• 한국CDE학회논문집
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• 제11권5호
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• pp.327-334
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• 2006

Recently, security incidents are growing rapidly in which internal employees let the drawing leak out to competitors or other countries. This type of security incidents has a characteristic that it occurs less frequently than other types of security incidents such as network or server security incident, but the damage is a lot more serious. The existing information security technologies to prevent internal information from being leaked out are only applicable to general documents(office documents, web pages and image files in which data are encrypted one by one). However, architectural drawings made up of collection of files with various formats(extensions) have problems with the process speed of en(de) cryption and accuracy, so the developments of security technologies by new methods are required. In this study, we design and develop a security technology based on work area with which users can protect the leakage of critical information in the kernel level while maintaining their work environment when they have to use sharing information that cannot be managed by the unit of file. As a result, we developed the "Virtual Secure Disk" which allows only authorized users and applications to have an access to drawings, and have verified its security by applying it to the actual company.

• 전기학회논문지P
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• 제51권1호
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• pp.18-27
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• 2002

This paper presents an implementation of digital high-performance speed sensorless control system of an induction motor drives with Direct Torque Control(DTC). The system consists of closed loop stator flux and torque observer, speed and torque estimators, two hysteresis controllers, an optimal switching look-up table, IGBT voltage source inverter, and TMS320C31 DSP controller board. The stator flux observer is based on the combined current and voltage model with stator flux feedback adaptive control for wide speed range. The speed estimator is using the model reference adaptive system(MRAS) with rotor flux linkages for speed turning signal estimation. In order to prove the suggested speed sensorless control algorithm, and to obtain a high-dynamic robust adaptive performance, we have some simulations and actual experiments at low(20rpm) and high(1000rpm) speed areas. The developed speed sensorless system are shown a good speed control response characteristic, and high performance features using 2.2[kW] general purposed induction motor.

• Smart Structures and Systems
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• 제4권6호
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• pp.741-757
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• 2008

The research field of structural control has evolved from the development of passive devices since 1970s, through the intensive investigation on active systems in 1980s, to the recent studies of semi-active control systems in 1990s. Currently semi-active control is considered most promising in civil engineering applications. However, actual implementation of semi-active devices is still limited due mainly to their system maintenance and associated long-term reliability as a result of power requirement. In this paper, the concept of functionally upgraded passive devices is introduced to streamline some of the state-of-the-art researches and guide the development of new passive devices that can mimic the function of their corresponding semi-active control devices for various applications. The general characteristics of this special group of passive devices are discussed and representative examples are summarized. Their superior performances are illustrated with cyclic and shake table tests of two example devices: mass-variable tuned liquid damper and friction-pendulum bearing with a variable sliding surface curvature.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
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• pp.284-287
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• 1987

In this paper, the design and implementation of a multiprocessor based Die Bonder Machine for the semiconductor will be described. This the partial research result, that is, the 1st year portion of the project to be performed for a period of two years from June, 1986 to May, 1988. The mechanical system consists of the following three subsystems : (i) transfer head unit, (ii) die feeding XY-table unit, and (iii) plunge up unit. The overall control system is designed to be essentially a master-slave type in which each slave is functionally fixed in view of software and also the time shared common bus structure with hardwired bus arbitration scheme is utilized, the control system consists of the following three subsystems each of which employs a 16 bits microprocessor MC 68000 : (i) die bonder processor controller, (ii) visual recognition/inspection and display system, (iii) the servo control system. It is reported that the proposed control system were applied to Working Sample and tested in real system, and the results are successful as a working sample phase.

• 디지털산업정보학회논문지
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• 제14권2호
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• pp.1-9
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• 2018

Currently, the record of part-timer is mainly written in handwriting or using excel work schedule, paper work recorder, and time attendance program using POS program. And, work table, commute records, paycheck are managed separately. Time-attendance information is not linked and is managed separately, and payment of wages is often not done accurately. And, it is difficult to pay the wages because it is not able to accurately grasp the state of attendance of part-timer. Therefore, it is necessary to have a transparent wage and work management system based on the trust between the owner and the part-timer. In this paper, we design a system that can perform real-time commute check using beacon, transparent wage management, wage calculation by automatic calculation, and smooth communication between owner and the part-timer. We have also implemented a store management mobile application using Android Studio 2.3, Eclipse, Android 5.1 and Beacon devices in a MySQL environment.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.424-428
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• 2004

XML 문서를 저장하고 검색하는 시스템에 관련된 연구가 활발하게 이루어지고 있으며, 이러한 시스템들은 효율적으로 XML 문서를 저장하고 검색할 수 있는 기능에 중점을 둔 경우가 많다. 또한 XML 문서를 저장하기 위해서 특별히 설계된 테이블이나 저장 구조를 가지고 있어서 XML 문서의 내용뿐만 아니라 문서의 구조 정보 둥도 같이 저장할 수 있으며 이를 바탕으로 XML 문서의 내용 검색이나 구조 검색 등을 효율적으로 할 수 있도록 하고 있다. 본 논문은 기존에 사용해 왔던 여러 종류의 데이터베이스들이 갖고 있는 데이터들을 그대로 재활용하여 XML 형식으로 변환하고, 이 XML 파일을 웹에서 공유하여 여러 가지 다양한 Interface를 통해 출력 될 수 있도록 설계, 구현하였다.

• 정보처리학회논문지C
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• 제9C권2호
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• pp.157-162
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• 2002

본 연구에서는 DES 알고리즘과 EDE 알고리즘을 이용한 데이터 암호화와 전자서명 기술을 접목한 인터넷 폰 보안 시스템을 구현하였다. 비밀키 알고리즘의 키 분배 문제를 해결하기 위하여 Diffie-Hellman 알고리즘을 이용한 새로운 키 분배 방법을 제안하였다. 그리고 암호화에 따른 전송지연 시간을 감소시키기 위해 DES 알고리즘의 S-Box와 P-Box를 하나의 테이블로 조합하여 운영하였다. 제안된 인터넷 폰 보안 시스템은 자바로 구현하였으며, 실험결과 DES 알고리즘을 이용할 경우 1.46초, EDE 알고리즘을 이용할 경우 3.25초의 전송지연 시간을 보였다 제안된 시스템에서 사용된 기술들은 향후 음향제작물의 저작권 보호와 인터넷을 이용하는 데이터의 보호에 적용할 수 있을 것으로 생각된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.598-601
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• 2003

Most of all, DTC drive is very simple in its implementation because it needs only two hysteresis comparator and switching vector table for both flux and torque control. The switching strategy of a conventional direct torque control scheme which is based on hysteresis comparator results in a variable switching frequency which depends on the speed, flux, stator voltage and the hysteresis of the comparator. The amplitude of hysteresis band greatly influences on the drive performance such as flux and torque ripple and inverter switching frequency. In this paper the influence of the amplitudes of flux and torque hysteresis bands and sampling time of control program on the torque and flux ripples are investigated. Simulation results confirm the superiority of the DTC under the proposed method over the conventional DTC.

• Journal of Power Electronics
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• 제19권6호
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• pp.1429-1439
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• 2019

Buck-Boost LLC (BBLLC) converters based on a PWM + phase control strategy are good candidates for high efficiency, high power density and wide input range applications. Nevertheless, they suffer from large computational complexity when it comes to calculating the optimal phase for ZVS of all the switches. In this paper, a method is proposed for a microcontroller unit (MCU) to calculate the optimal phase quickly and accurately. Firstly, a 2-D lookup table of the phase is established with an index of the input voltage and output current. Then, a bilinear interpolation method is applied to improve the accuracy. Meanwhile, simplification of the phase equation is presented to reduce the computational complexity. When compared with conventional curve-fitting and LUT methods, the proposed method makes the best tradeoff among the accuracy of the optimal phase, the computation time and the memory consumption of the MCU. Finally, A 350V-420V input, 24V/30A output experimental prototype is built to verify the proposed method. The efficiency can be improved by 1% when compared with the LUT method, and the computation time can be reduced by 13.5% when compared with the curve-fitting method.

• 한국컴퓨터정보학회지
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• 제2권1호
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• pp.45-54
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• 1995

본 연구는 ASCII 코드중에서 잘 쓰이지 않는 코드를 반달점(ˇ)으로 할당, 글꼴을 제작하여, 사용자가 국어 로마자 표기법 기본원칙을 모르더라도 한글단어, 문장, 문서를 문자열(string)로 입력받아 알고리즘화된 음운법칙을 적용하여 소리글자로 자동 변환 후 현행 정부 표준안인 국어 로마자 표기법 테이블에서 대응 글자를 참조하여 기계화 코드 변환이 가능토록 설계하였으며, 예외어 처리, 화면색상 및 풀다운 팝업 메뉴 방식을 지원, 마우스 활용 방식을 채택, 사용자 편리성을 제공하였으며, 다양한 서체, 글꼴 확대 및 축소, 이단ㆍ혼합 인쇄기능 등을 고려 C언어를 이용하여 구현하였다.