• Journal of Korean Society for Atmospheric Environment
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• v.24 no.E1
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• pp.1-11
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• 2008

Mercury (Hg), which is mainly emitted from coal-fired power plants, remains one of the most toxic compounds to both humans and ecosystems. Hg pollution is not a local or regional issue, but a global issue. Hg compounds emitted from anthropogenic sources such as coal-fired power plants, incinerators, and boilers, can be transported over long distances. Since the last decade, many European countries, Canada, and especially the United States, have focused on technology to control Hg emissions. Korea has also recently showed an interest in managing Hg pollution from various combustion sources. Previous studies indicate that coal-fired power plants are one of the major sources of Hg in Korea. However, lack of Hg emission data and feasible emission controls have been major obstacles in Hg study. In order to achieve effective Hg control, understanding the characteristics of current Hg sampling methods and control technologies is essential. There is no one proven technology that fits all Hg emission sources, because Hg emission and control efficiency depend on fuel type, configuration of air pollution control devices, flue gas composition, among others. Therefore, a broad knowledge of Hg sampling and control technologies is necessary to select the most suitable method for each Hg-emitting source. In this paper, various Hg sampling methods, including wet chemistry, dry sorbents trap, field, and laboratory demonstrated control technologies, and international regulations, are introduced, with a focus on coal-fired power plants.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.921-927
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• 1995

Peach pulp was separated into serum and insoluble pulp by centrifugation at 11,000 rpm for 10 min. The serum portion was concentrated at $50{\sim}55^{\circ}C$ and $30{\sim}50\;mmHg$ with aroma recovery. Vapor generated at the early stage of vacuum evaporation was condensed and taken as aroma fractions: AR-1($0{\sim}5%$), AR-2($5{\sim}10$), AR-3($10{\sim}15%$), AR-4($15{\sim}20%$). Dynamic headspace concentration method was used to trap volatile compounds in aroma fractions and identification of aroma compounds was made by GC/MS. The yield of serum separated from peach pulp was 70.5% and the serum fraction contained the most of aroma compounds. Thirty-one aroma compounds, including ethylene, benzaldehyde, l-limonene and ${\gamma}-dodecalactone$ were identified. The efficiency of aroma recovery was reduced, as the recovery time was extended, as indicated by less peak numbers and peach areas of aroma fractions.

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.752-760
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• 2018

The lowering of temperature for combustion of diesel particulate matters (or diesel soot) is one of the important tasks in automotive industry that is searching for a way to meet up "high-fuel efficiency, low-emission" standard. In this study, it was discussed how the use of ozone over platinum-based catalyst promotes a low-temperature soot oxidation occurred at $150^{\circ}C$. The use of platinum catalyst did not increase oxidation rate largely but was very effective in improving the selectivity of carbon dioxide. The pre-oxidation of NO into $NO_2$ using ozone was rather crucial in improving the oxidation rate of soot at $150^{\circ}C$.

• Membrane and Water Treatment
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• v.6 no.1
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• pp.1-13
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• 2015

The modification of ultrafiltration membranes with carbon nanotube (CNT) buckypaper on fouling control was investigated. Two types of commercially available flat-sheet membranes were used: PS35 and PES900C/D (PES) (the PS35 membranes were hydrophilic with a molecular weight cutoff of 20 kDa, and the PES membranes were hydrophobic with a molecular weight cutoff of 20 kDa). The CNT buckypaper modified ultrafiltration membranes were prepared by filtering a CNT suspension through the flat-sheet membrane in a dead-end ultrafiltration unit. After modification, the pure water flux of PES was significantly increased, while the pure water flux of PS35 was decreased. The properties of the CNT modified membranes were also investigated. Considering the antifouling properties, pure water flux of the modified membrane, and the stability of CNT buckypaper layer on the membrane surface, ethanol solution with a concentration of 50 wt.%, multi-walled carbon nanotubes (MWCNTs) with a larger diameter (30-50 nm), and the CNT loading with $7.5g/m^2$ was selected. The CNT buckypaper on the surface of ultrafiltration membranes can trap the pollutants in sewage effluent and prevent them reaching the surface of virgin membranes. Water quality analysis showed that the effluent quality of the modified membrane was obviously improved. The removal efficiency of humic acid and protein-like matters by the modified membrane was significant. These results indicate the potential application of the CNT buckypaper layer modified membranes in the field of wastewater reclaim.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.2
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• pp.105-113
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• 2017

Recently the direct injection diesel engine is the most efficient one available for road vehicles, so this fundamental advantage suggests the compression injection diesel engine are a wise choice for future development efforts. The compression ignition diesel engine, with its bigger compression ratios if compared to the SI engine, offers a higher thermodynamic efficiency, also additionally the diesel engine with its less pumping losses due to the throttled intake charge as in a SI engine has higher fuel economy. But the largest obstacle to the success of this engine is meeting emission standards for Nitric oxides and particulate matter while maintain fuel consumption advantage over currently available engines. Thus its use should be largely promoted, however, diesel engine emits more Nitric oxides and particulate matter than other competing one. There has been a trade-off between PM and NOx, so efforts to reduce NOx have increased PM and vice versa, but trap change this situation and better possibility emerge for treating NOx emission with engine related means, such as injection timing, equivalence ratio, charge composition, and engine speed. The common rail direct injection system is able to adjust the fuel injection timing in a compression ignition engine, so this electronically controlled injection system can reduce the formation of NOx gas without increase in soot. In this study it is designed and used the engine test bed which is installed with turbocharge and intercooler. In addition to equipped using CRDI by controlling injection timing with mapping modulator, it has been tested and analyzed the engine performance, combustion characteristics, and exhaust emission as operating parameters.

• Plant Breeding and Biotechnology
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• v.6 no.4
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• pp.313-320
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• 2018

Rice is the staple food of more than 50% of the world population. Cultivated rice has the AA genome (diploid, 2n = 24) and small genome size of only 430 megabase (haploid genome). As the sequencing of rice genome was completed by the International Rice Genome Sequencing Project (IRGSP), many researchers in the world have been working to explore the gene function on rice genome. Insertional mutagenesis has been a powerful strategy for assessing gene function. In maize, well characterized transposable elements have traditionally been used to clone genes for which only phenotypic information is available. In rice endogenous mobile elements such as MITE and Tos have been used to generate gene-tagged populations. To date T-DNA and maize transposable element systems have been utilized as main insertional mutagens in rice. The Ac/Ds system offers the advantage of generating new mutants by secondary transposition from a single tagged gene. To enhance the efficiency of gene detection, advanced gene-tagging systems (i.e. activation, gene or enhancer trap) have been employed for functional genomic studies in rice. Internationally, there have been many projects to develop large scales of insertional mutagenized populations and databases of insertion sites has been established. Ultimate goals of these projects are to supply genetic materials and informations essential for functional analysis of rice genes and for breeding using agronomically important genes. In this report, we summarize the current status of Ac/Ds-mediated gene tagging systems that has been conducted by collaborative works in Korea.

• Journal of Forest and Environmental Science
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• v.38 no.2
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• pp.128-132
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• 2022

Wild boars (Sus scrofa) not only cause crop damage and human casualties, but also facilitate the spread of many infectious diseases in domestic animals and humans. To determine the efficiency of a fencing system in blocking the movement of wild boars, long-term monitoring was performed in a fenced area in Bukhansan National Park using camera traps. Upon monitoring for a period of 46 months, there was a 72.6% reduction in the number of wild boar appearances in the fence-enclosed area, compared to that in the unenclosed area. For 20 months after the fence installation, the blocking effect of the fence was effective enough to reduce the appearance of wild boars by 92.6% in the fence-enclosed area, compared to that in the unenclosed area. The blocking effect of the fence remained effective for 20 months after its installation, after which its effectiveness decreased. Maintaining a fence for a long time is likely to lead to habitat fragmentation. It can also block the movement of other wild animals, including the endangered species - the long-tailed goral. This study suggests a 20-month retention period for the fences installed to inhibit the movement of wild boars in wide forests such as Gangwon-do in South Korea. To identify how long the blocking effect of the fences lasts, further studies are needed focusing on the length and height of the fence, and the conditions of the ground surface.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.1
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• pp.1-8
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• 2022

RISC-V is an open-source instruction set architecture which has a simple base structure and can be extensible depending on the purpose. In this paper, we designed a small and low-power 32-bit RISC-V processor to establish the base for research on RISC-V embedded systems. We designed a 2-stage pipelined processor which supports RISC-V base integer instruction set except for FENCE and EBREAK instructions. The processor also supports privileged ISA for trap handling. It used 1895 LUTs and 1195 flip-flops, and consumed 0.001W on Xilinx Zynq-7000 FPGA when synthesized using Vivado Design Suite. GPIO, UART, and timer peripherals are additionally used to compose the system. We verified the operation of the processor on FPGA with FreeRTOS at 16MHz. We used Dhrystone and Coremark benchmarks to measure the performance of the processor. This study aims to provide a low-power, high-efficiency microprocessor for future extension.

• Journal of Korea Soil Environment Society
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• v.2 no.1
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• pp.73-81
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• 1997

Retention ponds have been dug along some of the motorways to control water flow during rainstorms and to minmize environmental pollution. A retention pond located at Les Ardilleres about 20km South of Orleans along the A-71 motorway has been selected to evaluate the effectiveness of such a pond as a trap for heavy metals. Based on the "index of geoaccumulation" and the "enrichment factor" normalized to Fe introduced by Muller in 1979 and by Helz in 1976, respectively, the degree of contamination by heavy metals for the roadside soil and the settling particles was evaluated. As expected, the contamination was very severe in the roadside soil, while it was not so great in the settling particles. Using these methods, cadmium anomaly was traced in the settling particles of the retention pond, their occurrence being attributed partly to natural and partly to anthropogenic pollution. The estimated input of heavy metals associated with settling particles to the pond was 0.9 g/day Pb, 2.1 g/day Zn and 6mg/day Cd. A tentative mass balance of Pb and Zn originated by motor vehicles suggested that only 5 to l1% of heavy metals deposited on the surface of the motorway is carried to the retention pond by runoff water ; suggestions are made to improve their efficiency.ve their efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.269-275
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• 2017

$NO_X$ reducing technique such as LNT, LNC, and selective catalytic reduction (SCR) have been developed and applied, especially on heavy-duty vehicles. However, it is expected that $NO_X$ reduction techniques will also be applied to diesel passenger vehicles. The urea-SCR system is receiving attention as the most effective $NO_X$ reduction technology without a fuel penalty. Thus, many advanced countries are developing this technology. The urea-SCR system sprays an aqueous urea solution that separates $NO_X$ into $N_2$ and $H_2O$, which are harmless and emitted into the atmosphere. The urea injected in front of the SCR catalyst should be changed to 100％ $NH_3$, which is required for $NO_X$ reduction in the SCR system to maximize the reduction efficiency. The purpose of this study was to determine the basic data for the urea-SCR system to maximize the $NO_X$ reduction efficiency by understanding the $NO_X$ reduction characteristics in a real passenger vehicle to comply with the post EURO-6 emission regulation.