• Journal of IKEEE
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• v.22 no.4
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• pp.1006-1011
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• 2018

This paper proposes a three level buck converter utilizing multi-bit flying capacitor voltage control. The conventional three-level buck converter can not control the flying capacitor voltage, so that the operation is unstable or the circuit for controlling the flying capacitor voltage can not be applied to the PWM mode. Also when the load current is increased, an error occurs in the inductor voltage. The proposed structure can control the flying capacitor voltage in PWM mode by using differential difference amplifier and common mode feedback circuit. In addition, this paper proposes a 3bit flying capacitor voltage control circuit to optimize the operation of the three level buck converter depending on the load current, and a triangular wave generation circuit using the schmitt trigger circuit. The proposed 3-level buck converter is designed in $0.18{\mu}m$ CMOS process and has an input voltage range of 2.7V~3.6V and an output voltage range of 0.7V~2.4V. The operating frequency is 2MHz, the load current range is 30mA to 500mA, and the output voltage ripple is measured up to 32.5mV. The measurement results show a maximum power conversion efficiency of 85% at a load current of 130 mA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.375-383
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• 2018

This study was carried out to grasp the economic effects of the social welfare foundation by establishing and operating it. For this purpose, the effects of the social welfare law of Daegu Metropolitan City on the regional economy were analyzed using the input-output analysis model. As a result, the effects of GDP was 43,445 billion won, the total value-added effect was 1,940 billion won, and the total employment inducement effect was 37,411. Based on these results, the future direction of the social welfare corporation is suggested as follows. First, it is necessary to shift the perception of consumer-oriented welfare toward welfare that contributes to the activation of the local economy. Second, efforts should be made to continuously expand employment linked to social welfare services, to create an environment where jobs can be created from a long-term perspective, and to establish a separate support system. Third, the value-added created by the social welfare foundation should be newly recognized and sought to be expanded in various fields. Fourth, efforts should be made to secure the legitimacy of social service provision and ensure accountability by appropriately promoting the economic ripple effects of social welfare foundation to the local community.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.755-760
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• 2016

The demand for independent generators using renewable energy has been increasing. Among those independent generators, small wind turbine generators have been actively developed. Permanent magnets are generally used for small wind turbine generators to realize a simple structure and small volume. On the other hand, cogging torque is included due to the structure of the permanent magnet synchronous machine, which can be the source of noise and vibration. The cogging torque can be varied by the shape of the permanent magnet and core, and it can be reduced using the appropriate design techniques. This paper proposes a design technique that can reduce the cogging torque by changing the shape of the permanent magnets for SPMSM (Surface Permanent Magnet Synchronous Motor), which is used widely for small wind turbine generators. Evolution Strategy, which is one of non-deterministic optimization techniques, was adopted to find the optimal shape of the permanent magnets that can reduce the cogging torque. The angle and outer diameter of permanent magnet were set as the design variable. A 300W class wind turbine generator, whose pole/slot combination was 8 poles/18 slots, was designed with the proposed design technique. The properties of the generator, including the cogging torque and output voltage, were calculated. The calculation results showed that the cogging torque of the optimized model was reduced compared to that of the initial model. The design technique proposed by this paper can be an effective measure to reduce the cogging torque.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.70-77
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• 2013

We suggest a low area and high efficiency switched-mode power supply (SMPS) with a pulse width modulation (PWM) generator based on a pseudo relaxation-oscillating technique. In the proposed circuit, the PWM duty ratio is determined by the voltage slope control of an internal capacitor according to amount of charging current in a PWM generator. Compared to conventional SMPSs, the proposed control method consists of a simple structure without the filter circuits needed for an analog-controlled SMPS or the digital compensator used by a digitally-controlled SMPS. The proposed circuit is able to operate at switching frequency of 1MHz~10MHz, as this frequency can be controlled from the selection of one of the internal capacitors in a PWM generator. The maximum current of the core circuit is 2.7 mA, and the total current of the entire circuit including output buffer driver is 15 mA at 10 MHz switching frequency. The proposed SMPS has a simulated maximum ripple voltage of 7mV. In this paper, to verify the operation of the proposed circuit, we performed simulation using Dongbu Hitek BCD $0.35{\mu}m$ technology and measured the proposed circuit.

• Journal of Korea Port Economic Association
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• v.34 no.2
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• pp.17-30
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• 2018

The regional industry promotion system, which seeks to link the characteristics and resources of the region to its core strategic industry, is spreading the industrial resources in the form of an organic network. The Seosan-Daesan Port is the only port in the Chungcheong provinces that is equipped with international passenger dock and terminal, and it will soon have a ferry service operating to the Longyan port in Rongcheng, China in 2018. The study focuses on effects of the first international ferry operation in the provinces that are being realized with the aim of developing the regional industry. The study also analyzes the ripple effects on the tourism and port industries in the provinces by tapping into the 2013 regional inter-industry table. The analysis shows that the scheduled ferry operation will generate 47,815 million won in production and 23,423 million won in added value for the region's tourism industry. It will also generate total revenue of 12,567 million won for the port industry driven by the locally handled freight containers and the added value. Currently, the Korea-China ferry operation in other regions exhibits greater dependence on the cargo than the passengers. Thus, for the international ferry operation to and from Seosan, generating maximum employment in tourism from the passengers of the international ferry operation will require strategic marketing to attract tourists. At the same time, a steady supply of cargo needs to be sustained by maintaining a balance between import and export cargoes. Furthermore, greater efforts should be made to create more sea routes than other regions or to increase voyages for the purpose of generating more added value.

• Journal of Convergence for Information Technology
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• v.10 no.3
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• pp.48-57
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• 2020

This study focuses on the development of simple qualitative indicators for evaluating and selecting innovation leading companies that challenge National Award. Another purpose of this study is to complement the aspect in which the innovative or value of the companies' products, technologies, and services is only quantitatively evaluated. Existing evaluation indicators of national award have too many evaluation items and were not suitable for innovation-based company evaluation. The research approach is to select category for developing qualitative indicators based on previous studies and TF discussion. From the input-process-output-outcome point of view, we have set up an indicator system as a series of flows. Finally, five categories such as creativity, system excellence, customer value, performance, and ripple effects are selected as qualitative indicator. For these selected indicators, conceptual definitions and the main points of evaluation are described. And the system level evaluation and the ADLI approach are presented for reference. The appendix also includes examples of qualitative and quantitative evaluation of real companies using these indicators. However, this study implies the possibility that the evaluation results may vary depending on the level and perspective of the evaluator. We hoped that detailed research on candidate indicators that can be used as qualitative indicators and research on the development of mixed indicators(qualitative and quantitative) will continue in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.35-42
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• 2019

Nut fasteners that require ultra-precise control are required in the overall manufacturing industry including electronic products that are currently developing with the automobile industry. Important performance factors when tightening nuts include loosening due to insufficient fastening force, breakage due to excessive fastening, Tightening torque and angle are required to maintain and improve the assembling quality and ensure the life of the product. Nut fasteners, which are now marketed under the name Nut Runner, require high torque and precision torque control, precision angle control, and high speed operation for increased production, and are required for sophisticated torque control dedicated to high output BLDC motors and nut fasteners. It is demanded to develop a high-precision torque control driver and a high-speed, low-speed, high-response precision speed control system, but it does not satisfy the high precision, high torque and high speed operation characteristics required by customers. Therefore, in this paper, we propose a control technique of BLDC motor variable speed control and nut runner based on vector control and torque control based on coordinate transformation of d axis and q axis that can realize low vibration and low noise even at accurate tightening torque and high speed rotation. The performance results were analyzed to confirm that the proposed control satisfies the nut runner performance. In addition, it is confirmed that the pattern is programmed by One-Stage operation clamping method and it is tightened to the target torque exactly after 10,000 [rpm] high speed operation. The problem of tightening torque detection by torque ripple is also solved by using disturbance observer Respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.323-332
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• 2019

The purpose of this study is to measure the effects on the regional economy from the Jeju International Wind Ensemble Festival. In order to examine the economic ripple effects of the festival, we examine its impact on the local economy using two regional (Jeju-National) industry-related models based on the 2013 Jeju Region Input and Output Table. We also compare how the Jeju International Wind Ensemble Festival is growing and affecting the regional economy through a comparison between 2017 and 2018. Comparing the results of a production-inducing and value added-effect analysis of the induced industries from investment expenditures for the Jeju International Wind Ensemble Festival, the production-inducing effects increased by 2.1 times-from 9.05 billion won in 2017 to 18.7 billion won in 2018. The value-added effect increased by 2.2 times, from nearly 4.3 billion won in 2017 to nearly 9.2 billion won in 2018. The analysis shows that the Jeju International Wind Ensemble Festival contributes greatly to an income increase for local residents. In order to enhance the effects of the Jeju International Wind Ensemble Festival, it is necessary to use policies that link culture and tourism in Jeju.

• Korea Trade Review
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• v.43 no.5
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• pp.25-45
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• 2018

This paper estimates the export losses of the Korean domestic automobile industry due to US trade pressure and its economic ripple effects. Using the HS 6 digit tariff and export data from 2010 to 2017, this paper estimates the tariff elasticity of Korea's US automobile exports against a US tariff increase by applying the Poisson Pseudo maximum likelihood estimation method. After estimating Korea's export losses to the US in three trade pressure scenarios, we estimate its impact on Korean domestic production, value-added and job creation by applying the tariff impact accumulation model based on the industry input-output analysis. Empirical results show that the impact of 25% global tariff by the US on the Korean domestic economy is estimated to result in $30.8 billion in export losses for the five years from 2019 to 2023, about 300 thousand job losses, 88.0 trillion in production inducement losses, and 24.0 trillion in value-added inducement losses. The impacts of withdrawal of the automobile tariff concession are estimated at $4.27 billion export losses and 41.7 thousand job losses. A 15% tariff rate on automobile parts for 3 years is estimated to result in $1.93 billion export losses and 18.7 thousand job losses.

• 한국체육학회지인문사회과학편
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• v.57 no.6
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• pp.123-134
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• 2018

The purpose of this study is to analyze the economic efficiency of the policy implemented by Ministry of Culture, Sports and Tourism on leading company in sport industry. The leading companies in sport industry are those who have a certain amount of sales in sport industry and the ones with potential to become global companies. Supporting areas include business advancement, overseas market development, and overseas PR marketing integration support. The research is performed by developing the equilibrium model composed of supply as well as demand and applying input-output analysis. The economic efficiency is estimated to in the form of changes in the sales of corporations and the ripple effect of the national economy. The results of the study are as follows. First, it is estimated that the sales growth rate of the company due to the implementation of the policy is from 3.74% to 5.19%. Second, the increase in sales reaches to a maximum of KRW 4,081 billion with a minimum of KRW 1,573 million, depending on the size of the company. Third, it is estimated that the production inducement effect for the national economy is from KRW 36 billion to KRW 93.4 billion. Fourth, the induced value added for the national economy is estimated to be at least KRW 11.3 billion, up to KRW 29.2 billion.