• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.131-133
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• 1995

Inductive high-Tc superconducting fault current limiter using YBCO superconducting ring in the secondary part has many advantages in power networks. It is based on the superconducting to normal transition and this paper describes its operational characteristics and experimental results, especially focused on the harmonic component analysis and recovery time. We fabricated and tested it under various conditions for the analysis of transient fault characteristics. And for the analysis of harmonics we used FFT methods. The superconducting ring was quenched in 240Arms and fault current was effectively limited to the lower current level. In addition, it was fast recovered when the fault condition was removed and after fault the system had odd harmonics.

• 한국정밀공학회지
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• 제17권8호
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• pp.140-150
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• 2000

In this paper module of a product is determined by the characteristics of a product itself and process. To analyze the characteristics of the product information on subassemblies and parts can be obtained by analyzing the existing product. Based on the analysis of characteristics of product structure and function determination rules of a module degree could be proposed for assembly and disassembly process and product structure and function. By applying these rules of a module, module of a product is classified into full half and non-module depending on the module degree of a product. As a result of module degree analysis simpler assembly process and reduced structural interference can be realized. For the product function simpler updated and multi function can be also achieved.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권6호
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• pp.951-963
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• 2015

The water wave characteristics of Bragg reflections from a train of fixed floating pontoon breakwaters was studied numerically. A numerical model of boundary discretization type was developed to calculate the wave field. The model was verified by comparing to analytical data in literature and good agreements were achieved. Series of parametric studies were conducted systematically to investigate the dependence of the reflected coefficients by the Bragg scattering on the design variables, including the spacing between the breakwaters, the total number of installed breakwaters, the draft and width do the breakwater, and wave length. Certain wave characteristics of the Bragg reflections were observed and discussed in details which might be of help for practical engineering applications in shoreline protection from incident waves.

• 전기학회논문지
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• 제68권1호
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• pp.36-43
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• 2019

In this paper, the characteristics of the coaxial magnetic gear according to the shape of the same gear ratio are analyzed using the two - dimensional finite element analysis. The rotor shape is SMCMG, CPCMG and RCMG. After this we analyzed the characteristics according to three shapes. Also, the amount of permanent magnet used in each shape was compared. Next, characteristics analysis of the magnetic gear according to the shape at the same torque was performed. And the total weight and efficiency of the magnetic gears were compared and verified.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.244-255
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• 2019

Interest in renewable energy has been increasing in recent years for many reasons, and there have been many studies on new types of wave energy converters and mechanisms for them. However, in this paper, motion characteristics of a wave energy converter with a wave activating body type is studied with an experiment. In order to conduct the experiment, a simple wave activating body type's wave energy converter is proposed. Experimental variations consist of connection type and location. The connection type controls the rotation motions of structures, and the connection location controls the distance between structures. The movement of floating structures, such as rotation, velocity, and acceleration, is measured with a potentiometer and a motion capture camera. Using the recorded data, the motion characteristics derived from the experimental variations are investigated.

• 항공우주시스템공학회지
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• 제15권4호
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• pp.7-10
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• 2021

Including 425 Program, which is Korean military surveillance and reconnaissance satellite, there were mostly civil-driven space programs in Korea. However, there are increasing numbers of military demand-driven space program in nowadays. Furthermore, it is positive effects on launch vehicle development in Korea that the termination of Korea-U.S. missile guideline. In this paper, it emphasizes the needs of system engineering(SE) management method which meets both defense system's characteristics and space's characteristics. These characteristics are such as non-fixable after the launch, the security issue in defense system. And it also introduces SE tool, methodology and its philosophy. There are several functions that data management, issue management, risk management, and technical requirement management. Also describing its implications and direction of improvement.

• ETRI Journal
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• 제34권6호
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• pp.911-921
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• 2012

In high-speed wireless communications, an analysis of the propagation characteristics is an important process. Information on the propagation characteristics suitable for each environment significantly helps in the design of mobile communications. This paper presents the analysis results of radio propagation characteristics in outdoor environments for a new mobile wireless system at 781 MHz. To avoid the interference of Korean DTV broadcasting, we measure the channel characteristics in urban, suburban, and rural areas on Jeju Island, Republic of Korea, using a channel sounder and $4{\times}4$ antenna. The path loss (PL) measurement results differ from those of existing propagation models by more than 10 dB. To analyze the frequency characteristics for Korean propagation environments, we derive various propagation characteristic parameters: PL, delay spread, angular spread, and K-factor. Finally, we verify the validity of the measurement results by comparing them with the actual measurement results and 3D ray-tracing simulation results.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.472-477
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• 2017

In this work, the current limiting and recovery characteristics of a flux-lock type superconducting fault current limiter (SFCL) with series connection of two coils were effectively improved by adding a third winding into the conventional flux-lock type SFCL with series connection of two coils. To confirm the contribution of the third winding to the current limiting and recovery characteristics of this type of the SFCL, short-circuit testing was carried out with consideration of the third winding, and the effect of the third winding on the current limiting and recovery characteristics was examined by comparative analysis of the amplitude of the limited fault current and the power burden of the high-TC superconducting (HTSC) element comprising the SFCL. Through the analysis of both the limiting impedance and the operational current as the main design parameter of the SFCL, the improved current limiting and recovery characteristics of the flux-lock type SFCL using the third winding could be verified.

• 품질경영학회지
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• 제46권3호
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• pp.677-694
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• 2018

Purpose: The purpose of this study is to investigate various prior studies on artificial intelligence and to examine the concept and characteristics of various prior studies of existing service quality. And this paper is to study the concept and characteristics of artificial intelligence services and propose suitable quality measurement items. Methods: The research method of this paper is to examine previous research related to existing artificial intelligence and to analyze characteristics related to service quality. Results: This paper examines the concept and characteristics of artificial intelligence service in a new era by examining previous studies related to artificial intelligence and derives quality measurement items. Conclusion: In the future, it is necessary to verify the validity of the quality measurement items of artificial intelligence service. Therefore, it is necessary to elicit and verify the main quality measurement items through the investigation of the expert group.

• Tribology and Lubricants
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• 제33권4호
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• pp.148-152
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• 2017

The feel of writing is important to customers when they buy smart devices with stylus such as smartphones and tablet computers. With an aim to reproduce the tactile sensibility of writing instruments when people write on the glass display using a stylus, this study focuses on the frequency characteristics of writing instruments that can describe the vibrations of writing instruments sliding over counter surfaces. In addition, this study includes the effect of various factors influencing the friction of writing instruments such as lubricant, nib material, and contact type. We perform sliding experiments with six types of writing instruments and a sheet of paper to understand the relation between the friction conditions of the nib and the frequency characteristics. As this research focuses on the tactile perception of human skin when people use a writing instrument, the analysis of frequency characteristics is performed in the perceptible frequency range of mechanoreceptors in the human skin. As a result, three types of frequency characteristics are identified. Low frequency peaks are observed for a metal nib with ink; high frequency peaks are observed for a nib without ink; and, middle frequency peaks with a wide range of distribution occurs for fabric nibs with ink. Therefore, to implement the proper feel of writing, at least three types of vibrations have to be made.