• Journal of the Korean Society of Combustion
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• v.19 no.4
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• pp.8-13
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• 2014

Flow distribution of fuel nozzles for a combustor in a micro gas turbine is numerically investigated. The fuel supply system for the present study has 12 single nozzles with a diameter of several hundred micrometers. A uniform temperature distribution of a combustor outlet should be achieved for maximizing the lives of the turbine blades and nozzle guide vanes. For this, it is very important to uniformly supply fuel to a combustor. In order to investigate flow distributions of fuel nozzles, numerical models for fuel nozzles are made and solved by a commercial code, ANSYS FLUENT. An effect of a fuel nozzle diameter and fuel flow rates on flow distribution of fuel nozzles is numerically investigated. As a result, non-uniformity is increasing as a diameter of a single fuel nozzle increases. Finally, an appropriate diameter of a single fuel nozzle is suggested.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.461-470
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• 2014

This paper presents a probabilistic power flow (PPF) analysis method for distribution network incorporating the randomness and correlation of photovoltaic (PV) generation. Based on the multivariate kernel density estimation theory, the probabilistic model of PV generation is proposed without any assumption of theoretical parametric distribution, which can accurately capture not only the randomness but also the correlation of PV resources at adjacent locations. The PPF method is developed by combining the proposed PV model and Monte Carlo technique to evaluate the influence of the randomness and correlation of PV generation on the performance of distribution networks. The historical power output data of three neighboring PV generators in Oregon, USA, and 34-bus/69-bus radial distribution networks are used to demonstrate the correctness, effectiveness, and application of the proposed PV model and PPF method.

• Journal of Distribution Science
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• v.20 no.8
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• pp.115-121
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• 2022

Purpose: This article aims to explore the distribution of technological innovation and environmental policy challenges to respond to COVID-19. The study also attempts to tackle a paradigm shift in science and technology policies against the pandemic and a desirable direction for environmental policies. The COVID-19 pandemic has been the one that rapidly changed global people's lifestyle. For the spread of a terrible infectious disease could not be avoided, regardless of a highly industrialized society. Research design, data and methodology: This study basically employs a qualitative approach as a methodology. This study is based on the fact that environmental pollution, various natural disasters continuously occur, and there are many unforeseeable parts, despite remarkable development of scientific technology, and that the circumstances are becoming more complex. Results: This study noted that scientific technology civilization formed due to industrial revolutions can deteriorate environment and increase environmental threat factors. As an alternative to this, this study investigates alternative discussions on how the 4th Industrial Revolution can help scientific technology and human environment to harmoniously coexist and develop. Conclusions: It implies that this study focuses on the possibility of overcoming this crisis through science and technology innovation, although mankind is in crisis of COVID-19 due to excessive human development.

• Journal of Multimedia Information System
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• v.1 no.2
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• pp.127-132
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• 2014

The transverse electromagnetic (TEM) cells are widely used for electromagnetic compatibility (EMC) testing and field probe calibrations. We propose the verification of TEM mode with statistical method using a four-port TEM cell. The verification results are compared with Normal, Rayleigh, and Gamma distribution. As a result, the 75 % quantile of the Rayleigh distribution is excellent agreement with the true quantiles for a number of calibration points.

• Journal of Industrial Technology
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• v.15
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• pp.33-40
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• 1995

This paper presents a new method for load distribution in a single-level tree network equipped with front-end processors. This method focuses on effective data distribution over a number of processors minimize job processing time. Optimal multiple installment load distribution algorithm is presented. Minimum number of processors that maximizes efficiency is decided theoretically.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.04a
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• pp.6-10
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• 1999

We present a simulation result to the analysis of the effects of cell residence time distributions upon the expected channel occupancy time based on an analytic mobility model. Numerical examples show that exponential distribution provides upper and lower bound to the expected channel occupancy times of new calls and handoff calls. This fact reveals that the assumption of exponential distribution as the cell residence time distribution as the cell residence time distribution may over- or under-estimate cellular mobile systems.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.644-647
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• 1996

The distribution of coercivity in the thickness direction were investigated by using Kerr hysteresis loop tracer for the Co-Cr films deposited by Facing Targets Sputtering apparatus. It was found that the difference between the coercivities of surface layer and initial growth layer H$_c$$\bot$(S)-H$_c$$\bot$(I) correlated strongly with $\Delta$H$_o$, shich represents the degree of distribution of coercivity. Furthermore, the Cr content was varied in order to improve the coercivity of imitial growth layer H$_c$$\bot$(I) and distribution of coercivity. H$_c$$\bot$(I) took a maximum value of 750 Oe and the distribution of coercivity became sharper at the Cr content of 25at. %.

• Journal of Mechanical Science and Technology
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• v.19 no.5
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• pp.1065-1071
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• 2005

In this study, residual stress distribution in multi-stacked film by MEMS (Micro-Electro Mechanical System) process is predicted using Finite Element method (FEM). We evelop a finite element program for residual stress analysis (RESA) in multi-stacked film. The RESA predicts the distribution of residual stress field in multi-stacked film. Curvatures of multi­stacked film and single layers which consist of the multi-stacked film are used as the input to the RESA. To measure those curvatures is easier than to measure a distribution of residual stress. To verify the RESA, mean stresses and stress gradients of single and multi layers are measured. The mean stresses are calculated from curvatures of deposited wafer by using Stoney's equation. The stress gradients are calculated from the vertical deflection at the end of cantilever beam. To measure the mean stress of each layer in multi-stacked film, we measure the curvature of wafer with the left film after etching layer by layer in multi-stacked film.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.239-244
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• 2012

In this paper, we first introduce our own binary CDMA technology. Then we propose a wireless distribution automation system using the binary CDMA technology. The major research items are the binary CDMA distribution automation system, piconet configuration for remote control and monitoring, scheduling for the transmission and reception of data, and ways of applying encryption to protect wireless packet. To verify the possibility of applying wireless transmission to the distribution automation system, we experiment the implemented system in terms of the transmission rate by applying it to a real-world environment.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.3
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• pp.86-90
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• 2003

This paper describes the electrical characteristics of Nomex paper employed as an insulating material for distribution transformers. The relative permittivities (dielectric constants) and tan$\delta$ (dielectric dissipation factors) were measured as dielectric characteristics and the partial discharge inception voltages (PDIVs) and breakdown voltages were also measured as electrical strength characteristics of Nomex paper. As a result, the permittivity and tan $\delta$ of Nomex paper demonstrated both temperature and frequency dependency. Of particular note, the permittivity of 0.18 mm Nomex paper was 2.4 according to the ASTM condition, The PDIVs and breakdown voltages were almost linearly increased with the thickness of Nomex paper. Furthermore, its electrical strength was superior to conventional Kraft paper.