• Journal of the Optical Society of Korea
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• 제16권2호
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• pp.174-180
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• 2012

In this study, the feasibility of spectral domain optical Doppler tomography for measuring blood flow characteristics in a micro-tube was demonstrated through several experiments. The use of an SD-ODT system in blood flow measurement can provide high resolution images (5 microns resolution). We prepared three capillary tubes to reveal the effect of different concentrations of hematocrit ratio (HR). One tube serves as the control. The two other tubes contained different concentrations of HR (5%, 25%). Three different capillary tube inlet flow velocities were tested in the present study. The Reynolds number (Re) which is based on the capillary tube inner diameter ranges from Re=6 to 48. We calculated a Doppler shift of the power spectrum of the temporal interference fringes with Kasai autocorrelation function to achieve the velocity profile of the flow. As a result, SD-ODT systems could not detect the cell depletion layer in the present study due to the limitation of spatial resolution. Nevertheless, these systems were proven to be capable of observing the RBCs of blood.

• 대한기계학회논문집B
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• 제31권4호
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• pp.392-397
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• 2007

We developed a microfluidic platform able to control the trap and release of magnetic beads used for separation of a specific biomolecules. The magnetic beads can be trapped and released conditionally by controlling the difference between the Stokes force induced by the fluid flow and magnetic force resulting from a permanent magnet. The permanent magnet of CoNiP alloy is electroplated. It is characterized to have the 1369 Oe of coercivity, 1762 Gauss of remanence, and 0.603MGOe of (BH)max. Through the experimental and numerical investigation, the magnetic beads are trapped under the flow velocity of 17 ${\mu}m/s$ and are released perfectly above the velocity of 174 ${\mu}m/s$.

• Design & Manufacturing
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• 제13권2호
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• pp.1-5
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• 2019

In this study, micro cellular injection molding of automobile head lamp housing with uneven thickness structure was performed to obtain improvement on deformation and light-weight of the part. The thickness of the presented model was uniformly modified to control the deformation of the molded part. In order to maximize the lightweight ratio, the model having an average thickness of 2.0 mm were thinly molded to an average thickness of 1.6 mm. GFM(Gas Free Molding) and CBM(Core Back Molding) technology were applied to improve the problems of the conventional foam molding method. Equal Heat & Cool system was also applied by 3D cooling core and individual flow control system. Warpage of the molded parts with even cooling was minimized. To improve the mechanical properties of foamed products, complex resin containing nano-filler was used and variation of mechanical properties was evaluated. It was shown that the weight reduction ratio of products with light-weighted injection molding was 8.9 % and the deformation of the products was improved from the maximum of 3.6 mm to 2.0 mm by applying Equal Heat & Cool mold cooling system. Also the mechanical strength reduction of foamed product was less than 12% at maximum.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.2070-2075
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• 2004

Performance of a solid oxide fuel cell (SOFC) can be enhanced by converting thermal energy of its high temperature exhaust gas to mechanical power using a micro gas turbine (MGT). A MGT plays also an important role to pressurize and warm up inlet gas streams of the SOFC. In this study, the influence of performance characteristics of the tubular SOFC on the hybrid power system is discussed. For this purpose, detailed heat and mass transfer with reforming and electrochemical reactions in the SOFC are mathematically modeled, and their results are reflected to the performance analysis. The analysis target is 220kWe SOFC/MGT hybrid system based on the tubular SOFC developed by Siemens-Westinghouse. Special attention is paid to the ohmic losses in the tubular SOFC counting not only current flow in radial direction, but also current flow in circumferential direction through the anode and cathode.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.31-35
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• 2008

본 시험장치는 가스터빈 관련 교육기관, 연구소 등에 가스터빈 엔진의 작동 원리와 구조에 대한 기초지식을 제공하고 가스터빈 엔진의 이론적 열역학 계산을 실제 성능시험을 통하여 비교해 볼 수 있도록 개발되었다. 추력 30lbf급 마이크로 터보제트 엔진을 대상으로 하여 NI DAQ(데이터 수집)장치와 LabVIEW 프로그램으로 각 구성품의 온도, 압력과 추력, 연료유량, 공기유량 등의 실시간 데이터를 모니터링 및 획득할 수 있도록 시험장치를 구성하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.349-352
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• 2001

FACTS technology is developed into the sophisticated system technology which combines conventional power system technology with power electronics, micro-process control, and information technology. Its objectives are achieving enhancement of the power system flexibility and maximum utilization of the power transfer capability through improvements of the system reliability, controllability, and efficiency [1]. As a series and shunt compensator, UPFC consists of two inverters with common dc link capacitor bank. It controls the magnitude of shunt bus voltage and real and reactive power flow of transmission line[2]. In this paper, we present the design, implementation and test results of developed 20kVA level prototype UPFC. It is applied to power system simulator and controls the real and reactive power flow and shunt bus voltage magnitude.

• Asian Pacific Journal of Cancer Prevention
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• 제15권8호
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• pp.3471-3476
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• 2014

Background: Aberrant expression of the microRNA-29 family is associated with tumorigenesis and cancer progression. As transport carriers, tumor-derived exosomes are released into the extracellular space and regulate multiple functions of target cells. Thus, we assessed the possibility that exosomes could transport microRNA-29c as a carrier and correlations between microRNA-29c and apoptosis of bladder cancer cells. Materials and Methods: A total of 28 cancer and adjacent tissues were examined by immunohistochemistry to detect BCL-2 and MCL-1 expression. Disease was Ta-T1 in 12 patients, T2-T4 in 16, grade 1 in 8, 2 in 8 and 3 in 12. The expression of microRNA-29c in cancer tissues was detected by quantitative reverse transcriptase PCR (QRT-PCR). An adenovirus containing microRNA-29c was used to infect the BIU-87 human bladder cancer cell line. MicroRNA-29c in exosomes was measured by QRT-PCR. After BIU-87 cells were induced by exosomes-derived microRNA-29c, QRT-PCR was used to detect the level of microRNA-29c. Apoptosis was examined by flow cytometry and BCL-2 and MCL-1 mRNA expressions were assessed by reverse transcription-polymerase chain reaction. Western blotting was used to determine the protein expression of BCL-2 and MCL-1. Results: The expressions of BCL-2 and MCL-1 protein were remarkably increased in bladder carcinoma (p<0.05), but was found mainly in the basal and suprabasal layers in adjacent tissues. The expression of microRNA-29c in cancer tissues was negatively correlated with the BCL-2 and MCL-1. The expression level of microRNA-29c in exosomes and BIU-87 cells from the experiment group was higher than that in control groups (p<0.05). Exosome-derived microRNA-29c induced apoptosis (p<0.01). Although only BCL-2 was reduced at the mRNA level, both BCL-2 and MCL-1 were reduced at the protein level. Conclusions: Human bladder cancer cells infected by microRNA-29c adenovirus can transport microRNA-29c via exosomes. Moreover, exosome-derived microRNA29c induces apoptosis in bladder cancer cells by down-regulating BCL-2 and MCL-1.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.158-164
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• 2011

When a train passes a conventiaonl tunnel at high speed, external pressure variation problem arises. It is known that this issue can be reduced by control the tunnel length. We studied the variances of external pressure variation within the tunnel, by altering length of the dummy tunnel duct. We also studies the variances of micro-pressure waves at the exit of tunnel, by altering surface area of dummy tunnel duct. For analyzing this train-tunnel relation problem, axisymmetric steady compressible flow solver was used.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1993년도 추계학술대회논문집
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• pp.21-30
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• 1993

This paper describes the development of a simulation model of nuclear power plant operators including cognitive aspects by using a network modeling soft ware, Micro-SAINT (System Analysis of Integrated Networks of Tasks) for the analysis of operator performance. Network model description based on Micro-SAINT includes tasks, resources, precedence relations among tasks, flow of information and PSFs (Performance Shaping Factors) on task performance. We have tried to evaluate the performance with several performance measures such as the number of tasks allocated, relative time presure among operators within a shift, for the selected test accident scenarior; small-break LOCA (Loss of Coolant Accident) in a PWR (Pressurized Water Reactor) type nuclear power plant.

• 설비공학논문집
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• 제13권2호
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• pp.80-87
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• 2001

Microencapsulated PCM particles are mixed with distilled water and utilized to evaluate its characteristics and performance as a thermal storage medium transporting heat. For the present study, tetradecane(C$_14H_30, T_m=5.5^{\circ}C$) is capsulated in the core with the melamine of its surface. The size of particles is well-controlled under 10${\mu}{\textrm}{m}$ in the way of in-situ polymerization with melamine-formaldehyde resin. For the experiment, the concentrations of slurries are prepared for 20wt%, 30wt%, and 40wt%. The results are compared with those of water and 100% tetradecane oil. The pure water and tetradecane start solidifying within 20 minutes after introducing cooling water into the thermal storage tank whose tank whose flow rates are varied by 125cc/min, 250cc/min, and 500cc/min. However, MicroPCM slurries are required relatively longer period of time for their phase change than pure phase change materials. That is, the entrained MicroPCM particles control its heat transfer in terms of natural convection and conducting to them.