• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1752-1758
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• 2018

In a low-voltage distribution system, the molded case circuit breaker (MCCB) is a widely used device to protect loads by interrupting over-current; however the hot gas generated from the arc discharge in the interrupting process depletes the dielectric recovery strength between electrodes and leads to re-ignition after current-zero. Even though the circuit breaker is ordinarily tripped and successfully interrupts the over-current, the re-ignition causes the over-current to flow to the load again, which carries over the failure interruption. Therefore, it is necessary to understand the dielectric recovery process and the dielectric recovery voltage of the MCCB. To determine these characteristics, a measuring system comprised of the experimental circuit and source is implemented to apply controllable recovery voltage and over-current. By changing the controllable recovery voltage, in this work, re-ignition is driven repeatedly to obtain the dielectric recovery voltage V-t curve, which is used to analyze the dielectric recovery strength of the MCCB. A measuring system and an evaluation technique for the dielectric recovery strength of the MCCB are described. By using this system and method, the measurement to find out the dielectric recovery characteristics after current-zero for ready-made products is done and it is confirmed that which internal structure of the MCCB affects the dielectric recovery characteristics.

• The Journal of Society for e-Business Studies
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• v.7 no.1
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• pp.167-186
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• 2002

The encryption of a file on a PC before saving can maintain security of the file. However, if the key for the encrypted file is lost or damaged, the encrypted file can not be decrypted, resulting in serious economical loss to the user or the user group. In order to minimize the economical loss a secure and reliable key recovery technology is required. Presented in this paper is the development and evaluation of PKRS (PC based Key Recovery System) which supports encryption and decryption of file and recovery of the encrypted file in emergency. The encapsulating method, which attaches key recovery information to encrypted file, is applied to the PKRS. In addition, the PKRS is developed and evaluated according to the requirements of Requirements for Key Recovery Products proposed by NIST and requirements of Common Criteria 2.0 to prove the safety and reliability of the information security system. This system is applicable to a PC and can be further extended to internet or intranet environment information system where in encryption and recovery of file is possible.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.12
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• pp.1302-1312
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• 2008

Relaxed Static Stability(RSS) has been applied to improve flight performance of modern version supersonic jet fighters. Flight control systems are necessary to stabilize an unstable aircraft and to provide adequate handling qualities. Also, flight control systems of modern aircraft employ many safety measure to cope with emergency situations such as a pilot unknown attitude flight conditions of an aircraft in night flight-testing. This situation is dangerous because the aircraft can lose if the pilot not take recognizance of situation. The system called the "Pilot Activated Recovery System" or PARS, provided a pilot initiated automatic maneuver capable of an aircraft recoveries in situations of unusual attitudes, speed and altitude. This paper addresses the concept of PARS with AARS(Automatic Attitude Recovery System), ATCS(Automatic Thrust Control System) and MARES(Minimum Altitude Recovery Estimation System), and this control law is designed by nonlinear control law design process based on model of supersonic jet trainer. And, this control law is verified by real-time pilot evaluation using an HQS(Handling Quality Simulator). The result of evaluation reveals that the these systems support recovery of an aircraft unusual attitude and speed, and improve a safety of an aircraft.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.198-205
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• 2005

Reduction of labor hour for cleaning up of the used abrasives after blasting. is attempted by improving the efficiency of abrasive recovery process in the protective coating of ship's block, For this purpose, the theoretical background for pneumatic transport technology in the abrasive recovery system as well as experimental evaluation on the effect of design parameters such as flow pattern, saltation velocity and pressure drop on the efficiency of the abrasive recovery system are employed . By optimizing the operating parameters such as the length and diameter of the suction hose, specification of recovery device and recovery mouth, a new method which can dramatically increase the efficiency of abrasive recovery system, is proposed.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.411-417
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• 2024

In the event of a disaster, it is essential to establish a disaster recovery plan and disaster recovery system to minimize disruption to major IT infrastructure and provide continuous business services. In the process of building a disaster recovery system, data replication is a key element of data recovery to provide uninterrupted and continuous business services in the event of a disaster. The data replication method can be determined depending on the system configuration environment and disaster recovery goal level. In this paper, we present a method for determining a data replication method suitable for the configuration environment and disaster recovery target level when building a disaster recovery system. In addition, the replication method decision procedure is applied to build a disaster recovery system and analyze the construction results. After establishing the disaster recovery system, a test was conducted to determine whether the service was transferred to the disaster recovery center in a disaster situation and normal service was provided, and the results were analyzed. As a result, it was possible to systematically select the optimal data replication method during the disaster recovery system construction phase. The established disaster recovery system has an RTO of 3.7 hours for service conversion to the disaster recovery center to provide continuous business services, and the disaster recovery level, which was Tier 2, has been improved to the target level within 4 hours of RTO and RPO=0.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.10 no.1
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• pp.83-93
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• 2006

This paper introduces rule-based reasoning (RBR) based self-recovery system for network fault in ubiquitous computing. This system is fault management system for fault recovery of rule-based for self-recovery in ubiquitous computing environment. We proposed rules of network fault recovery applied the system as a distinguished reason of network fault. And, in this paper, the network fault self-recovery system proved the rules that applied each situatpion through the simulation.

• Journal of Information Technology Services
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• v.10 no.4
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• pp.83-101
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• 2011

Since most of companies these days are utilizing the Information system actively, Information System is the most important factor which should be recovered in terms of Business Continuity. However, a lot of enterprises have been outsourcing their Disaster Recovery Center. Therefore, it is highly possible that the information system can not work well and result in the discontinuity of business when any trouble arises because of seperated plan of Business Continuity and Disaster Recovery. The study draws critical success factors for successful disaster recovery through researches of 42 documents. Then, factors are reviewed through interviews with consultants, experts of Business Continuity Plan and the information system officers of domestic banks. Domestic companies can make use of the study when they develop or renew Disaster Recovery Plan or Information System in terms of Business continuity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.3
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• pp.240-246
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• 2012

The supply and use of exhaust heat recovery ventilation system as effective energy saving equipment has been increasing steadily. The exhaust heat recovery ventilation system can be installed at ceiling of balcony or emergency space. However, ventilation system can not be installed at emergency space because where have to remain as empty space by law. Therefore, the proper installation space of ventilation system is needed. In this study, to install heat recovery ventilation system in the light weight wall, thickness of heat exchanger was assembled below 140 mm. One or two paper heat exchangers were installed in the ventilation system. The efficiency of heat recovery was analyzed through performance experiment on case of cooling and heating mode.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.240-248
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• 2009

Modem version of supersonic jet fighter aircraft must have been guaranteed appropriate controllability and stability in HAoA(High Angle of Attack). The HAoA flight control law have two parts, one is control law of departure prevention and the other is control law of departure recovery support. The control laws of departure prevention for advanced jet trainer consist of HAoA limiter, roll command limiter and rudder fader. The control laws of departure recovery support are consist of yaw-rate limiter and MPO(Manual Pitch Override) mode. The guideline of pitch rocking using MPO mode is simple, but operating skill of pitch rocking is very difficult by the pilot with inexperience of departure situation. Therefore, automatic deep stall recovery system is necessary. The system called the "Automatic Pitch Rocker System" or APRS, provided a pilot initiated automatic maneuver capable of an aircraft recoveries in situations of deep stall, speed and altitude. This paper addresses the design and validation for APRS to recovery of an deep stall without manual pitch rocking by the pilot. Also, this system is designed to recovery of speed, attitude and altitude after deep stall recovery using ATCS (Automatic Thrust Control System) and autopilot. Finally, this system is verified by real-time pilot evaluation using HQS (Handling Quality Simulator).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.685-692
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• 2008

In this paper, we propose a timing recovery loop for Inmarsat mini-m system downlink receiver. Inmarsat mini-m system requires a timing recovery loop which is robust in frequency offset and has fast acquisition because Inmarsat mini-m system specification requires frequency tolerance is required of ${\pm}924$ Hz (signal bandwidth: 2.4 kHz) and acquisition time of UW (Unique Word) signal duration (15ms).Therefore, we propose a timing recovery loop which is suitable for Inmarsat mini-m system. The proposed timing recovery loop adopted noncoherent UW detector and differential ELD which applied differential UW signal for stability and fast acquisition in frequency offset environment. Simulation results show that the proposed timing recovery loop has stable operation and fast acquisition in frequency offset environment for the system.