• Journal of Korean Society of Water and Wastewater
• /
• v.22 no.6
• /
• pp.681-687
• /
• 2008

It is well known that the water infiltration rate depends on soil properties such as soil water content, water head, capillary suction, density, hydraulic conductivity, and porosity. However, most of proposed infiltration models assume that the air phase is continuous and in equilibrium with the atmosphere or air compression and air entrapment on infiltration was not considered. This study presents experimental results on unsaturated water infiltration to relate air entrapment and hydraulic conductivity function based on soil air properties. The objectives of this study were to measure change of soil air pressure ahead of wetting front under air drain and air confined condition to find the confined air effect on infiltration rate, to reduce the entrapped air volume related with soil air pressure to increase the soil permeability, and to make a basis of infiltration process model for the purpose of improvement of infiltration rate in the homogeneous soil column. The results of the work show that soil air pressure increases according to increasement of the saturated soil depth rather than the wetting front depth during infiltration process.

• IE interfaces
• /
• v.20 no.3
• /
• pp.298-308
• /
• 2007

Radio Frequency Identification (RFID) is one of Identification Technologies today. Many of the large retailers in the United States and Europe have established requirements for their suppliers to use RFID technology in 2004. Recently Airbus and Boeing have announced plans to develop a single RFID specification to be used by both companies to use RFID tags to identify commercial aircraft parts. However, it does not mean the end of barcode and it may take several years before the wide adoption of the RFID. This is because a precise business process reengineering is required with technology itself to get the potential benefits of RFID. In this paper, we introduce an RFID enabled air baggage handling process which has been developed and tested recently. We believe our study would give a good guideline for further researches on RFID application in the aviation industry.

• Journal of Environmental Health Sciences
• /
• v.39 no.3
• /
• pp.289-299
• /
• 2013

Objectives: For the field application of the dielectric barrier discharge plasma reactor, scale-up of the plasma reactor is needed. This study investigated the possibility of inactivation of microorganisms in sewage using pilot multi-plasma reactor. We also considered the possibility of degradation of total organic carbon (TOC) and nonbiodegradable matter ($UV_{254}$) in sewage. Methods: The pilot plasma reactor consists of plasma reactor with three plasma modules (discharge electrode and quartz dielectric tube), liquid-gas mixer, high voltage transformers, gas supply equipment and a liquid circulation system. In order to determine the operating conditions of the pilot plasma reactor, we performed experiments on the operation parameters such as gas and liquid flow rate and electric discharge voltage. Results: The experimental results showed that optimum operation conditions for the pilot plasma reactor in batch experiments were 1 L/min air flow rate), 4 L/min liquid circulation rate, and 13 kV electric discharge voltage, respectively. The main operation factor of the pilot plasma process was the high voltage. In continuous operation of the air plasma process, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal condition of 13 kV were $10^{2.24}$ CFU/mL, 56.5% and 8.6%, respectively, while in oxygen plasma process at 10 kV, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal conditions were $10^{1.0}$ CFU/mL, 73.3% and 24.4%, respectively. Electric power was increased exponentially with the increase in high voltage ($R^2$ = 0.9964). Electric power = $0.0492{\times}\exp^{(0.6027{\times}lectric\;discharge\;voltage)}$ Conclusions: Inactivation of microorganisms in sewage effluent using the pilot plasma process was done. The performance of oxygen plasma process was superior to air plasma process. The power consumption of oxygen plasma process was less than that of air plasma process. However, it was considered that the final evaluation of air and oxygen plasma must be evaluated by considering low power consumption, high process performance, operating costs and facility expenses of an oxygen generator.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.18 no.4
• /
• pp.12-21
• /
• 2022

Steam assisted gravity drainage(SAGD) is a process that drills well in the underground oil sands layer, injects hightemperature steam, lowers the viscosity of buried bitumen, and recovers it to the ground. Recently, direct contact steam generator(DCSG) is being developed to maximize steam efficiency for SAGD process. The DCSG requires high technology to achieve pressurized combustion and steam generation in accordance with underground pressurized conditions. Therefore, it is necessary to develop a combustion technology that can control the heat load and exhaust gas composition. In this study, process analysis of high-pressurized DCSG was conducted to apply oxygen enrichment technology in which nitrogen of the air was partially removed for increasing steam production and reducing fuel consumption. As the process analysis conditions, methane as the fuel and normal air or oxygen enriched air as the oxidizing agent were applied to high-pressurized DCSG process model. A simple combustion reaction program was used to calculate the property variations for combustion temperature, steam ratio and residual heat in exhaust gas. As a major results, the steam production efficiency of DCSG using the pure oxygen was about 6% higher than that of the normal air due to the reducing nitrogen in the air. The results of this study will be used as operating data to test the demonstration device.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.10a
• /
• pp.222-225
• /
• 2008

Due to new requirements of the automotive industry, concerning lightweight and non-corroding construction, new production methods, The Hot Air Forming process of aluminum alloys are of special interest. The disadvantage of aluminum alloy is the poorer formability compared to steel. The Hot Air Forming process is one of the forming process receiving recent attention. In the current study, Fabrication of aluminum rear subframe has been attempted using seam and seamless aluminum tubes. On the base of hot workability of the extruded tube and PAM-STAMP simulation results, Optimum condition for fabricating aluminum rear sub(lame parts by Hot Air Forming could be determined.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2001.02a
• /
• pp.132-135
• /
• 2001

Cryogenic air separation unit(ASU) was developed about 100 year ago in Europe. However, because there is not any ability of process design or manufacturing of ASU in Korea, many ASUs come from advanced countries every year. The purpose of this study is the development of cryogenic air separation unit by our own ability, especially cold box for nitrogen production. On this study, we developed the computer program for physical properties of gases and process simulation. We also did process design and manufactured of cold box, including air separation column, liquid air heat exchanger and condenser. The result of cold box test was successful.

• 연구논문집
• /
• s.31
• /
• pp.23-43
• /
• 2001

An experimental investigation on the reduction of nitrogen oxide emission from swirling, turbulent diffusion flames was conducted using multi air staged combustor, The combustor utilizes swirler to dampen fuel/air mixing, allowing an extended residence time for fuel pyrolysis and fuel-N conversion chemistry in an locally fuel-rich environment prior to burnout. This process also allow to reduce thermal NOx formation to lessen the temperature of reaction zone. The aerodynamic process therefore emulates the conventional staged combustion process, but without the need for the physically separate fuel-rich and -lean stages. Parametric studies on the ratios of each staged air and droplet size were carried out the feasibility of fuel/air mixing for low NOx combustion with diesel and pyridine mixed diesel fuel oil.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.579-580
• /
• 2013

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.25 no.3
• /
• pp.453-459
• /
• 1996

This study was carried out to determine the changes in quality during the drying process and the optimum drying condition for utilizing soybean curd residue. The quality criteria for soybean curd residue were acid value, peroxide value, fatty acid composition and microbial concentration. The acid values of soybean curd residue were 7.5, 4.5 and 5.9 KOH mg/g upon 12 hour drying with open-air sun, ambient-air blast and warm-air blast, respectively. The numbers of total aerobic bacteria and molds increased remarkably during drying with open-air sunlight, ambient-air blast and warm-air blast except for hot air blast. Among different drying methods, the hot air blast drying(1kg of sample) was the most effective methods, which completed in three hours. Also, the drying method demonstrated a typical drying curve ; settling down, constant rate drying and falling rate drying period were shown within one hour, from one and three hours and after three hours, respectively. Moreover, there was significant variation in the constant drying period for the quality of soybean curd residue.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.6
• /
• pp.35-40
• /
• 2017

The aerodynamic performance of airplane is different according to the configuration of landing gear. As the drag becomes different according to this configuration, the flow stream of air must be smooth at taking off and landing. In this study, the configuration of landing gear was designed each in order to enhance the energy efficiency of airplane. Five models were compared in total at analysis. The magnitudes of drag and pressure became different and the air pressure of wake were changed due to the configuration. So, the air pressure due to the flow velocity and the air resistance happening at the rear can be estimated according to the configuration of landing gear. It is thought to improve the performance of airplane through the result of this study.