• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.3
• /
• pp.289-295
• /
• 2014

In this paper a wideband active balun using advanced phase correction architecture is proposed. The proposed active balun is constructed with each different architecture of active balun combined with the cascode architecture to improve phase correction performance compared with conventional phase correction techniques. Operating over 0.6~2.0 GHz band, the proposed balun shows $10^{\circ}$ of phase error and 2 dB of gain error with 7 mW power consumption from 1.8 V supply voltage.

• Electronics and Telecommunications Trends
• /
• v.35 no.4
• /
• pp.53-64
• /
• 2020

The terahertz (THz) region lies in between the millimeter and infrared spectral bands. A THz wave has the characteristics of non-invasiveness and non-ionization due to low photon energies, while having high penetrability in dielectrics. In addition, since the resonance frequencies of various molecules are included in the THz band, research on the application of spectral analysis and non-destructive testing has been widely studied. Towards this end, the research and development of THz detectors has become increasingly important in order to assess their applications in different areas such as astronomy, security, industrial non-destructive evaluations, biological applications, and wireless communications. In this report, we summarize the operating principles, characteristics, and utilization of various broadband technologies in THz detection devices. Further, we introduce the development status of our Schottky barrier diode technology as one of the broadband THz detectors that can be easily adopted as direct detectors in many fields of applications.

• Korean Journal of Microbiology
• /
• v.14 no.1
• /
• pp.39-47
• /
• 1976

This experiment was designed to study the effects of temperature on the peroxidase isoenzymes of a mesophilic microorganism, Escherichia coli (grown within biokinetic zone). Optimum temperature for the growth of E. coli was $37{\circ}C.$ Three different temperatures, 20, 30 and $40{\circ}C,$ were selected. And the isoenzyme patterns of peroxidase of E. coli, growth respectively at each temperature, were analysed by disc electrophoresis. The sample of 20.deg.C showed 4 bands, that of 30.deg.C, 5 bands and that of 40.deg.C, 6 bands. Two dark bands (higher molecular weight, 56,000 and 54,000) and two light bands (lower molecular weight, 11,500 and 10,000) were constant at all samples. But two intermediate bands (M.W.44,000 and 34,000) were variable ; at $20{\circ}C,$ no banding pattern, one band 9M.W. 34,000) only at $30{\circ}C,$ and at $40{\circ}C$ two bands were appeared. And the shifts of growth temperatures between 30.deg.C and 40.deg.C showed the alteration of the isoenzyme patterns ; the isoenzyme patterns of the smaple of tmeperature shift from $30{\circ}C$ to $40{\circ}C$ were same as that of 40.deg.C and vice versa.

• Journal of the Korean Physical Society
• /
• v.73 no.9
• /
• pp.1351-1355
• /
• 2018

The photocurrent characteristics of zinc-oxide (ZnO) thin-film transistors (TFTs) prepared using radio-frequency sputtering and spin-coating methods were investigated. Various characterization methods were used to compare the physical and the chemical properties of the sputtered and the spin-coated ZnO films. X-ray photoelectron spectroscopy was used to investigate the chemical composition and state of the ZnO films. The transmittance and the optical band gap were measured by using UV-vis spectrometry. The crystal structures of the prepared ZnO films were examined by using an X-ray diffractometer, and the surfaces of the films were investigated by using scanning electron microscopy. ZnO TFTs were prepared using both sputter and solution processes, both of which showed photocurrent characteristics when illuminated by light. The sputtered ZnO TFTs had a photoresponsivity of 3.08 mA/W under illumination with 405-nm light while the solution-processed ZnO TFTs had a photoresponsivity of 5.56 mA/W. This study provides useful information for the development of optoelectronics based on ZnO.

• Korean Journal of Optics and Photonics
• /
• v.5 no.1
• /
• pp.120-124
• /
• 1994

PBH-DFB-LD emitting at $1.55\mu\textrm{m}$ wavelength has been fabricated for 2.5 Gbps optical fiber communications. For fabrication of PBH-DFB-LD. inteference expose for grating formation and 3-step LPE epitaxial growth was used. Fabricated PBH-DFB-LD operates in single longitudinal mode with more than 35dB SMSR and its threshold current is less than 15 mA. The operating wavelength is 1530-1550 nm with the temperature dependence of $0.9\AA/^{\circ}C$. Coupling coefficient(K) was estimated as $$97 cm^{-1} by means of stop-band measurement. PBH-DFB-LD fabricated in this experiment can be applicable as light source for 2.5 Gbps optical fiber communication system. ystem.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.247.1-247.1
• /
• 2016

Low-cost, high efficiency solar cells are tremendous interests for the realization of a renewable and clean energy source. ZnTe based solar cells have a possibility of high efficiency with formation of an intermediated energy band structure by impurity doping. In this work, ZnO/ZnTe:Cr and ZnO/i-ZnTe structures were fabricated by pulsed laser deposition (PLD) technique. A pulsed (10 Hz) Nd:YAG laser operating at a wavelength of 266 nm was used to produce a plasma plume from an ablated a ZnTe target, whose density of laser energy was 10 J/cm2. The base pressure of the chamber was kept at approximately $4{\times}10-7Torr$. ZnTe:Cr and i-ZnTe thin films with thickness of 210 nm were grown on p-Si substrate, respectively, and then ZnO thin films with thickness of 150 nm were grown on ZnTe:Cr layer under oxygen partial pressure of 3 mTorr. Growth temperature of all the films was set to $250^{\circ}C$. For fabricating ZnO/i-ZnTe and ZnO/ZnTe:Cr solar cells, indium metal and Ti/Au grid patterns were deposited on back and front side of the solar cells by using thermal evaporator, respectively. From the fabricated ZnO/ZnTe:Cr and ZnO/i-ZnTe solar cell, dark currents were measured by using Keithley 2600. Solar cell parameters were obtained under Air Mass 1.5 Global solar simulator with an irradiation intensity of 100 mW/cm2, and then the photoelectric conversion efficiency values of ZnO/ZnTe:Cr and ZnO/i-ZnTe solar cells were measured at 1.5 % and 0.3 %, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.857-860
• /
• 2004

Cubic CdS thin film with the strongest XRD peak (111) at diffraction angle $(\theta)$ of 26.5 was well made at substrate temperature of $150^{\circ}C$. At that time, lattice constant a of the thin film was $5.79{\AA}$, grain size of that was more over ${\mu}m$ and it's resistivity was over $10^3{\Omega}cm$. And the peak of diffraction intensityat miller index (111) of CdS:In thin film with dopant In of 1 atom% was shown higher about 20 % than undoped CdS thin film. Also, CdS:In thin film had in part hexagonal structure among cubic structure as secondary phase. Lattice constant of a and grain size of secondary phase of the film with dopant In of 1 atom% was $5.81{\AA}$ and around $1{\mu}m$ respectively The lowest resistivity of $5.1{\times}10^{-3}{\Omega}cm$ was appeared on dopant In of 1.5 atom%. Optical band gap of undoped CdS thin film was 2.43 eV and CdS:In thin film with dopant In of 0.5 atom% had the largest band gap 2.49 eV.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.2
• /
• pp.115.2-115.2
• /
• 2011

UWISH2 (UKIRT Widefield Infrared Survey for $H_2$) is an unbiased, narrow-band imaging survey of the Galactic plane in the $H_2$ 1-0 S(1) emission line at $2.122{\mu}m$ using the Wide-Field Camera (WFCAM) at the United Kingdom Infrared Telescope (UKIRT). The survey covers about 150 square degrees of the first Galactic quadrant ($10^{\circ}$ < l < $65^{\circ}$; $-1.3^{\circ}$ < b < $+1.3^{\circ}$). The images have a $5{\sigma}$ detection limit of point sources of K~18 mag and the surface brightness limit is $10^{-19}\;W\;m^{-2}$ $arcsec^{-2}$. The survey operation began on 28 July 2009 and has completed on 17 August 2011. We have been studying the supernova remnants (SNRs) in the UWISH2 survey area. Among the known 274 Galactic SNRs, the survey area includes 65 SNRs or 24 percent of the known SNRs. The wide-field and high-quality UWISH2 images allow us to identify both the diffuse extended and compact $H_2$ emission associated with SNRs, which is useful for understanding their physical environment and evolution. The continuum is subtracted from the narrow-band $H_2$ images using the K-band continuum images obtained as part of the UKIDSS GPS (UKIRT Infrared Deep Sky Survey of the Galactic Plane). So far, we have inspected 42 SNRs, and found distinct H2 emission in 14 SNRs. The detection rate is 33%. Some of the SNRs show bright, complex, and interesting structures that have never been reported in previous studies. In this report, we present our identification scheme and preliminary results.

• Advances in nano research
• /
• v.14 no.1
• /
• pp.1-15
• /
• 2023

Driven by the scaling down of transistor node technology, graphene became of interest to many researchers following the success of its fabrication as graphene nanoribbons (GNRs). However, during the fabrication of GNRs, it is not uncommon to have defects within the GNR structures. Scaling down node technology also changes the modelling approach from the classical Boltzmann transport equation to the quantum transport theory because the quantum confinement effects become significant at sub-10 nanometer dimensions. The aim of this study is to examine the effect of Stone-Wales defects on the electronic properties of GNRs using a tight-binding model, based on Non-Equilibrium Green's Function (NEGF) via numeric computation methods using MATLAB. Armchair and zigzag edge defects are also implemented in the GNR structures to mimic the practical fabrication process. Electronic properties of pristine and defected GNRs of various lengths and widths were computed, including their band structure and density of states (DOS). The results show that Stone-Wales defects cause fluctuation in the band structure and increase the bandgap values for both armchair GNRs (AGNRs) and zigzag GNRs (ZGNRs) at every simulated width. In addition, Stone-Wales defects reduce the numerical computation DOS for both AGNRs and ZGNRs. However, when the lengths of the structures increase with fixed widths, the effect of the Stone-Wales defects become less significant.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.3
• /
• pp.273-279
• /
• 1993

Hydrolytic patterns of 11S globulin (glycinin), storage protein of soybean, by soymilk-clotting enzymes Iand IIfrom Bacillus sp. K-295G-7, which was the first soymilk-clotting enzyme to be found in a bacteria, was investigated. The clotting time of about 4~5 min is revealed by the Enzymes Iand II(0.025 units at 35$^{\circ}C$) on the acidic subunit. In electrophoresis, acidic subunit (A$_3$, M.W. 45,000) disappeared almost completely within 2 min and new products corresponding to the molecular weight of 16,000 and 20,000 were formed by the action of Enzymes I and II. Furthermore, Enzyme II produced a degradation compound having a molecular weight of about 30,000. In contrast, the hydrolytic patterns of basic subunit (M.W. 20,000) by Enzymes I and II were similar, but Enzyme II produced low molecular weight products slower than that of Enzyme I.