• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.73-78
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• 2020

In this study, a novel reactive power control scheme is proposed to supply stable reactive power to the distribution line by compensating a ripple voltage of DC link. In a single-phase system, a magnitude of second harmonic is inevitably generated in the DC link voltage, and this phenomenon is further increased when the capacity of DC link capacitor decreases. Reactive power control was performed by controlling the d-axis current in the virtual synchronous reference frame, and the voltage control for maintaining the DC link voltage was implemented through the q-axis current control. The proposed method for compensating the ripple voltage was classified into three parts, which consist of the extraction unit of DC link voltage, high pass filter (HPF), and time delay unit. HPF removes an offset component of DC link voltage extracted from integral, and a time delay unit compensates the phase leading effect due to the HPF. The compensated DC voltage is used as feedback component of voltage control loop to supply stable reactive power. The performance of the proposed algorithm was verified through simulation and experiments. At DC link capacitance of 375 uF, the magnitude of ripple voltage decreased to 8 Vpp from 74 Vpp in the voltage control loop, and the total harmonic distortion of the current was improved.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.33-42
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• 2016

Utilization of cultural contents is more and more increasing as it is believed to improve local problems and provide historical values. This kind of business is positive in terms of the fact that it attracts visitors into local areas and activate local commercial areas. Under this trend, the construction of specialized streets is required to be approached with first priority to solve problems of cities. So to speak, it's more important to solve intrinsic problems found in local communities and then approach cultural contents step-by-step rather than constructing new spaces with first priority. Moreover, cultural contents should accompany economic aspects which result in local community-friendly and sympathetically concentrated values. Under this sentiment, the efforts to suggest economic ripple effects for government local government's businesses using cultural contents are very important. This study analyzed how much economic ripple effects is yielded by reflecting cultural contents. As the result of analysis, specialized street with cultural contents applied are proved to be more concentrated on multiplier of expediting employment, income and tax and tourism industry than service industry. On the contrary to this, service industry showed more concentrated multiplier of expediting production, income, added values and chain reaction effect (coefficients for influence and sensitivity for front and rear side of tourism industry. Based on these results, construction of specialized streets with cultural contents applied is proved to help synergy effects for local economy.

• Journal of Information Management
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• v.42 no.3
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• pp.55-69
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• 2011

In the modern scientific R&D, the efficient acquisition, curation, analysis and visualization are core elements of the science development. The value of scientific data is very important in data intensive research. An output of scientific data is drastically increasing. However we have only each individual system of scientific data in now. Therefore We feel a lack of efficiency of scientific data. In this paper, We analyze an economic ripple effects in terms of production inducement effect, added value inducement effect, labor inducement effect and forward backward linkage effect of national scientific data center construction using an input-out analysis of the bank of Korea(2009). We also examine an economic propriety of national scientific data center construction.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.spc
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• pp.9-18
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• 2023

In the global manufacturing industry, digital transformation is emerging as an important issue for companies to improve productivity and strengthen industrial competitiveness. The government and shipbuilding companies drive research and development to attain advanced technologies through digital transformation for shipbuilding & offshore plants, one of Korea's representative manufacturing industries. Therefore, the digital transformation of the shipbuilding & offshore plant industry was defined using an input-output analysis model, and the economic interrelationships of industries linked to the digital transformation of the shipbuilding & offshore plant industry were analyzed. According to the analysis, the shipbuilding & offshore plant industry ranks second among all 34 industries regarding the forward linkage effect. The backward linkage effect was ranked 27th, making it a mid-demand industry with a robust forward linkage effect. In addition, the production-induced effect was 0.455, the value-added-induced effect was 0.174, and the employment-induced effect was 1.779 people per billion won. The contribution of this study is that it will provide the basis for establishing policies necessary to strengthen the competitiveness of the shipbuilding & offshore plant industry. Also, it will help analyze the economic effects of digital transformation in other manufacturing industries.

• Korean Journal of Construction Engineering and Management
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• v.20 no.2
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• pp.68-78
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• 2019

Recently, housing prices have surged, and the government has implemented various regulations, such as finance and taxes. Because of the policy, the nationwide housing price have stabilized, but polarization has occurred. Some argue that regulation can adversely affect the actual demand. Therefore, not only the correlation between market variables but also ripple effect of policy has to be analyzed in policy planning and analysis from a microscopic point of view. In this study, a simulation model was developed by integrating system dynamics for analyzing market structure and agent-based model for modeling decision process of market participants. This research applied the financial regulation and the tax regulation to the model and evaluated the policy effectiveness. This study reveals which feedback dominates according to the policies, which have same purpose. It is because market participants make different decision for each policy. Furthermore, there were other ripple effects not only in the policy target submarket but also in other submarket.

• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.78-84
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• 2019

The purpose of this study is to introduce the concept of the Smart Sewer System and to analyze the economic ripple effect when smart sewer is built all over Korea. The research method is the input-output model based on the assumption that the smart sewerage will be constructed throughout the Korea from 2021 to 2040. Estimation results show that the production-induced effect reaches 343.73 trillion Korean won, the added value-induced effect is 155.867 trillion Korean won, and the employment-induced effect is estimated by 25,118,470, indicating that the smart sewer project leads to being considerably large in the nation-wide economy. In addition, the increase of social welfare by smart sewer is expected to be realized through the improvement of both the environment improvement and the national health. Therefore, the smart sewer project should be implemented without delay by planning a concrete road map and putting it into effect with a budget.

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.7-14
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• 2016

The economic crisis in North Korea has reduced its capacity to invest in the energy industries. The country is going through a vicious cycle of decreased investment in the energy industries and reduced energy production. This suggests that the energy industries would come to the top priority of investment once the economy improves. This paper calculated the economic ripple effect of the investment on North and South Korean economies based on the assumption that 390 billion won was invested in the construction of a natural gas combined-cycle power plant in Gaesong Industrial Complex. In order to analyze the economic ripple effect of the investment on North Korean economy, we constructed the inter-industry relation table of North Korea for year 2014 and used the input-output model. The ripple effect of the investment in the natural gas industry turned out to be 1.012 billion dollars. In order to analyze the effect of the investment on South Korean economy, we constructed the inter-industry relation table of South Korea for year 2013 and used the demand-driven model for inter-industry analysis. As a result, production, added-value and employment inducement coefficients of the investment in the natural gas industry were calculated as 2.02073, 0.62697 and 8.99409 respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.2
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• pp.63-71
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• 1992

A solution method is developed for computing the bed shear stress driven by combined wave and current flow on a natural mobile coastal beach. An empirical equation is introduced to determine the shape of ripples formed on the natural sandy beach. The model being based on the Prandtl's mixing length theory, the effect of arbitrarily-angled interaction is included in the estimation of current velocity reduction and all numerical integrations are expressed by explicit approximate equations to improve the computation speed. In addition the computed sediment transport rates were compared with the measured values reported in literature. using the refined bottom friction model considering the ripple formation.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.38-40
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• 2008

This paper presents the torque ripple and vibration characteristic of interior type permanent magnet (IPM) motor according to rotor design. In the design methods, the optimal notchs are put on the rotor pole face, which have an effect on variation of permanent magnet (PM) shape or residual flux density of PM. Through the space harmonics field analysis, the positions of notch are found and the optimal shapes of notch are decided by using Finite Element Method (FEM). The validity of the proposed method is confirmed with experiments. Therefore, the vibration, starting current and efficiency of IPM is measured by experiment.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.605-607
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• 2004

A class D digital audio amplifier with small size, low cost, and high quality is positively necessary in the multimedia era made of home theater system and the digital audio broadcasting (DAB). It is impossible to analyze the stability of the digital audio amplifier, which is based on the PWM signal processing. To solve this problem, the digital audio amplifier is analyzed using variable structure control theory which is one of nonlinear system theories. Moreover, the magnitude and the frequency of ripple signal, which generated by hysteresis in the comparator, is obtained using describing function which is useful to represent the input-output relation of nonlinear system.