• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.331-337
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• 1994

In order to develop a $^{18}F$-labelled myocardial perfusion agent(flow tracer) for PET, $^{18}F$-labelled organic ammonium cations were synthesized and evaluated in relation to their biodistribution. Five quaternary organic ammonium compounds were labelled with $^{18}F$ in a side chain with moderate to good yields by direct introduction of $^{18}F$-fluoride. Radiochemical yields have been achieved in 30-40min by the precursors (tosylates) in dimethylsulfoxide 15-60% (decay corrected). The reaction was found to be autocatalyzed. A remote controlled procedure was developed in these synthesis. $^{18}F$-Labelling and HPLC-purification of com-pounds needed about 60 min(Yield; 7-20%). Up to now the two compounds N-4-[$^{18}F$]fluorobutyl-pyridinium cation(1) and N, N dibenzyl-4(2-[$^{18}F$]fluoroethyl)piperidinium cation(2) were investigated in relation to their biodistribution in mice. Compound 1 showed at 1 min post injection the high uptake of 19.22% ID/g organ in the myocardium but a following fast decline to 1.12% ID/g organ after 40min. Uptake of compound 2 was after 1min in the heart 5.90% ID/g organ but after 40min at the relative high value of 4.33% ID/g organ. Heart:blood ratio for compound(1) at 1 min was 8.3, at 40 min 2.6 for compound II 2.0(1min) and 15.0(40 min). As data of compound 2 showed greater heart uptake, slower myocardial release, and higher heart: blood ratios, compound 2 is a good candidate for further evaluation.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.542-547
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• 2001

A non-intrusive Planar Laser-Induced Fluorescence(PLIF) technique was applied to study the turbulent mixing process in a Rushton turbine reactor. Instantaneous and ensemble averaged concentration fields are obtained by measuring the fluorescence intensity of Rhodamine B tracer excited by a thin Nd:Yag laser sheet illuminating the whole center plane of the stirred tank. The gray level images captured by a 14-bit cooled CCD camera can be transformed to the local concentration values using a calibration matrix. The dye injection point was selected at the tank wall with three quarter height (3/4H) from the tank bottom to observe the mixing characteristics in upper bulk flow region. There exist distinct two time scales: the rapid decay of mean concentration in each region after the dye infusion reflects the large scale mixing while the followed slow decay reveals the small scale mixing. The temporal change of concentration probability functions conjectures the two sequential processes in the batch type mixing. An inactive column of water existed above the impeller disk, in which the fluid rotates with the shaft but is isolated from the mean bulk flow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1145-1152
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• 2002

A non-intrusive Planar Laser-Induced Fluorescence(PLIF) technique was applied to study the turbulent mixing process in a Rushton turbine reactor. Instantaneous and ensemble averaged concentration fields was obtained by measuring the fluorescence intensity of Rhodamine B tracer excited by a thin Nd:Yag laser sheet illuminating the whole center plane of the stirred tank. The gray level images captured by a 14-bit cooled CCD camera could be transformed to the local concentration values using a calibration matrix. The dye injection point was selected at the tank wall with three quarter. height (3/4H) from the tank bottom to observe the mixing characteristics in upper bulk flow region. There exist distinct two time scales: the rapid decay of mean concentration after the dye infusion reflects the large scale turbulent mixing while the fellowed slow decay reveals the small scale molecular mixing. The temporal change of concentration variance field conjectures the two sequential processes for the batch type mixing. An inactive column of water is existed above the impeller disk, in which the fluid rotates with the shaft but is isolated from the mean bulk flow.

• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.183-192
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• 2002

Indoor air quality is affected by source strength of pollutants, ventilation rate, decay rate, outdoor level and so on. Although technologies exist to measure these factors directly, direct measurements of all factors are impractical in most field studies. The purpose of this study was to develop an alternative methods to estimate these factors by multiple measurements. Daily indoor and outdoor NO$_2$concentrations for 21 days in 20 houses in summer and winter, Seoul. Using a mass balance model and linear regression analysis, penetration factor (ventilation divided by sum of air exchange rate and deposition constant) and source strength factor(emission rate divided by sum of air exchange rate and deposition constant) were calculated. Subsequently, the ventilation and source strength were estimated. During sampling period, geometric mean of natural ventilation was estimated to be 1.10$\pm$1.53 ACH, assuming a residential NO$_2$decay rate of 0.8 hr$^{-1}$ in summer. In winter, natural ventilation was 0.75$\pm$1.31 ACH. And mean source strengths in summer and winter were 14.8ppb/hr and 22.4ppb/hr, respectively. Although the method showed similar finding previous studies, the study did not measure ACH or the source strength of the house directly. As validation of natural ventilations, infiltrations were measured with $CO_2$tracer gas in 18 houses. Relationship between ventilation and infiltration was statistically correlated (Pearson r=0.63, p=0.02).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.4
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• pp.504-510
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• 2003

Simultaneous measurements of turbulent velocity and concentration field in a stirred mixer tank are carried out by using PIV/LIF technique. Instantaneous velocity fields are measured with a 1K$\times$1K CCD camera adopting the frame straddle method while the concentration fields are obtained by measuring the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. It is found that the general features of the mixing pattern are quite dependent on the local flow characteristics during the rapid decay of mean concentration. However, the small scale mixing seems to be independent on the local turbulent velocity fluctuation.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.520-525
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• 2000

This research is to analyze the ventilation performance of mechanical ventilation systems for indoor air quality control and management. A ventilation performance with supply sites is evaluated in a test model chamber and office room. A $CO_2$ gas as a tracer gas is used to measure the ventilation performance. The ventilation performance is found to increase with increased the ventilation rate. The ventilation performance is analysed with 55% at the supply air of 570 lpm and with 20% at the supply air of 100 lpm in a test chamber. The ventilation performance is better than 15% comparing with natural decay at the supply of 570 lpm in office room.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.101-104
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• 2002

Simultaneous measurement of turbulent velocity and concentration field in a stirred mixer tank is carried out by using PIV/LIF technique. Instantaneous velocity fields are measured by a $1K\times1K$ CCD camera adopting the frame straddle method while the concentration fields are obtained by measuring the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. It is found that the general features of the mixing pattern are quite dependent on the local flow characteristics during the rapid decay of mean concentration. However, the small scale mixing seems to be independent on the local turbulent velocity fluctuation.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.5
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• pp.51-60
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• 2015

In Korea, 69.4 % of duck farms had utilized conventional plastic greenhouses. In this facilities, there are difficulties in controlling indoor environments for raising duck. High rearing density in duct farms also made the environmental control difficult resulting in getting more stressed making their immune system weaker. Therefore, a facility is needed to having structurally enough solidity and high efficiency on the environmental control. So, new design plans of duck house have recently been conducted by National Institute of Animal Science in Korea. As a study in advance to establish standard, computational fluid dynamics (CFD) was used to estimate the aerodynamic problems according to the designs by means of overall and regional ventilation efficiencies quantitatively and qualitatively. Tracer gas decay (TGD) method was used to calculate ventilation rate according to the structural characteristics of duck houses including installation of indoor circulation fan. The results showed that natural ventilation rate was averagely 164 % higher than typically designed ventilation rate, 1 AER ($min^{-1}$). Meanwhile, mechanically ventilated duck houses made 81.2 % of summer ventilation rate requirement. Therefore, it is urgent to develop a new duck house considering more structural safety as well as higher efficiency of environmental control.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.6
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• pp.21-33
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• 2015

Recently, the Korean government announced a new development plan for a large-scale greenhouse complex in reclaimed lands. Wind environments of reclaimed land are entirely different from those of inland. Many standard books for ventilation design didn't include qualitative standard for natural ventilation. In this study, natural ventilation rates were analyzed to suggest standard for ventilation design of venlo type greenhouse built on reclaimed land. CFD (Computational Fluid Dynamics) simulation models were designed according to the number of spans, wind conditions and vent openings. The wind profile at a reclaimed land was designed using ESDU (Engineering Sciences Data Unit) code. Using the designed CFD simulation model, ventilation rates were computed using mass flow rate and tracer gas decay method. Additionally computed natural ventilation rates were evaluated by comparing with ventilation requirements. As a result of this study, ventilation rates were decreased with increasing of the number of spans. Ventilation rates were linearly increased with increasing of wind speed. When the wind speed was $1.0\;m{\cdot}s^{-1}$, only side vent was open and wind direction was $45^{\circ}$, homogeneity of ventilation rate at 0~1 m height is the worst. Finally, chart for computing natural ventilation rate was suggested. The chart was expected to be used for establishing standard of ventilation design.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.2
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• pp.193-201
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• 2001

Acidic air pollutants were collected to characterize indoor air quality in a residential area in the summer. All indoor and outdoor samples were measured simultaneously using an annular denuder system(ADS) in Seoul. The data set was collected from July 26 to September 11, 1997. The mean indoor/outdoor ratios measured from this study were : 0.34 for $HNO_3$; 0.91 for $HNO_2$; 0.22 for $SO_2$; 1.34 for $NH_3$; 0.78 for $PM_{2.5}(d_p$ <2.5 $mutextrm{m}$); 0.90 for $SO_{4}^{2-}$; 0.68 for $NO_{3}^{-}$ and 0.79 for $NH_{4}^{+}$. Indoor concentrations of $HNO_3$, $SO_2$ and $PM_{2.5}$ were highly correlated with the outdoor concentrations. The relationship between indoor and outdoor air is dependent, to a large extent, on the rate of air exchange between these two environments. A tracer-gas decay technique with sulfur hexafluoride ($SF_{6}$) as a tracer gas was used to estimate the air exchange of a private home in the summer. The average air exchange rate was estimated to be 23.7 hr(sup)-1. The deposition velocities for $SO_{4}^{2-}$, $NO_{3}^{-}$ and $NH_{4}^{+}$ calculated were 0.17, 0.69 abd 0.39 cm/sec, respectively.