• 대한기계학회논문집B
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• 제30권9호
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• pp.834-841
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• 2006

In the present wort the Laser-induced Fluorescence (LIF) technique and Confocal Laser Scanning Microscopy (CLSM) have been combined to measure the temperature distribution across a micro-scale liquid layer as a direct and non-invasive method. Only the fluorescent light emitted from a very thin volume around a focal plane can be selectively detected, and it enables us to measure the liquid temperatures even at the close vicinity of the walls. As an experimental verification, a test section consists of two flat plates (for heating and cooling, respectively) separated by about 240 microns was made, and the methanol mixed with a temperature-sensitive dye, Rhodamine B, was filled in the gap between them. The measured temperature distribution across the gap showed good linearity, which is a typical characteristic of conduction heat transfer through a thin liquid layer. In result, the CLSM-LIF technique proposed in the present study was found to be a promising method to measure the local temperatures in the liquid flow field in microfluidic devices.

• 한국발생생물학회지:발생과생식
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• 제16권2호
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• pp.95-100
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• 2012

Bisphenol A(BPA)는 약한 estrogen 활성도를 보이는 화학물질로서 착상 전 배아나 태아에 영향을 미쳐, 출생 후 그들의 신체발달에 변화를 초래한다고 알려져 있다. 본 연구는 인체에서 임신 중기에 양수 내 BPA 농도를 측정하였으며, 측정된 농도에 따라 임신결과에 영향을 미치는지 여부를 알아보고자 하였다. 임신 15주에서 20주 사이에 유전학적 적응증으로 양수천자 검사를 시행 받았던 120명의 임신부 양수를 연구대상으로 ELISA 방법으로 농도를 측정하였다. 양수천자의 가장 많은 적응증은 35세 이상의 고령 임신부였다. BPA는 모든 양수에서 검출이 가능하였으며, 그 농도는 최저치 0.89 ng/mL부터 최고치 37.13 ng/mL까지의 분포를 보였고, 평균치는 7.24 ng/mL이었다. 양수 내 BPA 농도가 여러 임신결과들과 관련성이 있는지를 알아보기 위해 임신부 나이 35세 이상 대 미만, 남자 태아 대 여자 태아, 분만 당시 재태 연령 37주 이상 대 미만, 출생 당시 신생아 체중 2.5 kg 이상 대 미만으로 각각 나누어, 두 군간에 농도를 비교한 결과, 통계학적으로 유의한 차이는 없었다. 본 연구는 한국인 임신부를 대상으로 최초로 양수 내 BPA 농도에 관한 보고이다. 본 연구결과 BPA 농도는 임신부 나이나 태아성별에 따라 차이를 보이지 않았으며, 조산이나 저체중아의 발생과도 관련이 없음을 알 수 있었다. 향후 산전 BPA 노출이 배발생에 영향을 미치는지에 대한 연구가 필요하다고 사료된다.

• 기본간호학회지
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• 제18권2호
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• pp.168-176
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• 2011

Purpose: The purpose of this study was to identify differences between intake and output balance and body weight changes and to identify factors related to differences in critically ill patients. Methods: The participants for this descriptive correlational study were 65 medical surgical ICU patients. The data were collected from patient medical records. Results: Mean age of the patients was 63.80 years (${\pm}15.21$). Body weight changes for 48 hours averaged 281.54g (${\pm}2210.48$). I&O balance for 48 hours corrected for insensible loss averaged 398.1ml. Differences ranged from 45mL to 7,535mL. In the distribution of absolute difference between body weight change and intake and output balance, only 40% of the patients were within less than 1,000 mL. Factors relating to accurate measure of intake and output were ventilation methods, respiration patterns, and edema status. Conclusion: Although mean values of weight change and I&O balance for all patients were very close, the range of differences was very wide indicating that, for many patients, intake and output is not an appropriate indicator of body fluid balance. Therefore, because of the frequency fever and/or hyperventilation, nurses need to use caution when using intake and output balance only to estimate current body fluid status for critically ill patients.

• 센서학회지
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• 제23권6호
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• pp.368-376
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• 2014

In order to measure the segmental impedance of the body, a bioelectrical impedance measurement system (BIMS) using multi-frequency applying method and two-electrode method was implemented in this study. The BIMS was composed of constant current source, automatic gain control, and multi-frequency generation units. Three experiments were performed using the BIMS and a commercial impedance analyzer (CIA). First, in order to evaluate the performance of the BIMS, four RC circuits connected with a resistor and capacitor in serial and/or parallel were composed. Bioelectrical impedance (BI) was measured by applying multi-frequencies -5, 10, 50, 100, 150, 200, 300, 400, and 500 KHz - to each circuit. BI values measured by the BIMS were in good agreement with those obtained by the CIA for four RC circuits. Second, after measuring BI at each frequency by applying multi-frequency to the left and right forearm and the popliteal region of the body, BI values measured by the BIMS were compared to those acquired by the CIA. Third, when the distance between electrodes was changed to 1, 3, 5, 7, 9, 11, 13, and 15 cm, BI by the BIMS was also compared to BI from the CIA. In addition, BI of extracellular fluid (ECF) was measured at each frequency ranging from 10 to 500 KHz. BI of intracellular fluid (ICF) was calculated by subtracting BI of ECF measured at 500 kHZ from BI measured at seven frequencies ranging from 50 to 500 KHz. BI of ICF and ECF decreased as the frequency increased. BI of ICF sharply decreased at frequencies above 300 KHz.

• 한국미생물·생명공학회지
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• 제45권4호
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• pp.343-353
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• 2017

In the present study, the isolation of selenium (Se)-enriched bacteria from rumen fluid and hot spring water was carried out. Rumen fluid samples were taken from cannulated goats fed a basal diet and the water samples were collected from Selayang hot spring, Selangor-Malaysia. A total number of 140 Se-tolerant isolates were obtained aerobically using an Se-enriched medium and spread plate technique. All the isolates were initially screened for the ability to transform the Se-containing medium to a red-orange culture using a spectrophotometer. Twenty isolates of dark red-orange medium were selected for a screening of the highest Se-containing protein accumulating strains using the dialysis technique and icp.ms to measure the Se content. Four isolates, identified as Enterobacter cloacae (ADS1, ADS7, and ADS11), and Klebsiella pneumoniae (ADS2) from rumen fluid origin, as well as, one isolate from hot spring water (Stenotrophomonas maltophilia (ADS18)), were associated with the highest biomass organic Se-containing protein when grown in a medium enriched with $10{\mu}g/ml$ sodium selenite. In addition, around $50{\mu}g/100{\mu}g$ of the absorbed inorganic Se was accumulated as an organic form. Organic Se-containing protein in all the selected strains showed antioxidant properties in the range of 0.306 to 0.353 Trolox equivalent antioxidant capacity (TEAC) mg/ml. Therefore, these strains may offer a potential source of organic Se due to their Se-tolerant nature and higher biomass organic to inorganic Se ratio.

• 대한기계학회논문집
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• 제8권2호
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• pp.154-161
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• 1984

본 연구에서는 고정밀 아날로그-디지탈 변환기와 마이크로 프로세서(micropr- ocessor) Intel 8085를 사용하여 비정상 아날로그(analog)신호를 왜곡이 없이 디지탈 량으로 직접 변환하여 자료처리하였다. 또한 비정상 열선법은 열선에 전류를 가하여 열선이 열원이며 동시에 온도계의 두 가지 역할을 하므로, 전기전도성이 있는 액체는 적합하지 못한 단점이 있다. 이를 해결하기 위하여 열선에 얇은 절록피복층을 입혀 전기전도성 액체의 열전도율을 측정할 수 있는 가능성에 대한 연구를 시도하였다.

• 한국물환경학회지
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• 제30권2호
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• pp.166-174
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• 2014

Velocity gradient, G, a measure of the average velocity gradient in the fluid has been applied for complete mixing of chemicals in mechanical mixing devices. G values were calculated by the power input transferred to fluid in turbulent and transient range. Chemical reactions occur so fast that total mass transfer time required for even distribution of the chemicals determine the overall reaction time. The total mass transfer time is composed of the time for complete mixing through the reactor and for diffusion of the chemicals into the eddy. Complete mixing time was calculated by CFD (computer fluid dynamics) and evaluated by tracer tests in 2 liter jars at different rotating speeds. Turbulent range, Reynolds number above 10,000 in regular 2 liter jars occurred at revolution speed above 100 rpm (revolution per minute), while laminar range occurred at revolution speed below 10 rpm. A typical range of rotating speed used in jar tests for water and wastewater treatment was between 10 and 300 rpm, which covered both transient and turbulent range. G values supplied from a commercial jar test apparatus showed big difference from those calculated with power number specially in turbulent range. Diffusion time through eddy decreased 1.5 power-law of rotating speed. Complete mixing time determined by pumping number decreased increases in rotating speed. Total mass transfer time, finally, decreases as rotating speed increases, and it becomes 1 sec at rotating speed of 1,000 rpm. Complete mixing times evaluated from tracer tests showed higher than those calculated by power number at higher rotating speed. Complete mixing times, however, calculated by CFD showed similar to those of experimentally evaluated ones.

• 한국공작기계학회논문집
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• 제11권6호
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• pp.75-82
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• 2002

Design for a quiet operation of fluid power system requires the understanding of noise and vibration characteristics of the system. It's not easy to analyze noise problem in hydraulic cylinder used in typical actuator Because they've got complex fluid dynamics. One of the fundamental problems associated with the hydraulic system is the pulsating flow in pipe lines, which can be tackled by the analysis under simplifying assumptions. The present study focuses on theoretic analysis and experimental study on the dynamics of laminar pulsating flow in a circular pipe. We analyze the propagation characteristics of the pressure pulse within a hydraulic pipe line taking into account the pulsating flow frequency variation. We also measure instantaneous pressure pulses within pipe line to identify the transfer functions. We conduct series of experiments to investigate the propagation characteristics of pressure pulse for various pressure of pulsating flow. The working fluid of the present study is ISO VG46 and the temperature ranges from 20 to $60^{\circ}$ with normal pressure at 4000kPa. The flow rate is measured by using an ultrasonic flow meter. Pressures at fixed upstream and downstream positions are measured concurrently. The electric signals of the pressure sensor are stored and analyzed using a system analyzer(PKE 983 series). The frequency is varied in the range of 10~500Hz. The Reynolds number is kept below 2,000. In the present study, boundary condition was varied by installing a surge tank and an orifice at the end of pipe. Experimental and theoretical results were compared each other under various boundary conditions.

• 한국산업정보학회논문지
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• 제28권6호
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• pp.99-105
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• 2023

고도의 생존성이 요구되는 잠수함은 군의 전략자산에서 가장 중요한 전투 무기체계 중 하나이다. 일반적인 재래식 잠수함은 추진시스템을 작동하기 위해 공기가 필요해 필연적으로 스노클 항해를 하며 잠수함 내부로 공기를 공급해야 한다. 그리고 스노클 항해 시 수중으로 배출된 폐기 가스는 주변 유체를 가열해 온도 항적을 형성하고 결과적으로 잠수함의 생존성을 감소시킨다. 본 연구에서는 수중 잠수함의 폐기로 인해 형성된 수면의 온도 항적에 관한 기초 실험 연구를 수행하였다. 이를 위해 국내 도입된 잠수함의 추진시스템과 항해 조건 자료를 수집하였으며, 온도 항적을 계측하기 위한 실험 시스템을 구현하였다. 실험 결과 수조로 주입된 고온 기포는 작은 크기로 부서져 주위를 둘러싼 유체와 유사한 수준으로 온도가 감소하였으며, 이를 열전대 센서로 확인하였다. 그리고 수면의 온도 항적을 계측하기 위한 열화상 시스템의 결과에서도 온도 항적은 계측되지 않았다.

• Journal of Magnetics
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• 제19권2호
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• pp.185-191
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• 2014

In this study we evaluated that flow rate changes affect the (time of flight) TOF image and contrast-enhanced (CE) in a three-dimensional TOF angiography. We used a 3.0T MR System, a nonpulsatile flow rate model. Saline was used as a fluid injected at a flow rate of 11.4 cm/sec by auto injector. The fluid signal strength, phantom body signal strength and background signal strength were measured at 1, 5, 10, 15, 20 and 25-th cross-section in the experienced images and then they were used to determine signal-to-noise ratio and contrast-to-noise ratio. The inlet, middle and outlet length were measured using coronal images obtained through the maximum intensity projection method. As a result, the length of inner cavity was 2.66 mm with no difference among the inlet, middle and outlet length. We also could know that the magnification rate is 49-55.6% in inlet part, 49-59% in middle part and 49-59% in outlet part, and so the image is generally larger than in the actual measurement. Signal-to-noise ratio and contrast-to-noise ratio were negatively correlated with the fluid velocity and so we could see that signal-to-noise ratio and contrast-to-noise ratio are reduced by faster fluid velocity. Signal-to-noise ratio was 42.2-52.5 in 5-25th section and contrast-to-noise ratio was from 34.0-46.1 also not different, but there was a difference in the 1st section. The smallest 3D TOF MRA measure was $2.51{\pm}0.12mm$ with a flow velocity of 40 cm/s. Consequently, 3D TOF MRA tests show that the faster fluid velocity decreases the signal-to-noise ratio and contrast-to-noise ratio, and basically it can be determined that 3D TOF MRA and 3D CE MRA are displayed larger than in the actual measurement.