• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.19 no.4
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• pp.251-258
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• 2016

Purpose: This study aimed to evaluate the utility of acanthosis nigricans (AN) severity as an index for predicting insulin resistance in obese children. Methods: The subjects comprised 74 obese pediatric patients who attended the Department of Pediatrics at Chosun University Hospital between January 2013 and March 2016. Waist circumference; body mass index; blood pressure; fasting glucose and fasting insulin levels; lipid profile; aspartate transaminase, alanine transaminase, glycated hemoglobin, C-peptide, and uric acid levels; and homeostatic model assessment insulin resistance (HOMA-IR) and quantitative insulin check sensitivity index (QUICKI) scores were compared between subjects with AN and those without AN. Receiver operating characteristic curves were used to investigate the utility of the AN score in predicting insulin resistance. HOMA-IR and QUICKI were compared according to AN severity. Results: The With AN group had higher fasting insulin levels ($24.1{\pm}21.0\;mU/L$ vs. $9.8{\pm}3.6\;mU/L$, p<0.001) and HOMA-IR score ($5.74{\pm}4.71$ vs. $2.14{\pm}0.86$, p<0.001) than the Without AN group. The AN score used to predict insulin resistance was 3 points or more (sensitivity 56.8%, specificity 83.9%). HOMA-IR scores increased with AN severity, from the Without AN group (mean, 2.15; 95% confidence interval [CI], 1.72-2.57) to the Mild AN (mean, 4.15; 95% CI, 3.04-5.25) and Severe AN groups (mean, 7.22; 95% CI, 5.08-9.35; p<0.001). Conclusion: Insulin resistance worsens with increasing AN severity, and patients with Severe AN (AN score ${\geq}3$) are at increased risk of insulin resistance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.797-806
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• 2008

In a double-passage cascade apparatus, only two blades are installed in order to increase the accuracy of experimental result by applying bigger blade than the size of multi-blades on the same apparatus. However, this causes difficulties to make correct periodic condition. In this study, sidewalls are designed to meet periodic condition without removing the operating fluid or adjusting tail boards. Surface Mach number on the blade surface is applied to a responsible variable, and 12 design variables which are related with sidewall profile control are selected. A gradient-based optimization is adopted for wall design and CFX-11 is used for the internal flow computation. The computed result shows that it could obtain the same flow structure by modifying only the sidewalls of the double-passage cascade apparatus.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.12
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• pp.1143-1150
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• 2007

The fuel transfer characteristics of the jet pump between fuel tanks, which is applied in the smart UAV fuel supply system, were experimentally investigated. The operating conditions of the jet pump were setup to meet the engine requirement according to mission profile, and the jet pump performance was evaluated at those conditions. The pressure ratio and the efficiency of the jet pump were measured with the variation of flow ratio. In addition, the area ratio was taken into the consideration to examine the effect on the jet pump performance. From the evaluation results, the jet pump met the fundamental requirement to transfer fuel with the flow ratio of 2.23. In the case of the jet pump that is focused on the fuel transfer quantity rather than its efficiency, the flow ratio would be adjusted through the variation of area ratio of the jet pump within the permitted limit of pressure ratio.

• Membrane and Water Treatment
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• v.9 no.1
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• pp.43-51
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• 2018

Hollow fiber (HF) membranes are gaining wide interest over flat membranes due to their compaction and high area to surface volume ratio. This work addresses the fabrication of HF from polysulfone (PS) and polyethersulfone (PES) using N-methylpyrrolidone (NMP) as solvent in addition to other additives to achieve desired characteristics. The semi-pilot spinning system includes jacketed vessel, four spinneret block, coagulation and washing baths in addition to dryer and winder. Different parameters affecting dry-wet spinning phase inversion process were investigated. Dope compositions of PES, NMP and polyvinyl pyrrolidone (PVP) of varying molecular weights as additive were addressed. Some critical parameters of importance were also investigated. Those include dope flow rate, air gap, coagulation & washing baths and drying temperatures. The measured dope viscosity was in the range from 1.7 to 36.5 Pa.s. Air gap distance was adjusted from 20 to 45 cm and coagulation bath temperature from 20 to $46^{\circ}C$. The HF membranes were characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and mechanical properties. Results indicated prevalence of finger like structure and average surface roughness from about 29 to 78.3 nm. Profile of stress strain characteristics revealed suitability of the fibers for downstream interventions for fabrication of thin film composite membrane. Different empirical correlations were formulated which enable deeper understanding of the interaction of the above mentioned variables. Data of pure water permeability (PWP) confirmed that the fabricated samples fall within the microfiltration (MF)-ultrafiltration (UF) range of membrane separation.

• Journal of Biomedical Engineering Research
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• v.29 no.4
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• pp.323-328
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• 2008

A patient with respiratory disorders such as a sleep apnea is increasing as the obese patient increase on the modern society. Positive Airway Pressure (PAP) devices are used in curing patient with respiratory disorders and turn out to be efficacious for patients of 75%. However, these devices are required for evaluating their performance to improve their performance by the mechanical breathing simulator. Recently, the mechanical breathing simulator was studied by the real time feedback control. However, the mechanical breathing simulator by an open loop control was specially required in order to analyze the effect of flow rate and pressure after operating the breathing auxiliary devices. Therefore the aims of this study were to make the mechanical breathing simulator by a piston motion and a valve function from the characteristic test of valve and motor, and to duplicate the flow rate and pressure profiles of some breathing patterns: normal and three disorder patterns. The mechanical simulator is composed cylinder, valve, ball screw and the motor. Also, the characteristic test of the motor and the valve were accomplished in order to define the relationship between the characteristics of simulator and the breathing profiles. Then, the flow rate and pressure profile of human breathing patterns were duplicated by the control of motor and valve. The result showed that the simulator reasonably duplicated the characteristics of human patterns: normal, obstructive sleep apnea (OSA), mild hypopnea with snore and mouth expiration patterns. However, we need to improve this simulator in detail and to validate this method for other patterns.

• The Journal of the Korea Contents Association
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• v.18 no.9
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• pp.569-583
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• 2018

In this study, we suggested a data structure for the management of human libraries based on the analysis of the significant components for systematically managing and operating the human library service. At first, we proposed the components of human library metadata set which are 'Human Resource', 'Human Resource', 'Librarian', 'Volunteer', and 'User'. And this study verified the meta concepts of metadata set such as 'Human Library', 'Human Book' and 'User', developed the metadata set for human library using the meta concepts. To check the validity of the metadata set and to improve its usability, we created and published a XML document including the metadata structure and link between the meta concepts. In conclusion, this study provided the possibility that the library could develop the service recommended human book to user through user profile.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.764-769
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• 2001

Recently, according to increase in the requirement of electric power, a thermoelectric power plant equipped with pulverized coal combustion system is highly valued, because coal has abundant deposits and a low price compared with others. For efficient use of coal fuel, most of plant makers are studying to improve combustion performance and flame stability, and reduce pollutant emission. One of these studies is how to control the profile of particle injection and velocity dependant on coal nozzle. Basically, a mixed flow of gas and particle in coal nozzle is required to have appropriate injection and concentration distribution at exit to achieve flame stability and low pollutant, but it is very difficult to obtain that without help of a coal separating device within nozzle. In this study, each distribution of air and coal flow rate is measured for the coal nozzle with coal separator developed by us. The coal concentration at exit is various according to inlet swirl values and positions of coal separator. Also pressure drop is measured for various operating conditions of this nozzle. From these results, we can find the separation characteristic of new developed coal separator, and select proper operation range of coal nozzle. When this coal nozzle is applied to actual plant, these investigations will be very useful to confirm the shape of coal separator to have efficient particle injection.

• Korean Journal of Optics and Photonics
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• v.20 no.2
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• pp.71-75
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• 2009

A compact electric field probe sensor incorporating two different electro-optic materials of $LiNbO_3$ and GaAs was proposed and fabricated, and it was used to measure the strength of the horizontal and vertical fields generated by a microstrip ring-resonator filter. The sensitivities of the sensors in $LiNbO_3$ and GaAs were $9.315{\mu}V/\sqrt{Hz}$ and ${\sim}49.346{\mu}V/\sqrt{Hz}$ respectively, and their signal to noise ratios were approximately ${\sim}50\;dB$ and ${\sim}40\;dB$ respectively. And the operating frequency range was up to ${\sim}1.2\;GHz$. The electric field profile for the test circuit was scanned and found to be in good agreement with that obtained by using the HFSS simulation.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.200-207
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• 1993

A methanol reformer was designed and fabricated using a CuO-ZnO low temperature shift catalyst, and its operation characteristics have been studied for the phosphoric acid fuel cell (PAFC) power generation system. The type of reactor was annular Methanol was consumed both for heating and for reforming fuel. Contents of carbon monoxide produced from the reformer increased as the reaction temperatures increased, but decreased as the mole ratios of water to methanol(H$_2$O/CH$_3$OH) increased. At steady state operating conditional, temperature profile of the catalytic reactor of the reformer was well coincide with the model equation, and it took 50 minutes from start to the rated condition of the reformer. When the system was operated at 4/4 and 1/4 of load, thermal efficiencies of the system were 72.3% and 77%, respectively. When the PAFC system was operated with reformed gas in the range of 62 V-37.6 V and 0-147 A, the trend of I-V curve showed a typical fuel tell characteristic. At steady state condition, the flow rates of reforming and combustion methanol were 88.1 mol/h and 50.1 mol/h, respectively.

• Journal of the Korea Computer Industry Society
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• v.2 no.9
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• pp.1147-1154
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• 2001

In this paper, we make plans for facilities, the 8-VSB DTV transmission system, installed in the near future, based on presently NTSC TV operating it. First of all we estimate transmission power for analog NTSC, digital 8-VSB terrestrial broadcasting and the effective condition of optimal receiving power result from it. It's also to estimate optimal receiving condition by using Longley-Rice's Field Strength calculating method that is to guess a profile between transmitting station and many receiving points. The 8-VSB DTV Propagation aims to high-speed transmission rates of 19.39Mbps datum to enable HDTV(High Definition Television) at NTSC 6MHz bandwidth. First of all, an optimization of field strength between transmission station and receiver must deal with considerable. Because of these reasons, 8-VSB DTV transmission needs effective extension for NTSC TV service coverage. Finally we present the transmitting output that is expected in changing NTSC VHF to DTV UHF for maintaining the transmitting output of NTSC TV that is equal to 8-VSB DTV in service coverage.