• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7773-7780
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• 2015

Analysis of existing kettle and its heating system has been the topic for localization technology development. Test pieces are made, polished and etched for existing kettle analysis. Surface of test pieces is observed using SEM, the kettle is verified to be made by deep drawing process from Ferrite-Perlite material. The kettle is also identified to be plated $16{\sim}49{\mu}m$ of thickness with Nickel(16%). Also heat transfer characteristics based on hot wire arrangement is investigated and optimal hot wire system is developed. Developed control system detects overheating and stops the whole system on the long operating time. Developed kettle takes the performance evaluation test for volume expansion and satisfied for standard 'KS G3602'.

• Journal of Energy Engineering
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• v.17 no.2
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• pp.100-106
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• 2008

Flameless fiber mat catalytic burners have been known as an effective heat source in industrial drying processes since heat obtained from combustion can be transferred to absorptive body by far-infrared radiation. In order to extend the application of fiber mat catalytic burner, novel fiber mat catalytic burners were manufactured and combustion characteristics of them were investigated. For diffusive catalytic burners, the efficiency of combustion was significantly affected by the installation direction and the temperature of catalytic bed perimeter influenced on the diffusion rate of oxygen which determined the combustion efficiency of catalytic burner. It was seen in premixed catalytic combustion that air content in premixed fuel gas was optimized at slightly higher than theoretical amount of air. Combustion heat released higher than 70% by radiant heat in premixed catalytic combustion likewise diffusive catalytic combustion.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.6
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• pp.536-541
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• 2012

An instrumented pod has been developed to measure the aeroacoustic environment as well as the conventional data such as load, vibration, and aerodynamic heating of fighters during flight tests, confirming to the recently developed external pod design for fighters. This study presents the development of the measurement system in detail, being the first indigenous effort in its kind. The pod was designed to meet the requirements of the MIL-HDBK-1763 and MIL-STD-810 Method 515, which are the base to determine the locations and range of sensors. The Endevco 8510B-2 was selected as the sensor to withstand the harsh environment during the flight tests. In order to assess the integrity of the fabricated pod design, a ground run-up test of a KF-16 has been conducted with the pod installed at Station 5. The test results show that the system works well but the sound level exceeds the predetermined sensor range. The sensor range has been readjusted for flight test performed later.

• Fire Science and Engineering
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• v.23 no.6
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• pp.135-141
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• 2009

The composite truss has been widely used for tall buildings and long-span structures in North America. As compared with other similar structures, it has merits such as reduction of construction period, low span/depth ratio, low dead weight and so on. It has the most effective trait for structures with long span of 12~18m. After collapse of WTC, the fire resistance behaviors of structures have been actively conducted under various fire conditions in several country. This study showed that the surface temperature of steel member in the composit truss beam was reached to $700^{\circ}C$ under the fire condition of a short time. Under the same condition, the temperature in concrete was within $200^{\circ}C$. The composit truss beam with 20mm bracing was collapsed by rapid deflection after about 3minutes. However, the beams with 25mm, 35mm, and 45mm bracing were not collapsed, even though those were reached to deflection standard of L/20 within 15minutes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.85-88
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• 2011

In the trend of world wide environment preservation, researchers tried to find new environment friendly propellant instead of highly toxic propellant, Hydrazine. Among the candidates, ionic liquid propellants have lower toxicity, higher density, and higher specific impulse than Hydrazine. These ionic liquid propellants have high combustion chamber temperature, so catalyst supports such as gamma alumina cannot withstand in that temperature. Therefore, a catalyst that showed stable characteristic in high temperature is needed. Barium dopped alumina can be changed to Hexaaluminate in high temperature, and its characteristic in high temperature is superior than gamma alumina. Barium dopped Alumina is wet impregnated with Platinum and heated up to $1300^{\circ}C$ and $1400^{\circ}C$ for 2 hours. Those catalysts were examined by XRD, SEM, EDS, BET, and Drop test.

• Journal of Convergence for Information Technology
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• v.9 no.8
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• pp.155-163
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• 2019

Laminar mixed convection of a nanofluid consists of water and $Al_2O_3$ in a horizontal circular tube has been studied numerically. Two-phase mixture model has been used to investigate hydrodynamic and thermal behaviors of the nanofluid with variables physical properties. Three dimensional Navier-Stokes, energy and volume fraction equations have been discretized using the finite volume method. The Brownian motions of nanoparticles have been considered to determine the thermal conductivity and dynamic viscosity of $Al_2O_3$-Water nanofluid, which depend on temperature. The calculated results show good agreement with the previous numerical data. Results show that in a given Reynolds number (Re), increasing solid nanoparticles volume fraction and Richardson number (Ri) increases the convective heat transfer coefficient and wall shear stress.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.3
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• pp.187-194
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• 2019

The off-axis Infra-Red(IR) seeker is mounted on the nose cone side of the anti-air high speed missile to alleviate thermal shield effect due to aerodynamic heating. The seeker output can not be regarded as the Line-of-Sight(LOS) rate any more as missile's roll motion to keep the target tracking is associated. In this paper, we propose a method to calculate the LOS rate for off-axis seeker on a 2-axis gimbal. Firstly, true LOS rate equations are analytically derived but not implementable because boresight error rate is not measurable. And then the first order lag approximation to obtain boresight error rate is proposed. The proposed LOS rate calculation method can compensate the coupling effect by considering the rotations of missile and gimbal. The performance of the proposed method is verified via full nonlinear 6-DOF(Degree of Freedom) simulations.

• Food Engineering Progress
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• v.21 no.4
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• pp.403-408
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• 2017

Acetic acid bacteria strains were isolated from a variety of fermented foods and fallen fruits. Among them, the strain MAK88, whose acetic acid fermentation ability, acid-tolerance, and alcohol-tolerance were high, was selected and identified as Acetobacter orientalis. A seed culture of A. orientalis MAK88 was inoculated into onion juice, and the optimum conditions of acetic acid fermentation was investigated. The optimum initial concentration of ethanol in onion juice was 5% (v/v) and in that condition, acidity was 4.31% at 144 h of fermentation. The optimum initial concentration of acetic acid was 1% and the final acidity was 5.32%. The optimum fermentation temperature was determined to be $28^{\circ}C$. The most appropriate preparation method of onion juice was to heat the onion at $121^{\circ}C$ for 15 min and produce juice with pressure followed by filtering, and then sterilization at $121^{\circ}C$ for 15 min. Prepared onion juice was used for fermentation without dilution.

• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.21-29
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• 2021

The objective of this study is to evaluate the effect of the application of double layered bubble sheet on the curing of slab and wall concrete placed at the job site in cold weather and to offer a feasibility of Concrete IoT Management System(CIMS), which is wireless sensor network developed by the authors, to manage early age quality of the concrete in terms of temperature, maturity and strength development. Test results indicated that the application of bubble sheet enhances the insulation performance, which results in an increase of the temperature by around 1~20. 6℃. It is found that CIMS can gather the temperature, maturity and strength development data from the sensors embedded from 30 m far from CIMS successfully. Predicted compressive strengths by CIMS had good agreement with measured ones within 2 MPa error level until 7 days. It is thought that the combination of the bubble sheet application for cold weather protection and CIMS for quality management tool in cold weather concreting contributes to shorten the time for the form removal by one day.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4C
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• pp.283-290
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• 2006

Concrete has advantages in fire situations as it is non-combustible and has low thermal conductivity. However, concrete that is not designed against fire can experience significant explosive spalling from the build-up of pore pressures and internal tensile stresses when heated. In this study, the performance of wet-mixed high strength sprayed polymer mortar for fire resistance of tunnel system was evaluated by experimentally and numerically. The fire test was performed in fire resistance(electric) furnace according to RABT(Richtlinien fur die Ausstatung und den Betrieb von $Stra{\beta}entunneln$) time heating temperature curve, so as to evaluate the temperature distribution with cover thickness of wet-mixed high strength sprayed polymer mortar for fire resistance of tunnel system. Based on experimental results and numerical analysis, the proper cover thickness of wet-mixed high strength sprayed polymer mortar determined the more than 4cm.