• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.9
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• pp.38-46
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• 2000

In this paper, a grating to apply for the optical interconnection is designed using a Genetic Algorithm(GA) as a robust and an efficient schema. A hybrid optical interconnection system architecture is implemented by the liquid crystal panel as a programmable spatial light modulator. As the result of geometrical transformation to obtain the quantitative data for $3{\times}3$ spot beams at CCD array detector by optical experiment truthfully, the mean of beam intensity as a gray level is 202, the maximum value is 225, the minimum value is 186, and a uniformity is quantitatively $1.93{\times}10^{-1}$ similar to simulation result.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1454-1470
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• 2014

This paper propose a new power conditioner topology with intelligent power management controller that integrates multiple renewable energy sources such as solar energy, wind energy and fuel cell energy with battery backup to make best use of their operating characteristics and obtain better reliability than that could be obtained by single renewable energy based power supply. The proposed embedded controller is programmed for maintaining a constant voltage at PCC, maximum power point tracking for solar PV panel and WTG and power flow control by regulating the reference currents of the controller on instantaneous basis based on the power delivered by the sources and load demand. Instantaneous variation in reference currents of the controller enhances the controller response as it accommodates the effect of continuously varying solar insolation and wind speed in the power management. The power conditioner uses a battery bank with embedded controller based online SOC estimation and battery charging system to suitably sink or source the input power based on the load demand. The simulation results of the proposed power management system for a standalone solar/WTG/fuel cell fed hybrid power supply with real time solar radiation and wind velocity data collected from solar centre, KEC for a sporadically varying load demand is presented in this paper and the results are encouraging in reliability and stability perspective.

• ETRI Journal
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• v.45 no.3
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• pp.519-533
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• 2023

This paper implements a simultaneous solar and thermal energy harvesting system, as a hybrid energy harvesting (HEH) system, to convert ambient light into electrical energy through photovoltaic (PV) cells and heat absorbed in the body of PV cells. Indeed, a solar panel equipped with serially connected thermoelectric generators not only converts the incoming light into electricity but also takes advantage of heat emanating from the light. In a conventional HEH system, the diode block is used to provide the path for the input source with the highest value. In this scheme, at each time, only one source can be handled to generate its output, while other sources are blocked. To handle this challenge of combining resources in HEH systems, this paper proposes a method for collecting all incoming energies and conveying its summation to the load via the current mirror cells in an approach similar to the maximum power point tracking. This technique is implemented using off-the-shelf components. The measurement results show that the proposed method is a realistic approach for supplying electrical energy to wireless sensor nodes and low-power electronics.

• Journal of Korean Academy of Nursing
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• v.54 no.3
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• pp.340-357
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• 2024

Purpose: This study aimed to develop a Hybrid Clinical Practicum Environment Scale for Nursing Students (HCPES-NS) and verify its validity and reliability. Methods: The HCPES-NS was constructed following the DeVellis guidelines. The initial items were written based on a literature review and individual in-depth interviews. Content validity was verified through an expert panel review. To confirm the validity and reliability of the scale, a survey was conducted with 449 nursing students enrolled in 12 nursing colleges. Data were analyzed using item analysis, exploratory factor analysis, confirmatory factor analysis, concurrent validity, and reliability tests. Results: Factor analysis showed that the HCPES-NS consists of 15 items on five subdomains: clinical site atmosphere, interpersonal relationship, alternative online practicum contents, provision of learning information, and clinical performance facilitation. A higher score indicated a more positive perception of the clinical practicum environment. The concurrent validity of the HCPES-NS was confirmed by its positive correlation with the Clinical Learning Environment Scale (r = .77). The Cronbach's α reliability of the HCPES-NS was .84. Conclusion: The HCPES-NS is both valid and reliable. This scale reflects the clinical practicum environment and includes an online practicum factor. It may be used effectively by faculty members and educators to evaluate nursing students' perceptions of clinical practicum environments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1099-1107
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• 2013

This study proposes a weight reduction design for urban transit, specifically, a Korean EMU carbody made of aluminum extrusion profiles, according to size optimization and useful material changes. First, the thickness of the under-frame, side-panels, and end-panels were optimized by the size optimization process, and then, the weight of the Korean EMU carbody could be reduced to approximately 14.8%. Second, the under-frame of the optimized carbody was substituted with a frame-type structure made of SMA 570, and then, the weight of the hybrid-type carbody was 3.8% lighter than that of the initial K-EMU. Finally, the under-frame and the roof-panel were substituted with a composite material sandwich to obtain an ultralight hybrid-type carbody. The weight of the ultralight hybrid-type carbody was 30% lighter than that of the initial K-EMU. All the resulting carbody models satisfied the design regulations of the domestic Performance Test Standard for Electrical Multiple Unit.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.3
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• pp.200-210
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• 2019

High-speed planing craft is generally smaller than commercial vessels, for which not only the roll motion but also the pitch and heave motions are relatively large during operation However, if seakeeping performance of high-speed planing craft is evaluated by assessment methods of commercial vessels considering roll damping only, it would get unreasonable results due to excessive magnitudes of motion. This research aims at developing a procedure to evaluate seakeeping performance of high-speed planing craft reasonably well by considering responses of roll, heave and pitch motions. In addition, we tried to combine advantages of the potential flow method and CFD in this procedure, a so-called hybrid method, which uses the 3D panel method for the analysis of seakeeping performance, and tunes the damping coefficient using CFD analysis at a specific frequency. Finally, we evaluated seakeeping performance of coastal rescue boat in operation by applying the proposed procedure, and analyzed the results referring to the seakeeping criteria.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.149-154
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• 2018

This paper describes the fabrication and heat transfer property of 50 watts rated LED array module where multiple chips are mounted on chip-on-board type ceramic-metal hybrid substrate with high heat dissipation property for high power street and anti-explosive lighting system. The high heat transfer ceramic-metal hybrid substrate was fabricated by conformal coating of thick film glass-ceramic and silver pastes to form insulation and conductor layers, using thick film screen printing method on top of the high thermal conductivity aluminum alloy heat-spreading panel, then co-fired at $515^{\circ}C$. A comparative LED array module with the same configuration using epoxy resin based FR-4 PCB with thermalvia type was also fabricated, then the thermal properties were measured with multichannel temperature sensors and thermal resistance measuring system. As a result, the thermal resistance of the ceramic-metal hybrid substrate in the $4{\times}9$ type LEDs array module exhibited about one third to the value as that of FR-4 substrate, implying that at least triple performance of heat transfer property as that of FR-4 substrate was realized.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.4
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• pp.374-382
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• 2014

This paper presents the computational aerodynamic analysis of a long-endurance UAV that was developed by the Korea Aerospace Research Institute (KARI), named EAV-2. EAV-2 is a technical demonstrator of aerodynamically efficient design, as well as a hybrid electric-propulsion system for future long-endurance UAVs. We evaluated the aerodynamic characteristics of six low-Reynolds number airfoils, using a panel method code, XFOIL, to select an optimal airfoil for the long-endurance mission of EAV-2. The computational results by a CFD code, FLUENT, suggested that the aerodynamic performance of EAV-2 would be notably improved after adopting SG6043 airfoil, and modifying the fuselage design. This reduced the total drag by 43%, compared to that of a previous KARI model, EAV-1, at the target lift of $C_L=1.0$. Also, we achieved a drag reduction of approximately 14% by means of the low-drag fuselage configuration.

• Electronics and Telecommunications Trends
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• v.22 no.5
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• pp.95-107
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• 2007

X-선 측정 및 영상장치를 포함한 다양한 응용분야에서 방사선에 대한 고해상도의 영상을 얻기 위한 목적으로 반도체 검출기에 대한 개발이 활발히 진행되고 있다. 본 고에서는 방사선 검출을 위해 요구되는 반도체 물질의 주요 특성에 대해서 조사하였다. 또한 반도체를 이용한 플랫 패널(flat panel) 시스템, 픽셀 디텍터(pixel detector)와 스트립 디텍터(strip detector) 등의 혼성형 디텍터(hybrid detector), MAPS와 DEPFET 등의 단일형 픽셀 디텍터(monolithic pixel detector)의 디바이스 동작 원리 및 특성과 국내외 기술 동향에 대하여 살펴보았다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.6
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• pp.602-608
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• 2014

Mixed-model production lines are often used in manufacturing systems. In production lines, different product types are simultaneously manufactured by processing small batches. This paper describes a new welding assembly technology involving the development of experimental models for a mixed-model production line in an automobile company. Due to the extensive number of models, the design of a welding assembly system is complicated. Performance evaluation is an important phase in the design of welding assembly lines in a mixed-model production environment. In this study, a new welding assembly technology for a mixed-model production method was used to weld the package tray and dash panel of a vehicle.