• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.6
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• pp.505-508
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• 2017

This paper analyzes the effect of metal dummy structures in CMOS on antenna performances of a sub-terahertz on-chip microstrip patch antenna. A 400-GHz on-chip antenna is designed in a 45-nm CMOS process, and the resonance frequency and efficiency of the antenna are analyzed depending on the density of metal dummy structures. Antennas integrated with an oscillator are designed and fabricated for verification, and measurements are performed using quasi-optical methods with an FTIR and bolometer. The measurement results shows that the radiated power drops from 420 nW to 90 nW by 6.8 dB due to the dummy structures with the density of 27 %.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.865-868
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• 2011

An organic substance, hydroquinone is used to form clathrate compounds in order to identify separation characteristics of carbon dioxide in flue gas. Formed samples were analyzed by means of the solid-state $^{13}C$ nuclear magnetic resonance (NMR) and Raman spectroscopic methods to examine enclthration behaviors of guest species. In addition, elemnetal analysis was also performed in order to evaluate separation efficiency of $CO_2$ in a quantitative way. Based on the experimental results obtained, $CO_2$ molecules are found to be captured into the clathrate compound more readily than $N_2$ molecules. Moreover, because such preferential enclathration is even more significant at low pressure conditions, $CO_2$ separation/recovery from flue gas can be achieved with minimizing additional energy cost for the technique. Experimental results obtained in this study can provide useful information on separation techniques of flue gas or selective separation of gas mixtures in the future.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1165-1169
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• 2012

The fluorescence intensity of DNA-intercalated ethidium with [ethidium]/[DNA base] being 0.005 was quenched upon the binding of another intercalating ligand, meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP). Addition of $Ca^{2+}$ enhanced the quenching efficiency. The range of separations between donor and acceptor molecules, within which total quenching occurs, was calculated using a one-dimensional resonance energy transfer mechanism to be 9.5 base-pairs or $32.3{\AA}$ in the absence of $Ca^{2+}$ ions. The distance increased to 18.7 base-pairs or about $63.6{\AA}$ in the presence $100{\mu}M$ $Ca^{2+}$. Considering that (1) $Ca^{2+}$ had little effect on the binding modes of ethidium and TMPyP, which was investigated by reduced linear dichroism and (2) spectral overlap between the emission spectrum of ethidium and the absorption spectrum of TMPyP was maintained in the presence of $Ca^{2+}$, contributions from orientation factor and spectral overlap to $Ca^{2+}$-induced enhancement in DNA mediated energy transfer was limited. Although there is no direct evidence, electron transfer along the DNA stem may accompany the observed fluorescence quenching. In this respect, DNA bound $Ca^{2+}$ act as a partially conducting medium.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1414-1420
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• 2013

Five novel spiro[benzo[c]fluorene-7,9'-fluorene] based dyes, including 5-[spiro[benzo[c]fluorene-7,9'-fluoren]-5-yl] spiro[benzo[c]fluorene-7,9'-fluorene] (7), 5-[spiro[benzo[c]fluorene-7,9'-fluoren]-9-yl] spiro[benzo[c]fluorene-7,9'-fluorene] (8), 5-[spiro[benzo[c]fluorene-7,9'-fluoren]-2'-yl] spiro[benzo[c]fluorene-7,9'-fluorene] (9), 9-[spiro[benzo[c]fluorene-7,9'-fluoren]-9-yl] spiro[benzo[c]fluorene-7,9'-fluorene] (10), and 2'-[spiro[benzo[c]-fluorene-7,9'-fluoren]-2'-yl] spiro[benzo[c]fluorene-7,9'-fluorene] (11) were successfully prepared from the corresponding halogen and boronic acid derivatives through the Suzuki coupling reaction, respectively. Chemical structures were confirmed by $^1H$ nuclear magnetic resonance (NMR), $^{13}C$ NMR, Fourier transforminfrared spectrscopy, mass spectroscopy, and elemental analysis. The thermal properties were determined by differential scanning calorimetry and thermal gravimetric analysis. The relationships between the optical and electrochemical properties and the combined positions between these dimers were systematically investigated using UV-vis, photoluminescence (PL), and photoelectron spectroscopy. These five dimers exhibited high fluorescent quantum yields and good morphological stability with high glass transition states > $174^{\circ}C$. Dimer 7 showed a UV absorbance peak at 353 nm, emission PL peak at 424 nm, and quantum efficiency of 0.62 in a cyclohexane solution.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1065-1073
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• 1999

This paper analyzed the ground bounce caused by the power plane resonance in the multilayered printed circuit board(PCB) using the Haar-wavelet-based Multiresolution Time-Domain (MRTD). In conventional Finite-Difference Time-Domain(FDTD), the highly fine vertical cell is needed to represent the distance between $V_{cc}$ plane and ground plane since the two planes are very close. Therefore the time step $\Deltat$ must be very small to satisfy the stability condition. As a result, a large number of iterations are needed to obtain the response in wanted time. For this problem, this paper showed that the computation time can be reduced by application of the MRTD method. The results obtained by the MRTD agree very well with those by FDTD method and analytic solutions. In conclusion, this paper proved the efficiency and accuracy of MRTD method for analyzing the EMI/EMC problems in PCB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.12
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• pp.1399-1405
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• 2012

Transmission cross section characteristics as a measure of transmission efficiency has been analyzed numerically for the H-shaped and C-shaped small apertures in the infinite conducting plane when illuminated by a plane wave. It has been found that C-shaped aperture has the larger transmission cross section than that of H-shaped aperture under the condition of the same perforated aperture area. Main attention has been focused on studying the mutual coupling effect between two C-shaped apertures on the transmission cross section characteristic. Parallel configuration which is composed of two C-shaped apertures arranged along the x-axis and collinear configuration which is composed of two C-shaped arrayed along the y-axis have been investigated from the viewpoint of enhanced transmission cross section characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.194-200
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• 2020

Perylene bisimide derivatives are developed for red organic phosphor because of their advantages, such as excellent luminous efficiency and high thermal stability. Despite these advantages, they have poor solubility characteristics in organic solvents and short emission wavelength as red organic phosphor for hybrid light-emitting diodes (LEDs). In this study, we prepared terrylene bisimide using a coupling reaction and swallow-tail imide group, which has excellent solubility. The structures and properties of swallow-tail terrylene bisimide (9C) were analyzed using ¹H-nuclear magnetic resonance (¹H-NMR), Fourier-transform infrared (FT-IR), UV/Vis spectroscopy, and thermal gravimetric analysis (TGA). The maximum absorption wavelength of (9C) in the UV/Vis spectrum was 647 nm, and the maximum emission wavelength was 676 nm. In the TGA, (9C) demonstrated good thermal stability with less than 5 wt% weight loss up to 415℃. In the solubility test, (9C) has a good solubility of more than 5 wt% in chloroform and dichloromethane. When the compounds (9C) were mixed with PMMA (polymethly methacrylate), the films showed peaks at 680 nm in the PL spectra. The results verify the suitability of (9C) as a red organic phosphor for hybrid LEDs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.6
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• pp.26-33
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• 2008

This paper presents a new full-bridge soft switching PWM DC-DC converter circuit topology that adding one switcher, one lossless snubber quasi-resonance capacity to power source for general welding machine This full-bridge soft switching DC-DC convoter· topology can applicable 600[V] switching device (IGBT)incase of AC 400[V] common power source because the voltage of active switcher is 1/2 of DC bus line voltage. And low voltage hight current out)ut that first coil current is smaller than second coil current in high frequency transformer can be obtained with decreasing path loss in conventional DC bus line switcher. As it operate ZCS/ZVS in full range, high frequency, high efficiency and high output are implemented at low voltage and high DC current switching power supplies. All of this items are got from simulation and the result of experiment. If make up for the weak points of this proposed circuit, it will be used more easily for next generation TIG, MIG and MAG type of arc-welding machine.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.281.2-281.2
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• 2013

Since heavy metal ions included in water or food resources have critical effects on human health, highly sensitive, rapid and selective analysis for heavy metal detection has been extensively explored by means of electrochemical, optical and colorimetric methods. For example, quantum dots (QDs), such as semiconductor QDs, have received enormous attention due to extraordinary optical properties including high fluorescence intensity and its narrow emission peaks, and have been utilized for heavy metal ion detection. However, the semiconductor QDs have a drawback of serious toxicity derived from cadmium, lead and other lethal elements, thereby limiting its application in the environmental screening system. On the other hand, Graphene oxide (GO) has proven its superlative properties of biocompatibility, unique photoluminescence (PL), good quenching efficiency and facile surface modification. Recently, the size of GO was controlled to a few nanometers, enhancing its optical properties to be applied for biological or chemical sensors. Interestingly, the presence of various oxygenous functional groups of GO contributes to opening the band gap of graphene, resulting in a unique PL emission pattern, and the control of the sp2 domain in the sp3 matrix of GO can tune the PL intensity as well as the PL emission wavelength. Herein, we reported a photoluminescent GO array on which heavy metal ion-specific DNA aptamers were immobilized, and sensitive and multiplex heavy metal ion detection was performed utilizing fluorescence resonance energy transfer (FRET) between the photoluminescent monolayered GO and the captured metal ion.

• Journal of Advanced Navigation Technology
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• v.17 no.3
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• pp.332-345
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• 2013

In this paper, recently, it is described to the piezoelectric transformer technology develops, because it was have to favorable characteristics such as electromagnetic-noise free, compact size, higher efficiency, and superior power density, flux linkage, noiseless, etc. its resonance frequency was used to output waveform of a sine wave. A rotor speed identification method of induction motor based on the theory of flux model reference adaptive system(FMRAS). The estimator execute the rotor speed identification so that the vector control of the induction motor may be achieved. The improved auxiliary variable of the model are introduced to perform accurate rotor speed estimation. The control system is composed of the PI controller for speed control and the current controller using space voltage vector PWM techniuqe and DC-DC converter. High speed calculation and processing for vector control is carried out by digital signal one chip microprocessor. Validity of the proposed control method is verified through simulation and experimental results.