• 한국정보통신학회논문지
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• 제20권4호
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• pp.786-792
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• 2016

Camellia 암호는 NTT사 및 미쓰비시 전자회사에서 공동으로 2000년도에 개발되었다. Camellia는 128비트 메시지 블록 크기와 128비트, 192비트 및 256비트 키(Key)에 대한 암호화 방식을 규정하고 있다. 본 논문은 키 스케줄용 레지스터 설정과 기존의 라운드 연산 블록을 통합한 수정된 라운드 연산 블록을 제안하였다. 키 생성과 라운드 연산에 필요한 총 16개의 ROM을 단지 4개의 이중포트 ROM만을 사용하여 구현하였다. 또한 메시지 버퍼를 제공하여 키 생성을 위한 KA와 KB 값이 도출되면 대기 시간없이 즉시 암호화나 복호화가 수행될 수 있도록 하였다. 제안한 Camellia 블록 암호 알고리즘을 Verilgo-HDL을 사용하고 설계하고, Virtex4 디바이스상에 구현하였으며, 최대 동작 주파수는 184.898MHz이다. 128비트 키 모드에서 최대 처리율은 1.183Gbps이며, 192비트 및 256비트 키 모드에서 최대 처리율은 876.5Mbps이다. 본 논문에서 설계된 암호 프로세서는 스마트 카드, 인터넷뱅킹, 전자상거래 및 위성 방송 등과 같은 분야의 보안 모듈로 응용이 가능할 것으로 사료된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.496-500
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• 2001

When we cut a key way on the axial or on the boss, we generally use a slotter or a broach. To do the key seating, turing operations have to be preceded and then the key on the axial or on the boss can be seated. For this reason, the production process of key way cutting becomes complicated. If is necessary to simplify the process and we have developed a small practical machine for key way cutting. The machine is located on the carriage of the lathe. Using this small and practical key way machine, after operation the turing, you do not have to remove the workpiece from the chuck of the lathe to carry on the key seating process. The developed machine will save cutting time and the cost.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1247-1252
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• 2004

ATC(Automatic Train Control) system employed in Bundang urban transit is operated in accordance with automatic blocking equipment. Using AF(Audio Frequency) track circuits installed at a block section, the block signal is automatically controlled and the safety of train operation is supported. In this paper, we investigate the operation mode of bundang urban transit and analyze the operation algorithm of ATC on-board system.

• 컴퓨터교육학회논문지
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• 제9권2호
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• pp.111-124
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• 2006

오늘날 인터넷상에서 멀티캐스트 서비스가 급속도로 증가하고 있으며 이에 따라 멀티캐스트 통신의 보안을 유지하는 것이 중요하다. 그룹의 멤버가 제거되면 새로운 그룹키를 생성하여 그룹의 나머지 모든 멤버들에게 전달되어야 한다. 새로운 키를 생성하여 분배하는 것은 많은 연산을 요구하므로 rekey하기 위하여 보내는 메시지의 수와 복합키를 생성하기 위한 연산비용을 최소화하는 것은 키 관리기법을 평가하는 중요한 기준이다. 주기적인 일괄제거는 멤버를 순차적으로 1개씩 제거하는 것보다 rekey에 대한 메시지의 수와 복합키의 연산 비용을 줄일 수 있다. 본 논문에서는 그룹에서 제거될 멤버들간의 해밍거리가 임계치보다 작은 멤버들만 동시에 제거된다. 여러 개의 멤버를 제거할 때 라운드 조정 알고리즘을 수행하면 rekey를 위하여 메시지의 수와 복합키를 생성하기 위한 연산의 비용을 줄이며 공모공격의 가능성이 제거되는 이점이 있다. 시뮬레이션을 통하여 라운드 조정알고리즘을 적용한 결과의 성능을 평가하며 기존의 기법과 비교를 하여 본 논문에서 제안하는 기법이 우수함을 보인다.

• Journal of Power Electronics
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• 제14권2호
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• pp.249-256
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• 2014

A novel topology generation method for the no dead-time three-phase AC/DC converter is proposed in this study. With this method, a series of no dead time topologies are generated and their operation principles are analyzed. The classic three-phase bridge AC/DC converter can realize a bidirectional operation. However, dead-time should be inserted in the driving signals to avoid the shoot-through problem, which would cause additional harmonics. Compared with the bridge topology, the proposed topologies lack the shoot-through problem. Thus, dead time can be avoided. All of the no dead time three-phase AC/DC converters can realize bidirectional operation. The operating principles of the converters are analyzed in detail, and the corresponding control strategies are discussed. Comparisons of waveform distortion and efficiency among the converters are provided. Finally, 9 KW DSP-based principle prototypes are established and tested. Simulation and experimental results verify the theoretical analysis.

• Journal of the Optical Society of Korea
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• 제17권1호
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• pp.5-9
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• 2013

We report on high-power continuous-wave operations of an Er:YAG ceramic laser in-band pumped by a cladding-pumped Er,Yb fiber laser at 1532 nm. With an output coupler of 10% transmission, the ceramic laser yielded 16.7 W of continuous-wave output at 1645 nm for 28.8 W of incident pump power, corresponding to a slope efficiency of 61.0% with respect to the incident pump power. The lasing wavelength switched to 1617 nm when output couplers of > 20% transmission were used. Up to 16.2 W of 1617 nm output was generated for 33.0 W of incident pump power, corresponding to a slope efficiency of 51.8%. Graphene Q-switched operation of Er:YAG cermic laser at 1645 nm was also demonstrated with stable pulses of 30-74 kHz repetition rates and 1.5-6.4 ${\mu}s$ pulse widths.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2840-2851
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• 2022

Electric boilers (EBs) are the backup steam source for the auxiliary steam system of high-temperature gas-cooled reactor nuclear power plants. When the plant is in normal operations, the EB is always in hot standby status. However, the current hot standby operation strategy has problems of slow response, high power consumption, and long operation time. To solve these problems, this study focuses on the optimization of hot standby operations for the EB system. First, mathematical models of an electrode immersion EB and its accompanying deaerator were established. Then, a control simulation platform of the EB system was developed in MATLAB/Simulink implementing the established mathematical models and corresponding control systems. Finally, two optimization strategies for the EB hot standby operation were proposed, followed by dynamic simulations of the EB system transient from hot standby to normal operations. The results indicate that the proposed optimization strategies can significantly speed up the transient response of the EB system from hot standby to normal operations and reduce the power consumption in hot standby operations, improving the dynamic performance and economy of the system.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제11권4호
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• pp.247-263
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• 2007

Problem solving takes place not only in mathematics classes but also in real-world. For this reason, a problem and the structure of problem solving, and the enhancing of success in problem solving is a subject which has been studied by any educators. In this direction, the aim of this study is that the strategy used by students in Turkey when solving oral problems and their achievements of choosing operations when solving oral problems has been researched. In the research, the students have been asked three types of questions made up groups of 5. In the first category, S-problems (standard problems not requiring to determine any strategy but can be easily solved with only the applications of arithmetical operations), in the second category, AS-SA problems (problems that can be solved with the key word of additive operation despite to its being a subtractive operation, and containing the key word of subtractive operation despite to its being an additive operation), and in the third category P-problems (problematic problem) take place. It is seen that students did not have so much difficulty in S-problems, mistakes were made in determining operations for problem solving because of memorizing certain essential concepts, and the succession rate of students is very low in P-problems. The reasons of these mistakes as a summary are given below: $\cdot$ Because of memorizing some certain key concepts about operations mistakes have been done in choosing operations. $\cdot$ Not giving place to problems which has no solution and with incomplete information in mathematics. $\cdot$ Thinking of students that every problem has a solution since they don't encounter every type of problems in mathematics classes and course books.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1377-1379
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• 2003

Satellite and aerial remote sensing (RS) techniques have been provided to collect spatial data globally over the last few decades. However in developing countries such as China, there is still an urgent need for low cost and high resolution RS data. As an emerging RS platform, commercial Unmanned Aerial Vehicle (UAV) integrated with state-of-the-art sensors and information technologies has the potential to become a low cost tool to meet application demands. In this paper, the architecture of UAV RS operation system is mentioned. Moreover, key technologies in UAV RS system are analyzed and current work is reported.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.345-348
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• 2002

This paper presents new fast scalar multiplier of elliptic curve cryptosystem that is regarded as next generation public-key crypto processor. For fast operation of scalar multiplication a finite field multiplier is designed with LFSR type of bit serial structure and a finite field inversion operator uses extended binary euclidean algorithm for reducing one multiplying operation on point operation. Also the use of the window non-adjacent form (WNAF) method can reduce addition operation of each other different points.