• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1429-1434
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• 2009

Recently electronic circuit pattern printing technologies like antennas of RFID process are paid attention. oven drying system is being used since drying and curing time of RFID Tag Gravure printing normally takes from 5 minutes and up to 30 minutes long. In this case the parental material which is of a sheet shape is possible, however, for a massive and a continuous production drying and curing process must be done on-line. This research compared and analyzed the an oven type drying device and a traditional hot-air drying device. Considering the experiment result, the cell depth that shows low resistivity, which doesn't consider the pattern difference, is $31{\sim}33{\mu}m$. Also, oven drying system showed some resistivity after around 120 seconds of drying time, and showed much better performance in minimum resistivity compared to the hot-air drying system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.803-807
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• 2008

A making process of DSC(dye sensitized solar cell) was presented. In general, Photo electrodes of DSC was made by using colloid paste of nano $TiO_2$ and processing of Doctor-blade printing and high temperature sintering for porous structure. These methods lead to cracks on $TiO_2$ surface and ununiform of $TiO_2$ thickness. This phenomenon is one factor that makes low efficiency to cells. After $TiO_2$ printing on TCO glass, a physical vibration was adapted for reducing ununiform of $TiO_2$ thickness. And a thermal treatment at low temperature(under $75^{\circ}C$) was adapted for reducing cracks on $TiO_2$ surface. In this paper, we have designed and manufactured an ultrasonic circuit (100W, frequency and duty variable) and a thermal equipment. Then, we have optimized forcing time, frequency and duty of ultrasonic irradiation and thermal heating for surface treatment of photo-electrode of DSC. In I-V characteristic test of DSC, ultrasonic and thermal treated DSC shows 19% improved its efficiency against monolithic DSC. And it shows stability of light-harvesting from drastically change of light irradiation test.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.262-263
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• 2011

Flexible electronics, a future technology of electronics, require a low cost integrated circuit that can be built on various types of the flexible substrates. As a potential candidate for this application, a single walled carbon nanotube network is studied as an active device with a scheme of thin film transistor. Transistors are formed on a plastic foil by the Roll-to-Roll (R2R) and the Roll-to-Device (R2D) printing method. For both printing methods, electrical transports for the transistors are presented with the temperature dependence of threshold voltage (V_Th) and mobility from the measured transfer curves at temperatures ranging from 10 K to 300 K. It is observed that ${\mu}=0.044cm^2/V{\cdot}sec$ and V_Th=7.28V for R2R and ${\mu}=0.025cm^2/V{\cdot}sec$ and V_Th=3.10V for R2D, both for the temperature at 300K. Temperature dependence of mobility and V_Th is observed. However for R2R, the temperature dependence of V_Th is constant. It is the difference between, R2R and R2D.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.347.1-347.1
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• 2016

Screen printing is commonly used to form the electrode for crystalline silicon solar cells. However, it has caused high resistance and low aspect ratio, resulting in decrease of conversion efficiency. Accordingly, Ni/Cu/Ag plating method could be applied for crystalline silicon solar cells to reduce contact resistance. For Ni/Cu/Ag plating, laser ablation process is required to remove anti-reflection layers prior to the plating process, but laser ablation results in surface damage and then decrease of open-circuit voltage and cell efficiency. Another issue with plating process is ghost plating. Ghost plating occurred in the non-metallized region, resulting from pin-hole in anti-reflection layer. In this paper, we investigated the effect of Ni/Cu/Ag plating on the electrical properties, compared to screen printing method. In addition, phosphoric acid layer was spin-coated prior to laser ablation to minimize emitter damage by the laser. Phosphorous elements in phosphoric acid generated selective emitter throughout emitter layer during laser process. Then, KOH treatment was applied to remove surface damage by laser. At this step, amorphous silicon formed by laser ablation was recrystallized during firing process and remaining of amorphous silicon was removed by KOH treatment. As a result, electrical properties as Jsc, FF and efficiency were improved, but Voc was lower than screen printed solar cells because Voc was decreased due to surface damage by laser process. Accordingly, we expect that efficiency of solar cells could be improved by optimization of the process to remove surface damage.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.7
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• pp.613-619
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• 2015

In this paper, we proposed a paper-based pattern-switchable antenna using inkjet-printing technology. The proposed antenna is composed of two bow-tie antennas and a switching network. The bow-tie antennas are inkjet-printed on paper using a low cost home printer. The switching network is built on a printed-circuit-board(PCB) and consists of a single-pole-double-throw(SPDT) switch and balun element. A double-sided parallel-strip line(DSPSL) can convert the unbalanced microstrip mode to the balanced strip mode. Two bow-tie antennas have different radiation patterns because of the different orientation of the reflectors. It is demonstrated from EM simulation and measurement that the radiation patterns of the proposed antenna are successfully switched by the SPDT.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.412-418
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• 2002

In this paper, the authors present the simulation results and the experimental considerations on the effects of the effects of the VCO oscillation characteristics caused by varying the length of the MSL and the composition capacitance of LC resonation circuity. Simulation was accomplished by nonlinear RF circuit simulator for designing and analyzing the RF characteristis of VCO. The samples with 3 different MSL lengths of which the length is 140mil, 280mil and 560mil respectively were fabricated by screen printing process. The oscillation frequency of each sample(VCO) was tuned to UHF band (750MHz~900MHz) by varying the capacitance of LC resonator circuit. The experimental results showed that the values of phase noise were -82, -93, -97[dBc/Hz] at 50[kHz] offset frequency, the pushing figures were 114, 94, 318[kHz] at applied voltage of $3\pm0.15$[V] and the harmonics were -21, -16, -13[dBc] for MSL lengths of 140mil 280mil, 560mil respectively. The frequency and output variation width were 779~898[MHz], -36~-33[dBm] for MSL with 140mil length; 818~836[MHz], -27.19~27.06[dBm] for 280mil; 751.54~751.198[MHz], -33.44~-33.31[dBm] for 560mil.

• Journal of IKEEE
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• v.22 no.4
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• pp.965-969
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• 2018

In the dye-sensitized solar cell, the semiconductor oxide plays an important role in the generation and transport of electrons, and thus extensive research on this has been continuously carried out. In this study, the characteristics of dye-sensitized solar cell are studied by fabricating semiconductor oxide doped with $V_2O_5$. The $TiO_2$ paste with $V_2O_5$ is prepared by the screen printing method of the sol - gel process and the surface and electrical properties are measured. The addition of $V_2O_5$ increased grain size and improved the open circuit voltage, short circuit current, charge factor and conversion efficiency of the dye sensitized solar cell.

• Current Photovoltaic Research
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• v.9 no.4
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• pp.123-127
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• 2021

This study was on electrode design for the realization of a solar cell that combines electrode formation and module integration process to overcome printing limitations. We used the passivated emitter rear contact (PERC) solar cell. Wafer size was 156.75 mm ×156.75 mm. The fabricated cell results showed that the open-circuit voltage of 649 mV, short-circuit current density of 36.15 mA/cm², fill factor of 68.5%, and efficiency of 16.06% with electrode conditions the 24BBs with the width 190 ㎛ and 90FBs with the width 45 ㎛. For improving efficiency, the characteristics of the solar cell were checked according to the change in the number of BBs and FBs and the change in line fine width. It is confirmed that the efficiency of the solar cell will be improved by increasing the number of FBs from 90 to 120, and increasing the line width of the FBs by about 10 ㎛ compared to the manufacturing solar cells.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.3
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• pp.43-49
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• 2010

Direct printing technology is an attractive metallization method, which has become immerging as "Green technology" to the conventional photolithography, on account of low cost, simple process and environment-friendliness. In order to commercialize the printed electronics in industry, it is essential to evaluate the electrical properties of conductive circuits using direct printing technology. In this contribution, we focused on the electrical characteristics of inkjet-printed circuits. A Cu nanoink was inkjet-printed onto a Bisaleimide triazine(BT) substrate with parallel transmission line(PTL) and coplanar waveguide(CPW) type, then was sintered at $250^{\circ}C$ for 30 min. We calculated the resistivity of printed circuits through direct current resistance by the measurement of I-V curve: the resistivity was approximately 0.558 ${\mu}{\Omega}{\cdot}cm$ which is about 3.3 times that of bulk Cu. Cascade's probe system in the frequency range from 0 to 30 GHz were employed to measure the Scattering parameter(S-parameter) with or without a gap between the substrate and the probe station chuck. The result of measured S-parameter showed that all printed circuits had over 5 dB of return loss in the entire frequency range. In the curve of insertion loss, $S_{21}$, showed that the PTL type circuits had better transmission of radio frequency (RF) than CPW type.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.1-10
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• 2020

This paper reviews the recent development of electronic textile technology, mainly focusing on chip-textile bonding. Before the chip-textile bonding, a circuit on the textile should be prepared to supply the electrical power and signal to the chip mounted on the fabrics. Either embroidery with conductive yarn or screen-printing with the conductive paste can be applied to implement the circuit on the fabrics depending on the circuit density and resolution. Next, chip-textile bonding can be performed. There are two choices for chip-textile bonding: fixed connection methods such as soldering, ACF/NCA, embroidery, crimping, and secondly removable connection methods like a hook, magnet, zipper. Following the chip-textile bonding process, the chip on the textile is generally encapsulated using PDMS to ensure reliability like water-proof.