• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.845-855
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• 2022

The purpose of this study is to develop a self-propelled underground crop harvester and its performance was evaluated by measuring the load during actual potato harvesting operations. This study was conducted at a constant working speed of 1 km·h^-1. A load measurement system was installed to measure the actual load and the required working power was analyzed. A hydraulic pressure sensor was also installed to measure the hydraulic pressure. The required hydraulic power was calculated using the hydraulic pressure and flow rate. The results showed that the engine speed, torque, and power during harvesting operation were in the range of 845 - 1,423 rpm, 95 - 228 Nm, and 9 - 31 kW, respectively. Traction power, excluding the hydraulic pump of the tractor and power take-off (PTO) output, was in the range of 9 - 28 kW, and it was confirmed that it occupies a ratio of 16.2 to 50% of the engine rated output. The engine can supply the minimum required traction power to move the vehicle. This means that the engine used in this study could be down-sized to be suitable for an underground crop harvester. In this study, the gear stages of the tractor were not considered. This research thus shows the possibility of developing a self-propelled underground crop harvester.

• Nuclear Engineering and Technology
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• v.15 no.3
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• pp.179-187
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• 1983

The pH of containment spray and sump water following a LOCA for KNU 5'||'&'||'6 and KNU 1 was calculated to see if pH design criteria of containment spray system established by USNRC were met. The pH calculations have been made for the two cases; maximum pH and minimum pH. For KNU 5'||'&'||'6, results showed that long term sump pH values calculated for the maximum pH and minimum pH case well met the pH requirement of at least 8.5 and spray pH for the maximum case slightly exceeded the range of design criteria (8.5 to 11.0). For KNU 1, pH requirement of long term sump pH was also met, however, spray pH value for the maximum pH case was very largely greater than that of current pH requirement. (No pH requirement of containment spray water has been established at the time of designing KNU 1) In order to find the design parameters of containment spray system which are expected to meet the spray pH requirement, several calculations were wade, by changing the input parameters to "LCCAPH". Finally, it was shown that the boric acid concentration in RWST (refueling water storage tank), which was the primary sources of containment spray water during injection mode, be maintained the range of 2750 ppm to 2850 ppm, or tile flow rate of NaOH added to spray water he kept between 10 gpm to 24 gpm.

• Korean Journal of Food Science and Technology
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• v.19 no.3
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• pp.220-224
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• 1987

The concentration ranges forming surface excess of bovine serum albumin(BSA) and ovalbumin solutions were determined, and the factors affecting the foam separation of BSA were investigated. The surface tension of BSA solution decreased from 72 to 61 dynelcm, when the concentration changed from $5{\times}10^{-3}$ to $3{\times}10^{-2}%$, and the critical micelle concentration was appeared to be at 0.03% of BSA. At the isoelectric point (pH 4.9) of BSA, the foamate volume was maximum, but enrichment ratio was minimum, resulting in the maximum recovery rate. When the pH deviated from the isoelectric point, the foamate volume decreased and the enrichment ratio increased. The enrichment ratio increased, while the foamate volume decreased drastically as the temperature was elevated above $20^{\circ}C$, resulting in the decrease in recovery rate. As the gas flow rate increased, the enrichment ratio decreased and the foamate volume increased. When $(NH_4)_2SO_4$ was added, the enrichment ratio decreased, but the maximum foamate was obtained at ionic strength 7. The concentration to form the surface excess of ovlbumin, which has lower surface hydrophobicity than BSA, was 200 times higher than that of BSA. This fact indicates the possibility of selective foam separation by hydrophobicity difference of proteins.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.1
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• pp.56-61
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• 1999

Oxygen consumption rate of Far eastern catfish, Silurus asotus, weighing 280g, was measured using continuous flow respirometry chamber linked computer monitoring system. Mean oxygen consumption rates at $15^{\circ}C,\;20^{\circ}C,\;25^{\circ}C$, and $30^{\circ}C$ were ranged in 35.2$\~96.4mg\;O_2/kg$ fish/hr, 78.6$\~127.9mg\;O_2/kg$ fish/hr, 120.1$\~231.7mg\;O_2/kg$ fish/hr, and 197.5$\~352.3mg\;O_2/kg$ fish/hr, respectively. The oxygen consumption rates increased with increasing water temperature (p<0.05). A photoperiod-mediated oxygen consumption rates was higher during the light period than during the darkness (P<0.05). When acclimated with different photoperiods, 24L:0D, 12L:12D, and 0L:24D, the lowest oxygen consumption rate was observed in the continuous darkness (0L:24D). The differences between maximum and minimum oxygen consumption rates oyer 24 hour increased with increasing water temperature and the difference was the highest in 12L:12D. Oxygen consumption rate changed suddenly at dawn and at dusk.

• Journal of Bio-Environment Control
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• v.28 no.3
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• pp.225-233
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• 2019

In the summer season, natural ventilation is commonly used to reduce the inside air temperature of greenhouse when it rises above the optimal level. The greenhouse shape, vent design, and position play a critical role in the effectiveness of natural ventilation. In this study, computational fluid dynamics (CFD) was employed to investigate the effect of different roof vent designs along with side vents on the buoyancy-driven natural ventilation. The boussinesq hypothesis was used to simulate the buoyancy effect to the whole computational domain. RNG K-epsilon turbulence model was utilized, and a discrete originates (DO) radiation model was used with solar ray tracing to simulate the effect of solar radiation. The CFD model was validated using the experimentally obtained greenhouse internal temperature, and the experimental and computed results agreed well. Furthermore, this model was adopted to compare the internal greenhouse air temperature and ventilation rate for seven different roof vent designs. The results revealed that the inside-to-outside air temperature differences of the greenhouse varied from 3.2 to $9.6^{\circ}C$ depending on the different studied roof vent types. Moreover, the ventilation rate was within the range from 0.33 to $0.49min^{-1}$. Our findings show that the conical type roof ventilation has minimum inside-to-outside air temperature difference of $3.2^{\circ}C$ and a maximum ventilation rate of $0.49min^{-1}$.

• Science of Emotion and Sensibility
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• v.22 no.1
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• pp.89-100
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• 2019

Sleep apnea, a medical condition associated with a variety of complications, is generally monitored by standard sleep polysomnography, which is expensive and uncomfortable. To overcome these limitations, this study proposes an unconstrained wearable monitoring system with stretch-fiber sensors that integrate with the wearer's clothing. The system allows patients to undergo examinations in a familiar environment while minimizing the occurrence of skin allergies caused by adhesive tools. As smart clothing for adult males with sleep apnea, long-sleeved T-shirts embedding fibrous sensors were developed, enabling real-time monitoring of the patients' breathing rate, oxygen saturation, and airflow as sleep apnea diagnostic indicators. The gauge factor was measured as 20.3 in sample 4. The maximum breathing intake, measured during three large breaths, was 2048 ml. the oxygen saturation was measured before and during breath-holding. The oxygen saturation change was 69.45%, showing a minimum measurable oxygen saturation of 70%. After washing the garment, the gauge factor reduced only to 18.0, confirming the durability of the proposed system. The wearable sleep apnea monitoring smart clothes are readily available in the home and can measure three indicators of sleep apnea: respiration rate, breathing flow and oxygen saturation.

• The korean journal of orthodontics
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• v.40 no.2
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• pp.66-76
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• 2010

Objective: Obstructive sleep apnea (OSA) is a common disorder which is characterized by a recurrence of entire or partial collapse of the pharyngeal airway during sleep. A given tidal volume must traverse the soft tissue tube structure of the upper airway, so the tendency for airway obstruction is influenced by the geometries of the duct and characteristics of the airflow in respect to fluid dynamics. Methods: Individualized 3D FEA models were reconstructed from pretreatment computerized tomogram images of three patients with obstructive sleep apnea. 3D computational fluid dynamics analysis was used to observe the effect of airway geometry on the flow velocity, negative pressure and pressure drop in the upper airway at an inspiration flow rate of 170, 200, and 230 ml/s per nostril. Results: In all 3 models, large airflow velocity and negative pressure were observed around the section of minimum area (SMA), the region which narrows around the velopharynx and oropharynx. The bigger the Out-A (outlet area)/ SMA-A (SMA area) ratio, the greater was the change in airflow velocity and negative pressure. Conclusions: Pressure drop meaning the difference between highest pressure at nostril and lowest pressure at SMA, is a good indicator for upper airway resistance which increased more as the airflow volume was increased.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.79-87
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• 2010

Field water qualities (temperature, pH, Eh, EC, DO) was monitored by 6 times March to September 2009 on background water (BW) and acid mine drainage (AMD0, AMD1, AMD2 and AMD3 points), and flow rate was measured on AMD0 point. Acid mine drainage flowed out from abandoned Ilgwang mine were high acid waters that lower than pH 3, and Eh component was ranged 400 to 600 mV. EC measured on acid mine drainage were higher over 10 times than background water, DO component was increased by reaction on the air during the water flow from AMD0 point to AMD4 point. Heavy metal concentrations in acid mine drainage were ordered Fe > Cu > Zn > Mn > As > Cd, and Fe concentration was highest for 81.870~474.30 mg/L. Monitoring periods measured maximum concentrations of heavy metals were May for As and Cd, June for Fe, July for Cu, Zn and Mn. The periods measured minimum concentrations were monitored April for Cd and Mn, September for Fe, Cu, Zn and As. Discharge mass of heavy metal components were calculated 53.44 kg for Fe, 6.25 kg for Cu, 5.26 kg for Zn, 2.13 kg for Mn, 0.14 kg for As and 0.04 kg for Cd, respectively. Total discharge mass of heavy metal components were calculated 67.26 kg for 1 day, and Fe component was taken 79% of total mass.

• Journal of Korean Society of Transportation
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• v.36 no.2
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• pp.67-85
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• 2018

Vehicle platooning through wireless communication and automated driving technology has become realized. Platooning is a technique in which several vehicles travel at regular intervals while maintaining a minimum safety distance. Truck platooning is of keen interest because it contributes to preventing truck crashes and reducing vehicle emissions, in addition to the increase in truck flow capacity. However, it should be noted that interactions between vehicle platoons and adjacent manually-driven vehicles (MV) significantly give an impact on the performance of traffic flow. In particular, when vehicles entering from on-ramp attempt to merge into the mainstream of freeway, proper interactions by adjusting platoon size and inter-platoon spacing are required to maximize traffic performance. This study developed a methodology for establishing operational strategies for truck platoonings on freeway on-ramp areas. Average speed and conflict rate were used as measure of effectiveness (MOE) to evaluate operational efficiency and safety. Microscopic traffic simulation experiments using VISSIM were conducted to evaluate the effectiveness of various platooning scenarios. A decision making process for selecting better platoon operations to satisfy operations and safety requirements was proposed. It was revealed that a platoon operating scenario with 50m inter-platoon spacing and the platoon consisting of 6 vehicles outperformed other scenarios. The proposed methodology would effectively support the realization of novel traffic management concepts in the era of automated driving environments.

• Nuclear Engineering and Technology
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• v.14 no.4
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• pp.186-195
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• 1982

The steam line break accident for Kori Unit 1 is analyzed by a code SYSRAN which calculates nuclear power and heat flux using the point kinetics equation and the lumped-parameter model and calculates system transient using the mass and energy balance equation with the assumption of uniform reactor coolant system pressure. The 1.4 f $t^2$ steam line break accident is analyzed at EOL (End of Life), hot shutdown condition in which case the accident would be most severe. The steam discharge rate is assumed to follow the Moody critical flow model. The results reveal the peak heat flux of 38% of nominal full power value at 60 second after the accident initiates, which is higher than the FSAR result of 26%. Trends for the transient are in good agreement with FSAR results. A sensitivity study shows that this accident is most sensitive to the moderator density coefficient and the lower plenum mixing factor. The DNBR calculation under the assumption of $F_{{\Delta}H}$=3.66, which is used in the FSAR with all the control and the shutdown assemblies inserted except one B bank assembly and of Fz=1.55 shows that minimum DNBR reaches 1.62 at 60 second, indicating that the fuel failure is not anticipated to occur. The point kinetics equation, the lumped-parameter model and the system transient model which uses the mass and energy balance equation are verified to be effective to follow the system transient phenomena of the nuclear power plants.lear power plants.