• Journal of Power System Engineering
• /
• v.20 no.5
• /
• pp.78-85
• /
• 2016

This paper considers the influence of internal heat exchangers to the efficiency of a refrigerating system using R170. These liquid-gas heat exchangers(internal or suction-line heat exchangers) can, in some cases, yield improved system performance while in other cases they degrade system performance. A steady state mathematical model is used to analysis the performance characteristics of refrigeration system with internal heat exchanger. The influence of operating conditions, such as the mass flowrate of R170, inner diameter tube and length of internal heat exchanger, to optimal dimensions of the heat exchanger is also analyzed in the paper. The main results were summarized as follows : the mass flowrate of R170, inner diameter tube and length of internal heat exchanger, and effectiveness have an effect on the cooling capacity, compressor work and RCI(Relative Capacity Index) of this system. Exception for the effect of inner diameter, the RCI of R170 with respect to refrigerant mass flowrate, the length and effectiveness of internal heat exchanger is about 2.1~3.3% higher than that of R13 at the same experimental conditions. With a thorough grasp of these effect, it is necessary to design the R170 compression refrigeration cycle using internal heat exchanger.

• Journal of Fisheries and Marine Sciences Education
• /
• v.28 no.4
• /
• pp.984-993
• /
• 2016

This study aims to analyze the aquaculture farmers awareness of aquafarm management system influenced by socio-economic, environmental, and other factors using ordered logit model focused on aquafarm resting system. The survey data were obtained from 94 aquaculture farmers in Gyeongsangnamdo and Jeollanamdo province as a cross sectional data in 2015. This paper estimates the impact of socio-economic, environmental, and other characteristics, such as region, working period, productivity, environmental condition of fishing field, expected effectiveness of the system, and subject of responsibility on fishing field management. Based on the result, lastly, it suggests some implications to promote aquaculture farmers perception and participation in aquafarm resting system. The main results are as follows; the aquaculture farmers consciousness of the system is not affected by working period, productivity, and environmental condition of fishing field. But it is influenced by region, expected effectiveness of the system, and subject of responsibility on fishing field management. While it has a positive relationship with expected effectiveness of the system, it has a negative relationship with object who has responsibility on fishing field management.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.23 no.4
• /
• pp.141-149
• /
• 1998

One of the difficulties in using the current Boolean-based information retrieval systems is that it is hard for a user, especially a novice, to formulate an effective Boolean query. One solution to this problem is to let the system formulate a query for a user from his relevance feedback documents in this research, an intelligent query reformulation mechanism based on ID3 is proposed and the sensitivity of its retrieval effectiveness, i.e., recall, precision, and E-measure, to various input settings is analyzed. The parameters in the input settings is the number of relevant documents. Experiments conducted on the test set of Medlars revealed that the effectiveness of the proposed system is in fact sensitive to the number of the initial relevant documents. The case with two or more initial relevant documents outperformed the case with one initial relevant document with statistical significances. It is our conclusion that formulation of an effective query in the proposed system requires at least two relevant documents in its initial input set.

• Proceedings of the KSME Conference
• /
• 2000.04b
• /
• pp.753-758
• /
• 2000

Heat engine and fluid machinery in the plant have to linked with various ducts network and the corresponding design have to be concerned about effectiveness and stability of system of plant. To optimum control and design system concerning stability, economization, operating effectiveness we have to exact analysis flow properties of a duct applying to fluid machinery, heat exchanger, cooling machine, air conditioning equipment. therefore, it is necessary to research the duct, heat transfer equipment, for increasing overall effectiveness of air conditioning system by suggesting basic data of the duct resulting from organic research. So we can contribute to technical development of the duct. In case of speeding up the flow rate of the duct, lots of wave velocity components are occurred the value of boundary layer resulting from developing the boundary layer at both walls of duct.

• Knowledge Management Research
• /
• v.6 no.2
• /
• pp.67-90
• /
• 2005

Attention has been focused recently on the concept of shared cognition which encompasses the notion that effective team members hold knowledge that is overlapping and complementary with teammates. This shared cognition is expected to improve team effectiveness. In contrast to the continued efforts in developing theoretical approach of shared cognition, empirical studies are meager. Thus, we conducted an empirical study to investigate the role of shared cognition on team effectiveness. This study classifies shared cognition into two types, team mental model and transactive memory system, by shared meaning. A total of 121 new product development teams in the IT industry were surveyed for the data collection. The results of analysis can be summarized as follows: first, team mental model has a positive influence on team performance, team innovative behavior and team learning effect. And the relation with team mental model and team performance is moderated by the similarity of knowledge structure among the expert. Second, transactive memory system has a positive influence on team performance, team innovative behavior and team learning effect.

• Journal of the Korea Society for Simulation
• /
• v.27 no.3
• /
• pp.89-97
• /
• 2018

In future warfare, most part of resources and their platforms would be replaced by unmanned system like UGV(Unmanned Ground Vehicle). They are also connected each other with communication network and it is called NCW(Network Centric Warfare) environment. Hence how to measure the effectiveness of UGV operated in NCW circumstance become an important issue. However, there are few research paper to deal with this kind of UGV effectiveness issue coupled with communication failure. In this paper, we proposed a new ABM process to measure the UGV effectiveness combined with communication success ratio based on terrain condition of the ground engagement. Additionally, we also provide the effectiveness analysis result when communication repeater is applied in case of communication failure.

• Journal of Engineering Education Research
• /
• v.27 no.3
• /
• pp.26-33
• /
• 2024

This study aimed to verify the learning effectiveness of students who took courses in the field of new and renewable energy, which have been operated within a convergence university system. To achieve this, data were collected from 1,228 students who participated in 34 courses jointly developed and conducted by seven universities as part of standard curriculum offerings. The study analyzed learning effectiveness (course satisfaction, transfer motivation, learning transfer, creativity-convergence competency) using Excel 2018 and SPSS 25.0. It also examined inter-university differences in learning effectiveness and identified factors influencing creativity-convergence competency. The main findings are as follows: (a) Course satisfaction (M= 4.20), transfer motivation (M=3.62), learning transfer (M= 4.06), and creativity-convergence competency (M=3.92) were generally high. (b) Analysis of learning effectiveness differences between universities showed no significant differences among universities A, B, C, D, and E. University F was lower compared to other universities, while University G was significantly higher than others. (c) Sex, grade, number of courses taken, course satisfaction, transfer motivation, and learning transfer had effect on creativity-convergence competency. The results of this study provided implications for promoting activities to attract students, expanding transfer opportunities, and ensuring student agency.

• Structural Engineering and Mechanics
• /
• v.89 no.4
• /
• pp.383-397
• /
• 2024

To improve the vibration control performance and applicability of traditional particle tuned mass damper (PTMD) and realize the significant characteristic of lightweight design, this study proposes a novel particle tuned mass inerter system (PTMIS) by introducing inerter system (IS) to the PTMD. In the study, the motion equation of single degree of freedom (SDOF) structure attached with PTMIS is established first, then the variation law of the system's vibration reduction performance (VRP) is discussed through parameter analysis, and it is compared with the PTMD to analyze its VRP advantages. Finally, its vibration reduction (VR) mechanism from the perspective of core control force and energy analysis is explored, and its cavity relative displacement from the application perspective is analyzed. The results show that the PTMIS can remarkably improve the vibration control effectiveness of the PTMD. The reason is that the inerter can store energy and transfer the energy to the cavity and particles, which further stimulates the interaction between the two parts, thereby improving the nonlinear energy consumption effectiveness. Also, the IS can amplify the damping element's energy dissipation efficiency. In addition, the PTMIS can effectively reduce the working stroke of the PTMD, and through the analysis of the lightweight characteristics of the PTMIS, it is found that its lightweight advantage can reach nearly 100%.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.8
• /
• pp.1394-1400
• /
• 2010

This paper introduces a newly improved Ultra-FRFET that has much better reverse recovery characteristic than that of the typical MOSFET and presents its effectiveness in the HV-BLU system of LCD TVs. The reverse recovery time, $T_{rr}$ of Ultra-FRFET is shorter than 40nsec and the peak value of reverse current, $i_{rr}$ is also much smaller compared to the typical MOSFET's, which are sufficient to prevent the MOSFET’s failures without additional FRDs and diodes in HV-BLU system with a half-bridge resonant inverter topology worked by PWM method. In order to verify the validity, the loss analysis and the implementation results in cases when both the conventional solution using typical MOSFETs with additional FRDs and a new solution using Ultra-FRFETs are applied to a HV-BLU of 40" LCD TV are presented. As a result, the effectiveness of Ultra-FRFET was verified and the results are presented in this paper.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.1 s.24
• /
• pp.24-32
• /
• 2006

This paper is to analyze the effectiveness of multistatic sonar network based on detection performance. The multistatic sonar network is a distributed detection system that places a source and multi-receivers apart. So it needs a detection technique that relates to decision rule and optimization of sonar system to improve the detection performance. For this we propose a data fusion procedure using Bayesian decision and optimal sensor arrangement by optimizing a bistatic sonar. Also, to analyze the detection performance effectively, we propose the environmental model that simulates a propagation loss and target strength suitable for multistatic sonar networks in real surroundings. The effectiveness analysis on the multistatic sonar network confirms itself as a promising tool for effective allocation of detection resources in multistatic sonar system.