• Transactions of the Korean Society of Mechanical Engineers
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• 제16권1호
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• pp.180-188
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• 1992

By means of the compatibility according to solving environmental pollution and energy problem due to the emissions of NOx and smoke from diesel engine this paper experimentally inspected the effect of using emulsified fuel, gas oil-water, for combustion characteristic, that is combustion pressure, pressure rise rate, heat generating rate, the period of ignition delay and specific fuel consumption, and CO, HC, NOx concentration and smoke density. When using emulsified fuel, as a water addition rate was increased, combustion pressure, pressure rise rate and heat generating rate was increased, the period of ignition delay was lengthening, the specific fuel consumption was some what increased in contrast to diesel fuel in low load, but deceased in high load region. And NOx concentration was decreased, CO concentration was increased in low load, but decreased in high load region, HC concentration was increased in contrast to diesel fuel in all region.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제3권5호
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• pp.337-349
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• 1991

Heat and mass transfer rates to spray water droplets for spray transients in a high pressure vessel have been predicted by two different droplet models: the complete mixing model and the non-mixing model. In this process, the ambient fluid surrounding the droplets is a real-gas mixture composed of saturated steam and noncondensable hydrogen gas at high pressure. The physical properties of the mixture are estimated by applying the concept of compressibility factor and using appropriate correlations. A computer program, DROPHMT, to calculate the heat and mass transfer rates for two different droplet models has been developed. As an illustrative application of the computer program to engineering practices, heat and mass transfer rates to spray water droplets for spray transients in a Pressurized Water Reactor (PWR) pressurizer have been calculated, and the typical results have been provided.

• Proceedings of the KSME Conference
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• 대한기계학회 2003년도 추계학술대회
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• pp.700-705
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• 2003

The general cooling tower is a device for making a cooling water in refrigerant condensers or industrial process heat exchangers. The present cooling tower have defects with noises, complicated structure and environmental problems. In this paper, we constituted a new water cooling system by using a evaporating latent heat in an enclosed tank, and this system is consisted of an enclosed vacuum tank and water driving ejector system. Several experimental cases were carried out for improvement methods of high vacuum pressure and water cooling characteristics. The ejector performance was tested in case of water temperature variations that flows in the ejector. Based on the vacuum pressure by water driving ejector, the water cooling characteristics were investigated for the vaporized air condensing effects.

• Journal of the Korea Convergence Society
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• 제10권1호
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• pp.149-154
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• 2019

High pressure valve tester used in industrial fields precise measurement gives inconvenience in precise measurement due to manually regulated pressures. In order to improve this inconvenience, the high pressure valve tester was designed by using CATIA and structural analysis of the designed high pressure valve tester was conducted and water leaking, total deformation, strain and stress were obtained by applying ANSYS. These results will be provided to develop new concepts of high pressure valve tester as initial data.

• Preventive Nutrition and Food Science
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• 제22권2호
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• pp.131-137
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• 2017

Maximum production of isoquercetin and quercetin simultaneously from rutin by subcritical water hydrolysis (SWH) was optimized using the response surface methodology. Hydrolysis parameters such as temperature, time, and $CO_2$ pressure were selected as independent variables, and isoquercetin and quercetin yields were selected as dependent variables. The regression models of the yield of isoquercetin and quercetin were valid due to the high F-value and low P-value. Furthermore, the high regression coefficient indicated that the polynomial model equation provides a good approximation of experimental results. In maximum production of isoquercetin from rutin, the hydrolysis temperature was the major factor, and the temperature or time can be lower if the $CO_2$ pressure was increased high enough, thereby preventing the degradation of isoquercetin into quercetin. The yield of quercetin was considerably influenced by temperature instead of time and $CO_2$ pressure. The optimal condition for maximum production of isoquercetin and quercetin simultaneously was temperature of $171.4^{\circ}C$, time of 10.0 min, and $CO_2$ pressure of 11.0 MPa, where the predicted maximum yields of isoquercetin and quercetin were 13.7% and 53.3%, respectively. Hydrolysis temperature, time, and $CO_2$ pressure for maximum production of isoquercetin were lower than those of quercetin. Thermal degradation products such as protocatechuic acid and 2,5-dihydroxyacetophenone were observed due to pyrolysis at high temperature. It was concluded that rutin can be easily converted into isoquercetin and quercetin by SWH under $CO_2$ pressure, and this result can be applied for SWH of rutin-rich foodstuffs.

• Journal of Korea Water Resources Association
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• 제52권5호
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• pp.373-380
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• 2019

In this study, the optimum pump operation technique is suggested to decrease the damage rate of water distribution system. Pump operation system was developed to achieve the effective pump operation. Pressure sensors which can communicate with pumps are installed at the end of water distribution system. Pump operation system can control the pressure of water pump according to data sent from the pressure sensors. Therefore, water distribution system can reduce the pressure and maintain enough pressure which can supply the demand of water users. For proving effectiveness of new system, reliability model was introduced to compare the results of damage rates between the maintaining high pressure and selective pressure in water pump. Unsteady analysis was conducted with several scenarios. And the results were used to calculate the probability of pipe breakage. From the results, it was found that new pump operation system can reduce the energy usage and probability of pipe breakage by applying to pumps.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.719-722
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• 2005

The watertightness of concrete is judged by the depth of penetration of water forced in under pressure with the mechanism of flow of seepage water examined theoretically and experimentally. As a result, it is found that in the case of low water pressure approximately 0.15Mpa or less, the flow is Darcy seepage flow, the same as flow in an ordinary sand stratum, whereas in the case of high water pressure, the flow is diffused seepage flow accompanied by internal deformation of concrete. It is suggested that the watertightness of concrete be evaluated by seepage coefficient in the case of the former and diffusion coefficient in the case of the latter.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제18권11호
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• pp.83-88
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• 2019

In this study, the high-temperature high-pressure vessel was successfully manufactured, which can be used to store pressurized air and to increase the temperature for the mix performance test of high-temperature high-pressure air with coolant (e.g., water). In this research, static structure analysis and transient thermal analysis were performed using the commercial software Midas NFX 2015 R1. Based on the results, the optimized pressure vessel design was carried out. As a result of the optimized design, the minimum stress and minimum weight were found at 120 mm of the vessel thickness, and the optimized pressure vessel was verified. Finally, through manufacture and performance test (e.g., the non-destructive inspection and hydraulic pressure test), the reliability and safety were validated for the designed pressure vessel.

• Food Science of Animal Resources
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• 제26권4호
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• pp.464-470
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• 2006

This study was carried out to investigate the effect of various high pressure freezing treatments on the physical properties of pork To compare the effect of freezing on meat quality, atmospheric freezing (AF), pressure and freezing (PF), pressure shift freezing (USF) and pressure assisted freezing (PAF) were conducted at pressure of 100 MPa. Water binding properties, shear force and colour were measured as physical properties of pork PAF showed shorter phase transition time than PSF. Although significant increase (p<0.05) in water binding properties was found only at PAF, meat frozen under hydrostatic pressure environment showed improved water binding properties. However, all high pressure freezing treatment caused significantly increased shear force (p<0.05), especially at PF treatment. In color, all high pressure freezing treatments showed significantly higher color parameters (p<0.05) than AF, whilst no significant differences among high pressure freezing treatments were found (p>0.05). Therefore the result indicated that applied hydrostatic pressure improved functional properties of pork with increasing freezing rate and PAF had more potential benefit than PSF at mild pressure range.

• Journal of the Korean Society of Safety
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• 제25권6호
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• pp.109-114
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• 2010

Water mist fire suppression system is environmental system and needs a flange pump to jet water. In this research, high pressure Nitrogen cylinder is used as a pressurizing source instead of flange pump, and also we tried to find the possibility of using compressed Nitrogen as a fire suppression agent. As a result, it was possible to design water mist fire suppression system with Nitrogen cylinder and suppress oil fire effectively. With DK1.58 nozzle, the optimum Nitrogen pressure was 80bar and the pressure was stable during water mist spray. However, jet of Nitrogen was not effective fire suppression agent when it was dually used with water mist because water mist has blown away, and it is efficient way to use compressed Nitrogen as a pressurizing source only.