• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.128-133
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• 2008

This paper describes underwater discharge phenomena and breakdown characteristics in case that the standard lightning impulse voltage is injected to the needle and spherical electrodes installed in the hemisphere water tank. The objective of this work is to understand the basic features related to transient ground impedance against lightning surges. The discharge luminous images were observed and the dependence of breakdown voltage on the polarity of applied voltage and water resistivity were investigated. As a consequence, streamer corona is initiated at the tip of needle and spherical electrodes and is propagated toward grounded tank with stepwise extension. The breakdown voltage characteristics measured as a function of water resistivity showed V-shaped curves. Breakdown voltage and time curve of needle electrode is higher than that of spherical electrode.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1313-1314
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• 2008

현재 AC-PDP의 문제점 중 하나인 오방전 개선을 위한 연구가 진행되고 있다. 본 연구에서는 AC-PDP의 오방전 분석을 위해서 오방전 발생 메커니즘을 분석하고, 패널의 시간 변화에 대한 특성과 고온, 저온에서의 패널 특성을 파악하기 위해 휘도, 방전개시전압, discharge time lag 등을 측정하였다. 그리고 sustain pulse의 수를 조절함으로써 패널내의 priming 조건을 제어하면서 오방전 발생 확률을 수치적으로 측정하였다. 패널의 aging시간에 따라 MgO sputtering 등으로 인한 방전 공간의 변화로 방전개시전압의 변화를 관찰하였으며 그로 인한 오방전 발생이 증가함을 알 수 있었다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.1
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• pp.87-99
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• 1992

A mathematical model, UNSATR which predicts the seepage flow through the body of dike especially under the tidal fluctuation has been developed. This model has been revised from UNSAT2 model which was developed on the basis of the saturated-unsaturated theory by Neuman. UNSATR has been verified and applied to the hydraulic model in order to estimated the seepage quantity, the formation of free water surface etc. The results lead to the following conclusions : 1. Seepage rates between the mathematical model and hydraulic model experiment are very similar to each other both in constant and transient water level conditions. 2. The lapsed time to be steady state of the free water surface becomes late as the tidal levels are relatively low mainly due to the seepage flow from the unsaturated zone of the body of dike. 3. Under the transient state of water levels, owing to the flow from the unsaturated domain, streamlines crossing to the free water surface are found and time lag during a falling tide may allow the free water surface inside the body of dike to stand at a high level than the outside water level. 4. The utility and validity of UNSATR model are convinced when the analyses on seepage problems through the porous embankment of the soil structures on the conditions of the steady and unsteady states are carried out.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.8
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• pp.114-121
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• 2011

This paper, as the second part of the paper, dealt with the field test and test results to validate PSS(Power System Stabilizer) parameters which are previously tuned in Part 1 paper. In Part 1 of the paper, the selection of parameters such as lead-lag time constants for phase compensation and system gain was optimized by using linear & eigenvalue analyses and they were verified through the time-domain transient stability analysis. In part 2, the performance of PSS was finally verified by the generator's on-line field test. Through the comparisons of simulation results and measured data before and after tuning of the PSS, the models of generator and its controllers including AVR, Governor and PSS used in the simulation are verified and confirmed.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.5
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• pp.325-334
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• 2021

This study aims to investigate whether economic growth is elevated by banking industry development in Jordan. The study adopts time-series econometric methodologies, which comprise the bounds testing approach within the autoregressive distributed lag (ARDL) and the conditional causality analysis. Consistent with the assumptions of the adopted methodology, the study utilized annual time-series data for a relatively long period of thirty-nine years, between 1980 and 2018. The empirical results show that Jordan's economic growth is strongly responsive in respect to any changes in banking industry development. Also, the results reveal the harmful impact of rising lending interest rate; as this rate increases, economic growth will decrease. The findings are in line with the conceptual arguments of the supply-leading hypothesis, which confirmed that banking development is considered as one of the main pillars that have stimulating effects on economic growth. The evidence of the current study may provide important implications for policymakers and bankers. Those professionals should work to maintain a stable regulatory system that enhances the banking system function in activating economic growth. Also, a considerable focus should be placed on designing a steady interest rate policy to avoid the inherently undesirable impacts of high-interest rates on the Jordanian economy.

• Structural Engineering and Mechanics
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• v.85 no.3
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• pp.305-314
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• 2023

The article is about the theoretical analysis of the transmission and reflection of elastic waves through the interface of perfectly connected materials. The solid continuum mediums considered are piezoelectric semiconductors and transversely isotropic in nature. The connection among the mediums is considered in such a way that it holds the continuity property of field variables at the interface. The concept of strain and stress introduced by non-local theory is also being involved to make the study more applicable It is found that, the incident wave results in the generation of four reflected and three transmitted waves including the thermal and elastic waves. The thermal waves generated in the medium are encountered by using the concept of three phase lag heat model along with fractional ordered time thermoelasticity. The results obtained are calculated graphically for a ZnO material with piezoelectric semiconductor properties for medium M₁ and CdSc material with transversely isotropic elastic properties for medium M₂. The influence of fractional order parameter, non-local parameter, and steady carrier density parameter on the amplitude ratios of reflected and refraction waves are studied graphically by MATLAB.

• Journal of the Economic Geographical Society of Korea
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• v.25 no.4
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• pp.600-616
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• 2022

This study contemplates spatial context of startup in manufacturing, mainly analyzing job creation effects of time lag of startups in manufacturing at different technology levels. Using DID model, we found that each region including capital, non-capital and metropolitan area shows different job creation effects of time lag. In capial region, startup cohort in high R&D intensity manufacturing was found to show short-term job creation effects, but in non-capital region, long-term job creation effects was found with the one in medium-high R&D intensity manufacturing. In case of metropolitan area, we couldn't find much evidence of job creation effects that was statistically significant. The result of analysis implied that, in capital region, startup support policies, targeting at high R&D intensity manufacturing, ought to be focused on scale-up of startups that survived for a certain period. And non-capital area and some of metropolitan areas in non-capital region that have comparatively inferior infrastructure and brain-drain problems as well should focus on fostering startups in medium-high R&D intensity manufacturing in a long-term perspective and utilize their traditional manufacturing base.

• Journal of Sensor Science and Technology
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• v.29 no.4
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• pp.249-254
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• 2020

It is difficult to control children who exhibit negative behavior in dental clinics. Various methods are used for preventing pediatric dental patients from being afraid and for eliminating the factors that cause psychological anxiety. However, when it is difficult to apply this routine behavioral control technique, sedation therapy is used to provide quality treatment. When the sleep anesthesia treatment is performed at the dentist's clinic, it is challenging to identify emergencies using the current breath detection method. When a dentist treats a patient that is under the influence of an anesthetic, the patient is unconscious and cannot immediately respond, even if the airway is blocked, which can cause unstable breathing or even death in severe cases. During emergencies, respiratory instability is not easily detected with first aid using conventional methods owing to time lag or noise from medical devices. Therefore, abnormal breathing needs to be evaluated in real-time using an intuitive method. In this paper, we propose a method for identifying abnormal breathing in real-time using an intuitive method. Respiration signals were measured using a 3M Littman electronic stethoscope when the patient's posture was supine. The characteristics of the signals were analyzed by applying the signal processing theory to distinguish abnormal breathing from normal breathing. By applying a short-time Fourier transform to the respiratory signals, the frequency range for each patient was found to be different, and the frequency of abnormal breathing was distributed across a broader range than that of normal breathing. From the wavelet transform, time-frequency information could be identified simultaneously, and the change in the amplitude with the time could also be determined. When the difference between the amplitude of normal breathing and abnormal breathing in the time domain was very large, abnormal breathing could be identified.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.356-365
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• 2017

Most studies of the effects of corporate patents on managerial performance conducted to date have been based on internally-generated patents. However, global pharmaceutical and biotechnology companies acquire patents not only from internal research and development (R&D), but also through university-industry collaboration and purchase. Focusing on this issue, our study collected patents from various sources, including internal R&D, purchased patents, and university-industry collaboration, to examine the real effects more accurately. Additionally, our study used a finite time lag model to consider the time lag between patent and corporate performance. The results of the quantitative analysis of the relationship between patents and corporate financial performance revealed that patent quantitative levels had less impact on sales than other types. However, quantitative patents levels appeared to have a significant impact on market value. Moreover, quantitative patent levels appeared to moderate impact on corporate profit. Patents acquired by internal R&D had the greatest impact on market value, while purchased patents had the greatest impact on corporate profit and sales. The purchased patents had a significant effect on financial performance in the pharmaceutical and biotechnology companies because of the long time required and expense associated with R&D. Overall, the results of this study provide the basis for global pharmaceutical and biotechnology companies to configure an optimal patent portfolio.

• Environmental Engineering Research
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• v.22 no.3
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• pp.302-311
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• 2017

Nowadays, with the burgeoning development of economy, $CO_2$ emissions increase rapidly in China. It has become a common concern to seek effective methods to forecast $CO_2$ emissions and put forward the targeted reduction measures. This paper proposes a novel hybrid model combined principal component analysis (PCA) with regularized extreme learning machine (RELM) to make $CO_2$ emissions prediction based on the data from 1978 to 2014 in China. First eleven variables are selected on the basis of Pearson coefficient test. Partial autocorrelation function (PACF) is utilized to determine the lag phases of historical $CO_2$ emissions so as to improve the rationality of input selection. Then PCA is employed to reduce the dimensionality of the influential factors. Finally RELM is applied to forecast $CO_2$ emissions. According to the modeling results, the proposed model outperforms a single RELM model, extreme learning machine (ELM), back propagation neural network (BPNN), GM(1,1) and Logistic model in terms of errors. Moreover, it can be clearly seen that ELM-based approaches save more computing time than BPNN. Therefore the developed model is a promising technique in terms of forecasting accuracy and computing efficiency for $CO_2$ emission prediction.