• 열병합발전
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• s.22
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• pp.34-37
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• 2001

• NEWSLETTER 전기공업
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• no.99-11 s.228
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• pp.9-37
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• 1999

• Journal of radiological science and technology
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• v.39 no.1
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• pp.99-105
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• 2016

The noise power spectrum (NPS) is one of the most general methods for measuring the noise amplitude and the quality of an image acquired from a uniform radiation field. The purpose of this study was to compare different NPS methodologies by using megavoltage X-ray energies. The NPS evaluation methods in diagnostic radiation were applied to therapy using the International Electro-technical Commission standard (IEC 62220-1). Various radiation therapy (RT) devices such as TrueBeam$^{TM}$(Varian), BEAMVIEW$^{PLUS}$(Siemens), iViewGT(Elekta) and Clinac$^R$ iX (Varian) were used. In order to measure the region of interest (ROI) of the NPS, we used the following four factors: the overlapping impact, the non-overlapping impact, the flatness and penumbra. As for NPS results, iViewGT(Elekta) had the higher amplitude of noise, compared to BEAMVIEW$^{PLUS}$ (Siemens), TrueBeam$^{TM}$(Varian) flattening filter, Clinac$^{R}$iXaS1000(Varian) and TrueBeam$^{TM}$(Varian) flattening filter free. The present study revealed that various factors could be employed to produce megavoltage imaging (MVI) of the NPS and as a baseline standard for NPS methodologies control in MVI.

• The korean journal of orthodontics
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• v.17 no.2
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• pp.255-277
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• 1987

부정교합(不正交合)의 발생요인(發生要因)의 하나로서 비인두강(鼻咽頭腔)의 협착(狹窄)이 거론(擧論)되어 왔다 본(本) 연구(硏究)는 안면골격(顔面骨格)의 형태결정(形態決定)에 비인두강(鼻咽頭腔)의 기여정도(寄與程度)를 파악(把握)하고자 함에 있다 연구자료(硏究資料) 및 방법안(方法安) 한국인(韓國人) 성인(成人) 남녀(男女) 156 명(名)의 측모두부X선규격사진(側貌頭部X線規格寫眞)을 사용(使用)하여 NEC PC-9801 VM2 Personal Computer와 Oscon GT-4000 Digitizer에 의한 data 입력(入力)을 행(行)한 후 통계처리(統計處理)를 행(行)하였다 통계처리(統計處理)로서는 각계측치(各計測値)에 대하여 남녀별(男女別)로 평균치(平均値), 표준편차치(標準偏差値)를 산출(算出), Student's t-test를 행(行)하고, 비인두강(鼻咽頭腔) 계측항목(計測項目)과 안면골격(顔面骨格)의 각(各) 계측치간(計測値間)의 상관관계(相關關係)의 검토(檢討)를 행(行)하였다 결(結) 과(果) 1 남녀(男女)의 성차(性差)로서, 여자(女子)보다 남자(男子)가 상악골(上顎骨)에 대해 하악골(下顎骨)이 돌출(突出)되어 있었으며, 안면고(顔面高)가 컸다 2 Ba-S-PNS와 S-PNS-Ba간(間)에 부(負)의 상관(相關)이 인정(認定)되어, 이 두 계측치간(計測値間)애 상호작용(相互作用)이 있는 것으로 판단 되었다 3 비인두강(鼻咽頭腔)의 깊이는 하악(下顎)의 전후위치관계(前後位置關係)와 유의(留意)한 상관관계(相關關係)를 보였다 4 비인두강(鼻咽頭腔)의 깊이와 안면(顔面)의 깊이와는 관련성(關聯性)이 없는 것으로 판단 되었다 5 비인두강(鼻咽頭腔)의 깊이와 안면고간(顔面高間)에 유의(有意)한 부(負)의 상관(相關)이 시사(示唆)되었다 6 비인두강(鼻咽頭腔)의 고경(高經)과 안면고간(顔面高間)에 유의(有意)한 상관관계(相關關係)가 인정(認定)되었다.

• Journal of radiological science and technology
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• v.39 no.2
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• pp.171-176
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• 2016

The quality assurance (QA) is very important for diagnostic field and radiation therapy field to evaluate the characteristic of devices. The purpose of this study was to compare different NPS methodologies results which are measuring NPS with regard to horizontal and vertical directions by using megavoltage X-ray energies. The NPS evaluation methods were applied to the International Electro-technical Commission standard (IEC 62220-1). The electronic portal imaging devices (EPID) devices such as Siemens BEAMVIEW$^{PLUS}$, Elekta iViewGT and Varian Clinac$^R$ iX aS1000 were used. NPS data were expressed by corresponding each frequency about average of noise value corresponding the each frequency, and NPS were evaluated quantitatively by totaling up the noise values of average frequency which are on horizontal and vertical directions. In NPS results for Elekta iViewGT, NPS of horizontal and vertical by using 4 methods were indicated the difference of 3~5% between horizontal and vertical direction. In the results of Siemens BEAMVIEW$^{PLUS}$ and Varian Clinac$^R$ iX aS1000, the NPS of horizontal and vertical direction were indicated the difference of 15% when averaging the whole values. This study were evaluated the NPS of each devices by totaling up the noise values of average frequency which are on horizontal and vertical directions suggesting the quantitative evaluation method using the data.