Marx 고전압 펄스 발생장치의 제작 및 동작특성에 관한 연구

정운관,육종철 慶熙大學校 1984 論文集 Vol.13 No.-

This study is to investigate the operating characteristics of a Marx high voltage pulse generator, which is designed and fabricated for the purpose of constructing a linear theta-pinch plasma generating facility. The Marx generator consists of a 2 kJ capacitor bank of maximum output voltage of 200kV, a set of main spark switch, a triggring system, and high voltage charging power supply. The experimental results show that the operating characteristics of the generator can be controlled through varying nitrogen pressure as a filling gas. The output pulse of the generator is achieved close to the estimated voltage with the rise time of 3 μ seconds. The stability of the generator is also very satisfactory within operating range of main spark switch.

A Study on the Reproducibility of the Volume in 3-D Volume-rendering Images for Radiation Treatment Planning

정운관,박형후,유윤식,임인철,이재승,구은회,김성환,김문집,권대철,동경래,김영재,조재환 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.4

This study examined the effects of a change in the reconstruction cross-section, which depends on the slice thickness and the phantom shape, on the volume changes in a three-dimensional volume-rendering image reconstructed in a computed tomography (CT) simulation. For this, precise phantoms with different shapes and sizes were manufactured, and the three-dimensional volumerendering images obtained from computed treatment planning for a phantom were measured. The CT simulation, which had been standardized using a phantom, was implemented with slice thicknesses of 1.25, 2.5, 5, and 10 mm. The measurements were performed on the X-axis, the Y-axis and the Z-axis for the accessory phantom to identify the following changes: length, area and volume, measurement deviation between analyzers, and maximum and minimum values. With increasing slice thickness the difference in the visual error range between analyzers increased, the cross section for the scan increased, and the thickness or density in the scan direction became nonuniform. These results are expected to help analyze the cause of the error in digitally-reconstructed radiographs and establish a more precise CT simulation.

REDD+ 활동이 사회적 자본을 통해 빈곤 완화에 미치는 영향 : 미얀마 REDD+ 시범사업을 중심으로

정운관,이찬중,이요한 한국국제농업개발학회 2023 韓國國際農業開發學會誌 Vol.35 No.2

This study aimed to analyze the effects of REDD+ activities such as education, cookstove incentives and Community Forestry (CF) membership on poverty alleviation through the mediating effects of social capital, including network, trust, cooperation and social inclusion. We collected data through a field survey from randomly selected 335 households in the REDD+ pilot sites, including Kyauktaga and Minhla townships in Bago Province, Myanmar. The relationship between variables was analyzed using Structural Equation Model (SEM). The results showed that social capital has significant impact on poverty reduction. Specifically, social inclusion showed a direct impact on poverty reduction. While REDD+ activities such as education and CF membership had impacts on income generation, the impacts were insufficient to realize poverty alleviation. Forest dependents are relatively poor, which implies that forest activities are limited in achieving poverty alleviation through income level improvement. We found that the intervention of the REDD+ program on local communities may contribute to the accumulation of social capital, thereby reducing poverty.

Statistical-techniques-based Computer-aided Diagnosis (CAD) Using Texture Feature Analysis: Application in Computed Tomography (CT) Imaging to Fatty Liver Disease

정운관,박형후,임인철,이재승,구은회,동경래 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.5

This paper proposes a computer-aided diagnosis (CAD) system based on texture feature analysis and statistical wavelet transformation technology to diagnose fatty liver disease with computed tomography (CT) imaging. In the target image, a wavelet transformation was performed for each lesion area to set the region of analysis (ROA, window size: 50 × 50 pixels) and define the texture feature of a pixel. Based on the extracted texture feature values, six parameters (average gray level, average contrast, relative smoothness, skewness, uniformity, and entropy) were determined to calculate the recognition rate for a fatty liver. In addition, a multivariate analysis of the variance (MANOVA) method was used to perform a discriminant analysis to verify the significance of the extracted texture feature values and the recognition rate for a fatty liver. According to the results, each texture feature value was significant for a comparison of the recognition rate for a fatty liver (p < 0.05). Furthermore, the F-value, which was used as a scale for the difference in recognition rates, was highest in the average gray level, relatively high in the skewness and the entropy, and relatively low in the uniformity, the relative smoothness and the average contrast. The recognition rate for a fatty liver had the same scale as that for the F-value, showing 100% (average gray level) at the maximum and 80% (average contrast) at the minimum. Therefore, the recognition rate is believed to be a useful clinical value for the automatic detection and computer-aided diagnosis (CAD) using the texture feature value. Nevertheless, further study on various diseases and singular diseases will be needed in the future.

필름뱃지의 개인선량평가 알고리즘 개발

정운관,백승진,박재덕 조선대학교 에너지.자원신기술연구소 2000 에너지·자원신기술연구소 논문지 Vol.22 No.2

The purpose of this paper is to develop dose evaluation algorithm for film badge and describe the results of the personnel dosimetry performance test in KINS. Reference radiations irradiate seven categories, except the neutron category prescribed in the ANSI N13.11-1993, and evaluation algorithm have been obtained from dose characteristic curves. The performance criterion in a given category, sum of the absolute value of the bias and the standard deviation value of the performance quotient, were estimated by the use of film badge algorithm and dose equivalents according to the standard method. As a result, the performance index in a given category showed a good agreement less than tolerance level, for the deep and shallow dose equivalents or absorbed dose Development algorithm can be used for dose evaluation of film-badge personnel dosimetry.

Development of Off-Site Dose Calculation Program Due to Liquid Effluents from Nuclear Facilities Located in Inland Area

정운관,염정민,황원태,한문희 대한방사선방어학회 2002 방사선방어학회지 Vol.27 No.4

- 우리나라의 농업, 환경적 요소를 고려하여 내륙지역에 위치한 원자력시설의 운영으로 발생되는 액체상 방류물에 의한 주민선량 평가 프로그램을 개발하였다. 이를 위해 내륙지역에 대한 적절한 피폭경로 설정 및 수학적 모델링 수립, 부지 특성 입력 변수값 설정 등 일련의 연구가 수행되었다. 개발된 프로그램에 대한 시험을 우라늄 계열 핵종을 방출하는 원전연료가공시설에 대해 적용하였다. 평가 결과, 피폭선량에 대한 기여는 하천수의 관개에 의한 농축산물 오염이 가장 높았다. 유효선량에 대한 결정 연령군은 소아, 결정 장기는 뼈로 나타났다.

Why Social Capital Matters for the Success of REDD+ Programs

정운관,우희성,이요한 인간식물환경학회 2022 인간식물환경학회지 Vol.25 No.2

Background and objective: We quantitatively estimated the impact of social capital on poverty reduction using a surveyconducted on 335 randomly selected households in 6 villages running REDD+ programs in Bago Province, Myanmar. Ourcentral question is whether the effectiveness of REDD+ programs is associated with social capital, including networks,trust, cooperation, and social inclusion. Methods: We developed a tool to measure social capital while considering forest conservation activities, and quantitativelyanalyzed the impact of social capital on poverty levels in 6 villages running REDD+ programs in Myanmar. Results: Our results reveal that social capital has a significant effect in alleviating household poverty in Myanmar. Thus,investment in social capital may help alleviate poverty. REDD+ training participants and community forestry membersshowed a relatively higher level of social capital than those who did not participate. We also found that forest dependentswere statistically significantly more likely to live in poverty, which implies that socially marginalized residents tend to relymore on forests and that collecting forest products has limited effects on overcoming poverty. Conclusion: The local strategy for implementing REDD+ programs should target community forestry members to promotetheir social capital by supporting forest tenures and benefit sharing among marginalized people.

Si, PIN 광 다이오드를 이용한 플라즈마 가열구조의 해석

정운관,우승웅,육종철 조선대학교 원자력연구소 1990 原子力硏究 Vol.4 No.-

This study is to investigate the heating mechanism of a produced plasma by theta pinch device. The temperal and spatial dependency of pulse magnetic field is measured by a magnetic probe, which is inserted into three different positions in the plasma tube. The transformation of wavelength in plasma light is measured by a Si-PIN photodiode at the various plasma tube pressures. The experimental results show that the largest plasma current and light signal occurred at the initial pressure of 2.5X10^-2 mmHg and the magnetic field cannot be penetrated into the center of the plasma column.

필름배지선량계에 의한 개인피폭선량 측정에 관한 연구

정운관 대한방사선 방어학회 1994 방사선방어학회지 Vol.19 No.1

X-선과 감마선의 에너지에 따른 선질특성과 선량 및 필름의 사진농도와의 관계를 이용한 필름배지선량계의 선량환산식을 실험적으로 체계화 하였고, 시간경과에 따른 잠상퇴행 특성과 방사선의 입사방향에 따른 방향특성을 실험적으로 조사하여 보정계수를 산출하였다. 본 연구에서 구한 선량환산식은 필름배지선량계의 기술기준인 성능판정 기준을 잘 만족시키는 것으로 나타났다. The experimental evaluation of exposure conversion formula using the relationship between optical photo-density, exposure dose and the quality of radiation characteristics of radiation energy to X-ray and γ-rays. The film badge dosimeter is analyzed by exposure conversion formula which evaluate image fading characteristics for development time and directional characteristics for incident beam angle. In conclusion, exposure conversion formula evaluated of this study is satisfied with quality decision criterion of he film badge dosimeter.

개인피폭선량 알고리즘의 평가

정운관,심재학,김영진 조선대학교 에너지.자원신기술연구소 2004 에너지·자원신기술연구소 논문지 Vol.26 No.2

This paper describes experimental evaluation of exposure dose algorithm for film badge and the results of the personnel dosimetry performance test. Reference radiations irradiate seven categories, except the neutron category prescribed in the ANSI N13.11-1993. The performance criterion in a given category, sum of the absolute value of the bias and the standard deviation of the performance quotient, was estimated by the use of film badge algorithm and dose equivalents according to the standard method. As a result, the performance index in a given category showed a good agreement less than tolerance level, for the deep and shallow dose equivalents or absorbed dose, and this study is satisfied with quality decision cnterion of the film badge personnel dosimeter and intercomparison results.