• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.252-261
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• 1999

The troubles such as slipping, pinching and other behaviors in the service of cold rolling mills often induce thermal shock crack on the surface of work roll, and considerably reduce their service lives. In order to evaluate thermal shock resistibility we use thermal shock tester generating frictional heat caused by a rotating disc contacting with test specimens. Thermal shock produces two heat affected layers below the roll surface, one is rehardened layer and the other is succeeding tempered layer. The maximum depth of crack occurred in a thermal shocked area is a criterion for the thermal shock resistibility. This paper describes on the investigation to the influence of hardness and residual stress.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.379-381
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• 1995

Many generating stations in korea are 25 years or more old, and are nearing the end of their planned life. Financial conditions and Site, Environment problems have made approval for construction of new stations increasingly difficult, and extending the life of an existing older plant may be a palatable alternative. Therefore, To determine whether generator rewinds are necessary to achieve an extended life, and Methods are required to estimate the proable remaining life of existing winding, here, We are going to estimate insolation condition through Nondestructive diagonostic test and Aging history tests of generator Stator winding and winding conditions through deterioration characteristics due to Heat cycle.

• Proceedings of the KIEE Conference
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• summer
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• pp.1073-1075
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• 2004

Permanent magnet high-speed machines are small size compared with general motor of the same power and so must minimize generating heat, as well rotor structure is simple and strong for born centrifugal force. Especially, Material of each part is given thermal limit therefore temperature distribution vary important. In this paper, heat transfer coefficient of permanent magnet high-speed machines with 5-kW 40,000 rpm is calculated and temperature distribution due to power loss is predicted by finite element analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.1
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• pp.74-81
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• 2016

The aim of this study was to find the initial design value of turbine blade for electrical type turbocompound system generating 10 kW. Turbocompound is one of the waste heat recovery system applying to internal combustion engine to recover exhaust gas energy that was about 30 % of total input energy. To design the turbine blade, 1-D mean line flow model was used. Exhaust gas temperature, pressure, flow rate and turbine rotating speed was fixed as primary boundary conditions. The velocity triangles was defined and used to determine the rotor inlet radius and width, the rotor outlet radius at shroud and radius at hub, the rotor flow angles and the number of blades.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.3
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• pp.133-138
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• 2020

As HMR (home meal replacement) food market grows rapidly, a new packaging with more HMR specialized functions is highly required to promote consumers' convenience. A susceptor is defined as a material generating heat by absorbing electromagnetic energy such typically as radiofrequency or microwave radiation. In microwave cooking, susceptors are made of conductive metal thin film deposited on paper or plastic sheet and have generally been used to help crispen or brown foods by converting microwave energy into heat. This mini review article deals with current status of microwave susceptor packaging including commercial products, technical theory, types of susceptor and a test method for heating performance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.160-161
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• 2022

This study is to investigate the temperature history over time of the cement mortar to confirm the bubble sheet insulation effect using the heat generat sheet. As a result of the experiment, it was confirmed that the heating effect was 6℃ higher on average than other types of sheets when the heating sheet is attached on the bottom of the double layered bubble sheet. For future research, it is planned to verify the heating performance by using the heating sheet under the same environmental conditions as the heating performance will be verified.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.39-40
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• 2022

This study is intended to examine the curing effect of the combination of the bubble sheet on the concrete by analyzing the temperature profile and core strength of the simulated concrete structure. The test results relvealed that the average temperature of the concrete applying photothermal sheet overlapped with the double bubble sheet at the bottom was 23.5℃, which had the highest insulation and insulation effect compared to other types of surface insulation curing sheets, and the core strength increased by up to 56%.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.56-61
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• 2009

Paradigm depending only on fossil fuel for building heat source is rapidly changing. Accelerating the change, as it has been known, is obligation for reducing green house gas coming from use of fossil fuel, i.e. reaction to United Nations Framework Convention on Climate Change. In addition, factors such as high oil price, unstable supply, weapon of petroleum and oil peak, by replacing fossil fuel, contributes to advance of environmental friendly renewable energy which can be continuously reusable. Therefore, current new energy policies, beyond enhancing effectiveness of heat using equipments, are to make best efforts for national competitiveness. Our country supports 11 areas for new renewable energy including sun light, solar heat and wind power. Among those areas, ocean thermal energy specifies tidal power generation using tide of sea, wave and temperature differences, wave power generation and thermal power generation. But heat use of heat source from sea water itself has been excluded as non-utilized energy. In the future, sea water heat source which has not been used so far will be required to be specified as new renewable energy. This research is to survey local heating system in Europe using sea water, central solar heating plants, seasonal thermal energy store and to analyze large scale central solar heating plants in German. Seasonal thermal energy store necessarily need to be equipped with large scale thermal energy store. Currently operating central solar heating system is a effective method which significantly enhances sharing rate of solar heat in a way that stores excessive heat generating in summer and then replenish insufficient heat for winter. Construction cost for this system is primarily dependent on large scale seasonal heat store and this high priced heat store merely plays its role once per year. Since our country is faced with 3 directional sea, active research and development for using sea water heat as cooling and heating heat source is required for seashore villages and building units. This research suggests how to utilize new energy in a way that stores cooling heat of sea water into seasonal thermal energy store when temperature of sea water is its lowest temperature in February based on West Sea and then uses it as cooling heat source when cooling is necessary. Since this method utilizes seasonal thermal energy store from existing central solar heating plant for heating and cooling purpose respectively twice per year maximizing energy efficiency by achieving 2 seasonal thermal energy store, active research and development is necessarily required for the future.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.721-724
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• 2011

A system to pressurize propellants stored in propellant tanks is necessary to feed liquid-propellants into combustion devices at the required pressure and flowrate without having cavitation in turbo-pumps. A pressurization system can be categorized into pre-pressurization stage and main-pressurization stage. This report is regarding to a main-pressurization system. Pressurization methods for propellant tanks are divided into pressurant gas generating method and pressurant gas feeding method. One of pressurant gas generating methods uses the vaporized oxygen gas from cryogenic liquid oxygen and non-flammable gas. In this report, both advantages and disadvantages for pressurization methods and types of pressurization systems are compared. Especially the characteristics and principle of pressurization system using impulsive control strategy applied in launch vehicles are introduced. Additionally the structure, schematics, and specifications of heat exchanger, which is one of main units in pressurization system are also discussed. This paper can be utilized to generate the conceptual requirements and to design preliminary configuration of pressurization system during the development of launch vehicle.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.5
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• pp.58-68
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• 2000

When SS400 steel was welded with low hydrogen type and ilmennite type welding, the effect of post-weld heat treatment(PWHT) was investigated with parameters such as micro vickers hardness, corrosion potential, polarization behaviors, galvanic current, Al anode generating current and Al anode weight loss etc. Hardness of each parts(HAZ, BM, WM) by PWHT in case of low hydrogen type and ilmennite type welding was lower than that of each parts by As-welded However hardness of WM area in case of low hydrogen type and ilmennite type welding was the highest among those three parts regardless of PWHT, Whereas in case of ilmennite type welding, WM area was the highest potential among these three parts on galvanic potential series with As-welded while BM area was the highest potential among these three parts by PWHT on the contrary. And in case of low hydrogen type welding, galvanic corrosion and micro cell corrosion of welding parts was decreased with PWHT. However, It was increased with PWHT in case of ilmennite type welding. Moreover Al anode generating current and anode weight loss in case of low hydrogen type was decreased by PWHT compared to As-wedled but, which was increased than that of As-welded in case of ilmennite type welding. Therefore, it is suggested that Corrosion resistance property in case of low hydrogen type welding is increased by PWHT. However its property was devreased with PWHT in case of ilmennite type welding.