• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1201-1212
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• 1999

A numerical analysis is performed to predict the thermal response and ablation rate for charring or non-charring material which is designed to be used as thermal protection system (TPS). The numerical program composed of in-depth energy balance equation and the aerotherm chemical equilibrium (ACE) program. The ACE program calculates various thermochemical state from ablation products. The developed numerical program is verified by comparing the reported results from literature. The sensitivity tests for input parameters are performed. The thermal behavior of ablating material is mainly affected by density of ablating material, convective heat transfer coefficient and recovery enthalpy of flow field.

• Geomechanics and Engineering
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• v.10 no.1
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• pp.49-57
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• 2016

The high permeability-high strength concrete belongs to the typical of porous materials. It is mainly used in underground engineering for cold area, it can act the role of heat preservation, also to be the bailing and buffer layer. In order to establish a suitable model to predict the thermal conductivity and directly applied for engineering, according to the structure characteristics, the thermal conductivity predicting model was built by resistance network model of parallel three-phase medium. For the selected geometric and physical cell model, the thermal conductivity forecast model can be set up with aggregate particle size and mixture ratio directly. Comparing with the experimental data and classic model, the prediction model could reflect the mixture ratio intuitively. When the experimental and calculating data are contrasted, the value of experiment is slightly higher than predicting, and the average relative error is about 6.6%. If the material can be used in underground engineering instead by the commonly insulation material, it can achieve the basic requirements to be the heat insulation material as well.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.4
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• pp.88-96
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• 2002

The CSCM Upwind method and Material Transport Analysis(MTA) have been used to predict the thermal response and shape changes for charring/non-charring material which can be used as thermal protection material(TPM) on blunt-body nose tip. We performed intensive flight trajectory simulations to compare 1-D MTA results with those of 2-D/Axisymmetric MTA by using MTAs and Navier-Stokes code. Theheat-transfer rate and pressure distribution were predicted at selected altitudes and wall temperature along the flight trajectory and the shape changes of blunt-body nose tip were predicted subsequently by using current procedure.

• Journal of The Korean Digital Architecture Interior Association
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• v.12 no.4
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• pp.59-66
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• 2012

This study is interested in identifying the effectiveness of alkali-activated fire protection material compounds including the alkali-activator such as potassium hydroxide, sodium silicate and fly ash as the fire resistant finishing materials. Also, this paper is concerned with change in compressive strength and pore structure of the alkali-activated fire protection material at high temperatures. The testing methods of fire protection materials in high temperature properties are make use of TG-DSC and mercury intrusion porosimetry measurements. This study results show that compressive strength is rapidly degraded depending on a rise of heating temperature. Porosity showed a tendency to increase irrespective of specimen types. This is due to both the outbreak of collapse of gel comprising the cement and a micro crack by heating. However, alkali-activated fire protection material composed of potassium hydroxide, sodium silicate and fly ash has the thermal stability of the slight decrease of compressive strength and porosity at high temperature. These thermal stability is caused by the ceramic binding capacity induced by alkali activation reaction by the reason of the thermal analysis result not showing the decomposition of calcium hydrate.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.79-85
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• 2018

The demand for the development of atmospheric entry vehicles, dealing with reentry and solar-system planet exploration, is increasing. Generally, atmospheric drag and heating accompany the entry into atmospheric air. Accordingly, the selection of the thermal protection materials and the design and application of the thermal protection system are very important. In this paper, the atmospheric entry environment and the type and characteristics of the thermal protection materials are discussed. The design and application status of a thermal protection system for spaceplanes are described.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.190-193
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• 2001

ZnO varistors have been widely used to protect power system and electronic system against overvoltages based on their excellent nonlinearity. In order to increase their protection capability, the fracture and protection technologies of arresters have to study according to their applications, namely ImA DC voltage, leakage currents, impulse residual voltages, withstanding capability to impulse surge, and energy absorption capability. ZnO varistors which have nonlinear current-voltage characteristic name a number of failure mechanism when ZnO elements absorb surge energies. Failure mode by thermal stress and Pin hole are among the most common failure mechanism at the high current surge current. In this study, the fracture mechaism of power arresters are introduced and protection technologies are researched. In particular the effect of thermal stress by surge currents to ZnO elements and methods against arc surge energy through withstand structure design of arrester are discussed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.355-363
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• 2021

Heat resistance performance evaluation and thermal analysis were performed to confirm the applicability of the lyocell-based carbon/phenolic composite material for heat-resistant parts for aerospace. Heat resistance performance evaluation of carbon/phenolic was conducted by Thermal Protection Evaluation Motor (TPEM). In this paper, boundary layer integration code considering the boundary layer analysis of combustion gas and MSC-Marc 2018 considering ablation and thermal pyrolysis were used for the thermal analysis. The ablation and thermal insulation performance were analyzed by the pressure curve of test motor and the cut carbon/phenolic specimens. The thermal response of the lyocell-based carbon/phenolic material was similar to that of the rayon-based carbon/phenolic material. Based on the results through the combustion test, the applicability of heat-resistant parts for aerospace to which domestic lyocell-based carbon fibers were applied was confirmed.

• KIEAE Journal
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• v.15 no.6
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• pp.11-18
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• 2015

Purpose: The current study analyzed trends in thermal insulation performance with aging, and condensation characteristics caused by the former. Method: Thermal insulation and condensation prevention performance of an architecture were assessed using Temperature Difference Ration Inside, or TDRi. Subjects of this quantitative analysis in thermal insulation performance change due to aging included recently constructed apartments and aged apartments older than 40 years. Time series comparison and analysis were conducted to observed changes in the thermal insulation performance and condensation characteristics. Result: Analysis showed that wall insulation performance degraded with aging regardless of fortified insulating material usage or insulating material type, which caused increased danger of condensation. In addition, when fortified insulating material was installed on the connection between the walls, insulation performance degradation was lower compared to cases in which fortified materials were not used. In all cases from 1 to 10, the rate of thermal insulation performance degradation increased after 20 years of aging.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.493-510
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• 2021

Mineral wool is an insulation material commonly used in passive fire protection (PFP) systems on offshore installations. Insulation materials have only been considered functional materials for thermal analysis in the conventional offshore PFP system design method. Hence, the structural performance of insulation has yet to be considered in the design of PFP systems. However, the structural elements of offshore PFP systems are often designed with excessive dimensions to satisfy structural requirements under external loads such as wind, fire and explosive pressure. To verify the structural contribution of insulation material, it was considered a structural material in this study. A series of material tensile tests was undertaken with two types of mineral wool at room temperature and at elevated temperatures for fire conditions. The mechanical properties were then verified with modified methods, and a database was constructed for application in a series of nonlinear structural and thermal finite-element analyses of an offshore bulkhead-type PFP system. Numerical analyses were performed with a conventional model without insulation and with a new suggested model with insulation. These analyses showed the structural contribution of the insulation in the structural behaviour of the PFP panel. The results suggest the need to consider the structural strength of the insulation material in PFP systems during the structural design step for offshore installations.

• Journal of the Korean institute of surface engineering
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• v.48 no.6
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• pp.343-348
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• 2015

In this paper, arc Zn thermal spray coating was carried out on the SS400 steel, and then various electrochemical characteristics and surface damage behavior of Zn thermal spray coating layer were analyzed. As the results, the potential of Zn thermal spray coating layer presented driving voltage above 300 mV compare to that of SS400 steel. The passivity characteristic in anodic polarization curve was not presented. It was adequate to as sacrificial anode material. In the surface damage after galvanostatic experiments, uniform corrosion tendency of Zn thermal spray coating layer was clearly observed with acceleration of the dissolution reaction. In conclusion, Zn thermal spray coating could be determined to represent the corrosion protection effect by stable sacrificial anodic cathodic protection method in seawater because it had sufficient driving voltage and uniform corrosion damage tendency for the SS400 steel.