• 한국태양에너지학회:학술대회논문집
• /
• 2012.03a
• /
• pp.280-285
• /
• 2012

It is important to produce the high temperature and high pressure air for the concentrated solar power system using the combined cycle. In this paper, based on the concept of tubular receiver, we designed two types with focus on radiation loss reduction. These two receivers were tested in the KIER solar furnace of 40kW thermal capacity. Performance of the two receivers were evaluated and compared.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.597-603
• /
• 2010

Metallic sintered brake pads are often applied to Mid/High Speed Train due to its high strength and thermal characteristics. Because of its imbalance contact between discs and pads can greatly influence the life span, one sided wear, discs attack/crack and threat the safety of the train during operation. In this research, we analyzed pressure/temperature distribution between brake pads and disks. Analyzed data had been verified and modified to conduct further tests of Flexible brake pads with small/full-scale dynamo test. Flexible brake pads were installed to TTX train to conduct further tests to identify the differences between Rigid brake pads and Flexible brake pads. In result, Flexible brake pads showed outstanding disk thermal stability, one sided wear, noise and life of pad than rigid brake pad.

• Journal of the Optical Society of Korea
• /
• v.20 no.1
• /
• pp.125-129
• /
• 2016

In this study, we have investigated a high-temperature AlN nucleation layer and AlGaN epilayers on c-plane sapphire substrate by low-pressure metal-organic chemical vapor deposition (LP-MOCVD). High resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), scanning electron microscope (SEM) and Raman scattering measurements have been exploited to study the crystal quality, surface morphology, and residual strain of the HT-AlN nucleation layer. These analyses reveal that the insertion of an LT-AlN nucleation layer can improve the crystal quality, smooth the surface morphology of the HT-AlN nucleation layer and further reduce the threading dislocation density of AlGaN epifilms. The mechanism of inserting an LT-AlN nucleation layer to enhance the optical properties of HT-AlN nucleation layer and AlGaN epifilm are discussed from the viewpoint of driving force of reaction in this paper.

• Korean Journal of Pharmacognosy
• /
• v.21 no.4
• /
• pp.284-289
• /
• 1990

Crude Aconiti Tubers were irradiated with microwave for 5 or 10 min with or without $NaHCO_3$. Ten min-irradiation reduced the contents of aconitine and mesaconitine to the level of those of commercially available processed Aconiti tuber power which is prepared with the high pressure-high temperature technique. The contents of benzoylaconine of the 10 min-irradiated Aconiti tubers were also comparable to those of commerciallized processed Aconiti tuber powder. However, irradiation with 1% $NaHCO_3$ soln. resulted in the drastic reduction of all the three above alkaloids.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1661-1662
• /
• 2008

After steam turbines in power plant drives generator and maintains it at rated speed using high temperature and high pressure steam energy, they regulate the output of generator when synchronized in parallel with the power system. By the way, as the steam flow into turbine can not be reduced fast even though the electrical load is lost, the turbine gets into dangerous situation due to the increase of its speed. At this time, the duty of the turbine governor is "how to limit the speed within its overspeed trip setpoint and escape from danger." In order to implement this purpose, there are various ways different from valve position control. So, in this paper, the various methods for overspeed protection are introduced in comparison with valve position control.

• Proceedings of the KSME Conference
• /
• 2000.04a
• /
• pp.13-18
• /
• 2000

Nowadays, 60 percent of thermal power plants already have been operated over their own design life. These operations of old power plant over their design life have caused a fracture accident of degradation a loss of economic and human. Therefore, the new life assessment and prediction technology is necessary to improve the safety and reliability of high pressure and high temperature power plant facilities. In this paper, innovative electrochemical test method have been used and results have been compared to the conventional test. Finally, the electrochemical test is applied to the in-field HP turbine and a database is currently in progress for the development of the life assessment standard and procedure.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.996-999
• /
• 2008

Aspheric polymer lens fabrication using isothermal compression molding is presented in this paper. Due to increasing definition of an image sensor, higher precision is required by a lens which can be used as a part of an imageforming optical module. Injection molding is a factory standard method for a polymer optical lens. But achievable precision using injection molding has a formidable limitation due to the machining of complex mold structure and melting and cooling down a polymer melt under high pressure condition during forming process. To overcome the precision requirement and limitation using injection molding method, isothermal compression molding is applied to fabrication of a polymer optical lens. The fabrication condition is determined by numerical simulations of temperature distribution and given material properties. Under the found condition, the lens having a high precision can successfully be reproduced and does not show birefringence which results often in optical degradation.

• Journal of Korea Foundry Society
• /
• v.28 no.4
• /
• pp.166-169
• /
• 2008

This study deals about the development of fusible core with low melting temperature by addition of ceramic particles. A new concept of salt core was introduced to produce an integrated casting part having a complicated inner shape or requiring under-cut in high pressure die casting or squeeze casting process. The mechanical properties of fusible core were improved due to the addition of ceramic particles which helped to produce fine microstructure. The new technology for the preparation of new fusible core materials which possess high compression strength was established. Addition of ceramics particles increased the mechanical properties of fusible core materials. There was an increasing relationship between percentage of ceramic particles and mechanical strength was existed up to 60%.

• 한국연소학회:학술대회논문집
• /
• 2012.04a
• /
• pp.151-152
• /
• 2012

Collectors connected to diesel engine exhaust pipe for application of PM reduction facilities which was used to reduce PM from the exhaust gas produced from ship, Filtration performance of PM was tested. In this system, it was confirmed that the bag house can remove over 90 percent of PM from a lot of high temperature and high pressure gases produced in diesel engine. The results obtained from performance test show the potential possibility for commercialization of ceramic filter collectors which is applied to reduction facilities of flue gas produced from a diesel engine on the ship.

• Journal of the korean Society of Automotive Engineers
• /
• v.4 no.2
• /
• pp.58-68
• /
• 1982

It is well known to diesel engineers that the heat release pattern is one of the most important factors affecting engine performance. Thorough research in heat release pattern has materially helped the progress in high-speed diesel engine development . This paper is based on the research conducted at KAIST and Daewoo Heavy Industry last year. The purpose of this paper is to determine the heat release pattern in combustion chamber of MAN M type, the famous low-noise engine. Thermodynamic cycle simulation was performed using Whitehous-Way's heat release pattern with modified coefficients and Annand's heat transfer model. Instantaneous temperature and pressure of gas in cylinder could be determined by the numerical solution of simultaneous equation of mass conservation, equation of energy conservation, and state equation of ideal gas. Calculated results were compared with measured values in some details emphasizing upon the factors affecting rate of heat release. The agreement was fairly good and revealed why M type should have lower burning velocity at the early part of combustion in spite of high injection rate. Additional results by parametric studies were given in relation to fuel injection conditions for further application to engine development.