• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.6
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• pp.433-437
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• 2021

As the demand for new and renewable energy increases due to the depletion of fossil fuels, solar power generation, a core energy source for new and renewable energy, requires research on solar modules for high output power generation. In this paper, the electrical characteristics of solar cell strip at the edge and in the center of single-crystal silicon having a semi-square shape were analyzed. The cell strip located in the center showed the efficiency increase by 0.26% compared to the cell strip at the edge of the solar cell. A shingled photovoltaic module was manufactured for each cell strip. As a result, the output power of the module using the cell strip located in the center was higher by 0.992%.

• Korean Journal of Optics and Photonics
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• v.32 no.4
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• pp.147-152
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• 2021

We report high-power continuous-wave operation of a Yb-doped fiber laser at 1070 nm, pumped by high-power laser diodes at 976 nm. Based on theoretical calculation of the stimulated Raman scattering and temperature distribution in the fiber, we construct a bidirectionally pumped Yb-fiberlaser system incorporating a pair of fiber Bragg gratings and a cladding light stripper. The fiber laser yields 3.0 kW of continuous-wave output at 1070 nm in a diffraction-limited beam with M² ≈ 1.26 for 4.1 kW of incident pump power, corresponding to a slope efficiency of 81.5%. The prospects for further power scaling are discussed.

• Journal of Korean Society for Quality Management
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• v.39 no.2
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• pp.244-255
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• 2011

In this study, we try to evaluate the efficiency of the photonics industry using a data envelopment analysis(DEA) model. We first develope four stage procedures for selecting proper input and output variables which consist of selecting the first candidate variables from literature survey, selecting the second candidate variables through experts' discussion, measuring the partial efficiency of the selected variables based on Tofallis' profiling, and clustering some variables through the rank correlation analysis of partial efficiency proposed by Min and Kim(l998). With this procedure, we select 4 input variables(capital, number of employee, R&D cost, operating cost) and 2 output variables(sales, growth of sales) and then utilize CCR and BCC model to measure efficiencies of 26 photonics companies in Gwangju. Moreover, we perform the reference group analysis to figure out what causes inefficiencies and to provide the desirable values for input and output variables at which inefficient photonics companies become efficient. Finally, we classify 26 photonics companies into three groups such as optical communications, optical applications, and optical sources, and perform the Kruskal-Wallis test to check if there exist some differences between efficiencies of three groups.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.12
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• pp.1890-1897
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• 2022

In this paper, we design a navigation filter for an underwater glider. Underwater gliders are low-cost, reusable, and can be used for a long time. Two types of filters are designed considering characteristics such as small size, low cost, and low power. The navigation filter estimates the reference velocity of the underwater glider's body frame based on the minimum sensor output. The sensor configuration of the first filter consists of an accelerometer, a magnetometer, and a depth sensor. the second filter include extra a gyroscope in the same configuration. The estimated velocity is fused with the attitude, converted into the velocity of the navigation frame and finally the position is estimated. To analyze the performance of the proposed filter, analysis was performed using Monte Carlo numerical analysis method, and the results were analyzed with standard deviation (1σ). Standard deviations of each filter's position error are 334.34m, 125.91m.

• Journal of Technology Innovation
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• v.27 no.3
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• pp.1-26
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• 2019

The Korean economy has undergone growth based on manufacturing end products. The Korean government aims to advance industry by strengthening the materials and components industry, which is attracting more attention in terms of maintaining the competitiveness of existing key industries, and fostering new industries required in the era of the Fourth Industrial Revolution. Despite this importance, there is insufficient related research on the efficient R&D of the materials and components industry. This study analyzed the R&D efficiency. In addition, exploratory research was conducted on the impact of corporate size and type of cooperation on R&D efficiency. Output variables were set to reflect economic performance and the empirical analysis revealed that overall R&D efficiency is low. Small firms were found to perform better than large firms in terms of firm-size, and the efficiency of business-university-research cooperation is worse than other types of cooperation. This study is exploratory research considering the materials and components industry, and the results provide implications for research institutions and regarding types of cooperation. This is expected to help develop polices for qualitative growth and R&D strategies for investment and allocation.

• Journal of IKEEE
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• v.26 no.4
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• pp.560-567
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• 2022

This paper proposed an application of agile management method to resolve the electrical system issues identified during the mass production phase of aged aircraft performance improvement. The proposed method was applied from issue analysis to on-site verification and testing stage, before the formal configuration control process. At this time, the project was carried out by setting a sprint period to complete the verification according to requirements through daily scrum and sprint review. As a result, It was verified that the wiring installation of the aircraft, which was the output of the sprint, met requirements within the defined sprint period.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.208-213
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• 2015

The purpose of this study is to optimize the design of a capacitive pressure sensor element using the simulation of electrical characteristics. The simulation of the ceramic sensor diaphragm ($Al_2O_3$) was performed by permitting pressure to change the curvature of the diaphragm. The pressure capacitance ($C_P$) was increased from 19.63 pF to 15.26 pF by applying pressure because the distance between the electrodes has been changed from $30{\mu}m$ to $15{\mu}m$. When the thickness of the diaphragm was changed to 0.46~0.52 mm, a larger capacitance change showed in accordance with the reduced thickness, which means an increase of sensitivity. However, considering the viewpoint of the signal linearity, it was selected for the optimum thickness of the diaphragm to 0.50 mm. The designed sensor element based on simulated results was tested to measure the output characteristics. Comparing of simulated and measured results, there was a margin of error of approximately 2%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.4
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• pp.139-144
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• 2016

Effects of the shape and size of the piezoelectric materials on the performance of tonpilz transducers were studied with a computer simulation using a finite element method (FEM). The diameter and height of the donut-shaped piezoelectric ceramics head mass were changed as variables. And the effect of the stack number was also investigated. Finally, if the piezoelectric ceramics were changed to a piezoelectric single crystal having high piezoelectric constants, how the performances especially, the output power and the TVR transmittance were affected was simulated by FEM. As a result, the output of transducer could be increased to 10 times of PZT-4 with replacement of relaxor single crystal of the same size.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.29-34
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• 2021

For the purpose of Application to the small radar sensor, the MMIC Chips, which are the core component of the W-band, was designed in Korea according to the characteristics of the transceiver and manufactured by 60nm GaN and 0.1㎛ GaAs pHEMT process. The output power of PA is 28 dBm at center frequency of W-band and Noise figure is 6.7 dB of switch and LNA MMIC. Output power and Noise figure of MMIC chips developed in domestic was applied to the transmitter and receiver module through W-band waveguide low loss transition structure design and impedance matching to verify the performance after the fabrication are 26.1~27.7 dBm and 7.85~10.57 dB including thermal testing, and which are close to the analysis result. As a result, these are judged that the PA and Switch and LNA MMICs can be applied to the small radar sensor.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.569-575
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• 2020

In this study, a fuel cell system model for ship power was developed and verified by comparing the experimental results obtained by supplying pure oxygen. To verify the proposed model, the fuel cell output characteristics when oxygen was supplied were compared with those when air was supplied using an air compressor. In addition, the effect of the change in the thermal properties of the fuel cell system on the output of the stack was examined. Within the experimental range of this study, when pure oxygen was supplied as the cathode supply gas, the calculated and experimental voltages and outputs obtained through modeling were almost the same over the entire load range. When air was supplied instead of oxygen for the cathode supply at a constant load of 560 A, each stack voltage was approximately 14 V, the stack output was approximately 8 kW, and the stack efficiency was approximately 3 %. It was confirmed that the overall system efficiency was reduced by approximately 8 %. Among the thermal properties examined in this study, the heat transfer coefficient of the coolant to the stack was found to have the greatest effect on the output of the stack.