• Proceedings of the KSME Conference
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• 2005.11a
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• pp.50.1-50.1
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• 2005

• Journal of KIISE:Information Networking
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• v.32 no.6
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• pp.732-744
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• 2005

Previous works for the AE(Assured Forwarding) service in the Diffserv network have no sufficient consideration on the fairness of bandwidth share based on the target rate and the effect or RTT and UDP. Also Previous works act like Best-effort service in the UPN(under-Provisioned Network) condition. In this paper, in order to solve these problems, we propose the PFDSA(Proportionally Fair Differentiated Service Architecture) composed of tmTRA3CM(tcp-microflow based Target rate and an Aware Three color Marking), um3CM(udp-microflow based Three color Marker), TRBD(Target Rate Based Dropper), and target rate adjusting function. In the results of comparing the performance among existing mechanisms and the PFDSA, the PFDSA was able to mitigate the RTT and UDP effect better than the former. The PFDSA was shown to provide good performance for transmission rates proportional to various target rates in the UPN condition.

• Rapid Communication in Photoscience
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• v.2 no.3
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• pp.68-71
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• 2013

Acetone sensitized photoadditions of isopropanol to (5R)-5-menthyloxy-2-(5H)-furanone were investigated in two different microflow reactor systems. Setup A employed a commercially available glass reactor under a UVB-panel. Setup B utilized a FEP microcapillary wrapped tightly around a Pyrex cylinder with a single UVB fluorescent tube at its center. The reactions under flow conditions were subsequently compared to analogue reactions conducted in a batch chamber reactor. Overall, the microflow systems gave faster conversions and higher isolated yields. The flexible microcapillary setup, however, showed the best performance and promise in terms of future scale-up and reactor optimization.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.2
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• pp.154-159
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• 2004

A new microflow rate controller for medical injection was developed and evaluated. The flow rate was controlled by changing the friction depth as well as the friction length of the micro-channel. A precise micro-fabrication of the micro-channel was requested for an accurate flow control. The friction depth was inversely proportional to the friction length, which gives a linear flow control to the channel length. The channel groove was fabricated with a plastic material. A rubber containing silicone oil was covered over the groove, which satisfies both lubrication and leakage prevention. The flow controller was validated by performing the numerical simulation and experiment. A good agreement was shown between computation and experiment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1923-1930
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• 2004

This paper presents digital microflow controllers(DMFC), where a fluidic digital-to-analog converter(DAC) is used to achieve high-linearity, fine-level flow control for applications to precision biomedical dosing systems. The fluidic DAC, composed of binary-weighted flow resistance, controls the flow-rate based on the ratio of the flow resistance to achieve high-precision flow-rate control. The binary-weighted flow resistance has been specified by a serial or a parallel connection of an identical flow resistor to improve the linearity of the flow-rate control, thereby making the flow-resistance ratio insensitive to the size uncertainty in flow resistors due to micromachining errors. We have designed and fabricated three different types of 4-digit DMFC: Prototype S and P are composed of the serial and the parallel combinations of an identical flow resistor, while Prototype V is based on the width-varied flow resistors. In the experimental study, we perform a static test for DMFC at the forward and backward flow conditions as well as a dynamic tests at pulsating flow conditions. The fabricated DMFC shows the nonlinearity of 5.0% and the flow-rate levels of 16(2$^{N}$) for the digital control of 4(N) valves. Among the 4-digit DMFC fabricated with micromachining errors, Prototypes S and P show 27.2% and 27.6% of the flow-rate deviation measured from Prototype V, respectively; thus verifying that Prototypes S and P are less sensitive to the micromachining error than Prototype V.V.

• Korean Journal of Radiology
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• v.20 no.5
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• pp.759-772
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• 2019

Objective: To investigate the value of ultrasound (US) microflow assessment in distinguishing malignant from benign solid breast masses as well as the association between US parameters and histologic microvessel density (MVD). Materials and Methods: Ninety-eight breast masses (57 benign and 41 malignant) were examined using Superb Microvascular Imaging (SMI) and contrast-enhanced US (CEUS) before biopsy. Two radiologists evaluated the quantitative and qualitative vascular parameters on SMI (vascular index, morphology, distribution, and penetration) and CEUS (time-intensity curve analysis and enhancement characteristics). US parameters were compared between benign and malignant masses and the diagnostic performance was compared between SMI and CEUS. Subgroup analysis was performed according to lesion size. The effect of vascular parameters on downgrading Breast Imaging Reporting and Data System (BI-RADS) category 4A masses was evaluated. The association between histologic MVD and US parameters was analyzed. Results: Malignant masses were associated with a higher vascular index (15.1 ± 7.3 vs. 5.9 ± 5.6), complex vessel morphology (82.9% vs. 42.1%), central vascularity (95.1% vs. 59.6%), penetrating vessels (80.5% vs. 31.6%) on SMI (all, p < 0.001), as well as higher peak intensity (37.1 ± 25.7 vs. 17.0 ± 15.8, p < 0.001), slope (10.6 ± 11.2 vs. 3.9 ± 4.2, p = 0.001), area (1035.7 ± 726.9 vs. 458.2 ± 410.2, p < 0.001), hyperenhancement (95.1% vs. 70.2%, p = 0.005), centripetal enhancement (70.7% vs. 45.6%, p = 0.023), penetrating vessels (65.9% vs. 22.8%, p < 0.001), and perfusion defects (31.7% vs. 3.5%, p < 0.001) on CEUS (p ≤ 0.023). The areas under the receiver operating characteristic curve (AUCs) of SMI and CEUS were 0.853 and 0.841, respectively (p = 0.803). In 19 masses measuring < 10 mm, central vascularity on SMI was associated with malignancy (100% vs. 38.5%, p = 0.018). Considering all benign SMI parameters on the BI-RADS assessment, unnecessary biopsies could be avoided in 12 category 4A masses with improved AUCs (0.500 vs. 0.605, p < 0.001). US vascular parameters associated with malignancy showed higher MVD (p ≤ 0.016). MVD was higher in malignant masses than in benign masses, and malignant masses negative for estrogen receptor or positive for Ki67 had higher MVD (p < 0.05). Conclusion: US microflow assessment using SMI and CEUS is valuable in distinguishing malignant from benign solid breast masses, and US vascular parameters are associated with histologic MVD.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.349-354
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• 2010

Fuel cells have attracted enormous interest as new power sources because the cells can be used to solve the problem of environmental pollution as well as the natural-resource exhaustion problem. In this study, hydrogen-gas flow in microchannels of different shapes was numerically analyzed to improve the efficiency of a microfuel cell. Flow characteristics in six microchannels of different shapes but under identical boundary conditions were simulated. The analysis result shows that the flow characteristics such as velocity, uniformity, and flow rate, greatly depend upon the channel shape. This implies that the efficiency of microfuel cell can be expected to be increased by adopting the optimal configuration of channel shape for hydrogen-gas flow. The experimental results show that power density of a PEMFC with a microflow channel is higher than that of a PEMFC without a microflow channel; however, a durable catalyst is required in MEA.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.1
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• pp.63-72
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• 2012

In livestock industry, damage caused by the epidemic diseases such as Foot-and-Mouth Disease (FMD), Highly-Pathogenic-Avian-Influenza (HPAI) and Porcine-Reproductive-and-Respiratory-Syndrome (PRRS) was very serious. The financial loss incurred from FMD alone which occurred on Nov. 2011 in Korea was estimated at 3 billion won, 23 % of annual livestock industry production. The livestock industry in Korea has greater risk of disease infection because of high density production, etc. Investigating the spread of livestock diseases should consider both direct and indirect contact as well as other various factors including airborne. Airborne infection of livestock disease was first hypothesised in the early 1900s, however, field experimental studies are still limited. Furthermore, no protocol is available in detecting airborne viruses in the field. In this study, effective virus samplers were investigated by comparative analysis of the type of samplers used detect to airborne virus. Laboratory experiments were conducted to compare virus samplers such as Bio-sampler, Dust-sampler, Compact-Cascade-Impactor (CCI) and Microflow in detecting PRRSV. Samples were analyzed by Reverse-Transcription PCR to assess the efficiency of the instrument in detecting the airborne virus. First, samples were classified into five levels according to light intensity of gel images and then the classified results were normalized. In every case, Bio-sampler and Dust-sampler were comparable with each other and have shown to be more effective than CCI and Microflow samplers.

• Membrane Journal
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• v.24 no.1
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• pp.50-62
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• 2014

An asymmetric microfiltration membranes were prepared with polysulfone by an immersion precipitation phase inversion method. Microfiltration membranes were prepared by polysulfone/N-methyl-2-pyrrolidone/polyvinylpyrrolidone/phosphoric acid casting solution and water coagulant. The vapor induced phase inversion method was used to prepare the membranes. The pore size and the morphology were changed by the phosphoric acid additive, the temperature of casting plate and the exposure time at the relative humidity of 74%. The morphology of membranes was investigated by scanning electron microscopy and microflow permporometer. By the addition of the phosphoric acid additive in the casting solution, the morphology of the prepared membranes were changed from a dense sponge structure to a loose asymmetric sponge structure. Due to the addition of catalytic amount of phosphoric acid to NMP casting solution, the mean pore size increased almost $0.2{\mu}m$ and the water flux increased about 3,000 LMH. The temperature of casting plate and exposure time had a apparent effect on the skin layer structure and the pore size and the porosity of the membrane.

• Membrane Journal
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• v.24 no.6
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• pp.472-483
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• 2014

This study is preparation of microporous membranes by using macrocyclic metal ion complexes and extended cage complexes. It is a more favorable way to existing methods because polymer and metal ion-ligand complex system provides a fine control over the phase transition behavior. Chemical functionalization of the polar surface can be obtained. Metal-templated condensation of cyclohexanedione dioxime, hydroxyphenylboronic acid in the presence of metal salts proceeds cleanly in methanol to furnish the metal clathrochelate complexes. Organic/inorganic hybrid membranes were prepared with polyethersulfone (PES), polyvinylpyrrolidone (PVP), ethyleneglycol butyl ether (BE), metal clathrochelate s and DMF by using nonsolvent induced phase inversion method. The structure of membranes was characterized with scanning electron microscopy (SEM) and microflow permporometer. The addition of Fe(II) clathrochelate complex with p-hydroxyphenyl group leads to changes of membrane morphology such as narrow mean pore size distribution, increase of surface pore density and decrease of the largest pore size.