• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.50.1-50.1
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• 2005

• 한국정보과학회논문지:정보통신
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• 제32권6호
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• pp.732-744
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• 2005

차등서비스 네트워크(Diffserv Network)의 AE 서비스(Assured Forwarding Service)에 대한 기존 연구는 전송률 분배에서 RTT(Round Trip Time), 목표 전송률(Target Rate), UDP의 영향 등에 대한 고려가 부족하며, UPN(Under-Provisioned Network) 상황에서는 최선형 서비스처럼 동작하는 문제가 있다. 본 논문에서는 이러한 문제를 해결하기 위하여 tmTRA3CM(tcp-microflow based Target rate and RTT Aware Three Color Marker), um3CM(udp-microflow based Three Color Marker), TRBD(Target Rate Based Dropping) 기법 및 목표 전송률 조정함수 등으로 구성되는 PFDSA (Proportionally Fair Differentiated Service Architecture)를 제안하였다. ns 시뮬레이터를 이용한 PFDSA와 기존 방식들의 비교 분석 결과, 제안한 PFDSA는 RTT 및 UDP 영향 제거, 목표 전송률에 비례하는 대역분배 및 UPN 상황에서의 공평한 대역분배 기능이 기존 방식에 비해 우수함을 확인할 수 있었다.

• Rapid Communication in Photoscience
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• 제2권3호
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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.

• 대한기계학회논문집B
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• 제28권2호
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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.

• 대한기계학회논문집A
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• 제28권12호
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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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• 제20권5호
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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.

• 대한기계학회논문집B
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• 제34권4호
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• pp.349-354
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• 2010

연료전지는 환경문제와 천연자원 고갈을 해결할 수 있기 때문에 가장 주목받고 있는 새로운 동력원이다. 본 논문에서는 마이크로 연료전지의 효율을 높이기 위해 다양한 형상에 대해 마이크로 채널에서 수소가스 유동을 수치해석 하였다. 이미 개발된 채널과 새롭게 고안된 채널, 모두 여섯 개의 다른 형상을 가진 채널이 같은 유동 특성과 경계조건으로 수치해석을 수행하였다. 수치해석 결과를 통해 유속, 유동분포, 유동균일성 등이 채널형상에 따라 영향을 많이 받는 것을 알았다. 이에 수소 가스 유동을 고려한 채널형상 최적화를 통해 연료전지의 성능을 향상시키고자 하였다. 수치해석을 통한 최적화된 채널형상을 사용한 PEMFC 실험결과 평균보다 높은 전류밀도를 나타내었다. 그러나 내구성이 낮았다.

• 한국농공학회논문집
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• 제54권1호
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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.

• 멤브레인
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• 제24권1호
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• pp.50-62
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• 2014

상 전이 공정을 이용하여 polysulfone계 비대칭 정밀 여과막을 제조하였다. Polysulfone/N-methyl-2-pyrrolidone/polyvinylpyrrolidone/phosphoric acid계로 이루어진 casting 용액을 사용하였으며 응고조로는 물을 사용하였다. 멤브레인 제조공정에 적용된 상 전이 공정으로 증기 유도 상 전이 공정을 적용하였으며 상대습도 74%에서 캐스팅 판의 온도와 노출 시간을 조절한 결과 기공의 크기와 구조에 있어 변화를 관찰할 수 있었다. 제조된 멤브레인의 구조는 SEM과 microflow permporometer를 사용하여 조사하였다. Phosphoric acid의 첨가는 조밀한 스펀지 형태의 멤브레인을 느슨한 스펀지 형태의 멤브레인으로 변화시켰으며 촉매량의 Phosphoric acid 첨가로도 평균 기공크기는 거의 $0.2{\mu}m$ 정도 커지고 유량도 약 3,000 LMH가 증가하였다. 캐스팅 판의 온도와 노출 시간의 변화는 표면층의 구조, 기공의 크기 및 공극률에 큰 변화를 가져옴을 확인할 수 있었다.

• 멤브레인
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• 제24권6호
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• pp.472-483
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• 2014

본 연구는 거대고리 금속 이온 착화합물과 유도체를 이용하여 미세 다공성 구조를 가지는 분리막의 제조에 관한 것이다. 고분자와 금속이온 리간드 착물 시스템을 이용함으로써 기존의 방법들에 비해 상 전이 과정을 보다 정교하게 제어할 수 있었다. 금속염, cyclohexanedione dioxime, hydroxyphenylboronic acid와의 축합 반응을 통하여 금속 clathrochelate 착물을 얻을 수 있었다. PES, PVP, BE와 금속 clathrochelate 착물을 DMF에 녹인 후 비용매 유도 상 전이법을 통하여 유무기 혼성고분자막을 제조하였다. 제조된 분리막의 구조는 FE-SEM과 microflow permporometer로 조사하였다. p-Hydroxyphenyl group을 가지는 Fe(II) clathrochelate 착물의 첨가는 분리막의 구조에 있어 기공 크기 분산도를 좁혀주고, 표면의 기공 밀도를 높여 주었으며 최대 기공 크기를 감소시킴을 볼 수 있었다.