• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.527-539
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• 2018

The subway used by many passengers is required to maintain a safe and comfortable environment and PSD (Platform Screen Door) must be installed in the platform after reinforcing the standard in 2003. In the previous research, in case of subway fire to control it, it is necessary to design the optimal ventilation and smoke exhaust system according to equipment capacity of the smoke exhaust system. Therefore, in this study, based on the results of previous research, three-dimensional numerical analysis was performed for the CO gas and smoke flow by the subway ventilation system in case of platform fire. As a result of this study, it was found that in case of emergency, if only the upper-level smoke exhaust system is activated, the risk of evacuation is high due to CO gas (653.8 ppm) and smoke concentration ($768.4mg/m^3$). And when all the smoke exhaust systems are activated and only the fire side PSD is opened, CO gas (36.0 ppm) and smoke concentration ($26.2mg/m^3$) are detected and the propagation range of smoke flow was reduced. When all the smoke exhaust systems are activated and only the fire side PSD is closed, it was analyzed as the most effective ventilation mode in the evacuation environment due to the absence of smoke-recirculation.

• Journal of Biosystems Engineering
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• v.9 no.1
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• pp.22-33
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• 1984

Husk separator is an indispensable equipment in rice milling plants. However, any basic research on the designing and operating criteria of the husk separator have rarely been conducted in Korea. According to the survey results reported recently, grain loss occurs in the process of rice husk separation at custom rice milling plants in Korea and the performance of husk separator has also not been identified. With this regard this study was conducted with a typical commercial husk separator to investigate the effect of the operational factors such as feed rate, blower speed and opening ratio on the velocity distribution in the air duct and the performance of the separator. The results are summerized as follows: 1. The average wind velocity in the primary air duct increased linearly with the blower rpm and the size of air inlet port in both cases of double type and single type operations. 2. The coefficient of variation in the horizontal wind velocities in the primary air duct was the minimum when the opening ratio was 0.22 ($0.052m^2$ of air inlet port) in both cases of single type and double type operations regardless of the blower speeds used in this test. The average wind velocity at the upper part of air duct was greater by 2-5 m/s than the velocity at the bottom part in double type operation. In case of single type operation, however, the average velocity in the middle part was greater than the upper or bottom part when the opening ratio was greater than 0.74. 3. The relationship between the overall effectiveness of separation(Ed for double type and Es for single type) and the average wind velocity (Va) in the primary air duct was expressed in the following quadratic functions. $$Ed=-190.84+106.18Va-10.052Va^2$$ ($r^2$ = 0.97782) $$Es=-223.76+106.23Va-9.1935Va^2$$ ($r^2$ = 0.97029) The average wind velocity required to obtain the overall effectiveness of separation more than 80% ranged from 4.04 m/sec to 5.84 m/sec in case of double type operation, and from 4.70 m/sec to 6.20 m/sec in case of single type. 4. An optimum wind velocity can be obtained with an increase in the blower speed or the size of air inlet port as presented in Figure 8. There was a tendency that the faster the blower speed, the narrower the control range of the air inlet port. 5. The feed rates (1850kg/hr and 2100kg/hr) adopted in this experiment did not bring about a significant difference in both the overall effectiveness of separation and the power consumption. 6. The energy consumption increased cubically with the blower speed but linearly with the size of the air inlet port. On the basis of the results described in items 1, 3, and 6, it would be more economic to adjust the size of the air inlet port larger with a relatively low blower speed than to adjust the size smaller with a relatively high speed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.681-688
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• 2018

As environmental regulations have been strengthened and high fuel efficiency has been in demand in recent years, the number of ships using natural gas as a fuel is increasing. The demand for ships using LPG or methanol, which are emerging as eco-friendly vessel fuels, is also increasing. In this perspective, ME-LGI engines using LPG or methanol as a fuel have attracted considerable attention. Ships equipped with an ME-LGI engine are required to check the reliability of the fuel injection valve during shipping. This means that the development of a fuel injection valve tester is essential for the commercialization of ME-LGI engine. This study conducted the conceptual design of a fuel injection valve tester for ME-LGI engines using a system engineering process in the order of requirements analysis, functional analysis, and design synthesis. In the requirement analysis stage, the operating process of fuel injection valve was analyzed, and the necessity of checking the sealing oil leakage was then derived. In the functional analysis stage, the functions and flow of them were defined at each functional level. In the design synthesis stage, the equipment for each function was set and the process block diagram based on it was derived. In addition, preliminary risk analysis was performed as a part of system analysis and control, and safety measures were added to the conceptual design. This study is expected to be a good reference material for the concept design of other systems in the future because it shows the application process of a system engineering process to the conceptual design in detail.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.9-15
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• 2018

The turbochargers, which are used widely in diesel and gasoline engines, are an effective device to reduce fuel consumption and emissions. On the other hand, turbo-lag is one of the main problems of a turbocharger. Bearing friction losses is a major cause of turbo lag and is particularly intense in the lower speed range of the engine. Current turbochargers are mostly equipped with floating bearings: two journal bearings and one thrust bearing. This study focused on the bearing friction at the lower speed range and the experimental equipment was established with a drive-motor, load-cell, magnetic coupling, and oil control system. Finally, the friction losses of turbochargers were measured considering the influence of the rotating speed from 30,000rpm to 90,000rpm, oil temperature from $50^{\circ}C$ to $100^{\circ}C$, and oil supply pressure of 3bar and 4bar. The friction power losses were increased exponentially to 1.6 when the turbocharger speed was increased. Friction torques decreased with increasing oil temperature and increased with increasing oil pressure. Therefore, the oil temperature and pressure must be maintained at appropriate levels.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.294-301
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• 2017

In this study, we found the optimal manufacturing conditions of livestock manure sludge RDF with the oil-drying method. We performed oil evaporation, oil drying and pelletizing of the sludge to evaluate the value of the product (sludge RDF), and measured the performance of the product using calorimeter and PXRF equipment. Also, we conducted the calorie comparison test between sludge RDF manufactured in this study and wood RDF generally used in the field. Experimental results showed that 30g of the sludge treated by vegetable oil at $130^{\circ}C$ for 25 minutes were the optimal conditions to make the sludge RDF (considering the aspects of eco-friendly and mass production). The caloric value of the sludge RDF manufactured in this study was 5211kcal/kg which is higher than that of wood RDF used widely in the market. Finally, PXRF results showed sludge RDF contains no heavy metals with the exception of sulfur. Therefore, we recommend more study about the sulfur control process for future development of the industrial manufacturing process.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.6
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• pp.553-560
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• 2014

The road tunnel install a vent for the purpose of ventilation and smoke control. Ventilation equipment capacity(number of jet fans) depends on from the condition that of the pressure and ventilation resistance. Pressure and the resistance under operating vehicle have affected on the drag coefficient. The drag coefficient of the tunnel have affected by the blockage effect and slipstream effects. However, when calculating the ventilation fan, are not properly consider taking into account such effects. Therefore, ventilation force may have been slightly overestimated. This paper describes the drag coefficient through a numerical analysis to calculate the equivalent resistance area that reflects the vehicle distance, and examined the equivalent resistance area. The ventilation coefficient corresponding to the result heavy vehicle mixing ratio of the present study was not clear. Equivalent resistance area had reduced by about 86% compared to the road design handbook current standards. Also it had analyzed and reduced to 62.2% compared to Korea Highway Corporation ventilation design criteria ratio, which is the old standard.

• Journal of Microbiology and Biotechnology
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• v.28 no.11
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• pp.1928-1936
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• 2018

Recently, human infections caused by severe fever with thrombocytopenia syndrome virus (SFTSV), which can lead to fatality, have dramatically increased in East Asia. With the unavailability of vaccines or antiviral drugs to prevent and/or treat SFTSV infection, early rapid diagnosis is critical for prevention and control of the disease. Here, we report the development of a simple, rapid and sensitive portable detection method for SFTSV infection applying reverse transcription-loop mediated isothermal amplification (RT-LAMP) combined with one-pot colorimetric visualization and electro-free reaction platform. This method utilizes a pocket warmer to facilitate diagnosis in a resource-limited setting. Specific primers were designed to target the highly-conserved region of L gene of SFTSV. The detection limit of the RT-LAMP assay was approximately $10^0$ viral genome copies from three different SFTSV strains. This assay exhibited comparable sensitivity to qRT-PCR and 10-fold more sensitivity than conventional RT-PCR, with a rapid detection time of 30 to 60 minutes. The RT-LAMP assay using SFTSV clinical specimens has demonstrated a similar detection rate to qRT-PCR and a higher detection rate compared to conventional RT-PCR. Moreover, there was no observed cross-reactive amplification of other human infectious viruses including Japanese Encephalitis Virus (JEV), Dengue, Enterovirus, Zika, Influenza and Middle East Respiratory Syndrome Coronavirus (MERS-CoV). This highly sensitive, electro- and equipment-free rapid colorimetric visualization method is feasible for resource-limited SFTSV field diagnosis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.585-591
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• 2017

Turbocharging is widely used in diesel and gasoline engines as an effective way to reduce fuel consumption. But turbochargers have turbo-lag due to mechanical friction losses. Bearing friction losses are a major cause of mechanical friction losses and are particularly intensified in the lower speed range of the engine. Current turbochargers mostly use oil bearings (two journal bearings and one thrust bearing). In this study, we focus on the bearing friction in the lower speed range. Experimental equipment was made using a drive motor, load cell, magnetic coupling, and oil control system. We measured the friction losses of the turbocharger while considering the influence of the rotation speed, oil temperature, and pressure. The friction power losses increased exponentially when the turbocharger speed increased.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.64-68
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• 2007

This paper describes the development of RF front.end equipment of a wide band high precision satellite navigation receiver to be able to receive the currently available GPS navigation signal and the GALILEO navigation signal to be developed in Europe in the near future. The wide band satellite navigation receiver with high precision performance is composed of L - band antenna, RF/IF converters for multi - band navigation signals, and high performance baseband processor. The L - band satellite navigation antenna is able to be received the signals in the range from 1.1 GHz to 1.6 GHz and from the navigation satellite positioned near the horizon. The navigation signal of GALILEO navigation satellite consists of L1, E5, and E6 band with signal bandwidth more than 20 MHz which is wider than GPS signal. Due to the wide band navigation signal, the IF frequency and signal processing speed should be increased. The RF/IF converter has been designed with the single stage downconversion structure, and the IF frequency of 140 MHz has been derived from considering the maximum signal bandwidth and the sampling frequency of 112 MHz to be used in ADC circuit. The final output of RF/IF converter is a digital IF signal which is generated from signal processing of the AD converter from the IF signal. The developed RF front - end has the C/N0 performance over 40dB - Hz for the - 130dBm input signal power and includes the automatic gain control circuits to provide the dynamic range over 40dB.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.12
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• pp.2221-2231
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• 2017

In this paper, we surveyed previous cases, network protocols (such as Wi-Fi, Zigbee, Z-wave, and WirelessHart) and propagation characteristics on the application of maintaining equipments for instrumentation and control (I&C) using wireless communication techniques inside the nuclear power plant (NPP). In addition, we compared and analyzed the difference of detailed regulations with respect to the electromagnetic interference (EMI) and radio frequency interference (RFI) in the Regulatory Guide 1.180 rev. 1 (RG. 1.180) for adopting the wireless communication techniques inside the NPP, and other regulations, such as MIL-STD 461E and IEC 61000-4, that are recognized in the KINS/RG-N03.09 (Rev. 2). Furthermore, we investigated evaluating factors about electromagnetic properties by considering indoor environments, wave scattering, shielding effectiveness, and the indoor wave attenuation model that were not included in the current electromagnetic compatibility regulation.