• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.11a
• /
• pp.149-150
• /
• 2006

A ZnO nanowire-based FET is fabricated m this study on a flexible substrate of PES. For the flat and bent flexible substrates, the current ($I_D$) versus drain-source bias voltage ($V_{DS}$) and $I_D$ versus gate voltage ($V_G$) results are compared. The flat band was Ion/Ioff ratio of ${\sim}10^7$, a transconductance of 179 nS and a mobility of ~10.104 cm2/Vs at $V_{DS}$ =1 V. Also bent to a radius curvature of 0.15cm and experienced by an approximately strain of 0.77 % are exhibited an Ion/Ioff ratio of ${\sim}10^7$, a transconductance of ~179 nS and a mobility of ${\sim}10.10 cm^2/Vs$ at $V_{DS}$ = 1V. The electrical characteristics of the FET are not changed very much. although the large strain is given on the device m the bent state.

• Nuclear Engineering and Technology
• /
• v.54 no.8
• /
• pp.2871-2876
• /
• 2022

The sensitivity of polymer-based capacitive relative humidity (RH) sensors after irradiation with neutrons, electrons and protons was measured. Degradation consists of the decreasing of the upper RH limit that can be measured. At the same time, low RH-level sensitivity is almost stable. After 30 krad of absorption dose, RH cut off is equal to 85% of max value, after 60 krad-40%. Degradation reduces after annealing which indicates high radiation sensitivity of the internal circuit in comparison to RH-sensing polymer film.

• Current Photovoltaic Research
• /
• v.10 no.3
• /
• pp.77-83
• /
• 2022

Renewable energy is receiving attention again as a way to realize carbon neutrality to overcome the climate change crisis. Among renewable energy sources, the installation of Photovoltaic is continuously increasing, and as of 2020, the global cumulative installation amount is about 590 GW and the domestic cumulative installation amount is about 17 GW. Accordingly, O&M technology that can analyze the power generation and fault diagnose about PV plants the is required. In this paper, a study was conducted to diagnose fault using I-V curves of PV strings and deep learning. In order to collect the fault I-V curves for learning in the deep learning, faults were simulated. It is partial shade and voltage mismatch, and I-V curves were measured on a sunny day. A two-step data pre-processing technique was applied to minimize variations depending on PV string capacity, irradiance, and PV module temperature, and this was used for learning and validation of deep learning. From the results of the study, it was confirmed that the PV fault diagnosis using I-V curves and deep learning is possible.

• Journal of Radiation Protection and Research
• /
• v.22 no.3
• /
• pp.143-151
• /
• 1997

As the pulse heights from a NaI(Tl) detector vary with the temperature of the measuring environment a significant change in temperature may affect the energy calibration of the spectrometer. The auto-adjustment of the channel corresponding to a pulse heights can be achieved by introducing an external reference source to compensate the temperature dependency of pulse heights, but unfavorable increases of the Compton continuum are caused due to the external source. In this study, the total absorption peaks dominant in the typical environmental gamma spectrum-239 keV from $^{212}Pb$, 351 keV from $^{214}Pb$, 1460 keV from $^{40}K$ and 2614 keV from $^{208}Tl$ for examples - were used as reference in the correction of energy calibration. With these peaks, the program to calibrate the energy of the s spectrum was developed using Microsoft Visual Basic language. The program developed here was applied to the environmental spectra measured at intervals of 30 minutes in the temperature range of from $-20^{\circ}C$ to $10^{\circ}C$ to demonstrate the validity and applicability. As a result of the test, the correction scheme appeared to be effective in the temperature changes encountered in the usual environment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.8
• /
• pp.823-829
• /
• 2004

In this paper, non-self-aligned SiGe HBTs with ${f}_\tau$ and${f}_max $above 50 GHz have been fabricated using an RPCVD(Reduced Pressure Chemical Vapor Deposition) system for wireless applications. In the proposed structure, in-situ boron doped selective epitaxial growth(BDSEG) and TiSi$_2$ were used for the base electrode to reduce base resistance and in-situ phosphorus doped polysilicon was used for the emitter electrode to reduce emitter resistance. SiGe base profiles and collector design methodology to increase ${f}_\tau$ and${f}_max $ are discussed in detail. Two SiGe HBTs with the collector-emitter breakdown voltages ${BV}_CEO$ of 3 V and 6 V were fabricated using SIC(selective ion-implanted collector) implantation. Fabricated SiGe HBTs have a current gain of 265 ∼ 285 and Early voltage of 102 ∼ 120 V, respectively. For the $1\times{8}_\mu{m}^2$ emitter, a SiGe HBT with ${BV}_CEO$= 6 V shows a cut-off frequency, ${f}_\tau$of 24.3 GHz and a maximum oscillation frequency, ${f}_max $of 47.6 GHz at $I_c$of 3.7 mA and$V_CE$ of 4 V. A SiGe HBT with ${BV}_CEO$ = 3 V shows ${f}_\tau$of 50.8 GHz and ${f}_max $ of 52.2 GHz at $I_c$ of 14.7 mA and $V_CE$ of 2 V.

• Nuclear Engineering and Technology
• /
• v.51 no.5
• /
• pp.1428-1435
• /
• 2019

The total ionizing dose (TID) and non ionizing energy loss (NIEL) effects of 100 MeV phosphorous ($P^{7+}$) and 80 MeV nitrogen ($N^{6+}$) ions on 200 GHz silicon-germanium heterojunction bipolar transistors (SiGe HBTs) were examined in the total dose range from 1 to 100 Mrad(Si). The in-situ I-V characteristics like Gummel characteristics, excess base current (${\Delta}I_B$), net oxide trapped charge ($N_{OX}$), current gain ($h_{FE}$), avalanche multiplication (M-1), neutral base recombination (NBR) and output characteristics ($I_C-V_{CE}$) were analysed before and after irradiation. The significant degradation in device parameters was observed after $100MeV\;P^{7+}$ and $80MeV\;N^{6+}$ ion irradiation. The $100MeV\;P^{7+}$ ions create more damage in the SiGe HBT structure and in turn degrade the electrical characteristics of SiGe HBTs more when compared to $80MeV\;N^{6+}$. The SiGe HBTs irradiated up to 100 Mrad of total dose were annealed from $50^{\circ}C$ to $400^{\circ}C$ in different steps for 30 min duration in order to study the recovery of electrical characteristics. The recovery factors (RFs) are employed to analyse the contribution of room temperature and isochronal annealing in total recovery.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.10
• /
• pp.883-888
• /
• 2007

Investigation of improving the properties of UV detector which uses the wide bandgap of ZnO are under active progress. The present study focused on the design and fabrication of i-ZnO/p-inversion $layer/n^--Si$ Epi. which is characterized with very thin p-type inversion layer for UV detectors. The i-ZnO thin film for achieving p-inversion layer which was grown by RF sputtering at $450^{\circ}C$ and then annealed at $400^{\circ}C$ in $O_2$ gas for 20 min shows good intrinsic properties. High (0002) peak intensity of the i-ZnO film is shown on XRD spectrum and it is confirmed by XPS analysis that the ratio of Zn : O of the i-ZnO film is nearly 1 : 1. Measurement shows high transmission of 79.5 % in UV range (< 400 nm) for the i-ZnO film. Measurement of $V_r-I_{ph}$ shows high UV photo-current of 1.2 mA under the reverse bias of 30 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.687-690
• /
• 2004

Fabrication and characterization of dye-sensitized TiO2 solar cells(DSSC) consisting of spray-coated TiO2 electrode, an electrolyte containing I-/I3- redox couple, and a Pt-coated counter electrode carried out, using mainly FE-SEM and solar simulator. Also, effect of rapid thermal annealing(RTA) temperatue on I-V curves of DSSCS consisting of approximately 10m thickness and $5{\times}5mm2$ active area. No significant difference in the apparent size of TiO2 clusters was observed with increasing RTA temperature. Also, an open circuit voltage(Voc) of approximately 0.70V and a short-circuit photocurrent(Jsc) of 8 to 12mA/cm2 were observed in the TiO2 solar cell. With increasing RTA temperature upto 550oC, photocurrent density of dye-sensitized solar cells was enhanced, leading to enhancing the efficiency of dye-sensitized solar cells having Pt-electroplated counter electrode.

• Proceedings of the KIEE Conference
• /
• 2006.07a
• /
• pp.81-82
• /
• 2006

본 논문에서는 765kV 변전소 건설시 최초로 도입된 시운전 시험을 중심으로 기술하였다. 시운전 시험은 765kV 초기 가압 및 상업 운전에 대비하여 사전에 문제점을 도출하고, 이에 대한 대책을 강구하기 위한 목적으로 시행되었다. 2004년에 시행한 신가평변전소에 대한 전력계통시험분야의 시운전시험을 중심으로 기술하였다. 기존의 345kV전력설비와 765kV전력설비(800kVGIS, 765kV7M.Tr)의 보호방식 차이에 따른 시험 방법, 시험 시 발생된 문제점 및 시험 결과에 대해 기술하였다.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.1
• /
• pp.100-104
• /
• 2011

In this work, an optimum condition of electrolytes preparation for photovoltaic cells application was investigated experimentally in terms of impedance and conversion efficiency of the cells. 3-methoxyppropionitrie and redox pairs with LiI and $I_2$ were used as stable solvents for fabrication of electrolyte. Efficiency comparison of the prepared cells carried out for various additives and ionic liquids. From the results, there was an optimum concentration (about 0.3 M) of ionic liquids for efficient cell fabrication. For case of electrolyte using single DMAp additive, the maximum conversion efficiency of the cell was 6.4%($V_{oc}$: 0.78V, $J_{sc}$: 14.4 mA/$cm^2$, ff: 0.57). For case of electrolyte using both DMAp and CEMim additives, the maximum conversion efficiency of the cell was 7.2%($V_{oc}$: 0.79V, $J_{sc}$: 16 mA/$cm^2$, ff: 0.57). From the result of electrochemical impedance measurement, both Z1 and Z3 values of binary additives-based cell decreased compared to those of single additive-based. This is due to the decreased in internal and charge transfer resistivities of the cells.