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전병렬,이재복,임성진 慶星大學校 環境問題硏究所 1996 環境硏報 Vol.6 No.1
Handling of waste tire rubber is an environmental problem because the number of automobiles is increasing every year. The reuse of waste tire rubber as adsorption material may be a measure to solve this solid waste problem. The adsorption capacity of waste tire rubber was investigated in this study. Operation factors of adsorption such as temperature, pH, solution concentration, and the adsorption capacity were experimentally evaluated to analyze the applicability of waste tire rubber as adsorption material. The waste tire used in the experiment was obtained from an ordinary passenger vehicle. It was washed, dried and cut into pieces with the diameter of about 0.5 mm. to estimate the adsorption capacity, waste tire pieces were put into an erlenmeyer flask containing the hexavalent chromium solution. The atomic absorption spectrophotometry was conducted with the time interval. During the adsorption test, the sample was stirred at the speed of 30-60 rpm. The results showed that equilibrium adsorption capacity was 335 ㎍ Cr??/g of tire when the operation was in the condition of 20ppm chromium solution at pH 1, the temperature of 30℃, and 2g of tire as adsorption material. The value of pH was the most critical factor in adsorption. The extracted zinc ion was detected. This might come out from ZnO which was used in factory as the vula\canization activator of the rubber. The simulation through the isothermic equation resulted in positive applicability for the adsorption of chromium by shredded waste tire rubber.
Lim, Sung Yul,Ha, Kyungyeon,Ha, Heonhak,Lee, Soo Youn,Jang, Min Seok,Choi, Mansoo,Chung, Taek Dong The Royal Society of Chemistry 2019 Physical chemistry chemical physics Vol.21 No.8
<P>Platinum is still the most active element for the hydrogen evolution reaction (HER); however, it suffers from its scarcity and high cost. Thus, significant efforts have been dedicated to maximize the catalytic activity with less loading. When Pt is utilized at a semiconductor surface, more factors have to be considered. Placing a catalyst directly in contact with a semiconductor supports the extraction of photogenerated minority carriers as well as boosts the catalytic reactions. In addition, a catalyst should be designed with prudence not to interfere in the light path with respect to absorption at the underlying substrate. Herein, we report the development of planar Si-based photocathodes, covered with a native oxide, for the HER, which also satisfy the prerequisites for the use of a three-dimensionally patterned, flower-like Ag-Pt catalyst. The catalyst consisted of nanoparticles of homogeneously alloyed Ag and Pt, fabricated by a galvanic exchange of Pt with Ag. Importantly, these two elements were proven to have their own functionalities. Ag not only contributed to transporting e<SUP>−</SUP> and Had to the Pt for subsequent processes of the HER but also effectively extracted minority carriers by diluting the high work function of Pt, leading to a better Schottky barrier at the catalyst-insulator-semiconductor junction. Furthermore, computational simulation revealed that the proposed catalyst pattern alleviated optical light loss with the increasing catalyst loading compared to the two-dimensional case. Owing to these effects, we could achieve 0.36 V (<I>vs.</I> reversible hydrogen electrode) as an open circuit potential and the near maximum current density of planar p-type Si. The findings in this work suggests deeper insights that could support the design of catalysts for solar-fuel systems.</P>
Lim, Sung Yul,Kim, Yang-Rae,Ha, Kyungyeon,Lee, Jong-Kwon,Lee, Jae Gyeong,Jang, Woohyuk,Lee, Jin-Young,Bae, Je Hyun,Chung, Taek Dong The Royal Society of Chemistry 2015 Energy & environmental science Vol.8 No.12
<P>Hydrogen is in the lime light as a carbon-free alternative energy source due to its high energy conversion efficiency. Solar-driven water splitting is one of the most promising methods for renewable hydrogen production. However, commercialization of a photoelectrochemical hydrogen production system remains a great challenge. One of the emerging concerns is the development of an inexpensive and transparent catalyst, which does not obstruct the light pathways to the semiconductor electrode. Here we report a non-noble metal electrocatalyst for hydrogen evolution, Ni-Mo, which is directly patterned on amorphous Si (a-Si) by light-guided spatially selective electrodeposition without consecutive photolithography processes. A light pattern is illuminated onto the a-Si using a digital micromirror device to commence the photoelectrochemical deposition. The catalyst patterned by the proposed method not only admits sufficient light to a-Si but also enables long distance carrier transport along the inversion layer, as previously observed in crystalline Si (c-Si) photocathodes. This new electrodeposition method enables mask-free patterning on a-Si and is expected to expedite a lower cost, more efficient, and self-biasing integrated photoelectrochemical water-splitting device.</P> <P>Graphic Abstract</P><P>For photoelectrochemical hydrogen production, a non-noble catalyst is directly patterned onto the photocathode using a light-guided electrodeposition technique. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5ee02863a'> </P>
Lim, Sung Yul,Han, Donghyeop,Kim, Yang-Rae,Chung, Taek Dong American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.28
<P>For more efficient photoelectrochemical water splitting, there is a dilemma that a photoelectrode needs both light absorption and electrocatalytic faradaic reaction. One of the promising strategies is to deposit a pattern of electrocatalysts onto a semiconductor surface, leaving sufficient bare surface for light absorption while minimizing concentration overpotential as well as resistive loss at the ultramicroelectrodes for faradaic reaction. This scheme can be successfully realized by 'maskless' direct photoelectrochemical patterning of electrocatalyst onto an SiOx/amorphous Si (a-Si) surface by the light-guided electrodeposition technique. Electrochemical impedance spectroscopy at various pHs tells us much about how it works. The surface states at the SiOx/a-Si interface can mediate the photogenerated electrons for hydrogen evolution, whereas electroactive species in the solution undergo outer-sphere electron transfer, taking electrons tunneling across the SiOx layer from the conduction band. In addition to previously reported long-distance lateral electron transport behavior at a patterned catalyst/SiOx/a-Si interface, the charging process of the surface states plays a crucial role in proton reduction, leading to deeper understanding of the operation mechanisms for photoelectrochemical water splitting.</P>
Numerical analysis of the performance of a tiltable multi-effect solar distiller
Lim, Byung-Ju,Yu, Sang-Seok,Chung, Kyung-Yul,Park, Chang-Dae Elsevier 2018 Desalination Vol.435 No.-
<P><B>Abstract</B></P> <P>This paper proposes a tiltable multiple-effect solar distiller and presents a numerical analysis on its performance. The distiller consists of a glass cover, a number of parallel plates, and seawater-soaked wicks placed in contact with the plates. The wick of the glass cover is designed to be black color to increase the solar energy absorption. A 2-dimensional numerical model of heat and mass transfer was developed to analyze the distiller's optimal operating and design conditions, and a numerical analysis was conducted in each of the four seasons at N30° and E127°. The results show that the TMED can produce the fresh water of 16.6kg/m<SUP>2</SUP> by optimal operation and the performance ratio is 1.44, which is 2.8 times more than that of a basin-type still. The wind reduced the productivity of the distiller due to heat loss from the glass. Although the productivity increased with decrease of inclination angle of the distiller, the optimum value was 40–50° considering deformation of plate and contamination of fresh water. Feeding the same flowrate of 6 ccm to all effects was recommended for convenient and reliable operation. The optimal number of effects was 11 based on annual productivity and manufacturing cost.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Tiltable multiple-effect solar distiller. </LI> <LI> Numerical analysis was performed to find optimum design and operating condition. </LI> <LI> Optimum condition of feeding flowrate, decreasing rate of feeding flowrate, number of effects, and inclination angle </LI> <LI> Effects on wind speed and configuration of the evaporation surface </LI> <LI> Performance ratio is 1.44, which is 2.8 times more than that of a basin-type still. </LI> </UL> </P>
User friendly molecular breeding platform by analyzing soybean genomes
Yul Ho Kim,Tae-Young Hwang,Hyang Mi Park,Seuk Ki Lee,Man Soo Choi,Kwang Ho Jeong,Min Jung Seo,Hong Tai Yun,Sun Lim Kim,Young-Up Kwon,Ik-Young Choi,Ho-Sung Yoon,Suk-Ha Lee,Jong Bhak,Sunghoon Lee 한국육종학회 2012 한국육종학회 심포지엄 Vol.2012 No.07
Resequencing data is actively used for searching QTL or analyzing genetic diversity in the crops. However, the complexity of genome, caused by genome duplication, limits the utility of genome-wide association studies and linkage analyses to identify genes that regulate agronomically valuable traits. Here, we propose a comparative genomics approach based on core or common variation-based recombination blocks (CRB) using single nucleotide variation (SNV) density information. We found that the soybean genomes are assembled with long and distinct CRBs as large as 10Mb. CRB-based comparative genomics enabled us to accurately identify recombination blocks at the whole-chromosome level. We identified the Ih locus that determines the yellow hilum color in soybeans using CRB-based mapping with representative indel markers. These results suggest that the CRB-based comparison method is a promising platform for molecular breeding and map-based cloning.