• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.4
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• pp.15-20
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• 2007

All of the hydraulic spool valves adopt radially grooved spools to avoid hydraulic locking. In this paper, a commercial computational fluid dynamics (CFD) code, FLUENT is used to investigate the accurate Poiseuille flow characteristics inside single groove. The stream lines, velocity and pressure distributions are obtained for various groove widths, depths and shapes. The stream lines are highly affected by groove shape and there occurred large vortexes inside groove beyond a certain ratio of groove width to depth. Especially the U shaped groove restrains the occurrence of vortex. Therefore the numerical method adopted in this paper can be use in optimum designing of multi-grooved hydraulic spool valves.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1334-1340
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• 2003

In this paper, We have proposed an Heterodyne technique to generate millimeter-wave signal. Microwave signals in cellular broadband mobile communication networks and distributed networks can favorably be generated and distributed by optical techniques. In principle, these techniques have already been investigated for optical control of phase- array antennas, characterization of photo-detector and phase locking of millimeter-wave oscillators and now being applied to wireless communications. The generation and transmission of millimeter-wave radio signals by optical means is of interest for future pico-cell broadband mobile communication system, especially for systems operating at frequencies of 300Hz.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.170.3-170
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• 2001

Antilock brake system(ABS) prevent the wheels of road vehicle from locking up and skidding so that the braking force is from static friction instead of kinetic friction. Therefore ABS helps drivers maintain steering control during breaking situation particularly at an emergency stopping situation. So when trying to stop the road vehicle it is best to have the most friction possible for faster deceleration ABS keep the wheels turning which means there is more friction between the tires of vehicles and the road surface. Because of this advantage, ABS are now a commonly installed feature for passenger's safety in road vehicles. In this study, hydraulic system of ABS of vehicle is composed of 3port-2position solenoid valve. In order to minimize ...

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.4
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• pp.156-163
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• 1996

The brakes are the most important safety-critical accident avoidance components of a motor vehicle. They must perform safely under a variety of operating conditions and must have enough strength not to fail during the life of a vehicle. Recently, anti-lock brake systems are used on more and more passenger cars. The ABS brakes modulate brake line pressure to prevent brakes from locking during braking. In this study, finite element analysis, material test for FCD45, measurement of stress and cumulative fatigue damage analysis were performed to evaluate fatigue damage of the caliper housing under ABS mode.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.917-920
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• 2006

It is possible to make a practical application for many services by using Home Networking. It's brings much improve the quality of our life. Remote control communication should be made by Home Network but present networks are generally using wireless Internet. But, this method don't use exist home and not install wireless internet. Because It need to many devices. Therefore, in this paper we implement gas valve remote control system using RPM(Radio Packet Modem). We can easily installing systems and operating. This system provide different solution for Home networking.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.229-230
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• 2007

It is possible to make a practical application for many services by using Home Networking. It's brings much improve the quality of our life. Remote control communication should be made by Home Network but present networks are generally using wireless Internet. But, this method don't use exist home and not install wireless internet. Because It need to many devices. Therefore, in this paper we implement gas valve remote control system using RPM(Radio Packet Modem). We can easily installing systems and operating. This system provide different solution for Home networking.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.304-306
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• 2016

In the recent years ransomware has become one of the most popular malware used by criminals. This particular type of malware is notorious for locking users' data or systems and unscrambling it only after the victims pay a fee. With more and more individuals, companies and public agencies being targeted and the ransom being as high as $17,000, the need for countermeasures against this kind of malware is greater than ever. This paper explores how the malware infects and encrypts its victims. Then, it suggests mitigation techniques based on how the ransomware spreads, making special emphasis on countermeasures in order to protect end-users.

• Smart Structures and Systems
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• v.20 no.6
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• pp.729-737
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• 2017

Piezoelectric composite laminates are a powerful material system that offers vast options to improve structural behavior. Successful design of piezoelectric adaptive structures and testing of control laws call for highly accurate, reliable and numerically efficient numerical tools. This paper puts focus onto linear and geometrically nonlinear static and dynamic analysis of smart structures made of such a material system. For this purpose, highly efficient linear 3-node and 4-node finite shell elements are proposed. Both elements employ the Mindlin-Reissner kinematics. The shear locking effect is treated by the discrete shear gap (DSG) technique with the 3-node element and by the assumed natural strain (ANS) approach with the 4-node element. Geometrically nonlinear effects are considered using the co-rotational approach. Static and dynamic examples involving actuator and sensor function of piezoelectric layers are considered.

• Journal of KIISE:Software and Applications
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• v.26 no.2
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• pp.223-233
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• 1999

데이터베이스 공유 시스템(Database Sharing System : DSS) 은 고성능의 트랜잭션 처리를 위해 제안된 구조이다. DSS에서 고속의 통신망으로 연결된 노드들은 별도의 메모리와 운영체제, 그리고 DBMS를 가지며, 데이터베이스르 저장하고 있는 디스크는 모든 노드에 의해 공유된다. 빈번한 디스크 액세스를 피하기 위해 각 노드는 자신의 메모리 버퍼에 최근에 액세스한 페이지들을 캐싱한다. 본 논문에서는 레코드와 같은 미세 단위의 로킹을 지원하는 DSS에서 데이터베이스를 정확한 상태로 복구할 수 있는 회복 기법인 DRCP(Database Recovery using Cached Pages)를 제안한다. DRCP는 정상적으로 동작하고 있는 다른 노드에 캐싱된 페이지의 내용을 참조하여 회복 작업을 수행함으로써 디스크 액세스 수와 회복 과정에서 필요한 로그 스캔의 범위를 줄일 수 있고 , 그 결과 데이터베이스를 빨라 복구할 수 있다는 장점을 갖는다.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.7-9
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• 2012

2단계 잠금 규약은 데이터베이스에서 트랜잭션의 직렬성을 보장하는 방법이다. 분산 클라우드 시스템에는 분산된 노드들에 의한 합의 문제가 필연적으로 존재하여, 이는 분산 시스템에서 2단계 잠금을 비롯한 데이터베이스 이론의 적용을 어렵게 한다. 본 논문에서는 ZooKeeper를 이용하여 분산 클라우드 시스템에서 활용 가능한 2단계 잠금의 구현을 보이고, 이것이 트랜잭션의 직렬성을 보장함을 확인한다. 또한 분산시스템의 잠금 과정에서 발생할 수 있는 교착 상태 해결의 구현을 보인다.