• Toxicological Research
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• 제26권3호
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• pp.203-208
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• 2010

Bronchoalveolar lavage (BAL) is a useful tool in researches and in clinical medicine of lung diseases because the BAL fluid contains biochemical and cytological indicators of the cellular response to infection, drugs, or toxicants. However, the variability among laboratories regarding the technique and the processing of the BAL material limits clinical research. The aim of this study was to determine the suction frequency and lavage fraction number necessary to reduce the variability in lavage using male Sprague-Dawley rats. We compared the total cell number and protein level of each lavage fraction and concluded that more cells and protein can be obtained by repetitive lavage with a suction frequency of 2 or 3 than by lavage with a single suction. On the basis of total cell recovery, approximately 70% of cells were obtained from fractions 1~3. The first lavage fraction should be used for evaluation of protein concentration because fractions 2~5 of lavage fluid were diluted in manifolds. These observations were confirmed in bleomycin-induced inflamed lungs of rats. We further compared the BAL data from the whole lobes with data from the right lobes and concluded that BAL data of the right lobes represented data of the whole lobes. However, this conclusion can only be applied to general lung diseases. At the end, this study provides an insight into the technical or analytical problems of lavage study in vivo.

• Journal of Biosystems Engineering
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• 제33권3호
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• pp.179-185
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• 2008

The seeding rates of the vacuum suction nozzle seeders are affected by the jumping height of the seeds on the vibrating seed hopper. This study was performed to investigate the optimum vibration condition of the seed hopper on the vacuum suction nozzle seeder for improving seeding performance. Experiments were carried out to determine the vibration conditions of the seed hopper by air pressure and eccentric weight, and to optimize the seed-pickup performance of each nozzle by suction pressure. As the result with the experiments, the fluctuations of the jumping height of the seeds were showed at amplitude 0.4 mm and frequency 42 Hz, and jumping heights of the seeds were increased as the air pressure increase and the eccentric weight decrease, regardless number of seeds of the hopper. The best seeding rate of the seed hopper was 98% at the 300-seed cell, when the condition of the seed hopper was the suction air pressure of 94.6 kPa-abs., amplitude and frequency of the seed hopper vibration were at 0.57 mm and 43.6 Hz, respectively. The optimum vibrating conditions of the seed hopper were decided into frequency 43.6-43.8 Hz and the amplitudes 0.61-0.62 mm.

• The Korean Journal of Physiology
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• 제20권1호
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• pp.43-52
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• 1986

The influences of extracellular $Ca^{2+}\;and\;K^+$ upon the spike action potentials were studied in isolated uterine strips of rat. Regular, rhythmic uterine contractions were induced by the administration of oxytocin$(0.2{\sim}0.5\;I.U.)$, and recorded with force transducer. Spike action potentials were extracellularly measured by use of suction electrode, and compared with those recorded intracellularly by glass microelectrode. The results obtained were as follows : 1) The frequency and duration of spike bursts, and the number of spikes in a burst could be analyzed by use of both methods. But the absolute values of membrane potential were not measurable with the suction electrode. 2) The duration of contraction$(CD_{90};\;the\;duration\;of\;90%\;relaxation)$ was lengthened from the control 17.0 sec to 20.6 sec, in parallel with the increase of spike number from the control 21 to 26, as the increase in $Ca^{2+}$ concentration from 2 to 4 mM. 3) The amplitude and frequency of contractions were gradually decreased, simultaneously with the decrease in the number of spikes in a burst, when the $Ca^{2+}-antagonist$, verapamil was administered cumulatively. 4) The number of spikes was changed from the control 15 to 7, in cabs of the administration of ver)'low dose of verapamil$(10^{-6}\;g/l)$. 5) Increase in the numbers of spike bursts was well matched to the increase in frequency of contractions when extracellular $K^+$ was increased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.472-478
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• 2000

An experimental study is performed to analyze flow structures behind a local suction/blowing in a flat-plate turbulent boundary layer, The local forcing is given to the boundary layer flow by means of a sinusoidally oscillating jet issuing from a thin spanwise slot at the wall. The Reynolds number based on the momentum thickness is about $Re_{\theta}=1700$. The effects of local forcing are scrutinized by altering the forcing frequency $(0.011{\leq}f^+{\leq}0.044)$. The forcing amplitude is fixed at $A_0=0.4$. It is found that a small local forcing reduces the skin friction, and this reduction increases with the forcing frequency. A phase-averaging technique is employed to capture the coherent structures. Velocity signals are decomposed into a periodic part and a fluctuating part. An organized spanwise vortical structure is generated by the local forcing. The larger reduction of skin friction for the higher forcing frequencies is attributed to the diminished adverse effect of the secondary vortex. An investigation of the random fluctuation components reveals that turbulent energy is concentrated near the center of vortical structures.

• 한국생산제조학회지
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• 제20권4호
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• pp.464-471
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• 2011

We tried to analyze sound field of the interior of housing installed with an impeller using the Boundary Element Method (BEM) with the Kirchhoff-Helmholtz integral equation. In order to increase the accuracy of our analysis, reverse engineering technology, which has been developed in recent years. We measured and treated geometrical data with 3D scanning of the practical research object. After modeling by the reverse engineering, we analyzed variation of the BPF as adding vibration frequency and variation of the sound field of the interior of housing by changing the number of impeller blades. We also tried an analysis of free degree variation. Then, we proposed the analysis accuracy and noise reducing method by analysis result.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.159-165
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• 2008

A sirocco fan is widely used for discharging pollutants of a kitchen space since it is able to generate a relatively high air flow rate considering its small size and makes less noise than a axial fan or a centrifugal fan. However, it has a problem because its efficiency is low, and power consumption is larger. Performance of a sirocco fan is influenced by various factors such as number of the fan blades, diameter of the fan, geometry of the fan, geometry of its housing, revolution frequency, static pressure condition, and etc. This research investigated the effect on the performance of geometry of the housing. For CFD analysis, we used a commercial code, SC/Tetra, and used a sliding mesh method to give the same condition as an actual state. Verification of the CFD results is done by comparison of experimental data and numerical one about the suction flow rate, and it is confirmed that two results are well consistent. After we changed the shape of housing according to Archimedes' screw, we observed that suction efficiency is improved by 10.7% maximum.

• The Korean Journal of Physiology
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• 제19권1호
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• pp.1-13
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• 1985

The influences of $Ca^{2+}-antagonists$, verapamil and $Mn^{2+}$, upon the spontaneous electrical activity and contractions were studied in guinea-pig taenia coli. Spontaneous contractions were recorded with force transducer, and spike action potentials were measured extracellularly by use of suction electrode. All experiments were performed in tris-buffered Tyrode solution Which was aerated With 100% $O_2$ and kept at $35^{\circ}C$. The results obtained were as follows : 1) Verapamil suppressed the frequency and amplitude of spontaneous contractions dose dependently, and blocked completely mechanical responses at the concentration of 1 mg/1. 2) The frequency of bursts of spike discharge(bursts frequency) and the number of spikes in a burst(spikes frequency) were reduced in a dose·dependent manner within the concentration range of $10^{-5}$ to $10^{-3}g/l$, and bursts frequency was affected more readily at a low concentration of $10^{-5}g/l$ verapamil. 3) The verapamil_induced suppression of spontaneous contractions in the Tyrode solution containing 1 mM $Ca^{2+}$ was completely antagonized by the addition of extra $Ca^{2+}$ to the Tyrode solution $(2\;m\;MCa^{2+})$. 4) $Mn^{2+}$ suppressed the amplitude of spontaneous contractions, whereas $Mn^{2+}$ accelerated the frequency dose-dependently within the range of low concentrations$(10^{-7}\;to\;10^{-4}\;M\;Mn^{2+})$. 5) The bursts frequency determining frequency of spontaneous contractions was increased in a dose-dependent manner, whereas the spikes frequency known to determine the contractions amplitude was reduced within the range of low concentrations. At a high concentration of 1 mM $Mn^{2+}$, however, all spontaneous contractile responses were blocked simultaneously with the disapperance of electrical activity. 6) The frequency and amplitude of spontaneous contractions altered by $Mn^{2+}$ in 1mM $Ca^{2+}$ Tyrode were increased by extra $Ca^{2+}(2mM)$.

• 한국의료질향상학회지
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• 제8권1호
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• pp.44-55
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• 2001

Background : This study aimed at identifying the effect of the standardized protocol on lowering the incidence of the ventilator associated pneumonia(VAP). Methods : The standard protocol focusing on decreasing VAP was made and applied at 5 ICUs (Medical ICU, surgical ICU, Respiratory ICU, Neonatal ICU, Pediatric ICU) in a university affiliated tertiary hospital, from April 1, 2000 to Oct 31, 2000. The protocol involved 3 parts : hand washing, the suctioning method and ventilator circuit management. All the nursing personnel received intensive education which was consisted of lecture, video film and demonstration. 176 nurses reported the performance of handwashing pre and post intervention. And randomly selected 15 nurses were observed by charge nurse and the handwashing practice was analyzed pre and post intervention. The incidence of VAP was compared with the former year incidence. Results : The self reported frequency of hand washing increased. In the direct observation of handwashing, the frequency, time, thoroughness of hand washing during 8 hours day duty was found to be improved. The frequency was increased from 1.1 time to 4.1 times; the time was improved from 1.7 seconds to 5.7 seconds and the thoroughness of the washing practice was from 0.2 times to 3.0 times respectively (p<0.001). The incidence of VAP decreased from at a rate of 15.63 number of case per 1,000 ventilator-day (April 1~August 31, 1999) to 7.23 number of case per 1,000 ventilator-days(April 1~Oct 31, 2000)(P<0.001). Conclusion : We developed the protocols which included hand washing, the suctioning method, and ventilator circuit management. Through the implementation of the protocol, the performance of hand washing improved and the VAP incidence rate in ICU was decreased.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.421-426
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• 2005

Optimal design of serial connected PZT driven micro compressor was investigated. Modeling equations were derived using energy equation and mass conservation equation. The results show that mass flow rate was increased as number of connected micro compresses is increased. As pressure difference between suction port and discharge port in compressor group is increased, connected compressors have much more mass flow rate than single compressor. Mass flow rate is also increased as driving frequency is increased. And optimal design scale is suggested for highest efficiency or highest mass flow rate.

• 해양환경안전학회지
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• 제24권1호
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• pp.92-100
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• 2018

난류경계층이 유지되기 위한 에너지 공급은 경계층 내 구조물인 와류들의 상호작용으로 끊임없이 이루어진다. 이러한 난류 유동은 수송분야의 마찰저항 및 해양구조물의 침식 및 진동을 유발하기 때문에 유동 제어를 위한 연구가 활발히 진행되고 있다. 이러한 제어의 극대화를 위해서는 난류 에너지 전달이 어떻게 이루어지는지에 대한 메카니즘 규명이 필수적이고, 이를 위해서는 층류경계층 내 유동현상으로 파악하는 것이 명확하고 용이하다는 장점이 있다. 따라서, 본 연구에서는 층류경계층 내 평판에 반구를 설치하여 역압력구배을 발생시킴으로써 교란된 유동현상의 상호작용을 분석하였다. 즉, 반구를 둘러싼 목걸이 와류와 반구 표면의 유동 박리에 의한 후류영역에서 머리핀 와류가 생성되어 상호 유기적으로 영향을 주고받는다. 이 과정에서 목걸이 와류는 후류영역으로 높은 운동량의 유체를 유입시켜 머리핀 와류의 발생 주파수를 증가시킨다. 반구 전방에 구멍을 뚫어 국부적인 흡입제어로 목걸이 와류의 와도를 감소시킴으로써 그 영향이 완화되는 과정을 유동 가시화 및 열선유속계로 측정하여 정성 및 정량적으로 분석하였다.