• Journal of Sensor Science and Technology
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• v.10 no.2
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• pp.91-100
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• 2001

A $8{\times}8$ foveated (log-polar) retina chip for edge detection has been designed and fabricated using CMOS technology. Retina chip performs photo-input sensing, edge extraction and motion detection and we focused edge extraction. The pixel distribution follows the log-polar transform having more resolution in the center than in the periphery and can reduce image information selectively. This kind of structure has been already employed in simple image sensors for normal cameras, but never in edge detection retina chip. A scaling mechanism is needed due to the different pixel size from circumference to circumference. A mechanism for current scaling in this research is channel width scaling of MOS transistor. The designed chip has been fabricated using standard $1.5{\mu}m$ single-poly double-metal CMOS technology.

• Journal of Educational Research in Mathematics
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• v.14 no.1
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• pp.129-142
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• 2004

These days, constructivism has become a central theory in mathematics education. A essential concept in constructivism is 'construction' and the meaning of construction of mathematical knowledge is a core issue in mathematics educational field. In the basis of Dewey's epistemology, this article is trying to explicate the meaning of construction of mathematical knowledge. Dewey, Kant and Piaget coincide in construction of knowledge from the viewpoint of the interaction between mind and environment. However, unlike Dewey's concept, Kant and Piaget are still in the line of traditional realistic epistemology. Dewey's concept of construction logically implies teaching-learn learning principles. This can be named as a principle of genetic construction and a principle of progressive consciousness.

• School Mathematics
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• v.9 no.1
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• pp.65-97
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• 2007

Problem solving and mathematical applications have been increasingly emphasized in school mathematics over the past ten years. Recently it is recommended that mathematical applications and modeling situations be incorporated into the secondary school curriculum. Many researches on this approach have been conducted in Korea. But unfortunately two thirds of these researches have been studied by graduate students. Therefore, more professional researchers should be concerned with the study related to mathematical modelling activity. This study is planning to investigate and establish i) the concepts and meanings of mathematical model, mathematical modelling, and mathematical modelling process, ii) the properties of problem situations introduced and dealt with in mathematical modelling activity, and iii) relationship between mathematical modelling activity and problem solving activity, and so on. To accomplish this, this study is based on the analysis and comparison of 11 articles published in domestic journals and 22 domestic master papers.

• Journal of Internet Computing and Services
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• v.18 no.5
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• pp.95-102
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• 2017

With the development and popularization of Internet, the competition of SNS market is now getting fiercer and fiercer. SNS service providers need to keep updating their service to sustain their customers' continuance use. However, due to the homogenization of functions and services from different applications provided by different developers, there comes a new phenomenon that users shift from one SNS to another SNS. In line with this, the current study aims to explore factors affecting switching intention among SNS users by applying migration theory which explains people's migration behavior from one place to another. Findings from surveys of Korean and Chinese college students suggest that there was a difference of factors influencing switching intention among the two countries. For Korean college students, alternative attraction was the strongest factor leading to SNS switching intention. On the other hand, peer pressure was the strongest factor leading to SNS switching intention among Chinese college students.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.278-283
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• 2010

The cationic polymerization of oxolane high explosives which have pendant explosive groups such as azido, nitrato and hydrazino is investigated theoretically using the semiempirical MINDO/3, MNDO and AM1 methods. The nucleophilicity and basicity of oxolane high explosives can be explained by the negative charge on oxygen atom of oxolane. The reactivity of propagation in the polymerization of oxolane can be represented by the positive charge on carbon atom and the low LUMO energy of active species of oxolane. The reaction of the oxolane high explosives in oxonium ion form to the open chain carbenium ion form is expected by computational stability energy (17.950~30.197 kcal/mol) of the oxonium ion and carbenium ion favoring the carbenium ion. The relative equilibrium concentration of cyclic oxonium ion and carbenium ion is found to be a major determinant of mechanism, owing to the rapid equilibrium of these catoinic forms. Based on calculation, in the prepolymer propagation step, $S_N1$ mechanism will be at least as fast as that for $S_N2$ mechanism.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.517-521
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• 2006

네트워크 가상현실 시스템은 먼 거리에 떨어진 사용자들 사이에 일관성 있는 가상 세계를 제공하며, 군사, 오락, 건축 등 여러 부분에 응용되고 있다. 본 논문에서는 그 동안 고성능 그래픽 워크스테이션 환경에서 중심적으로 연구되어 왔던 네트워크 가상현실 시스템을 가장 보편적인 플랫폼인 네트워크 환경에서 구현할 때 생기는 3차원 그래픽 처리 성능의 문제 등과 같은 이에 대한 해결책들을 제시하고 미로 환경과 지형 환경에 근거한 가상 세계를 응용 실험 대상으로 삼아 성능을 분석하였다. 실시간으로 상호 작용하는 어플리케이션은 성능을 유지하면서 모든 참가자들에게 동일한 뷰를 보여주는 것이 중요하다. 동일한 뷰를 제공하기 위해 참가자들이 전송하는 이벤트마다 재생 지연 시간을 설정하고, 수신한 이벤트에 대해서는 예정 재생 시각까지 버퍼에 저장하여 모든 참가자들이 동시에 이벤트를 실행하도록 하는 기법이 제안되어 왔다. 그러나 네트워크 트래픽이 동적으로 변하므로 네트워크 상에서 발생하는 전송 지연 시간도 동적으로 변화한다. 그러므로 고정된 재생 지연 시간을 사용할 경우, 네트워크 트래픽 감소에 따라 상호 작용 성능을 향상시킬 수 있는 기회를 상실하게 되고, 네트워크 트래픽 증가에 따라 이벤트 손실률이 크게 증가하게 되어 참가자들 간에 일치하지 않는 뷰를 초래하게 된다. 네트워크 트래픽이 적어서 전송 지연 시간이 짧을 경우 짧은 재생 지연 시간을 적용하여 상호작용 성능을 높여주고, 트래픽이 많은 경우에는 재생 지연 시간을 늘림으로써 상호 작용 성능을 해치지 않는 범위에서 이벤트 손실률을 줄인다. 실험을 통하여 제안하는 기법의 성능을 평가하였으며 그 결과 본 동기화 기법이 고부하(heavily loaded) 네트워크 상태가 지속되는 동안 기존 기법에 비해 참가자들에게 일치된 뷰를 제공할 수 있고, 저부하(lightly loaded) 네트워크 상태에서는 상호 작용 성능을 향상시킬 수 있다는 것을 확인하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2770-2776
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• 2015

The development of efficient wearable antennas is required to implement short range body-centric wireless communication links for various internet of thing applications. We present simulation and measurement results of conductive-fiber-based wearable antennas which can comfortably fabricated directly on usual clothing materials. The proposed antenna is a form of a rectangular patch antenna designed by weaving conductive fibers on a felt substrate. A full-wave electromagnetic simulation tool is used to investigate the antenna performance such as antenna impedance, resonant frequency, and radiation efficiency. Parametric studies show that the radiation efficiency increases from 67.5% to 70.4% by widening the gap between conductive fibers from 0.25mm to 3mm. This implies a wearable antenna with good radiation efficiency can be designed despite of less portion of conductive fibers on the antenna. The simulation results are also verified by measured results with fabricated antennas.

• Journal of Elementary Mathematics Education in Korea
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• v.11 no.1
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• pp.81-98
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• 2007

In order to help students learn geometric concepts in mathematics in an easy and interesting way, the present study restructured the textbook so that it utilizes GSP based on van Hiele's theory. In addition, we purposed to examine how effective the restructured textbook is in enhancing students' van Hiele level and to lay a base for the active use of GSP in learning figures in elementary school. In conclusion, the results of this study is expected to solve problems in the structure of the current textbook such as the violation of continuity in van Hiele's theory and inconsistency between the level of textbook contents and students' level through the restructuring of the textbook using GSP and provide helps for effective figure learning. In addition, this research is expected to be an opportunity for the active use of GSP in teaching figures in elementary school.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.233-244
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• 2015

Marine ecosystem modelling has become a more widely used decision-making tool in coastal ecosystem-based management. However, it is not trivial to develop a well calibrated/validated model with potential applicability and practicality because understanding ecological processes with complexities is a pre-requisite for developing robust ecosystem models and this accompanies a great deal of well coordinated efforts among field-going ecologists, laboratory scientists, modelers, stake-holders and managers. This report aims to provide a brief introduction on two different approaches in marine ecological models: deterministic (mechanistic) and stochastic (statistical) approach. We also included definitions, historical overview of past researches, case studies, and contextual suggestions for coastal management in Korea. A long list of references this report included in this study might be used as an introductory material for those who wish to enter ecosystem modelling field.

• Journal of Digital Convergence
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• v.14 no.2
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• pp.169-173
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• 2016

With the rapid growth of IT technology and development of online shopping, e-commerce activity through online environment is going to grow in various forms. And then the intense competition also more deepen in the companies within the online market. The study on the various contents production and environment configuration for sale strategies has been made. Among online market products, it is needed to develop marketing strategies for online sales related to rings products. In this paper, through the analysis of online content and components of companies, it has obtained the appropriate components in the ring industry. In particular, aiming to young customers, we looked about components suitable for them and built site. As a result based on the above analysis, we anticipate that it will be able to see forward to a competitive ring marketing.