• Communications of Mathematical Education
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• v.25 no.3
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• pp.607-627
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• 2011

The purpose of this study is to analyse teaching and learning effects of the structural-mapping used instruction and to find out the characteristics of problem solving process in permutation and combination. For this study, two classes of 11th grade students(67 students) were randomly selected from S high school in D city. One of them was assigned to the experimental group and the other to the control group, respectively. Four lectures of the structural-mapping used instruction were carried out in the experimental group and same amount of lectures of the text book oriented instruction were carried out in the control group. The research findings are as follows. First, the structural-mapping used instruction is shown to be more effective in achievement than the traditional textbook-oriented instruction. Second, the ball-box model is found out to be easier and simpler than the selection-distribution model. Third, students who used the ball-box model are properly able to use both model.

• Annual Conference on Human and Language Technology
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• 1992.10a
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• pp.85-93
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• 1992

본 논문은 한글-한자 변환에 있어서 여러 대응 한자를 갖는 동형이의어의 모호성 해소 방법을 제안한다. 기존의 변환 방법은 사용자의 개입으로 이루어지므로, 사용자에게 많은 부담을 주고 변환 효율을 떨어뜨린다. 한자선택에 있어서 동형이의어 문제의 근본적 해결을 위해, 본 시스템에서는 의미 분석을 이용한 한글-한자 변환기를 제안한다. 이를 위해 격문법과 관련어 지식 베이스(thesaurus)를 사용한다. 격문법을 사용하여 서술어를 중심으로 관련된 격틀의 의미를 분석한다. 그리고 합성어의 경우에 합성어의 구성 형태에 따라 격문법을 사용하거나 관련어 지식 베이스에서의 의미 근접성을 사용한다. 본 논문은 이와 같이 의미 분석 및 개념 정보를 기반으로 하는 동형이의어의 모호성 해결 방안을 제시하고 이를 반영한 한글-한자 변환 시스템의 설계 및 구현에 관하여 기술한다.

• Convergence Security Journal
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• v.19 no.3
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• pp.61-70
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• 2019

Recently, developments on quantum computers and cloud computing have been actively conducted. Quantum computers have been known to show tremendous computing power and Cloud computing has high accessibility for information and low cost. For quantum computers, quantum error correcting codes are essential. Similarly, cloud computing requires homomorphic encryption to ensure security. These two techniques, which are used for different purposes, are based on similar assumptions. Then, there have been studies to construct quantum homomorphic encryption based on quantum error correction code. Therefore, in this paper, we propose a scheme which can process the homomorphic encryption like quantum computation by modifying the QECCs. Conventional quantum homomorphic encryption schemes based on quantum error correcting codes does not have error correction capability. However, using the proposed scheme, it is possible to process the homomorphic encryption like quantum computation and correct the errors during computation and storage of quantum information unlike the homogeneous encryption scheme with quantum error correction code.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.725-726
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.43-44
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• 2010

• The Journal of the Korea Contents Association
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• v.21 no.9
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• pp.42-50
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• 2021

As the Internet environment develops, data-analysis-based applications have been widely and extensively used in the past decade. However, these applications potentially have a privacy problem in that users' personal information may be leaked to unauthorized parties. To tackle such a problem, researchers have suggested several techniques including data perturbation and cryptography. The homomorphic encryption algorithm is a relatively new cryptography technology that allows arithmetic operations for encrypted values as it is without decryption. Since original values are not required, we believe that this method provides better privacy protection than other existing solutions. In this work, we propose to apply a homomorphic encryption algorithm that protects personal information while enabling data analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1904-1913
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• 2021

With the proliferation of smart phones and the development of IoT technology, it has become possible to collect personal data for public purposes. However, users are afraid of voluntarily providing their private data due to privacy issues. To remedy this problem, mainly three techniques have been studied: data disturbance, traditional encryption, and homomorphic encryption. In this work, we perform simulations to compare them in terms of accuracy, message length, and computation delay. Experiment results show that the data disturbance method is fast and inaccurate while the traditional encryption method is accurate and slow. Similar to traditional encryption algorithms, the homomorphic encryption algorithm is relatively effective in privacy preserving because it allows computing encrypted data without decryption, but it requires high computation costs as well. However, its main cost, arithmetic operations, can be processed in parallel. Also, data analysis using the homomorphic encryption needs to do decryption only once at any number of data.

• Journal of KSNVE
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• v.11 no.3
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• pp.401-409
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• 2001

Passive type mufflers installed on every car haute inherent problem of lowering engine power and fuel efficiency caused by backpressure which is byproduct of complex internal structure. Recent improvements like installing a calve to change exhaust gas path depending on power requirement and rpm have only marginally improved performance. Tremendous amount of recent research works on active exhaust noise control have failed to commercialize because of numerous physical and economical reasons. In this paper, a unique seal-active muffler using difference of transmission paths is presented. In this system exhaust pipe is divided into two and joined again downstream. Exhaust noise is reduced by destructive interference when two-divided noise join again with transmission paths'difference which is half of the wavelength of a main noise frequency. One divided path has a sliding mechanism to change length thereby transmission path length difference is adjusted to entwine rpm change. The proposed system has minimal backpressure and does not need a secondary sound source like a speaker so it can overcome many problems of failed active noise control methods. We have verified proposed system's superior performance by simulation and comparison experiment with passive mufflers.

• Journal of the Korean Geographical Society
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• v.39 no.4
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• pp.562-584
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• 2004

This paper intends to identify the structure of homogeneous regions and functional regions in Seoul based on B.J.L. Berry's ‘general field theory of spatial behavior’. The structure of homogeneous regions by using socio-economic variables can explain how the structural elements of the city are arranged. It can be ssid that Seoul has shifted towards more complicated and differentiated features in terms of homogeneous regions. The different patterns are found between the northern part to Han River where old torn areas are located and the southern part to Han River where newly urbanized areas are located. Usually, the concentric pattern and the sectoral pattern coexist, which is enhanced moving from CBD to the outskirt area. The distribution of different social classes shows irregular pattern similar to the variation of living environment. The social gap is expected to be more widening between new towns and old towns. The analysis of spatial movement pattern shows no clear hierarchical order because of current shifts towards both multi-nuclear pattern and spatial dispersion. The functional regions show duplicated structure overlapping their boundaries each other. The ‘general field theory of spatial behavior’ strongly suggests that spatial interactions among sub-areas in the city are differentiated from the basic characteristics and function of each sub-area. The attributes of homogeneous regions and functional regions are interrelated in the characteristics of isomorphic nature.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.606-608
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• 1995

A thermally actuated micro-relay using a mercury-contact has been designed and fabricated. The mercury actuation was achieved by external nitrogen pressure and the mercury-contact was moved by actuation pressure of 110torr in the 100${\mu}m$ wide microchannel. The Injection pressure of mercury was 300torr in the 60${\mu}m$ wide microchannel of the micro relay structure.