• Proceedings of the Korean Society of Laser Processing Conference
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• 1999.05a
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• pp.39-42
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• 1999

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.129.1-129
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• 2003

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.05a
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• pp.15.1-15.1
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• 2008

• 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.

• Journal of Biomedical Engineering Research
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• v.39 no.1
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• pp.22-29
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• 2018

Intervertebral disc(IVD) mainly consists of Annulus fibrosus(AF) and Nucleus pulposus(NP), playing a role of distributing a mechanical load on vertebral body. IVD tissue engineering has been developed the methods to achieve anatomic morphology and restoration of biological function. The goal of present study is to identify the possibilities for creating a substitute of IVD the morphology and biological functions are the same as undamaged complete IVD. To fabricate the AF and NP combine biphasic IVD tissue, AF tissue scaffolds have been printed by 3D bio-printing system with natural biomaterials and NP tissues have been prepared by scaffold-free culture system. We evaluated whether the combined structure of 3D printed AF scaffold and scaffold-free NP tissue construct could support the architecture and cell functions as IVD tissue. 3D printed AF scaffolds were printed with 60 degree angle stripe patterned lamella structure(the inner-diameter is 5mm, outer-diameter is 10 mm and height is 3 mm). In the cytotoxicity test, the 3D printed AF scaffold showed good cell compatibility. The results of histological and immunohistochemical staining also showed the newly synthesized collagens and glycosaminoglycans, which are specific makers of AF tissue. And scaffold-free NP tissue actively synthesized glycosaminoglycans and type 2 collagen, which are the major components of NP tissue. When we combined two engineered tissues to realize the IVD, combined biphasic tissues showed a good integration between the two tissues. In conclusion, this study describes the fabrication of Engineered biphasic IVD tissue by using enable techniques of tissue engineering. This fabricated biphasic tissue would be used as a model system for the study of the native IVD tissue. In the future, it may have the potential to replace the damaged IVD in the future.

• ETRI Journal
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• v.40 no.3
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• pp.389-395
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• 2018

A novel class of planar metamaterial unit-cells consisting of a peace logo pattern is presented. A significant advantage of the proposed peace-logo planar metamaterial (PLPM) unit-cell over existing designs is its tunability, simplicity, and compatibility with microstrip structures. The theoretical analysis is founded on the famous transmission-line theory for the metamaterial concept. Then, the tunable dual-band two-sided PLPM (TSPLPM) unit-cell is designed by printing a similar PLPM pattern at the bottom of the substrate. The influence of the bottom PLPM pattern on the resonance frequencies of the unit-cell was analyzed by performing numerical simulations using CST Microwave Studio 2017 and HFSSv15 simulators. The results of the numerical simulations demonstrated that the proposed TSPLPM has the ability to control the resonance frequencies over 50 GHz-75 GHz for millimeter-wave applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.3
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• pp.236-240
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• 2012

Limiting thermal exposure time using rapid thermal processing(RTP) has emerged as promising simplified process for manufacturing of solar cell in a continuous way. This paper reports the simplification of co-firing using RTP. Actual temperature profile for co-firing after screen printing is a key issue for high-quality metal-semiconductor contact. The plateau time during the firing process were varied at $450^{\circ}C$ for 10~16 sec. Glass frit in Ag paste etch anti-reflection layer with plateau time. Glass frit in Ag paste is important for the Ag/Si contact formation and performances of crystalline Si solar cell. We achieved 17.14% efficiency with optimum conditions.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.567-572
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• 2013

In many electro-devices, the vacuum process is used as the manufacturing process. However, the vacuum process has a problem, it is difficult to apply to a continuous process such as a R2R(roll to roll) printing process. In this paper, we propose an ESD (electro static deposition) printing process has been used to apply an organic solar cell of thin film forming. ESD is a method of liquid atomization by electrical forces, an electrostatic atomizer sprays micro-drops from the solution injected into the capillary with electrostatic force generated by electric potential of about several tens kV. The organic solar cell based on a P3HT/PCBM active layer and a PEDOT:PSS electron blocking layer prepared from ESD method shows solar-to-electrical conversion efficiency of 1.42% at AM 1.5G 1sun light illumination, while 1.86% efficiency is observed when the ESD deposition of P3HT/PCBM is performed on a spin-coated PEDOT:PSS layer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.19-24
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• 2017

In this paper, we propose a textile metamaterial absorber that using screen printing technology. A unit cell of the proposed absorber is motivated from the commercial Chanel logo for wearable applications. The complex impedance of the designed unit cell is analyzed by full-wave simulation. To verify its performance, the proposed metamaterial absorber is fabricated where the silver conductive ink is screen printed on an ordinary textile. From experimental results, the absorptivity of the proposed absorber is around 93 % at 10.8 GHz under normal incidence.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1533-1536
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• 2006

A novel single cell gap transflective liquid crystal display was developed. By using the ink jet printing technology, we fabricated a transflective liquid crystal display with the hybrid alignment in the reflective region and the homogeneous alignment in the transmission region. Compared with the traditional technologies, our technology provided the advantages of easy process, high yield, fast throughput, and less material usage. We also applied this technology to the 2.4 inch prototype. This panel could be implemented in the handheld product applications.