• Korean Journal of Optics and Photonics
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• v.33 no.6
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• pp.260-266
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• 2022

A diffraction grating structure composed of two matching layers and two grating layers was formed, and a diffraction grating with high transmission diffraction efficiency in the -1st order was designed through an optimization technique. The designed diffraction grating had a transverse electric wave diffraction efficiency of 99.997% at the design center wavelength, and had a wavelength width of 80 nm and an incident angle width of 20.0° that maintained a diffraction efficiency of 95% or more. By performing the grating tolerance analysis, it was confirmed that the thickness tolerance for a diffraction efficiency of 95% or more was secured to at least 60 nm, and the diffraction efficiency could be maintained even in a trapezoidal shape with an internal angle of less than 10°.

• Journal of Korean Society for Quality Management
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• v.46 no.3
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• pp.551-568
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• 2018

Purpose: This study addressed the relationship between technological innovation activity and management efficiency of Korean automobile firms. We tested the hypothesis of non-liner relationship of innovation activity in relation to management efficiency. Methods: We discussed prior literature in the firm innovation strategy and management efficiency studies to provide better understanding of relationships between technological innovation activity and management efficiency. As a result, we developed develop and tested a model (Inverted-U shaped) capturing the non-linear impact of technological innovation activity. While we used R&D expenditure and patent registration data for measuring firms' innovation activity, management efficiency was evaluated by using DEA(Data Envelopment Analysis). Results: Main findings of our empirical analysis indicated that the relationships between technological innovation activity and management efficiency was inverted U shaped. This implied that the relationship between technological innovation and management efficiency is inverted U-shaped non-linear, with management efficiency increasing up to a point, beyond which higher levels of R&D and patent registration activities led to a decrease in management efficiency. Conclusion: This study empirically assessed the inconclusive findings of previous research in the area of effects of innovation activities in relation to firm performance. The paper also provided theoretical and practical implications for firms who explore efficient strategy to promote the management performance through technological innovation activities. Future research directions with the limitation of the study was discussed.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.1
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• pp.13-19
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• 2017

Relatively low efficiency in anaerobic digestion process is mainly caused by unproper mixing method. In this study, tray motion type agitator was applied in actual anaerobic digestion tank in order to improve the digestion efficiency, equalize the flow velocity distribution and energy saving. The impeller of tray motion type agitator was reciprocated vertically. Gas lift type agitator and tray motion type agitator appears almost same mixing efficiency include digestion rates. However, tray motion type agitator have shown that lower energy consumption compared to the conventional gas lift type agitator. Implementation of tray motion type agitator in the anaerobic digestion tanks contributed to the stabilization of mixing environment, efficiency and energy efficiency of the tank.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1125-1131
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• 2013

Wireless power transmission technology has been studied variety. Recently, wireless power transmission technology used by resonance and magnetic induction field is applied to various fields. However, magnetic resonance and inductive coupling are have drawbacks - power transmission distance is short. Microwave transmission and accept techniques have been developed to overcome short distance. However, improvement in efficiency is required. This paper, propose a high-efficiency microwave energy acceptor IC(EAIC). Suggested EAIC is consists of RF-DC converter and DC-DC converter. Wide Input power range is -15 dBm ~ 20 dBm. And output voltage is boosted up to 5.5 V by voltage boost-up circuit. EAIC can keep the output voltage constant. Available efficiency of RF-DC converter is 95.5 % at 4 dBm input. And DC-DC efficiency is 94.79 % at 1.1 mA load current. Fully EAIC efficiency is 90.5 %.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.9-14
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• 2000

In this study, the removal efficiencies of organics, nitrogens and phosphorus from municipal wastewater using $A^2$/O process were investigated. BO $D_{5}$ removal efficiencies were indicated 95% and 94% with HRT of 12 hr and 10 hr, respectively. CO $D_{Cr}$ average removal efficiency and concentration of effluent were indicated 87% and 34mg/$\ell$. SS average removal efficiency and concentration of effluent were indicated 93% and 4~17mg/$\ell$. T-N removal efficiency and concentration of effluent were shown as 60~80% and below 15mg/$\ell$. In aerobic basin, removal efficiency of N $H_4$-N was shown over 97% with N $H_4$-N volume load 0.16kg N $H_4$-N/㎥.d and in anoxic basin, denitrification efficiency was indicated over 80% with return sludge rate 0.5Q and internal recirculation rate 2.5Q. Removal efficiency and effluent concentration of phosphorus were shown over 80% and below 2 mg/$\ell$ with return sludge rate 0.5Q.Q.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.256-256
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• 2009

This paper presents a proper condition to achieve above 17 % conversion efficiency using PC1D simulator. Crystalline silicon wafer with thickness of $240{\mu}m$ was used as a starting material. Various efficiency influencing parameters such as rear surface recombination velocity and minority carrier diffusion length in the base region, front surface recombination velocity, junction depth and doping concentration in the Emitter layer. Among the investigated variables, we learn that 2nd doping concentration as a key factor to achieve conversion efficiency higher than 17 %.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.4
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• pp.47-52
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• 1998

As to power combining system, it is very important to achieve a high combining efficiency in order to minimize theamount of prime power needed and hence the cooling requirements, all of which translate into reduced cost. The combining efficiency is degraded in practice by variation in the amplitude and phase of the signals to be combined. In this paper, the new power combining newtork is proposed and realized which has the automatic gain and phase control system. This control system makes amplituede and phase variation of its all path equal. When the amplitude and phase variations are within 0~5dB and .+-.50.deg., the results show that high combining efficiency is maintained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.15-18
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• 2001

Perdeuterated hexaflouroacetylacetonato-ytterbium [Yb(SOL)-D)$_3$] complexes were synthesized by the keto-enol tautomerism reaction of Yb(SOL-H)$_3$ in methanol-d$_4$in methanol-d$_4$in order to reduce the radiationless transition to the ligands. The luminescence properties of Yb(SOL-D)$_3$complex were measured in the following anhydrous deuterated organic solvents ; Methanol-d$_4$, THF-d$\sub$8/, PO(OCH$_3$)$_3$ and DMSO-d$\sub$6/. The intensity, lifetime and quantum efficiency of the luminescence in DMSO-d$\sub$6/ were superior to those in other deuterated solvents. It was suggested that the anhydrous DMSO-d$\sub$6/ might be the most appropriate solvent for the liquid laser material of Yb(SOL-D)$_3$ complex.

• International Area Studies Review
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• v.20 no.2
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• pp.63-83
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• 2016

This paper examines the determinants of efficiency in a KOSDAQ-listed manufacturing firm. We use Data Envelopment Analysis (DEA) to estimate the efficiency of the export manufacturing firm. We employ two inputs (number of employees, equity) and one output (sales) in the DEA. The determinants of export manufacturing firm efficiency are estimated using the panel Tobit model. An analysis of 369 export manufacturing firms from 2013 to 2015 indicates the following results: First, the R&D intensity, the wage and salary intensity, total asset, and equity ratio each had a negative impact on both the CCR and BCC efficiency scores. However, export intensity had a negative impact on CCR efficiency scores in a KOSDAQ-listed total export manufacturing firm. Second, the R&D intensity had a positive impact on both the CCR and BCC efficiency scores, but export intensity, the wage and salary intensity, and equity ratio each had a negative impact on the CCR and BCC efficiency scores in a KOSDAQ-listed large export manufacturing firm. Third, the R&D intensity, the wage and salary intensity, total asset, and equity ratio each had a negative impact on both the CCR and BCC efficiency scores; respectively, in a KOSDAQ-listed small and medium export manufacturing firm.

• Journal of Environmental Health Sciences
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• v.11 no.2
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• pp.17-27
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• 1985

The objectives of this study is to examine efficiency of swinery wastewater treatment by trickling filters' pilot plant. The results of this study are as follows: 1. The characteristics of sample. The BOD$_5$ was from 2,450 to 2,880mg/l, COD(KMnO$_4$ acid method) was from 910 to 1,064mg/l, and SS was from 920 to 990mg/l. The pH of influent was from 7.3 to 7.6, and the temperature of water was from 17.0$\circ$C to 22.5$\circ$C. 2. For experiment by recirculation, the BODs removal efficiency is 65.2% at recirculation ratio (r)=0, and 70.7% at r=1. The ramoval efficiency of this study is higher than NRC formula of U.S.A.. The recirculation is not significant effect on removal efficiency. 3. For experiment by hydraulic load, the BOD$_5$ removal rate decreased from 73.1% at $3.1m^3/m^2\cdot d$ to 65.3% at $9.2m^3/m^2\cdot d$. The design formula of this study which shows the removal rate of soluble BOD is $Le/Li =10^{-0.24} D/Q^{0.24}$ (Q: hydraulic load, D: depth of filter). 4. For experiment by organic load, the BOD$_5$ removal rate is increased from 70.2% at $0.77kg/m^3\cdot d$ to 75.4% at $4.28kg/m^3\cdot d$. We can obtain the straight line y=0.749 x (y: removed BOD, x :applied BOD) by the least squares method. 5. We can know that trickling filters is strong with the hydraulic load and the organic matter shock load. Here, we can judge that trickling filters is a good method for the treatment of swinery wastewater which containing high concentrated organic matter.