• New & Renewable Energy
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• v.18 no.2
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• pp.50-59
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• 2022

The Korean government announced the "1st Basic Plan for the Transition to Hydrogen Economy" in 2021 and declared the establishment of a hydrogen industry ecosystem by 2040. To build a low-carbon power system, resources that can efficiently accommodate renewable energy are required, and green hydrogen is considered a potential solution. This study analyzed the economic feasibility of green hydrogen-based sector coupling to reduce curtailment of renewable generation in the Jeju power system by 2025 under the scenario of with or without HVDC#3. The result showed that HVDC#3 significantly reduced the frequency of curtailment from 16.1% to 3.0%. In addition, green hydrogen-based sector coupling was an economically feasible option as result showed an IRR of 4.86% when HVDC#3 was connected and 11.45% when it was not under the condition of achieving 50% curtailment reduction. This study shows that the higher the level of renewable energy deployment, the more delayed the HVDC connection between Jeju and the main land, and the lower the SMP, the more economically feasible the green hydrogen-based sector coupling is. Furthermore, this study suggests that the policy goal of completely reducing curtailment is not economically efficient.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.5
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• pp.397-407
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• 2022

The informal economy is a large part of the urban economy. The informal economy accounts for about half of Pakistan's GDP. This research examined nine different areas of Rawalpindi's Central Business District's business sector (CBD). A survey of 404 respondents from 16 CBD marketplaces enables a comprehensive examination of who works in the informal and formal economic sectors, how much they earn, their goals, perception of their job, and their degree of similarity to the rest of the working population. Furthermore, the statistics illustrate the pro-cyclical connections between the informal economic sector and the formal economy. The Multinomial Logistic Regression (MLR) technique is used for the analysis. The MLR results indicated the informal economic sector holds positive relation with earning members in a family, business expertise, average business sale, and negative relation with education level, satisfaction with government tax policies, household expense, and average investment in the business. From a resilience standpoint, governance is considered an intentional collective action to preserve a stable system condition. Hence, the current study recommends tax reforms and government institution reorganization to mobilize the informal sector and make effective institutional governance.

• Journal of the Korean Society of Combustion
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• v.7 no.2
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• pp.7-14
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• 2002

The probability density functions (PDF) of temperature were measured by coherent anti-Stokes Raman Spectroscopy (CARS) in flames of gas turbine combustor sector rig of an aero-engine. The combustor was operated at simulated ground idle conditions with standard kerosene fuel. Temperature PDFs had been measured near fuel nozzle with change of rotation of a swirler and existence of a prefilmer. The characteristic features of temperature PDFs showed the variation of combustion configurations at four experimental conditions. Without a prefilmer, large recirculation of high temperature gas was expected in the co-flow condition and un vaporized fuel fragments were detected in the counter-flow condition. With a prefilmer, the enhanced mixing increased combustion intensity near fuel nozzle in the counter-flow condition and the flame was attached far from the fuel nozzle in the co-flow condition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.502-508
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• 2014

In this paper, a delay-dependent $H_{\infty}$ filtering problem is investigated for discrete-time delayed nonlinear systems which include a more general sector nonlinear function instead of employing the commonly used Lipschitz-type function. By using the Lyapunov-Krasovskii functional approach, a less conservative sufficient condition is established for the existence of the desired filter, and then, the corresponding solvability condition guarantee the stability of the filter with a prescribed $H_{\infty}$ performance level. Finally, two simulation examples are given to show the effectiveness of the proposed filtering scheme.

• Journal of the Korean Home Economics Association
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• v.41 no.2
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• pp.65-92
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• 2003

This study explored and described the life course of poor female household heads. The data was gathered by in-depth interviews with thirteen poor female heads of households. Most of poor female household heads grew up in poor families. nev could not be educated properly due to their families' poverty and boy preference, and they moved to urban areas to become informal sector laborers. After the marriages, their living conditions became worse, because many of them got married to so lazy men who had alcoholic problems that were not willing to provide their families. The poor female heads of households were under difficulties owing to low income and unstable labor Condition. The economic hardship disturbed the interaction with kins and friends. Although they got in touch with these people, they had uncomfortable feelings because they did not have enough resources which made these relationships reciprocal. Therefore, social welfare policy were essential to support the poor female heads of households.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.05a
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• pp.47-51
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• 2001

According as the controlled plants become more complex and large-scaled, the development of more intelligent control schemes is required in the control field. A fuzzy logic control (FLC) is one of proper schemes for this tendency. Recently, fuzzy control has been applied successfully to many industrial applications due to a number of advantages. But it still has some disadvantages. The conventional FLC has many tuning parameters: membership functions, scaling factors, and so forth. In order to improve this problem, a single-input fuzzy logic control (SFIC) which greatly simplifies the design process of the conventional FLC was proposed. Many research has also been proposed to develop the stability analysis of the FLC. In this paper we analyze the absolute stability of the SFLC. We first expand a nonlinear controlled plant into a Taylor series about a nominal operating point. And a fuzzy control system is transformed into a Lure system with nonlinearities. We also prove that the closed-loop system with the SFLC satisfies the sector condition globally.

• Structural Engineering and Mechanics
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• v.83 no.6
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• pp.825-834
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• 2022

The effectiveness and accuracy of the strain-based approach applied for analysis of two kinds of heterogeneous hollow cylinders subjected to thermal and mechanical loads are examined in this study. One is a multilayer cylinder in which the material in each layer is assumed to be linearly elastic, homogeneous and isotropic. Another is a hollow cylinder made of functionally graded materials with arbitrary gradient. The steady state condition without heat generation is considered. A sector in-plane finite element in the polar coordinate system based on strain approach is used. This element has only three degrees of freedom at each corner node. Analytical solutions available in the literature are presented to illustrate the accuracy of the sector element used. The obtained results for displacements and stresses are shown to be in good agreement with the analytical solutions.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.40.2-40.2
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• 2010

It has been reported that geosynchronous magnetopause crossings are more frequently observed in the prenoon sector than in the postnoon sector, indicating a dawn-dusk magnetopause asymmetry during extreme solar wind conditions. Motivated by these observations, we investigate geosynchronous magnetic field variations normalized to SYM-H when sudden commencements (SC) are observed on the ground. From a statistical analysis of the geosynchronous magnetic field responses to SC events from 1997 to 2006, we found that the normalized SC amplitude at geosynchronous orbit is larger in the morning sector than in the afternoon sector. In order to examine if this morning-afternoon asymmetry at geosynchronous orbit occurs only during disturbed geomagnetic conditions, we compared the geosynchronous magnetic field strength obtained in the morning and afternoon during undisturbed intervals (Kp < 3). We found that the asymmetry appears under undisturbed geomagnetic conditions and it is not due to solar wind aberration. This indicates that the morning-afternoon asymmetry was not strongly affected by changes in solar wind condition. Using solar wind data, we discuss what causes the morning-afternoon asymmetry at geosynchronous orbit.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.4
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• pp.304-312
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• 2008

In this study, the performance analysis was divided into the public sector and private business sector. The four perspectives of the BSC performance analysis for the private business sector can be applied to all of the enterprises as there are Logical Linkages between the four Perspectives. However, these can not be applied in the same way to the public sector. There is no Logical Linkage between public sector and private sectors. Therefore, since there is no Logical Linkage, the KIX project of the public sector has a constrained condition. With the internal and external perspective views, the BSC of the KIX identifies the quality(operation) factor, user(customer) satisfaction factor, and economic costs effects(finance) factor. Based on the linkage model in both the internal and external perspective views and the BSC performance analysis of these views, a performance analysis model was developed and then performance results were analyzed of the whole KIX project.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.1
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• pp.15-22
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• 2021

This study aims to obtain a stock investment strategy model based on the industrial sector in Indonesia Stock Exchange (IDX). This study uses IDX data for the period of January 1996 to December 2016. This study uses the Markov Regime Switching Model to identify trends in market conditions that occur in industrial sectors on IDX. Furthermore, by using the Logit Regression Model, we can see the influence of economic factors in determining trends in market conditions sectorally and the probability of trends in market conditions. This probability can be the basis for determining stock investment decisions in certain sectors. The results showed descriptively that the stocks of the consumer goods industry sector had the highest average return and the lowest standard deviation. The trend in sectoral stock market conditions that occur in IDX can be divided into two conditions, namely bullish condition (high returns and low volatility) and bearish condition (low returns and high volatility). Differences in the conditions are mainly due to differences in volatility. The use of a Logit Regression Model to produce probability of market conditions and to estimate the influence of economic factors in determining stock market conditions produces models that have varying predictive abilities.