• Journal of the Korean Institute of Gas
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• v.15 no.1
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• pp.40-45
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• 2011

During process operations, overpressure can be caused by operator's error or malfunction of the device. To prevent this overpressure, gas was released through blowdown system. Because most of released gases are the hydrocarbon mixture and have flammable and toxic properties, the gas is released after burning in flare stack. The increase of scale and complexity of plant requires higher or additional flare stacks. This study tried to solve this problem through flare gas recovery system.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1066-1074
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• 2015

This paper presents the reverse recovery characteristic according to the change of switching states when Si diode and SiC diode are used as clamp diode and proposes a method to minimize the switching loss containing the reverse recovery loss in the neutral-point-clamped inverter at low modulation index. The previous papers introduce many multiple circuits replacing Si diode with SiC diode to reduce the switching loss. In the neutral-point-clamped inverter, the switching loss can be also reduced by replacing device in the clamp diode. However, the switching loss in IGBT is large and the reduced switching loss cannot be still neglected. It is expected that the reverse recovery effect can be infrequent and the switching loss can be considerably reduced by the proposed method. Therefore, it is also possible to operate the inverter at the higher frequency with the better system efficiency and reduce the volume, weight and cost of filters and heatsink. The effectiveness of the proposed method is verified by numerical analysis and experiment results.

• Journal of Mechanical Science and Technology
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• v.20 no.11
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• pp.1961-1971
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• 2006

A soft recovery system (SRS) is a device that stops a high speed projectile without damaging the projectile. The SRS is necessary to verify the shock resistant requirements of microelectronics and electro-optic sensors in smart munitions, where the projectiles experience over 20,000 g acceleration inside the barrel. In this study, a computer code for the performance evaluation of a SRS based on ballistic compression decelerator concept has been developed. It consists of a time accurate compressible one-dimensional Euler code with use of deforming grid and a projectile motion analysis code. The Euler code employs Roe's approximate Riemann solver with a total variation diminishing (TVD) method. A fully implicit dual time stepping method is used to advance the solution in time. In addition, the geometric conservation law (GCL) is applied to predict the solutions accurately on the deforming mesh. The equation of motion for the projectile is solved with the four-stage Runge-Kutta time integration method. A small scale SRS to catch a 20 mm bullet fired at 500 m/s within 1,600 g-limit has been designed with the proposed method.

• Journal of Astronomy and Space Sciences
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• v.35 no.4
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• pp.243-252
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• 2018

In a satellite gravimetry mission similar to GRACE, the precision of inter-satellite ranging is one of the key factors affecting the quality of gravity field recovery. In this paper, the impact of ranging precision on the accuracy of recovered geopotential coefficients is analyzed. Simulated precise orbit determination (POD) data and inter-satellite range data of formation-flying satellites containing white noise were generated, and geopotential coefficients were recovered from these simulated data sets using the crude acceleration approach. The accuracy of the recovered coefficients was quantitatively compared between data sets encompassing different ranging precisions. From this analysis, a rough prediction of the accuracy of geopotential coefficients could be obtained from the hypothetical mission. For a given POD precision, a ranging measurement precision that matches the POD precision was determined. Since the purpose of adopting inter-satellite ranging in a gravimetry mission is to overcome the imprecision of determining orbits, ranging measurements should be more precise than POD. For that reason, it can be concluded that this critical ranging precision matching the POD precision can serve as the minimum precision requirement for an on-board ranging device. Although the result obtained herein is about a very particular case, this methodology can also be applied in cases where different parameters are used.

• Journal of Korea Multimedia Society
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• v.25 no.3
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• pp.461-467
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• 2022

This research is to raise awareness of food safety by designing and supporting a hazard food information notification platform for consumers. To this end, the design was carried out by dividing the process into a data extraction process, an application screen design process, and a CNN-based food inference process. Data was collected through public data APIs and crawling, and it was sent to each activity screen designed for Android studios so that it could be output. As a result, when the platform is executed, information on hazardous food names, registration dates, food classification, manufacturing dates, recovery grades, recovery reasons, recovery methods, company names, barcode numbers, and packaging units can be intuitively and conveniently checked. In addition, CNN-based food inference processes allowed mobile cameras to infer harmful food and applied various quantization techniques such as Dynamic Range, Integer, and Float16 to compare the degree of improvement in inference performance. As a result, the group that applied basic quantization and treated device resources with GPU showed the greatest improvement in inference performance. Through this platform, it is expected that the reliability of food safety will be improved by making it more convenient for consumers to recognize food risks.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.4
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• pp.350-361
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• 2014

Exhaust gas containing wood tar of high concentration is discharged from charcoal production kilns. The large amount of emissions are often found by operational failure. The purpose of this study is to investigate the performance of an integrated treatment system in treating charcoal production exhaust. The system, which combined a tar collection device and a post-combustion unit, was proposed to remove moisture, wood tar, particulate matter, and other gas-phase pollutants (CO, $CH_4$, total hydrogen carbons) from exhaust gases. Heat recovery units were also applied in the system to utilize waste heat.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.273-279
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• 2008

The purpose of this study is not only to evaluate thermal performance but also to find the stress behavior of heat transfer tubes under the part load operation in Heat Recovery Steam Generator. Flow analysis was performed to know the behavior of exhaust gas from gas turbine and thermal performance was calculated using distribution of hot exhaust velocity. In addition, tubes temperature during operation were gathered from actual plant to verify the uneven flow distribution under part load operation. Stress analysis was performed using tubes temperature data gathered from actual plant under both part and full load operations to know the stress behavior of tubes.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.149-152
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• 2003

Soruce/drain (or, LDD) formation technology is critical to device reliability especially in the case of short channel LTPS-TFT devices. Ion shower doping with a main ion source of $P_2H_x$ was conducted on ELA Poly-Si. We report the effects of annealing methods on dopant activation and damage recovery in ion-shower doped poly-Si.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.381-386
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• 2001

The dust generated from the electric arc furnace steel making process is classified as hazardous material by Korean Environmental Protection Acts, mainly because of the existence of water teachable Pb, Zn and Cd. Thus the treatment of EAF dust is being carried out to fulfill both the environmental aspect and recovery of valuable metals. To establish the proper process for recovering the valuable metals (Fe, Zn, Pb and Cd) and producing the non-toxic slag from EAF dust, using RAPID-10 system, feasibility study have been carried out. To find out the scale-up factor for designing the commercial scale EAF dust treatment process(capacity 50,000 ton EAF dust per year) entitled RAPID-50 system. The design and construction of RAPID-50 (RIST Arc Plasma Industrial Device) system for treating 50,000 ton of EAF dust per year is now undergoing. Overall plan for treating EAF dust generated in KOREA will be setup after successful operation (December, 2002) of RAPID-50 system.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.908-912
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• 2003

The waste heat recovery system using heat pipe was tested for the consideration of developing the high-efficiency waste heat recovery technology. Heat pipe, a effective device that can quickly transfer large amounts of heat energy using the phase change of the working fluid and the characteristics of Electric Heater Bars used for alternative heating system are introduced In this paper. In order to increase energy efficiency, the system which controls the status of electric heater bars and the temperature of heat pipe installed has developed.