무인비행체 비행 안전도 평가 및 정밀 시뮬레이션

박선후(SunHoo Park),이시훈(SiHun Lee),유정욱(JeongUk Yoo),신상준(SangJoon Shin) 한국항공우주학회 2020 한국항공우주학회 학술발표회 논문집 Vol.2020 No.7

동적 유입류에 의거한 무인비행체 로터의 공기역학 정밀 예측

박선후(SunHoo Park),이시훈(SiHun Lee),유정욱(JeongUk Yoo),신상준(SangJoon Shin) 한국항공우주학회 2020 한국항공우주학회 학술발표회 논문집 Vol.2020 No.11

Measurement and Simulation of the Counting Efficiency of a Whole-body Counter Using a BOMAB Phantom Inserted with Rod Sources Containing Mixed Radionuclides :

Park, MinSeok,Yoo, Jaeryong,Ha, Wi-Ho,Park, Sunhoo,Jin, Young Woo Pergamon Press 2018 Health physics Vol.114 No.3

<P>The examination of internal contamination is important for providing an adequate medical response during a radiological emergency. A whole-body counting system can assess gamma-emitting radionuclides in a human body when monitoring internal contamination. It is necessary to calibrate whole-body counting systems by using a calibration phantom, such as a Bottle Manikin Absorption phantom, to properly assess internal contamination. However, the total weight of the Bottle Manikin Absorber phantom is high, and there can be leakage of radioactive sources, which are disadvantages of using such a phantom. This study proposes a calibration phantom that is designed to overcome these disadvantages. The proposed phantom consists of rod sources that are inserted in each part of the phantom. The counting efficiency of the rod-source-inserted calibration phantom was acquired using a Monte Carlo simulation method, but the results were evaluated by comparing the experimental efficiencies with those of a conventional Bottle Manikin Absorption phantom by using two commercial whole-body counting systems (stand-up type and bed type). The efficiency curve of the rod-source-inserted phantom matched well that of the conventional calibration phantom. The relative deviation between the efficiencies of the conventional Bottle Manikin Absorption phantom and the proposed calibration phantom in both whole-body counting systems was less than 11%, and the total weight of the phantom was also reduced. These results suggest that the proposed phantom can be manipulated more easily and replace the conventional Bottle Manikin Absorption calibration phantom for these two types of whole-body counting systems.</P>

Effects of Endoscopic Variceal Ligation for the Esophageal Varix in Patients with Advanced Hepatocellular Carcinoma and Portal Vein Tumor Thrombosis

( Sun Seob Park ),( Joong-won Park ),( Bo Hyun Kim ),( Sunhoo Yoo ),( Byung-ho Nam ),( Chang-min Kim ) 대한간학회 2016 춘·추계 학술대회 (KASL) Vol.2016 No.1

Aims: The outcomes of endoscopic variceal ligation (EVL) treatment of esophageal varices in patients with hepatocellular carcinoma (HCC) and portal vein tumor thrombus (PVTT) are unclear. We evaluated the short term (7-, 15-, 30-day) outcomes of emergency and prophylactic esophageal variceal band ligation (EVL) in HCC patients with PVTT. Methods: From 2010 to 2012, 424 sessions of EVL were conducted in 242 HCC patients with esophageal varices. Clinical findings and outcomes were reviewed retrospectively. We assessed the bleeding- free and overall survival, and related prognostic factors were analyzed using the Kaplan-Meier method and a Cox proportional hazard model. Results: All EVL sessions were conducted in patients with liver function Child-Pugh class A (159 sessions, 37.5%), class B (220 sessions, 51.9%), class C (45 sessions, 10.6%), and in modified UICC stage I/II (138 sessions, 32.5%), stage III/IV (93 sessions, 21.9%). Ninety-three (21.9%) sessions were conducted in the state of complete remission of HCC. Total 172 sessions of EVL were conducted in patients with PVTT; 115 (66.9%) sessions in patients with PVTT at the main portal trunk (Vp4) or first-order branch of the portal vein (Vp3). Major PVTT (Vp4 or Vp3) was predictive of esophageal variceal bleeding (hazard ratio 8.14, p<.0001). The 7-, 15-, 30-day bleeding-free survival rates of patients with major PVTT were 91.2%, 75.0%, 56.9% and they are significantly lower than that of patients without PVTT (98.0%, 95.6%, 92.0%, p<.0001, respectively). Conclusions: After successful hemostasis with EVL, the bleeding-free survival rate was significantly lower in patients with major PVTT in comparison to patients without major PVTT. Non-invasive treatment may be first considered for esophageal varix in advanced HCC patients with main PVTT.

Influence of Alcohol Intake on the Stage and Outcomes of Hepatocellular Carcinoma

( Ji Hee Park ),( Joong-won Park ),( Bo Hyun Kim ),( Sunhoo Yoo ),( Byung Ho Nam ),( Chang-min Kim ) 대한간학회 2016 춘·추계 학술대회 (KASL) Vol.2016 No.1

Aims: Alcohol, a group 1 carcinogen, is a well-known risk factor for hepatocellular carcinoma (HCC). We investigated whether lifetime alcohol intake would be associated with the tumor characteristics or prognosis of HCC. Methods: Of 826 patients initially diagnosed with HCC at a single institution between January 2007 and December 2009, 651 patients with available documented history of alcohol intake were enrolled. The total amount of alcohol intake was calculated based on written questionnaires at the first clinic visit. Patients were categorized into 4 groups according to the etiology: Hepatitis B virus (HBV)-related (HBV+, n=462), hepatitis C virus (HCV)-related (HCV+, n=55), both HBV and HCV-related (HBV+/HCV+, n=21), and non-virus-related (HBV-/HCV-, n=110). Clinical features and prognosis were analyzed according to the presence or absence of alcohol intake or the amount of alcohol intake. Results: Of 651 patients, 431 had a history of drinking alcohol (alcohol group) and 220 had no history of drinking alcohol (non-alcohol group). There were no significant differences between the alcohol and non-alcohol groups in terms of tumor size, number of nodules, tumor stage, Child-Pugh class, or overall survival. Significant differences in tumor stage were observed between alcohol and non-alcohol groups for the HBV+ group in subgroup analysis (p=0.038): stage I (5.1% vs. 11.5%), stage II (31.3% vs. 31.5%), stage III (24.2% vs. 26.7%), stage IVa (24.6% vs. 15.8%), and stage IVb (14.8% vs. 14.6%). There were no other significant differences between the alcohol and non-alcohol groups across etiologies for HCC. The amount of alcohol intake also did not affect the tumor characteristics or prognosis of HCC. Conclusions: In this cohort, the non-alcohol group of HBV-related HCC patients tended to have more stage I and less stage IVa diagnosis. However, there was no significant difference in tumor characteristics, Child-Pugh class, or overall survival according to the history or amount of alcohol reported in the questionnaire.

³²P measurement and dose conversion factor evaluation of activated human hair by criticality accident

Yoon, Seokwon,Ha, Wi-Ho,Park, Seyoung,Shin, Seongwook,Yoo, Jaeryong,Park, Sunhoo,Lee, Seung-Sook Nuclear Technology Publishing 2014 Radiation Protection Dosimeetry Vol.161 No.1

<P>In order to conduct dose assessment of victims in criticality accidents, a method of fast neutron capture-activated <SUP>32</SUP>P measurement of hair in which samples are treated by a chemical and analytical procedure that takes 9 h and measurement is conducted by liquid scintillation counting is presented. To validate this measurement method, hair samples spiked with a <SUP>32</SUP>P reference source were measured and the results analysed and the optimal sample mass and detection efficiency were determined. To verify the correlation between <SUP>32</SUP>P-specific activity and absorbed dose for spectra with two neutron mean energies, samples collected from three normal individuals were irradiated at various neutron energies and irradiation times using the MC50 Cyclotron of the Korea Institute of Radiological and Medical Sciences. The <SUP>32</SUP>P-specific activity trend of the irradiated hair agreed well with the absorbed doses. Based on the results, dose conversion factors, which were 0.67±0.15 and 0.59±0.06 Gy (Bq g<SUP>−1</SUP>)<SUP>−1</SUP> at neutron mean energies of 2.33 and 5.36 MeV, respectively, were calculated as a guide for medical treatment of criticality accident victims.</P>