태양 에너지 수집형 엣지 AIoT 환경에서 엣지 장치의 에너지를 고려한 효율적인 분산 학습 방법

유연태,윤익준,노동건 한국정보과학회 2023 정보과학회논문지 Vol.50 No.8

Solar-powered IoT devices periodically harvest energy and therefore can fundamentally solve the energy limitation of battery-based IoT devices. However, a careful energy consumption policy is required due to the variation in the amount of energy harvested. There is a growing interest in the AI-distributed training models that can improve the quality and performance of training by conducting small training at each edge node and sharing the results with neighbors. However, the straggler node problem may occur in such distributed models, significantly decreasing the overall training speed and exponentially reducing the lifespan of the IoT network due to insufficient energy of specific nodes. This study proposes a technique to prevent the occurrence of straggler nodes as much as possible for efficient AI-distributed training in an AIoT environment composed of solar-powered devices. The proposed scheme uses an approximate computing technique that adapts energy consumption by adjusting the accuracy according to each node’s harvested energy while retaining the minimum accuracy required by the application. Among various approximation computing schemes, this study uses a data-level approximation scheme that adjusts the accuracy by adjusting the sampling rate of the sensing data. The experimental results confirm that the proposed scheme reduces the generation of straggler nodes by efficient and balanced use of each node’s harvested energy.

중유회 소각재로부터 바나듐, 니켈 침출에 관한 기초적 연구

유연태,김병규,박경호,홍성웅 한국자원리싸이클링학회 1995 資源 리싸이클링 Vol.4 No.3

Thc purpose of this study is to develop the efficient process for recovering vanadium and nickel from the incineralionash of the oil fly ash. In this paper, the physical and chemical properties of the incineration ash was examined, and theleaching characteristics of the incineration ash were investigated by water leaching and sulEuric acid leaching tcsls. The incinerationash of oil fly ash was mainly consisted of oxldes such as V,09, V,O,, NaVO,, Ni,(VO,)Z, Fe,O,, CaSO,, SiO,.Thc waler leaching showed low extraction of metallic components, while the sulfunc acid lcaching with high temperahlreand pressure increased the extraction of vanadium and nickcl considerably. For instance, the exlraction rates of the metalllccomponents on the sulfuric acid leaching were 99% for V and 45% for Ni at 90$^{\circ}$C with pH 0.5 H,SO,, and were86% for V and 75% far Ni at ZOO"C(64 psi) with pH 1.0 H-SO,. with pH 1.0 H-SO,. 중유회의 소각재로부터 바나듐과 니켈을 회수할 목적으로 본 연구에서는 중유회 소각재의 물리 화학적 특성 및 침출특성을 조사하였다. 소각재의 물리 화학적 특성은 성분분석, 주사전자현미경에 의한 형태관찰 및 X선 회절실험을 통하여 조사하였고, 소각재중의 바나듐과 니켈의 침출특성은 물과 황산용액에 대하여 행하였다. 실험결과 중유회 소각재의 주요 구성물질은 $V_4$O, $V_2$O4, $NaVO_3$, $Ni_3$($VO_4$)$_2$, $Fe_2$$O_3$, $CaSO_4$, $SiO_2$로, 수용성 물질이 적어 수침출에 의해서는 소량의 바나듐만이 침출되었다. 한편, 황산침출이나 고온고압하에서의 황산침출은 중유회 소각재로부터 바나듐과 니켈을 추출하는데 효과적인 방법이었다. 황산침출의 경우(pH 0.5, 9$0^{\circ}C$) 바나듐과 니켈의 침출율은 각각 99%와 45%였고, 고온고압하의 황산침출의 경우 (pH 1.0, $200^{\circ}C$, 60 psi) 바나듐과 니켈의 침출율은 각각 86%와 75%를 나타내었다.

Au/TiO₂ core-shell 나노입자의 합성에 있어서 Au 나노입자의 분산특성에 미치는 Mercaptoundecanoic acid (MUA)의 피복 효과

유연태,김병규,Yu, Yeon-Tae,Kim, Byoung-Gyu 한국재료학회 2006 한국재료학회지 Vol.16 No.12

Mercaptoundecanoic acid (MUA) has been used to enhance the dispersity of Au nanoparticles in organic solvent and the affinity between the Au nanoparticles surface and titanium dioxide shell in the synthesis of $Au/TiO_2$ core-shell composite nanoparticles. The dispersity of the MUA-coated Au nanoparticles in ethanol aqueous solution with different concentration of $H_2O$ was investigated by UV-Vis. absorption spectrum and the coating amount of MUA was varied from 0.02 mM to 1.0 mM. The MUA-coated Au nanoparticles were highly dispersed in pure $H_2O$ in the wide range of the coating amount of MUA. On the contrary, the MUAcoated Au nanoparticles showed an enhanced stability in the ethanol/$H_2O$=8/2 mixed solution only when the coating amount of MUA was 0.05 mM, and in the ethanol/$H_2O$=7/3 mixed solution when the coating amount of MUA was in the range from 0.02 mM to 0.17 mM. From this systematic study, it can be inferred that the stability and the dispersibility of Au nanoparticles in organic solvents are highly sensitive towards the amount of MUA coating.

[가고 싶은 그곳으로] 드라마 「그대 그리고 나」의 무대로 잘 알려진 영덕 강구항의 바다내음

유연태 새가정사 1998 새가정 Vol.- No.-

WO₃ 피복 석탄회의 광촉매 특성에 미치는 TiO₂의 첨가 효과

유연태,김병규,Yu, Yeon-tae,Kim, Byoung-gyu 한국재료학회 2003 한국재료학회지 Vol.13 No.10

To improve the photocatalyticactivity of $TiO_2$-coated coal fly ash, tungsten hydroxide was doped by impregnation method and was oxidized by heat treatment in temperature ranges of $WO^{\circ}C$ for 2 hrs. The changes of crystal structure and crystal size of $TiO_2$and $WO_3$on coal fly ash were investigated by X-ray diffraction analysis. The crystal structure of titanium dioxide showed only anatase type and $TiO_2$-$WO_3$ compounds appeared in the heat treatment temperature ranges of $500∼600^{\circ}C$. By adding $V_3$in $TiO_2$coated on fly ash, the growth of crystal size of anatase was restrained and the anatase phase was stabilized in temperature ranges of $500∼<800^{\circ}C$. And $WO_3$acted as a trap site of electrons excited from anatase by irradiating UV. The maximum removal efficiency of NO gas for $TiO_2$/$WO_3$-coated coal fly ash was 84% and appeared when the ammonium tungstate of $1.3${\times}$10^{-3}$ M was doped and then heated at $600^{\circ}C$ for 2 hrs.

[가고 싶은 그곳으로] 당진 외목마을과 필경사 - 일출 볼 수 있는 외목마을

유연태 새가정사 1998 새가정 Vol.- No.-

페복제 적하법에 의한 나노 결정 TiO₂ 피복 석탄회의 제조와 광촉매 특성

유연태,최영윤,김병규,Yu, Yeon-Tae,Choe, Yeong-Yun,Kim, Byeong-Gyu 한국재료학회 2002 한국재료학회지 Vol.12 No.5

$TiO_2$-coated fly ash was synthesized by dropping method of coating agent in order to get $TiO_2$ coating layer with high photocatalytic activity on the surface of coal fly ash. The properties of the $TiO_2$ coating layer such as morphology, crystal structure, crystal size and photocatalytic activity were compared with those of the $TiO_2$-coated fly ash prepared by the traditional method of precipitation. $TiCl_4$ aqueous solution was used as a titanium stock solution and $NH_4HCO_3$ was used as a precipitant. The $TiO_2$ coating layer obtained by dropping method of coating agent was more uniform than that coated by precipitation. However, the crystal of $TiO_2$ coated by dropping method of coating agent was easy to grow by heat treatment because of the small primary particle size and bulky morphology, and its photocatalytic activity was consequently lower than that of the $TiO_2$ coated by precipitation. The $TiO_2$ coating layer obtained by both methods had a crystal structure of anatase, and the temperature of phase transformation into rutile was 90$0^{\circ}C$. The minimum crystal size of $TiO_2$ for the highest photocatalytic activity was found to be about 10nm.

피복제 적하법에 의한 Ag 피복 Cu 미립자의 제조 및 광학적 특성

유연태,Yu, Yeon-tae 한국재료학회 2003 한국재료학회지 Vol.13 No.9

Ag-coated Cu particles were prepared by dropping method of coating agent and were evaluated by scanning electron microscope and color difference meter. The shape of Cu particles having obvious crystal plan and edge was changed spherically according to the increase of Ag coating amount. When the Ag coating amount was 50 wt% to Cu particles, the whiteness of Ag-coated Cu particles was almost similar to that of pure Ag particles. Adding $NH_4$OH in reductant solution could increase effectively the whiteness of the Ag-coated particles. The Ag-coated particles having the highest whiteness was obtained when the content of hydrazine in reductant solution was 0.48 M.

[가고 싶은 그 곳으로] 수로 낚시터로 소문난 왕모대포구의 비경을 찾아

유연태 새가정사 1998 새가정 Vol.- No.-

소성블릭 제조를 위한 무연탄 석탄회의 특성 연구

유연태,김병규,최영윤,남철우,이용석,김천순,Yu Yeon-Tae,Kim Byoung-Gyu,Choi Young-Yoon,Nam Chul-Woo,Lee Yeng-Seok,Kim Cheon-Sun 한국자원리싸이클링학회 2004 資源 리싸이클링 Vol.13 No.2

To increase the recycling rate of anthracite fly ash, the properties of anthracite fly ash were compared to that of bituminous fly ash. Especially, the high temperature properties of the fly ash are investigated by using thermal analysis, high temperature microscope and X-ray diffraction analysis for utilizing anthracite fly ash to prepare the calcinated bricks. The average ratio of $A1_2$$O_3$/$SiO_2$ for anthracite is 0.62 and the ratio for bituminous is 0.34. The content of $SiO_2$ in anthracite fly ash was higher than that of bituminous fly ash. The $A1_2$$O_3$ of anthracite fly ash reacted with the $A1_2$$O_3$ in the fly ash and formed new mullite crystal at over $1000^{\circ}C$, so anthracite fly ash showed high fire resistance. And, the fly ash mixtures having kaolin were prepared, and then extruded in vacuum to evaluate the extruding property of anthracite fly ash mixture. The extruding velocity was decrease with increasing the addition amount of fly ash in the mixture, and the maximum addition amount of fly ash that could be extruded was 60 wt%. 무연탄 석탄회의 재활용 향상을 위하여, 무연탄 석탄회의 특성을 유연탄 석탄회의 특성과 비교하였다. 특히, 무연탄 석탄회를 소성블릭의 원료로 활용하기 위하여, 무연탄 석탄회의 고온 특성이 열분석, 고온현미경 및 X선 회절 분석에 의해 조사되었다. 무연탄석탄회의 $A1_2$$O_3$/SiO$_2$ 비는 평균 0.62이고 유연탄 석탄회는 $A1_2$$O_3$/$SiO_2$ 비가 0.34로 무연탄 석탄회 중 A1$_2$$O_3$ 성분의 조성이 높았다. 무연탄 석탄회 중 $SiO_2$는 석탄회 중의 $A1_2$$O_3$와 반응하여 $1000^{\circ}C$의 고온에서 새로운 뮬라이트 결정을 형성하였고, 그 결과 우수한 내화도를 나타내었다. 또한, 무연탄 석탄회의 첨가량 변화에 따른 혼합시료의 압출 성형 특성을 평가하기 위하여 고령토와의 혼합시료가 제조되었고, 무연탄 석탄회 첨가 성형 벽돌의 압출속도는 혼합시료 중 석탄회의 첨가량이 증가할수록 감소하였으며, 압출 성형가능한 무연탄 석탄회의 최대 첨가량은 60wt%이었다.