• IEIE Transactions on Smart Processing and Computing
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• v.6 no.1
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• pp.66-70
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• 2017

Radioactive materials are used in medicine, non-destructive testing, and nuclear plants. Source localization is especially important during nuclear decommissioning and decontamination because the actual location of the radioactive source within nuclear waste is often unknown. The coded-aperture imaging technique started with space exploration and moved into X-ray and gamma ray imaging, which have imaging process characteristics similar to each other. In this study, we simulated $21{\times}21$ and $37{\times}37$ coded aperture collimators based on a modified uniformly redundant array (MURA) pattern to make a gamma imaging system that can localize a gamma-ray source. We designed a $21{\times}21$ coded aperture collimator that matches our gamma imaging detector and did feasibility experiments with the coded aperture imaging system. We evaluated the performance of each collimator, from 2 mm to 10 mm thicknesses (at 2 mm intervals) using root mean square error (RMSE) and sensitivity in a simulation. In experimental results, the full width half maximum (FWHM) of the point source was $5.09^{\circ}$ at the center and $4.82^{\circ}$ at the location of the source was $9^{\circ}$. We will continue to improve the decoding algorithm and optimize the collimator for high-energy gamma rays emitted from a nuclear power plant.

• Journal of Forest and Environmental Science
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• v.33 no.3
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• pp.226-232
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• 2017

Dhup (Canarium resiniferum) is an economically and aesthetically important rare native tree species of Bangladesh. In natural condition 78.5-98.7% seeds do not germinate due to inhibition by hard seed coat, seed predation and unfavorable environmental conditions. A study was conducted in the Seed Research Laboratory and nursery of Institute of Forestry and Environmental Sciences, Chittagong University, Bangladesh in 2013 to find out appropriate pre-sowing treatments for maximizing germination and initial seedling growth. Eleven pre-sowing treatments were provided in both the seeds sown in polybags and seeds sown in propagator house. Results revealed that, germination started at first (after 20 days of seed sown) in seeds immersed in water at room temperature for 24 hours and germination completed within 38 days. Significantly higher (p<0.05) germination percentage (33%), germination energy (16.7%), plant percent (33%) and germination value (0.4) was found with seeds immersed in water at room temperature for 24 hours. Seedling height measured at three, four and five months after the seed germination in case of seeds treated by immersion in water for 24 hours was also greater than others. Therefore, pre-sowing treatment by immersion in water at room temperature for 24 hours was more effective in germination and production of quality vigor seedlings of Dhup.

• Journal of Forest and Environmental Science
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• v.36 no.1
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• pp.25-36
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• 2020

Area exclosure is a widely practiced intervention of restoring degraded lands though its impact in sequestering terrestrial and soil carbon is scanty. The study was initiated to investigate the effect of exclosure of different ages on carbon sequestration potential of restoring degraded dryland ecosystems in eastern Tigray, northern Ethiopia. Twelve plots each divided into three layers were randomly selected from 5, 10 and 15 years old exclosures and paired adjacent open grazing land. Tree and shrub biomasses were determined using destructive sampling while herb layer biomass was determined using total harvest. The average total biomass obtained were 13.6, 24.8, 27.1, and 55.5 Mg ha^-1 for open grazing, 5 years, 10 years, and 15 years exclosures respectively. The carbon content of plant species ranged between 48 to 53 percent of a dry biomass. The total carbon stored in the 5 years, 10 years and 15 years age exclosures were 39 Mg C ha^-1, 46.3 Mg C ha^-1, and 64.6 Mg C ha^-1 respectively while in the open grazing land the value was 24.7 Mg C ha^-1. Carbon stock is age dependent and increases with age. The difference in total carbon content between exclosures and open grazing land varied between 14.3-40 Mg C ha^-1. Although it is difficult to extrapolate this result for a longer future, the average annual carbon being sequestered in the oldest exclosure was about 2.7 Mg C ha^-1 yr^-1. In view of improving degraded area and sequestering carbon, area exclosures are promising options.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.6
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• pp.447-456
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• 2007

Suspended particles behavior when they go through a vertical riser with heat transfer is of significant concern to system designers and operators in pneumatic transport, various processes such as in chemical, pharmaceutical and food industries. When it comes with the energy system, that knowledge is critical to the reliable design practices of related equipment as heat exchangers, especially in the phase of system scale-up. Without haying a good understanding of the related physics, many scale-up practices based on their pilot plant experience suffer from unexpected behaviors and problems of unstable fluidization typically associated with excessive pressure drop, pressure fluctuation and even unsuccessful particle circulation. In the present study, we try to explain the observed phenomena with related physics, which may help understanding of our unanswered experiences and to provide the designers with more reliable resources for their work. We selected hot exhaust gas with solid particle that goes through a heat exchanger riser as our model to be considered. The effect of temperature change on the gas velocity, thermodynamic properties, and eventually on the particles motion behavior is reviewed along with some heat transfer analyses. The present study presents an optimal riser length at full scale under given conditions, and also defines the theoretical limiting length of the riser. The field data from the numerical analysis was validated against our experimental results.

• Journal of Environmental Science International
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• v.23 no.6
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• pp.1037-1047
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• 2014

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/tandem mass spectrometry (GC/MS-MS) has been developed, allowing the simultaneous multi-analyte determination of seven UV filters in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 12.9%). The extraction efficiencies were above 84% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1~8.6 ng/L and 6.8~27.5 ng/L, respectively. The developed method offers the ability to detect 8 UV filters at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 7 UV filters except of benzophenone (BP). The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.5
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• pp.48-57
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• 2000

This paper is dealing with the fundamental properties of planting concrete, replacing the existing cover concrete on the roof of a building. This study is to find out the physical characteristics of the planting concrete and rearing characteristics of the grass throughout the modeling experimental materials. As the results of the experiment, the physical properties of planting concrete show the following results; when the paste to aggregate ratio is 0.2~ 0.4, voids volume : 30~17%, unit weight: 1,710~2,010kg/m3, compressive strength : 45~145kgf/$\textrm{cm}^2$, its pH is more than 11, but is reduced to the proper degree for planting after being neutralized. Kentucky bluegrass covered with planting concrete is grown well. The planting concrete used with blast furnace slag cement shows a better properties at the height, the width and the covering rate by 1.1cm, 0.5mm and 7%, respectively, than those used with ordinary portland cement. Also, the less the paste to aggregate ratio is, the better the plant grows. The orders of the effects of temperature control are as follows; the system of planting concrete with grass>the system of planting concrete without grass>the system of mixed soil>the existed roof system. In case, the planting concrete is placed to the roofs of buildings instead of normal concrete slab, and a number of favorable effect can be expected such as the improvement os environmental factors, the reduction of construction cost, the saving of energy and the reduction of environment load. The future research on the change of a variety of the aggregate conditions and the application of the practical structures should be made, and also the research of the endurance also be performed.

• KIEAE Journal
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• v.13 no.5
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• pp.89-96
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• 2013

Green roofs can reduce surface water runoff, provide a habitat for wildlife moderate the urban heat island effect, improve building insulation and energy efficiency, improve the air quality, create aesthetic and amenity value, and preserve the roof's waterproofing. Green roofs are mainly divided into three types : intensive, simple-intensive, and extensive. Especially, extensive roof environment is a harsh one for plant growth; limited water availability, wide temperature fluctuations, high exposure to wind and solar radiation create highly stressed environment. This study, aimed at extensive green roof, was carried out on the rooftop of the library at Seoul Women's Univ. from October to November, 2012 and from March to August, 2013. To suggest the most effective vegetation model for biodiversity and heat island mitigation, surface temperatures were monitored by each vegetation model. We found that herbaceous plants of Aster sphathulifolius, Aceriphyllum rossii and Belamcanda chinensis, shrub of Syringa patula 'Miss Kim', Thymus quinquecostatus var. japonica, Sedum species can mixing each other. Among them, the vegetation models including Sedum takesimense, Aster sphathulifolius, Thymus quinquecostatus var. japonica was more effective on the surface temperature mitigation, because the species have the tolerance and high ratio of covering, and also in water. Especially, in the treatment of bark mulching, they helped to increase the temperature of vegetation models. In the case of summer, temperature mitigation of vegetation models were no significant difference among vegetation types. Compared to surface temperature of June, July and August were apparent impact of temperature mitigation, it shows that temperature mitigation are strongly influenced by substrate water content.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.215-221
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• 2016

In this study, the utilization of the by-products of various industries was examined using raw materials of CSA high-functional cement such as coal bottom ash, red mud, phosphate gypsum, etc. Technology to improve energy efficiency and reduce $CO_2$ was developed as part of the manufacturing process; this technology included lower temperature sintering ($150{\sim}200^{\circ}C$) than is used in the OPC cement manufacturing process, replacement of CSA cement with the main raw material bauxite, and a determination of the optimum mix condition. In order to develop CSA cement, a manufacturing system was established in the Danyang plant of the HANIL Cement Co. Ltd., in Korea. About 4,200 tons of low purity expansion agent CSA cement (about 16%) and about 850 tons of the lime-based expansion agent dead burned lime (about 8%) were produced at a rate of 60 tons per hour at the HANIL Cement rotary kiln. To improve the OPC cement properties, samples of 10%, 13%, and 16% of CSA cement were mixed with the OPC cement and the compressive strength and length variation rate of the green cement were examined. When green cement was mixed with each ratio of CSA cement and OPC cement, the compressive strength was improved by about 30% and the expansibility of the green cement was also improved. When green cement was mixed with 16% of CSA cement, the compressive strength was excellent compared with that of OPC cement. Therefore, this study indicates the possibility of a practical use of low-cost CSA cement employing industrial wastes only.

• Journal of Environmental Science International
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• v.25 no.11
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• pp.1493-1498
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• 2016

The efficiencies of Gang-Byeon sewage treatment facilities, which are based on GPS-X modelling, were analysed and used to design recycle water treatment processes. The effluent of an aeration tank contained total kjeldahl nitrogen (TKN) of 1.8 mg/L with both C-1 and C-2 conditions, confirming that most ammonia nitrogen ($NH_3{^+}-N$) was converted to nitrate nitrogen ($NO_3{^-}-N$). The concentrations of $NH_3{^+}-N$ and $NO_3{^-}-N$ were found to be 222.5 and 227.2 mg/L, respectively, with C-1 conditions and 212.2 and 80.4 mg/L with C-2 conditions. Although C-2 conditions with higher organic matter yielded a slightly higher nitrogen removal efficiency, sufficient denitrification was not observed to meet the discharge standards. For the total nitrogen (T-N) removal efficiency, the final effluent concentrations of T-N were 293.8 mg/L with biochemical oxygen demand (BOD) of 2,500 mg/L, being about 1.5 times lower than that (445.3 mg/L) with BOD of 2,000 mg/L. Therefore, an external carbon source to increase the C/N ratio was required to get sufficient denitrification. During the winter period with temperature less than $10^{\circ}C$, the denitrification efficiency was dropped rapidly even with a high TKN concentration (1,500 mg/L). This indicates that unit reactors (anoxic/aerobic tanks) for winter need to be installed to increase the hydraulic retention time. Thus, to enhance nitrification and denitrification efficiencies, flexible operations with seasons are recommended for nitrification/anoxic/denitrification tanks.

• Journal of the Ergonomics Society of Korea
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• v.29 no.3
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• pp.383-391
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• 2010

The present study evaluated a preliminary control room (CR) design of radioactive waste facility using the $JACK^{(R)}$ human simulation system. Four digital humanoids ($5^{th}$, $50^{th}$, $95^{th}$, and $99^{th}$ percentiles) were used in the ergonomic evaluation. The first three were selected to represent 90% of the target population (Korean males aged 20 to 50 years) and the last to reflect the secular trend of stature for next 20 years in South Korea. The preliminary CR design was assessed by checking its compliance to ergonomic guidelines specified in NUREG-0700 and conducting an in-depth ergonomic analysis with a digital prototype of the CR design and the digital humanoids in terms of postural comfort, reachability, visibility, and clearance. For identified design problems, proper design changes and their validities were examined using JACK. A revised CR design suggested in the present study would contribute to effective and safe operations of the CR as well as operators' health in the workplace.