• Journal of the Korea Convergence Society
• /
• v.1 no.1
• /
• pp.17-21
• /
• 2010

This paper proposes a mechanism for managing overload in real-time web service system. The many previous mechanisms manage overload with controlling web request. These mechanisms can control only new web request. They don't have any control existing tasks, especially periodic tasks. We design a controller that able to meet real-time performance with controlling even periodic tasks. A feedback control system is implemented applying the proposed mechanism. And we verified the stable operation of system.

• Nuclear Engineering and Technology
• /
• v.50 no.1
• /
• pp.80-87
• /
• 2018

Consideration is given to the possibility to use changes in buoyancy as a negative reactivity feedback mechanism during temperature transients in heavy liquid metal fast reactors. It is shown that by the proper use of heavy pellets in the fuel elements, fuel rods could be endowed with a passive self-ejection mechanism and then with a negative feedback. A first estimate of the feasibility of the mechanism is calculated by using a simplified geometry and model. If in addition, a neutron poison pellet is introduced at the bottom of the fuel, then when the fuel element is displaced upward by buoyancy force, the reactivity will be reduced not only by disassembly of the core but also by introducing the neutron poison from the bottom. The use of induced buoyancy opens up the possibility of introducing greater amounts of actinides into the core, as well as providing a palliative solution to the problem of positive coolant temperature reactivity coefficients that could be featured by the heavy liquid metal fast reactors.

• Proceedings of the Korean System Dynamics Society
• /
• 2004.08a
• /
• pp.109-128
• /
• 2004

The complexity of information and communication policy has been increasing due to its rapid changes and its expansions toward various fields. I used the2001, 2002 and 2003 White Papers on MIC(Ministry of Information and Communication Republic of Korea) as a reference and the Vensim PLE program to create a causal map. According to my analysis, no major feedback loop was found among the information and communication policies. Thus, it was impossible to conduct a causal map analysis on these policies. The causal map analysis is usually employed to understand a complex mechanism of entire policies by finding feedback loops among them. A lack of feedback loops makes it impossible to conduct the causal map analysis and means that the mechanism of such policies is even more complex to understand. The most important conclusion is that to consider feedback thought among the policies based on the systems thinking before making the policies.

• The KIPS Transactions:PartA
• /
• v.10A no.6
• /
• pp.615-626
• /
• 2003

This paper proposes a mechanism for managing overload Introduced by excessive web requests in real-time web service system. The many previous mechanisms statically manage the overload and thus the dynamic characteristics are not reflected. This paper proposes a mechanism that models system load based on control theory approach and includes its dynamic characteristics. We design a controller that is able to meet performance requirement. A feedback control system is implemented applying the proposed mechanism and the stable operation of system is verified through various simulation environments.

• Proceedings of the Korean Information Science Society Conference
• /
• 1998.10b
• /
• pp.544-546
• /
• 1998

소프트웨어 프로세스 모형은 실세계 소프트웨어 프로세스의 개념적인 표현이다. 소프트웨어 프로세스 모형들은 프로세스 프로그래밍 언어를 통해 추상화됨으로써 모형화 될 수 있으며, 프로세스 모형들을 자동으로 수행(enactment)하고, 이미 수행된 프로세스 모형들을 체계적으로 관리하는 수행지원시스템을 통해서 소프트웨어 생산물의 질적인 향상을 기대할 수 있다. 본 논문에서는 소프트웨어 프로세스의 수행 중에 발생할 수 있는 프로세스의 feedback을 지원하는 SimFlex 프로세스 프로그래밍 언어의 확장된 언어구조와 프로세스 수행지원 시스템인 SEED 엔진에서의 효과적인 feedback 지원 방법에 대하여 설명한다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.969-972
• /
• 2004

This paper describes the mechanism of parallel micro machine platform and its feedback control system for acquiring high accuracy. The parallel micro machine platform that has developed has 5x5x5 work-space and sub-micron accuracy. For the high accuracy, the feedback control system is important but errors in machining and assembling are inevitable. Kinematic calibration is important for this reason. In this paper, various error components are introduced and the effects of error component are analyzed.

• 제어로봇시스템학회:학술대회논문집
• /
• 2002.10a
• /
• pp.51.4-51
• /
• 2002

$\textbullet$ A noval haptic mouse system is developed for human computer interface. $\textbullet$ Five bar mechanism is adapted for 2 dof force feedback with virtual environment. $\textbullet$ Double prismatic joint type mechanism is adapted to reflect 1 dof grabbing force feedback. $\textbullet$ Cable driven mechansim is used for actuation to reduce backlash and endow backdrivability. $\textbullet$ Virtual wall perception experiment is conducted to obtain force specification for haptic mouse. $\textbullet$ Average mouse workspace is measured using magnetic position tracker.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.9
• /
• pp.1234-1240
• /
• 2002

A new feedback control law is proposed and tested for suppressing the vortex shedding from a circular cylinder in a uniform flow. The lift coefficient ( $C_{L}$) is employed as a feedback control signal and the control forcing is given by a rotational oscillation of the cylinder. The influence of the feedback transfer function on the $C_{L}$ reduction is examined. The main rationale of the feedback control is that a feedback control forcing is imposed at a phase which is located outside the range of lock-on. By applying the feedback control law, $C_{L}$ is reduced significantly. Furthermore, the reduction mechanism of $C_{L}$ is analyzed by showing the vortex formation modes with respect to the forcing phase.e.ase.e.

• Asia pacific journal of information systems
• /
• v.5 no.1
• /
• pp.164-185
• /
• 1995

A considerable number of empirical studies have been conducted into the impact of graphical presentation of information on decision making performance. Very limited attention has been, however, devoted to the role of graphs as a means of delivering feedback. This paper investigated this issue by varying the presentation formats of outcome feedback in time series forecasting contexts. It was found that overall feedback was not decision-effective. Even enlarged and more salient feedback was of little value to overcome the conservative behavior. The results doubted the efficacy of graphical feedback in the design of EIS/DSS. Feedback did not appear to be a simple mechanism and further research is required to investigate its cognitive processes.

• Journal of Internet Computing and Services
• /
• v.4 no.2
• /
• pp.39-45
• /
• 2003

Throughput response characteristics depending on the network bandwidth allocation is needed to be modeled to devise adaptive control mechanism to support QoS of the local network. In this study, we propose a dynamic system model that reveals the response characteristics of network. The adaptive traffic feedback control is applied to this model. And we simulate this system for optimization of adaptive control mechanism.