• Journal of Animal Environmental Science
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• v.3 no.2
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• pp.77-85
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• 1997

Recently, local swine producers are rapidly adopting the indoor production system which developed in foreign countries. However, this imported system is reported as not functioning properly because of different climate conditions. The objective of this project was to investigate the environment characteristics of a windowless delivery swine building. The parameters studied were the heating and cooling loads, the daily changes of indoor temperature and relative humidity, the horizontal and the vertical distributions of indoor temperature, and the effect of mist cooling on indoor temperature. From this study, the following are founded : 1. The maximum cooling and heating loads were - 317.0kcal/㎡$.$h and 336.5kal/㎡$.$h in summer and in winter. The large loads seems to be on account of inappropriate operations of ventilating fans. 2. The daily variations of relative humidity in indoor were smaller than those in outside. Those values both in summer and in winter as relative humidities in door was lower than optimum for growing pigs, the additional humidifier might be helpful to increase the relative humidity in indoor. 3. The horizontal distribution of the indoor temperature was found to be uniform in the variation range of 1$^{\circ}C$. 4. The vertical distribution of the indoor temperature was not found to be uniform; the temperature of upper part was higher than that of slot part. 5. Average values of indoor temperature became lower by 3$^{\circ}C$ by mist cooling. But the variation of temperature was found to be larger; The middle part of the room was cooled down, but the corner part of the room was not affected by misting due to uneven nozzle configuration.

• Journal of Embryo Transfer
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• v.27 no.1
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• pp.37-43
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• 2012

This study evaluated a method of sorting X and Y chromosomes based on size using the forward angle light scatter related refractive index (FSC) of a flow cytometer. Hanwoo bulls sperm were separated to X and Y chromosomes by the parameters of FSC or Hoechst 33342 intensity. As a result, using monitor program linked flow cytometry during sorting processing, the purities were $97{\pm}0.57$ or $96{\pm}0.67%$ for the X-fraction and $96{\pm}0.33$ or $97{\pm}1.33%$ for the Y-fraction in the two sperm sorting methods. There were no differences in the X and Y ratios (X and Y %) between the sperm sorting methods based on FSC or DNA content. The proportions of female and male embryos used for in vitro fertilization and development were $66.03{\pm}3.31$ or $69.37{\pm}1.41%$, and $70.56{\pm}2.42$ or $56.11{\pm}3.09%$ when sperm were processed using the sex sorting method by FSC or Hoechst 33342. In conclusion, further study is needed to determine the optimum procedure and improve the nozzle to enhancing sorting accuracy or efficiency. Also, the findings of this study do not negate the possibility that the difference method of sperm sorting cannot use a UV laser beam.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.70-79
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• 2013

The isothermal flow structure and mixing characteristics of a hybrid/dual swirl jet combustor for micro-gas turbine (MGT) were numerically investigated. Location of pilot burner, swirl angle and direction were varied as main parameters with the identical thermal load. As a result, the variations in location of pilot nozzle, swirl angle and direction resulted in the significant change in turbulent flow field near burner exit, in particular, center toroidal recirculation zone (CTRZ) as well as turbulent intensity, and thus the flame stability and emission performance might be significantly changed. With the comparison of experimental results, the case of swirl angle $45^{\circ}$ and co-swirl flow including optimum location of pilot burner were chosen in terms of the flame stability and emissions for the development of hybrid/dual swirl jet combustor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.9
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• pp.1317-1324
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• 1998

In general, DI gasoline engine has the advantages of higher power output, higher thermal efficiency, higher EGR tolerance and lower emissions due to the operation characteristics of increased volumetric efficiency, compression ratio and ultra-lean combustion scheme. In order to apply the concept of stratified charge into direct injection gasoline engine, some kinds of methodologies have been adapted in various papers. In this study, a reflector was adapted around the injector nozzle to apply the concept of stratified charge combustion which leads the air-fuel mixture to be rich near spark plug. Therefore, the mixture near the spark plug is locally rich to ignite while the lean mixture is wholly introduced into the combustion chamber. The characteristics of combustion is analyzed with the variations of fuel injection pressure and load in a stratified -charge direct injection single cylinder gasoline engine. The obtained results are summarized as follows ; 1. The MBT spark timing approached to TDC with the increase of load on account of the increase of evaporation energy, but has little relation with fuel injection pressure. 2. The stratification effects are apparent with the increase of injection pressure. It is considered by the development of secondary diffusive combustion and the increase of heat release of same region, but proceed rapidly than diesel engine. Especially, in the case of high pressure injection (l70bar) and high load (3.0kgf m), the diffusive combustion parts are developed excessively and results in the decrease of peak pressure than in the case of middle load. 3. The index of engine stability, COVimep value, is drastically decreased with the increase of load. 4. To get better performance of DI gasoline engine development, staged optimizaion must be needed such as injection pressure, reflector, intake swirl, injection timing, chamber shape, ignition system and so on. In this study, the I50bar injection pressure is appeared as the optimum.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.11-18
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• 1998

This study describes sea trial tests for a waterjet propulsion system attached in the hybrid super high speed cargo ship named "Narae". A measuring technique of jet velocity, gross thrust and impeller torque for the waterjet system is explained. From the measured data in sea trial test, performance of the waterjet propulsion system is analyzed and compared with model test results of a similar waterjet system which was carried out in 1996. The erective horse power estimated from sea trial tests shows a good agreement with resistance test results of the model ship. The optimum rising height is estimated as 0.75 m, and the overall efficiency of the waterjet system is predicted as 0.315 at 15 knots. Useful data such as the pump performance, the jet efficiency, the losses of inlet duct and nozzle were obtained. Test results show a similar behavior to the model test results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.299-304
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• 2008

Starting characteristics of the axi-symmetric second throat exhaust diffuser (STED) with zero-secondary flows are numerically investigated. Renolds-Average Navier-Stokes equations with a standard ${\kappa}-{\varepsilon}$ turbulence model incorporated with enhanced wall treatment are solved to simulate the diffusing evolutions of the nozzle plume. Minimum (optimum) starting pressure difference of 20$\sim$25% between 1-D theory and the measured data validated from previous results[5] is also applied to predict the range of an effective diffuser expansion ratio (Ad/At) in this system.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.44-54
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• 2018

In a spray experiment using a venturi mounted on a lean premixed LPP injector, droplets appear to have non-uniform distributions. To solve this problem, the exit angle of the venturi was changed to form a dump surface on the nozzle neck. The dump surface improved the atomization performance and minimized droplet loss while forming recirculation zone in the venturi exit. In order to solve the non-uniform spray of the injector, the flow characteristics inside the venturi and SMD of the spray are compared. Finally, an optimum venturi shape is selected to minimize the spray loss and improve the spray performance.

• Plant Journal
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• v.18 no.3
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• pp.52-61
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• 2022

This study tested the effect of de-NOx Facility operating condition on Nox emisiion in a 125 MW wood pellet power plant in Yeongdong Eco Power Plant Unit 1, which is in operation. As SNCR urea flow rate increased, NOx emission gradually decreased, but ammonia slip after SCR increased. The boiler under test has a structure that is unfavorable to SNCR operation due to the high internal temperature, and the optimum location of the nozzle will be required. SCR dilution air temperature change did not affect the amount of NOx generated. Increasing SCR ammonia flow reduced the NOx emission at SCR outlet and also increased the NOx removal efficiency. However, the ammonia flow rate of 111 kg/h, which does not exceed the ammonia slip its own reference limit, is estimated to be the maximum operating standard. The increase in SCR mixer pressure reduced NOx emission and the removal efficiency was also measured to be the most effective variable to inhibit NOx production.

• Textile Coloration and Finishing
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• v.34 no.3
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• pp.185-196
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• 2022

In this study, carbon fiber and coated glass fiber are applied to warp and weft fiber in order to reduce the amount of carbon fiber used in carbon fiber fabrics, which are often used for reinforcement of building structures. A low-cost thermoplastic resin was coated on glass fibers to prepare a shape-stabilizing glass fiber. A unidirectional carbon fiber sheet was manufactured using the prepared coated glass fiber and carbon fiber. In order to identify whether it can be used for reinforcing architectural and civil structures, it was attached to a concrete specimen and its mechanical properties were analyzed. The optimum manufacturing conditions for the coated glass fiber were 0.3 mm in diameter of the coating nozzle, the coating temperature was 190 ℃, and the coating speed was 0.3 m/s. 14 mm was optimal for the weft spacing of the coated glass fiber. The flexural strength of the concrete reinforced with the manufactured unidirectional carbon fiber sheet was slightly lower than that of the concrete reinforced with carbon fiber fabric, but it was confirmed that the reinforcement effect was better when the amount of carbon fiber was considered.

• Journal of the Korean Applied Science and Technology
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• v.30 no.2
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• pp.320-332
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• 2013

The feed air to MSW incinerator influences on the residence time of combustion gas, removal of unburnt ash and exiting gas temperature. Thus the secondary air volume could present sufficient residence time which can maintain the exiting temperature over $850^{\circ}C$. The secondary air also relates directly with the turbulence in the inside of combustion chamber, which finally provide the stable combustion condition. The present study designed a modern incinerator for a field scale, and evaluation of the potential amount of primary air based on the daily combustible quantity. From the evaluated primary air volume, the secondary air flow rate could be estimated, and its dynamic behavior was verified. In addition, the obtained air volume enables to find an optimum operation condition of the combustion. As a result of the CFD simulation, the air ratio 75 : 25 between primary and secondary air amount was optimum ratio than design criteria 72 : 28. And the flow velocity ratio of front-back of secondary air jet nozzle was found excellent at 1 : 3. In addition, the result of applied to the plant, the removal efficiency of NOx and CO generation would concentration of CO.