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Transparent Flexible Heater Using Conductive Nanomaterials
Duckjong Kim(김덕종),Seung-Ryeol Kim(김승렬) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Thin tin-doped indium-oxide (ITO) films have been used as transparent film heaters in various applications requiring fast securement of a clear view. However, Indium is rare and its price fluctuates due to market demand. To make a high quality ITO film, relatively high temperature process is required. In addition, due to brittleness of ITO, ITO cannot be used in any applications requiring mechanical flexibility. To overcome the limit of the ITO film heater, several electrically conductive nanomaterials have been tried. However, since each nanomaterial has its own advantages and disadvantages, satisfying various requirements from industry has so far been almost impossible. Here, we present a high-performance transparent film heater based on a hybrid of carbon nanotubes and silver nanowires. The new hybrid film shows a marked advance in haze reduction and an improvement in the flexibility of the silver nanowire film while maintaining excellent electrical conductivity. We demonstrate sufficient temperature rise even at low voltages and long-term stability of the new film heater. This study shows possibility of new high performance transparent film heater based on hybrid of nanomaterials and the film heater could be widely used in various fields requiring both high electrical conductivity and excellent transparency.
Interlayer Coupling of Heat Transport in Suspended Graphene
Duckjong Kim(김덕종),Yun Hwangbo(황보윤),Jae-Hyun Kim(김재현) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Graphene is now in spotlight due to excellent physical properties. Due to the extremely small thickness of the monolayer graphene, if the excellent physical properties are maintained regardless of the system size in the field has been a key question for practical applications. Here, we investigate the thermal conduction in few-layer graphene suspended over holes with specified diameter and try to answer the question in terms of the phonon transport. Our results show that the graphene with 2 or more layers shows characteristics of bulk materials in terms of thermal conduction and that the interlayer coupling must be the key mechanism yielding the intrinsic property.
김덕종(Duckjong Kim),김재윤(Jae Yun Kim),박상진(Sang-Jin Park),허필우(Pil Woo Heo),윤의수(Eui Soo Yoon) 한국유체기계학회 2003 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this work, a continuous-flow micro-PCR system is systematically designed. From the numerical simulation based on the finite volume method, adapting oneself to a new environmental temperature without an external temperature controller is shown to be possible and a cooler as well as a heater is shown to be necessary to obtain three individual temperature zones for polymerase chain reaction. In addition, appropriate geometry of a heat sink for the cooler is determined by using a compact modeling method, the porous medium approach.
Flow Properties of Micro Column Packed with Perfusive Particles
김덕종(Duckjong Kim),황윤욱(Yun Wook Hwang),박상진(Sang-Jin Park),허필우(Pil Woo Heo),윤의수(Eui Soo Yoon) 한국유체기계학회 2005 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this work, perfusive particles are used to form a micro column in a microfluidic chip and flow properties of the micro column are investigated. The packing flow velocity and the column/particle size ratio are shown to be important parameters affecting the packing density of the micro column. Experimental results show that the effect of the column/particle size ratio on the flow resistance of the micro column is negligible. This contrasts with previous works on the effect of the column/particle size ratio on the total pressure drop across the column.
김덕종(Duckjong Kim),허필우(Pil Woo Heo),박상진(Sang-Jin Park),김재윤(Jae Yun Kim),윤의수(Eui Soo Yoon) 한국유체기계학회 2003 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this work, mixing phenomena in the mixing chamber of a ultrasonic micromixer are analyzed through an analytical approach. A simplified 2-dimensional model for the ultrasonic micromixer is presented. Analytical solutions for fluid flow induced by ultrasonic waves are obtained through successive approximations method. From simulation results on thermal diffusion in the mixing chamber, effects of relative location, size, and vibration frequency of a piezoelectric material and aspect ratio of the mixing chamber on mixing performance of the ultrasonic micromixer are investigated. Finally, design guidelines for the ultrasonic micromixer are suggested based on the parametric study.
Manifold Design for Uniform Flow Distribution to Parallel Microchannels
duckjong Kim(김덕종),Seok Ho Yoon(윤석호),Jun Seok Choi(최준석) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
For efficient scale up of microchannel devices, uniform flow distribution to parallel microchannels is very important. In the present work, a dimensionless geometric parameter indicating the optimal manifold configuration is derived through a numerical parametric study and validated by micro particle image velocimetry. It is clearly shown that the flow uniformity is maximized when the dimensionless parameter is about 0.8. This study presents a simple and systematic design methodology for a uniform flow distribution to multiple microchannels operating in parallel.