• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.265-270
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• 2007

According to previous research, welding-induced residual stresses in steel structures can significantly affect the fatigue behaviour. Usually, high tensile residual stresses up to the yield strength are conservatively assumed at the weld toes. This conservative assumption can result in misleading fatigue assessments. Thee welding-induced residual stresses need be known in advance for a reliable fatigue assessment, which becomes possible to an increasing extent by numerical welding simulation. In this study, a fatigue Analysis technique for steel structures with welding induced residual stress is presented. First, We calculate the history of temperature according with welding process. Secondly, residual stress with a welding thermal history was evaluated by non-linear thermal stress analysis and lastly, fatigue strength is estimated with modified Goodman equation which can consider the effect of mean stress level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.4
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• pp.285-290
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• 2005

Mechanical properties of rubber mat are influenced by many factors such as compounding ingredients and states of cure, process of rubber, and fillers. Our study aim is to investigate influence of N-isopropyl-N'-chloro-P-phenylene diamine antioxidant on the thermal aging and ozone cracking. In this work, the degradation of antiblastic rubber mat was studied and suggested mechanism to involve two-types of degradation, thermal-aging and ozone-cracking both of which can be contained antioxidant or non-antioxidant.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.11
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• pp.434-443
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• 2016

The evaporation of water from an aqueous solution is widely used in the food, desalination, pulp, and chemical industries. Usually, a large amount of energy is consumed in the evaporation process to boil off water due to atmospheric pressure. As a way of improving the energy efficiency of the evaporation process, the combination of multiple effect evaporation and thermal vapor recompression has been proposed and has become a successful technique. In this study, 4 multiple-effect falling film type evaporators for sugar solution are designed and the energy efficiency of the system is analyzed in response to the selection of the steam ejector position. Energy efficiency is increased and vapor is more compressed in the steam ejector as the Thermal Vapor Recompression (TVR) is arranged in the rear part of the evaporator system. A simplified 0-dimensional evaporator model is developed using non-linear equations derived from mass balances, energy balances, and heat transfer equations. Steam economy is calculated to compare the evaporation performance of the 4 proposed evaporators. The entrainment ratio, compression ratio, and expansion ratio are computed to check the ejector performance.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.2
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• pp.47-54
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• 2020

Themo-mechanical analysis was carried out using the finite element method for the steel shell of a cupola furnace. When the outer surface of the shell was cooled with water to within the temperature range of 35-80 ℃ during operation of the cupola, the inner surface of the shell was expected to exhibit a temperature of 65-248 ℃ based on heat transfer analysis. The shell was also expected to have an equivalent stress range of 100-280 MPa in the outer surface over the temperature range examined. Upon cooling the shell to obtain an outer surface temperature <80 ℃, the maximum equivalent stress of the shell did not exceed the yield strength. Although the temperature of the outer surface varied between 35 and 80 ℃ periodically due to the cooling control problem, the fatigue stress at the outer surface of the shell was calculated to be within the fatigue strength. During a non-operational period to examine the system between furnace operations, the thermal stress presented in the shell was sufficiently low to reach the desired yield strength and fatigue limit.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.104-110
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• 2019

The thermal decomposition characteristics of boron-potassium nitrate ($BKNO_3$) were investigated by non-isothermal thermal gravimetric analysis (TGA). Two steps of mass loss were observed in the temperature range between room temperature and $600^{\circ}C$. Kinetic parameters of the thermal decompositions were evaluated from the measured TGA curves using the AKTS Thermokinetics Software. For the first step of mass loss ($220-360^{\circ}C$) corresponding to the thermal decomposition process of the binder (Laminac/Lupersol), the activation energy is in the range of approximately 120-270 kJ/mol when evaluated by Friedman's iso-conversional method, while the value of activation energy varies in the range of approximately 150-400 kJ/mol during the second step process ($360-550^{\circ}C$).

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.665-670
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• 2001

The purpose of this study is to develop a new type dryer, which is to proceed mixing and drying of wet-materials at the same time and drying process is carried out in a closed system. In this drying system, thermal contact occurs, when a fluidized zone is created by paddle mechanism. Accordingly, wet-materials is dried in a short time without any damage. Also wet-materials could be dried uniformly to low moisture contents. It is suitable to dry a small quantity of multi-kind materials. And drying process is carried out in a closed system, so as for environmental pollution dust not to be emitted into the atmosphere. Accordingly, it could be used to dry not only food and chemical materials, but also environmental pollution materials.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.12-15
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• 1994

To establish the sea surface temperature estimation scheme for the upcoming advanced remote sensor, the quasi-analytical solution of the approximated radiative transfer equation which express the radiative transfer process of the radiant energy radiated from the sea surface to the satellite is approximated into the non-linear equation. To solve the simultaneous approximated radiative transfer equation which express the radiative transfer process of the radiant energy radiated from the sea surface to the satellite is approximated into the nonlinear equation. To solve the simultaneous approximated radiative transfer equation at each channel, the constrained non-linear optimization technique is adopted. To define the coefficients of the approximated radiative transfer equation and the constraints, the satellite detected radiance and the total transmittance are computed from the 1350 kinds of simulated atmosphere / surface models via radiative transfer code. The verification from the simulated data show the sufficient result.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.352-357
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• 1999

During the cooling process of rail, residual stresses are produced due to the difference of the coefficients of thermal expansion between rail and inhomogeneous non-metallic inclusions such as sulphides and oxides. A micro-mechanical approach is used to obtain the stresses in the inclusions and matrix, After obtaining the stress of an elliptical inhomogeneous inclusion in an infinite domain, average stresses of randomly distributed spherical inclusions are obtained by use of Mori-Tanaka's self consistent method. The magnitude of the calculated residual stress is near to the yield stress of the matrix in case of the spherical inclusions.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.1
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• pp.41-49
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• 2022

Recently interests on the application of thermal cameras have increased with the advance of image analysis technology. Aside from a simple image acquisition, applications such as digital twin and thermal image management systems have gained popularity. To this end, we studied the effect of emissivity on the DN (Digital Number) value in the process of derivation of a relational expression for converting DN to an actual surface temperature. The DN value is a number representing the spectral band value of the thermal image, and is an important element constituting the thermal image data. However, the DN value is not a temperature value indicating the actual surface temperature, but a brightness value indicating high and low heat as brightness, and has a non-linear relationship with the actual surface temperature. The reliable relationship between DN and the actual surface temperature is critical for a thermal image processing. We tested the relationship between the actual surface temperature and the DN value of the thermal image, and then the radiation adjustment was performed to better estimate actual surface temperatures. As a result, the relation graph between the actual surface temperature and the DN value similarly show linear pattern with the relation graph between the radiation-controlled non-contact thermometer and the DN value. And the non-contact temperature after adjusting the emissivity was closer to the actual surface temperature than before adjusting the emissivity.

• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.2
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• pp.1-13
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• 2011

The recent spotlight on electronic touch-screen display, a rapid breakthrough in the information society is evolving. Touch panel input device such as a keyboard or mouse without the use of, the on-screen character or a specific location or object on the person's hand touches a particular feature to identify the location of a panel is to be handled. The touch screen on the touch panel is used in the Ag paste is used mostly for low-curable paste. The thermal-curing paste according to the drying process of thermal energy consumption and improve the working environment of organic solvents have problems. In this study, Ag paste used in the non-thermal curing friendly and cost-effective UV curable paste was prepared. Current commercially available thermal-curable binder, was used instead of the flow characteristics of UV-curable oligomers and monomers with functional groups to give a single conductive Ag paste with the addition of a pattern could be formed. Ag paste as a result, thermal-curing adhesive, hardness, resistance and excellent reproduction of fine patterns and was available with screen printing environmentally friendly could see its potential as a patterning technology.