• 대한수학교육학회지:수학교육학연구
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• 제9권1호
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• pp.81-109
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• 1999

This study aims to reflect the basic principles and teaching-teaming principles of Realistic Mathematics Education in order to suppose an way in which mathematics as an activity is carried out in primary school. The development of what is known as RME started almost thirty years ago. It is founded by Freudenthal and his colleagues at the former IOWO. Freudenthal stressed the idea of matheamatics as a human activity. According to him, the key principles of RME are as follows: guided reinvention and progressive mathematisation, level theory, and didactical phenomenology. This means that children have guided opportunities to reinvent mathematics by doing it and so the focal point should not be on mathematics as a closed system but on the process of mathematisation. There are different levels in learning process. One should let children make the transition from one level to the next level in the progress of mathematisation in realistic contexts. Here, contexts means that domain of reality, which in some particular learning process is disclosed to the learner in order to be mathematised. And the word of 'realistic' is related not just with the real world, but is related to the emphasis that RME puts on offering the students problem situations which they can imagine. Under the background of these principles, RME supposes the following five instruction principles: phenomenological exploration, bridging by vertical instruments, pupils' own constructions and productions, interactivity, and interwining of learning strands. In order to reflect how to realize these principles in practice, the teaming process of algorithms is illustrated. In this process, children follow a learning route that takes its inspiration from the history of mathematics or from their own informal knowledge and strategies. Considering long division, the first levee is associated with real-life activities such as sharing sweets among children. Here, children use their own strategies to solve context problems. The second level is entered when the same sweet problems is presented and a model of the situation is created. Then it is focused on finding shortcomings. Finally, the schema of division becomes a subject of investigation. Comparing realistic mathematics education with constructivistic mathematics education, there interaction, reflective thinking, conflict situation are many similarities but there are alsodifferences. They share the characteristics such as mathematics as a human activity, active learner, etc. But in RME, it is focused on the delicate balance between the spontaneity of children and the authority of teachers, and the development of long-term loaming process which is structured but flexible. In this respect two forms of mathematics education are different. Here, we learn how to develop mathematics curriculum that respects the theory of children on reality and at the same time the theory of mathematics experts. In order to connect the informal mathematics of children and formal mathematics, we need more teachers as researchers and more researchers as observers who try to find the mathematical informal notions of children and anticipate routes of children's learning through thought-experiment continuously.

• 디자인학연구
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• 제13권3호
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• pp.221-234
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• 2000

본 연구는 1970년대 이후 포스트 모더니즘 예술가들의 작품공간에서 나타나고 있는 해체적 방식의 공간개념 고찰을 목적으로 하고 있다. 이에 따라 예술가들의 세계관 변화에 따른 20세기 후기 시대 포스트모더니즘 시각예술 작품에 나타난 복잡계(complex System)의 특성들을 20세기 전기 시대 모더니즘 시각예술 작품에 나타난 단순계(simple System)의 특성들과 비교하여, 그 특성들이 작품형식의 특징을 이루어 주는 구성체계와 어떤 상관관계를 맺으며 조형적 체계화의 변수를 갖게 되는가에 대한 탐구이다. 따라서 그 구성체계들과 변수에 대한 이론적 접근방법으로서는 예술작업에서 기본적 형태 구성 방법으로 사용되는 질서체계의 의미 즉, 모듈(module) 개념을 르 꼬르뷔제(Le Corbusier)의 이론을 통하여 살펴보고, 예술작업에서의 형태구조를 랭거(Suzanne langer)의 형태론 연구에서 정의된 '생명체의 법칙(the law of living form) 즉, '유기체의 원리(the principles of organization)'로 볼 수 있을 때, 인체나 자연 생태계의 성장구조에서 나타나는 유기체적 구조라고 보며, 모듈의 법칙을 지배하는 원리를 햄비지(Jay Hambidge)가 주장하는 다이내믹 시미트리(dynamic symmetry)로서 작품 공간을 산술분석 하였다. 이로써 20세기 전기 시대와 후기 시대의 시각예술 작품에서 나타난 양식의 특성들을 제시작품을 통하여 그 내용면과 형식면에서 차이를 비교 분석할 수 있었으며 이를 통해 20세기 후기 포스트 모더니즘 시각예술 작품에서 나타나는 복잡계의 특성들이 새로운 조형적 체제화의 변수에 작용하는 원리를 다음과 같이 다음과 같이 제안할 수 있게 되었다. 첫째, 작품공간에서의 모듈은 다이내믹 시미트리로부터 만들어지고 이루어져야 한다. 둘째, 모듈은 다이내믹 시미트리의 필요충분 조건인 만족스럽고(acceptable), 효율적이며(effcient), 융통적이고(flexible), 적응력이 뛰어난(adaptable) 인간적 요구사항을 충족시켜야 한다. 셋째, 다이내믹 시미트리는 역(逆, reciprocity)의 원리와 보상(補賞, complement)의 원리를 제 1의 구성원리로 하며 공간에서 서로에 대한 역과 공통성(common property)을 갖고 자기유사를 지닐 때 연속체(continuum)를 손상하지 않고 전체공간을 유기체적으로 분절한다.

• 대한수학교육학회지:수학교육학연구
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• 제9권1호
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• pp.183-203
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• 1999

In this study, we analysed the constituents of proof and examined into the reasons why the students have trouble in learning the proof, and proposed directions for improving the teaming and teaching of proof. Through the reviews of the related literatures and the analyses of textbooks, the constituents of proof in the level of middle grades in our country are divided into two major categories 'Constituents related to the construction of reasoning' and 'Constituents related to the meaning of proof. 'The former includes the inference rules(simplification, conjunction, modus ponens, and hypothetical syllogism), symbolization, distinguishing between definition and property, use of the appropriate diagrams, application of the basic principles, variety and completeness in checking, reading and using the basic components of geometric figures to prove, translating symbols into literary compositions, disproof using counter example, and proof of equations. The latter includes the inferences, implication, separation of assumption and conclusion, distinguishing implication from equivalence, a theorem has no exceptions, necessity for proof of obvious propositions, and generality of proof. The results from three types of examinations; analysis of the textbooks, interview, writing test, are summarized as following. The hypothetical syllogism that builds the main structure of proofs is not taught in middle grades explicitly, so students have more difficulty in understanding other types of syllogisms than the AAA type of categorical syllogisms. Most of students do not distinguish definition from property well, so they find difficulty in symbolizing, separating assumption from conclusion, or use of the appropriate diagrams. The basic symbols and principles are taught in the first year of the middle school and students use them in proving theorems after about one year. That could be a cause that the students do not allow the exact names of the principles and can not apply correct principles. Textbooks do not describe clearly about counter example, but they contain some problems to solve only by using counter examples. Students have thought that one counter example is sufficient to disprove a false proposition, but in fact, they do not prefer to use it. Textbooks contain some problems to prove equations, A=B. Proving those equations, however, students do not perceive that writing equation A=B, the conclusion of the proof, in the first line and deforming the both sides of it are incorrect. Furthermore, students prefer it to developing A to B. Most of constituents related to the meaning of proof are mentioned very simply or never in textbooks, so many students do not know them. Especially, they accept the result of experiments or measurements as proof and prefer them to logical proof stated in textbooks.

• 서비스연구
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• 제5권2호
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• pp.71-81
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• 2015

RSA 공개키 암호화 알고리즘에서는 소수, 키 생성, 소인수분해, 오일러 함수, 키 셋업, 합동식과 법, 지수 처리가 응용된다. 이와같은 알고리즘의 토대는 수학원리이다. 수학원리 중에서 첫 번째 개념은 소수를 구하여 응용하는 방법에서 출발한다. 두 개의 매우 큰 소수의 곱을 구하는 것은 용이 하지만 그 곱에서 원래의 두 개의 소수를 역 추적하는 것은 매우 어렵다는 원리를 이용한다. p와 q를 매우 큰 소수라 하면 이 두 개의 곱 $n=p{\times}q$를 구하는 것은 쉽지만 역으로, 합성수인 n에서 p와 q를 추적하는 방법은 거의 불가능하다. RSA 암호화 알고리즘에서는 수학적으로 역함수 계산이 어려운 일방향 함수를 구현하기 위해 자리수가 많은 양의 정수의 소인수 분해 문제를 사용하고 있다. 역 방향으로의 계산을 어렵게 하기 위해 mod의 개념을 소인수 분해 문제에 더해서 사용한다. 암호화에 대한 관심분야는 대개 알고리즘 구현과 사용에 집중되고 있지만 막상 암호 알고리즘을 처음 도입하는 경우에는 어떤 프로세스를 거쳐야 현장 업무에 적용되는지를 알 수 없다. 본 연구는 공개키 알고리즘 속성 진단을 기반으로 한 현장 업무 암호화 적용 프로세스 방안을 제시한다.

• 건축역사연구
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• 제8권3호
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• pp.53-64
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• 1999

The subjects of the research is the architecture expressed traditionality from the time of the Open Port on, including North Korea region. The scope is divided into three periods; the first is from the Open Port to the Rehabilitation (光復),1945, the second is from then to 1960, and the last is from 1960 to the present. The expression of Koreanity(韓國性) should be concerned with the states at the time. In the beginning of the first period the alienate culture and the new modern facilities, like electricity, telecommunication system, train service, etc., rushes to Korea and the traditional architecture accepted the most of the new-comings; therefore, the original form was transformed. That seems to be the beginning of the discourse on traditionality in Korea architecture. The expression was showed up in four parts: ${\bullet}$ Korea traditional architecture accepting the foreign culture and the modern facilities ${\bullet}$ the compromise between foreign and traditional architectural form ${\bullet}$ the compromise between the Modem and traditional architecture ${\bullet}$ the Imperial Crown Style(帝冠樣式) which is the eclectic architecture with transformed roof. The figurative expression in the present architecture was showed up in roughly two parts: ${\bullet}$ the traditional form directly depicted wholly / partially ${\bullet}$ the abstract traditional form wholly / partially Moreover the results on the research traditional architecture have been collected, the principles have been drawn out. Especially the first beauty is not on form or figure of a building but on the composition of architectures and the harmony of the natural circumstances and architectures. So many contemporary architects make efforts to apply the principles to the composition and formation of current architecture.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.425.1-425.1
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• 2014

Thermal transport in nanomaterials is not only scientifically interesting but also technological important for various future electronic, bio, and energy device applications. Among the various computation approaches to investigate lattice thermal transport phenomena in nanoscale, the atomistic nonequilibrium Green's function approach based on first-principles density functional theory calculations appeared as a promising method given the continued miniaturization of devices and the difficulty of developing classical force constants for novel nanoscale interfaces. Among the nanometerials, carbon atomic chains, namely the cumulene (all-doulble bonds, ${\cdots}C=C=C=C{\cdots}$) and polyyne (alternation of single and triple bonds, ${\cdots}C{\equiv}C-C{\equiv}C{\cdots}$) can be considered as the extream cases of interconnction materials for nanodevices. After the discovery and realization of carbon atomic chains, their electronic transport properties have been widely studied. For the thermal transport properties, however, there have been few literatures for this simple linear chain system. In this work, we first report on the development of a non-equilibrium Green's function theory-based computational tool for atomistic thermal transport calculations of nanojunctions. Using the developed tool, we investigated phonon dispersion and transmission properties of polyethylene (${\cdots}CH2-CH2-CH2-CH2{\cdots}$) and polyene (${\cdots}CH-CH-CH-CH{\cdots}$) structures as well as the cumulene and polyyne. The resulting phonon dispersion from polyethylene and polyene showed agreement with previous results. Compared to the cumulene, the gap was found near the ${\Gamma}$ point of the phonon dispersion of polyyne as the prediction of Peierls distortion, and this feature was reflected in the phonon transmission of polyyne. We also investigated the range of interatomic force interactions with increase in the size of the simulation system to check the convergence criteria. Compared to polyethylene and polyene, polyyne and cumulene showed spatially long-ranged force interactions. This is reflected on the differences in phonon transport caused by the delicate differences in electronic structure.

• 한국실내디자인학회논문집
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• 제15권4호
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• pp.106-114
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• 2006

The purposes of natural science museums are to educate the general public on the principles and application of science, and help them understand various aspects of science technology. Data should be analyzed by considering these educational aspects of exhibition, and the methods of presenting exhibits should be decided. Accordingly, the composition of exhibition contents with various exhibition elements has an important role at natural science museums. The relation and structure of exhibition themes are significant factors in helping visitors understand the principles of science and a system of viewing circulation can be used as an important tool for understanding the flow of exhibition. In other words, at the planning stage for the composition of exhibition contents, the relation of exhibition themes as well as the circulation patterns of viewers can induce active viewing behaviors. Therefore, centering on the patterns of viewing circulation as well as on the connectivity of exhibition themes at natural science museums, the purposes of this research are: 1) to conceptualize the composition of exhibition contents; and 2) to find elements that can induce active viewing behaviors by analyzing visitors' viewing behaviors. This research was establishing an analytical indicator of contact for viewing behaviors observed from the composition of exhibition scenarios, the active viewing patterns of engagement, first contact, and repeated contact were analyzed. First, a composition pattern with a high participation rate, in contact with exhibits, was found to induce an overall-viewing circulation and have a big ring of the composition of exhibition themes. Second, by inducing a partial-viewing circulation pattern, a high rate of first contacts was observed from a ring pattern of theme connection. Even for the structure with theme connection with depth, a high frequency of contacts with various exhibits was found when exhibition themes have a ring pattern. Third, the repeated contacts were mostly found in the form of scenarios, which has a successive structure of ring and cross patterns.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2556-2566
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• 2023

A first-principle approach within the framework of density functional theory was employed to study the effect of vacancy defects and fission products (FPs) doping on the mechanical, electronic, and thermodynamic properties of uranium monocarbide (UC). Firstly, the calculated vacancy formation energies confirm that the C vacancy is more stable than the U vacancy. The solution energies indicate that FPs prefer to occupying in U site rather than in C site. Zr, Mo, Th, and Pu atoms tend to directly replace U atom and dissolve into the UC lattice. Besides, the results of the mechanical properties show that U vacancy reduces the compressive and deformation resistance of UC while C vacancy has little effect. The doping of all FPs except He has a repairing effect on the mechanical properties of U_1-xC. In addition, significant modifications are observed in the phonon dispersion curves and partial phonon density of states (PhDOS) of UC_1-x, Zr_xU_1-xC, Mo_xU_1-xC, and Rh_xU_1-xC, including narrow frequency gaps and overlapping phonon modes, which increase the phonon scattering and lead to deterioration of thermal expansion coefficient (α_V) and heat capacity (C_p) of UC predicted by the quasi harmonic approximation (QHA) method.

• 한국표면공학회지
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• 제42권1호
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• pp.8-12
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• 2009

Electronic structures and chemical bonding of Li-intercalated $LiTiS_2$ and $LiTiO_2$ were investigated by using discrete variational $X{\alpha}$ method as a first-principles molecular-orbital method. ${\alpha}-NaFeO_2$ structure is the equilibrium structure for $LiCoO_2$, which is widely used as a commercial cathode material for lithium secondary battery. The study especially focused on the charge state of Li ions and the magnitude of covalency around Li ions. The average voltage of lithium intercalation was calculated using pseudopotential method and the average intercalation voltage of $LiTiO_2$ was higher than that of $LiTiS_2$. It can be explained by the differences in Mulliken charge of lithium and the bond overlap population between the intercalated Li ions and anions in $LiTiO_2$ as well as $LiTiS_2$. The Mulliken charge, which means the ionicity of Li atom, was approximately 0.12 in $LiTiS_2$ and the bond overlap population (BOP) indicating the covalency between Ti and S was about 0.339. One the other hands, the Mulliken charge of lithium was about 0.79, which means that Li is fully ionized. The BOP, the covalency between Ti and O, was 0.181 in $LiTiO_2$. Because of high ionicity of Li and the weak covalency between Ti and the nearest anion, $LiTiO_2$ has a higher intercalation voltage than that of $LiTiS_2$.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.1029-1036
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• 2024

Drawing on the deep experience and understanding of the principles of nuclear safety, as well as many years of nuclear power plant design and operation, the EDF led NUWARD SMR Project is developing a design for a Small Modular Reactor (SMR) of 340 MWe composed of two 170 MWe independent units, that will supplement the offering of high-output nuclear reactors, especially in response to specific needs such as replacement of fossil-fuelled power plants. NUWARD SMR is a mix of proven and innovative design features that will make it more commercially competitive, while integrating safety features that comply with the highest international standards. Following the principles of redundancy and diversity and rigorous application of Defence in Depth (DID), with an international view on nuclear safety licensing, the Project also incorporates new safety approaches into its design development. The NUWARD SMR Project has been in development for a number of years, it entered conceptual design formally in mid-2019 and entered Basic Design in 2023. The objective of the concept design phase was to confirm the project technological choices and to define the first design configuration of the NUWARD SMR product, to document it, in order to launch pre-licensing with the French Safety Authority (ASN) and to define its estimated cost and its subsequent development and construction schedules. As a delivery milestone the Safety Options file (called the Dossier d'Options de Sûreté (DOS)) has been submitted to ASN in July 2023 for their opinion. An integral part of the NUWARD SMR Project, is not only to deliver a design suitable for France and to satisfy French regulation, but to develop a product suitable and indeed desirable, for the international market, with a first focus in Europe. In order to achieve its objectives and realise its market potential, the NUWARD SMR Project needs to define and realise its safety approach within an international environment and that is the key subject of this paper. The following paper: • Summarises the foundation principles and technological background which underpin the design; • Contextualises the key design features with regard to the international safety regulatory framework with particular emphasis on innovative passive safety aspects; • Illustrates the Project activities in preparation for first licensing in France, and also a wider international view via the ASN led Joint Early Review of the NUWARD SMR design, including Finnish and Czech Republic regulators, recently joined by the Swedish, Polish and Dutch regulators; • Articulates the collaborative approach to design development from involvement with the Project partners (the Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Naval Group, TechnicAtome, Framatome and Tractebel) to the establishment of the International NUWARD Advisory Board (INAB), to gain greater international insight and advice; • Concludes with the focus on next steps into detailed design development, standardisation of the design and its simplification to enhance its commercial competitiveness in a context of further harmonisation of the nuclear safety and licensing requirements and aspirations.