• Smart Structures and Systems
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• 제19권6호
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• pp.587-599
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• 2017

This paper introduces an approach to the realization of an ICT-based bridge remote monitoring system that enables real-time monitoring and controlled adjustments for unexpected heavy loads and also for damaging earthquakes or typhoons. In this paper, an integrated bridge remote monitoring system called the "Intelligent Bridge", which consists of a stand-alone monitoring system (SMS) and a web-based Internet monitoring system(IMS), was developed for not only bridge maintenance but also as an application for a para-stressing bridge system. To verify the possibility of controlling the actual structural performance of an "Intelligent Bridge", a model 2-span continuous cable-stayed bridge with adjustable cables was constructed. The experimental results demonstrate that the implemented monitoring system supplies detailed and accurate information about bridge behaviour for further evaluation and diagnosis, and it also opens up prospects for future application of a web-based remote system to actually adjust in-service bridges under field conditions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.579-583
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• 1988

As the power facilities grow up, the optimal operation and the best maintenance of power plant can not be overestimated too much, which can enhance the plant availability and reliability much further. In this respect, fault diagnosis methodologies of dynamic system which is time-varing and strongly nonlinear have been studied. On of them is to use algorithm which is based on time-invariant, linear system, but this is not so nice a method for applying to power Plant. Therefore, the study on other techniques using Artificial Intelligence (AI) is under way. In this paper, the existing ways of fault detection are surveyed and their problems are also discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권5호
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• pp.2043-2060
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• 2020

Developed from Digital Multimedia Broadcasting (DMB), DMB+ changes the application focus fundamentally. The plus symbol "+" indicates that DMB+ is no longer for digital radio/videos, instead it works as a general data transmission technique. The merits of wireless transmission, broad coverage, high quality, information security and low building/maintenance cost make DMB+ suitable for a wide range of applications with numerous terminals and users, such as public information release, alarm and administration etc. The concept of DMB+ base station enables DMB+ to be used in building independent networks and for remote control and management, as well as for Industry 4.0. DMB+ will access into a new field that till now has been dominated by communication techniques, will open a huge commercial opportunity.

• 대한산업공학회지
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• 제40권1호
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• pp.34-42
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• 2014

SCADA and DCS that have performed automatic control and monitoring activities increase the productivity of enterprise in industries. In such systems, although their performance had been improved, there are still many deficiencies in predictive maintenance which can foresee the risk of any kinds of accidents. Because the data acquisition systems of main facilities are being distributed throughout the whole plant and therefore, integration of data obtained from the systems is very difficult. Accordingly, techniques that acquire meaningful information from the gathered data through realtime analysis still need to be improved. This paper introduces a developed facility monitoring system which can predict equipment failure and diagnose facility status through big data analysis to improve equipment efficiency and prevent safety accidents.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1175-1178
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• 2004

On-line partial discharge(PD) monitoring system has been developed to monitor in operating large motor stator insulations. This system makes use of remote diagnosis techniques for the evaluation of PD activity in the control center of thermal power plant. This system can be remotely accessed via a modem to build database, analyze status and interpret the pattern of PD activity. A personnel computer is generally connected to ten motors to continuous measurement of the PD activity. The test data can be easily interpreted by a maintenance staff. For assessing the condition of stator winding in motors, this system ensures a reliable measurement and accurate estimation. Capacitive couplers used for on-line PD measurement have been 80pF. The maximum PD magnitude(Qmax), PD pattern and normalized quantity number(NQN) were performed by this system.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.886-891
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• 2005

The frequent maintenance required on some asphalt concrete (AC) pavement sections has made reconstruction with Portland Cement Concrete Pavement (PCCP) a feasible alternative. However, many constructability issues need to be addressed in order to realize the full potential of this alternative. Accelerated paving encompasses three classes of activities: methods to accelerate the rate of strength gain, methods to minimize the construction time, and traffic control strategies to minimize user delay. Three major AC intersections with severe rutting problems were reconstructed with PCCP. The entire reconstruction of each intersection, including demolition of the AC pavement and its replacement with PCCP, took place over a period of three days, starting on Thursday evening and opening the intersection to the traffic on Sunday afternoon. This paper discusses the use of PCCP for accelerated reconstruction of major urban intersections with minimal user and traffic disruption, using innovative construction techniques and traffic management optimization principles and demonstrates that concrete pavements can be constructed efficiently and quickly.

• 정보보호학회논문지
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• 제31권6호
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• pp.1237-1246
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• 2021

본 논문은 AES 블록 암호에 OFB(Output Feedback) 모드를 적용한 ATM(Asynchronous Transfer Mode) 셀 보안에 관한 것이다. ATM 셀은 사용자 데이터 셀과 유지 보수 셀로 구분되며 각 셀의 크기는 53 옥텟이며 5 옥텟의 헤더와 48 옥텟의 페이로드로 구성되어 있다. ATM 셀의 암호화/복호화를 위해서는 셀의 경계를 감지해야 하는 데 이는 헤더 내의 HEC(Header Error Control)필드를 이용하여 가능하다. 셀의 경계를 감지한 후에는 사용자 셀만 암호화하기 위하여 PT(Payload Type)코드를 이용하여 페이로드의 종류를 감지한다. 본 논문에서는 ISO 9160의 요구사항을 만족하는 ATM 셀의 보안 방법을 제시하였다.

• 한국콘텐츠학회논문지
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• 제6권1호
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• pp.160-169
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• 2006

본 논문은 바이트코드(bytecode) 수준에서 프로그램 분석과 최적화를 위한 구조를 서술한다. 바이트코드 수준에서 분석을 수행하기 위해서는 우선 제어 흐름 그래프(CFG : Control Flow Graph)를 생성해야 한다. 바이트코드의 특성 때문에 기존의 제어 흐름 분석 기술을 바이트코드에 적합하게 확장해야 한다. CFG를 작성하기 위해 기본 블록을 생성하고 기본 블록간의 관계를 이용하여 최적화 과정에서 사용되는 각종 정보를 생성한다. 생성된 CFG는 자바 바이트코드의 이해와 유지보수를 위해 테스트되고, 데이터 흐름 분석과 의존성 분석과 같은 다른 분석을 위해서 사용된다. 본 논문에서는 바이트코드 수준의 제어 흐름 분석을 위해 CTOC(Classes To Optimized Classes)의 CTOC-BR(CTOC-Bytecode tRanslator)을 구현한다. CTOC는 자바 바이트코드의 최적화와 분석을 위해 현재 개발 중인 프레임 워크의 이름이고, CTOC에서 CTOC-BR은 스택 기반인 바이트코드의 최적화와 분석을 쉽게 하기 위해 트리 형태로 변환을 수행하는 도구이다.

• Geomechanics and Engineering
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• 제22권5호
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• pp.449-460
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• 2020

The double-lane arrangement model is frequently used in underground coal mines because it is beneficial to improve the mining efficiency of the working face. When the double-lane arrangement is used, the service time of the reserved roadway increases by twice, which causes several difficulties for the maintenance of the roadway. Given the severe non-uniform deformation of the reserved roadway in the Buertai Coal Mine, the stress distribution law in the mining area, the failure characteristics of roadway and the control effect of support resistance (SR) were systematically studied through on-site monitoring, FLAC 3D numerical simulation, mechanical model analysis. The research shows that the deformation and failure of the reserved roadway mainly manifested as asymmetrical roof sag and floor heave in the region behind the working face, and the roof dripping phenomenon occurred in the severe roof sag area. After the coal is mined out, the stress adjustment around goaf will happen to some extent. For example, the magnitude, direction, and confining pressure ratio of the principal stress at different positions will change. Under the influence of high-stress rotation, the plastic zone of the weak surrounding rock is expanded asymmetrically, which finally leads to the asymmetric failure of roadway. The existing roadway support has a limited effect on the control of the stress field and plastic zone, i.e., the anchor cable reinforcement cannot fully control the roadway deformation under given conditions. Based on obtained results, using roadway grouting and advanced hydraulic support during the secondary mining of the panel 22205 is proposed to ensure roadway safety. This study provides a reference for the stability control of roadway with similar geological conditions.

• 수산해양기술연구
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• 제60권1호
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• pp.71-79
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• 2024

In compliance with environmental regulations at sea and the introduction of unmanned autonomous ships, electric propulsion ships are garnering significant attention. Induction machines used as propulsion electric motor (PEM) have maintenance advantages, but speed control is very complicated and difficult. One of the most commonly used techniques for speed control is DTC (direct torque control). DTC is simple in the reference frame transformation and the stator flux calculation. Meanwhile, two-level and three-level voltage source inverters (VSI) are predominantly used. The three-level VSI has more flexibility in voltage space vector selection compared to the two-level VSI. In this paper, speed is controlled using the DTC method based on the specifications of the PEM. The speed controller employs a PI controller with anti-windup functionality. In addition, the characteristics of the two-level VSI and three-level VSI are compared under identical conditions. It was confirmed through simulation that proper control of speed and torque has been achieved. In particular, the torque ripple was small and control was possible with a low DC voltage at low speed in the three-level VSI. The study confirmed that the application of DTC, using a three-level VSI, contributes to enhancing the system's response performance.