• 대한수학회지
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• 제54권2호
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• pp.507-516
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• 2017

Real Bott manifolds is a class of flat manifolds with holonomy group $\mathbb{Z}^k_2$ of diagonal type. In this paper we formulate necessary and sufficient conditions of the existence of a Spin-structure on real Bott manifolds. It extends results of [9].

• 한국산학기술학회논문지
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• 제15권8호
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• pp.5280-5287
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• 2014

본 논문에서는 라만스펙트럼의 효과적인 판별을 위해 계층 트리 구조로 클래스를 그룹화 하는 방식을 제안하였다. 실험데이터로는 28종 화학물질의 라만 스펙트럼을 준비하였고 잡음제거, 정규화 등의 전처리 수행하였다. 다음으로 사전실험을 통해 서로 간에 분류오류를 발생시키는 물질들을 그룹화 하여 계층 구조의 클래스를 구성하였고, 각각의 상위, 하위 클래스에 PCA(principal component analysis) 특징추출과 MAP(maximum a posteriori probability) 방식의 분류실험을 수행하였다. 실험 결과에 의하면 계층 구조의 클래스를 적용한 경우 평균 2.7개의 특징을 사용하여 분류가 100% 이루어짐을 확인할 수 있었다. 계층 구조를 적용하지 않는 기존의 방식에서 6개의 특징을 사용할 때 동일한 분류결과를 보였음을 감안해 보면, 제안한 방식이 전체 계산 복잡도의 측면에서 훨씬 뛰어남을 알 수 있다. 따라서 제안한 방식이 실제 응용에 보다 적합하다고 할 수 있다.

• 융합신호처리학회논문지
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• 제4권1호
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• pp.41-48
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• 2003

본 논문에서는 DGS(Defected Ground Structure)에 대한 새로운 등가 회로를 제안하였으며, 이를 IMT-2000용 AB급 대전력 증폭기 설계에 적용하여 증폭기의 성능을 향상시켰다. 새로운 DGS 등가 회로는 병렬의 LC 공진기와 병렬 형태의 캐패시턴스로 구성되어 금속 접지면에 에칭된 결함으로 인한 프린징(fringing) 효과를 반영하도록 하였으며, 전력 증폭기 출 단 정합 회로를 최적화하기 위하여 사용되었다. 이전의 논문에서도 하모닉 성분의 억제와 증폭기의 효율 개선을 위하여 DGS를 사용하였으나 DGS 등가 회로의 해석은 없었으며(1), 본 논문에서는 이를 개선하여 회로 시뮬레이션을 통한 정한 DGS의 등가 회로를 AB급 증폭기의 출력 단 정합회로에 적용함으로써 성능 향상과 함께 증폭기 제작 후에 튜닝이 거의 필요없는 정확한 설계 방법을 제시하였다. 이와 같이 제안된 전력 증폭기의 설계 방법은 정확한 설계 결과를 제공함으로써 최적 부하 조건과 하모닉 성분의 제거 성능을 동시에 만족시킬 수 있었다. 제안된 방법의 효과를 입증하기 위하여 DGS를 적용한 기존의 방법과 새로이 제안된 방법을 사용하여 20W급의 전력 증폭기를 설계 및 제작하였으며, 그 측정 결과를 비교하였다.

• 한국문헌정보학회지
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• 제41권4호
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• pp.49-68
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• 2007

이 연구에서는 우리나라 공공 도서관에서 적극적으로 수용해야할 정보취약계층에 대한 정보서비스 확산을 위해 필요한 개념과 기본적인 정보서비스 전략을 제안하였다. 공공도서관은 정보취약계층을 크게 장애인과 생활보호대상자, 노인 등으로 구분하여 각 계층의 특성을 고려한 정보서비스를 제공하여야 한다. 이들을 위한 정보서비스는 시설적 배려와 제도적 배려, 기기적 배려로 구분할 수 있다. 시설적 배려는 Information Commons 전략에 따라 정보화 기기와 시설이 통합된 공간에서 참고사서에 의해 협업하는 공간의 배치를 고려한다. 제도적 배려는 도서관에서 이용자 교육과 외부 전문가와의 협업교육을 수행하고, 정보취약계층별에 따른 개인화된 서비스를 제공해야 한다. 기기적 배려는 장애인을 위해 개발된 기기수준과 같이 다른 정보취약계층의 특성을 고려해야 한다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권3호
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• pp.367-375
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• 2018

The present paper considers the contact between energy-saving device of ice-class vessel and ice block. The main objective of this study is to clarify the tendency of the ice impact force and the structural response as well as interaction effects of them. The contact analysis is performed by using LS-DYNA finite element code. The main collision scenario is based on Finnish-Swedish ice class rules and a stern duct model is used as an energy-saving device. For the contact force, two modelling approaches are adopted. One is dynamic indentation model of ice block based on the pressure-area curve. The other is numerical material modelling by LS-DYNA. The authors investigated the sensitivity of the structural response against the ice contact pressure, the interaction effect between structure and ice block, and the influence of eccentric collision. The results of these simulations are presented and discussed with respect to structural safety.

• 한국언어정보학회:학술대회논문집
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• 한국언어정보학회 2007년도 정기학술대회
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• pp.67-75
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• 2007

This paper presents the architectural aspects of the phrase analyzer that attempts to recognize phrases and identify the functional roles in the sentences in formal Japanese documents. Since the object of interest is a phrase, the current system, designed in an object-oriented architecture, contains the Phrase class, and makes use of the linguistic generalization about languages with Case markers that a phrase, whether a noun phrase, a verb phrase, a postposition (or preposition) phrase or a clause phrase, can be separated into the content and the function components. Without a dictionary, and drawing on the orthographic information on the words to parse, it also contains a class that identifies the types of characters, a class representing grammar, and a class playing the role of a controller. The system has a simple and intuitive structure, externally and internally, and therefore is easy to modify and extend.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.161-165
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• 2011

In this paper, a high-efficiency DC-AC converter is used for wireless energy transmission. The DC-AC convertter is implemented by combining the oscillator and power amplifier. Given that the conversion efficiency of a DC-AC converter is strongly affected by the efficiency of the power amplifier, a high-efficiency power amplifier is implemented using a class-E amplifier structure. Also, because of the low output power of the oscillator connected to the input stage of the power amplifier, a high-gain two-stage power amplifier using a drive amplifier is used to realize a high-output power DC-AC converter. The high-efficiency DC-AC converter is realized by connecting the oscillator to the input stage of the high-gain high-efficiency two-stage class-E power amplifier. The output power and the conversion efficiency of the DC-AC converter are 40.83 dBm and 87.32 %, respectively, at an operation frequency of 13.56 MHz.

• 대한원격탐사학회지
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• 제21권5호
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• pp.417-423
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• 2005

A fuzzy approach using an EM algorithm for image classification is presented. In this study, a double compound stochastic image process is assumed to combine a discrete-valued field for region-class processes and a continuous random field for observed intensity processes. The Markov random field is employed to characterize the geophysical connectedness of a digital image structure. The fuzzy classification is an EM iterative approach based on mixture probability distribution. Under the assumption of the double compound process, given an initial class map, this approach iteratively computes the fuzzy membership vectors in the E-step and the estimates of class-related parameters in the M-step. In the experiments with remotely sensed data, the MRF-based method yielded a spatially smooth class-map with more distinctive configuration of the classes than the non-MRF approach.

• 인문언어
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• 제2권2호
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• pp.203-221
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• 2002

The ideal of middle class British masculinity and the representative of the new Victorian respectability, the ″gentleman″ was difficult to define amidst the class mobility and social change of the nineteenth century. Was the gentleman to be identified by class and by money\ulcorner By behavior and clothing\ulcorner By religion and morality\ulcorner This essay focuses on the problem of the ″gentleman″ as it was debated in the Victorian era and as it was reflected in the biography and work of the mid-nineteenth century's most important English writer, Charles Dickens. I examine the critical debate surrounding the Victorian idea of the ″gentleman″ by comparing the arguments of Shirley Robin Letwin's The Gentleman in Trollope(1982) and Robin Gilmour's The Idea of the Gentleman in the Victorian Novel(1981). Letwin views the ″gentleman″ as largely transcending class structure, while Gilmour's more historically-conscious view locates the gentleman as emerging out of, and even enabling, the class negotiations of this period. Against the backdrop of such debates, I discuss Charles Dickens's struggles with the idea of the gentleman in theory and in practice. In his novels, especially his semi-autobiographical bildungsromane about the growth and development of boys into adulthood, Dickens prominently engages with the identity and definition of the gentleman. As I demonstrate in this essay, this interest originated from Dickens's own childhood trauma and his subsequent drive to attain gentility, a necessity complicated by the vicissitudes of his personal and professional life.

• 대한수학회논문집
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• 제32권2호
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• pp.233-260
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• 2017

Let R be a factorial domain. In this work we investigate the connections between the arithmetic of Int(R) (i.e., the ring of integer-valued polynomials over R) and its monadic submonoids (i.e., monoids of the form {$g{\in}Int(R){\mid}g{\mid}_{Int(R)}f^k$ for some $k{\in}{\mathbb{N}}_0$} for some nonzero $f{\in}Int(R)$). Since every monadic submonoid of Int(R) is a Krull monoid it is possible to describe the arithmetic of these monoids in terms of their divisor-class group. We give an explicit description of these divisor-class groups in several situations and provide a few techniques that can be used to determine them. As an application we show that there are strong connections between Int(R) and its monadic submonoids. If $R={\mathbb{Z}}$ or more generally if R has sufficiently many "nice" atoms, then we prove that the infinitude of the elasticity and the tame degree of Int(R) can be explained by using the structure of monadic submonoids of Int(R).