• Nuclear Engineering and Technology
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• v.41 no.5
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• pp.747-752
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• 2009

A vulnerability assessment is essential for the efficient operation of a physical protection system (PPS). Previous assessment codes have used a simple model called an adversary sequence diagram. In this study, the use of a two-dimensional (2D) map of a facility as a model for a PPS is suggested as an alternative approach. The analysis of a 2D model, however, consumes a lot of time. Accordingly, a generalized heuristic algorithm has been applied to address this issue. The proposed assessment method was implemented to a computer code; Systematic Analysis of physical Protection Effectiveness (SAPE). This code was applied to a variety of facilities and evaluated for feasibility by applying it to various facilities. To help upgrade a PPS, a sensitivity analysis of all protection elements along a chosen path is proposed. SAPE will help to accurately and intuitively assess a PPS.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.73.1-73.1
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• 2015

Isolated galaxies in low-density regions are significant in the sense that they are least affected by the hierarchical pattern of galaxy growth and interactions with perturbers at least for the last few Gyr. To form a comprehensive picture of the star formation history of isolated galaxies, we construct a catalog of isolated galaxies and their comparison sample in relatively denser environments. The galaxies are drawn from SDSS DR7 in the redshift range of 0.025 < z < 0.044. We performed visual inspection and classified their morphology following the Hubble classification scheme. We have investigated the color-magnitude diagram and found elliptical and unbarred spiral galaxies in isolated systems are relatively fainter and bluer than those in denser regions. For the spectroscopic study, we make use of the OSSY catalog (Oh et al. 2011). Our analysis on the absorption-line properties based on the comparison with stellar population models suggests that isolated elliptical galaxies are likely to be younger and metal poorer, while isolated Sc-type galaxies seem to have older luminosity-weighted ages, than their high-density counterpart. In addition, according to the BPT diagnostics, early-type galaxies among isolated galaxies are rather evenly classified into star forming, composite, Seyfert and LINER, whereas their comparisons are mainly populated in the LINER region. On the other hand, late-type galaxies do not show any prominent difference. We discuss the evolutionary histories of isolated galaxies in the context of the standard ${\Lambda}CDM$ cosmology.

• Proceedings of the Korea Association of Information Systems Conference
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• 2004.05a
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• pp.269-272
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• 2004

콤포넌트 가변성 장치를 이용하면 사용자가 용도에 알맞게 기능을 특화할 수 있다. 프로덕트 라인은 다양하고 빠르게 변화하는 시장의 요구사항과 특정 도메인 영역에 속하는 애플리케이션간의 재사용 가능한 아키텍처 및 컴포넌트의 구성으로부터 연관된 시스템 구축 시 생산성과 품질의 향상을 제공함으로써 현재 많은 관심의 초점이 되고 있다. 프로덕트 라인에서 컴포넌트 내부에 공통으로 사용할 워크프롤로를 가지고 있어 컴포넌트 사용자는 Sequence Diagram등을 통해 메시지 흐름을 직접 구현할 필요가 없다. 재사용 가능한 아키텍처는 많은 변화 계획들과 메커니즘을 포함하고 있다. 하지만, 아키텍처를 설계하기 위한 아키텍처에서의 변화성 관리에 대한 명확한 방법이 미흡하다. 따라서 본 논문에서는 재사용 가능한 아키텍처를 설계하기 위해 변화성의 명확한 표현과 아키텍처에서의 적절한 위치를 식별하기 위해, 다양한 변화성 타입을 정의하고, 프로덕트 라인 아키텍처상의 컴포넌트 설계의 변화성을 표현하고, 다중 뷰의 모델링을 통하여 프로덕트 라인의 다양한 측면을 제시하고, 사례연구로 성적관리 컴포넌트 모델링에 적용해 보고자 한다.

• Journal of Korean Elementary Science Education
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• v.37 no.2
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• pp.173-187
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• 2018

The purpose of this study is to clarify the specific terms of epistemic and epistemological by reviewing the literature on epistemological understanding of science learning, examine the necessity of epistemic discourse analysis based on the view of social epistemology, and provide an exemplar of practical epistemology analysis for elementary children's science learning. The review was conducted in terms of meaning and terminology about epistemic or epistemological approach to science learning, epistemology of/for science, and methodologies for epistemic discourse analysis. As an alternative way of epistemic discourse analysis in science classroom I employed practical epistemology analysis (by Wickman), evidence-explanation continuum (by Duschl), and DREEC diagram (by Maeng et al.). The methods were administered to an elementary science class for the third grade where children observed sedimentary rocks. Through the outcomes of analysis I sought to understand the processes how children collected data by observation, identified evidence, and constructed explanations about rocks. During the process of practical epistemology analysis the cases of four categories, such as encounter, stand-fast, gap, and relation, were identified. The sequence of encounter, stand fast, gap, and relation showed how children observed sedimentary rocks and how they came to learn the difference among the rocks. The epistemic features of children's observation discourse, although different from scientists' discourses during their own practices, showed data-only conversation, evidence-driven conversation, or explanation inducing conversation. Thus I argue even elementary children are able to construct their own knowledge and their epistemic practices are productive.

• Communications of Mathematical Education
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• v.28 no.2
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• pp.219-234
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• 2014

Music and mathematics have a lot of structural similarities. Major and minor triads used importantly in music are in a relationship of inversion in which the sequence of the intervals is reversed, which is equivalent to reflection in mathematics. Geometrical expressions help understand structures in music as well as mathematics, and a diagram that shows tonal relationships in music is called Tonnetz. Relationships of reflection between major and minor triads can easily be understood by using Tonnetz, and also, transpositions can be expressed in translation. This study looks into existing Tonnetz and introduces S-Tonnetz newly formed by a mathematical principle.

• IE interfaces
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• v.16 no.4
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• pp.450-462
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• 2003

In this paper, we deal with a process and layout design for producing a planned amount of Sikhye in a given limited time period under a reasonable production schedule. We represent a Sikhye production line as a vector N, the element of which denotes the number of tanks required in each process and our objective is to find an appropriate vector which minimizes the total investment cost. We suggest a systematic method for finding an appropriate N and an appropriate layout to N. In detail, first, we decide the required sequence of processes and the required operations for each process and we estimate standard operating times. Second, constructing a precedence diagram, we find a critical path in order to reduce the total production lead time for a batch of Sikhye. Third, given a limited N space, we manage to construct manually each production schedule using both the processing times of the critical operations and transfer times. Finally, we find an optimal vector N which gives a minimum investment cost and meets both the time constraint and quantity constraint. In addition, with the estimated relative size of each tank, we suggest an appropriate conceptual layout design including an expansion area for future demands, based on the span technique used in the field of architectural design.

• Structural Engineering and Mechanics
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• v.32 no.4
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• pp.501-516
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• 2009

This paper aims to study the large deflections of variable-arc-length elastica subjected to the terminal forces (e.g., axial force and torque). Based on Kirchhoff's rod theory and with help of Euler parameters, the set of nonlinear governing differential equations which free from the effect of singularity are established together with boundary conditions. The system of nonlinear differential equations is solved by using the shooting method with high accuracy integrator, seventh-eighth order Runge-Kutta with adaptive step-size scheme. The error norm of end conditions is minimized within the prescribed tolerance ($10^{-5}$). The behavior of VAL elastica is studied by two processes. One is obtained by applying slackening first. After that keeping the slackening as a constant and then the twist angle is varied in subsequent order. The other process is performed by reversing the sequence of loading in the first process. The results are interpreted by observing the load-deflection diagram and the stability properties are predicted via fold rule. From the results, there are many interesting aspects such as snap-through phenomenon, secondary bifurcation point, loop formation, equilibrium configurations and effect of variable-arc-length to behavior of elastica.

• Journal of Power Electronics
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• v.12 no.4
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• pp.548-558
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• 2012

In this paper, a novel offset-based single-state pulse width modulation (PWM) method for achieving zero common-mode voltage (CMV) and reducing switching losses in multilevel inverters is presented. The specific active switching state of the zero common-mode (ZCM) voltage that approximates the reference voltage can be deduced from the switching state sequence of the reduced CMV phase disposition PWM (CMV PD PWM) method. From the reference leg voltages for the zero common-mode voltage, an N-to-2-level transformation defines a virtual two-level inverter and the corresponding nominal leg voltage references. The commutation process of the reduced CMV PD PWM method in a multilevel inverter and its outputs can be simply followed in a nominal switching time diagram for the virtual inverter. The characteristics of the reduced CMV PD PWM and the single-state PWM for zero common-mode voltage are analyzed in detail in this paper. The theoretical analysis of the proposed PWM method is verified by experimental results.

• Journal of Korean Elementary Science Education
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• v.23 no.3
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• pp.199-207
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• 2004

Elementary science curriculum is designed to be closely-related magnetism with electricity in a physics domain and this paper explored whether elementary school students have recognized of relationships between them and whether there are any trends in the degree of recognition by grades. The elementary students of 3rd to 6th grade (total 154 persons) in a school in a local city participated in the experiment. Two forms of questionnaire were administrated to each grades. In the first questionnaire about magnetism, students were asked to rank the physics terms as the degree of proximity into magnetism and to write briefly the reason. In the second questionnaire about electricity, students were asked to do the same routine. The closer to the central term in the diagram, the lower score were given and the terms were classified as closely related to magnetism, electricity and the rest. Calculated the response frequency and averaged by the ranked terms, it was examined that the scores of proximity in how students closely rated conception to magnetism and electricity. The result said that the upper grades students showed the degree of proximity with magnetism and electricity as closely. Therefore, the sequence of comprehension of magnetism and electricity concept, which was found in the elementary school curriculum, seems to be found in the elementary students＇ recognitions by grades.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.171-176
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• 2001

This paper describes the methodology of an IEC 1131-3-based control logic generator for the control system design and converting algorithm between programmable languages. The proposed control logic generator is generated based on the software model and common element with data type, variables, POUs(program organization unit) and execution control unit commonly used within programmable languages of IEC 1131-3 Standard. The generation method of object file was proposed on five programmable language based on IECI 131-3. The generation method of object file is represented as following; 1) the generation method using conversion algorithm from LD to IL with FBD(function block diagram), 2) the generation method using C code generation algorithm from SFC using the SFC execution sequence with FBD and ST(structured text). The proposed control logic generator was implemented by Visual C++ and MFC on MS-windows NT 4.0