武器體系紹介

이현근 해군대학 1986 海洋戰略 Vol.- No.41

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.

다의 구조와 개념론

이현근 한국현대언어학회 1999 언어연구 Vol.15 No.2

Darmesteter has already discussed about the structure of word meaning, which has been the foundation of Cognitive Semankics approach. Wittgenstein and Taylor's chain approach, Langacker's schema approach, and Lakoff's radial categories are all from him. However, the concept-base approach has two maxims: first, concept and meaning are related but separated ones, second, primary meaning and extended meaning can be divided in a word. The extended meaning, however, means that meaning extension is limited in a certain way. Conceptology has the view on polysemy structure like these (of course this is adapted to word meaning): three-dimentional, hierarchical(asymmetrical), radial.

A CONSTRAINED CONVEX SPLITTING SCHEME FOR THE VECTOR-VALUED CAHN–HILLIARD EQUATION

이현근,이준엽,JAEMIN SHIN 한국산업응용수학회 2019 Journal of the Korean Society for Industrial and A Vol.23 No.1

In contrast to the well-developed convex splitting schemes for gradient flows of two-component system, there were few efforts on applying the convex splitting idea to gradient flows of multi-component system, such as the vector-valued Cahn–Hilliard (vCH) equation.In the case of the vCH equation, one need to consider not only the convex splitting idea but also a specific method to manage the partition of unity constraint to design an unconditionally energy stable scheme. In this paper, we propose a constrained Convex Splitting (cCS) scheme for the vCH equation, which is based on a convex splitting of the energy functional for the vCH equation under the constraint. We show analytically that the cCS scheme is mass conserving and unconditionally uniquely solvable. And it satisfies the constraint at the next time level for any time step thus is unconditionally energy stable. Numerical experiments are presented demonstrating the accuracy, energy stability, and efficiency of the proposed cCS scheme.

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.

마이크로 반구 쉘 형상의 화학증착 탄화규소 TRISO 코팅층의 파괴강도 직접평가

이현근,김도경 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.7

CVD-SiC coating has been introduced as a protective layer in TRISO nuclear fuel particle of high temperature gas cooled reactor(HTGR) due to its excellent mechanical stability at high temperature. In order to prevent the failure of the TRISO particles, it isimportant to evaluate the fracture strength of the SiC coating layer. It is needed to develop a new simple characterization techniqueto evaluate the mechanical properties of the coating layer as a pre-irradiation step. In present work, direct strength measurement methodwith the specimen of hemi-spherical shell configuration was suggested. The indentation experiment on a hemisphere shell with a plateindenter was conducted. The fracture strength of the coating layer is related with the critical load for radial cracking of the shell. Thefinite element analysis was used to drive the semi-empirical equation for the strength measurement. The SiC hemispherical shells wereCVD-SiC coating layer was evaluated from the experimentally measured critical load during the indentation on SiC hemisphere shell.Weibull diagram of fracture strength was also constructed. This study suggested a new strength equation and experimental method tomeasure the fracture strength of CVD-SiC coating of TRISO coated fuel particles.

단어의 개념적 구조와 인지 : Hand 의 경우

이현근 한국현대언어학회 1994 언어연구 Vol.10 No.1

Showing how the conceptual structure of the word is reflected in the human cognition is the purpose of this paper. For this I selected the word 'hand'. Then I identified the primary meaning of 'hand' and it's peripheral meanings. I also investigated it's compounds, derivatives, idiomatic expressions and denominal verbs. I suggest three things : First, the primary meaning of a word should be distinguished from the abstract meaning, such as the invariant meaning, the prototype meaning, or the schematic meaning. The former is generally from the original meaning which is, over time, extended, but the latter is from the abstraction of the uses of a word. The primary meaning is suitable for the conceptual study of word meaning. Second, the conceptual study of the word structure is the most efficient method for the explanation concerning the word meaning extension and the word's compounds and derivatives. Third, metaphoric expressions have an important role in making and understanding compounds and idiomatic expressions of a word.

영어와 한국어 꽃 이름 합성어의 형태론적 및 개념적․의미적 양상

이현근 미래영어영문학회 2012 영어영문학 Vol.17 No.2

In this paper, I aim to compare the morphological and conceptual (semantic) differences between English and Korean flower name compounds. We can conclude three things. First, a lot of Korean compounds include kkot(-꽃) and hwa(-화) and they are in some way systematic. On the contrary, the English compounds have not shown any systematic order morphologically. Second, when we compare the 국화(chrysanthemum)-included compounds and the rose-included compounds, several lexical items are systematized as one category in one language, but not in the other language. Finally, conceptualization differences are shown in many cases such as morning glory vs. 나팔꽃(horn flower), Easter flower vs. 할미꽃(grandmother flower). When we form a compound noun, the salient part of the object is usually conceptualized by language users, but the focus, which has been lexicalized, is different between two languages. That is, conceptualization and lexicalization of the same object may differ in two language systems.

화학증착법에 의하여 제조된 탄화규소 코팅층의 기계적 특성

이현근,김종호,김도경,Lee, Hyeon-Keun,Kim, Jong-Ho,Kim, Do-Kyung 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.8

SiC coating has been introduced as protective layer in TRISO nuclear fuel particle of High Temperature Gas cooled Reactor (HTGR) due to excellent mechanical stability at high temperature. In order to inhibit the failure of the TRISO particles, it is important to evaluate the fracture strength of the SiC coating layer. ]n present work, thin silicon carbide coating was fabricated using chemical vapor deposition process with different microstructures and thicknesses. Processing condition and surface status of substrate.affect on the microstructure of SiC coating layer. Sphere indentation method on trilayer configuration was conducted to measure the fracture strength of the SiC film. The fracture strength of SiC film with different microstructure and thickness were characterized by trilayer strength measurement method nanoindentation technique was also used to characterize the elastic modulus and th ε hardness of the SiC film. Relationships between microstructure and mechanical properties of CVD SiC thin film were discussed.

영어 특이 품사 합성어와 한국어 대응형 연구

이현근 미래영어영문학회 2010 영어영문학 Vol.15 No.2

This paper compares the English compounds, which are the hyphenated compounds with rarely using parts of speech, and their Korean counterparts. Firstly, we find that almost every parts of speech is used for making English compounds, including auxiliary, pronoun, proper noun, determiner, numeral, interrogative, etc. Secondly, there exist semantic/ conceptual differences between English compounds and their Korean counterparts. These different conceptualization processes demonstrate the language-specific aspect.