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    • 2001
  • 본 연구는 1997년 11월 1일부터 1998년 9월 20일까지의 5분 단위로 측정된 거래 자료를 이용하여, KOSPI 200 선물시장, KOSPI 200 옵션시장 및 KOSPI 200 주가지수간의 선도/지연관계를 실증 분석하였다. 분석방법은 다양한 시계열 분석방법들을 이용하였으며 주요 결과는 다음과 같다. 첫째, 선물시장은 현물시장을 25분간 선도하였으며, 현물시장도 선물시장을 10분 정도 선도하였다. 둘째, 옵션시장도 현물시장을 약 20분간 선도하며, 약하지만 현물시장도 옵션시장을 5분에서 10분 가량 선도하였다. 셋째, 선물시장은 옵션시장을 20여분간 강하게 선도하였고, 옵션시장도 선물시장을 5분 정도 선도하였다. 넷째, 거래량이 적고 변동성이 높은 경우 선도/지연관계의 차이가 존재하는 것으로 나타났다. 다섯째, 옵션의 외가격과 등가격에 따른 시장간의 선도/지연관계의 분석결과 주가지수, 선물, 옵션의 선도/지연관계는 등가격과 외가격옵션에서 거의 비슷하게 나타났지만 등가격에서 현물에 대한 선물과 옵션시장의 선도효과가 강하게 나타났다.

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Eu을 도핑한 ZnS 나노선의 온도변화에 따른 광발광 감쇄

  • Sin, Yong-Ho;Kim, Yong-Min;Kim, Sang-Dan;Ju, Sang-Hyeon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.416-416
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    • 2012
  • Eu이 도핑된 ZnS 나노선을 제작하여 온도변화에 따른 광발광 변화를 측정하였다. ESR 측정을 통하여 제작된 시료의 도펀트가 Eu2+ 상태임을 확인하였다. Au-catalyst와 Eu 도펀트 관련전이(Fig. 1, P2)와 표면 상태와 관련된 exciton (P1)의 온도변화에 대한 발광특성들이 100 meV 내외의 매우 큰 활성화 에너지를 가짐을 알 수 있었다. 이들 나노선들이 상온에서도 매우 강하게 발광하는 특성이 첨가된 도펀트와 강하게 관련이 있음을 알 수 있었으며, 이 실험을 통하여 Eu을 도핑한 ZnS 나노선들이 발광 소자로 이용 가능성함을 확인하였다.

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Evaluation of the home power line channel's communication reliability in Internet operation of home appliances (전력선 통신망 네트워크상의 가전제품 통신 신뢰도 측정 및 분석에 관한 연구)

  • Ahn Nam-Ho;Choi Won-Sup;Chang Tae-Gyu;Kim Hoon
    • Journal of The Institute of Information and Telecommunication Facilities Engineering
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    • v.1 no.1
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    • pp.65-72
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    • 2002
  • 본 논문에서는 인터넷 가전제어를 위한 전력선 통신망 채널 특성 추정 기법을 제시하였고 실 거주 댁내 전력선 통신망의 채널 특성을 실측하여 통신 신뢰도를 평가하였다. 전력선 통신 기능을 내장한 동일 모델의 네트워크 가전제품 4종(에어컨, 냉장고, 세탁기, 전자렌지)을 실 거주 가정 100가구에 설치하여 전력선 통신망의 통신 신뢰도를 평가하였다. 통신 신뢰도의 평가 결과 통신 신뢰도가 90%이상이 나타나는 것을 확인하였다. 이것은 PLC모뎀이 장착된 가전제품의 활용과 고밀도 아파트 주거 지역에서 인터넷 가전제어를 위한 서비스가 상업적으로 이용할 수 있는 근거를 뒷받침한다고 할 수 있다.

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A Study on the Measuring the Grounding Resistance Using the Leakage Current in the Ground Conductor (접지선 누설전류를 이용한 접지저항 측정에 관한 연구)

  • Kang Moon Ho
    • Proceedings of the KIEE Conference
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    • summer
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    • pp.515-517
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    • 2004
  • 현재 배전선로는 4가지 접지종별을 준용하여 피뢰기, 가공지선, 변압기, 기기류, 중성선 둥을 접지시공하고 있다. 또한 규정된 접지저항값에 따라 접지전극을 시공하고 2년에 1회 주기적으로 접지저항값을 측정하고 관리하고 있다. 현재 접지저항값의 측정에는 휴대가 간편하고 측정이 용이한 HOOK-ON 접지저항계가 주로 이용되고 있다. 그러나 HOOK-ON 접지저항계는 $\pm$5[\%]$정도의 측정오차 뿐만 아니라 측정선 전류가 1[A]를 초과하는 경우 변류용 철심이 포화되어 측정이 어렵다는 단점을 가지고 있다. 따라서 본 논문에서는 HOOK-ON 측정기법의 단점을 보완하여 다중접지 배전계통에서 부하 불평형 및 고조파 둥에 의해 발생하는 접지선 누설전류를 전류원으로 이용하는 접지전극의 접지저항을 측정하는 새로운 측정기법을 제안하였다. 또한 이를 실제 배전계통에 적용하여 전위강하법을 이용하여 측정한 접지저항값과 비교하였다.

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Synthesis and Characterization of $In_2O_3$ Nanowires in a Wet Oxidizing Environment (습식 산화 분위기에서의 산화 인듐 나노선의 합성 및 구조적 특성)

  • Jeong, Jong-Seok;Kim, Young-Heon;Lee, Jeong-Yong
    • Applied Microscopy
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    • v.33 no.1
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    • pp.17-23
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    • 2003
  • Indium oxide ($In_2O_3$) nanowires were successfully synthesized by a simple reaction in a wet oxidizing environment at low temperature without metal catalyst. The nanowires were characterized by an x-ray diffraction (XRD), a scanning electron microscopy (SEM) equipped with an energy dispersive spectrometry (EDS), and a transmission electron microscopy (TEM). It was shown that the $In_2O_3$ nanowires were two types of morphology, uniform nanowires and nanowires containing $In_2O_3$ nanoparticles in its stem. It was found that lengths of the nanowires were ranges of several micrometers and their diameters were around $10{\sim}250$ nm. The growth direction of the nanowires was investigated and their growth mechanism is also discussed.

Effects of Specific Gravity on Germination and Emergence of Foxtail Millet (Setaria italica Beauvois) (염수선 종자 정선법에 따른 조의 발아 및 출현율)

  • Jung, Ki-Youl;Choi, Young-Dae;Chun, Hyen-Chung;Lee, Sang-Hun;Jeon, Seung-Ho
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.64 no.2
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    • pp.144-151
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    • 2019
  • The establishment rate of foxtail millet seeds is greatly affected by soil environment conditions. To enhance germination viability and stable production of foxtail millet seeds, it is important to select seeds with a high density. Therefore, this study tested the selection of high-quality seeds using salt solution (specific gravity: 1.000, 1.005, 1.010, 1.015, 1.020, 1.025, 1.030, 1.035, and $1.040g\;L^{-1}$) and investigated their germination rates, percentages of emergence, and seeding quality. In this study, three varieties were tested: 'Hwanggeum', 'Samdachal', and 'Kyeongkwan1'. The thousand seed weight of all three varieties increased proportionally with specific gravity. The highest thousand seed weight was observed at the selection with $1.040g\;L^{-1}$ specific gravity, which also had the highest germination rate of 88.3%, 86.7%, and 90.6%, for 'Hwanggeum'; 'Samdachal'; and 'Kyeongkwan1', respectively. The results of seeding quality indicated that higher the specific gravity during selection, the higher were the values of plant growth (plant height, leaf length, stem diameter, root length, root weight, and stem weight). All the three varieties were found to be longer or heavier for seeds selected at the specific gravity of $1.040g\;L^{-1}$. The packing germination viability investigation found that higher the specific gravity for selection of seeds, the higher was the percentage of emergence (PE) and the emergence rate index (ERI). The PE was the highest for seeds selected at $1.040g\;L^{-1}$ specific gravity (85.3, 83.0, and 87.0%), and ERI was also as high as $2.82d^{-1}\;m^{-1}$ or more at $1.040g\;L^{-1}$. Selection of seeds with salt solution resulted in high germination viability of foxtail millet. Therefore, sowing seeds selected at $1.040g\;L^{-1}$ specific gravity is expected to help substantially in increased productivity.

Feasibility Study of the Radiophotoluminescent Glass Dosimeter for High-energy Electron Beams (유리선량계를 이용한 고에너지 전자선 측정 이용 가능성에 관한 연구)

  • Son, Ki-Hong;Jung, Hai-Jo;Shin, Sang-Hun;Lee, Hyun-Ho;Lee, Sung-Hyun;Kim, Mi-Sook;Ji, Young-Hoon;Kim, Kum-Bae
    • Progress in Medical Physics
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    • v.22 no.1
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    • pp.52-58
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    • 2011
  • Our goal is to assess the suitability of a glass dosimeter on detection of high-energy electron beams for clinical use, especially for radiation therapy. We examined the dosimetric characteristics of glass dosimeters including dose linearity, reproducibility, angular dependence, dose rate dependence, and energy dependence of 5 different electron energy qualities. The GD was irradiated with high-energy electron beams from the medical linear accelerator andgamma rays from a cobalt-60 teletherapy unit. All irradiations were performed in a water phantom. The result of the dose linearity for high-energy electron beams showed well fitted regression line with the coefficient of determination; $R^2$ of 0.999 between 6 and 20 MeV. The reproducibility of GDs exposed to the nominal electron energies 6, 9, 12, 16, and 20 MeV was ${\pm}1.2%$. In terms of the angular dependence to electron beams,GD response differences to the electron beam were within 1.5% for angles ranging from $0^{\circ}$ to $90^{\circ}$ and GD's maximum response differencewas 14% lower at 180o. In the dose rate dependence, measured dose values were normalized to the value obtained from 500 MU/min. The uncertainties of dose rate were measured within ${\pm}1.5%$ except for the value from 100 MU/min. In the evaluation of the energy dependence of the GD at nominal electron energies between 6 and 20 MeV, we obtained lower responses between 1.1% and 4.5% based on cobalt-60 beam. Our results show that GDs have a considerable potentiality for measuring doses delivered by high-energy electron beams.