• Journal of Korea Society of Industrial Information Systems
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• v.24 no.2
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• pp.1-14
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• 2019

Since most documents used in web, XML, office applications are tree-structured, diff, merge, and version control for tree-structured documents in multi-user environments are crucial tasks. However research on edit scripts which is a basis for them is in primitive stage. In this paper, we present a document model for understanding the change of tree-structured documents as edit scripts are executed, and propose a method of switching adjacent edit operations on tree-structured documents based on the analysis of the effects of edit operations. Mostly, edit scripts which are produced as the results of diff on tree-structured documents only consist of basic operations such as update, insert, delete. However, when move and copy are included in edit scripts, because of the characteristics of their complex operation, it is often that edit scripts are generated to execute in two passes. In this paper, using the proposed method of switching edit operations, we present an algorithm of transforming the edit scripts of X-treeESgen, which are designed to execute in two passes, into the ones that can be executed in one pass.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.5
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• pp.3-15
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• 2003

The secure group communication enables the members, which belong to the same group, to communicate each other in a secure and secret manner. To do so, it is the most important that a group key is securely distributed among them and also group membership is efficiently managed. In detail, the generation, the distribution and the refreshment of a group key would be highly regarded in terms of low communication and computation complexity. In this paper, we show you a new protocol to generate a group key which will be safely shared within a group, utilizing the 2-party Diffie-Hellman key exchange protocol and the complete binary tree. Our protocol has less complexity of computation per group member by substituting many parts of exponentiation computations for multiplications. Consequently, each group member needs constant computations of exponentiation and multiplication regardless of the group size in the protocol and then it has less complexity of the computation than that of any other protocols.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.4
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• pp.85-98
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• 2003

Computational power of IC chip is improved day after day producing IC chips holding co-processor continuously. Also a lot of wireless terminals which IC chip embedded in are produced in order to provide simple and various services in the wireless terminal market. However it is difficult to apply the key distribution protocol under wired communication environment to wireless communication environment. Because the computational power of co-processor embedded in IC chip under wireless communication environment is less than that under wired communication environment. In this paper, we propose the hey distribution protocol appropriate for wireless communication environment which diminishes the computational burden of server and client by using co-processor that performs cryptographic operations and makes up for the restrictive computational power of terminal. And our proposal is satisfied with the security requirements that are not provided in existing key distribution protocol.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.4
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• pp.21-28
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• 2009

In the recent years, power attacks were widely investigated, and so various countermeasures have been proposed, In the case of block ciphers, masking methods that blind the intermediate values in the algorithm computations(encryption, decryption, and key-schedule) are well-known among these countermeasures. But the cost of non-linear part is extremely high in the masking method of block cipher, and so the inversion of S-box is the most significant part in the case of AES. This fact make various countermeasures be proposed for reducing the cost of masking inversion and Zakeri's method using normal bases over the composite field is known to be most efficient algorithm among these masking method. We rearrange the masking inversion operation over the composite field and so can find duplicated multiplications. Because of these duplicated multiplications, our method can reduce about 10.5% gates in comparison with Zakeri's method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.4
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• pp.548-555
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• 2022

This paper describes the hardware implementation of elliptic curve cryptography (ECC) used as a core operation in elliptic curve digital signature algorithm (ECDSA). The ECC processor supports eight operation modes (four point operations, four modular operations) on the NIST P-521 curve. In order to minimize computation complexity required for point scalar multiplication (PSM), the radix-4 Booth encoding scheme and modified Jacobian coordinate system were adopted, which was based on the complexity analysis for five PSM algorithms and four different coordinate systems. Modular multiplication was implemented using a modified 3-Way Toom-Cook multiplication and a modified fast reduction algorithm. The ECC processor was implemented on xczu7ev FPGA device to verify hardware operation. Hardware resources of 101,921 LUTs, 18,357 flip-flops and 101 DSP blocks were used, and it was evaluated that about 370 PSM operations per second were achieved at a maximum operation clock frequency of 45 MHz.

• Communications of Mathematical Education
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• v.13 no.1
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• pp.19-38
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• 2002

알고리즘이란 ‘유한한 단계를 거쳐 일련의 문제를 해결하기 위한 명확하고 체계적인 방법’ 으로써 수량에 관련된 문제를 보다 신속 ${\cdot}$ 정확하게 처리하기 위하여 역사적으로 다양한 알고리즘이 존재 ${\cdot}$ 변천해 왔다. 계산기가 발명되기 전까지는 지필 알고리즘이 매우 강조되어 왔으나 계산기가 상용화되면서 지필알고리즘에 대한 효용성과 활용도가 점차 줄어들고 있으나 지필 알고리즘은 수학학습의 기초 ${\cdot}$ 기본인 동시에 뼈대로써 그 가치와 역할은 여전히 중요하다. 그러나 표준화된 지필 알고리즘에 대한 지나친 강조로 인해 학생들은 대수적 구조나 계산 원리를 바르게 이해하지 못한 채 반복 연습을 통해 익힌 표준 알고리즘을 기계적으로 적용하여 답을 구하는 경우가 많으며, 이로 인해 학생들은 수학학습에 대한 불안감과 기피현상이 보이고 있다. 또 인간의 창조적 사고활동의 최종적인 산물인 표준 알고리즘은 대안적인 알고리즘에 비해 효율성에서 앞서지만 학생들의 사고 수준에서는 그 원리를 이해하기 힘든 경우가 있을 것이다. 따라서 수학교육의 목적 중의 하나인 문제 해결력을 기르기 위해, 그리고 표준 알고리즘의 가치와 효율성을 인식시키고, 수학학습에 대한 불안감을 줄이기 위해 표준 알고리즘뿐만 아니라 대안적인 알고리즘을 병행하여 지도할 필요가 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.293-296
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• 2010

현재 지능형 서비스로봇이 활성화되고 있으며 지능형 로봇 분야에서 청소로봇은 개인생활의 본질적인 운동성을 보조하며 인간과 공생의 형태를 지원하는 로봇으로 성장하고 있다. 청소로봇은 가정에서 다양한 서비스를 제공하기 위하여 가정환경과 적절한 상호작용은 필수적이다. 따라서 로봇이 외부의 서버와 협동을 통한 원격제어는 필수적이라 할 수 있다. 현재 지도 작성이 가능한 청소로봇은 바닥에 센서를 부착하거나 작업환경에 카메라 및 기타 많은 장치를 구축하므로 고가의 장비로 분류되어 일반적으로 활용지 못하고 있다. 본 연구에서는 청소로봇의 효율적인 제어를 위하여 작업환경에서 로봇의 궤적과 센서정보를 원격으로 서버에 전달하고 서버는 이러한 정보를 바탕으로 지도를 작성하고 최적의 작업을 수행할 수 있는 알고리즘을 연산하여 로봇에 전달할 수 있는 방법을 연구하였다. 이는 로봇이 지도 작성을 위한 연산 과정을 줄이므로 수행 시간을 단축하고 로봇에 주어지는 부하를 줄일 수 있다. 또한 원격으로 제어를 수행하므로 무선통신이 가능한 각종 디바이스와 상호 연동할 수 있는 체계를 만들어 유비쿼터스 환경을 구축할 수 있는 계기를 만들므로 청소로봇의 성능이 향상될 수 있음을 보인다. 본 연구에서는 청소로봇을 제작하고 시뮬레이션과 실험을 통하여 전체적으로 주어진 작업을 효율적으로 수행할 수 있음을 보여준다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.161-166
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• 2018

In this paper, we propose a method for the random selection of pooling operations for the regularization and reduction of cross validation in convolutional neural networks. The pooling operation in convolutional neural networks is used to reduce the size of the feature map and for its shift invariant properties. In the existing pooling method, one pooling operation is applied in each pooling layer. Because this method fixes the convolution network, the network suffers from overfitting, which means that it excessively fits the models to the training samples. In addition, to find the best combination of pooling operations to maximize the performance, cross validation must be performed. To solve these problems, we introduce the probability concept into the pooling layers. The proposed method does not select one pooling operation in each pooling layer. Instead, we randomly select one pooling operation among multiple pooling operations in each pooling region during training, and for testing purposes, we use probabilistic weighting to produce the expected output. The proposed method can be seen as a technique in which many networks are approximately averaged using a different pooling operation in each pooling region. Therefore, this method avoids the overfitting problem, as well as reducing the amount of cross validation. The experimental results show that the proposed method can achieve better generalization performance and reduce the need for cross validation.

• The Mathematical Education
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• v.30 no.2
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• pp.107-123
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• 1991

• School Mathematics
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• v.10 no.4
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• pp.537-555
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• 2008

The study aims to analyze elementary school students' understanding of the concept of equality sign in contexts, to reflect the types of contexts for equality sign which mathematics textbook series for $1{\sim}4$ grades on natural numbers and its operation provide, and to invetigate the effects of teaching methods of the concept of equality sign suggested in this research. In order to achieve these purposes, the origin, concept, and contexts of equality sign were theoretically reviewed and organized. Also the error types in using equality sign were reflected. Modelling, discussing truth or falsity of equations, identifying relations between numbers and their operation, conjecturing basic properties of numbers and their operations, experiencing diverse contexts for equality sign, and creating contexts for equality sign are set up as teaching methods for better understanding the concept of equality sign. The conclusions are as follows. Firstly, elementary school students' under-standing of the concept of equality sign varied by context and was generally far from satisfactory. In particular, they had difficulties in understanding the concept of the equal sign in contexts with operations on both sides. The most frequently witnessed error was to recognize equality sign as a result of operations. Secondly, student' lack of understanding of the concept of equality sign came from the fact that elementary textbooks failed to provide diverse contexts for equality sign. According to the textbook analysis, contexts with operations on the left side of the equal sign in the form of $a{\pm}b=c$ were provided excessively, with the other contexts hardly seen. Thirdly, teaching methods provided in the study were found to be effective for enhancing understanding the concept of equality sign. In other words, these methods enabled students to focus on relational understanding of concept of equality sign rather than operational one.