• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.11
• /
• pp.914-921
• /
• 2017

The experimental research on a high-altitude environment simulation of space launch vehicle is important for securing independent technologies with launching space vehicles and completing missions. This study selected an altitude of 65 km for the experiment environment where it exceeded Mach number of 6 after the launch of Korean Space Launch Vehicle(KSLV-II). Shock tunnel was used to replicate the flight condition. After flow establishment, in order to confirm aerodynamic characteristics and normal and oblique shockwaves, the flow verification was carried out by measuring stagnation pressure and heat flux of a forebody model, and shockwave stand-off distance of a hemispherical model. In addition, a shock-free technique to recover free-stream condition has been developed and verified. From the results of the three verification tests, it was confirmed that the flow was replicated with the error of about ${\pm}3%$. The error between the slope angle of inclined shockwave of the scaled down transition section model using the shock-free shape and the slope angle of the horizontal plate model, and between the theoretical and the experimental value of the static pressure of the model were confirmed to be 2% and 1%, respectively. As a result, the efficiency of the shockwave cancellation technique has been verified.

• The Korean Journal of Petroleum Geology
• /
• v.4 no.1_2 s.5
• /
• pp.20-26
• /
• 1996

In order to uncover the subsurface geological structure in the southwestern rim of the Ogcheon Fold Belt including the Cretaceous Neungju Sedimentary Basin, we analysed and interpreted the aeromagnetic anomalies over the region. The study area belongs to Muan-gun, Yeongam-gun, Gangjin-gun, Jangheung-gun, and eastem Haenam-gun. From the qualitative analysis and quantitative modeling of the reduced-to-the-pole magnetic anomalies, following things are revealed or suggested; Even though the porphyry of higher susceptibility is not crop out in the Donggang Myeon in the northwestern part of the study area, it is supposed to have intruded the Precambrian gneiss and the Cretaceous Bulgugsa granite of lower susceptibility. Two-dimemsional modeling of profile data across the sedimentary basin of Neungiu Group reveals that the northern part of the basin is deeper than the southern part, and that the maximum depth of the basin is supposed to be $3\cal{km}$ below the surface. The western flank of the basin bottom is steeper than the eastern flank. The high susceptibility value of the Neungju Group sedimentary rocks indicates that the rocks comprises large amount of volcanic materials. This fact implies that it is hard to expect hydrocarbon reservoir in the sedimentary rocks of the Neungiu Basin.

• Journal of Biomedical Engineering Research
• /
• v.24 no.1
• /
• pp.1-8
• /
• 2003

The job of long distance driving is likely to be fatiguing and requires long period alertness and attention, which make considerable demands of the driver. Driving fatigue contributes to driver related with accidents and fatalities. In this study, we investigated the relationship between the number of hours of driving and driving fatigue using heart rate variability(HRV) signal. With a more traditional measure of overall variability (standard deviation, mean, spectral values of heart rate). Nonlinear characteristics of HRV signal were analyzed using Approximate Entropy (ApEn) and Poincare plot. Five subjects drive the four passenger vehicle twice. All experiment number was 40. The test route was about 300Km continuous long highway circuit and driving time was about 3 hours. During the driving, measures of electrocardiogram(ECG) were performed at intervals of 30min. HRV signal, derived from the ECG, was analyzed using time, frequency domain parameters and nonlinear characteristic. The significance of differences on the response to driving fatigue was determined by Student's t-test. Differences were considered significant when a p value < 0.05 was observed. In the results, mean heart rate(HRmean) decreased consistently with driving time, standard deviation of RR intervals(SDRR), standard deviation of the successive difference of the RR intervals(SDSD) increased until 90min. Hereafter, they were almost unchanging until the end of the test. Normalized low frequency component $(LF_{norm})$, ratio of low to high frequency component (LF/HF) increased. We used the Approximate Entropy(ApEn), Poincare plot method to describe the nonlinear characteristics of HRV signal. Nonlinear characteristics of HRV signals decreased with driving time. Statistical significant is appeared after 60 min in all parameters.

• Microbiology and Biotechnology Letters
• /
• v.36 no.1
• /
• pp.49-54
• /
• 2008

The gene encoding human pancreatic pro-carboxypeptidase B (CPB) was cloned and fused to Saccharomyces cerevisiae mating factor alpha-1 secretion signal $(MF{\alpha}1)$, in which the transcription of $MF{\alpha}1$-pro-CPB was under the control of GAL10 promoter. The constructed plasmid $pY{\alpha}$-hproCPB(7.72 kb) was transformed into S. cerevisiae 2805. The recombinant human pro-CPB (hproCPB) was successfully expressed in S. cerevisiae after induction of galactose, and could be secreted into the culture medium. By analyses of SDS-PAGE and western blotting, the molecular weight of the purified hproCPB was estimated to be a 45.9kDa. The activity of extracellular hCPB after removal of pro-region by trypsin treatment reached about 10.16 unit/ml at batch culture of S. cerevisiae $2805/pY{\alpha}$-hproCPB for 60 h. Also, the Km value of partially purified recombinant hCPB is about 0.43 mM.

• Applied Biological Chemistry
• /
• v.38 no.1
• /
• pp.42-48
• /
• 1995

The experiment was carried out to purify and to investigate the properties of the cyclodextrinase produced from Bacillus megaterium KFCC 11855. The enzyme was partially purified with $(NH_4)_2SO_4$ and chromatography on DEAE-trisacryl, Ultrogel AcA 34, DEAE-trisacryl and Ultrogel HA. The optimum temperature and pH of the purified enzyme were $60^{\circ}C$ and 6.0, respectively. The enzyme was stable at the temperature of $45^{\circ}C$ below and at the pH range of $6.0{\sim}9.0$, respectively. The Km value for ${\gamma}-cyclodextrin$ was 0.903 mM. The enzyme activity was increased by $Mg^{2+}$ and $Mn^{2+}$, but decreased by $Hg^{2+}$ and $Cu^{2+}$. The enzyme degraded ${\gamma}-cyclodextrin$ but not ${\alpha}-cyclodextrin$. The degree of ${\beta}-CD$ degradation by the enzyme was very low. The decomposed products of ${\gamma}-cyclodextrin$ by the enzyme were mainly glucose, maltose and a little amount of maltotriose.

• Microbiology and Biotechnology Letters
• /
• v.9 no.4
• /
• pp.197-205
• /
• 1981

Penicillin amidase of Bacillus megaterium was recovered from the fermentation broth by adsorption on celite and immobilized by entrapping the adsorbed enzyme in acrylamide gel. The operational stability in column reactor was greatly increased by entrappment as compared with that of without entrappment. The optimum pH of the immobilized enzyme was 8.7 with broader activity profile than that of the free enzyme, while the most stable pH range appeared to be between pH 7.5 and 8.0. The optimum temperature was shifted to 5$0^{\circ}C$ from 45$^{\circ}C$ for the soluble enzyme. The values of Km and the inhibition constants for 6-APA( $K_{ia}$ ) and phenylacetic acid ( $K_{ip}$ ), were 4.55 mM, 36.5mM, and 10.5mM, respectively. No significant internal pore diffusion limitation was found since the value of effectiveness factor was 0.95. The operational half life in a column reactor at pH 8.0 was 6.8 days at 4$0^{\circ}C$ and 47 days at 3$0^{\circ}C$, whereas that of without entrappment was only 1 day and 4 days, respectively. The performance of a batch and a column reactor was also discussed with respect to the productivity. The results demonstrated that the entrappment of an adsorbed enzyme for the enhancement of the operational stability of the immobilized enzyme was useful especially when an extracellular enzyme was used.

• Journal of Astronomy and Space Sciences
• /
• v.25 no.4
• /
• pp.383-394
• /
• 2008

We examine geoeffective directional parameters of coronal mass ejections (CMEs). We select 30 front-side halo CMEs from SOHO LASCO CMEs whose speed is larger than 1000km/s and longitude is less than ${\pm}30^{\circ}$. These are thought to be the most plausible candidate of geoeffective CMEs. We examine the relation between CMEs directional parameters (Earthward direction, eccentricity, ${\Delta}$ distance and central angle parameter) and the minimum value of the Dst index. We have found that the Earthward direction parameter has a good correlation with the Dst index, the eccentricity parameter has a much better correlation with the Dst index. The bo distance and central angle parameter has a poor correlation with the Dst index. It's, however, well correlated with the Dst index in very strong geomagnetic storms. Most of CMEs causing very strong storms (Dst ${\leq}$-200nT) are found to have large Earthward direction parameter $({\geq}0.6)$, small eccentricity, bo distance and central angle parameters $(E{\leq}0.4,\;{\Delta}X\;and\;sin\;{\theta}{\leq}0.2)$. These directional parameters are very important parameters that control the geoeffectiveness of very fast front-side halo CMEs.

• Current Research on Agriculture and Life Sciences
• /
• v.9
• /
• pp.51-59
• /
• 1991

This study was conducted to understand browning characteristics of Chinese Chestnut during processing and storage. For this, the isolation and identification of polyphenolic compounds and the biochemical characteristics of polyphenol oxidase(PPO) were investigated. The content of total phenol was $6.5{\mu}g/g$ and it was consisted of ferulic acid, caffeic acid, synapic acid, p-coumaric acid, gallic acid and salicylic acid in order. PPO was purified 11.7 fold through ammonium sulfate fractionation, DEAE-cellulose column chromatography and Sephadex G-200 column chromatography. Purified enzyme showed single protein and activity band by polyacrylamide gel electrophoresis. The optimum pH and temperature of PPO were 5.9 and $45^{\circ}C$, respectively. The activity of PPO was lost 93% by exposing at $80^{\circ}C$ for 15minutes. $Mg^{{+}{+}}$, $Ca^{{+}{+}}$, $Zn^{{+}{+}}$ increased the activity of PPO, but $Fe^{{+}{+}}$, $K^+$, $Hg^{{+}{+}}$ inhibited PPO at 10mM concentration. L-ascorbic acid, thiourea, sodium chloride and L-cysteine were effective inhibitors of PPO. The activity of PPO was higher for o-diphenols than other polyphenols. The Km value of PPO for catechol was 5mM.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.21 no.2
• /
• pp.71-79
• /
• 1988

For the purpose of producing low salt fermented anchovy by accelerated method with a strong proteolytic bacteria, in this study, a strong proteolytic bacterium was isolated from low salt fermented anchovy and its bacteriological characteristics and properties of protease were experimented. The results obtained were as fellows : three proteolytic bacteria, Aeromonas anaerogenes Barillus subtilis and Staphylococcus saprophyticus were isolated from low salt fermented anchovy($4\%\;of\;salt,\;4\%\;of\;KCl,\;0.5\%\;of\;lactic\;acid,\;6\%$of sorbitol and $4\%$ of alcohol extract of red pepper) after 40 days fermentation. Among these strains, which grow best at $30^{\circ}C$, pH 7.0, B. subtilis was found the best proteolytic strain and benefit for industrial use as shown $0.95\;hr^{-1}$ of specific growth rate, $89{\mu}g-Tyr/hr.ml$ of maximum activity after 12 hrs culture in TPY broth. The protease produced by by B. subtilis showed maximum activity at $35^{\circ}C$, pH 7.0, and molecular weight was estimated to be 23,000 by Sephadex G-100 filtration, and it was supposed to be a kind of metal chelator sensitive neutral protease from the results of strong sensitivity against EDTA, o-phenanthroline and metal ions such as $Cu^{2+},\;Ni^{2+},\;Fe^{2+}.Km$ value of that by method of Lineweaver-Burk was determinded to be $0.73\%$ for casein as a substrate.

• The Korean Journal of Physiology
• /
• v.22 no.2
• /
• pp.281-293
• /
• 1988

The effect of pH on the rate of PAH uptake was studied in rabbit renal basolateral membrane vesicles (BLMV) and brush border membrane vesicles (BBMV). In the absence of Na in incubation medium, a decrease in external $pH(pH_0)$ led to an increase in probenecid-sensitive PAH uptake by BLMV. In the presence of Na, the probenecid-sensitive PAH uptake was unaltered when the $pH_0$ decreased from 8.0 to 6.0 but further decrease in $pH_0$ to 5.5 increased significantly the uptake. The probenecid-sensitive PAH uptake was not affected by an alteration in pH per se in the absence of a pH gradient with or without the presence of Na. However, the presence of Na stimulated the probenecid-sensitive PAH uptake in all pH ranges tested over that measured in the absence of Na. A similar pattern of pH dependence on the PAH uptake was observed in BBMV but the presence of Na did not alter the probenecid-sensitive PAH uptake in the presence and absence of a pH gradient. Kinetic analysis for BLMV showed that Na or pH gradient increased Vmax of the probenecid-sensitive PAH uptake without a change in Km value. These results suggest that PAH is transported by $OH^-/PAH$ exchange process in the luminal membrane, but the pH dependence in the BLMV is not unequivocally consistent with an anion exchange process. The PAH transport is dependent on Na in BLMV but not in BBMV.