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TRISO 입자를 포함하는 SiC 복합소결체의 소결 및 특성 평가
이현근,김대종,박지연,김원주,Lee, Hyeon-Geun,Kim, Daejong,Park, Ji Yeon,Kim, Weon-Ju 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.5
Fully ceramic micro encapsulated (FCM) nuclear fuel is a concept recently proposed for enhancing the stability of nuclear fuel. FCM nuclear fuel consists of tristructural-isotropic (TRISO) fuel particles within a SiC matrix. Each TRISO fuel particle is composed of a $UO_2$ kernel and a PyC/SiC/PyC tri-layer which protects the kernel. The SiC ceramic matrix is created by sintering. In this FCM fuel concept, fission products are protected twice, by the TRISO coating layer and by the SiC ceramic. The SiC ceramic has proven attractive for fuel applications owing to its low neutron-absorption cross-section, excellent irradiation resistivity, and high thermal conductivity. In this study, a SiC-matrix composite containing TRISO particles was sintered by hot pressing with $Al_2O_3-Y_2O_3$ additive system. Various sintering conditions were investigated to obtain a relative density greater than 95%. The internal distribution of TRISO particles within the SiC-matrix composite was observed using an x-ray radiograph. The fracture of the TRISO particles was investigated by means of analysis of the cross-section of the SiC-matrix composite.
핵연료 피복관용 다중층 SiC 복합체 튜브의 Hoop Stress 전산모사 연구
이현근,김대종,박지연,김원주,Lee, Hyeon-Geun,Kim, Daejong,Park, Ji Yeon,Kim, Weon-Ju 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.5
Silicon carbide-based ceramics and their composites have been studied for application to fusion and advanced fission energy systems. For fission reactors, $SiC_f$/SiC composites can be applied to core structural materials. Multilayered SiC composite fuel cladding, owing to its superior high temperature strength and low hydrogen generation under severe accident conditions, is a candidate for the replacement of zirconium alloy cladding. The SiC composite cladding has to retain its mechanical properties and original structure under the inner pressure caused by fission products; as such it can be applied as a cladding in fission reactor. A hoop strength test using an expandable polyurethane plug was designed in order to evaluate the mechanical properties of the fuel cladding. In this paper, a hoop strength test of the multilayered SiC composite tube for nuclear fuel cladding was simulated using FEA. The stress caused by the plug was distributed nonuniformly because of the friction coefficient difference between the inner surface of the tube and the plug. Hoop stress and shear stress at the tube was evaluated and the relationship between the concentrated stress at the inner layer of the tube and the fracture behavior of the tube was investigated.
국소간의 자기공명영상에서 Mn-DPDP의 유용성과 적합한 MR Sequence에 관한 비교, 고찰
김은성,김대현,이현근,오근택,이순노,이우식,Kim Eun Seong,Kim Dae Hyeon,Lee Hyeon Geun,O Geun Taek,Lee Sun No,Lee U Sik 대한방사선사협회 2001 대한방사선사협회지 Vol.27 No.2
Ⅰ. Purpose : To evaluate the diagnostic value of Mn-DPDP for the detection of focal hepatic lesions on MR images and to determine the optimal pulse sequence to maximize its effect. Ⅱ. Material and Methods : Twenty-eight patients(6 women and 22 men, aged f
SiC<sub>f</sub>/SiC 복합체의 화학기상침착 거동에 미치는 권선 구조와 침착 변수의 영향
김대종,고명진,이현근,박지연,김원주,Kim, Daejong,Ko, Myoungjin,Lee, Hyeon-Geun,Park, Ji Yeon,Kim, Weon-Ju 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.5
SiC and its composites have been considered for use as nuclear fuel cladding materials of pressurized light water reactors. In this study, a $SiC_f$/SiC composite as a constituent layer of SiC triplex fuel cladding was fabricated using a chemical vapor infiltration (CVI) process in which tubular SiC fiber preforms were prepared using a filament winding method. To enhance the matrix density of the composite layer, winding patterns, deposition temperature, and gas input ratio were controlled. Fiber arrangement and porosity were the main parameters influencing densification behaviors. Final density of the composites decreased as the SiC fiber volume fraction increased. The CVI process was optimized to densify the tubular preforms with high fiber volume fraction at a high $H_2$/MTS ratio of 20 at $1000^{\circ}C$; in this process, surface canning of the composites was effectively retarded.
원자력 사고 안전성 향상을 위한 SiC<sub>f</sub>/SiC 복합소재 개발 동향
김대종,이지수,천영범,이현근,박지연,김원주,Kim, Daejong,Lee, Jisu,Chun, Young Bum,Lee, Hyeon-Geun,Park, Ji Yeon,Kim, Weon-Ju 한국복합재료학회 2022 Composites research Vol.35 No.3
SiC 섬유강화 복합체는 경수형 원자로의 안전성을 획기적으로 향상시킬 수 있는 사고저항성 핵연료 피복관 소재이다. 지르코늄 합금 피복관 및 금속기반 사고저항성 핵연료 피복관에 비해, 중대 사고 환경에서도 우수한 구조적 안정성을 가지고 부식 속도가 매우 낮아, 사고 시 원자로의 온도를 낮추고 사고 진행을 늦출 수 있다. 본 논문에서는 현재 개발되고 있는 사고저항성 SiC 복합체 핵연료 피복관의 개념 및 가동/사고환경에서의 다양한 특성, 상용화를 위해 해결해야 할 다양한 이슈에 대해서 소개하고자 한다.
(s,S)-정책하의 연속형 내부재고를 갖는 M/M/1 대기행렬모형 분석
박진수(Park Jinsoo),이현근(Lee Hyeon Geun),김종현(Kim Jong Hyeon),윤은혁(Yun Eun Hyeuk),백정우(Baek Jung Woo) 한국산업정보학회 2018 한국산업정보학회논문지 Vol.23 No.5
본 논문은 연속형 내부재고를 갖는 M/M/1 대기행렬모형을 다룬다. 고객은 포아송과정으로 도착하고 선입선출 서비스를 받는다. 각 고객의 서비스시간은 독립적이며 동일한 지수분포를 따른다. 고객은 서비스를 받기 위해 일반분포를 따르는 확률변수 H의 내부재고를 소비하며, 서비스완료시점에 감소한다고 가정한다. 재고시스템은 전통적인 (s,S)-정책에 따라 운용되며, 재고의 조달시간은 일반분포를 따른다고 가정한다. 재고가 없는 기간에 도착한 고객은 유실된다. 본 논문은 이처럼 운영되는 재고-대기행렬모형의 고객수 및 재고량에 대한 안정상태 결합확률분포를 유도하고수치예를 보인다. 또한 장기적인 비용을 최소화하는 재고운용정책을 고찰한다. This study focuses on an M/M/1 queue with an attached continuous-type inventory. The customers arrive into the system according to the Poisson process, and are served in their arrival order; i.e., first-come-first-served. The service times are assumed to be independent and identically distributed exponential random variable. At a service completion epoch, the customer consumes a random amount of inventory. The inventory is controlled by the traditional (s, S)-inventory policy with a generally distributed lead time. A customer that arrives during a stock-out period assumed to be lost. For the number of customers and the inventory size, we derive a product-form stationary joint probability distribution and provide some numerical examples. Besides, an operational strategy for the inventory that minimizes the long-term cost will also be discussed.
담관 결석 발생과 재발에 있어 십이지장 팽대부 주위 게실과의 상관관계
김상균(Sang Gyun Kim),정재연(Jae Yeon Jeong),고주영(Ju Yeong Ko),이현근(Geum Nam Kim),김금남(Hyeon Geun Lee),조영기(Young Ki Cho) 대한영상의학기술학회 2010 대한영상의학기술학회 논문지 Vol.2010 No.-
Purpose : This study was designed to assess the ERCP findings of a juxtapapillary duodenal diverticulum and with even higher rate following subsequent reoperation. However, the factors contributing to recurrent stones have not well defined. Some authors have reported on association of juxtapapillary diverticula with recurrent billiary stone. We have studied to assess the clinical significance of coexsting PAD on recurrent commonbile duct stones and to establish the rational operative procedure in primary or recurrent common duct stones with coexisting PAD. Materials and Methods : Medical records of 583 consecutive patients(May. 2006 ~ June. 2009) who performed ERCP for biliary symptoms were reviewed. We comparative study retrospectively have done between patients with and without PAD on treatment. Results : Incidence of PAD was 26.7% on ERCP, and increased in the old aged patients. Incidence of biliary stone in PAD group was higher than that of non-PAD group(73.1% vs. 52.7%), and gall stone involving common duct was more prevalent in PAD group than non-PAD group. PAD group showed higher stone recurrence rate (23.6% vs. 5.3%) and earlier recurrence following conventional treatment, and needs more multiple treatments, compared with non -PAD group. Intradiverticular papillae(IDP) type showed higher stone recurrence, compared with juxtapapillary diverticula(JPD) type (27.1% vs. 13.2%) Conclusion : PAD would be one of important contributing factors for development and recurrence of common bile duct.