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- 저자 : 방성호(Sung Ho Bang) (검색결과 17 건)
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방성호(Sung-Ho Bang),이진원(Jin-Won Lee),김태원(Tae-Won Kim) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.6
본 연구에서는 급수 순환 시스템 중 동작 유체의 이송을 위해 사용하는 배관을 대상으로 관로 크기 및 고온 급수 환경에 따른 침식-부식 거동과 그 영향을 규명하고자 하였다. 이를 위해 일반적인 관로 소재인 철과 핵심 부식 인자인 산소의 화학반응식을 기반으로 Hayduk 과 Minhas 가 제안한 모델을 이용하여 침식-부식 해석을 실시하였다. 상용 유한요소해석 프로그램인 ABAQUS 를 사용하여 해석을 수행하였으며 배관의 직경 및 급수 온도를 변화시킴에 따른 침식-부식률을 평가할 수 있었다. 결과를 통해 급수 온도가 침식-부식률에 가장 큰 영향을 미치는 요인이 됨을 알 수 있었으며, 특히 290℃ 급수에 노출된 스테인리스 316 강은 연간 2.59 ㎛의 두께 손실이 발생할 것으로 예상되었다. In this study, we tried to define the erosion-corrosion behavior together with the resulting effects on a pipe that is a part of a feed water circulation system according to the pipe size and hot feed water environment. An erosioncorrosion analysis was performed through the Hayduk and Minhas model based on the chemical reaction between iron and oxygen, an essential corrosive factor. The erosion-corrosion rate against the pipe diameter and feed water temperature was then evaluated by means of finite element analysis using ABAQUS. As shown in the results, the feed water temperature was the main factor influencing the erosion-corrosion rate; in particular, it was expected that the thickness of 316 stainless steel would decrease by 2.59 ㎛ every year in a hot water environment at 290℃.
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복부 CT 검사 시 여성의 유방과 남성의 고환에 대한 조직 흡수선량과 화질 평가 : Beam Collimation과 Pitch의 변화를 중심으로
방성호(Sung Ho Bang),김문찬(Moon Chan Kim),남윤철(Yoon Chul Nam) 대한전산화단층기술학회 2011 대한CT영상기술학회지 Vol.13 No.2
목적 Overscanning length는 beam collmation과 pitch의 변화에 따라 큰 변화가 있다. 따라서 이러한 overscanning의 증가는 실제로 영상화가 필요한 부분 외의 조직에 위험을 증가시킬 수 있다. 본 연구의 목적은 복부 CT 검사 시, overscanning dose로 인한 여성의 유방과 고환의 조직 흡수 선량을 측정과 화질 평가를 통해 합리적인 복부 CT 검사의 방법을 권고하고자 하였다. 대상 및 방법 GE VCT XT장치를 사용하여 인체 모형 팬텀에 조합된 형광유리선량계를 배열하여 각각의 beam collimation과 pitch 조합에 따른 overscanning dose을 측정하였으며, 이때 사용한 beam collimation과 pitch의 조합은 20mm beam collimation에서는 0.969 pitch와 1.375 pitch를 40mm beam collimation에서는 0.984 pitch와 1.375 pitch를 사용하였다. 같은 조합으로 ACR phantom을 이용한 화질 평가를 실시하였다. 결과 Beam collimation과 pitch가 증가할수록 overscanning length는 증가하였으며, 여성 유방의 심부 선량에서는 40mm beam collimation과 0.984 pitch의 조합이 가장 영향이 컸다. 남자 고환의 표면 선량에서는 40 mm beam collimation과 1.375 pitch의 영향이 가장 컸다. 화질은 beam collimation과 pitch가 증가할수록 떨어졌다. 결론 각각의 beam collimation과 pitch의 조합은 장점과 단점을 동시에 가지고 있으며, 환자의 상태에 따라 최적화된 CT protocol을 선택해야 환자 피폭선량 경감과 화질 개선에 유리할 수 있다. I. Purpose Overscanning length change to variation of beam collimation and pitch. Therefore being overscanning length increase adjacent organ risk in radiation. The purpose of our study was to evaluation of breast, gonad dose and image quality in abdomen CT examination changing of beam collimation and pitch. Finally, this study recommends reasonable abdomen CT examination. II. Meterial and Methods We evaluated the effect of overscanning length with change of scan parameter such as beam collimation and pitch factor in GE VCT XT 64 MDCT. We used 20 mm and 40mm beam collimation also 0.984 and 1.375 pitch (but 0.969) pitch in case 20 mm beam collimation). We measured radiation dose in breast and gonad region for glass dosimeter. Also we measured image quality for ACR CT phantom. III. Result As beam collimation and pitch increase, overscanning length increase too. Breast organ dose was great effect in combination of 40 mm beam colllination and 0.984 pitch. As this time range of dose in overscanning length was about 40 mm. Gonad organ dose was great effect in combination of 40 mm beam collimation and 1.375 pitch. As this time range of dose in overscanning length was about 45 mm. Image quality degenerated as beam collimation and beam pitch increased by. IV. Conclusions With increases beam collimation and pitch, overscanning dose increases. Respectively, combination of beam collimation and pitch have both merits and demerits. Therefore, we must select optimal CT protocol on patient’s condition.
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산업용 회분식 반응기에서의 반응열 측정과 응용에 관한 연구
방성호(Sung Ho Bang),이용수(Yong Soo Lee),이석호(Seok Ho Yi),이광순(Kwang Soon Lee) 대한전자공학회 1992 대한전자공학회 학술대회 Vol.1992 No.10
In operational point of view, the batch reactor is quite different from the continuous reactor in that it is completely in unsteady states. This makes process variables swing over wide ranges and the process disclose its nonlinearities. For the most part these nonlinearities are due to reaction heat. Accordingly it is very important to know the informations of reaction heat. This paper presents the method of reaction heat measurement in industrial batch reactor which furnishes the limited measurable points. The informations of reaction heat are utilized in modeling of the batch reactor as well as deciding the stability and control variables.
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복부 CT검사에서 Scan Field of View 선택이 선량과 화질에 미치는 영향에 관한 연구
권용락(Yong Rak Kwon),방성호(Sung Ho Bang),남윤철(Yoon Chul Nam),김문찬(Moon Chan Kim) 대한전산화단층기술학회 2012 대한CT영상기술학회지 Vol.14 No.2
목적 현재 보편화되는 CT장치들은 다양한 bow-tie filter와 SFOV를 부가적으로 설치하고 있다. 이에 복부 CT검사에서 다양한 SFOV와 bow-tie filter를 변화시켜서 선량과 화질에 미치는 영향을 알아보고 최적의 검사방법을 권고하고자 하였다. 대상 및 방법 CT장치는 GE LightSpeed VCT XT와 Toshiba Aquillion 64MDCT을 사용하였다. 선량 측정은 Rando anthropomorphic woman phantom과 형광유리선량계를 사용하여 phantom 내ㆍ외측에서 측정을 하였으며 화질 평가는 각 장비의 자체 software을 사용하여 phantom 내측(3시, 9시, 12시, 중앙) 위치에서 noise을 측정하였다. X축의 직경 30cm인 phantom의 단면을 사용하여 GE사의 장치에서 SFOV을 small, medium, large로, Toshiba사의 장치에서는 SFOV을 medium, large로 변화시켜 평가하였다. X축의 직경 34cm인 phantom의 단면에서는 GE사의 SFOV을 medium, large로 변화시켜 평가하였다. 결과 LightSpeed VCT XT장치로 직경 30cm인 단면에서는 small SFOV 적용 시 선량 및 noise 값이 가장 낮게 측정되었고 직경 34cm인 단면에서는 선량 차이가 거의 없었으나 large SFOV 적용 시 조금 높았으며 noise 값은 medium SFOV 적용 시 낮게 측정되었다. Toshiba Aquillion 장치로 직경 30cm인 단면에서는 선량이 large SFOV 적용 시 크게 높았으나 noise 값은 12시 방향을 제외하고는 큰 차이가 없었다. 결론 환자의 크기에 따른 적절한 SFOV 선택은 환자의 피폭을 경감하고 진단에 적합한 우수한 영상을 획득하는 것이 옳은 검사방법이라고 사료된다. I. Purpose Current conventional CT equipments have various bow-tie filter and SFOV additionally, We studied the effect of a radiation dose and an image noise depending on a various SFOV and bow-tie filter and suggest the optimized method. II. Meterial and Methods The CT equipments are supplied by GE LightSpeed VCT XT and Toshiba Aquillion 64MDCT. The radiation dose has measured at the external and inner positions using the Rando anthropomorphic woman phantom and the fluorescent glass dosimeter. The image noise has evaluated at the inner positions (3, 9, 12 o’clock and middle) of a phantom’s cross section by the equipment’s software. The 30 cm diameter of X-axis has been scanned by small, medium, large SFOV of GE and medium, large SFOV of Toshiba. For the 34 cm diameter of X-axis, medium, large SFOV of GE has been. III. Result The lowest values of dose and noise have obtained by the light speed VCT XT for 30 cm of the object size at a small SFOV. The 34 cm of object size has almost none of differences dose though a higher dose at large SFOV and a lower noise at medium SFOV are shown. In Toshiba Aquillion, a dose at large SFOV is largely high for 30 cm of object size and a noise has no difference except the direction of 12 o’clock. IV. Conclusions We concluded that the optimized SFOV for the size of patients can reduce the radiation dose and help to obtain the good image for examinations.
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Adaptive Statistical Iterative Reconstruction 기법의 적용에 따른 Computed Tomography 영상의 화질과 선량 연구
박건진(Kun Jin Park),방성호(Sung Ho Bang),김문찬(Moon Chan Kim),한동균(Dong Kyoon Han) 대한CT영상기술학회 2010 대한CT영상기술학회지 Vol.12 No.1
Purpose Recently many studies had been applied to minimize radiation exposure while also obtaining suitable image quality for diagnosis. This study was focused on the evaluation of image quality and dose of CT image which were applied with adaptive statistical iterative reconstruction(ASIR) to examine the usefulness of image diagnosis. Materials and methods CT scans were performed with a 64-slice MIDCT scanner(GE LightSpeed VCT XTe, waukesha, Wisconsin, USA). CTDI measurement was used for comparing doses while the ACR Phantom was used for image quality comparison. The ASIR was used for image reconstruction which create a noise map based on the filtered backprojection(FBP) and organized a statistical model and blends it with appropriately original FBP image. For image quality comparison in phantom study, CTDIVOL 14.76 mGy for non-ASIR was applied and evaluations were clone by analyzing items such as noise level, olv-contrast and high-contrast resolution. In patient study, test were clone by CTDIVOL 9.45 mGy (standard chest CT dose) and 0.90 mGy, 0.45 mGy, and 0.36 mGy(low dose CT) were delivered with standard and bone kernel. Results In phantom study showed that the upward values of spatial resolution were generally similar among kernels and low-resolution kernels showed excellence of contrast to noise(CNR) above 1.0 compared to high-resolution kernels in ASIR 50 and showed improved CNR even though decreased of dose 40% above. With same Parameters noise level(NL) showed 2% in FBP image, 1.5% in ASIR 30% above, and 1% or less in ASIR 100%. Differentiating by the naked eye was difficult, but the differences between each kernel of ASIR were recognized by measuring resolution and noise by quantitative analysis. The effective dose of the low-dose chest examination held as a patient study was only 0.3 mSv or less. It showed reduction of 90% compared to the standard dose, and similar image quality was maintained by applying ASIR 30~60%. However, high-resolution kernels With high ASIR showed a severe level of noise including streak artifacts. Conclusion CT image reorganization using ASIR is considered to be a useful dose reducing method while maintaining the image quality, when comparing with the existing filtered back-projection (FBP) reorganized images.
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