• Journal of electromagnetic engineering and science
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• v.11 no.3
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• pp.143-151
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• 2011

This paper presents a survey of recent wireless power transfer systems. The issue of wireless power transfer is to achieve a highly efficient system with small positioning errors of the facilities setting. Several theories have been presented to obtain precise system design. This paper presents a summary of design theory for short range power transfer systems and detailed formulations based on a circuit model and an array of infinitesimal dipoles. In addition to these theories, this paper introduces a coil array scheme for improving the efficiency for off axis coils. In the microwave range, tightly coupled resonators provide a highly efficient power transfer system. This paper present san-overlay resonator array consisting of half wavelength microstrip line resonators on the substrate with electromagnetically coupled parasitic elements placed above the bottom resonators. The tight couplings between the waveguide and the load resonator give strong power transmission and achieve a highly efficient system, and enables a contact-less power transfer railroad. Its basic theory and a demonstration of a toy vehicle operating with this system are presented. In the last topic of this paper, harmonic suppression from the rectenna is discussed with respect to acircular microstrip antenna with slits and stubs.

• Journal of Welding and Joining
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• v.27 no.3
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• pp.67-72
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• 2009

The flux cored arc welding (FCAW) process is one of the most frequently employed and important welding process due to high productivity and excellent workability. The process is performed either as an automated process or as a semi-automatic process. In FCAW process, welding voltage has been considered as a qualitative indication of arc length. But it is necessary to let welding operators know, maintain and manage the arc length directly by estimating and displaying it. In this study, to develop arc length estimation technique, we measured a welding circuit resistance($R_sc$) and then we calculated welding circuit voltage drop($V_sc$). Also, we measured arc peak voltage($V_ap$). By subtracting $V_sc$ from $V_arc$, we can easily calculate net arc voltage drop($V_arc$). Consequently, we suggested arc length estimating equation and basic algorithm by regressive analyzing the relationship between net arc voltage drop($V_arc$) and real arc length(Larc) measured by high speed camera. Therefore, arc length can be predicted by just monitoring welding current and voltage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.428-435
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• 1998

SOI-like-bulk CMOS device is proposed, which having the advantages of SOI(Silicon On Insulator) and protects short channel effects efficiently with adding partial epitaxial process at standard CMOS process. SOI-like-bulk NMOS and PMOS with 0.25${\mu}{\textrm}{m}$ gate length have designed and optimized through analyzing the characteristics of these devices and applying again to the design of processes. The threshold voltages of the designed NMOS and PMOS are 0.3[V], -0.35[V] respectively and those have shown the stable characteristics under 1.5[V] gate and drain voltages. The leakage current of typical bulk-CMOS increase with shortening the channel length, but the proposed structures on this a study reduce the leakage current and improve the subthreshold characteristics at the same time. In addition, subthreshold swing value, S is 70.91[mV/decade] in SOI-like-bulk NMOS and 63.37[mV/ decade] SOI-like-bulk PMOS. And the characteristics of SOI-like-bulk CMOS are better than those of standard bulk CMOS. To validate the circuit application, CMOS inverter circuit has designed and transient & DC transfer characteristics are analyzed with mixed mode simulation.

• Journal of Electrochemical Science and Technology
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• v.15 no.3
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• pp.421-426
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• 2024

Ru dye (Z-907) is a crucial photosensitizing material in dye-sensitized solar cells (DSSCs). To enhance the utilization of Ru dye's photosensitizing properties in bulk heterojunction solar cells, a method was developed to synthesize phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles that are chemically linked to Ru dye. PCBM contains a methoxy (-OCH₃) group, whereas Ru dye incorporates a carboxyl group (-COOH) within its molecular structure. By exploiting these complementary functional groups, a successful bond between Ru dye and PCBM was established through an anhydride functional group. The coupling of PCBM with Ru dye results in a modification of the energy levels, yielding lower LUMO (3.8 eV) and HOMO (6.1 eV) levels, compared with the LUMO (3.0 eV) and HOMO (5.2 eV) levels of Ru dye alone. This configuration potentially facilitates efficient electron transfer from Ru dye to PCBM, alongside promoting hole transfer from Ru dye to the conducting polymer. Consequently, the bulk heterojunction solar cells incorporating this Ru dye-PCBM configuration demonstrate superior performance, with an open circuit voltage (V_oc) of 0.62 V, short circuit current (J_sc) of 0.63 mA cm^-2, fill factor (FF) of 65.6%, and a photovoltaic conversion efficiency (η) of 0.25%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.5
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• pp.1035-1041
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• 2017

In magnetic resonance-based wireless power transfer (WPT) systems, frequency splitting phenomenon, in which power transfer efficiency (PTE) decreases seriously as resonators are close to each other, is the problem that we should address for reliable power transfer in short distance. In this paper, we present WPT systems using an equivalent circuit model and analyze PTE and marginal coupling coefficient ($k_{split}$) where the frequency splitting occurs. In addition, we perform circuit-level simulations using Advanced Design System, and show that the achievable PTE is different for the structures of resonators when k>$k_{split}$. We confirm that higher PTE can be ensured as k increases in the case of identical resonators, while PTE is degraded as k increases in the case of non-identical resonators. Therefore, in short distance, in which k>$k_{split}$, it is more efficient for achieving reliable PTE to use identical resonators rather than non-identical resonators.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.2
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• pp.128-137
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• 1999

Recently the pelionnance of CO2 arc welding machine has been advanced significantly through the adoption of i invelter circuit topology. which made it possible to improve welding perfonnances such as spatter generation and bead s state. But the conventional inverter arc welding machine generates constant output voltage which cause much spatter g generation dUling short-circuit and arc start time because it is unable to control output current instantaneously. So this p paper representes wavefCnm controlled inverter arc welding machine which control the wavefonn of welding current and t thus to suppress the spatter generation. And the system designed in this paper is the digital controller using single chip m microprocessor of 80C196KC. As a result of perfonnance test for this system, the spatter generation is reduced and s shOlt-circuit time period is stabilized compared to conventional one. And more by using switched mode rectifier for A AC/DC power convelter. unity power factor is maintained and low order halmonic spectrum is supressed.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.60.1-60.1
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• 2010

Chemically functionalized plant oils such as acrylated epoxidized soybean oil (AESO) and maleinized acrylated epoxidized soybean oil (MAESO) were used as new bio-based binders for $TiO_2$ electrodes of dye-sensitized solar cells (DSSC). More porous networks and larger porosities were fabricated on the $TiO_2$ films using plant oil binders due to the larger number of functionalities, in comparison with the film using polyethylene glycol (PEG). The charge-transfer resistance in the $TiO_2$ films was considerably shrunk due to the reduced impurity states. The short circuit photocurrent (Isc) and the open circuit photovoltage (Voc) of the cell using plant oil binders increased and the conversion efficiency improved significantly.

• Journal of Welding and Joining
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• v.9 no.3
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• pp.34-40
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• 1991

An automatic welding system was constructed with a personal computer to capture the welding data in addition to vision seam tracking for the gas metal arc welding process. The monitoring of welding signals is composed of the acquisition of welding voltage and current, obtained by using two differential amplifiers and A/D converters, and processing of the measured data. Using interrupt handing circuit for time sharing, two jobs of seam tracking and monitoring were performed at the required sampling time. Relations between welding signals and various welding circumstances were analyzed from the experimental results.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.441-441
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• 2014

The characteristics of hybrid conductive films based on multilayer graphene and silver grid have been investigated for the high-performance and flexible organic solar cells. The hybrid conductive films have been prepared on glass and polyethylene terephthalate (PET) substrates using conventional photolithography process and transfer process of graphene. The optical and electrical properties of prepared conductive films show transmittance of 87% at 550nm and sheet resistance of $28{\Omega}/square$. The electromechanical properties were also investigated in detail to confirm the flexibility of the hybrid films. OSCs have been fabricated on the hybrid conductive films based on graphene and silver grid on glass substrate. The power conversion efficiency of 2.38%, a fill factor of 51%, an open circuit voltage of 0.58V and a short circuit current of $8.05mA/cm^2$ were obtained from the device on glass substrate. The PCE was enhanced 11% compared with OSCs on the MLG films without silver grid.

• Journal of the Optical Society of Korea
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• v.12 no.3
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• pp.162-165
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• 2008

A novel planar lightwave circuit(PLC) triplexer using a three-waveguide interferometer(TWI) is proposed and examined using the transfer matrix and the beam propagation methods. The proposed triplexer consists of two three-waveguide couplers and three waveguides connecting the couplers. Simulation for the TWI triplexer shows the excess losses of 0.03 dB and 0.94 dB with the crosstalks of -22.3 dB and -14.5 dB in reception, respectively, for the wavelength of 1490- and 1550-nm, while showing the excess loss of 1.75 dB in transmission for the wavelength of 1310 nm. The proposed design shows compact feature as short as 11.5 mm for the refractive-index contrast of 0.45%.