• 한국정보과학회논문지:정보통신
• /
• 제28권3호
• /
• pp.435-446
• /
• 2001

본논문에서는 클라이언트-서버 환경에서 DQDB-SR 네트워크 대역폭을 모든 스테이션에게 공병하게 할당하기 위한 새로운 방식을 제안하였다. 제안한 방식은 클라이언트-서버 부하 패턴의 특성을 따르는 접근 임계값과 대역폭 빌림과 반환 방식을 사용하여 DQDB-SR에게 공평한 대역폭 제어 기능을 제공한다. 이를 구현하기 위해 DQDB-SR의 처리 용량을 최대로 하는 소거 노드의 위치와 접근 임계값을 구하였다. 제안한 방식이 과부하시 클라이언트-서버 부하 패턴에 대하여 네트워크 처리 능력을 저하시키지 않고 패킷 전송 성공률과 평균 패킷 전달 지연 시간에 있어 다른 공정성 제어 방식들 보다 우수하다는 것을 시뮬레이션 결과를 통하여 확인하였다.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제1권1호
• /
• pp.32-39
• /
• 2012

With the aid of genetic algorithm (GA), global optimization with multiple geometry parameters is feasible in the design of switched flux permanent magnet (SFPM) machines. To investigate the advantages of global optimization over individual optimization, which has been used extensively for the design of SFPM machines, a comparison between the two approaches is carried out for the case of fixed copper loss and volume. In the case of individual parameter optimization, the sequence in which the individual parameters are optimized is very important. In the global optimization a better design can always be achieved although the corresponding torque density is found to be only slightly better than that of individually optimized with correct design sequence. By using the obtained global optimization results, the performance in machines having two types of stator and rotor pole combinations, i.e. 12/10 and 12/14, are compared, and it is shown that higher torque is exhibited in the 12/14 SFPM machine. Finally, this paper also demonstrates that global optimization, with the restriction of equal pole width, magnet thickness and slot opening, can maximize the torque density without significantly sacrificing other performance, such as cogging torque and overload capability.

• Journal of Electrical Engineering and Technology
• /
• 제13권1호
• /
• pp.105-113
• /
• 2018

This paper proposes pre-analysis on planning of high-voltage direct current (HVDC) transmission system applied to Korea electric power grid. HVDC transmission system for interface lines has been considered as alternative solution for high-voltage AC transmission line in South Korea since constructing new high-voltage AC transmission lines is challenging due to political, environmental and social acceptance problems. However, the installation of HVDC transmission system as interface line in AC grid must be examined carefully. Thus, this paper suggests three scenarios to examine the influences of the installation of HVDC transmission system in AC grid. The power flow and contingency analyses are carried out for the proposed scenarios. Power reserves in metro area are also evaluated. And then the transient stability analysis focusing on special protection scheme (SPS) operations is analyzed when critical lines, which are HVDC lines or high voltage AC lines, are tripped. The latest generic model of HVDC system is considered for evaluating the impacts of the SPS operations for introducing HVDC system in the AC grid. The analyses of proposed scenarios are evaluated by electromechanical simulation.

• Journal of Power Electronics
• /
• 제17권6호
• /
• pp.1512-1522
• /
• 2017

Switched reluctance motor (SRM) is suitable for electric vehicle (EV) applications with the advantages of simple structure, good overload capability, and inherent fault-tolerance performance. The SRM dynamic simulation model is built based on torque, voltage, and flux linkage equations. The EV model is built on the basis of the analysis of forces acting on a vehicle. The entire speed range of the SRM drive is then divided into constant torque and constant power areas. The command torque of the motor drive system is given according to the accelerator pedal coefficient and motor operation areas. A novel adaptive variable angle control is proposed to avoid the switching chattering between the current chopping control and angle position control modes in SRM drives for EV applications. Finally, simulation analysis and experimental results are conducted to verify the accuracy of the proposed simulation model and control strategy.

• 드라이브 ㆍ 컨트롤
• /
• 제18권1호
• /
• pp.9-16
• /
• 2021

Overloaded vehicles increase the maintenance cost of road structures, and they are a major factor in causing damage to the roads and bridges. In addition, overloaded vehicles compromise the braking capability of the vehicle; thus, threatening the safety of the driver. In order to prevent overloading of vehicles, the government is cracking down on the roads by using a device that measures the weight of vehicles. But this process is inconvenient because the place where the equipment is installed is far away from where the cargo is loaded. Due to the limitations of these fixed weighing devices, there is a growing need for technology that can monitor vehicle weight distribution and overload conditions in real time. In this work, we develop an onboard scale that can measure the load (weight) of trucks in real time. The onboard scale consists of high sensors, a signal processing unit, and a display, and it measures the load using height-displacement of the vehicle's leaf spring suspension.

• 정보보호학회논문지
• /
• 제14권5호
• /
• pp.153-164
• /
• 2004

온라인 게임과 같이 대규모로 데이터를 주고받는 클라이언트-서버 구조의 서비스에서 정보 보호를 위해 패킷을 암호화하면 암호화로 인해 서버에 과도한 부하가 유발되고 서비스에 심각한 문제가 생길 수 있다. 따라서 데이터의 보안 요구에 맞게 보다 효율적인 암호화 기법을 사용하여 암호화 부하를 되도록이면 줄이는 것이 필요하다. 본 논문에서는 암호화로 인한 부하를 줄이는 방법으로 복수의 암호 알고리즘을 이용하여 데이터의 보안 요구에 따라 암호화 체계를 달리하는 패킷 암호화 기법을 제안한다. 이러한 기법은 중요도가 서로 다른 다양한 종류의 데이터들이 끊임없이 전송되는 클라이언트-서버 구조의 인터넷 서비스에서 잘 적용될 수 있다. 실험을 통하여 본 논문에서 제안한 방법의 효율성을 정량적으로 검증한다.

• International Journal of Computer Science & Network Security
• /
• 제23권9호
• /
• pp.65-70
• /
• 2023

The "information roadway" will give us an impact of new PC based assignments and administrations, yet the unusualness of this new condition will ask for another style of human-PC association, where the PC transforms into a sharp, dynamic and customized partner. Interface administrators are PC programs that use Artificial Intelligence frameworks to give dynamic help to a customer with PC based errands. Operators drastically change the present client encounter, through the similitude that a specialist can go about as an individual collaborator. The operator procures its capability by gaining from the client and from specialists helping different clients. A couple of model administrators have been gathered using this methodology, including authorities that give customized help with meeting planning, electronic mail taking care of, Smart Personal Assistant and choice of diversion. Operators help clients in a scope of various ways: they perform assignments for the client's sake; they can prepare or educate the client, they enable diverse clients to work together and they screen occasions and methods.

• Smart Structures and Systems
• /
• 제32권3호
• /
• pp.179-193
• /
• 2023

This study explores an alternative to the existing centralized process for data anomaly detection in modern Internet of Things (IoT)-based structural health monitoring (SHM) systems. An edge intelligence framework is proposed for the early detection and classification of various data anomalies facilitating quality enhancement of acquired data before transmitting to a central system. State-of-the-art deep neural network pruning techniques are investigated and compared aiming to significantly reduce the network size so that it can run efficiently on resource-constrained edge devices such as wireless smart sensors. Further, depthwise separable convolution (DSC) is invoked, the integration of which with advanced structural pruning methods exhibited superior compression capability. Last but not least, quantization-aware training (QAT) is adopted for faster processing and lower memory and power consumption. The proposed edge intelligence framework will eventually lead to reduced network overload and latency. This will enable intelligent self-adaptation strategies to be employed to timely deal with a faulty sensor, minimizing the wasteful use of power, memory, and other resources in wireless smart sensors, increasing efficiency, and reducing maintenance costs for modern smart SHM systems. This study presents a theoretical foundation for the proposed framework, the validation of which through actual field trials is a scope for future work.

• 디지털콘텐츠학회 논문지
• /
• 제15권5호
• /
• pp.651-661
• /
• 2014

TV 플랫폼에서 원하는 콘텐츠를 찾기 위한 복잡성은 나날이 증가하고 있다. 컴퓨터 영역에서 이루어진 콘텐츠 관리를 위한 연구들을 참고해 TV에 적용할 수 있는 시사점을 도출하고, 이를 토대로 콘텐츠 검색과 선택을 도울 수 있는 방안을 제안한다. 컴퓨터 상의 정보는 대부분 현실 공간을 모사하는 공간적 은유(Spatial Metaphor)를 적용해 표현되고, 이는 사용자의 정보 확인 및 재인에 긍정적인 영향을 미친다. 제안된 정보 공간은 채널, 콘텐츠의 종류에 따른 분류와 시간 속성에 따른 분류를 포함한다. 시청자는 정보 공간 내에서 공간적 단서에 따라 콘텐츠 간의 관련성을 추론하여 선택할 수 있고, 시간적 순서에 따라 콘텐츠를 탐색할 수 있다. 내재된 능력을 활용하여 추가적인 인지적 부담을 최소화하는 방안을 제안하였고, 본 연구의 결과는 영상콘텐츠 기반의 다양한 서비스에 적용될 수 있을 것으로 기대된다.

• Advances in aircraft and spacecraft science
• /
• 제6권2호
• /
• pp.117-144
• /
• 2019

High Altitude and Long Endurance (HALE) aircraft are capable of providing intelligence, surveillance and reconnaissance (ISR) capabilities over vast geographic areas when equipped with advanced sensor packages. As their use becomes more widespread, the demand for additional range, endurance and payload capability will increase and designers are exploring non-conventional configurations to meet the increasing demands. One such configuration is the joined-wing concept. A joined-wing aircraft is one that typically connects a front and aft wings in a diamond shaped planform. One such example is the Boeing SensorCraft configuration. While the joined-wing configuration offers potential benefits regarding aerodynamic efficiency, structural weight, and sensing capabilities, structural design requires careful consideration of elastic buckling resulting from the aft wing supporting, in compression, part of the forward wing structural loading. It has been shown already that this is a nonlinear phenomenon, involving geometric nonlinearities and follower forces that tend to flatten the entire configuration, leading to structural overload due to the loss of the aft wing's ability to support the forward wing load. Severe gusts are likely to be the critical design condition, with flight control system interaction in the form of Gust Load Alleviation (GLA) playing a key role in minimizing the structural loads. The University of Victoria Center for Aerospace Research (UVic-CfAR) has built a 3-meter span scaled and flexible wing UAV based on the Boeing SensorCraft design. The goal is to validate the nonlinear structural behavior in flight. The main objective of this research work is to perform Ground Vibration Tests (GVT) to characterize the dynamic properties of the scaled flight vehicle. Results from the experimental tests are used to characterize the modal dynamics of the aircraft, and to validate the numerical models. The GVT results are an important step towards a safe flight test program.