• 한국유체기계학회 논문집
• /
• 제2권2호
• /
• pp.46-56
• /
• 1999

This study is on the performance prediction and design of a sirocco fan. Slip coefficient is very important factor for the performance analysis of a centrifugal-type fan. Because generally used slip coefficient equations of backward curved centrifugal fan are not appropriate for forward curved sirocco fan, in this study a proper slip coefficient equation for a sirocco fan is suggested. Using this equation performance prediction program for sirocco fan is composed of and also included the total noise prediction that include the turbulent noise at the fan inlet and boundary layer noise. A comparison between the values obtained from performance prediction program and experimental values shows that the program predicts the sirocco fan performance in a practical rate.

• 경영과학
• /
• 제29권1호
• /
• pp.115-129
• /
• 2012

Service Encounter employees play a crucial role in service delivery and building relationships with customers and their attitudes and behaviors towards customers determine customers' perceived service quality and satisfaction. Past research indicates that TQM managerial practices are a critical determinant of employee's attitude and performance in the workplace. Therefore, this study investigates a model examining the relationship among TQM, employees' attitude and service performance in a hospital. Our measurement results were acceptable in terms of reliability and validity. The statistical testing shows significance on the positive relationship in the sequential order of TQM, employee's attitude and service performance. In conclusion, the theoretical and practical implications of this study were discussed, along with its limitations.

• 한국경영과학회지
• /
• 제33권1호
• /
• pp.149-168
• /
• 2008

Many organizations have introduced information technology (IT) as an innovation to gain competitive advantages as business environments have become increasingly complex and rapidly changing. Despite the large investment of IT, there have been mixed results about whether IT creates business values. Considering that IT assimilation may play an important role in explaining IT productivity paradox, this study examines the formation of IT assimilation and its effect on the organizational performance. To do so, this study suggests a research model based on Innovation Diffusion Theory by incorporating organization system, communication channel, change acceptability, and innovation factors, and then attempts to empirically explore the role of IT assimilation for enhanced organizational performance using data collected at the organizational level. Structural equation analysis using AMOS provides significant support for part of proposed relationships. Specifically, we have found encouraging results on the role of IT assimilation by identifying its mediating effect on the organizational performance. Theoretical and practical implications of the findings are discussed accordingly.

• International Journal of Control, Automation, and Systems
• /
• 제5권5호
• /
• pp.584-593
• /
• 2007

BACnet is a standard data communication protocol especially designed for building automation and control networks. BACnet uses the Master-Slave/Token-Passing (MS/TP) protocol as one of its field-level networks. In this study, the performance of the BACnet MS/TP protocol is evaluated using an experimental model. The network performance is investigated and evaluated in terms of token rotation time and round trip time. The experimental results show that the performance of the MS/TP network is heavily influenced by the network traffic load, the assignment of MS/TP node address and the network configuration parameter called $N_{max_info-frames}$. Based on the experimental results, simple practical designing guidelines for BACnet MS/TP network systems are also proposed.

• Journal of Information Technology Applications and Management
• /
• 제22권1호
• /
• pp.109-130
• /
• 2015

This study aims to provide the results of a case study, based on the action research approach, in which an user-oriented management system for enterprise information systems operational performance is successful developed and applied. This study performs the research and summarizes the results by adopting 5-step approach of action research, i.e., diagnosing, action planning, action taking, evaluating and specifying learning. The most important lessons learned from the study include (1) operation performance measures should be established to be shared by the management and users; (2) evaluation and improvement activities should be performed continually; and (3) formula to calculate the measure should be evolved so that improvement initiatives can be identified. The results of the study are expected to provide the companies intending to develop a management system for enterprise information systems operational performance with the practical and useful information. In addition, it is expected to suggest the research results that can be utilized as a basis for future research in this area.

• 한국세라믹학회지
• /
• 제47권1호
• /
• pp.1-7
• /
• 2010

Solid oxide fuel cells (SOFCs) have been under development for a variety of power generation applications. Power system sizes considered range from small watt-size units (e.g., 50-W portable devices) to very large multi-megawatt systems (e.g., 500-MW base load power plants). Because of the reversibility of its operation, the SOFC has also been developed to operate under reverse or electrolysis mode for hydrogen production from steam (In this case, the cell is referred to as solid oxide electrolysis cell or SOEC.). Potential applications for the SOEC include on-site and large-scale hydrogen production. One critical requirement for practical uses of these systems is long-term performance stability under specified operating conditions. Intrinsic material properties and operating environments can have significant effects on cell performance stability, thus performance degradation rate. This paper discusses potential applications of the SOFC/SOEC, technological status and current research and development (R&D) direction, and certain aspects of long-term performance degradation in the operation of SOFCs/SOECs for power generation/hydrogen production.

• 한국해양공학회지
• /
• 제16권4호
• /
• pp.61-69
• /
• 2002

In the actual control systems, there exist many kinds of restrictions or nonlinearities. However, due to the nonlinearities in actuators and sensors, the designed controller may not be applicable in some practical situations. One such nonlinearity is amplitude saturation in actuators. Although sometimes it may be ignored, in other cases failure to consider actuator saturation may severely degrade closed-loop system performance and even lead to instability. On the other hand, limiting the controller gain to avoid saturation sacrifices control effort and may lead to loss of performance. Consequently, in some cases, the actuator saturation must be explicitly taken into account to ensure desired performance. However, in this paper, an anti-windup control system design method is introduced to suppress the windup due to the amplitude saturation of the actuator. The proposed control system has very simple design process and guarantees the good control performance. The validity of the proposed control system will be shown by comparing with the results of a reported paper.

• 한국해양공학회지
• /
• 제21권5호
• /
• pp.9-17
• /
• 2007

This paper deals with the design and analysis of a 250kW class impulse turbine for wave energy conversion. Numerical analysis was performed using FLUENT. The size and the performance of a turbine required to provide a certain power can be estimated using a series of performance charts built through the present study. Temporal and spatial variations of flaw fields were also considered and compared with those of uniform inflow. It was concluded that a simple steady-flow analysis using performance charts still provided a practical and useful way to predict the design and performance of turbines.

• 대한기계학회논문집A
• /
• 제33권12호
• /
• pp.1449-1454
• /
• 2009

The performance variation of a multibody system is affected by a variation of various design variables of the system. And the effects of design variable variations on the performance variation must be considered in design of a multibody system. Accordingly, a variation analysis of a multibody system needs to be conducted in design of a multibody system. For a variation analysis of a performance, population mean and variance which are called statistical parameters of design variables are needed. However, an evaluation of statistical parameters of design variables is impossible in many practical cases. Therefore, an estimation of statistical parameters of the performance based on sample mean and variance which are called statistic of design variables is needed. In this paper, the variation analysis method for a multibody system based on design variable samples was proposed. And, using the proposed method, a variation analysis of the vehicle ride comfort based on sample statistic of design variables was conducted.

• 한국소음진동공학회논문집
• /
• 제21권4호
• /
• pp.352-356
• /
• 2011

The isolation performance of a linear vibration isolator is limited to the ratio of stiffness to mass it supports. The stiffness of the isolator must be large enough to hold the weight. This results in the deterioration of the isolation performance. Recently, to overcome this fundamental limitation, the HSLDS(high-static-low-dynamic-stiffness) magnetic vibration isolator was introduced and its isolation characteristic was investigated theoretically. In this paper, the isolation performance of the HSLDS magnetic isolator is examined experimentally. Considerable amount of experiments are performed by carefully considering nonlinear characteristics. The experimental results verify the practical usability promisingly and agree with the theoretical studies, i.e. its performance is largely dependent on the key design parameter.