• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.17-18
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• 2021

In the present study, Al-Zn coating was deposited by Arc thermal (AT) and plasma arc thermal (PAT) spray processes, and their corrosion characteristics were studied in 3.5% NaCl through electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) and mechanical tests. The bond adhesion result showed that plasma arc sprayed coating had a higher value attributed to compact, dense, and less porous coating compared to arc thermal spray coating which contains defects/pores and uneven morphology as revealed by scanning electron microscope analysis. Electrochemical results revealed that the plasma arc sprayed coating had a high polarization resistance at early stage of immersion, suggesting its excellent corrosion protection performance.

• KIEAE Journal
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• v.16 no.4
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• pp.71-77
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• 2016

Purpose : The energy saving in a residential building (apartment) sector is known as one of the effective solution of energy reduction. In South Korea, the government has recently reinforced regulations associated with the energy performance of buildings. However, there is a lack of research on the methods for the energy performance diagnosis that is used to analyze the wall thermal performance of the existing apartments. Because a reliable diagnosis is necessary to save the building energy, this study analyzed wall thermal performance of an existing apartment in Seoul. Method : This paper applied two methods for analysis of the thermal insulation performance; HFM(Heat Flow Meter) method and ASTR(Air-Surface Temperature Ratio) method. The HFM method is suggested by ISO9869-1 code to measure the thermal performance. The ASTR method is proposed by this study for the simplified In-situ measurement and it uses three temperature data (interior wall surface, interior and exterior air) and the overall heat transfer coefficient. This study conducted the experiment of an existing apartment in Seoul using these methods and analyzed the results. Furthermore, the energy simulation tool of the building was used to suggest retrofit of the building based on the results of measurements. Result : The error rate of HFM method and ASTR method was analyzed in about 17 to 20%. As the results of comparison between the initial design values of the wall and the measured values, the 26% degradation of insulation thermal performance was measured. Lastly, the energy simulation tool of the building shows 10.8% energy savings in accordance with the construction of suggested retrofit.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.120-129
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• 2012

As the recent advancement of automobile industry, there has been a great interest in the thermal comfort of the passengers inside the cabin of an automobile. Thermal comfort is affected by temperature, velocities, and mean radiation temperature of air, thermal resistance of clothes and physical active level of human. The present study performed computational analysis to select the location of air-conditioning vent that improves thermal comfort inside the cabin. In order to do this, we considered various air vent positions, and thermal flow analysis of each case is performed using CFD for the cabin with four passengers. The thermal comfort is evaluated using the computational results and the optimum location of air vent is suggested.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.754-761
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• 2013

Thermal displacement is an important issue in machine tool systems. During the last several decades, thermal error compensation technology has significantly reduced thermal distortion error; this success has been attributed to the development of a precise, robust thermal error model. A major advantage of using the thermal error model is instant compensation for the control variables during the modeling process. However, successful application of thermal error modeling requires correct determination of the temperature sensor placement. In this paper, a procedure for predicting thermal-mode-based thermal error is introduced. Based on this thermal analysis, temperature sensors were positioned for multiple heat-source models. The performance of the sensors based on thermal-mode error analysis, was compared with conventional methods through simulation and experiments, for the case of a slide table in a transient state. Our results show that for predicting thermal error the proposed thermal model is more accurate than the conventional model.

• Journal of ILASS-Korea
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• v.24 no.4
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• pp.203-208
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• 2019

In general, the oxi-nitriding method is well known as such a surface treatment way for substantial enhancement in corrosion resistance, even comparable to that of titanium. However, there are still lacks of information on thermal performance of the oxi-nitriding surface being of additional compound layers on the base substrate. Above all, the quantitative measurement of its thermal performance still was not evaluated yet. Thus, the present study experimentally measures the thermal resistance of the oxi-nitriding surface during droplet evaporation and then estimates heat transfer performance with the use of the onedimensional heat transfer model in vertical direction. From the experimental results, it is found that the total evaporation time slightly increased with the thermal resistance caused by the oxi-nitriding layer, showing a maximum difference of approximately 20% with that of the bare surface. Although the heat transfer performance of oxi-nitriding surface became slightly lower than that of the bare surface, the oxi-nitriding surface exhibits much better heat transfer performance compared to titanium.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.1
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• pp.62-66
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• 2011

In this study, the thermal performance of disk can be compared with disk and disk with holes through numerical analysis. The capacity of thermal emission on general disk becomes more than on disk with holes at the distribution of temperature at first and the magnitude of equivalent stress on general disk becomes less than on disk with holes at the distribution of stress. The capacity of thermal emission or the magnitude of thermal deformation on disk with holes becomes less than that on general disk 30 minutes later. The disk with holes is worn less and more durable than general disk. The performance of cooling and braking force at disk and pad can be improved by installing the disk with holes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.2
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• pp.229-239
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• 1998

The present paper examines the thermal and flow characteristics of a parallel flow heat exchanger and investigates the effects of the parameters on thermal performance by defining the flow nonuniformity. Thermal performance of a parallel flow heat exchanger is maximized by the optimization using Newton's searching method. The flow nonuniformity is chosen as an object function. The parameters such as the locations of separator, inlet, and outlet are expected to have a large influence on thermal performance of a parallel flow heat exchanger. The effect of these parameters are quantified by flow nonuniformity. The results show that the optimal locations of inlet and outlet are 19.73 mm and 10.9 mm, respectively. It is also shown that the heat transfer increases by 7.6% and the pressure drop decreases by 4.7%, compared to the reference model.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.8
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• pp.646-655
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• 2012

This study is intended to analyze the thermal performance and evaluate the applicability about non-duct type heat recovery ventilation system integrated with window. Eventually, economic analysis of the system is conducted according to building energy saving ratio of it. As results of the thermal performance, the U-factor of the window conducted on the basis of KS F 2278 appears to $1.8W/m^2K$, and the effective heat exchange efficiency of the ventilator conducted on the basis of KS B 6879 appears 49.95% for cooling, 66.89% for heating. In the applicability evaluated by TRNSYS 16, the caes of applying the heat recovery ventilator integrated with window is found to reduce the cooling or heating load by 2.9% or 13.5% than the non-ventilator case. The results of economic analysis taking a side of consumer is verified as the payback is 3 years, and the accumulated earning is 1,408,133 won in terms of '600,000 won/unit' for initial cost, 10 years for useful life of the system.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3164-3182
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• 2023

The CRUD on the fuel cladding under the pressurized water reactor (PWR) operating condition causes several issues. The CRUD can act as thermal resistance and increases the local cladding temperature which accelerate the corrosion process. The hideout of boron inside the CRUD results in axial offset anomaly and reduces the plant's shutdown margin. Recently, there are efforts to revise the acceptance criteria of emergency core cooling systems (ECCS), and additionally require the modeling of the thermal resistance effect of the CRUD during the performance analysis. There is an urgent need for the evaluation of the effect of the CRUD deposition on the cladding heat transfer under PWR operating conditions, but the experimental database is very limited. The experimental facility called DISNY was designed and constructed to analyze the CRUD-related multi-physical phenomena, and the performance analysis of the constructed DISNY facility was conducted. The thermal-hydraulic and water chemistry conditions to simulate the CRUD growth under PWR operating conditions were established. The design characteristics and feasibility of the DISNY facility were validated by the MARS-KS code analysis and separate performance tests. In the current study, detailed design features, design validation results, and future utilization plans of the proposed DISNY facility are presented.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.2
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• pp.97-107
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• 2004

Wall/floor intersection is important parts of a building envelope system. These intersections can be sources of thermal bridging effects and/or moisture condensation problems. This paper provides a detailed analysis of the thermal performance of wall/floor intersection. In particular, two-dimensional steady-state and transient solutions of the heat conduction within the wall/floor joint are presented. Various insulation configurations are considered to determine the magnitude of heat transfer increase due to wall/floor joint construction.