마이크로스트립 구조 해석을 위한 Closed-Form 그린 함수

양승우(Seung-Woo Yang),김성진(Sung-Jin Kim),김건우(Gun-Woo Kim),이택경(Taek-Kyung Lee) 한국전자파학회 2008 한국전자파학회논문지 Vol.19 No.3

평면형 구조에서 공간 영역 그린 함수를 구하기 위해서는 무한 Sommerfeld 적분을 계산하여야 한다. 무한적분을 짧은 시간에 계산하기 위한 실수축 적분 방법(real axis integration method)은 주파수와 거리에 대해 넓은 범위에 걸쳐 매우 정확한 방법이지만 관측점의 수직 성분 z가 변하게 되면, 근사의 과정을 반복해야 하는 비효율성과 z가 커질수록 파수 영역 함수의 변화가 심해져 정확한 근사가 어렵다는 단점이 있다. 본 논문에서는 폐루프 적분 경로를 이용하여 파수 영역 함수를 근사화 함으로써 일반적인 마이크로스트립 구조에서 기존의 결과에 비해 정확한 closed-form 그린 함수를 구하는 방법을 제시하였다. In the layered medium, the Sommerfeld integral must be evaluated to calculate a space domain Green's function. The real axis integration method provides stable and accurate results over wide ranges of the observation distance and the singnal frequency. But this method has the inefficiency of approximation when the field point z is changed. Also, as the amplitude of z increases, the change of the spectral domain function is more rapidly. Therefore, the approximation is difficult when z becomes larger. In this paper, we propose a method to calculate an accurate closed-form Green's function for microstrip structure by using the closed-loop integration path.

혁신정책의 변인(變因) 수용과 과학기술 법제 간 정합성 제고방안

양승우(Seung-Woo Yang),홍성주(Sung-Joo Hong),신은정(Eun-Jung Shin),우청원(Chung-Won Woo),김영린(Yeong-Lin Kim),최지선(Ji-Sun Choi) 과학기술정책연구원 2017 정책연구 Vol.- No.-

피부선량 측정을 위한 Lead-Monoxide 기반의 Silicon Passive layer PbO 선량계 개발 및 평가

양승우(Seung-Woo Yang),한무재(Moo-Jae Han),정재훈(Jae-Hoon Jung),배상일(Sang-Il Bae),문영민(Young-Min Moon),박성광(Sung-Kwang Park),김진영(Jin-Young Kim) 한국방사선학회 2021 한국방사선학회 논문지 Vol.15 No.6

피부는 방사선에 대한 민감도가 높기 때문에 방사선치료 시에 피부에 조사되는 선량을 정확하게 측정하여 과도한 피폭을 방지할 필요가 있다. 임상에서는 film, OSLD, TLD, glass 선량계등과 같은 선량계를 사용하여 피부선량을 측정하고 있지만, 이러한 선량계들은 피부곡면에서의 정확한 선량측정이 힘든 문제점이 있다. 본 논문에서는 이러한 문제를 해결하고자 인체 굴곡에 따라서 부착이 가능한 피부선량계를 개발하고 그 반응 특성을 평가하였다. 선량계 제작에는 높은 원자번호(ZPb: 82, ZO: 8)와 밀도(9.53 g/cm3)로 방사선검출 측점에서 우수한 특성을 가지고 있는 Lead oxide(PbO)와 인체 굴곡에 따라 휘어질 수 있는 silicon 바인더를 사용하여 재조하였다. 한편 PbO 물질로 제작된 선량계의 경우 산화로 인한 성능 저하가 존재하기 때문에 parylene 등을 사용하여 성능저하를 방지해오고 있었지만, 기존에 사용된 parylene은 bending에 대한 영향을 받기 때문에 silicon을 이용한 새로운 형태의 passive layer를 제작하여 피부선량계에 적용하였다. 피부선량계의 특성평가는 SEM, 재현성, 선형성을 분석하여 평가하였다. SEM 분석을 통하여 bending에 영향을 받는지 평가하였으며, 6 MeV 에너지에서의 재현성, 선형성을 평가하여 피부선량계로 적용이 가능한지 평가하였다. SEM 분석을 통하여 선량계 표면을 관찰한 결과, parylene으로 passive layer가 올라간 parylene passive layer PbO 선량계는 구부러 졌을때, 표면에 crack이 발생하였다. 그에 반해 silicon passive layer가 올라간 silicon passive layer PbO 선량계에서는 crack 이 관찰되지 않았다. 재현성 측정 결과에서 silicon passive layer PbO 선량계의 RSD는 1.47%로 평가기준 RSD 1.5%를 만족하였으며, 선형성 평가 결과에서는 R2값이 0.9998로 나타나 평가기준 R2 0.9990을 만족하였다. silicon passive layer PbO 선량계는 bending에 따른 crack이 발생하지 않으며, 재현성, 선형성에서 높은 신호안정성과 정밀성, 정확성을 보여주어 피부선량계로의 적용이 가능한 것으로 평가되었다. Due to the high sensitivity to radiation, excessive exposure needs to be prevented by accurately measuring the dose irradiated to the skin during radiation therapy. Although clinical trials use dosimeters such as film, OSLD, TLD, glass dosimeter, etc. to measure skin dose, these dosimeters have difficulty in accurate dosimetry on skin curves. In this study, to solve these problems, we developed a skin dosimeter that can be attached according to human flexion and evaluated its response characteristics. For the manufacture of the dosimeter, lead oxide (PbO) with high atomic number (ZPb: 82, ZO: 8) and density (9.53 g/cm3) and silicon binders that can bend according to human flexion were used. In the case of a dosimeter made of PbO material, the performance degradation has been prevented by using parylene and others due to the presence of degradation due to oxidation, but the previously used parylene is affected by bending, so a new form of passive layer was produced and applied to the skin dosimeter. The characteristic evaluation of the skin dosimeter was evaluated by analyzing SEM, reproducibility, and linearity. Through SEM analysis, bending was evaluated, reproducibility and linearity at 6 MeV energy were evaluated, and applicability was assessed with a skin dosimeter. As a result of observing the dosimeter surface through SEM analysis, the parylene passive layer PbO dosimeter with the positive layer raised to the parylene produced cracks on the surface when bent. On the other hand, no crack was observed in the silicon passive layer PbO dosimeter, which was raised to silicon passive layer. In the reproducibility measurement results, the RSD of the silicon passive layer PbO dosimeter was 1.47% which satisfied the evaluation criteria RSD 1.5% and the linearity evaluation results showed the R2 value of 0.9990, which satisfied the evaluation criteria R2 9990. The silicon passive layer PbO dosimeter was evaluated to be applicable to skin dosimeters by demonstrating high signal stability, precision, and accuracy in reproducibility and linearity, without cracking due to bending.

일제시대 서울 도심부 회사 입지 및 가로망 변화의 특성에 관한 연구

양승우(Yang, Seung-Woo),최상근(Choi, Sang-Keun) 한국도시설계학회 2001 도시설계 : 한국도시설계학회지 Vol.5 No.1

개발제한구역 취락지구 지정방법 개발 및 적용에 관한 연구

양승우(Seung-Woo Yang),이상경(Sang-Kyeong Lee),정창무(Chang-Mu Jung),배정남(Jeong-Nam Bae) 서울연구원 2006 서울도시연구 Vol.7 No.3

방사선근접치료 분야의 선량 측정을 위해 제조된 Lead(Ⅱ) Iodide 선량계의 적용가능성 연구

양승우(Seung-Woo Yang),한무재(Moo-Jae Han),박성광(Sung-Kwang Park) 한국방사선학회 2021 한국방사선학회 논문지 Vol.15 No.6

근접방사선치료는 방사선동위원소를 신체 내부에 넣어 종양에 방사선을 집중적으로 조사하는 치료법이다. 근접방사선 치료는 고선량율의 방사선동위원소 선원을 사용하기 때문에 정확한 선원의 위치 및 선량등을 파악하는 것이 매우 중요하다. 하지만 임상에서는 ruler, autoradiograph등을 통하여 육안으로 부정확하게 평가하는 실정이다. 이에 본 연구에서는 Lead(Ⅱ) Iodide(PbI2) 물질을 사용하여 방사선근접치료에 사용할 수 있는 선량계를 개발하고, 재현성, 선형성, PID 항목을 분석하여 적용가능성을 평가하였다. 재현성 평가결과, RSD 값은 1.41%로 평가기준 1.5%를 만족하였다. 선형성 평가결과, R2값은 0.9993으로 평가기준 0.9990을 만족하였다. PID 평가 결과 50% 선량 감약지점에서 거리의 역자승 법칙의 이론값과 비교하여 0.06 cm의 차이만을 나타내었다. 본 실험에서 제작된 선량계는 모든 평가에서 기준치를 만족하는 결과값을 나타내어 방사선근접치료 영역에서의 선량계 적용 가능성이 충분한 것으로 판단된다. Brachytherapy is a treatment in which radioactive isotopes are placed inside the body to intensively irradiate the tumor with radiation. Because brachytherapy uses a radioisotope source with a high dose rate, it is very important to know the exact location and dose of the source. However, in clinical practice, it is evaluated inaccurately with the naked eye through rulers and autoradiographs. Therefore, in this study, a dosimeter that can be used for brachytherapy was developed using a lead(II) iodide (PbI2) material, and the applicability was evaluated by analyzing the reproducibility, linearity, and PID items. As a result of reproducibility evaluation, the RSD value was 1.41%, satisfying the evaluation criteria of 1.5%. As a result of the linearity evaluation, the R2 value was 0.9993, which satisfies the evaluation criterion of 0.9990. As a result of PID evaluation, it showed only a difference of 0.06 cm compared with the theoretical value of the inverse square law of distance at the 50% dose reduction point. The dosimeter manufactured in this experiment shows results that satisfy the standard in all evaluations, so it is judged that the possibility of applying the dosimeter in the radiation brachytherapy area is sufficient.

Reliability Verification of FLUKA Transport Code for Double Layered X-ray Protective Sheet Design

Sang Sik Kang(강상식),Seung Wook Heo(허승욱),Il Hong Choi(최일홍),Jae Hoon Jun(전제훈),Sung Woo Yang(양승우),Kyo Tae Kim(김교태),Ye Ji Heo(허예지),Ji Koon Park(박지군) 한국방사선학회 2017 한국방사선학회 논문지 Vol.11 No.7

현재 의료분야에서는 방사선 차폐체로서 납(Pb)이 널리 쓰이고 있다. 하지만 납은 무게가 매우 무거워 납 치마 등의 방호복은 장시간 착용이 어려우며, 인체에 치명적인 납 중독의 위험이 상시 가지고 있다는 문제점을 가지고 있다. 이러한 문제점을 해결하고자 납을 대체 할 수 있는 물질에 대한 많은 연구가 진행되고 있다. 현재 납의 대체물질로써 대표적인 바륨(Ba)과 요오드(I) 등은 우수한 차폐능을 가지고 있지만, 30keV 근처의 에너지 영역에서 특성 X선을 방출하는 특성을 가지고 있다. 환자나 방사선 종사자의 경우 차폐체를 인체에 접촉하고 있는 경우가 많으므로 차폐체에서 발생되는 특성 X선이 인체에 직접 조사되어 방사선 피 폭을 증가시킬 위험이 매우 높다. 본 연구에서는 바륨(Ba)과 요오드(I)등에서 발생되는 특성 X선을 제거하기에 적절한 이중구조 차폐체를 방사선 수송코드 중 하나인 FLUKA 수송코드를 개발하여 선행연구로서 진행된 MCNPX 시뮬레이션과 비교 분석하여 이중구조 차폐체의 차폐율에 대한 신뢰성을 검증하고자 하였다. MCNPX와 FLUKA를 이용하여 황산바륨(BaSO4)과 산화비스무스(Bi2O3)로 이루어진 다양한 두께조합의 이중구조 차폐체를 설계하였으며, IEC61331-1에 제시된 모식도를 기하학적으로 동일하게 시뮬레이션 상에 구현하였다. 또한, 120 kVp의 연속 X선 스펙트럼에 대한 차폐체의 투과스펙트럼과 흡수선량을 납과 비교 평가하였다. 평가결과, 0.3mm-BaSO 4 /0.3mm-Bi2O3와 0.1mm-BaSO4 /0.5 mm-Bi2O3 구조에서는 33keV와 37keV의 특성 X선을 모두 흡수하였으며, 90 keV 이상의 고에너지 X선에 대해서도 납과 거의 유사한 차폐효율을 보였다. 또한, FLUKA의 수송코드는 33keV 이하에서는 cut-off 가 발생하여 저에너지 X선 광자에 대한 전산모사에 제약이 있지만, 40keV 이상의 고에너지 영역에서 MCNPX와의 상대오차가 6% 이내로 신뢰성이 매우 우수하다는 것을 확인할 수 있었다. In the current medical field, lead is widely used as a radiation shield. However, the lead weight is very heavy, so wearing protective clothing such as apron is difficult to wear for long periods of time and there is a problem with the danger of lethal toxicity in humans. Recently, many studies have been conducted to develop substitute materials of lead to resolve these problems. As a substitute materials for lead, barium(Ba) and iodine(I) have excellent shielding ability. But, It has characteristics emitting characteristic X-rays from the energy area near 30 keV. For patients or radiation workers, shielding materials is often made into contact with the human body. Therefore, the characteristic X-rays generated by the shielding material are directly exposured in the human body, which increases the risk of increasing radiation absorbed dose. In this study, we have developed the FLUKA transport code, one of the most suitable elements of radiation transport codes, to remove the characteristic X-rays generated by barium or iodine. We have verified the reliability of the shielding fraction of the structure of the structure shielding by comparing with the MCPDX simulations conducted as a prior study. Using the MCNPX and FLUKA, the double layer shielding structures with the various thickness combination consisting of barium sulphate (BaSO 4 ) and bismuth oxide(Bi 2 O 3 ) are designed. The accuracy of the type shown in IEC 61331-1 was geometrically identical to the simulation. In addition, the transmission spectrum and absorbed dose of the shielding material for the successive x-rays of 120 kVp spectra were compared with lead. In results, 0.3 mm-BaSO 4 /0.3 mm-Bi 2 O 3 and 0.1 mm-BaSO 4 /0.5 mm-Bi 2 O 3 structures have been absorbed in both 33 keV and 37 keV characteristic X-rays. In addition, for high-energy X-rays greater than 90 keV, the shielding efficiency was shown close to lead. Also, the transport code of the FLUKA’s photon transport code was showed cut-off on low-energy X-rays(below 33keV) and is limited to computerized X-rays of the low-energy X-rays. But, In high-energy areas above 40 keV, the relative error with MCNPX was found to be highly reliable within 6 %.

국가연구개발사업 공통적용 법률 제정방안

양승우(Seung Woo Yang),홍성주(Sung Joo Hong),이명화(Myong-Hwa Lee),김재경(Jae Kyung Kim) 과학기술정책연구원 2016 정책연구 Vol.- No.-

It is an undeniable truth that scientific technique nowadays, not as a current issue, but as an issue of the future, has economic and social influences nationally or globally, and as Intellectual Property Rights is becoming to be considered as a major component in evaluation of national competitiveness and economic growth, creation and utilization of knowledge based on creativity in regard to national science and technology policies is becoming an issue. Though Korea has yielded profound research achievements in quantitative aspect with consistent and daring investment to national R&D project, qualitative aspect is yet unsatisfactory when compared to that of advanced countries, and creative utilization and commercialization of research accomplishments is poor. Such problem is due to: current legislation on science and technology focused on management which makes researchers to focus on achievable studies rather than creative and challenging studies; involvement of multiple central governments and parties in R&D legislations which crafts legal systems with complicate interest; incoherence among law systems of competent authorities. Therefore, this study analyzes current laws related to national R&D projects for cultivation of high-quality research achievements from national R&D projects and improvement of support system to encourage utilization and commercialization of the achievements from the perspective of National Innovation System and ‘systemization of science and technology laws’ and reviews the necessity of R&D system reform based on the analysis. Also, this study has attempted to deduce issue on plans to improve legal system for innovation and support of national R&D project by comparing preceding studies and relevant foreign laws and thus, analysis on legal system related to R&D support and utilization and commercialization of research achievements according to competent authorities or politic parties has been conducted. Furthermore, the study provides alternative policies to improve problems of related laws based on data acquired from analysis of law, so that it can be used as reference for future legislation process. Our science and technology policies in 2016 now stand for a new era of transition. It is anticipated that this study can be an important sight for improvement of Korean science and technology policies. Finally, it must be mentioned that the perspectives in this report is solely that of the author and not a formal standpoint of the institute.

다공판 유로 내의 유동한계(CCFL)에 대한 실험적 연구

양승우(Seung-Woo Yang),이진기(Jin-Ki Lee),권정태(Jeong-Tae Kwon),김상녕(Sang Nyung Kim),강용태(Yong Tae Kang) 대한설비공학회 2007 설비공학 논문집 Vol.19 No.2

??A set of experiments of counter-current flow limit (CCFL) was performed to improve the drawbacks of Wallis I correlation which neglected the effects of channel size, channel length, injection method and the boundary conditions at the inlet of liquid and gas phase. In this study, CCFL was observed by changing the shape of porous plate using air and water. The results show that as the size of porous increases, CCFL with a round shape of the porous plate start to disappear. In this study, the CCFL correlation was calculated and the corresponding CCFL map was developed based on the experimental results.

파워엘리트 주거지의 풍수지리학적 특성 해석

양성규(Sung Kyu Yang),양승우(Seung Woo Yang) 서울연구원 2015 서울도시연구 Vol.16 No.1