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원격조종을 위해 불확실한 시간 지연 측정값을 고려한 모션 추정 방법
최민용(Minyong Choi),정완균(Wan Kyun Chung),최원섭(Wonsub Choi),이상엽(Sangyup Yi),박종훈(Jonghoon Park) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.8
Motion estimation is crucial in a remote control for its convenience or accuracy. Time delays, however, can occur in the problem because data communication is required through a network. In this paper, state estimation problem with uncertain time delayed measurements is addressed. In dynamic system with noise, after taking measurements, it often requires some time until that is available in the filter algorithm. Standard filters not considering this time delays cannot be used since the current measurement is related with a past state. These delayed measurements are solved with augmented extended Kalman filter, and the uncertainty of delayed time is also resolved based on an explicit formulation. The proposed method is analyzed and verified by simulations.
Lee, Junghoon,Kim, Donghyun,Choi, Chang-Hwan,Chung, Wonsub Elsevier 2017 Nano energy Vol.31 No.-
<P><B>Abstract</B></P> <P>Various types of nanoporous anodic aluminum oxide layers and their sealings were studied to enhance the thermal emissivity and hence improve the heat dissipation of aluminum alloy for energy application. Dissipating heat fluxes from the anodized aluminum surfaces were measured using a modified steady-state method and investigated with respect to the various nanoporous morphologies obtained with different anodizing conditions and sealing methods. Results show that the anodized nanoporous oxide layers significantly enhance the thermal emissivity and heat dissipation of aluminum alloy, compared to bare aluminum alloy, and such enhancement is further improved with sealings. A thicker nanoporous oxide layer anodized in oxalic acid results in higher thermal emissivity and better heat dissipation than that in sulfuric acid, showing a darker color which is attributed to the more irregular and disordered pore size and pattern of the nanoporous oxide layer. The nanoporous oxide layer with cold NiF<SUB>2</SUB> or black sealing shows further enhancement in thermal emissivity and heat dissipation, demonstrating the highest enhancement in emissivity up to 0.906 in case of the nanoporous oxide layer anodized in oxalic acid with black sealing, which is seven times greater than that of bare aluminum. The nanoporous oxide layer with black sealing also results in the significant improvement of the cooling efficiency of a heat exchanger system of aluminum alloy by 36.4%, suggesting great energy saving for real energy application.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Porous anodic alumina nanostructures enhance radiative heat transfer of aluminum. </LI> <LI> The sealing of porous nanostructures further enhances the thermal energy transfer. </LI> <LI> Enhancement of the thermal emissivity up to 700% and the heat flux up to 300%. </LI> <LI> Demonstration of the enhancement of heat dissipation for a real heat exchange system. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Ag925의 전기화학적 특성에 미치는 네오디뮴 함량의 영향
신병현(Byung-Hyun Shin),정승진(Seungjin Jung),정원섭(Wonsub Chung) 한국표면공학회 2021 한국표면공학회지 Vol.54 No.2
Ag925, silver with added copper, is popular alloy due to its low price. However, it has a difficult to use because of the low corrosion resistance. In various alloys, neodymium (Nd) works as an element to improve corrosion resistance by reacting with interstitial elements in the alloy. When 1.5 wt. % Neodymium was added to Ag925, the potential on the activated polarization in a potentiodynamic polarization test was increased from -0.15 V to –0.05 V. Ag925 with added neodymium showed the passivation after activation polarization. But When the potential increased around 50 ㎷, the current density is increased to 3 x 10-3. Ag925 with the 1.5 wt. % Nd had the low corrosion rate.
서미희(Mihui Seo),김동현(Donghyun Kim),이정훈(Junghoon Lee),정원섭(Wonsub Chung) 한국표면공학회 2013 한국표면공학회지 Vol.46 No.5
The aim of the present study was to improve the radiative heat dissipation of aluminum alloy, Al 1050. Resin/CuO coating and Cu/CuO composite plating were applied on aluminum alloy to improve the radiative heat dissipation. Resin/CuO coating was made using thermosetting silicon resin and Cu/CuO composite plating was made in pyrophosphate copper plating bath. Radiant heat flux(W/㎡) was measured by self-produced radiant heat measurement device to compare each specimen. The cross section of specimen and chemical bonding of surface were analyzed by FE-SEM, XPS and FT-IR. As a result, radiant heat of Resin/CuO coating was higher than Cu/CuO composite plating due to the adhesion with aluminum plate and the difference in chemical bonding. But, Both of them were higher than aluminum alloy. In order to confirm the result of experiment, aluminum plate, Resin/CuO coating and Cu/CuO composite plating sample were applied LED and measured the LED temperature. As a result, LED temperature of samples were matched previous results and confirmed coated samples were lower about 10 degrees than the aluminum alloy.
복사에너지를 이용한 TIM소재의 방열 특성 향상을 위한 연구
황명원,김도형,정우창,정원섭,Hwang, Myungwon,Kim, Dohyung,Jung, Uoo-Chang,Chung, Wonsub 한국표면공학회 2019 한국표면공학회지 Vol.52 No.2
The aim of this study is to quantitatively demonstrate the possibility of heat transfer by thermal radiation by comparing heat transfer by conventional heat transfer and radiation by radiation. 1) The heat transfer was measured by using filler of TIM material with low thermal conductivity (CuS). As a result, heat transfer was easier than ceramic with high thermal conductivity ($Al_2O_3$ and $Si_3N_4$). 2) The reason for this is thought to be that the infrared wave due to radiation of the air diaphragm has moved easily. 3) From the above results, the heat dissipation of the TIM material indicates the possibility of heat transfer by thermal radiation.
Effect of composite PEO film containing titanium oxides on the corrosion resistance of Al 6061 alloy
Sung, Dahye,Kim, Donghyun,Park, Jung-Hyun,Kim, Yonghwan,Chung, Wonsub Elsevier 2017 Surface & coatings technology Vol.309 No.-
<P><B>Abstract</B></P> <P>Composite plasma electrolytic oxidation (PEO) was carried out to deposit Ti-oxides directly on a substrate of Al 6061 alloy. A TiO<SUB>2</SUB> (anatase)- and Al<SUB>2</SUB>O<SUB>3</SUB>-dense composite PEO film is generated on the substrate, and the corrosion resistance was examined by electrochemical analyses: potentio-dynamic polarization (PP), and electrochemical impedance spectroscopy (EIS) using an equivalent electrical circuit model. In addition, surface and cross-sectional morphologies were observed to confirm the dependence of pore size on treatment time. Using a current density of 10A/dm<SUP>2</SUP> applied for up to 30min, the PEO film produced is denser, more continuous, and has smaller pores in comparison to conventional PEO specimens. In addition, the corrosion resistance observed in the electrochemical tests is enhanced for the composite PEO film in comparison to conventional PEO treatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We fabricated the Ti-oxides composite coating layer on aluminium alloy by PEO process. </LI> <LI> A diffusion resistance was removed by composite PEO with direct deposition of Ti-oxides. </LI> <LI> The size of pores was significantly decreased compared with the conventional PEO. </LI> </UL> </P>