• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.359-363
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• 2011

In this paper, the characteristic of pressures had been analyzed with a series of shapes that are pressure probes used in supersonic wind tunnel. When a performance of supersonic wind tunnel is evaluated, the Mach number is calculated by using the ratio of static pressure in test section wall to total pressure in settling chamber. Also the flow condition can be visualized by schlieren system. However a number of limitations exist to measure pressure of test section due to high speed and boundary layer effect. Therefore a specific pressure probe is needed for evaluating flow condition in test section at a various of positions. In the paper, experiments were conducted in terms of some pitot probes and the results were compared and analyzed.

• Journal of Microbiology and Biotechnology
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• v.17 no.11
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• pp.1782-1788
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• 2007

Cellulosomes in Clostridium cellulovorans are assembled by the interaction between the repeated cohesin domains of a scaffolding protein (CbpA) and the dockerin domain of enzyme components. In this study, we determined the synergistic effects on cellulosic and hemicellulosic substrates by three different recombinant mini-cellulosomes containing either endoglucanase EngB or endoxylanase XynA bound to mini-CbpA with one cohesin domain (mini-CbpAl), two cohesins (mini-CbpA12), or four cohesins (mini-CbpAl234). The assembly of EngB or XynA with mini-CbpA increased the activity against carboxymethyl cellulose, acid-swollen cellulose, Avicel, xylan, and com fiber 1.1-1.8-fold compared with that for the corresponding enzyme alone. A most distinct improvement was shown with com fiber, a natural substrate containing xylan, arabinan, and cellulose. However, there was little difference in activity between the three different mini-cellulosomes when the cellulosomal enzyme concentration was held constant regardless of the copy number of cohesins in the cellulosome. A synergistic effect was observed when the enzyme concentration was increased to be proportional to the number of cohesins in the mini-cellulosome. The highest degree of synergy was observed with mini-CbpAl234 (1.8-fold) and then mini-CbpAl2 (1.3-fold), and the lowest synergy was observed with mini-CbpAl (1.2-fold) when Avicel was used as the substrate. As the copy number of cohesin was increased, there was more synergy. These results indicate that the clustering effect (physical enzyme proximity) of the enzyme within the mini-cellulosome is one of the important factors for efficient degradation of plant cell walls.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.1
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• pp.21-28
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• 2012

In this paper, both content analysis and Romey analysis were employed to analyze three 'General Computer' textbooks used in commerce and information high schools. The content analysis was employed to study the organization and contents of the textbooks, whereas the Romey analysis to determine the inquisitive tendency of four sections - Text, Data, Activity and Evaluation. The results from the content analysis showed that textbooks differed in the number of subsections, the number of pages in each section, and the number of concepts introduced in each section. Also, results from the Romey analysis demonstrated that the section Text in all the textbooks was written with a low level of inquisitive tendency, but also that they differed in that two other sections Data and Activity in one textbook exhibited a high level of inquisitive tendency while the other section Evaluation in two textbooks did. Using the aforementioned results, we proposed ways to improve the readability of 'General Computer' textbooks.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.12
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• pp.1004-1013
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• 2002

Turbulent carbon dioxide flows and cooling heat transfers under supercritical state in a straight duct with a square cross-section are numerically analyzed employing low Reynolds number $\kappa-\varepsilon$ model and algebraic stress model. The flow is assumed to be (quasi-incompressible. Predicted Nusselt number and friction factor are compared with the experimental data, Blasius correlation for friction factor and Dittus-Boelter correlation for Nusselt number. Computational results for the Fanning's friction factor agree well with the all Rohsenow and Choi's correlation, Liou and Hwang's experimental data and Blasius correlation. The results obtained by algebraic stress model agree more with the Liou and Hwang's experimental data, while the results obtained by low Reynolds number $\kappa-\varepsilon$ model agree more with Blasius correlation. In the computation of Nusselt number, Dittus-Boelter correlation can not exactly fit the computational results. Therefore we propose the new correlation$Nu=0.053Re^{0.73}Pr^{0.4}$for the turbulent cooling heat transfer of carbon dioxide under supercritical state.

• Journal of Korea Foundry Society
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• v.32 no.6
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• pp.261-268
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• 2012

The effects of thickness, base element and additive to inoculant on the number of eutectic cells and chill depth of thin-section gray cast iron were investigated. Meanwhile the number of eutectic cells increased by inoculation, chill depth decreased. The former decreased and the latter increased by holding the melt at the temperature range between 1,450 and $1,500^{\circ}C$. The former was more for the thinner casting with the thickness of 5 mm than the other. The result of thermal analysis coincided well with the change of macrostructure. The former increased and the latter decreased with the increased contents of carbon, silicon and the silicon content by inoculation. The former decreased and the latter increased with increased manganese content. The number of eutectic cells decreased as the amounts of rare earth and the bismuth added to this inoculant increased. With the addition of sulfur of 0.10 wt% of the weight of this inoculant, the maximum number of eutectic cells was obtained.

• Research in Community and Public Health Nursing
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• v.11 no.2
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• pp.499-512
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• 2000

The number of deliveries by cesarean section has increased internationally. However, The cesarean section rate is different by country to country. It is because each country has different social and cultural background and. practices its unique delivery policies. Hence, it is very important to understand the uniqueness that one country faces related with the cesarean section. In Korea, there have been many researches on the clinical. maternal. hospital and community factors and so on. However, few studies have attempted to reveal the physician factors in Korea because it is difficult to approach hospital records. So, in this study, the physician factors that influence the increase of cesarean section rate in Korea was investigated, and preliminary research agenda for policy establishment to keep the cesarean section rate from excessive increase was provided. In this study, all 2744 cesarean section deliveries performed by 36 physicians at the hospital was considered. and detailed delivery records of 12 months selected randomly from January 1996 to August 1998 was reviewed retrospectively. Chi-square analysis is used to examine the homogeneity of distribution of maternal, fetal, and clinical factors. In addition, multiple regression analysis is used to examine the effect of physician characteristics on the cesarean section rate. Physician characteristics as independent variable and the cesarean section rate as dependent variable was put in this analysis. Follows are the results of this study. 1) Total cesarean section rate is 34.8%. primary cesarean section rate is 12.5 % and repeated cesarean section rate is 22.3 %. Among the indications for the primary cesarean section, 15.6 % is for breech presentation. 40.2 % is for dystocia. 7.6 % is for fetal distress. and 36.6 % is for others. 2) There is positive correlation between physician's age and the cesarean section rate (p<0.001). And statistically significant correlation is found between the physician's educational attainment and the cesarean section rate (p<0.001). A physician with Ph.D degree has lower cesarean section rate than a physician with B.A only and M.A. degree (p<0.001). However. physician's gender, location of graduated university. position at the hospital, and the religious belief were not shown statistically significant relations with the cesarean section rate. 3) Among all cesarean sections in this study, only 15.4 % is performed during weekend. While 18.2 % is performed on monday only. This suggests that physicians may not prefer weekend operation of cesarean section. In addition, 86.1 % among all cesarean section operations is performed from 6 a.m. to 6 p.m. So the cesarean section rate could be related with a day of the week and a time of the day. From this results. there is a possibility that the physicians' personal comfort may influence the cesarean section rate.

• Fibers and Polymers
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• v.6 no.1
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• pp.82-88
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• 2005

We have investigated the luster of modified cross-sectional fiber fabrics as one of the essential quality estimates for clothing development. We have confirmed an objective evaluation method, and have determined the experimental luster char­acteristics of modified cross-section fibers. The cross-section of the fibers in a fabric affects the appearance of a textile. We used the image analysis method to investigate the luster to determine the critical factors influencing the appearance of modi­fied cross-section fiber fabrics. For similarly structured textiles in a component fabric, clear differences were observed in the fabric weave, density, percentage, and total area of blobs, which is image region. Color played a decisive role in the luster of the textiles, and luster was not significantly influenced by the modified cross-section fabric weave. In addition, the degree of luster did not increase in the order plain to twill to satin for modified cross-sectional fiber fabrics. All the split-type microfi­bers exhibited higher numerical luster values (percentage of pixels, and number and total area of blobs) than sea-island microfibers did. The degree of luster of the modified cross-sectional fiber fabrics was not high at specular reflection angles.

• Transactions of Materials Processing
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• v.10 no.4
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• pp.311-318
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• 2001

Porthole die extrusion has a great advantage in the forming of long hollow section tubes. It is difficult to produce long hollow section tubes with complicated section by the conventional extrusion process with a mandrel on the stem Because of the limit of the length of mandrel and the complexity of cross section. Porthole die extrusion is affected by many parameters, such as extrusion ratio, extrusion speed, die geometry, porthole number, bearing length etc. Up to now, most of studies about porthole die extrusion have been investigated by experiments or steady state FE-analysis. However, in this paper, porthole die extrusion is analysed by the unsteady state 3D FE-simulation. And the result of unsteady state analysis is compared with the experimental result. Also, the surface state of extruded tubes are examined for the various process conditions.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.12 no.3
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• pp.13-24
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• 2004

It is easier to view flow visualization by using a water tunnel rather than a smoke wind tunnel because of low speed at same Reynolds number. Using a water tunnel also produces more definite flow visualization by the use of various color dyes. The flow uniformity in test section is very significant for accuracy of the test because most flow experiments elicit results through the installation of a model in uniform flow. The purpose of small-size desktop-type water tunnel is not to produce quantitative measurements, but rather to give a visualization of the fluid flow phenomenon. However, uniformity in the test section affects the accuracy of the results. Accordingly, this research estimates uniformity in a water tunnel test section by using the commercially available CFD code FLUENT. Results of the CFD analysis show that the flow uniformity of the test section is good.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.6
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• pp.583-592
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• 2010

Equations of motion of thin-walled composite H-type cross-section beams exposed to concentrated harmonic and non-harmonic time-dependent external excitations, incorporating a number of nonclassical effects of transverse shear, primary and secondary warping, and anisotropy of constituent materials are derived. The forced vibration response characteristics of a composite H-type cross-section beam exhibiting the circumferentially asymmetric stiffness(CAS) configuration are exploited in connection with the structural bending-torsion coupling resulting from directional properties of fiber reinforced composite materials.