• Progress in Superconductivity and Cryogenics
• /
• v.20 no.4
• /
• pp.41-45
• /
• 2018

We have investigated the effect of $Y_2O_3$ nanoparticles on the pinning properties of $Y_2O_3$-doped $GdBa_2Cu_3O_{7-{\delta}}$ (GdBCO) films. Both undoped and $Y_2O_3$-doped GdBCO films were grown on $CeO_2$-buffered MgO (100) single crystal substrates by pulsed laser deposition (PLD) using KrF (${\lambda}=248nm$) laser. The $Y_2O_3$ doping contents were controlled up to ~ 2.5 area% by varying the internal angles of $Y_2O_3$ sectors put on the top surface of GdBCO target. Compared with the $Gd_2O_3$-doped GdBCO films previously reported by our group [1], the $Y_2O_3$-doped GdBCO films exhibited less severe critical temperature ($T_c$) drop and thus slightly enhanced critical current densities ($J_c$) and pinning force densities ($F_p$) at 65 K for the applied field parallel to the c-axis of the GdBCO matrix (B//c) with increasing the doping content. Below 40 K, the in-field $J_c$ and $F_p$ values of all $Y_2O_3$-doped GdBCO films exhibited higher than those of undoped GdBCO film, suggesting that $Y_2O_3$ inclusions might act as effective pinning centers.

• Journal of Korean Society on Water Environment
• /
• v.30 no.3
• /
• pp.261-268
• /
• 2014

Four clays (both natural and commercial types) mainly used in Korea were tested for removal efficiency of Microcystis spp. and ecotoxicity on Daphnia magna and Vibrio fischeri. Four clays (clay A~D) were composed of 91.9~100% of sand (0.02~0.2 mm in particle size). Clay D consisted of lager particles than other clays. Major elements of the four clays were $SiO_2$ (45.3~62.8%), $Al_2O_3$ (18.5~29.7%) and $Fe_2O_3$ (5.4~7.9%). They contained kaolinite (clay mineral), quartz, muscovite, and so on. Clay C and D contained montmorillonite, one of the clay minerals improving clay-cell aggregation. For clay A, B and C, removal efficiency of Microcystis spp. was over 60% at 2 g/L. It reached about 100% at over 5 g/L. For clay D, it was over 60% and 95~100% at 5 g/L and 20 g/L respectively. After adding clays, pH decreased. The greatest drop of pH appeared at clay C. Except for addition of 100 g/L clay C, ecotoxicity on D. magna and V. fischeri didn't appeared at all dose of clays.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.5
• /
• pp.333-338
• /
• 2022

The single jet of decane/methylcyclohexane mixed fuel that is surrogate for kerosene was injected into supercritical environment and visualized using shadowgraph technique. The injection pressure drop of the fuel jet of T_r = 0.484 was kept constant at 0.5 MPa and the experiment was conducted above the critical point of the mixed fuel, and the reduced temperatures of the chamber was changed from 1.00 to 1.23, and the reduced pressures was 1.00 and 1.38. As an index for reducing the density of jets sprayed into the supercritical environment, the brightness intensity of the post-processed jet image was observed with the internal temperature and pressure of the chamber. It was confirmed that the decrease in the brightness intensity of the jet when the temperature inside the chamber increased, and when the pressure inside the chamber was higher at the same temperature, the decrease in the brightness intensity of the jet was delayed. When the pressure inside the chamber is high, it is thought that the change in brightness intensity is delayed due to the increase in the pseudo-critical temperature of the fuel and the increase in the temperature required to reduce the density of the fuel jet.

• Journal of Fashion Business
• /
• v.10 no.5
• /
• pp.58-73
• /
• 2006

The purpose of this study was to improve of fittness and coverage rate of exporting domestic clothing to China for Chinese Adult Female. For study, It was measured 1381 female women aged between 19 and 50 who resident in Beijing and Shanghai in China. as a sample, 1360 female women was seleted for development of apparel sizing system. As for the method of this study was made of 111 items by indirect measures done during Jun. 23 $\sim$ Aug. 7, 2004. Data analysis were processed by SPSS WIN 10.0 Program was used to for technical statistical analysis, correlation analysis, factor analysis, ANOVA(t-test and F-test), duncan's multiple test. The result was as follows: Chinese Adult women's constitutional components determined by factor analysis, six components could be identified: factor 1:constitutional obesty and width size, factor 2: longistudinal body size, factor 3: shoulder form and size, factor 4: longistudinal upper body size, factor 5: under body size, factor 6: shoulder dropping. According to the Women's Wear Specifications(GB/T 1335.2-1997) by drop, body types of Chinese Adult female was classified into six types, it was Y, A, B, C and Z, D. In order, A type as standard somatotype(49.8%), B type(26.9%), Y type (18.8%), C type(2.9%). Y type had the average height and shoulder, bust girth. They were slimmer in overall terms. A type had a normal obesity and body size in height, shoulder, bust girth. They were average Chinese Women. B type had a smaller then A type. They were more obes and thick waist girth. C type had the highest obesity, the widest shoulder and bust girth, and thick waist girth. The characteristics of each body type following the body type structure factor are Y-type for slender type, A-type for standard type, B-type for slightly large type, and C-type for obese type. For each region, the Beijing area had in the order of A-type, Y-type, B-type and C-type, and the Shanghai area had in the order of A-type, B-type, Y-type and C-type.

• Journal of Mechanical Science and Technology
• /
• v.20 no.4
• /
• pp.545-553
• /
• 2006

Generally, the temperature drop under $0^{\circ}C$ on vaporizer surface creates frozen dews. This problem seems to increase as the time progress and humidity rises. In addition, the frozen dews create frost deposition. Consequently, heat transfer on vaporizer decreases because frost deposition causes adiabatic condition. Therefore, it is very important to solve this problem. This paper aims to study of the optimum design of used vaporizer at local LNG station. In this paper, experimental results were compared with numerical results. Geometries of numerical and experimental vaporizers were identical. Studied parameters of vaporizer are angle between two fins $(\Phi)$ and fin thickness $(TH_F)$. Numerical analysis results were presented through the correlations between the ice layer thickness $(TH_{ICE})$ on the vaporizer surface to the temperature distribution of inside vaporizer $(T_{IN})$, fin thickness $(TH_F)$, and angle between two fins $(\Phi)$. Numerical result shows good agreement with experimental outcome. Finally, the correlations for optimum design of vaporizer are proposed on this paper.

• Journal of Biosystems Engineering
• /
• v.14 no.2
• /
• pp.128-136
• /
• 1989

The purpose of this study was to develop a computer operated automatic drip irrigation system for application in vinyl-house cultivation. The results can be summarized as follows: 1) The T-type ice compensation wire was used to measure the temperature. The voltage level measured up to 0.02 volt was used as input to an 8-bit A/D converter. 2) A specially devised tensiometer was used to content the watering system. When the needle of the pressure gauge reaches the lower threshold position it turns on the pumping system and turns off when it reaches higher threshold position. 3) In order to use the multiple gypsum blocks for one transducer, reed relays and a D/O board were used to make the sequential switching possible. 4) It was possible to automate the trickle irrigation system for the whole growth period of vinyl-house crops with the help of microcomputer. 5) In terms of furrow irrigation, the irrigation water consumption was the smallest, 2.8 times less than conventional method of surface trickle irrigation, 3.4 times less than subsurface trickle irrigation method. 6) In terms of productivity of cucumber, there was a drop in productivity when compared to furrow irrigation method, 7.2% for surface trickle irrigation, 27.4% for subsurface irrigation method.

• Journal of the Korean Ceramic Society
• /
• v.48 no.6
• /
• pp.617-620
• /
• 2011

Thermal shock behavior of porous ceramic nozzles with various pore sizes for continuous casting process of steel was investigated in terms of physical properties and microstucture. Porous nozzle samples with a composition of $Al_2O_3$-$SiO_2$-$ZrO_2$ were fabricatedby adding various sizes of graphite as the pore forming agent. As the graphite size increased from 45~75 to 150~180 ${\mu}m$, both the resulting pore size and the flexural strength also increased. A thermal shock test was carried out at temperatures (${\Delta}$T) of 600, 700, 800, and 900$^{\circ}C$. Microstructure analysis revealed a small number of cracks on the sample with the largest mean pore size of 22.32 ${\mu}m$. In addition, increasing the pore size led to a smaller decrease in both pressure drop and elastic modulus. In conclusion, controlling the pore size can enhance thermal shock behavior.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.1083-1090
• /
• 2005

Repeated ribs are used on heat exchange surfaces to promote turbulence and enhance convective heat transfer. Applications include fuel rods of gas-cooled nuclear reactors, inside cavities of turbine blades, and internal surfaces pipes used in heat exchangers. Despite the great number of literature papers, only few experimental data concern detailed distributions of friction factors and heat transfer coefficients in square channels varying the number of rough walls. This issue is tackled by investigating effects of different number of ribbed walls on heat transfer and friction characteristics in square channel. The rough wall have a 45$^{\circ}$ inclined square rib. Uniform heat flux is maintained on whole inner heat transfer channel area. The heat transfer coefficient and friction factor values increase with increasing the number of rough walls.

• Journal of Fisheries and Marine Sciences Education
• /
• v.5 no.2
• /
• pp.119-127
• /
• 1993

This work studies for heat transfer and pressure drop performance of integral inner and outer fin tubes, designed to enhance the heat transfer performance of smooth tubes for in recipro and turbo refrigerator or high performance compact heat exchangers. Eight different inner spiral fin copper tubes with integral fin at outside surfaces were employed to improve boiling heat transfer coeffcient. For comparison, tests were made using a plain tube having the inside diameter and an outside diameter equal to that at the root of the fins for the finned tubes. Pool boiling heat transfer is investigated experimentally and theoretically on single tube arrangement. The refrigerant evaporates at a saturation state of 1 bar on the outside tube surface heated by hot water. The refrigerant R11 ($CFCl_3$) was used at a pressure of $P_s=1bar$ as a convenient test fluid with a boiling temperature of $T_s=23.6^{\circ}C$. The observed heat transfer enhancement of boiling for finned tubes significantly exceeded that to be expected on grounds of increased area. The maximum Vapor - side enhancement(i.e., vapor - side heat transfer coefficient of finned tube/vapor - side coefficient for plain tube) was found to be around 4 at 1299fpm - 30grooves tube.

• Journal of Genetic Medicine
• /
• v.17 no.2
• /
• pp.89-91
• /
• 2020

Charcot-Marie-Tooth (CMT) disease can be divided mainly into demyelination and axonopathy based on the results of the electrophysiological study. Mitofusin 2, encoded by MFN2 gene, has a crucial role in the fusion of mitochondria, which is known to associate with CMT type 2A as one of the axonal forms. We describe a 44-year-old man with progressive weakness on bilateral legs after noticing foot drop in his early teen. When we examined him at 45 years of age, he presented atrophy on entire legs and with distal muscle weakness on limbs. The nerve conduction study revealed severely decreased amplitude on motor nerve ranging from 0.2 to 4.5 mV, while conduction velocity remained more than 30.4 m/s. The whole-exome sequencing revealed a novel variant c.2228G>T in MFN2 by efficient genetic analysis tool, MutationDistiller. This report will not only expand the mutation spectrum of CMT2A but also introduce a time-saving genetic analysis tool.