• Solar Energy
• /
• v.19 no.4
• /
• pp.63-69
• /
• 1999

The conventional grid connected PV(Photovoltaic) system has a unstable output pattern due to its dependence on the weather condition, although solar-cell array averagely has a regular output characteristics to have a peak output nearly at noon. Therefore assuming the high density grid connection in the future, this unstable output pattern can be one of the main reasons to generate power disturbance such as voltage variation, frequency variation and harmonic voltage generation in low voltage distribution line. However general grid connected solar-cell system do not have functions to cope with these disturbances. Therefore this study proposed a advanced type grid connected PV system with functions to suppress output power fluctuation due to solar-cell array output variation and showed the levelling effect of fluctuation due to instantaneous array output variation.

• The Journal of Advanced Prosthodontics
• /
• v.13 no.3
• /
• pp.136-143
• /
• 2021

Purpose. This study aimed to evaluate the effect of repeated use of an implant handpiece under an implant placement torque (35 Ncm) and overloading torque condition (50 Ncm) on an output torque. Materials and Methods. Two types of implant handpiece systems (Surgicpro/X-DSG20L [NSK, Kanuma, Japan] and SIP20/CRB46LN [SAESHIN, Daegu, South Korea]) were used. The output torque was measured using a digital torque gauge. The height and angle (x, y, and z axes) of the digital torque gauge and implant handpiece were adjusted through a jig for passive connection. The experiment was conducted under the setting torque value of 35 Ncm (implant placement torque) and 50 Ncm (overloading torque condition) and 30 times per set; a total of 5 sets were performed (N = 150). For statistical analysis, the difference between the groups was analyzed using the Mann-Whitney U test and the Friedman test was used to confirm the change in output torque (α=.05). Results. NSK and SAESHIN implant handpieces showed significant differences in output torque results at the setting torques of 35 Ncm and 50 Ncm (P<.001). The type of implant handpiece and repeated use influenced the output torque (P<.001). Conclusion. There may be a difference between the setting torque and actual output torque due to repeated use, and the implant handpiece should be managed and repaired during long-term use. In addition, for successful implant results in dental clinics, the output torque of the implant handpiece system should be checked before implant placement.

• Laser Solutions
• /
• v.2 no.2
• /
• pp.42-51
• /
• 1999

This study has been performed to investigate into some effects of the output power and traverse speed of laser beam on the microstructures, hardness and fatigue resistance of the ductile iron surface-hardened by $CO_2$ laser defocussed beam. Optical micrographs have shown that with increasing the output power and decreasing the traverse speed, the martensite was coarsened and some retained austenite were appeared in ductile iron. The microstructures of hardening zone were composed of bull's eye and some nodular graphite dissolved structures by the effect of self quenching. Fatigue fracture characteristics of ductile iron have appeared in the high stress and low stress ranges. The fracture initiated at nodular graphites in the surface hardened layer due to the stress concentration caused by a notch effect. The interior graphite nodules were broken away or popped out during crack propagation. Fatigue test has shown that values of fatigue strength considerably increased with increasing output power at a given traverse speed.

• Smart Structures and Systems
• /
• v.7 no.1
• /
• pp.59-82
• /
• 2011

In this study, an output-only modal identification approach is proposed for decentralized wireless sensor nodes used for linear structural systems. The following approaches are implemented to achieve the objective. Firstly, an output-only modal identification method is selected for decentralized wireless sensor networks. Secondly, the effect of time-unsynchronization is assessed with respect to the accuracy of modal identification analysis. Time-unsynchronized signals are analytically examined to quantify uncertainties and their corresponding errors in modal identification results. Thirdly, a modified approach using complex mode shapes is proposed to reduce the unsynchronization-induced errors in modal identification. In the new way, complex mode shapes are extracted from unsynchronized signals to deal both with modal amplitudes and with phase angles. Finally, the feasibility of the proposed approach is evaluated from numerical and experimental tests by comparing with the performance of existing approach using real mode shapes.

• Journal of Power Electronics
• /
• v.19 no.5
• /
• pp.1122-1132
• /
• 2019

In this paper, aiming at high-voltage applications, transformer windings schemes of multiple-output two-transistor flyback converters are investigated, which are mainly based on the stray capacitances effect. First, based on a transformer model including equivalent stray capacitors, the operational principle of the converter is presented, and the main influence of its stay capacitors is determined. Second, the windings structures of the transformer are analyzed and designed based on the stray capacitances effect. Third, the windings arrangements of the transformer are analyzed and designed through a coupling analysis of the secondary windings and a stray capacitance analysis between the primary and secondary windings. Finally, the analysis and design conclusions are verified by experimental results obtained from a 60W laboratory prototype of a multiple-output two-transistor flyback converter.

• Proceedings of the KIEE Conference
• /
• 1997.07e
• /
• pp.1874-1876
• /
• 1997

A fiber optic voltage sensor using photoelastic effect of a single-mode optical fiber, excited with a 632.8 nm He-Ne laser, is developed. The photoelastic effect is produced by piezoelectric effect for the voltage measurement. It is found that the detector output voltage is proportional to the applied voltage. Also, the frequency of the output voltage is equal to that of the applied voltage. Experimental results from a laboratory model demonstrate the feasibility of the sensor for field application in high-voltage systems.

• Journal of Information Technology Applications and Management
• /
• v.13 no.1
• /
• pp.67-75
• /
• 2006

In this paper, we investigate the economic repercussion effects of the domestic satellite industry. The market size of the satellite industry between 2005 and 2009 is forecasted based on the world market forecast. By using the Input-Output analysis technique, three kinds of repercussion effects (domestic production, value added, workers induced by the satellite industry) between 2005 and 2009 are calculated.

• Journal of Korean Society of Rural Planning
• /
• v.15 no.2
• /
• pp.69-80
• /
• 2009

The purpose of this paper is to estimate the regional economic impact of reverse mortgage system based on farmer's net asset of house and farmland together. The regional economic impact was estimated by using inter-regional input-output model. Major findings are as follows: 1) The result of input-output analysis shows that 49,130 million won of production effect, 20,040 million won of value added effect, and 24,759 number of employment effect, 2) Since the result shows that the elderly spend most of the reverse mortgage money for their living expenses, it seems necessary to adopt net asset based reverse mortgage system to improve and stabilize farmers' living conditions and regional economy.

• Proceedings of the Technology Innovation Conference
• /
• 2006.02a
• /
• pp.44-77
• /
• 2006

The technological innovation has been recognized critical factors of productivity of firms and key contribution of improvement of firm performance for a long time. Many researchers have investigated the relationship between R&D investment or patents as a proxy of innovation and productivity. But there were some problem such as lacking of data and ambiguity of innovation definition. So, previous literatures have some difficulty in reliability of analysis for using only survey data. And investigating the relationship R&D and other factors is very difficult. Therefore, this paper tries to investigate and analysis the relationship between innovation and performance of Korean manufacturing firms. Using KIS2002(Korean Innovation survey 2002) which was based on Oslo manual in 2002 and financial data of firms (KISINFO), I will intend to establish the reliability of multiple analysis. In detail, I will investigate whether the innovation input have effect on the innovation output, whether the innovation output have effect on productivity for heterogeneity and what factor of innovation environment have effect on the innovation itself.

• The KSFM Journal of Fluid Machinery
• /
• v.11 no.4
• /
• pp.45-51
• /
• 2008

The purpose of this study is to examine the effect of nozzle shape on the performance and internal flow of a cross-flow hydro turbine. CFD analysis for three kinds of nozzle shape is conducted to simulate the effect of nozzle shape. The results reveal that relatively narrow nozzle width is effective to increase the turbine efficiency and output power. Almost output power is achieved at Stage 1. Therefore, optimum design of the nozzle shape is necessary to improve the turbine performance. Recirculation flow in the runner passage decreases the turbine efficiency and output power because the flow make hydraulic loss and collision loss in the region. Air should be put into the runner passage and the recirculating flow should be suppressed by the air layer in the runner.