• Tunnel and Underground Space
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• v.33 no.6
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• pp.534-546
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• 2023

If the disc cutter is excessively worn or damaged, it becomes incapable of rotating and efficiently cutting rockmass. Therefore, it is important to appropriately manage the replacement cycle of the disc cutter based on its degree of wear. In general, the replacement cycle is determined based on the results of manual inspection. However, the manual measurements has issues related to worker safety and may lead to inaccurate measurement results. For these reasons, some foreign countries are developing the real-time measurement system of disc cutter wear by using different sensors. The ultrasonic sensors, eddy current sensors, magnetic sensors, and others are utilized for measuring the wear amount of disc cutters. In this study, the applicability of eddy current sensors for real-time measurement of wear amount in TBM disc cutters was evaluated. The distance measurement accuracy of the eddy current sensor was assessed through laboratory tests. In particular, the accuracy of eddy-current sensor was evaluated in various environmental conditions within the cutterhead chamber. In addition, the measurement accuracy of the eddy current sensor was validated using a 17-inch disc cutter.

• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.393-405
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• 2021

With increasing anthropogenic emission sources, air pollutants are emerging as a severe environmental problem worldwide. Accordingly, the importance of landscape trees is emerging as a potential solution to reduce air pollutants, especially in urban areas. This study quantified and compared NO₂ and SO₂ reduction abilities of ten major landscape tree species and analyzed the relationship between reduction ability and physiological and morphological characteristics. The results showed NO₂ reduction per leaf area was greatest in Cornus officinalis (19.81 ± 3.84 ng cm^-2 hr^-1) and lowest in Pinus strobus (1.51 ± 0.81 ng cm^-2 hr^-1). In addition, NO₂ reduction by broadleaf species (14.72 ± 1.32 ng cm^-2 hr^-1) was 3.1-times greater than needleleaf species (4.68 ± 1.26 ng cm^-2hr^-1; P < 0.001). Further, SO₂ reduction per leaf area was greatest in Zelkova serrata (70.04 ± 7.74 ng cm^-2 hr^-1) and lowest in Pinus strobus (4.79 ± 1.02 ng cm^-2 hr^-1). Similarly, SO₂ reduction by broadleaf species (44.21 ± 5.01 ng cm^-2 hr^-1) was 3.9-times greater than needleleaf species (11.47 ± 3.03 ng cm^-2 hr^-1; P < 0.001). Correlation analysis revealed differences in NO₂ reduction was best explained by chlorophyll b content (R² = 0.671, P = 0.003) and SO₂ reduction was best described by SLA and length of margin per leaf area (R² = 0.456, P = 0.032 and R² = 0.437, P = 0.001, R² = 0.872, P < 0.001, respectively). In summary, the ability of trees to reduce air pollutants was related to photosynthesis, evapotranspiration, stomatal conductance, and leaf thickness. These findings highlight effective reduction of air pollutants by landscaping trees requires comprehensively analyzing physiological and morphological species characteristics.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.313-327
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• 2013

In the study, three-dimensional geostatistical simulations on McMurray Formation which is the largest oil sand reservoir in Athabasca area, Canada were performed, and the optimal site for steam assisted gravity drainage (SAGD) was selected based on the predictions. In the selection, the factors related to the vertical extendibility of steam chamber were considered as the criteria for an optimal site. For the predictions, 110 borehole data acquired from the study area were analyzed in the Markovian transition probability (TP) framework and three-dimensional distributions of the composing media were predicted stochastically through an existing TP based geostatistical model. The potential of a specific medium at a position within the prediction domain was estimated from the ensemble probability based on the multiple realizations. From the ensemble map, the cumulative thickness of the permeable media (i.e. Breccia and Sand) was analyzed and the locations with the highest potential for SAGD applications were delineated. As a supportive criterion for an optimal SAGD site, mean vertical extension of a unit permeable media was also delineated through transition rate based computations. The mean vertical extension of a permeable media show rough agreement with the cumulative thickness in their general distribution. However, the distributions show distinctive disagreement at a few locations where the cumulative thickness was higher due to highly alternating juxtaposition of the permeable and the less permeable media. This observation implies that the cumulative thickness alone may not be a sufficient criterion for an optimal SAGD site and the mean vertical extension of the permeable media needs to be jointly considered for the sound selections.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.432-438
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• 2013

A study was conducted to examine the effect of maturity and precooling ($60%/0^{\circ}C$ and $80%/4^{\circ}C$), and light illumination on the storage life of 'Maehyang' strawberry meant for export. Fruits at 60% and 80% ripened stage were harvested from a commercial greenhouse in Jinju on April 3, 2012. Harvested fruits were transported to the precooling system within 30 minutes. Transported fruits were precooled the $4^{\circ}C$ for 2 hours and $0^{\circ}C$ for 5 hours by a forced draft cooling system, and then stored at $6^{\circ}C$. During the storage, the fruits were examined for their changes in hardness, soluble solid content, quality grade, acidity, Hunter value, weight loss, and the incidence of gray mold (Botrytis cinerea) at an interval of two days from April 5 to April 17. Hardness was decreased until 7th days and it was changed to increase at 9th days. Treatment of 60% maturity, $0^{\circ}C$ precooling and no light illumination of strawberry were shown the highest value in freshness. The soluble solid content harvested in 80% maturity strawberry was higher than 60% maturity strawberry until the third day. Quality grade decreased rapidly in 80% maturity stage with light illumination strawberry in comparison to the 60% maturity stage of strawberry. Hunter value 'L' and 'a' showed a rapid change in 60% maturity stage of strawberry. Weight loss decreased rapidly in 80% maturity, $0^{\circ}C$ precooling, and no light illumination of strawberry treatments. Gray mold incidence was found the most at 60% maturity, $4^{\circ}C$ precooling, and light illumination of strawberry. The results from our study indicate that effectiveness for keeping the freshness of strawberry was best achieved by harvesting in low maturity, precooling at $0^{\circ}C$, and with no light illumination.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.3
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• pp.196-201
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• 2011

Emission from meat cooking may contribute to the concentration of the Particulate Matters(PM) in the city. This study is to investigate the particle size and the emission characteristics of particulate matters from pork and beef cooking. The chamber was installed for sampling of PM generated from pork belly and beef sirloin cooking including seasoned ones. Cascade Impactor and Portable Aerosol Monitor (PAM) were used to analyse the particle size distribution. At the result of the Cascade Impactor sampling, particulate matters from the pork cooking was higher than that of beef. The gravimetric concentration of PM according to the size was highest at the range of $1.95{\sim}3.2{\mu}m$ and the gravimetric concentration of PM from the non-seasoned meat was higher than that of the seasoned one. The emission factors from pork, pork seasoned, beef and beef seasoned were 1.36 g/kg, 1.03 g/kg, 1.23 g/kg, 0.92 g/kg respectively. To see the result of PAM sampling, the ranges of $1.6{\sim}2.5{\mu}m$ and $2.5{\sim}3.5{\mu}m$ were reveled as highest. The ration of $PM_{2.5}/PM_{10}$ from pork and beef was 0.56~0.58. The emission factors from pork, pork seasoned, beef and beef seasoned measured by PAM were revealed as 3.37 g/kg, 2.76 g/kg, 2.93 g/kg, 2.77 g/kg respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5877-5884
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• 2014

Recently, abnormally cold weather has been reported more frequently in winter due to the climate change and abnormal weather changes. On the other hand, the heating capacity of a railcar may be not enough to warm the cabin under severe cold climatic conditions, which is one of the reasons for the passengers' complaints about heating. In this study, the effects of ambient temperature and heater power on the cabin temperature was investigated to obtain the minimum ambient temperature for the tested railcar. The test railcar was placed in a large-climatic chamber, and various ambient temperature conditions were simulated. The effects of the heater output were investigated by monitoring the cabin temperature under a range of heater output conditions. The mean cabin temperature was $14.0^{\circ}C$, which was far lower than the required minimum temperature of $18^{\circ}C$, under a $-10^{\circ}C$ ambient temperature condition with the maximum heat power. When the ambient temperature was set to $0^{\circ}C$ and $10^{\circ}C$, the maximum achievable cabin temperature was $26.1^{\circ}C$ and $34.0^{\circ}C$. Through calculations using the interpolation method, the minimum ambient temperature to maintain an $18^{\circ}C$ cabin temperature was $-6.7^{\circ}C$ for this car. The vertical temperature difference was higher with a higher power output and higher ambient temperature. The maximum vertical temperature difference was higher than $10^{\circ}C$ in some cases. However, the horizontal temperature difference vs. low temperature (< $2^{\circ}C$) was independent of the power output and ambient temperature. As a result, it is very important to reduce the vertical temperature difference to achieve good heating performance.

• Horticultural Science & Technology
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• v.31 no.2
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• pp.186-193
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• 2013

Potential of consumer unit packaging was investigated for quality maintenance during export simulation in king oyster mushrooms (Pleurotus eryngii). Mushrooms were harvested in late May, precooled to $4^{\circ}C$ within 6 hours, and then packaged for shipping in two ways: 2 kg bulk packaging in a polyethylene (PE) bag or three types of unit packaging methods such as 400 g in polypropylene film bag (PPB), 200 g on styrofoam tray + PE shrinkage film wrapping (STW), and 200 g in polyethylene terephthalate (PET) containers (PETC). For local distribution of bulk-packaged commodity, mushrooms were sorted again and packaged into 3 consumer units in the same way as for the initial shipping packages. Simulation of refrigerated container shipping was performed in a walk-in type pilot storage at $0.5^{\circ}C$ for 5 weeks, while local marketing simulation was carried out on the shelf at $7^{\circ}C$ for 7 days. During the shipment simulation, creation of modified atmosphere (MA) was substantial in 2 kg bulk packages with low $O_2$ below 2% and high $CO_2$ over 15% whereas, in PPB and PETC unit packages, relatively higher $O_2$ concentrations were observed. On the shelf at $7^{\circ}C$, $CO_2$ concentrations rapidly increased in PPB and PETC packages despite the short marketing period. Overall marketability evaluated by off-flavor, browning, and texture rating was maintained at excellent level when 2 kg bulk packaging in PE or unit packaging in PPB and PETC were used for shipment. In contrast, establishment of MA was very slight in STW packages during shipment and local distribution resulting in poor quality after export simulation. The results suggested that shipment using adequate consumer unit packaging is more practical and economically beneficial than using bulk packaging in the export program consisting of 5-week shipment and 7-day local distribution.

• Journal of Animal Environmental Science
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• v.17 no.2
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• pp.81-92
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• 2011

When we bury the infected poultry into the ground, we have many problems such as the difficulty of making sufficient area for burying, environmental contamination by the leachate, unpleasant ordor. Also, in case of burning the carcass of the infected poultry, there are some problems such as high cost, dust, unpleasant odor, etc. It could cause environmental contamination which many peoples and environmental organization complains about. In this study, we develop a treating system which treats the infected poultry carcass in a environmental method preventing the environment contamination. This system is composed of many processes. The euthanasia system uses rigid vinyl to trap and to do a euthanasia the infected poultry with lethal gas, carbon dioxide. And then, with the tractor attached grappler infected poultry carcass could be put into the carcass treating system. The euthanasia system uses rigid vinyl to trap the infected birds and to confine lethal gas, carbon dioxide. Infected poultry carcass are moved to carcass disposal system by collecting device which is attached at tractor. The carcass treatment system (capacity of disposal : 6.3 $m^3$) is installed on a truck and do one pass work, which is input, crush, stir, sterilize, and discharge treated carcass. 1,000 chickens was killed within 9.7min by $CO_2$ (300L/min) in the tent (10 $m^3$). The collecting device could carry 142 chickens at a time, and the movable carcass treatment system could sterilize 2 tons carcass per hour (at one time). This treatment systems was eco-friendly because it reduced the volume of carcass by 31.9% with no wastewater generation.

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.141-152
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• 2020

The rapid on-site measurement of hydroponic nutrients allows for the more efficient use of crop fertilizers. This paper reports on the development of an embedded on-site system consisting of multiple ion-selective electrodes (ISEs) for the real-time measurement of the concentrations of macronutrients in hydroponic solutions. The system included a combination of PVC ISEs for the detection of NO₃, K, and Ca ions, a cobalt-electrode for the detection of H₂PO₄, a double-junction reference electrode, a solution container, and a sampling system consisting of pumps and valves. An Arduino Due board was used to collect data and to control the volume of the sample. Prior to the measurement of each sample, a two-point normalization method was employed to adjust the sensitivity followed by an offset to minimize potential drift that might occur during continuous measurement. The predictive capabilities of the NO₃ and K ISEs based on PVC membranes were satisfactory, producing results that were in close agreement with the results of standard analyzers (R² = 0.99). Though the Ca ISE fabricated with Ca ionophore II underestimated the Ca concentration by an average of 55%, the strong linear relationship (R² > 0.84) makes it possible for the embedded system to be used in hydroponic NO₃, K, and Ca sensing. The cobalt-rod-based phosphate electrodes exhibited a relatively high error of 24.7±9.26% in the phosphate concentration range of 45 to 155 mg/L compared to standard methods due to inconsistent signal readings between replicates, illustrating the need for further research on the signal conditioning of cobalt electrodes to improve their predictive ability in hydroponic P sensing.

• Journal of Korea Water Resources Association
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• v.52 no.11
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• pp.917-929
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• 2019

Denitrification in streams is of great importance because it is essential for amelioration of water quality and accurate estimation of $N_2O$ budgets. Denitrification is a major biological source or sink of $N_2O$, an important greenhouse gas, which is a multi-step respiratory process that converts nitrate ($NO_3{^-}$) to gaseous forms of nitrogen ($N_2$ or $N_2O$). In aquatic ecosystems, the complex interactions of water flooding condition, substrate supply, hydrodynamic and biogeochemical properties modulate the extent of multi-step reactions required for $N_2O$ flux. Although water flow in streambed and residence time affect reaction output, effects of a complex interaction of hydrodynamic, geomorphology and biogeochemical controls on the magnitude of denitrification in streams are still illusive. In this work, we built a two-dimensional water flow channel and measured $N_2O$ flux from channel sediment with different bed geomorphology by using static closed chambers. Two independent experiments were conducted with identical flume and geomorphology but sediment with differences in dissolved organic carbon (DOC). The experiment flume was a circulation channel through which the effluent flows back, and the size of it was $37m{\times}1.2m{\times}1m$. Five days before the experiment began, urea fertilizer (46% N) was added to sediment with the rate of $0.5kg\;N/m^2$. A sand dune (1 m length and 0.15 m height) was made at the middle of channel to simulate variations in microtopography. In high- DOC experiment, $N_2O$ flux increases in the direction of flow, while the highest flux ($14.6{\pm}8.40{\mu}g\;N_2O-N/m^2\;hr$) was measured in the slope on the back side of the sand dune. followed by decreases afterward. In contrast, low DOC sediment did not show the geomorphological variations. We found that even though topographic variation influenced $N_2O$ flux and chemical properties, this effect is highly constrained by carbon availability.