• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.9
• /
• pp.1263-1271
• /
• 2001

An experimental study is carried out for an aluminum foam heat sink attached to an isolated heat source to evaluate high potential of aluminum foam as a heat sink with impinging jets. The effects of the pore density and the height of the aluminum foam heat sink, the jet Reynolds number, and the nozzle diameter are delineated in comparison with a conventional pin type heat sink. It is found that the aluminum foam with small pores is inefficient for the heat transfer enhancement due to the large flow friction at the given porosity. In the parameter ranges of the present study, the change in the nozzle diameter shows no significant effects on the surface temperature of the aluminum foam heat sink at a given Reynolds number. The heat transfer enhancement is strongly dependent on the jet Reynolds number and shows a maximum value at a moderate Reynolds number.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.12
• /
• pp.825-832
• /
• 2008

The ice slurry maker which can produce the ice slurry well for the ice particle in-flowing condition was revised. We removed the stagnant region at the top of the ice slurry maker, and IPF 40% could be realized. The IPF controller with 6 mm diameter holes at the bottom was designed. But the IPF controller with only 6 mm diameter holes could not control IPF in a pipe. This is because the ice particles at ice slurry flow exist homogeneously not only at the upper part but also at the bottom part. We changed the hole size of IPF controller surface using fine meshes and then, IPF in a pipe was increased by 70% when the hole size was $80{\mu}m$ and less.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.18 no.10
• /
• pp.776-782
• /
• 2006

A new district cooling system using ice slurry for the uncertain cooling load of the future is presented. The chilled water produced by the absorption chillers is used for the base cooling load. The temperature of the chilled water is reduced by mixing of ice slurry depending on increasing of the cooling load. Finally, IF of the ice slurry is increased up to 10% at the peak load. The transporting mass flow rate is decreased down to 44.7%, and the diameter of the main pipe is decreased down to 66.7%, but the diameter of the branched pipe is designed as the same size of the chilled water.

• Childhood Kidney Diseases
• /
• v.6 no.1
• /
• pp.68-74
• /
• 2002

Purpose: Suprapubic bladder aspiration(SBA) of urine is the most reliable method to obtain urine avoiding contamination in non-toilet trained infants. Ultrasonography is a useful tool for guiding the anatomic location as well as for direct visualization during procedure. We evaluated the success rate and complication of ultrasound(US) assisted SBA Methods. Sixty infants who visited Ewha Womans University Mokdong Hospital, with suspected urinary tract infection were randomly divided into the US assisted (n=32) and blind SBA(control, n=28) group. In US assisted SBA group, the anteroposterior(AP), transverse, and sagittal diameters and the volume of the bladder were measured. In the blind SBA group, urine was blindly aspirated when the urinary bladder was palpated at the suprapubic area. The rate of successful urine aspiration, the number of attempts until successful aspiration, aspirated urine volume were compared between the two groups. Results: The success rate was $100\%$(32/32) in the US assisted group, which was significantly higher than $85.7\%$(24/28) of the control group (P<0.05). The aspirated urine volume in the US assisted group was $7.4{\pm}3.7\;mL$, which was significantly higher than $4.5{\pm}3.4\;mL$ of the control group (P<0.05), The diameters and volume of bladder in successful aspiration were $2.1{\pm}0.7\;cm$ in AP diameter, $3.1{\pm}0.6\;cm$ in transverse diameter, $4.2{\pm}1.0\;cm$ in sagittal diameter and $15.2{\pm}10.4\;mL$ in volume, which were significantly higher than those ($1.7{\pm}0.3\;cm,\;1.7{\pm}0.3\;cm,\;1.8{\pm}0.7\;cm,\;2.4{\pm]0.6\;cm,\;3.9{\pm}2.5$) of the control group (P<0.05) The correlations between the AP(r=0.78), transverse (r=0.72), sagittal(r=0.91) diameter and bladder volume were significant (P<0.05). SBA was $100\%$ successful in the AP diameter >3 cm, transverse diameter >4 cm, depth >4 cm and bladder volume >5 mL. Conclusion: US assistance can significantly improve the success rate of SBA in infant with suspected urinary tract infection. (J Korean Soc Pediatr Nephrol 2002 ; 6 : 68-74)

• Tuberculosis and Respiratory Diseases
• /
• v.79 no.4
• /
• pp.201-206
• /
• 2016

Active tuberculosis (TB) has a greater burden of TB bacilli than latent TB and acts as an infection source for contacts. Latent tuberculosis infection (LTBI) is the state in which humans are infected with Mycobacterium tuberculosis without any clinical symptoms, radiological abnormality, or microbiological evidence. TB is transmissible by respiratory droplet nucleus of $1-5{\mu}m$ in diameter, containing 1-10 TB bacilli. TB transmission is affected by the strength of the infectious source, infectiousness of TB bacilli, immunoresistance of the host, environmental stresses, and biosocial factors. Infection controls to reduce TB transmission consist of managerial activities, administrative control, engineering control, environmental control, and personal protective equipment provision. However, diagnosis and treatment for LTBI as a national TB control program is an important strategy on the precondition that active TB is not missed. Therefore, more concrete evidences for LTBI management based on clinical and public perspectives are needed.

• Journal of the Korean Society for Railway
• /
• v.8 no.4
• /
• pp.330-336
• /
• 2005

This paper presents a development of the control and the virtual reality visual system for a tilting train simulator. The user of the tilting train simulator is able to set up the environmental and operating conditions through the user interface provided by the control system. In the control system, an arbitrary track which has user-defined curve radius, length and direction can be generated. The virtual reality visual system provides an artificial environment that is composed of several facilities such as station, platform, track, bridge, tunnel and signaling system. In order to maximize the reality, all of the 3D modeling were based on the real photographs taken in the Jungang line. A dome screen with 1600mm diameter was used to maximize the view angle. The hemispherical screen can ensure the view angle of the 170 degrees of vertical direction and 135 degrees of lateral direction.

• Proceedings of the KIPE Conference
• /
• 2011.07a
• /
• pp.294-295
• /
• 2011

This paper presents the design and development of Web control algorithm of continuous process control system using vector inverter. Web algorithm used tension control without the tension sensor, and it is to calculate the diameter of Web materials with maintain Web tension. The performance of Web control in this paper is verified by experiment.

• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.671-674
• /
• 2002

Pressure compensating temperature control valve(TCV) is one of the important control devices, which is used to maintain the constant temperature of working fluid in power and chemical plants. The ratio of cylinder hole diameters of inlet and outlet is the main design parameters of TCV. So this needs to be investigated to improve the function of control of temperature and void fraction. In this study, numerical analysis is carried out with various ratios of cylinder hole diameters of the inlet and outlet in the TCV. Especial1y, the distribution of the static pressure Is investigated to calculate the new coefficient($C_{\upsilon}$) and resistance coefficient(K). The governing equations are derived from making using of three-dimensional Naver-Stokes equations with standard $k-{\varepsilon}$ turbulence model and SIMPLE algorithm. Using a commercial code, PHOENICS, pressure and flow fields in TCV are calculated with different inlet and outlet diameters of the cylinder hole for cold and hot water passages.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.314-315
• /
• 2010

This paper presents the design and development of Web control algorithm of continuous process control system using torque controlled vector inverter. Web algorithm used tension control with the tension sensor, and it is to calculate diameter of motor speed with maintain Web tension. The performance of Web control in this paper is verified by experiment.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.9
• /
• pp.26-33
• /
• 2010

A multi-MW wind turbine is a huge mechanical structure, of which the rotor diameter is more or less than 100 m. Rotor blades experience unsymmetric mechanical loads caused by the interaction of incoming wind with the tower and wind shear effect. These mechanical loads are transferred to the entire structure of the wind turbine and are known as the major reasons for shortening the life span of the wind turbine. Therefore, as the size of wind turbine gets bigger, the mitigation of mechanical loads becomes more important issue in wind turbine control system design. In this paper, a concept of an individual pitch control(IPC), which minimizes the mechanical loads of rotor blades, is introduced, and simulation results using IPC are discussed.