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Isworo, Yanuar Yudhi(이스워로 야누아르 유디),Jeon, Chung Hwan(전충환) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.춘계 No.-
Thermogravimetric characteristics of some typical coal representing low-high rank coal and include upgraded coal were investigated using a thermogravimetric analyzer under heating rate of 10°C/min to 850°C in air condition. The coal samples were representing low, medium, and high rank coal and include also upgraded coal (ash free coal). Result obtained from this investigation indicated thatcoal rank which is based on calorific value could not be referred as only parameter to judge coal reactivity in term of coal as power generation, and low-rank coal has showed that it could has better reactivity than higher rank coal in tenn of initial temperature. Future research should be conducted to detail other factors in term of coal structure before, during, and after being combusted as parameters caused better performance in coal utilization area.
A Low Power, Low Supply Voltage, and Wide dB-Linear Range Pseudo-Exponential Function Generator
Laksono Widyo Isworo,Cosy Muto,Hiroshi Ochi 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7
A new topology of pseudo-exponential function generator, which features low supply voltage (1.2V), low power (0.3㎽), and wide ㏈-linear range (120 ㏈), is proposed. Its rail-to-rail topology results in an improved implementation of the pseudo-exponential function to achieve wider ㏈-linear range. These features make the pseudo-exponential function generator suitable for realizing very wide gain range variable gain amplifier (VGA). The pseudo-exponential function generator is simulated in 90㎚ CMOS technology and verified by ADS simulation. The comparison between the proposed topology and the reference topology is also presented.
Jeong, Tae-Yong,Isworo, Yanuar Yudhi,Jeon, Chung-Hwan American Chemical Society 2019 Energy & fuels Vol.33 No.9
<P>Petrographic analysis can provide valuable information about pulverized coal used in coal-fired power plants. In this study, petrographic analysis was used to determine the effect of blending on the combustion of low-rank coal from Mongolia and two bituminous coals from Russia. After blending these coals based on their calorific values and combusting them in a drop tube furnace, the unburned combustibles in the char were analyzed. The coal rank, determined from the mean random vitrinite reflectance, was closely correlated with the proportion of each single coal in the blend. Char component analysis showed that the generated char particles were not affected by the coal rank but had a strong relationship with the microlithotype of the raw coal. In contrast, for single coals, the unburned combustibles at equal temperatures were affected by the coal rank. Morphological analysis of the char types revealed that the geometric tendency of each coal was in agreement with the char formed at different temperatures. However, combustion results for the blended samples exhibited somewhat complicated tendencies. The unburned combustibles showed interactions between coals relating to their petrographic properties, such as vitrinite reflectance and char components.</P>
Kim, Gyeong-Min,Lisandy, Kevin Yohanes,Isworo, Yanuar Yudhi,Kim, Jin-Ho,Jeon, Chung-Hwan Elsevier 2018 Fuel Vol.212 No.-
<P><B>Abstract</B></P> <P>The effects of adding ash-free coal (AFC) as a binder on the physical and chemical properties of coke were investigated to understand the mechanism of coke strength increase and to measure CO conversion reactivity. Two AFC samples (AFC_P and AFC_E) were first extracted from Indonesian low-rank coal. Torrefied biomass was also produced from woody biomass for use as an additive to AFC samples. Coke samples were then prepared by adding 3% AFC and 3% AFC + torrefied fuel. The coke strength was investigated by performing indirect tensile tests and <SUP>13</SUP>C NMR analyses. Coke reactivity was examined using thermogravimetric analysis and a coke reactivity test apparatus. The use of AFC as a binder increased the tensile strength of coke between 39% and 48%. Specifically, coke tensile strength was 2.32 MPa with AFC_P and 2.16 MPa with AFC_P + torrefied fuel; and 2.17 MPa with AFC_E and 2.10 MPa with AFC_E + torrefied fuel. The reactivity of the coke containing AFC + torrefied fuel was higher than that of the coke containing AFC alone. The coke produced with AFC_E + torrefied fuel had the highest reaction rate and average CO emission of 257,543 ppm.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effects on coke strength of ash-free coal and torrefied fuel were investigated. </LI> <LI> Added torrefied fuel may realize a reduction in CO<SUB>2</SUB> emissions from steelworks. </LI> <LI> The tensile strength of coke is related to the average number of aromatic rings. </LI> <LI> The reactivity of coke produced using TGA and CRTA via CO concentrations. </LI> </UL> </P>
반탄화 과정이 바이오매스 연료의 구조 및 연소성에 미치는 영향
정종원,김경민,야누아르 유디 이스워로,전충환,JEONG, JONG-WON,KIM, GYEONG-MIN,ISWORO, YANUAR YUDHI,JEON, CHUNG-HWAN 한국수소및신에너지학회 2018 한국수소 및 신에너지학회논문집 Vol.29 No.3
Torrefaction is one of the methods to increase combustion calorific value and hydrophobicity of biomass. In this study, the effects of torrefaction on devolatilization, char reactivity and biomass structure were analyzed. Empty fruit bunch (EFB) and Kenaf biomass were used as fuels to be torrefied in the N2 environment at 200, 250 and $290^{\circ}C$. Devolatilization and char kinetics were analyzed by using TGA and biomass structure was investigated through petrography image. The reactivity showed different trends depending on the torrefaction temperature and biomass structure. The herbaceous biomass, Kenaf, was shown as high reactivity and thin wall structure. On the contrary, the woody biomass, EFB, had relatively low reactivity and thick wall structure.
Petrography 분석을 통한 고휘발 역청탄의 연소율 예측
이지환(Ji-Hwan Lee),이대균(Dae-Gyun Lee),야누아르 유디 이스워로(Yanuar Yudhi Isworo),전충환(Chung-Hwan Jeon) 한국연소학회 2021 한국연소학회지 Vol.26 No.1
The purpose of this study is to predict the combustion rate of high-volatile bituminous coal which is one of the important factors in determining the combustion conditions of a power plant. A method of predicting the combustion rate was proposed by integrating the petrography analysis elements related to the combustion rate. Since inertinite had a major effect on the combustion rate, it was possible to predict the combustion rate basically through the inertinite fraction, and petrofactor A was proposed by considering the Vitrinite reflectance value, and more accurate prediction was possible. Petrofactors B and C were proposed by additionally considering the standard deviation of vitrinite reflectance and the effect of liptinite to petrofactor A. The combustion rate could be more accurately predicted. Finally, petrofactor D was proposed considering all the previous factors, and the combustion rate was most accurately predicted.