• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.174-175
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• 2012

철도 분야에서도 환경 보호 및 에너지 절감을 위한 경량화 연구가 활발히 진행 되고 있다. 본 논문에서는 철도차량의 보조전원장치 경량화에 대해 설명 한다. 기존의 철도차량의 보조전원 장치는 내부 필터 리액터, 변압기 등이 중량의 상당한 부분을 차지 하고 있고, 이는 시스템 중량 저감을 위한 고민에서 가장 큰 위치를 차지 한다. 본 논문에서는 공진형 컨버터를 사용하고 스위칭 주파수를 높여 필터 리액터, 변압기 등을 경량화 하였다. 150kW급 시제품에 대한 모의해석과 실험을 통해 입증 하였다.

• Nuclear Engineering and Technology
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• v.49 no.6
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• pp.1339-1345
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• 2017

In the framework of the EU funded project NURESAFE, the subchannel code CTF and the neutronics code DYN3D were integrated and coupled on the NURESIM platform. The developments achieved during this 3-year project include assembly-level and pin-by-pin multiphysics thermal hydraulics/neutron kinetics coupling. In order to test this coupling, a PWR rod ejection transient was simulated on a MOX/UOX minicore. The transient is simulated using two different models of the minicore. In the first simulation, both codes model the core with an assembly-wise resolution. In the second simulation, a pin-by-pin fuel-centered model is used in CTF for the central assembly, and a pin power reconstruction method is applied in DYN3D. The analysis shows the influence of the different models on global parameters, such as the power and the average fuel temperature, but also on local parameters such as the maximum fuel temperature.

• Journal of the Korean Society of Food Culture
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• v.27 no.1
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• pp.75-81
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• 2012

This study was conducted to investigate the physiological activity of acai berry (Euterpe oleracea Mart.) extracts from three different solvents (water, methanol, and ethanol). We measured total polyphenol and total flavonoid content, DPPH radical scavenging activity, nitrite scavenging activity, metal chelating effect, and reducing power. The extraction yield from water, methanol, and ethanol was 17.10, 9.50, and 37.51%, respectively. The highest total polyphenol content (10.54 mg/100 g) and total flavonoid contents (1.88 mg/100 g) was observed in water extract. DPPH radical scavenging activity was the highest in both water extract (72.03%) and methanol extract (74.79%) at levels of 5 mg/mL, which was similar to that of BHT (78.90%). Water extract yielded the highest metal chelating effect (92.54%) and reducing power (1.09) at levels of 5 mg/mL. Taken together, these findings suggest that extracts of acai berry can be used as functional food materials with antioxidative and nitrite scavenging activities.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.13-14
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• 2016

This paper has introduces a novel Integrated On-board Charger (IOBC) to reduce the size, weight and cost of power conversion stages in Electric Vehicles (EVs). The IOBC is composed of an OBC and a low voltage dc-dc converter (LDC). The IOBC includes a bidirectional ac-dc converter and a bidirectional full-bridge converter with an active clamp circuit. The LDC converter is a hybrid topology combining an active clamped full-bridge converter and a forward converter derived from the Weinburg converter topology. Unlike conventional OBC, the proposed IOBC is compact and the LDC converter of it can achieve a higher efficiency. In addition, the LDC converter of the proposed IOBC can achieve high step-down voltage conversion ratio, no circulating current, no reverse recovery current of the rectifier diodes and small ripple current of output inductor on the auxiliary battery. A 1kW hardware of the LDC converter is implemented to verify the performances of the proposed IOBC.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.62-62
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• 2003

Charged particles can be accelerated to relativistic high energies by high power (＞ terawatt) laser beams. We have a research project on laser and plasma-based advanced accelerators in Center for Advanced Accelerators at Korea Electrotechnology Research Institute (KERI), in which the 2 TW (1.4 J／700 fs) Ti：sapphire／Nd：glass hybrid laser system and a He plasma will be used for particle acceleration experiments. In this presentation, we introduce the ongoing research activities and the planned experiments at KERI.

• Electronics and Telecommunications Trends
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• v.34 no.3
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• pp.86-92
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• 2019

New products and services, such as 5G and wireless power transmission equipment, have recently brought about changes in the field of electromagnetic technology. There is a need for the evaluation and measurement of the health effects of such technology. To address this need, the development of international standards related to human exposure to electromagnetic waves of these new technologies are currently being discussed. This article briefly introduces the International Standard Organization standards for human exposure to electromagnetic waves, and focuses on the major standard trends for SAR measurement techniques that employ vector probes, wireless power transfer, and 5G base station measurement.

• ETRI Journal
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• v.44 no.6
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• pp.885-902
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• 2022

The mmWave cell-free massive MIMO (CFmMIMO), combining the advantages of wide bandwidth in the mmWave frequency band and the high- and uniform-spectral efficiency of CFmMIMO, has recently emerged as one of the enabling technologies for 6G. In this paper, we propose a novel framework for energy-efficient mmWave CFmMIMO systems that uses low-resolution digital-analog converters (DACs) and phase shifters (PSs) to introduce lowcomplexity hybrid precoding. Additionally, we propose a heuristic pilot allocation scheme that makes the best effort to slash some interference from copilot users. The simulation results show that the proposed hybrid precoding and pilot allocation scheme outperforms the existing schemes. Furthermore, we reveal the relationship between the energy and spectral efficiencies for the proposed mmWave CFmMIMO system by modeling the whole network power consumption and observe that the introduction of low-resolution DACs and PSs is effective in increasing the energy efficiency by compromising the spectral efficiency and the network power consumption.

• Journal of environmental and Sanitary engineering
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• v.16 no.2
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• pp.9-16
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• 2001

If a pollutant invade at liguid and gas, it will be use ozone in order to remove or sterilize. Ozone excessively supply in order to receive satisfactory efficiency. If excessive ozone leave like that, second-problem will be occur. This study used high heater in order to treat occurred ozone. ; the results were as follow : 1. As initial ozone os supplied with $1.789{\;}g/m^3$ : For the 40, 50, 60, 70(V) of electric potential $O_3$ removal efficiency was treated 34.41, 73.78, 98.60, 98.97%(time of operation ; after 5min.). 2. As initial ozone is supplied with $3.645{\;}g/m^3$ : For the 40, 50, 60, 70(V) of electric potential, $O_3$ removal efficiency was treated 1.78, 69.27, 99.18, 98.68%(time of operation ; after 5min.). 3. As initial ozone is supplied with $4.759{\;}g/m^3$ : For the 50, 60, 70(V) of electric potential, $O_3$ removal efficiency was treated 61.29, 99.29, 99.18%(Time of operation ; after 5min.). 4. Used electric power is 15.38, 24.00, 35.29, 46.15(w/hr) at the 40, 50, 60, 70(V) of the electric potential. 5. Regarding electric power and $O_3$ removal efficiency, Used electric pote-ntial economized at 60(V).

• Journal of Power System Engineering
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• v.5 no.3
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• pp.80-87
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• 2001

Decorative properties of chromium depositions from oxalic acid bath containing chromium oxide and ammonium sulfate have been examined over a wide range of bath compositions and plating conditions. The obtained results from this experiment are summarized as follow: The followings were determined as a optimum conditions, bath compositions; $CrO_3\;200{\sim}250\;g/{\ell},\;H_2C_2O_4{\cdot}2H_2O\;500{\sim}700\;g/{\ell},\;(NH_4)_2SO_4\;40{\sim}120\;g/{\ell}$, and operation conditions; pH $2.0{\sim}2.5$, current density $15{\sim}250\;A/dm^2$ at bath temperature range of $30{\sim}80^{\circ}C$. Bright chromium deposits were obtained over a wide range of ammonium sulfate concentration and bath temperature. Decorative property for chromium deposition was adopted to apply stoichiometric ratio of $CrO_3$ concentration and $H_2C_2O_4{\cdot}2H_2O$.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.611-614
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• 2003

The rheological properties of exopolysaccharide, p-KG03, produced by marine microalgae Gyrodinium impudicum strain KG03 had been studied. The intrinsic viscosity of this p-KG03 was calculated to 65.22 and 50.75 $d{\ell}/g$ using Huggins and Kramer equations (xanthan gum 24.41 and 24.03). Aqueous dispersions at p-KG03 concentrations ranging from 0.1 to 1.0 % (w/w) showed marked shear-thinning properties as Power-Law behavior. In aqueous dispersions of p-KG03 1.0 %, consistency index (K) and flow behavior index (n) were 2,172 and 0.52. The apparent viscosity and the influence of shear rate on different conditions as p-KG03 concentrations, pH, NaCl, $CaCl_2$ and temperature in aqueous solutions were measured. And p-KG03 had mixed with aqueous solutions of xanthan gum and gellan gum, and invested the change of mixed aqueous solution behavior.