• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 춘계학술발표대회 개요집
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• pp.111-113
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• 2003

The existing heating unit is indirect-heating method that make use or the nichrome wire or halogen lamp. The indirect-heating method has the demerits of long warming time, high power consumption and many organization parts. In this study, the heating unit of direct-heating method manufactured as being the thermal spray coating of conductive heating material on the surface of heating unit in order to improve the demerits of indirect-heating method. And YSZ added Ni-20Cr that had moderate electrical resistivity was chosen of the conductive heating material.

• Applied Biological Chemistry
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• 제40권3호
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• pp.220-224
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• 1997

아밀로오스 함량이 다른 옥수수 전분에 전분과 물의 비율을 1:3.5와 1:9로 조절하고 $100^{\circ}C$와 $121^{\circ}C$에서 가열-냉각 처리를 4회까지 반복한 후, 효소-중량법과 ${\alpha}-$아밀라아제(Bacillus subtilis)를 이용한 효소법으로 효소저항전분을 분리하여 수분함량과 가열-냉각 방법에 따른 효소저항전분의 수율을 비교하였다. 같은 처리를 한 경우에는 효소-중량법이 ${\alpha}-$아밀라아제를 사용한 효소법보다 효소저항전분의 분리능이 더 큼을 알 수 있었다. 분리 방법에 상관없이 아밀로오스 함량이 높고, 가열-냉각 처리 횟수를 증가시키면 효소저항전분의 수율도 증가하였으며, 가열온도는 $100^{\circ}C$보다 $121^{\circ}C$에서, 수분함량은 전분과 물의 비을이 1:9보다 1:3.5의 조건에서 높은 수율을 보였다.

• 한국결정성장학회지
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• 제25권3호
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• pp.85-92
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• 2015

SiC 결정은 전력반도체 소자용 소재로서 지금까지 외국은 물론 국내에서도 많은 연구가 이루어지고 있으며, 지금까지 고주파 유도가열 방식을 이용한 승화법으로 성장되어 왔다. 그러나, SiC 단결정은 결정 성장 계면에서의 온도 안정성에 따라 쉽게 다른 다형으로 성장하기 때문에, 고품질의 결정을 얻기 위해서는 결정성장 계면에서의 안정적인 온도 구배가 필요하다. 본 논문에서는 저항가열 방식을 이용한 승화법 성장 장치를 이용하여 종자결정을 사용하지 않은 상태에서 SIC 다결정상을 성장하여 보고, 성장 양상에 대하여 고찰하고자 하였다. SiC 다결정상은 성장속도 0.02~0.5 mm/hr로 성장되었으며, 성장된 SiC 다결정상의 두께는 0.25 mm~0.5 mm이고, 이 때 도가니 하부의 온도는 $2100{\sim}2300^{\circ}C$, 성장 압력은 10~760 torr의 범위에서 조절되었다. 성장된 다결정상 결정은 광학현미경으로 관찰하여, 성장 거동을 고찰하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
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• pp.111-114
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• 2011

Waterprooping Method with sheet need to study technology and multilateral verification considering the arctic conditions as low temperature and humidity, which is the result only considered of material aspects without environmental condition in construction But there are no measures up until now. To solve this problem by using high frequency induction heating method developed waterproof sheets, cold (5 ℃ or less) can be applied in a more stable environment, water-resistant materials and construction methods were studied for development. The results of the test showed that high frequency induction heating method is effective for usability in low temperature condition and securement of proper quality than existing Waterprooping Method with sheet need.

• 한국안전학회지
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• 제26권5호
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• pp.65-72
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• 2011

The use of waste concrete can resolve the environmental pollution and shortage of natural aggregate. However, recycled aggregate includes substantial amount of cement paste. So, these aggregates are more porous, and less resistant to mechanical actions than natural aggregates. So, recently, the new manufacture processes of high quality recycled aggregates were suggested such as heating and solving to acid liquid. But the method of solving to acid liquid is not economical and produces additional environmental pollution. In this paper, for the purpose of manufacture of high quality recycled aggregates, the heating processes was added to the existing process of recycled aggregates. To find the optimum process, the experiment was performed by using the method of statistical experiment design, and the heating temperatures(4 levels : 300, 450, 600 and $750^{\circ}C$) and heating times(4 levels : 5, 20, 40, 60 minute) were main experimental variables. By the test results, the optimum manufacturing condition of coarse recycled aggregate was $600^{\circ}C$ and 40 minute, and for the fine recycled aggregate, a little heating made a satisfaction to the KS standard quality code.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.685-692
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• 2024

Currently used heating elements are metal and non-metal heating elements, including various types of heaters, and resistance line heating elements have a problem of decreasing thermal efficiency over time, so to solve this problem, a planar heating element using high-purity carbon materials and oxidation-resistant inorganic compounds was applied. Through the manufacture of planar heating elements using CNT, ruthenium composite materials, and ruthenium oxide, physicochemical performance and capacity were increased, and instantaneous responsiveness was increased. Through thick film technology applicable to various base bodies, fine patterns were formed by the screening method in consideration of the fact that the performance of the heat source depends on the viscosity and pattern shape. The heating element was manufactured by thick film printing technology by mixing ruthenium oxide, CNT, Ag, etc. The characteristics of each paste were analyzed through viscosity measurement, and STS 430 was used as a base. Surface temperature and efficiency were measured by testing heaters manufactured for small wind tunnels and real-vehicle experiments. The surface temperature decreased as the air volume increased, and the optimal system boundary was found to be about 200 mm. Among the currently used heating elements, this paper manufactured a planar heating element using thick film technology to find out the relationship between air volume and temperature, and to study the surface temperature.

• Journal of Mechanical Science and Technology
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• 제14권3호
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• pp.298-305
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• 2000

The functionally graded material (FGM) is the new concept for a heat resisting material. FGM consists of ceramics on one side and metal on the other. A composition and microstructure of an intermediate layer change continuously from ceramics to metal at the micron level. This study is carried out to analyze the thermal shock characteristics of functionally graded PSZ/ metal composites. Heat-resistant property was evaluated by gas burner heating test using $C_2H_2/O_2$ combustion flame. The ceramic surface was heated with burner flame and the bottom surface cooled with water flow. Also, the composition profile and the thickness of the graded layer were varied to study the thermo mechanical response. Furthermore, this study carried out the thermal stress analysis to investigate the thermal characteristics by the finite element method. Acoustic emission (AE) monitoring was performed to detect the microfracture process in a thermal shock test.

• 한국안전학회지
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• 제36권2호
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• pp.10-17
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• 2021

This paper presents the robust design of each component used in the development of an induction bolt heating system for dismantling the high-temperature high-pressure casing heating bolts of turbines in power plants. The induction bolt heating system comprises seven assemblies, namely AC breaker, AC filter, inverter, transformer, work coil, cable, and CT/PT. For each of these assemblies, the various failure modes are identified by the failure mode and effects analysis (FMEA) method, and the causes and effects of these failure modes are presented. In addition, the risk priority numbers are deduced for the individual parts. To ensure robust design, the insulated-gate bipolar transistor (IGBT), switched-mode power supply (SMPS), C/T (adjusting current), capacitor, and coupling are selected. The IGBT is changed to a field-effect transistor (FET) to enhance the voltage applied to the induction heating system, and a dual-safety device is added to the SMPS. For C/T (adjusting current), the turns ratio is adjusted to ensure an appropriate amount of induced current. The capacitor is replaced by a product with heat resistance and durability; further, coupling with a water-resistant structure is improved such that the connecting parts are not easily destroyed. The ground connection is chosen for management priority.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.828-836
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• 2008

To develop an engineering-model of hydrogen-fueled ultra-micro combustor for Ultra Micro Gas Turbine(UMGT), we reviewed and summarized the problems in downsizing combustors, and determined a suitable burning method. The key issue to actualize practical ultra-micro combustors is reducing heat loss from the combustor to compressor and turbine. The reduction of heat loss was discussed from 3 different viewpoints; heat-insulation material, high-space-heating-rate combustion, and combustor-insolated gas turbine structure. Use of heat-insulation material induced the heat loss reduction to the surroundings. The heat loss ratio decreased substantially in reverse proportion to space heating rate, leading the idea that it could be reduced by burning at a high space heating rate. By settling the combustor insolated from the compressor and turbine, the heat transfer from the combustor to the compressor and turbine becomes smaller. For a selection of the suitable burning method, comparison between 2 burning methods, flat-flame and swirling-flamer types, was conducted. Synthetically the flat-flame burning method was confirmed to be more suitable for ultra-micro combustors than latter one. Base on them, an engineering-model of hydrogen-fueled flat-flame ultra-micro combustor was developed. To obtain high overall heat-insulation, heat-resistant and strength, the engineering-model combustor had triple layer structure with an advanced ceramic, a heat insulation material and a stainless steel. To simplify heat transfer issue in the combustor, it was isolated from the other components. Furthermore it was designed by considering structure, size, material, velocity, pressure loss and prevention of flashback.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.24-25
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• 2016

Concrete has been recognized as a material which is resistant to high temperatures, but chemicophysical property of concrete is changed by the high temperature. So, mechanical properties of concrete may be reduced. So, concrete at high temperature is evaluated mechanical properties for safety inspection. However, research of ultrasonic method is not much. Therefore, the purpose of this study is to NDT(non-destructive test) of 30, 70, 110MPa concrete exposed high temperature using ultrasonic pulse velocity and amplitude.