• Journal of Microbiology and Biotechnology
• /
• 제20권1호
• /
• pp.187-192
• /
• 2010

In order to monitor the possibility of horizontal gene transfer between transgenic rice and microorganisms in a paddy rice field, the gene flow from a bifunctional fusion (TPSP) rice containing trehalose-6-phosphate synthase and phosphatase to microorganisms in soils was investigated. The soil samples collected from the paddy rice field during June 2004 to March 2006 were investigated by multiplex PCR, Southern hybridization, and amplified fragment length polymorphism (AFLP). The TPSP gene from soil genomic DNAs was not detected by PCR. Soil genomic DNAs did not show homologies on the Southern blotting data, indicating that gene transfer did not occur during the last two years in the paddy rice field. In addition, the AFLP band patterns produced by soil genomic DNAs from both transgenic and non-transgenic rice fields appeared similar to each other when analyzed by the NTSYSpc program. Thus, these data suggest that transgenic rice does not give a significant impact on the communities of soil microorganisms, although long-term observation may be needed.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2005년도 동계학술발표대회 논문집
• /
• pp.256-261
• /
• 2005

In the present experimental study, condensation heat transfer coefficients between R404A and R152a flow in a horizontal smooth tube were compared. The outer and inner diameters of the tube were 9.52 mm and 7.55 mm, respectively, and the heated length was 1045 mm. The mass flux ranged from 150 to 400 $kg/m^{2}s$ and the test section were uniformly heated from 8 to 12. $kW/m^2$. The quality range was from 0.2 to 0.8 at the saturation temperature from 27.3 to $34^{\circ}C$. Experimental condensation heat transfer coefficients increased as the quality and mass flux increased. Modified Dobson and Chato correlation reduced the mean deviation of 5.1% for R404A and 9.4% for R152a than the original correlation$^{(2)}$.

• 설비공학논문집
• /
• 제8권1호
• /
• pp.151-165
• /
• 1996

Relation between condensate retention and heat transfer performance is studied for condensation of CFC-11 on horizontal integral-fin tubes. Eight tubes with trapezoidally shaped integral fin density from 738fpm to 1654fpm and 10, 30 grooves are tested. The liquid retention angles are measured by the height gauge, and each tube is tested under static(non-condensing) condition (CFC-11, water) and under dynamic(condensing) condition (CFC-11). The analytical model predicts the amount of liquid retention on a horizontal integral-fin tubes within＋10 percent over most of the data. Average retention angle increases as both surface tension-to-density ratio($\sigma/\rho$) and fin density(fpm) increase, The tube having a fin density of 1299~1654fpm has the best heat transfer performance. The amount of surface flooding must keep below of 40 percent for best heat transfer performance at condensation. The tube having low number of fin density must be used for fluids having high values of $\sigma/\rho$(water, (TEX)$NH_3$, ect.) and the tube having high number of fin density must be used for the fluid having low values of $\sigma/\rho$(R-11, R-22, etc.)

• Journal of Advanced Marine Engineering and Technology
• /
• 제21권2호
• /
• pp.144-156
• /
• 1997

Experimental results for forced convection heat transfer of pure refrigerant and nonrefrigerant mixtures during condensing inside horizontal smooth tubes, double pipe heat exchanger of 7.5 mm ID and 4 000 mm long inside tube, are presented. Pure refrigerant R - 22 and R - 407 c, the mixture of R - 32 + R - 125 + R - 134a (23/25/52, wt %) are used as the test fluids. The ranges of parameters are $114.3{\sim}267.1 kg/(m^2 {\cdot} s)$ of mass velocity, <0$\sim$1.0 of quality. The vapor pressure, vapor temperature and tube wall temperature were measured. Using these data, the local and average heat transfer coefficients for the condensation are obtained. At the same given experimental conditions, the condensation heat transfer coefficients for NARMs R - 407c were lower than those for the pure refrigerant of R - 22. Local heat transfer characteristics for R - 407c were different from pure refrigerant R - 22. The condensaheat transfer coefficients for R - 407c and R - 22 increased with mass velocity. Based on the data a prediction method was presented for the calculation of dimensionless average heat transfer coefficient.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2007년도 동계학술발표대회 논문집
• /
• pp.241-246
• /
• 2007

The present paper dealt with an experimental study of boiling heat transfer characteristics of $CO_2$. Heat transfer coefficients of the refrigerant flow inside horizontal smooth microchannel were obtained with inner tube diameter of 0.3mm and length of 300mm. The direct electric heating method was applied for supplying the heat uniformly to the refrigerant. The experiments were conducted with $CO_2$ purity of 99.99%, at saturation temperature of $10^{\circ}C$, mass flux ranges of $300{\sim}900\;kg/m^2s$, and heat flux ranges of $15{\sim}45\;kW/m^2$. While heat transfer coefficient increased with the increase of heat flux in the low quality region, the heat transfer coefficient decreased with the increase of quality in the high quality region. The heat transfer coefficients were compared with seven existing correlations with the Gungor-Winterton's(1986) correlation gave the best prediction. A new corelation to predict the two-phase flow heat transfer coefficient was developed based on the Chen(1966) correlation. The new correlation predicted the experimental data well with a mean deviation of 9.69% and average deviation of -3.03%.

• 설비공학논문집
• /
• 제12권6호
• /
• pp.533-540
• /
• 2000

Condensation heat transfer characteristics have been investigated experimentally when a water vapor is condensed on the outside of a horizontal copper tube in a condenser. This problem is of particular interest in the design of a LiBr-water absorption system. Hydrophilic surface modification was performed to increase the wettability on the copper tube. The optimum hydrophilic treatment condition using acethylene and nitrogen as reaction gas is also studied in detail. The results obtained indicate that the optimum reaction gas ratio of acethylene to nitrogen for hydrophilic surface modification was found to be 7 : 3 for the best condensation heat transfer. In the wide ranges of coolant inlet temperatures, and coolant mass flow rates, both the condensation heat transfer rate and the condensation heat transfer coefficient of a hydrophilic copper tube are increased substantially, compared with those of a conventional copper tube used in a condenser. It is also found that the condensation heat transfer enhancement by the hydrophilic surface modification still emains even after a hundred cycles of wet/dry processes.

• 설비공학논문집
• /
• 제12권1호
• /
• pp.20-25
• /
• 2000

An experimental study on the condensation heat transfer coefficients of R-22, R-290 and R-600a inside horizontal tube was performed. Heat transfer measurements were performed for smooth tube with inside diameter of 10.07 mm and outside diameter of 12.07 mm and inner grooved tube having 75 fins whose height is 0.25 mm. This study was performed for condensation temperatures were from 308 K to 323 K, and mass velocity of $51 kg/m^2s - 250kg/m^2s$. The test results showed that the local condensation heat transfer coefficients increased as the mass flux increased, and also the effect of mass flow rate on heat transfer coefficients of R-290 was less than R-22. In addition, heat transfer coefficient of R-22 increased to a larger extent than R-290 and R-600a as the mass flow rate increased. Average condensation heat transfer coefficients of natural refrigerants were superior to that of R-22. The present results had a good agreement with Cavallini-Zecchin's correlation for smooth and inner grooved tubes.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.672-675
• /
• 1996

This paper presents algorithm including Kalman filter for transfer alignment of velocity and quaternion matching method, when master inertial navigation system is a gimbled type and slave inertial navigation system is a strapdown type on a cruising ship which is naturally in motion of horizontal axis attitude. And relative attitudes are considered on a measurement equation for quaternion matching between master INS and slave INS.

• 대한설비공학회지:설비저널
• /
• 제4권1호
• /
• pp.18-22
• /
• 1975

A simple analysis has been made of the condensation of vapor onto rivulets of condensate which are formed by non-wetting narrow Taflon strips circumferencially located in a certain interval on horizontal tubes. Heat transfer to the rivulets increased over $50\%$ above that to the Nusselt uniform thickness film. Results are directly applicable to condenser tubes in large steam condensers.

• 설비공학논문집
• /
• 제29권5호
• /
• pp.231-238
• /
• 2017

HFO refrigerants have recently come to be regarded as promising alternatives to R134a for use in turbo chillers. This study provides results from experiments evaluating the film condensation heat transfer characteristics of HFO refrigerants R1234ze(E) and R1233zd(E) on smooth horizontal laboratory tubes. The experiments were conducted at a saturation vapor temperature of $38.0^{\circ}C$ with surface sub-cooling temperatures in the range of $3{\sim}15^{\circ}C$. We observe that the film condensation heat transfer coefficient decreases as surface sub-cooling temperatures increase. In the case of laboratory tubes with a diameter of 19.05 mm, the film condensation heat transfer coefficients of R1234ze(E) and R1233zd(E) were approximately 11% and 20% lower than those of R134a, respectively. Furthermore, our investigation of the effect of tube diameter on film condensation heat transfer coefficients, demonstrates an inverse relationship where the film condensation heat transfer coefficient increases as laboratory tube diameter decreases. We propose experimental correlations of Nusselt number for R1234ze(E) and R1233zd(E), which yield a ${\pm}20%$ error band.