• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.1
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• pp.9-18
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• 2007

There have been continuous efforts for automation of joint tracking system. This automation process is mainly used to do in root pass of gas metal arc welding in the field of heavy industry and shipbuilding etc. For automation, it is important using of vision sensor. Welding robot with vision sensor is used for weld seam tracking on welding fabrication. Recently, it is used to on post-weld inspection for weld quality evaluation. For real time seam tracking, it is very important role in vision process technique. Vision process is included in filtering and thinning, segmentation processing, feature extraction and recognition. In this paper, it has shown performance comparison results of seam tracking for real time root pass on gas metal arc welding. It can be concluded better segment splitting method than iterative averaging technique in the performance results of seam tracking.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.118-123
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• 2013

This paper presents performance comparison between concentrated winding and distributed winding of IPMSM (Interior Permanent Magnet Synchronous Motors) which is recently used for light-weight railway applications. Motors are designed on various schemes and analyzed by using FEM (Finite Element Method) instead of EMCNM (Equivalent Magnetic Circuit Network Method) in order to take into account saturation and non-linear magnetic property. The overall performance such as torque, torque ripple, losses, demagnetization, efficiency, power density and so on are investigated in detail at the rated and maximum operating speed. The results of the analysis found that both concentrated and distributed winding IPMSMs are promising candidates for high power railway traction motor.

• Structural Engineering and Mechanics
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• v.65 no.3
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• pp.251-261
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• 2018

Self-centering concentrically braced frames (SCCBFs) are emerging as high performance seismically resistant braced framing system, due to the capacity of withstanding strong earthquake attacks and promptly recovering after events. To get a further insight into the seismic performance of SCCBFs, systematical evaluations are currently conducted from the perspective of modal contributions. In this paper, the modal pushover analysis (MPA) approach is utilized to obtain the realistic seismic demands by summarizing the contribution of each single vibration mode. The MPA-based results are compared with the exact results from nonlinear response history analysis. The adopted SCCBFs originate from existing buckling-restrained braced frames (BRBF), which are also analyzed for purpose of comparison. In the analysis of these comparable framing systems, interested performance indices that closely relate to the structural damage degree include the interstory drift ratio, floor acceleration, and absorbed hysteretic energy. The study shows that the MPA approach produces acceptable predictions in comparison to the exact results for SCCBFs. In addition, the high-modes effect on the seismic behavior increases with the building height, and is more evident in the SCCBFs than the BRBFs.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.737-742
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• 2011

Because of complex structure of inlet and outlet flows, the performance of centrifugal fans used in a household refrigerator is affected by many parameters of duct system surrounding the fans. In this paper, the performance of a centrifugal fan is numerically analysed according to shapes of inlet bell-mouth. To improve performance of the centrifugal fan, some design parameters are selected for comparison. On a basis of these comparison, optimum shape of inlet bell-mouth is proposed to maximise the flow rate of the fan.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.2
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• pp.163-169
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• 2013

In order to make the vertical-axis cross flow wind turbine commercially feasible, a guide vane is adopted and the effect of the guide vane shape is examined in order to improve the wind turbine performance. CFD analysis on the performance and internal flow of the turbine is carried out for the wind turbine model. The result shows that when the guide nozzle is installed, almost over two times of power coefficient are achieved in comparison with the case of no guide nozzle installation. The guide nozzle acts as a role of suppressing the flow resistance at the blade passage, which is found when the guide nozzle is installed. Moreover, in this study, two kinds of the guide vane with a straight type and a curved type are adopted and compared. The curved guide vane nozzle produces higher power coefficient in comparison with that of straight guide vane nozzle.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.215-219
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• 2007

For Web server implementations, there are 4 main schemes: process-per-request (PPR), thread-per-request (TPR), worker thread pool (WTP), and worker thread pool with buffers (WTPB). This paper compares performance of the schemes in response time point of view. WTPB shows the best performance. The appropriate number of worker threads for WTPB depends on the request service time. For short requests, the number can be very small. But for longer requests, it is about 1/6 of the number of simultaneous connections.

• Journal of Korean Academy of Nursing
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• v.27 no.4
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• pp.807-819
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• 1997

The purpose of the study was to identify the effects of a 12-week low-intensity exercise program on muscle strength, flexibility, balance, and cognitive characteristics related to the performance of activity of daily living(ADL). A total of 16 patients who were admitted to the medical unit of a general hospital in ChoongChung province were recruited, eight for the exercise group and eight for the comparison group. Four levels of low-intensity exercise from 'ROM on bed' to 'exercise while walking' were then applied to the exercise group according to their physical condition. During hospitalization, patients in the exercise group performed each level of the prescribed exercise with the researchers until they felt comfortable doing it independently. The researchers also visited the patients' homes after discharge to make sure they could perform the exercise with Theraband in their living environment. The exercise group was contacted by phone once a week to assess the frequency and intensity in which they performed the exercise as well as their physical condition. The subjects in the comparison group participated in measurements for the study without performing the exercise and were contacted by phone after discharge, in a matched time frame with the exercise group, to assess physical condition. Muscle strength, flexibility, balance, cognitive characteristics, and performance of ADL for the two groups were compared at the pretest and the posttest after the low-intensity exercise program by utilizing SPSSWIN and the results are as follows : 1) At the postest, measurements of muscle strengths showed that the strength of the dorsal flexor in the exercise group was significantly higher than in the comparison group. 2) Objective balance for the exercise group was significantly better than for the comparison group as measured by 'standing on one foot' and Tinetti gait and balance control. 3) The exercise group showed significantly higher task self-efficacy than the comparison group. 4) Perceived exertion for ADL for the exercise group was significantly lower than for the comparison group. 5) Improvement of performance of ADL without assistance was significantly higher for the exercise group than the comparison group. The findings suggest that a low-intensity exercise program would be useful for the elderly who show decline in their physical functioning due to hospitalization by partly improving physical strength, task self-efficacy, and performance of ADL. Directions for further research on issues of motivating people to exercise as well as of standardizing various types of exercise were discussed.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.39.2-39.2
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• 2005

• Journal of the Korean Solar Energy Society
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• v.34 no.4
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• pp.51-56
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• 2014

In this paper, OTEC(Ocean Thermal Energy Conversion) system with vapor-vapor ejector is newly proposed. And 6 wet refrigerants are applied into the proposed OTEC system for performance comparison. The results of comparison performance are as follows. In the view of system efficiency, R32/R744(90:10) has the highest efficiency among the 6 refrigerants. In case of evaporation capacity, pump work and mass flow rate of working fluid, R744, R717 and R717 is lowest value, respectively. As this results, the vapor-vapor ejector is able to increase the efficiency of system. And It is necessary to select the optimized working fluid considering environmental and economic factors.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.63-70
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• 2005

Various schemes for mobility are currently studied in ITU-T, 3GPP, IETF, and so on. Mobility support in NGN for seamless service is necessarily required. Currently proposed mechanisms are MIPv6, $IP^2$, and Q.MMF. However the performance comparison of all existing schemes is not examined as yet. That is, the existing methods need to be compared according to each performance parameter. So, in this paper, we investigate and compare the performances of MIPv6, $IP^2$, Q.MMF to location registration. In addition, this paper presents the performance comparison of handover latency times. For this, we use NS-2 simulator. As a result of analysis, $IP^2$ shown the best performance as it is measured the minimum time and cost. And it has low handover latency time in comparison with other mechanisms.