• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.10
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• pp.89-96
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• 2003

In this paper, a CCSDS(Consultative Committee for Space Data Systems) telecommand(TC) decryptor for the security of geostationary communications satellite was implemented. For the confidentiality of CCSDS TC datalink security, Option-A which implements the security services below the transfer sublayer was selected. Also CFB(Cipher Feedback) operation mode of DES(Data Encryption Standard) was used for the encryption of 56-bit data bits in 64-bit codeblock. To verify Decryptor function, the DES CFB logic implemented on A54SX32 FPGA(Field Programmable Gate Array) was integrated with interface and control logics in a PCB(Printed Circuit Board). Using a function test PC, the encrypted codeblocks were generated, transferred into the decryptor, decrypted, and the decrypted codeblocks were transmitted to the function test PC, and then compared with the source codeblocks. Through LED(Light Emitting Diode) ON operation by driving the relay related to Op-code decoded and the comparison between the codeblock output waveforms measured and those simulated, the telecommand decryptor function was verified.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.89-100
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• 2011

As the Internet usage with web browser is more increasing, the web-based malware which is distributed in websites is going to more serious problem than ever. The central type malicious website detection method based on crawling has the problem that the cost of detection is increasing geometrically if the crawling level is lowered more. In this paper, we proposed a security tool based on web browser which can detect the malicious web pages dynamically and support user's safe web browsing by stopping navigation to a certain malicious URL injected to those web pages. By applying these tools with many distributed web browser users, all those users get to participate in malicious website detection and feedback. As a result, we can detect the lower link level of websites distributed and dynamically.

• Journal of KIISE:Databases
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• v.37 no.2
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• pp.82-91
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• 2010

Data compression technique is traditional and effective to reduce network traffic. Generally, sensor data exhibit strong correlation in both space and time. Many algorithms have been proposed to utilize these characteristics. However, each sensor just utilizes neighboring information, because its communication range is restrained. Information that includes the distribution and characteristics of whole sensor data provide other opportunities to enhance the compression technique. In this paper, we propose an orthogonal approach for compression algorithm based on a novel feedback diffusion algorithm in sensor networks. The base station or a super node generates the Huffman code for compression of sensor data and broadcasts it into sensor networks. Every sensor that receives the information compresses their sensor data and transmits them to the base station. We define this approach as feedback-diffusion. In order to show the superiority of our approach, we compare it with the existing aggregation algorithms in terms of the lifetime of the sensor network. As a result, our experimental results show that the whole network lifetime was prolonged by about 30%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.9
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• pp.721-727
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• 2012

Since a conventional multi-cell transmit diversity scheme depends on the feedback from the user for the channel gain information, its performance gets to severely degrade when the channel varies fast due to the high mobility of the user. Also, transmit power of the base station cannot be fully used in the conventional scheme because only one transmit antenna is used for data transmission. In this paper, we propose a multi-cell transmit diversity scheme appropriate for fast fading channel. In the proposed scheme, channel-independent precoding vector is applied over all transmit antennas and different precoding vectors are applied for neighboring subcarriers so that the received signal is avoided to experience deep fading over multiple neighboring subcarriers. Simulation results show that the proposed scheme has better detector output signal-to-noise ratio (SNR) and bit error rate (BER) performances than the conventional scheme.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.238-247
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• 2004

Realtime Simulation and HILS are essential tools for modern aircraft control system design and development. But developing the HILS has been a big and complex task to meet the realtime simulation requirement. So these days there have been efforts to minimize these task. New advanced concept and design tools are being developed. In this paper, these new advanced concept and design tools were used to develop the realtime simulation and HILS environment for rotorcraft. The H/W 문 S/W requirement and system configuration for the developing system will be described on the paper.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.5
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• pp.16-24
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• 2011

The IEEE 802.11 wireless LAN (Local Area Network) is widely used for wireless access due to its easy deployment and low cost. Multicast in wireless LANs is very useful for transmitting data to multiple receivers compared to unicast to each receiver. In the IEEE 802.11 wireless LAN, multicast transmissions are unreliable since multicast data packets are transmitted without any feedback from receivers. Recently, various protocols have been proposed to enhance the reliability of multicast transmissions. They still have serious problems in reliability and efficiency due to the excessive control overhead by the use of a large number of control packets in the error recovery process, and due to a large number of retransmissions to satisfy all receivers. In this paper, we propose an effective scheme called PTRM(Proactive Transmission based Reliable Multicast). The proposed scheme uses a block erasure code to generate parity packets and to reduce the impact of independent packet error among receivers. After generating parity packets, the PTRM transmits data packets as many as receivers need to recover error, and then requests feedback from them. The simulation results show that the proposed scheme provides reliable multicast while minimizing the feedback overhead.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.417-418
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• 2018

오늘날 SW 중심사회에서 컴퓨팅 사고력은 꼭 필요한 핵심역량으로 중요성이 강조되고 있으며, 이에 따라 2015 개정 교육과정에서는 소프트웨어(SW) 교육, 정보 교육을 강화하였다. 온라인 채점 시스템은 학생들이 문제해결 소스코드를 제출하면 이를 평가하고, 적절한 피드백을 제공하므로 자기주도적인 문제해결학습 경험과 프로그래밍 스킬을 향상시키는데 도움을 줄 수 있어 사용이 확대되고 있다. 그러나 채점시스템에 탑재된 문제들은 반구조화된 형태로 되어 있어 학생들이 컴퓨팅 사고단계 중 1단계인 문제공식화(추상화) 단계를 충분히 연습하지 못할 가능성이 있다. 본 논문에서는 이를 보완한 문제해결학습 학습모형을 제안하고, 논의한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.282-283
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• 2017

A government or non-governmental organization give service to their customer. Each organization have different hierarch levels. Service satisfaction surveys have become an important tool for government planners, as important in the perceived quality of service lead to great delivery of public service. When a customer gives feedback at a bottom level of organization, it is so difficult reach to higher official in time. This paper argue that, Quick Response (QR) code open up the possibility of conducting public service satisfaction at lower cost and the way feedback is directly routed to the relevant party according to their hierarchical level and gate real time feedback using specific smart phone application.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.01a
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• pp.221-222
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• 2023

본 연구에서는 주피터 노트북에서 자동 평가 시스템을 활용하기 위한 방안으로 자동 평가 시스템의 문제를 저장하고 제시하는 방안에 대해서 연구하였다. 자동 평가 시스템은 학습자가 직접 프로그래밍을 하고 바로 피드백을 받을 수 있는 장점이 있다. 주피터 노트북에서 자동 평가 시스템을 제공하는 nbgrader와 코들의 장점을 바탕으로 문제 제시 방안은 다음과 같다. 문제는 HTML 태그를 이용해 서식 있는 형태로 서버에 저장한다. 주피터 노트북에서 IPython.display 모듈의 display와 HTML 명령어를 사용하여 문제를 출력하면 코드셀 출력창에 서식 있는 HTML 문서를 출력하여 학습자에게 가독성 있게 문제를 제시할 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2775-2782
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• 2010

In this paper, we propose a web-based programming class support system to help a lecturer to teach a programming language to students effectively. The proposed system is composed of a error analysis step and a verification step. The error analysis step checks whether there are compile time errors or run time errors in each student's submitted program. Given some errors, the system provides helpful feedback for the student to fix the errors. On the contrary, the system provides quick feedback after checking the source code style, comments, and plagiarism in the submitted program. As soon as the student submits the program, the student can see the check results. According to the result of utilizing the proposed system in a C programming language class, students tend to submit program assignments actively.