클래드강 맞대기 용접부의 후열처리 유지시간에 따른 델타 페라이트 거동

박재원,이철구,Park, Jae-Won,Lee, Chul-Ku 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.2

Recently, in order to enhance the function and usefulness of products, cladding of dissimilar materials that maximizes the performance of the material is being widely used in all areas of industry as an important process. Clad steel plate, produced by cladding stainless steel plate, an anticorrosive material, on carbon steel plate, is being used to produce pressure vessels. Stainless steel plate has good corrosion resistance, and carbon steel plate has good rigidity and strength; clad steel can satisfy all of these qualities at once. This study aims to find the ${\delta}$-ferrite behavior, mechanical properties, structure change, integrity and reliability of clad steel weld on hot rolled steel plates. For this purpose, multi-layer welding, repair welding and post weld heat treatment were implemented according to welding procedure specifications (WPS). In order to observe the mechanical properties and toughness of clad steel weld zone, post weld heat treatment was carried out according to ASME Sec. VIII Div.1 UW-40 procedure for post weld heat treatment. With heat treatment at $625^{\circ}C$, the hold time was used as the process variable, increased by intervals that were doubled each time, from 80 to 1,280 min. The structure of weld part was typical cast structure; localized primary austenite areas appeared near central vermicular ferrite and fusion line. The heat affected zone showed rough austenite structure created by the weld heat input. Due to annealing effects of heat treatment, the mechanical properties (tensile strength, hardness, impact value) of the heat affected area tended to decrease. From the results of this study, it is possible to conclude the integrity of clad steel welds is not affected much in field welding, repair welding, multi-layer welding, post weld heat treatment, etc.

국내 시판 땅콩 및 땅콩버터 중 Aflatoxin $B_1$ 오염 분석

박재원,Park, Je-Won 한국식품과학회 2006 한국식품과학회지 Vol.38 No.2

식용 땅콩 40점(국산 28점, 수입산 12점)과 땅콩버터 30점(국산 12점, 수입산 18점)등 2003년 서울에서 무작위 선정된 총 70점의 국내 시판 중인 땅콩 및 그 가공품을 대상으로 aflatoxin $B_1$의 오염을 조사하였다. 본 곰팡이독소의 분석에는 형광검출 HPLC 방법이 사용되었고, 그 오염의 확인에는 HPLC-MS가 이용되었다. 두 가지 대표 시료들에 2 ppb수준으로 첨가된 aflatoxin $B_1$의 회수율은 모두 80% 이상으로 양호하였다. 또한 사용된 두 분석법 즉, HPLC-FD와 HPLC-MS의 검출한계는 각각 0.8과 0.1 ppb로 나타났다. 총 40점의 땅콩 중 10점(국산 4점, 수입산 6점)에서 aflatoxin $B_1$의 오염이 확인되었고, 국산 및 수입산 땅콩의 평균오염수준은 각각 19와 32 ppb이었다. 한편 aflatoxin $B_1$은 총 5점의 땅콩버터에서 검출되었고, 평균 오염수준이 국산과 수입산 땅콩버터 각각 10과 12 ppb이었다. 수입산 땅콩의 경우 aflatoxin $B_1$의 오염도가 보다 빈번히 나타났고, 특히 그 오염수준은 땅콩버터와는 다른 통계적으로 유의한 차이(p<0.05)를 지적하였다. 본 실험의 결과, 땅콩 및 땅콩버터는 한국인의 aflatoxin $B_1$ 노출에 있어서 주요 기여식품이 아님을 확인할 수 있었다. Aflatoxin $B_1$ in 70 retail samples, including 40 food-grade peanut (28 domestic, 12 imported) and 30 peanut butter (12 domestic, 18 imported) samples, was analyzed by high-performance liquid chromatography (HPLC) with fluorescence detection (FD), and positive samples were confirmed using HPLC with mass spectrometry (MS). Recoveries of aflatoxin $B_1$ spiked at 2 ppb exceeded 80% in both commodities. Detection limits for aflatoxin $B_1$ by HPLC-FD and MS analysis were 0.8 and 0.1 ppb, respectively. Four domestic and six imported peanut samples contained detectable levels of aflatoxin $B_1$ with means of 19 and 32 ppb, respectively. Aflatoxin $B_1$ was found in two domestic and three imported peanut butter samples with mean aflatoxin $B_1$ of 10 and 12 ppb, respectively. Peanut commodity showed more frequent aflatoxin $B_1$ contamination compared to its processed peanut butter product, and levels of aflatoxin $B_1$, especially in imported peanuts, were significantly (p<0.05) higher than those of other commodities. These results suggest peanut and peanut butter are not major contributors to dietary intake of aflatoxin $B_1$ in South Korea.

병원 경영진단

박재원,Park, Jae-Won 대한병원협회 1989 대한병원협회지 Vol.18 No.3

열간압연 클래드강의 맞대기용접부 내식성 및 용접성 평가

박재원,이철구,Park, Jae-Won,Lee, Chul-Ku 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.5

We have investigated the traits of clad metals in hot-rolled clad steel plates, including the sensitization and mechanical properties of STS 316 steel plate and carbon steel (A516), under various specific circumstances regarding post heat treatment, multilayered welds, and thick or repeated welds for repair. For evaluations, sectioned weldments and external surfaces were investigated to reveal the degree of sensitization by micro vickers hardness, tensile, and etching tests the results were compared with those of EPR tests. The clad steel plates were butt-welded using FCAW and SAW with the time of heat treatment as the variable, a that was conducted at $625^{\circ}C$, for 80, 160, 320, 640, and 1280 min. Then, the change in corrosion resistance was evaluated in these specimens. With carbon steel (A516), as the heat treatment time increased, the annealing effect caused the tensile strength to decrease. The micro-hardness gradually increased and decreased after 640 min. The elongation and contraction of the area also increased gradually. The oxalic acid etch test and EPR test on STS316 and the clad metal showed STEP structure and no sensitization. From the test results on multi-layered and repair welds, it could be concluded that there is no effect on the corrosion resistance of clad metals. The purpose of this study was to suggest some considerations for developing on-site techniques to evaluate the sensitization of stainless steels.

병렬과 영역분할을 이용한 폭발하중을 받는 철근콘크리트패널의 해석

박재원,윤성환,박대효,Park, Jae-Won,Yun, Sung-Hwan,Park, Tae-Hyo 한국전산구조공학회 2011 한국전산구조공학회논문집 Vol.24 No.4

병렬과 영역분할을 이용한 폭발하중을 받는 철근콘크리트패널의 손상을 분석하였다. 폭풍파는 극도로 짧은시간 동안에 발생되기 때문에 수치해석을 통한 결과값은 폭풍파의 메쉬크기에 영향을 받는다. 그러므로 폭풍파 메쉬크기의 영향을 분석하기 위해 explicit 유한요소해석 프로그램인 AUTODYN을 이용하여 기존 실험결과와 메쉬크기에 따른 해석결과가 비교되었다. 폭발해석결과 메쉬크기가 작을수록 정확도가 높았으나 수행시간이 증가하여 효율성이 떨어졌다. 추가로 수치해석의 효율성을 높이기 위해 영역별 Euler와 Lagrange 기법을 달리하는 병렬해석이 수행되었다. 결과로, 폭풍파영역에서는 영역분할된 Euler 메쉬를 사용하고 구조물영역에서는 영역 분할된 Lagrange 메쉬를 사용하는 것이 구조물영역에서 영역 분할된 Lagrange 메쉬만을 사용한 것보다 수치효율성이 가장 높았다. Damage of reinforced concrete panel subjected to blast load using parallel and domain decomposition is analyzed. The numerical results are sensitive to the mesh size because blast waves are generated during the extremely short term. In order to investigate the effect of mesh size on the blast wave, the analysis results from various wave mesh size using AUTODYN, the explicit finite element analysis program, were compared with existing experimental results. The smaller mesh size was, the higher accuracy was. However, in this case, the analysis was inefficient. Therefore, in order to increase numerical efficiency, the parallel analysis using decomposed method based on Euler and Lagrangian description was performed. Finally, the decomposed method using both the structure domain based on Lagrange description and the blast wave domain based on Euler description was more efficient than the decomposed method using only the Lagrange mesh on structure domain.

일반기사 - 아프리카 수단 사막고속도로 설계 프로젝트 참여기

박재원,Park, Jae-Won (사)한국토질및기초기술사회 2011 지반과 기술 Vol.8 No.2

위원회 칼럼 - 기술위원회 활동

박재원,Park, Jae-Won (사)한국토질및기초기술사회 2011 지반과 기술 Vol.8 No.4

"내가 다른 사람들에게 도움이 되는 일을 하고 있더라."

박재원,Park, Jae-Won 한국수자원학회 2022 물과 미래(한국수자원학회지) Vol.55 No.7

컴퓨터프로그램에 대한 저작권 바로 알기

박재원,Park, Jae-Won 한국전산구조공학회 2019 전산구조공학 Vol.32 No.3

Feasibility and Efficacy of Adaptive Intensity Modulated Radiotherapy Planning according to Tumor Volume Change in Early Stage Non-small Cell Lung Cancer with Stereotactic Body Radiotherapy

박재원,강민규,예지원,Park, Jae Won,Kang, Min Kyu,Yea, Ji Woon Korean Society of Medical Physics 2015 의학물리 Vol.26 No.2

이 연구는 조기 폐암의 정위방사선치료에서 육안적종양체적(Gross tumor volume, GTV) 변화에 따른 적응방사선치료(ART)의 효과 및 가능성을 보기 위해 시행되었다. 영남대학교 의료원에서 정위방사선치료를 시행한 22개의 종양을 대상으로 연구를 진행하였다. 정위방사선치료는 2주에 걸쳐 48 혹은 60 Gy를 4회에 나누어 조사하는 방법으로 시행되었다. 종양체적 변화를 측정하기 위해 매 콘빔시티마다 육안적종양체적에 대한 윤곽선 그리기를 시행하였다. 그 다음 첫 번째 콘빔시티에 기준 치료계획으로 사용할 세기조절방사선치료 계획을 시행하였다. 적응방사선치료 계획을 하기 위해, 2, 3, 4번째 콘빔시티에 기준 치료계획과 동일한 빔 각도와 제약을 적용하여 각각 재 최적화 과정을 진행하였다. 이후 적응방사선치료 계획은 기준치료계획을 각각의 콘빔시티에 복사하여 생성한 비적응방사선치료 계획과 비교되었다. 평균 육안적종양체적은 10.7 cc였다. 평균 종양체적 변화는 두 번째, 세 번째, 네 번째 콘빔시티에서 각각 -1.5%, 7.3%, 25.1%였으며 세 번째 이후 변화는 통계적으로 유의하였다(p<0.05). 하지만 두 번째 콘빔시티에서는 9개의 종양 체적이 증가하였다. 적응방사선치료 계획을 시행하였을 때, 폐에서 $V_{20\;Gy}$, $D_{1500\;cc}$, $D_{1000\;cc}$가 유의하게 감소하였으며, 흉벽에 대한 $V_{30\;Gy}$와 $V_{32\;Gy}$ 역시 유의하게 감소하였다(p<0.05). 두 번째 콘빔시티의 종양체적이 증가한 환자들에서, 기준치료 계획에 비해 적응치료방사선치료 계획을 시행하지 않았을 때, 계획용 표적체적에 대한 선량 범위 변수 중 $D_{min}$은 8.3% 감소한 반면 (p=0.021), 적응방사선치료계획을 시행한 경우에는 차이가 없었다. 이러한 결과를 보았을 때, 적응방사선치료 계획을 함으로서 표적 선량 커버는 개선시키면서 손상위험장기에 대한 선량을 감소시킬 수 있을 것이다. 그러므로, 콘빔시티를 이용한 적응방사선치료 방법은 조기 폐암의 정위방사선치료에서 고려되어야 하겠다. The purpose of this study is to evaluate efficacy and feasibility of adaptive radiotherapy according to tumor volume change (TVC) in early stage non-small cell lung cancer (NSCLC) using stereotactic body radiotherapy (SBRT). Twenty-two lesions previously treated with SBRT were selected. SBRT was usually performed with a total dose of 48 Gy or 60 Gy in four fractions with an interval of three to four days between treatments. For evaluation of TVC, gross tumor volume (GTV) was contoured on each cone-beam computed tomography (CBCT) image used for image guidance. Intensity modulated radiotherapy (IMRT) planning was performed in the first CBCT (CBCT1) using a baseline plan. For ART planning (ART), re-optimization was performed at $2^{nd}$, $3^{rd}$, and $4^{th}$ CBCTs (CBCT2, CBCT3, and CBCT4) using the same angle and constraint used for the baseline plan. The ART plan was compared with the non-ART plan, which generated copying of the baseline plan to other CBCTs. Average GTV volume was 10.7 cc. Average TVC was -1.5%, 7.3%, and -25.1% in CBCT2, CBCT3, and CBCT4 and the TVC after CBCT3 was significant (p<0.05). However, the nine lesions were increased GTV in CBCT2. In the ART plan, $V_{20\;Gy}$, $D_{1500\;cc}$, and $D_{1000\;cc}$ of lung were significantly decreased (p<0.05), and $V_{30\;Gy}$ and $V_{32\;Gy}$ of the chest wall were also decreased (p<0.05). While D min of planning target volume (PTV) decreased by 8.3% in the non-ART plan of CBCT2 compared with the baseline plan in lesions with increased tumor size (p=0.021), PTV coverage was not compromised in the ART plan. Based on this result, use of the ART plan may improve target coverage and OAR saving. Thus ART using CBCT should be considered in early stage NSCLC with SBRT.