• Journal of Technologic Dentistry
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• v.34 no.1
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• pp.11-21
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• 2012

Purpose: Densification and mechanical properties of dental zirconia ceramics were evaluated by different sintering methods. Materials and Methods: Y-TZP zirconia block(Kavo $Everest^{(R)}$ ZS blank, Kavo dental GmbH, Bismarckring, Germany) was used in this study. Sintering were performed in heat sintering furnace and microwave sintering furnace, and then experimented and analyzed on a change in densification according to the sintering time, a change in densification according to thickness, flexural strength and micro-structure in zirconia specimens. Results: Microwave sintering was very effective in considerable mechanical properties such as flexural strength and bulk density was drastically increased than conventional electric heating method. It is also shown that microwave sintering time was faster and more economical than common method to be present in qualities which equal or exceed. Conclusion: It will be important to seek the accurate sintering condition of dental zirconia by microwave sintering method and the continuous research is necessary for the study of relationship between sintering methods and mechanical properties.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.129.2-129.2
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• 2010

As a part of the government renewable energy policy, KOWEPO is constructing 300MW IGCC plant in Taean. IGCC plant consists of gasification block, air separation unit and power block, which performance test is separately conducted. Overall performance test for IGCC plant is peformed to comply with ASME PTC 46. Major factors affected on the overall efficiency for IGCC plant are external conditions, each block performance(gasification, ASU, power block), water/steam integration and air integration. Performance parameters of IGCC plant are cold gas efficiency, oxygen consumption, sensible heat recovery of syngas cooler for gasification block and purity of oxygen, flow amount of oxygen and nitrogen, power consumption for air separation unit and steam/water integration among the each block. The gas turbine capacity applied to the IGCC plant is 20 percent higher than NGCC gas turbine due to the low caloric heating value of syngas, therefor it is possible to utilize air integration between gas turbine and air separation unit to improve overall efficiency of the IGCC plant and there is a little impact on the ambient condition. It is very important to optimize the air integration design with consideration to the optimized integration ratio and the reliable operation. Optimized steam/water integration between power block and gasification block can improve overall efficiency of IGCC plant where the optimized heat recovery from gasification block should be considered. Finally, It is possibile to achieve the target efficiency above 42 percent(HHV, Net) for 300MW Taean IGCC plant by optimized design and integration.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.1
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• pp.28-34
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• 2016

Far-infrared radiation ceramic is an attractive material that provides thermal therapy by permeating the infrared rays into the deep inside of the human skin. Therefore, it is currently used for thermal therapy devices, thermal mat, heating equipment and so on. This work aims to optimize the sintering process of the far-infrared radiation ceramic with the process parameters of temperature and time. A variety of characterization tools have been used to investigate the optimal sintering condition of far-infrared radiation. The phase of far-infrared radiation ceramic was characterized by using X-ray diffraction (XRD) and microstructure of fracture surface was studied by scanning electron microscopy (SEM). The FT-IR was also performed to measure the far-infrared emissivity.

• Journal of Ocean Engineering and Technology
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• v.22 no.5
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• pp.7-24
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• 2008

Masan-Jinhae Bay, in Korea, is known for its frequent algal bloom outbreaks. This study was conducted in order to examine the environmental characteristics of the area, with the aim of identifying indicators that could be used to speculate about future algal blooms. The water temperatures and salinities in Haengam Bay, one of the small inner bays within Jinhae, appeared to re relatively higher than those in Masan and Jinhae bays, across most seasons. Furthermore, stratification begins to develop in all three regions from spring to summer as a result of the local heating effects and an increase in the efficient from the surrounding land. As a result, anoxic conditions appear near the bottom layer of the bay, leading to the deterioration of water quality, which has been identified as one of the causes of bloom outbreaks. Compared to Haengam and Jinhae bays, concentrations of DIN and DIP were remarkably higher in Masan Bay. However, the mean ratio of DIN to DIP was 3.3$\sim$13.6 in all three regions throughout the year, suggesting that nitrogen can function as a growth-limiting factor for phytoplankton. The results of mathematical models showed that cumulative organic pollutants may be a trigger for direct algal bloom occurrences, since residual tidal currents appeared to be less than $3\;cm\;\cdot\;s^{-1}$. Furthermore, computed DO concentrations in the four small inner bays of Jinhae during the summer appeared to be $3\;cm\;\cdot\;l^{-1}$ indicating a hypoxic state. Likewise, computed Chl-a concentrations turned out to be more than $0.01\;mg\;\cdot\;l^{-1}$, indicating eutrophication across most seasons. Based on the overall results, Masan-Jinhae Bay appeared to possess a very high potential for algal bloom outbreaks at anytime during the year.

• Korean Journal of Food Science and Technology
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• v.23 no.4
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• pp.490-497
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• 1991

Kongjaban (a Korean-style seasoned black soybean) prepared under various conditions such as different soaking temperatures and time, cooking rate, and amounts of sugar and soy sauce was investigated with respect to its physical and sensory qualities. Soaking soybeans in water at $20^{\circ}C$ and $60^{\circ}C$ prior to heating decreased the hardness, degree of browning and saltiness of kongjaban, regardless of soaking temperature. As the cooking time after addition of sugar and soy sauce increased, the degree of browning, saltiness and hardness of kongjaban increased markedly. The amount of sugar and soy sauce did not make a distinct difference in its physical properties whereas its hardness increased slightly with increasing sugar amount. According to the sensory evaluation, the color, hardness and saltiness of kongjaban significantly increased with increasing cooking time. Color, hardness and sweetness increased as the amount of sugar increased whereas the amount of soy sauce did not affect the sensory characteristics except for saltiness.

• Journal of Environmental Science International
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• v.18 no.5
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• pp.489-499
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• 2009

In an effort to examine the Regional Atmospheric Modeling System (RAMS ver. 4.3) to the initial meteorological input data, detailed observational data of NOAA satellite SST (Sea Surface Temperature) was employed. The NOAA satellite SST which is currently provided daily as a seven-day mean value with resolution of 0.1 $^{\circ}$ grid spacing was used instead of the climatologically derived monthly mean SST using in RAMS. In addition, the RAMS SST data must be changed new one because it was constructed in 1993. For more realistic initial meteorological fields, the NOAA satellite SST was incorporated into the RAMS-preprocess package named ISentropic Analysis package (ISAN). When the NOAA SST data was imposed to the initial condition of prognostic RAMS model, the resultant performance of near surface atmospheric fields was discussed and compared with that of default option of SST. We got the good results that the new SST data was made in a standard RAMS format and showed the detailed variation of SST. As the modeling grid became smaller, the SST differences of the NOAA SST run and the RAMS SST43 (default) run in diurnal variation were very minor but this research can apply to further study for the realistic SST situation and the development in predicting regional atmospheric field which imply the regional circulation due to differential surface heating between sea and land or climatological phenomenon.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.33-41
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• 1994

It is well known that the position and the shape of the S/L interface affect the qualities of the single crystal in the growth process. Thus the information of the temperature profile in the growth system is very important. In this study, we developed the program to predict the temperature profile from the setting values of the heating blocks in VGF(vertical gradient freezing) single crystal growth system. With this program, we studied the effects of the materials and the sizes of support rod, the materials of the crucible on the S/L interface shape. The larger radius and/or smaller thermal diffusivity support rod was, the flatter the S/L interface was. When the thermal conductivity of crucible was isotropic, the S/L interface was more concave downward to the solid phase in proportional to the increase of thermal diffusivity of the crucible. By the comparison of the S/L interface shape between PBN crucible and quartz crucible for the same condition, the effect of anisotropy of thermal conductivity of crucible showed different trends with respect to the position of the S/L interface.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.1
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• pp.51-59
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• 2006

The study is diagnosis about fatigue failure phenomenon of heating coil spring (sup9) and heat treatment method that is used to crusher. Because more than 80~90% of damage announcement of breakdown of machine and construction is been caused in fatigue present state, fatigue failure became important leading person at design. Calculated design load is imposed repeatedly that fatigue breakdown is safe. Is phenomenon that change load is imposed in the construction continuously. Used coil spring applies heat 30minute by Quenching temperature $860^{\circ}C$ if see manufacturing process and temperature of gasoline of $50^{\circ}C$ keep after quench that know tempering a $460^{\circ}C$ 90minute a product be. If doto apply heat $950^{\circ}C$ material at rolling process historically before quenching, austenite formation clay pipe being done AGS(Austenite Grain Size) by 2.5~4 become. Apply heat quenching 30minute by $820^{\circ}C$ by improvement method and after quench that keep $50^{\circ}C$ in oil tempering if do $450^{\circ}C$, 90minute spring ideal formation sorbite formation of the river form and condition that satisfy most more than AGS 7 appeared. Also, we can secure authoritativeness through MT since shot peening processing.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.118-123
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• 1987

In relation to the dust detonatians which have imposed severe damages on the industry, the ignitability of various dusts has been investigated on a horizontal shock tube in this study. By using a newly designed air injector, very well-distributed clouds could be obtained. The proper reflected shock conditions have been generated by placing a reflector 1.5cm behind the air injector, which reflected the incident shock wave. The incident shock waves in the range of Mach number 2.8-3.3 created the postreflected shock temperature of 1200-1600K. Experimentally the ignition delay was defined as the time interval between the arrival of a reflected shock wave at dusts and the detection of visible light. Measured ignition delays of dusts investigated were located lower than 1msec under the above conditions. These values are one-order higher than those in the incident shock wave condition. In this type of ignitiion process the following three processes are considered to play important roles; heating of a particle, generation of volatile gas by endothermic devolatilization process, and its diffusion from the particle surface and the formation of stoichiometric mixture with oxidizer.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.115-123
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• 2010

Cool-down performance after soaking is important because it affects passenger's thermal comfort. The cooling capacity of HVAC system determines initial cool down performance in most cases, the performance is also affected by location, and shape of panel vent, indoor seat arrangement. Therefore, optimal indoor designs are required in developing a new car. In this paper, initial cool down performance is predicted by CFD(computational fluid dynamics) analysis. Experimental time-averaging temperature data are used as inlet boundary condition. For more reliable analysis, real vehicle model and human FE model are used in grid generation procedure. Thermal and aerodynamic characteristics on re-circulation cool vent mode are investigated using CFX 12.0. Thermal comfort represented by PMV(predicted mean vote) is evaluated using acquired numerical data. Temperature and velocity fields show that flow in passenger's compartment after soaking is considerably unstable at the view point of thermodynamics. Volume-averaged temperature is decreased exponentially during overall cool down process. However, temperature monitored at different 16 spots in CFX-Solver shows local variation in head, chest, knee, foot. The cooling speed at the head and chest nearby panel vent are relatively faster than at the knee and foot. Horizontal temperature contour shows asymmetric distribution because of the location of exhaust vent. By evaluating the passenger's thermal comfort, slowest cooling region is found at the driver's seat.