• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.47-49
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• 2019

본 논문은 노화로 인하여 감소하는 전기자동차용 배터리의 전류 용량을 실시간으로 추정하는 SOH (State-of-health) 알고리즘을 제안한다. 제안하는 알고리즘은 노화에 따른 OCV (Open circuit voltage) 곡선의 변화 경향을 분석하고, 저주파 통과 필터를 이용하여 추정된 OCV를 기반으로 전류 용량 및 SOH를 산출한다. 알고리즘을 검증하기 위하여 전기자동차용 배터리를 이용한 실험 및 시뮬레이션을 진행한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.4
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• pp.241-248
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• 2021

A battery state-of-health (SOH) estimation algorithm using a machine learning-based linear regression method is proposed for estimating battery aging. The proposed algorithm analyzes the change trend of the open-circuit voltage (OCV) curve, which is a parameter related to SOH. At this time, a section with high linearity of the SOH and OCV curves is selected and used for SOH estimation. The SOH of the aged battery is estimated according to the selected interval using a machine learning-based linear regression method. The performance of the proposed battery SOH estimation algorithm is verified through experiments and simulations using battery packs for electric vehicles.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.477-480
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• 2015

In this paper a low-voltage vibration energy harvesting circuit with MPPT(Maximum Power Point Tracking) control is proposed. By employing bulk-driven technique, the minimum operating voltage of the proposed circuit is as low as 0.8V. The designed MPPT control circuit traces the maximum power point by periodically sampling the open circuit voltage of a full-wave rectifier circuit connected to the piezoelectric device output and delivers the maximum available power to load. The proposed circuit is designed using a $0.35{\mu}m\;CMOS$ process, and the chip area including pads is $1.33mm{\times}1.31mm$. Simulation results show that the maximum power efficiency of the designed circuit is 85.49%.

• Journal of the Korean Society of Safety
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• v.28 no.2
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• pp.26-30
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• 2013

The purpose of this study is to find risk factors by analyzing the operation principle of a photo coupler (P/C) used to remove the noise of electronic devices and establish a base for the performance improvement of developed products. It was found from the P/C circuit analysis of normal products that they were equipped with an electrolytic condenser of $0.1{\mu}F$ to smooth system signals. Due to the epoxy resin packing the external part of the P/C, this study experienced a limit to visually examine the damage to it. It could be seen from the analysis of electric characteristics of the P/C that the forward voltage ($V_f$) and reverse current ($I_r$) were 1.3 V and 10 uA, respectively. In addition, it is required that the breakdown voltage (VCE) between the collector (C) and emitter (E) be maintained at less than 35 V. The and of the damaged product #1 were comparatively good. However, the measurement of was 100.0 uA. From this, it is thought that a short circuit occurred to the internal circuit. Moreover, from the fact that the of the damaged product #2 was open circuit and the measurement of was 0.0 uA, it is thought that the collector and emitter was separated or insulation resistance was significantly high. Furthermore, from the fact that the of the damaged product #3 was open circuit and the measurement of was 0.0 uA, it is thought that the space between the collector (C) and emitter (E) failed to meet the design standard or that they were separated. Therefore, it is thought that fabricating the P/C by increasing the reverse current 10 mA to 50 mA will prevent its malfunction.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.89.1-89
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• 2003

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.917-922
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• 2012

In order to improve applicability of a microbial fuel cell the laboratory-scaled study has been performed by adopting an air-cathode MFC system with high concentrated anaerobic slugies in this study. The concentrations of microbes are grouped into three types, Type A (TS 1.7%), Type B (TS 1.1%) and Type C (TS 0.51%). The open circuit voltage $(V_{oc})$ characteristics showed that the medium microbes concentration of 1.10% (Type B) kept a constant voltage of 1.0 V for 150 hours, which showed the longest time among three types (Type A and Type C). The discharge charge curves for a closed circuit with $500 \Omega$ also showed that Type B generated a stable discharge voltage of 0.8 V for a longer time as in the open circuit voltage case. This could be explained by the relatively large amount of the attached microbes. Under the $V_{oc}$condition the COD removal efficiency of Type B was found to be low for a long time, but those of Type A and C were found to be high for a short period of time. Therefore, the suspended microbes could decrease the coulombic efficiency. It was concluded that the high $V_{oc}$ was caused by low COD and the $V_{oc}$ became low after the COD removal. The COD reduction resulted in an unstable and low working voltage. From the polarization characteristics Type A was found to show the highest power density of $193\;mW/m^2$ with a fill factor of 0.127 due to the relatively high remaining COD even after the MFC reaction.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.523-528
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• 1998

The electrochemical characteristics of $V_2O_5$ as working electrode were studied in the cell (1-butene+$O_2$, $V_2O_5{\mid}YSZ{\mid}Ag$, $O_2$) with a YSZ solid electrolyte. The sintering of Ag as a counter electrode was occurred after calcination, and the structure which has the pores of over $3{\mu}m$ was achieved. In particular, the peak of (010) plane of the working electrode on the XRD spectrum which is responsible for selective oxidation appeared after calcination. The major product of 1-butene oxidation over $V_2O_5$ was butadiene. The technique of SEP (solid electrolyte potentiometry) was used to monitor the chemical potential of chemical species adsorbed on the working electrode. Over a wide range of gas compositions of 1-butene and oxygen, open circuit voltage (OCV) exhibited the mixed potential of surface oxygen activity.

• Transactions on Electrical and Electronic Materials
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• v.10 no.4
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• pp.143-145
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• 2009

The electrical and photovoltaic properties of single junction silicon quantum dot solar cells are investigated. A prototype solar cell with an effective area of 4.7 $mm^2$ showed an open circuit voltage of 394 mV and short circuit current density of 0.062 $mA/cm^2$. A diode model with series and shunt resistances has been applied to characterize the dark current-voltage data. The photocurrent of the quantum-dot solar cell was found to be strongly dependent on the applied voltage bias, which can be understood by consideration of the conduction mechanism of the activated carriers in the quantum dot imbedded material.

• Journal of Power Electronics
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• v.12 no.1
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• pp.208-214
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• 2012

This paper presents a novel approach based on the loci of instantaneous symmetrical components called "Wing Shape" which requires the measurement of three input stator currents and voltages to diagnose interturn insulation faults in three phase induction motors operating under different loading conditions. In this methodology, the effect of unbalanced supply conditions, constructional imbalances and measurement errors are also investigated. The sizes of the wings determine the loading on the motor and the travel of the wings while their areas determine the degree of severity of the faults. This approach is also applied to detect open circuit faults or single phasing conditions in induction motors. In order to validate this method, experimental results are presented for a 5 hp squirrel cage induction motor. The proposed technique helps improve the reliability, efficiency, and safety of the motor system and industrial plant. It also allows maintenance to be performed in a more efficient manner, since the course of action can be determined based on the type and severity of the fault.

• New & Renewable Energy
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• v.2 no.3
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• pp.31-36
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• 2006

Superstrate pin amorphous silicon thin-film(a-Si:H) solar cells are prepared on $SnO_2:F$ and ZnO:Al transparent conducting oxides(TCO) in order to see the effect of TCO/p-layers on a-Si:H solar cell operation. The solar cells prepared on textured ZnO:Al have higher open circuit voltage VOC than cells prepared on $SnO_2:F$. Presence of thin microcrystalline p-type silicon layer(${\mu}c-Si:H$) between ZnO:Al and p a-SiC:H plays a major role by causing improvement in fill factor as well as $V_{OC}$ of a-Si:H solar cells prepared on ZnO:Al TCO. Without any treatment of pi interface, we could obtain high $V_{OC}$ of 994mV while keeping fill factor(72.7%) and short circuit current density $J_{SC}$ at the same level as for the cells on $SnO_2:F$ TCO. This high $V_{OC}$ value can be attributed to modification in the current transport in this region due to creation of a potential barrier.