• Journal of Power System Engineering
• /
• v.7 no.4
• /
• pp.19-24
• /
• 2003

Exhaust brake system for Diesel engines is composed of gate valve, pneumatic cylinder and exhaust brake valve with on-off solenoid. Exhaust brake valve which is core component of exhaust brake system should have characteristics such as high reliability and long life. In this paper. exhaust brake valve with on-off solenoid which is used for vehicle brake system was studied. For the performance evaluation of on-off solenoid, electromagnetic characteristics and dynamic characteristics are analyzed. As a basic study for the performance improvement of exhaust brake system, pneumatic circuit and pneumatic valve with on-off solenoid were suggested and the performance of the pneumatic valve was evaluated through tests.

• Proceedings of the Korea Inteligent Information System Society Conference
• /
• 2007.05a
• /
• pp.218-225
• /
• 2007

Recommendation system is one way of implementing personalized service. The collaborative filtering is one of the major techniques that have been employed for recommendation systems. It has proven its effectiveness in the recommendation systems for such domain as motion picture or music. However, it has some limitations, i.e., sparsity and scalability. In this research, as one way of overcoming such limitations, we proposed the stepwise collaborative filtering method. To show the practicality of our proposed method, we designed and implemented a movie recommendation system which we shall call Step_CF, and its performance was evaluated using MovieLens data. The performance of Step_CF was better than that of Basic_CF that was implemented using the original collaborative filtering method.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.39 no.4
• /
• pp.19-31
• /
• 2014

We study parallel processing techniques for the R programming language of high performance computing technology. In this study, we used massively parallel computing system which has 25,408 cpu cores. We conducted a performance evaluation of a distributed memory system using MPI and of a the shared memory system using OpenMP. Our findings are summarized as follows. First, For some particular algorithms, parallel processing is about 150 times faster than serial processing in R. Second, the distributed memory system gets faster as the number of nodes increases while shared memory system is limited in the improvement of performance, due to the limit of the number of cpus in a single system.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.10a
• /
• pp.139-144
• /
• 1995

It is the aim of this study to introduce the performance and application of new repair system for the exterior wall by durability failure caused seasand especially. The elementary performance of this repair system is as follows (1)All the layer in the repair are cement based, same with the mother conrete (2)this repair system use SBR admixture (3)This cement and mortar powder for this repair system are premixed and ready to use just adding admixture at the job site.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.1
• /
• pp.97-103
• /
• 2002

In the determination of control laws of semi-active suspension system, optimal control theory is applied, which used in the design of fully active suspension system and in the performance index sense. Optimal semi-active control laws are designed, and the computer program is developed fur estimation of performance In the time and frequency domain. It is certified that in the semi-active control system, it is desirable to minimize the spring constant and damping coefficient as possible in the given constraints. The effect of performance improvement which is almost equal to fully active type is obtained.

• Journal of Power System Engineering
• /
• v.5 no.4
• /
• pp.90-96
• /
• 2001

In this study, a robust controller to control pressure in a pneumatic pressure vessel considering dynamic characteristics of pneumatic transmission line is proposed. Dynamic characteristics of transmission line using compressible fluid is changed by the flowing states of the fluid. So, if the fixed gain controller is designed based on a fixed model, the performance of the control system could be destabilized or degraded. The controller designed in this study is composed of two parts. The one is to reject modelling error based on the disturbance observer, the other is to obtain the control performance. The control results with the designed controller show that the robustness of the control system is achieved regardless of the change of the model of the transmission line. Therefore, the designed controller can be utilized for the performance improvement of the pressure control system using compressible fluid such as air and gas

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.7
• /
• pp.650-658
• /
• 2012

This paper proposes a high performance position controller for a driving system using a time optimal controller which has been widely used to control driving systems to achieve desired reference position or velocity in a minimum response time. The main purpose of this research lies in an improvement of transient response performance rather than that of steady-state response in comparison with other control strategies. In order to refine the scheme of time optimal control, Lyapunov stability proofs are incorporated in a controller of standard second order system model. This scheme is applied to the control of a driving system. In view of the simulation and experiment results, the standard second order system model exhibits better minimum-time control performance and robustness than double integral system model does.

• Proceedings of the Safety Management and Science Conference
• /
• 2006.11a
• /
• pp.287-292
• /
• 2006

Reducing the logistic cost may be accomplished by numbers of logistic management methods, but the most fundamental and essential one is the accomplishment of the consistent reverse logistics system that is the core of worker performance system, and the purpose of consistent reverse system is the treatment of logistic functions such as transportation, storage and unloading with consistent logistics, and increasing the turnover ratio is required for the improvement of the system. As the turnover ratios is increased, this paper make reverse worker performance evaluation system with lifetime value include of weight variables.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.11
• /
• pp.81-88
• /
• 1999

A conventional quarter-car suspension system is a single input system with one actuator. Thus, the performance enhancement for ride quality could be limited. In this paper, we propose a novel automotive suspension system for a quarter-car with two independent actuators to improve the control performance. The left eigenstructure assignment method for multi-variable systems has been applied to the proposed novel quarter-car model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2000.05a
• /
• pp.183-187
• /
• 2000

In this paper, the performance of DS-CDMA system and FH-CDMA system has been comparision analyzed in a channel environment which is characterized by Multi-User environment and Rayleigh fading environment. The techniques of improvement of the performance has been comperision analysis evaluated when adopting MRC diversity techniques. In same condition, We are analyzed the BER(Bit Error Rate) as increase Use's number due to comparing performance of two systems by Same communication band(300KHz), jamming signal(JSR) 10∼20dB, user data-rate 300bps. In the result, the performance of DS and FH systems in multiuser and Rayleigh fading environment is improved performance when adopting MRC diversity techniques. Especially DS system has been improved performance about 9.5 times than FH system when adopting MRC diversity techniques.