• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.647-650
• /
• 2017

As the necessity of development of supersonic vehicle increases, securing an aerodynamic data from low to high altitude is requested for flying vehicles crusing in various high-tech environment. Therefore our research team built equipment by improving heating device of Model Aerodynamic Facility(MAF) of Konkuk University to simualte a real gas environment. Guided weapon system and temperature and velocity distribution according to the flow that is produced from the pier of supersonic vehicle is planned to be researched by using this equipment.

• Journal of the Korean Society of Combustion
• /
• v.17 no.4
• /
• pp.5-10
• /
• 2012

The reformer system is a chemical device that drives the conversion of hydrocarbon to hydrogen rich gas under high temperature environment($600-1,000^{\circ}C$). Generally, NG(Natural Gas) or AOG(Anode Off Gas) is used as fuel of fuel cell reformer combustion system. The experimental study to analyze the combustion characteristics of a premixed ceramic burner used for 0.5-1.0 kW fuel cell reformer was performed. Ceramic burner experiments using NG and AOG were carried out to investigate the flame stability characteristics by heating capacity, equivalence ratio and different fuels respectively. The results show that surface flames can be classified into green, red, blue and lift-off flames as the equivalence ratio of methane-air mixture decreases. And the stable flames can be established using NG and AOG as reformer fuel in the perforated ceramic burner. In particular, the blue flame is found to be stable at a lean equivalence ratio under different mixture conditions of NG and AOG for the 0.5 to 1.0 kW fuel cell system power range. NOx emission is under 60 ppm between 0.70 to 0.78 of equivalence ratio and CO emission is under 50 ppm between 0.70 to 0.84 of equivalence ratio.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.4
• /
• pp.271-275
• /
• 2020

Smart windows are used as windows and doors to determine the cooling and heating efficiency of a building. They have characteristics that can increase the energy efficiency of a building, which leads to energy savings. In addition, smart windows can control the amount of light transmitted from the external environment of a building to the interior of a building according to the needs of the user. In this study, a 297×210 ㎟ liquid crystal cell capable of controlling light transmittance was fabricated using a liquid crystal device as an optical shutter. The effect of driving voltage on the transmittance and the effect of the thermal environment on the driving stability were analyzed. We confirmed the applicability of using smart windows as exterior building materials.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.1059-1063
• /
• 2005

Development of a feed drive-system with high speed, positioning accuracy and thrust has been an important issue in modern automation systems and machine tools. Linear motors can be used as an efficient system to achieve such technical demands. By eliminating mechanical transmission mechanisms such as ball screw or rack-pinion, much higher speeds and greater acceleration can be achieved without backlash or excessive friction. However, due to great power loss and magnetic attraction of the linear motors heating and deflection problems occur. Therefore, it is necessary to design strong structure, cooling device with high efficiency and light weight construction in designing stage of linear motors. This paper presents an investigation into a structural design of linear motor system. In this research, a new concept of moving table with high stiffness and of cooling plate is also introduced. Structure analyses are performed by using a commercial code ANSYS in order to evaluate the design safety.

• International Journal of Railway
• /
• v.8 no.1
• /
• pp.10-14
• /
• 2015

Due to the characteristics of the vehicle structure, the magnetic levitation train has a confined bottom space thus a study on miniaturization and weight reduction of auxiliary power unit is essential. This auxiliary power unit is an essential device used for illumination, air conditioning, heating and air brake equipment excluding the motor. The previous auxiliary power unit for magnetic levitation train has used the hard switching having a high switching frequency with heavy loss in order to reduce the size of filter reactor and transformer but the reduction in volume was not significant. In this paper, by reducing the loss, reducing the size of the cooling unit and by increasing the switching frequency using the soft switching of resonant converter, it has miniaturized and reduced the weight of filter reactor and transformer which occupy significant space in the auxiliary power unit. This study has verified the performance of 50KVA grade prototype through simulated interpretation and analysis, and compared the size and weight of auxiliary power unit of the previous magnetic levitation train.

• Current Optics and Photonics
• /
• v.4 no.4
• /
• pp.273-276
• /
• 2020

We report on the relationship between output current for quadrant photodetector (QPD) and bias voltage in silicon-based p-i-n (positive-intrinsic-negative) QPD examined using millisecond pulse laser (ms pulse laser) irradiation. The mechanism governing the relationship was further studied experimentally. The output current curves were obtained by carrying out QPD under different bias voltages (0-40 V) irradiated by ms pulse laser. Compared to other photodetectors, the relaxation was created in the output current for QPD which is never present in other photodetectors, such as PIN and avalanche photodetector (APD), and the maximum value of relaxation was from 6.8 to 38.0 ㎂, the amplitude of relaxation increases with bias value. The mechanism behind this relaxation phenomenon can be ascribed to the bias voltage induced Joule heating effect. With bias voltage increasing, the temperature in a QPD device will increase accordingly, which makes carriers in a QPD move more dramatically, and thus leads to the formation of such relaxation.

• Journal of the Korean Society of Visualization
• /
• v.19 no.1
• /
• pp.62-67
• /
• 2021

Selective catalytic reduction(SCR) is an exhaust gas reduction device to remove nitro oxides (NOx). SCR operation of ship can be controlled through valves for minimizing economic loss from SCR. Valve in SCR-high pressure (HP) system is directly connected to engine exhaust and operates in high temperature and high pressure. Long-term thermal deformation induced by engine heat weakens the sealing of the valve, which can lead to unexpected failures during ship sailing. In order to prevent the unexpected failures due to long-term valve thermal deformation, a failure prediction system using autoregressive integrated moving average (ARIMA) was proposed. Based on the heating experiment, virtual data mimicking temperature range around the SCR-HP valve were produced. By detecting abnormal temperature rise and fall based on the short-term ARIMA prediction, an algorithm determines whether present temperature data is required for failure prediction. The signal processed by the data collection algorithm was interpolated for the failure prediction. By comparing mean average error (MAE) and root mean square error (RMSE), ARIMA model and suitable prediction instant were determined.

• Journal of the Korean Society for Heat Treatment
• /
• v.36 no.2
• /
• pp.86-95
• /
• 2023

This paper explained the equipment and process development to secure the source technology of controlled nitrification technology. The nitriding potential in the furnace was controlled only by adjusting the flow rate of ammonia gas introduced into the furnace. In addition, a control system was introduced to automate the nitriding process. The equipment's hardware was designed to enable controlled nitriding based on the conventional gas nitriding furnace, and an automation device was attached. As a result of measuring the temperature and quality uniformity for the equipment, the temperature and compound uniformity were ±1.2℃ and 14.3 ± 0.2 ㎛, respectively. And, it was confirmed that nitriding potential was controlled within the tolerance range of AMS2759-10B standard. In addition to parts for controlled nitriding, it was applied to products produced in existing conventional nitriding furnaces, and as a result, gas consumption was reduced by up to 80%.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.125-126
• /
• 2023

Recently, heat island and dry island phenomena occur frequently due to land surface development and excessive energy consumption in urban areas. As a result, the surface temperature of the building and the entire temperature of its surroundings are increased, and as a result, the durability of the building is rapidly deteriorated. In order to suppress these causes, a method of maintaining the temperature of road heating wires was implemented as a temporary measure, but this did not predict climate change. Therefore, this study is a method to measure the compressive strength, density, and thermal conductivity of lightweight concrete using waste glass foam beads. After fabricating a simple chamber, the temperature and humidity of the inside and outside were measured with an Arduino device in consideration of external factors. Therefore, if waste glass foam beads made through proper mixing are constructed in the urban center, the quality of the urban can be improved.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.11a
• /
• pp.51-52
• /
• 2023

Recently, heat island and dry island phenomena occur frequently due to land surface development and excessive energy consumption in urban areas. As a result, the surface temperature of the building and the entire temperature of its surroundings are increased, and as a result, the durability of the building is rapidly deteriorated. In order to suppress these causes, a method of maintaining the temperature of road heating wires was implemented as a temporary measure, but this did not predict climate change. Therefore, this study is a method to measure the compressive strength, density, and thermal conductivity of light weight concrete using waste glass foam beads. After fabricating a simple chamber, the temperature and humidity of the inside and outside were measured with an Arduino device in consideration of external factors. Therefore, if waste glass foam beads made through proper mixing are constructed in the urban center, the quality of the urban can be improved.