전기저항 분석을 통한 은나노 입자 합성 시의 입자거동 연구

윤영우,유시홍,양성주,이성의,Yoon, Young Woo,Ryu, Si Hong,Yang, Sung Joo,Lee, Seong Eui 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.8

This study examined the size and shape of the nano-silver particle through the analysis of electrical resistance when synthesizing nano-sized silver by using the chemical liquid reduction. Changes in particle behaviors formed according to the changes in electronic characteristics by electric resistance in each time period in the beginning of reduction reaction in a course of synthesizing the nano-silver particle formation were studied. In addition, analysis was conducted on particle behaviors according to the changes in concentration of $AgNO_3$ and in temperature at the time of reduction and nucleation and growth course when synthesizing the particles based on the particle behaviors were also examined. As the concentration of $AgNO_3$ increased, the same amount of resistance of approximately $5{\Omega}$ was increased in terms of initial electronic resistance. Furthermore, according to the result of formation of nuclear growth graph and estimation of slope based on estimated resistance, slops of $6.25{\times}10^{-3}$, $2.89{\times}10^{-3}$, and $1.85{\times}10^{-3}$ were derived from the concentrations of 0.01 M, 0.05 M, and 0.1 M, respectively. As the concentration of $AgNO_3$ increased, the more it was dominantly influenced by the nuclear growth areas in the initial phase of reduction leading to increase the size and cohesion of particles. At the time of reduction of nano-silver particle, the increases of initial resistance were $4{\Omega}$, $4.2{\Omega}$, $5{\Omega}$, and $5.3{\Omega}$, respectively as the temperature increased. As the temperature was increased into $23^{\circ}C$, $40^{\circ}C$, $60^{\circ}C$, and $80^{\circ}C$, slopes were formed as $4.54{\times}10^{-3}$, $4.65{\times}10^{-3}$, $5.13{\times}10^{-3}$, and $5.42{\times}10^{-3}$ respectively. As the temperature increased, the particles became minute due to the increase of nuclear growth area in the particle in initial period of reduction.

Micro LED 제작을 위한 Color Filter용 잉크젯 공정 적색, 녹색 형광체 잉크 연구

김보중,유시홍,양효실,문영부,윤창번 한국전기전자재료학회 2023 전기전자재료학회논문지 Vol.36 No.5

In this paper, in order to apply the CF (color filter) type of the micro light emitting device (Micro LED) display method, a study on the manufacturing process of red and green phosphor inks for the inkjet process was conducted. The blue light-emitting KSF and LuAG phosphors were respectively used to control the phosphor particle size to about 1μm, and a phosphor ink was prepared by synthesizing with a low-viscosity solution (IPA/Eg). A chemical dispersion method was applied to selectively control the dispersion characteristics in the manufacture of phosphor inks, and in particular, phosphor inks with a dispersant applied a dispersant secured stable dispersion characteristic compared to phosphor inks without a dispersion process. Therefore, it seems possible to manufacture CF for Micro LED through an inkjet process capable of controlling the dispersion characteristics of phosphor ink.

MoO3 보호막 적층 Si3N4기반 세라믹 히터 소자 연구

전용민,유시홍,김선호,이성의 대한금속·재료학회 2022 대한금속·재료학회지 Vol.60 No.4

Currently, the need for high performance heaters for industrial application is increasing, and repeated wear, rapid temperature change, and uneven temperature can cause deteriorating quality and reduced productivity. The ceramic heater in this study consists of a substrate, an electrode layer, and a protective layer, and low-melting temperature glass frit was used for all layers to allow low-temperature processing. As a substrate for the ceramic heater, Si3N4, which is twice as strong as AlN and has excellent wear resistance, was used. As the electrode material, Ag-Pd, which provides good adhesion to the Si3N4 substrate and high electrical conductivity was used, and MoO3 powder was mixed 8 : 2 to make a paste. The MoO3 adjusts the resistance of the Ag-Pd electrode, thereby supplementing the heater performance. Si3N4 powder and glass frit were used for the protective film layer that protects the electrode, and MoO3 was added to unify the materials between the layers.

정전용량방식 터치패널용 스타일러스펜의 정전특성 연구

이재윤,유시홍,성민호,이성의,Lee, Jae-Yun,Ryu, Si-Hong,Sung, Min-Ho,Lee, Seong-Eui 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.8

A study on capacitive characteristics of stylus pen for touch panel are progressed in this paper. Also the main factors for capacitive sensitivity are studied. Namely, highly sensitive stylus pen which can be applied to capacitive touch panel are studied based on the analysis of materials and process conditions regardless of pattern shapes. Stylus pen was made of PDMS(Poly-Di-Methyl-Siloxane) and conductive metal powders which does not damage the touch panel surface. We tried to get the advantages of both the properties of soft PDMS and conductive metal powders. We found that potential difference of capacitance change with conductivity of the composite materials(PDMS + metal powders) it implies that during touch process, large voltage difference can be caused by the high conductive materials of stylus pen. Stylus pen made by PDMS with mixed with Ag powders which has large conductivity shows more capacitance change of 1 pF than PDMS with other materials of Ni or C powders.

Sputtering공정 적용 Ag-Ti 조성경사형 박막의 구조분석

전용민,유시홍,김민준,이성의 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.12

In this study, a composition-gradient thin film was applied for the formation of intermediate layerof Ti seed layer for an stable electrode stack Ag metal layer. Various composition of Ag-Ti hetero metal layerwere simultaneously deposited by using the sputtering process with Ti and Ag target, respectively. Anintermediate layer was deposited at a gradient composition ratio such as 5:5 and 7:3. In addition, the optimaldeposition conditions were evaluated by confirming the plasma codition such as density of plasma ion, plasmapotential with the Langmuir Probe (Hiden ESPion). Flow rate, power, and composition ratio were optimizedas variables for thin film structures of compositional gradient thin films. In addition, thin film samples wereheat treated at 200 oC, 300 oC, and 400 oC to relieve the residual stress between the interface of laminatedthin films. Under these conditions, a composition-gradient thin film was evaluated by XRD (X-Ray Diffraction,SmartLab Rigaku 9kW), SEM (Scanning Electron Microscope, Nova NanoSEM 450), and EDS (energydispersive X-ray spectroscopy). As a result of the measurement, it was confirmed that interfacial diffusionoccurred due to the composition gradient thin film. When the composition gradient intermediate layer wasapplied to thin film stack, the residual stress increased more than that of single thin film stack. However,after stress relief annealing, residual stress was dramatically decreased compared to single stack.

설계VE에서 최적대안 산정을 위한 평가방법에 관한 연구

김현영,유시홍,최명일,윤소현,현창택 대한건축학회 2000 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.20 No.2

VH(Value Engineering) has recently attracted public attentions as an alternative to improve productivity and effectiveness of construction projects, with its potential to eliminate cost overruns and inefficiencies. The implementation of VE can actually be most effective if executed in the initial planning and design phase, but it has been just limited to the construction phase under the domestic context, and furthermore the absence of practical VE techniques and procedures has been the major obstacles in applying VE in design phase as well. VE is generally implemented through three steps, pre-study, VE study, post-study, but specifically this study was aimed at developing the process far optimum alternative selection and the alternative evaluation method in VE study phase. The methodology chosen to search for evaluations criteria and attributes was questionnaires and experts interviews, and casestudy was performed to validate its usefulness.

Sebum경화 기능형 ZnO powder 특성 연구

전용민,권진구,유시홍,이영철,이성의 대한금속·재료학회 2021 대한금속·재료학회지 Vol.59 No.3

Zinc oxide is transparent inorganic UV absorber and widely used as a sunscreen. But sunscreen on the skin is easily erased by sebum, so zinc oxide with a sebum curing function was studied. In this study, a zinc oxide powder was prepared using zinc chloride and sodium hydroxide via a hydrothermal synthesis method. The process conditions including reaction temperature and sodium hydroxide ratio were determined. Particle size was determined using XRD and SEM, and process tendencies were checked using the gelling test method. When the sodium hydroxide ratio was lower than 58.7 wt%, the gelling time was reduced, and when the temperature was lower than 60 o, the gelling time decreased. ZnO and Simonkolleite confirmed that the gelling time was reduced when the mixture comes out.

강우에 의한 풍력 발전기 블레이드 전연부 침식 시험에 관한 연구

김태원,문기웅,손진혁,김보중,유시홍,윤창번 한국풍력에너지학회 2023 풍력에너지저널 Vol.14 No.3

To improve AEP, wind turbine blade lengths are increasing every year. As the length of blades increases, the blade tip speed also increases. Because of the increased tip speed, the impact energy between the leading edge and raindrops also increases. The increased impact energy is the primary factor contributing to erosion of the blade's leading edge. Blade leading edge erosion reduces aerodynamic performance, increases repair costs, and causes downtime. Therefore, numerous studies are being conducted on protective solutions and RET systems to prevent and delay erosion of the blade's leading edge. However, few institutions in Korea research protective solutions and RET systems. In this study, we aim to develop a laboratory-scale RET system. The developed RET system was based on the ASTM G73-10 standard. As a result of the RET, it was confirmed that the erosion tendency was similar to that of overseas institutions. In addition, the effectiveness of the RET system was verified by a maximum erosion rate of 0.0023 for an epoxy-based protective solution.

Thermal Reflow 공정 적용 Micro Pattern 형상 변화를 통한 광 향상 구조층 연구

성민호,차지민,문성철,유시홍,이성의,Seong, Min-Ho,Cha, Ji-Min,Moon, Seong-Cheol,Ryung, Si-Hong,Lee, Seong Eui 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.5

In this study, the change of optical characteristics was studied according to the micro optical pattern provided by photo lithography followed by thermal reflow process. The shape and luminance variation with micro pattern was evaluated by SEM and spectrometers. Also, we analyzed the luminance characteristics using the 3D-optical simulation (Optis works) program. As a result, we found that the radius of curvature(R) in micro pattern is decreased up to 77%($150^{\circ}C$) compared to the radius of curvature at the condition $100^{\circ}C$, which is caused by efficient reflow of organic material without chemical changes. The highest enhancement of brightness with optimum micro pattern was obtained at the condition of $120^{\circ}C$ reflow process. The brightness gain with optical micro patterns is more than 15% at the condition of R=16.95 um, ${\Theta}=77.14^{\circ}$ compared to original optical source. The results of light simulation with various radius of curvature and side angle of pattern shows the similar result of experiment evaluation of light behavior on optical micro patterns. It is regarded that the more effect on light enhancement was contributed by side angle which is effective factor on light reflection, rather than the curvature of micro-patterns.

Microcavity 적용 광자 발광 소자의 광 추출 향상 연구

이한별,이은혜,성민호,유시홍,이성의,Lee, Han Byul,Lee, Eun Hye,Sung, Min Ho,Ryu, Si Hong,Lee, Seong Eui 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.5

Recently, microcavity is studied to reduce the optical loss of BLU and OLED. In this paper, we suggest applying microcavity to photo-luminescent lamp with plasma discharge technology to meet the display applications for a BLU for LCD. The structure of photo-luminescent lamp consists of SUS foil and ITO glass with microcavity. The opto-electric characteristics of photo-luminescent lamp with microcavity was evaluated. The brightness of photo-luminescent device was increased over $111cd/m^2$ with the adaptation of patterned microcavity at $30{\mu}m$. The 3D optical simulation verified the enhanced light outcoupling when microcavity applied to the device.