• Archives of design research
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• v.14
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• pp.63-74
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• 1996

By study the basic elements and the development process of the visual identity design, We have the aims in this study to help the design study groups in the country to develop a VI design system with a high degree of efficiency. We clarified the strategic position which the individual basic elements occupy in the visual communication process, by studying the individual function and the character of the basic elements which construct the keynote of VI design system, and the mutual relations among them. Also, we presented in this study the systematic and resonable approaching means in the design development process for the VI system with a high degree of efficiency.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.10
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• pp.799-805
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• 1991

In this paper, the analysis and design of a spirally slotted array antenna with high efficiency are presented. Electric fields in the slots are calculated by electromagnetic fields in the upper waveguide and radiation field equations are derived. Slots are arrayed spirally on the upper circular plate of twofold radial waveguide. In order to suppress grating lobes from the array, a slow wave structure is inserted in the upper waveguide. This antenna is characterized by a good circular polarization, high efficiency of 75 percent and grating lobes below -34dB.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.159-160
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• 2015

Recently, it is increased to use the portable device with small size. It is also increasing for demand of a small size adapter. To reduce the size of components, switching frequency has to be increased. But it causes higher switching loss and temperature of components. Especially, the temperature of adapter must be limited because adapter can be easily touched when portable device is being charged. To reduce temperature of adapter, high efficiency is essential. To solve this problem, this paper proposes design of resonance frequency optimization for LLC converter with high efficiency and low temperature of passive components.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.10
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• pp.1371-1376
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• 2014

In this paper, 4-phase switched reluctance motor(SRM) with 8-stator and 6-rotor pole structure is proposed for a high speed fan with a low voltage. The air blower has unidirectional rotation characteristics and requires a low torque ripple and noise as well as high efficiency. To achieve the requirements, voltage and current according to loading condition of limited specification is considered. Design process is to select the bore diameter, pole arc, york of stator and rotor to get a high torque and efficiency. To verify the validity of the proposed structure, finite element method(FEM) is employed to get the performances. And the converter for the proposed SRM is employed a 1.5q power converter for cost effectiveness. Prototype SRM is manufactured and tested, and the test results show this design is within the specification and good for the air blower applications.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.86-88
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• 2003

The efficiency of electric machine is important due to increase of interest about energy saving. Single Phase Line Start Permanent Magnet Synchronous Motor has high efficiency and power factor. LSPMSM offer a high efficiency as compared induction motor which are used in the home appliance. The analysis and design of LSPMSM is difficult because of unbalanced rotating magnetic field, nonlinear characteristics and rotor saliency. To consider these effects, F.E.M(Finite Element Methods) is coupled equivalent circuit methods. In this paper, a methods of analysis and design using F.E.M and equivalent circuit is represented.

• Current Optics and Photonics
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• v.6 no.5
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• pp.463-472
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• 2022

At certain wavelengths, single-pixel imaging is considered to be a solution that can achieve high quality imaging and also reduce costs. However, achieving imaging of complex scenes is an overhead-intensive process for single-pixel imaging systems, so low efficiency and high consumption are the biggest obstacles to their practical application. Improving efficiency to reduce overhead is the solution to this problem. Salient object detection is usually used as a pre-processing step in computer vision tasks, mimicking human functions in complex natural scenes, to reduce overhead and improve efficiency by focusing on regions with a large amount of information. Therefore, in this paper, we explore the implementation of salient object detection based on single-pixel imaging after a single pixel, and propose a scheme to reconstruct images based on Fourier bases and use U²Net models for salient object detection.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.77-83
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• 2020

A uniflow cyclone has simple structure with a single channel in one direction. The one directional particle removal enables the uniflow cyclone to have compact size and low pressure drop. However, it has low collection efficiency compared to conventional cyclones. In this study, the effect of primary geometry on the performance of a uniflow cyclone with swirl vane is numerically investigated for the design of high performance uniflow cyclone. It is found that as the vortex finder diameter is increased, the pressure drop and the collection efficiency are decreased. Also, the same trend is predicted when the vortex finder height is increased. The best collection efficiency is predicted to be obtained when the vortex finder height is equal to the diameter of a cyclone. Reducing the body height by half will increase the pressure drop by 41%. When the body height is decreased, the collection efficiency is first increased and then decreased. The best collection efficiency is obtained when the body height is 4~5 times the cyclone diameter. Overall, the particle collection efficiency is highest when the Dν/D is equal to 0.3. But, the pressure drop is as high as 1592 Pa. Considering both collection efficiency and pressure drop, the best design is when Dν/D, Hν/D, and Hb/D are equal to 0.5, 1, and 5, respectively.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1540-1554
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• 2023

To use nuclear energy sustainably, spent nuclear fuel, classified as high-level radioactive waste and inevitably discharged after electricity generation by nuclear power plants, must be managed safely and isolated from the human environment. In Korea, the land area is limited and the amount of high-level radioactive waste, including spent nuclear fuels to be disposed, is relatively large. Thus, it is particularly necessary to maximize disposal efficiency. In this study, a high-efficiency deep geological repository concept was developed to enhance disposal efficiency. To this end, design strategies and requirements for a high-efficiency deep geological repository system were established, and engineered barrier modules with a disposal canister for pressurized water reactor (PWR)-type and pressurized heavy water reactor type Canada deuterium uranium (CANDU) plants were developed. Thermal and structural stability assessments were conducted for the repository system; it was confirmed that the system was suitable for the established strategies and requirements. In addition, the results of the nuclear safety assessment showed that the radiological safety of the new system met the Korean safety standards for disposal of high-level radioactive waste in terms of radiological dose. To evaluate disposal efficiency in terms of the disposal area, the layout of the developed disposal areas was assessed in terms of thermal limits. The estimated disposal areas were 2.51 km² and 1.82 km² (existing repository system: 4.57 km²) and the excavated host rock volumes were 2.7 Mm³ and 2.0 Mm³ (existing repository system: 4.5 Mm³) for thermal limits of 100 ℃ and 130 ℃, respectively. These results indicated that the area and the excavated volume of the new repository system were reduced by 40-60% compared to the existing repository system. In addition, methods to further improve the efficiency were derived for the disposal area for deep geological disposal of spent nuclear fuel. The results of this study are expected to be useful in establishing a national high-level radioactive waste management policy, and for the design of a commercial deep geological repository system for spent nuclear fuels.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1891-1901
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• 2017

In this paper, optimal control of the fuel cell and design of a high-efficiency power converter is implemented to build a high-priced fuel cell system with minimum capacity. Conventional power converter devices use a non-isolated boost converter for high efficiency while the battery is charged, and reduce its conduction loss by using MOSFETs instead of diodes. However, the efficiency of the boost converter decreases, since overshoot occurs because there is a moment when the body diode of the MOSFET is conducted during the dead time and huge loss occurs when the dead time for the maximum-power-flowing state is used in the low-power-flowing state. The method proposed in this paper is to adjust the dead time of boost and rectifier switches by predicting the power flow to meet the maximum efficiency in every load condition. After analyzing parasite components, the stability and efficiency of the high-efficiency boost converter is improved by predictive compensation of the delay component of each part, and it is proven by simulation and experience. The variation in switching delay times of each switch of the full-bridge converter is compensated by falling time compensation, a control method of PWM, and it is also proven by simulation and experience.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.120-124
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• 2001

A new technique for improving the efficiency of single-phase high-frequency boost converter is proposed. This converter includes an additional low-frequency boost converter which is connected to the main high-frequency switching device in parallel. The additional converter is controlled at lower frequency. Most of the current flows in the low-frequency switch and so, high-frequency switching loss is greatly reduced accordingly Both switching device are controlled by a simple method; each controller consists of a one-shot multivibrator, a comparator and an AND gate. The converter works cooperatively in high efficiency and acts as if it were a conventional high-frequency boost converter with one switching device. The proposed method is verified by simulation. This paper describes the converter configuration and design, and discusses the steady-state performance concerning the switching loss reduction and efficiency improvement.