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조종수,강병국,양재경,박종열,김윤근 진주산업대학교 농업기술연구소 2000 農業技術硏究所報 Vol.13 No.-
This paper was carried out to analyze the variation of composition of seed oil with storage periods. Difference of content of crude fat in fresh-cut seed and one year storage seed is not detected but in pentadecanoic acid, acid value, iodine value and peroxide value in one year storage seed have lower than those of the fresh-cut seed. Linoleic acid and oleic acid were high among of total fatty acid in fresh-cut seed but moiety of linolenic acid and icosanoic acid was low otherwise that of palmitic acid and oleic acid is increased in one year storge. In neutral lipid, capric and mytistic acid were high in fresh-cut, oleic acid, palmitic acid and linoleic acid were increased after one year storge. In glycolipid, the lauric acid and linoleic acid were high in fresh-cut seed, the palmitic acid was increased, otherwise, linolenic acid was decreased after one year storge. In phospholipid, palmitic acid and unknown part were high in fresh-cut seed, palmitic acid, oleic acid and linolenic acid were increased after one year storge.
MEASUREMENT OF THE SINGLE AND TWO PHASE FLOW USING A NEWLY DEVELOPED AVERAGE BIDIRECTIONAL FLOW TUBE
Yun, Byong-Jo,Euh, Dong-Jin,Kang, Kyunc-Ho,Song, Chul-Hwa,Baek, Won-Pil Korean Nuclear Society 2005 Nuclear Engineering and Technology Vol.37 No.6
A new instrument, an average BDFT (Birectional Flow Tube), was proposed to measure the flow rate in single and two phase flows. Its working principle is similar to that of the Pilot tube, wherein the dynamic pressure is measured. In an average BDFT, the pressure measured at the front of the flow tube is equal to the total pressure, while that measured at the rear tube is slightly less than the static pressure of the flow field due to the suction effect downstream. The proposed instrument was tested in air/water vertical and horizontal test sections with an inner diameter of 0.08m. The tests were performed primarily in single phase water and air flow conditions to obtain the amplification factor(k) of the flow tube in the vertical and horizontal test sections. Tests were also performed in air/water vertical two phase flow conditions in which the flow regimes were bubbly, slug, and churn turbulent flows. In order to calculate the phasic mass flow rates from the measured differential pressure, the Chexal drift-flux correlation and a momentum exchange factor between the two phases were introduced. The test results show that the proposed instrument with a combination of the measured void fraction, Chexal drift-flux correlation, and Bosio & Malnes' momentum exchange model could predict the phasic mass flow rates within a $15\%$ error. A new momentum exchange model was also proposed from the present data and its implementation provides a $5\%$ improvement to the measured mass flow rate when compared to that with the Bosio & Malnes' model.
Yun, Byong-Jo,Bae, Byoung-Uhn,Euh, Dong-Jin,Song, Chul-Hwa Elsevier 2010 Nuclear engineering and design Vol.240 No.12
<P><B>Abstract</B></P><P>As a series of subcooling boiling flow tests, local two-phase flow parameters were obtained at SUBO (subcooled boiling) test facility under steam–water flow conditions. The test section is a vertical annulus of which the axial length is 4.165m with a heater rod at the center of a channel. The inner and outer diameters of the test section and the heater rod are 35.5mm and 9.98mm, respectively. The test was performed by a two-stage approach. Stage-I for the measurement of local bubble parameters has been already done (<ce:cross-ref refid='bib26'>Yun et al., 2009</ce:cross-ref>). The present work focused on the stage-II test for the measurement of local liquid parameters such as a local liquid velocity and a liquid temperature for a given flow condition of stage-I. A total of six test cases were chosen by following the test matrix of stage-I. The flow conditions are in the range of the heat flux of 370–563kW/m<SUP>2</SUP>, mass flux of 1110–2100kg/(m<SUP>2</SUP>s) and inlet subcooling of 19–31°C at pressure condition of 0.15–0.2MPa. From the test, local liquid parameters were measured at 6 elevations along the test section and 11 radial locations of each elevation in addition to the previously obtained local void fraction, interfacial area concentration, Sauter mean diameter and bubble velocity. The present subcooled boiling (SUBO) data completes a data set for use as a benchmark, validation and model development of the Computational Fluid Dynamics (CFD) codes or existing safety analysis codes.</P>
Yun, Byong-Jo,Kwon, Tae-Soon,Song, Chul-Hwa,Euh, Dong-Jin,Park, Jong-Kyun,Cho, Hyoung-Kyu,Park, Goon-Cherl Korean Nuclear Society 2001 Nuclear Engineering and Technology Vol.33 No.3
Direct ECC bypass phenomena that occur in a reactor vessel downcomer with a Direct Vessel Injection (DVI) system during the reflood phase of a Large Break Loss-of-Coolant Accident (LBLOCA) are experimentally investigated using a transparent l/7.5 scaled down test facility of the Upper Plenum Test Facility (UPTF). A series of separate effect tests are peformed in order to investigate the mechanisms of direct ECC bypass and to find out its scaling parameters. Various flow regimes and phasic distribution in downcomer are identified and mapped, and the fraction of direct ECC bypass is measured under a wide range of air and water injection conditions. From the counterpart test of the UPTF Test 21-D, the dimensionless gas velocity ( $j^{*}$$_{g,eff}$) is derived experimentally, which is believed to be a major scaling parameter for the fraction of direct ECC bypass. And it is found out that the direct ECC bypass is greatly affected by the spreading width of ECC water film and the geometric configuration of the downcomer.r.
Flow Structure of Subcooled Boiling Water Flow in a Subchannel of 3×3 Rod Bundles
YUN, Byong-Jo,PARK, Goon-Cherl,JULIA, J. Enrique,HIBIKI, Takashi Atomic Energy Society of Japan 2008 Journal of nuclear science and technology Vol.45 No.5
<P>In this paper, the interfacial flow structure of subcooled water boiling flow in a subchannel of 3×3 rod bundles is presented. The 9 rods are positioned in a quadrangular assembly with a rod diameter of 8.2 mm and a pitch distance of 16.6 mm. Local void fraction, interfacial area concentration, interfacial velocity, Sauter mean diameter, and liquid velocity have been measured using a conductivity probe and a Pitot tube in 20 locations inside one of the subchannels. A total of 53 flow conditions have been considered in the experimental dataset at atmospheric pressure conditions with a mass flow rate, heat flux, inlet temperature, and subcooled temperature ranges of 250–522 kg/m<SUP>2</SUP> s, 25–185 kW/m<SUP>2</SUP>, 96.6–104.9°C, and 2–11 K, respectively. The dataset has been used to analyze the effect of the heat flux and mass flow rate on the local flow parameters. In addition, the area-averaged data integrated over the whole subchannel have been used to validate some of the distribution parameter and drift velocity constitutive equations and interfacial area concentration correlations most used in the literature.</P>
MEASUREMENT OF THE SINGLE AND TWO PHASEFLOW USING A NEWLY DEVELOPED AVERAGEBIDIRECTIONAL FLOW TUBE
BYONG JO YUN,백원필,송철화,DONG JIN EUH,KYUNG HO KANG 한국원자력학회 2005 Nuclear Engineering and Technology Vol.37 No.6
A new instrument, an average BDFT (Birectional Flow Tube), was proposed to measure the flow rate in single and two phase flows. Its working principle is similar to that of the Pitot tube, wherein the dynamic pressure is measured. In an average BDFT, the pressure measured at the front of the flow tube is equal to the total pressure, while that measured at the rear tube is slightly less than the static pressure of the flow field due to the suction effect downstream. The proposed instrument was tested in air/water vertical and horizontal test sections with an inner diameter of 0.08m. The tests were performed primarily in single phase water and air flow conditions to obtain the amplification factor(k) of the flow tube in the vertical and horizontal test sections. Tests were also performed in air/water vertical two phase flow conditions in which the flow regimes were bubbly, slug, and churn turbulent flows. In order to calculate the phasic mass flow rates from the measured differential pressure, the Chexal drift-flux correlation and a momentum exchange factor between the two phases were introduced. The test results show that the proposed instrument with a combination of the measured void fraction, Chexal drift-flux correlation, and Bosio & Malnes’ momentum exchange model could predict the phasic mass flow rates within a 15% error. A new momentum exchange model was also proposed from the present data and its implementation provides a 5% improvement to the measured mass flow rate when compared to that with the Bosio & Malnes’ model.
단상 및 이상유동 유량 계측을 위한 평균 양방향 유동 튜브 개발
윤병조(Byong-Jo Yun),강경호(Kyong-Ho Kang),어동진(Dong-Jin Euh),백원필(Won-Pil Baek) 한국유체기계학회 2004 유체기계 연구개발 발표회 논문집 Vol.- No.-
Average Bi-directional flow tube was suggested to measure single and two phase flow rate. Its working principle is similar with Pitot tube, however, it makes it possible to eliminate the cooling system which is normally needed to prevent from flashing in the pressure impulse line of Pitot tube when it is used in the depressurization condition. The suggested instrumentation was tested in the air-water vertical test section which has 80㎜ inner diameter and 10m length. The flow tube was installed at 120 of L/D from inlet of test section. From the test, single air and water flow rate was measured successfully. For the emasurement of two phase flow rate, Chexal drift-flux correlation was used. In the test a new correlation of momentum exchange factor was suggested. The test result shows that the suggested instrumentation using the measured void fraction and Chexal drift-flux correlation can predict the mass flow rates within 10% error of measured data.
Jo, Jong Chull,Jeong, Jae Jun,Yun, Byong Jo,Kim, Jongkap Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.1
This paper presents a numerical prediction of the transient hydraulic loads acting on the tubes and external supports of a pressurized water reactor (PWR) steam generator (SG) during blowdown following a sudden feedwater line break (FWLB). A simplified SG model was used to easily demonstrate the prediction. The blowdown discharge flow was treated as a flashing flow to realistically simulate the transient flow fields inside the SG and the connected broken feedwater pipe. The effects of the SG initial pressure or the broken feedwater pipe length on the intensities or magnitudes of transient hydraulic loads were investigated. Then predictions of the decompression pressure wave-induced impulsive pressure differential loads on SG tubes and the transient blowdown loads on SG external supports were demonstrated and the general aspects of transient responses of such transient hydraulic loads to the FWLB were discussed.