• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.3
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• pp.230-240
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• 2009

The ESCORT model is applied at Mokpo coastal zone to analyze the effect of fresh water discharge released from the gates of the Youngsan River sea-dyke. Applicability and validity of both 2-D and 3-D hydrodynamic modules could be guaranteed by simulating hydrodynamic feature with ebb dominance characteristics. Then, effects of the released discharge on the hydrodynamics are investigated. And analysis of the effects on diffusion phenomena show that 3-D model is essential for such diffusion modelling. Moreover, vertical salinity distributions near the gates are examined, and the influence range of fresh water is also estimated, which shows that dilution of fresh water is going on slowly because of poor flushing.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1124-1131
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• 2011

This study performed the prediction about the indoor contaminant's diffusion characteristics which can be affected by the mechanical ventilation system on a training ship. The results are as followings. It is clear that the contaminants are spread to most of the indoors, regardless of the contamination beginning zone. About 65~100 minutes later, the contaminant densities of whole indoor zones are evaluated as clean. Comparing the contamination beginning zone being located at higher deck(scenario A) to the contamination beginning zone being located at lower deck(scenario B), although the contaminant density by scenario A is 10 times higher than that by scenario B, the number of contaminated zones are 50% less. The contaminant densities are evaluated as to be rapidly decreased when the outside air induction ratio against design volume is over 75%.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.847-864
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• 1988

The main purpose of this study is to investigate the local velocity acceleration in a boundary layer diffusion flame over a flat plate. In order to know the effect of separation on the local velocity acceleration, two typical cases, flows with and without separation, are considered. For these cases, flow visualization using paraffine smoke tracers has been made. Mean velocity and r.m.s. value of fluctuating velocity are measured by using a laser Doppler velocimeter. In addition, measurements of time-mean concentration and time-mean temperature have been made. Time-mean density profiles have been obtained from the data of concentration and temperature. The obtained results are summarized as follows : (1) In the case without separation, the local velocity acceleration is clearly observed near the visible flame zone for all flow conditions. On the while, in the case with serration, the local velocity acceleration is observed only at low free stream velocity and high fuel injection velocity. As increasing the free stream velocity or decreasing the fuel injection velocity, it is not distinctly observed in the mean velocity profile. (2) The r.m.s. value of fluctuating velocity is significantly decreased by combustion in the case with separation. But in the case without separation, the r.m.s. value is increased near the visible flame zone in comparison with cold flow. In both cases, the peak value of r.m.s. appeared just at the visible flame zone, where the mean velocity gradient is not too high.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1109-1115
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• 2004

The objective of this study is to elucidate what governs delayed hydride cracking (DHC) in Zr-2.5Nb tubes by correlating the striation spacings with DHCV(DHC Velocity). To this end, DHC tests were conducted on the compact tension specimens taken from the Zr-2.5Nb tubes at different temperatures ranging from 100 to $300^{\circ}C$ with a 3 to 6 data set at each test conditions. The compact tension specimens were electrolytically charged with 27 to 87 ppm H before DHC tests. After DHC tests, the striation spacings and DHCV were determined with the increasing the test temperature and yield strength. The striation spacing and DHCV increased as a function of yield $strength^2$ and the temperature. Since the plastic zone size ahead of the crack tip can be represented by ${\sim}(K_{IH}/{\sigma}_{Y})^2$, we conclude that the striation spacing is governed by the plastic zone size which in turn determines a gradient of hydrogen concentration at the crack tip. The relationship between the plastic zone size and the striation spacing was validated through a complimentary experiment using double cantilever beam specimens. Two main factors to govern DHCV of Zr-2.5Nb tubes are concluded to be hydrogen diffusion and a hydrogen concentration gradient at the crack tip that are controlled by temperature and yield strength, respectively. The activation energy of DHCV in the Zr-2.5Nb tubes is discussed on the basis of temperature dependency of hydrogen diffusion and the striation spacing.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.1
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• pp.38-44
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• 2006

A simple and easy modification of AST by disk diffusion was tested for the detection of induced clindamycin resistant Staphylococci and their antimicrobial susceptibility at the same time. The incidence of inducible clindamycin resistant staphylococci in blood culture and their MIC characterization at Seoul National University Hospital was analyzed by an AST contained disk approximation test (D-zone test) and Etest, respectively. Of the total 309 staphylococcal isolates, 139 (45%) isolates presented constitutive resistance to ERY and CLI (ERY-R, CLI-R phenotype), and 59 were ERY-I/R and CLI-S phenotypes. Of the 59 isolates, 19 (32%) isolates were inducible resistant to CLI. The incidence was higher in S. aureus (66.7%) than coagulase-negative staphylococci (CNS, 26.0%). Especially, methicillin-resistant staphylococci (MRSA, 100%; MRCNS, 45.5%) presented higher inducibility than methicillin susceptible (MSSA, 50%; MSCNS, 20%). For most of the inducible clindamycin resistant staphylococci (15 of 19 isolates), their ERY MIC were high (>$128_{\mu}g/mL$) and were methicillin resistant. The remaining 4 isolates were methicillin susceptible and their ERY MIC were of intermediate concentrations ($1-4_{\mu}g/mL$). We concluded that suscetibility testing of staphylococci, especially methicillin resistant, should include the D-zone test.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.22 no.1
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• pp.100-107
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• 2009

Objective : The purpose of this study is to investigate the antibacterial activity of Saussurea lappa for the applications of herb-based extracts to both cosmetic and medicinal industries. Methods : Antibacterial activity of ethanol extract of Saussutes lappa (ESL) was assessed using agar diffusion and broth dilution methods, and determined by whether clear zone was formed around paper disc and in terms of the size (mm) of clear zone, Results : ESL provided activity against Staphylococcus aureus KCTC 1927 in concentration of 1 mg/ml with an clear zone of 16 mm, and showed an activity against Staphylococcus epidermids KCTC 1917 in concentration of 1 mg/ml with an clear zone of 18mm. Moreover, the minimum inhibitory concentration (MIC) of ESL against S. sureus and S. epidermidls were 1 mg/ml for both bacterial species. However, ESL showed no growth inhibition against Pseudomonas aeruginosa KCTC 12513, Enterobactet aerogenes KCTC 2190, Escherichia coli KCTC 2571, Salmonella typhimurium KCTC 1925 and Propionibacterium acnes KCCM 41747. Conclusions : Antibacterial activity of ESL against Staphylococcus sureus and Staphylococcus epidermids causing eye and skin diseases was proved. The result suggest that ESL may be useful as a natural preservative on behalf of synthetic preservatives.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.945-948
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• 2006

Chloride penetration into concrete is a hot issue of concern all over the world, notwithstanding, very few attempts have been conducted to explore the effect of cracks on choride penetration. Cracks provoke to lose a main function of watertightness of concrete and lead to reduce the service life of concrete. For this reason, it is necessary to define a critical crack width to prevent a quick chloride penetration through crack. In this study, experiment is focused on establishing a critical crack width in terms of chloride penetration. Concrete specimens with different crack widths I crack lengths have been subjected to rapid chloride migration testing. In a side of analytical solution, a simple approach to quantify the chloride diffusion coefficient of only crack zone excluding sound concrete was proposed. The result clearly showed a critical crack width of 0.03 mm. Based on the experimental results, a phenomenological model was proposed to explain the meaning of critical crack width in practical engineering. In this model, cracked concrete zone was divided into three zones. These zones corresponded to a wide crack, a zone with micro-cracks and an uncracked zone.

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.134-140
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• 1992

The purpose of this study was to investigate the antibacterial effect of zinc oxide eugenol(ZOE), zinc phosphate cement(ZPC), glass ionomer cement, resin, and Vitapex to S. muntans, S. sanguis, S. fecalis and E. coli by agar diffusion method. Four wells were punctured in mitis-salivarius agar plate per each group and each wells were filled with restorative matetials. The width of inhibition zones produced in mitis - salivarius agar were measured as the parameter of the antibacterial effect after 16 hours and 40 hours. In S. mutans and S. sanguis, the largest inhibition zone was produced on ZOE, followed by glass ionomer cement, and ZPC. Inhibition zones was not observed in resin and Vitapex. In S. fecalis, ZOE and glass ionomer cement showed wider inhibition zone than ZPC. In E. coli, ZOE showed wider inhibition zone than ZPC, but no inhibition zone was observed on glass ionomer cement.

• Korean Journal of Veterinary Research
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• v.5 no.1
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• pp.1-16
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• 1965

I. A Comparison of Sodium Sulfate Precipitation and Zone(Paper, Agar) Electrophoresis; Many kinds of techniques have been used for fractionating serum proteins. In the present study, using bovine serum, the fractions obtained with sodium sulfate were compared with those determined by zone electrophoresis. 1. Fibrinogen was precipitated with 4 to 10 percent of sodium sulfate. 2. ${\gamma}$-globulin required 10 to 16 percent of the salt for precipitation. 3. ${\beta}$-globulin began to precipitate at 12 percent sodium sulfate, and completed precipitation at approximately 26 percent in paper electrophoresis, while at 22 percent in agar electrophoresis. 4. ${\alpha}$-globulin completed precipitation at 13 to 28 percent sodium sulfate in paper electrophoresis and at 22 percent in agar electrophoresis. 5. Albumin began to precipitate at 14 percent of the salt, and was free from the mixture of globulins approximately at 28 percent in paper electrophoresis, while at 22 percent in agar electrophoresis. The results of comparing fractions by the two methods were as follows: 1. Euglobulin (15%) was equal to the sum of the most ${\gamma}$-globulin and a small quantity of the ${\alpha}$-, and ${\beta}$-globulins. 2. Pseudoglobulin I (15-17.5%) corresponded to the most ${\alpha}$-, ${\beta}$-globulins and a small quantity of albumin. 3. Pseudoglobulin II(18-22%) was a mixture of the ${\alpha}$-, ${\beta}$-globulins and albumin fraction. 4. Albumin (above 22%) contained the most albumin fraction separated by zone electrophoresis and a small quantity of the ${\alpha}$-, and ${\beta}$-globulins. As mentioned above the fractions obtained with sodium sulfate were a mixture of the various proportion of the fractions determined by zone electrophoresis. The solubility of serum fractions to sodium sulfate coincided with the mobility of those by zone electrophoresis. (By percent of sodium sulfate we mean gram of sodium sulfate contained in $100m{\ell}$ of solution). II. Immunological Studies on Serum Protein Fractions with Sodium Sulfate; In the previous report the fractions of bovine serum protein with sodium sulfate compared with those obtained by zone electrophoresis, and the findings were that the former contained various proportion components of the latter. In this study the author studied whether or not the fractions with sodium sulfate are simple component antigenically by immunoelectrophoresis and micro double diffusion test (Immuno-precipitation), using rabbit antiserum to bovine serum. In immunoelectrophoresis, normal bovine serum developed with rabbit antibovine serum showed about ten distinct precipitin arcs. The distribution of these arcs was as follows: 1 albumin, 2 ${\alpha}_1$-, 3 ${\alpha}_2$-, 2 ${\beta}_1$-, ${\beta}_2$-, and 1 ${\gamma}$-globulin (Fig. 7, 9). In micro double diffusion test, five to six precipitation bands could be seen between antigens and antibody, the order of the precipitation bands location is albumin, ${\alpha}$-, ${\beta}$-, and ${\gamma}$-globulin from the side of antiserum well (Fig.19). Frequently the ${\alpha}$-, and ${\beta}$-precipitation bands were separated into two or three precipitation bands, which indicated that these globuline are not a pure component antigenically as shown in immuno-electrophoresis. In both Immunological methods, the two ${\alpha}$-, ${\beta}$-precipitin arcs and bands appeared clear and strong, indicating that the two globulins reacted as strong antigens. The precipitate reaction of ${\gamma}$-globulin was shown at 12 to 16 percent sodium sulfate; ${\beta}$-globulin at 12 to 20 percent; ${\alpha}$-globulin at 12 to 22 percent (immuno-electrophoresis), at 12 to 26 percent (Diffusion); and albumin at above 22 percent. Antigenically euglobulin contained ${\gamma}$-, ${\beta}$-, and ${\alpha}$-globulins, Pseudoglobulin I and Pseudoglobulin II were composed of ${\alpha}$-, and ${\beta}$-globulins, and albumin was a mixture of ${\alpha}$-globulin and albumin determined by zone electrophoresis. The results indicated that the fractions of serum protein obtained by either method were constituents of various proteins antigenically except ${\gamma}$-globulin and albumin by Zone electrophoresis.

• Journal of the Korean Ceramic Society
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• v.29 no.4
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• pp.273-282
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• 1992

The effects of intrinsic and extrinsic gettering on the formation of microdefects in the wafer and on the electrical performance at near-surfaces of three different oxygen-bearing Czochralski silicon single crystal wafers were investigated by varying the combinations of the pre-heat treatments and the phosphorus diffusion through the back-surface of the wafers. The wafers which had less than 10.9 ppma of oxygen formed no gettering zones irrespective of any pre-heat treatments, while the wafers which had more than 14.1 ppma of oxygen and were treated by Low+High pre-heat treatments generated the gettering zone comprising oxygen precipitates, staking faults, and dislocation loops. The effects of extrinsic gettering by phosphorus diffusion were evident in all samples such that the minority carrier lifetimes were increased and junction leakage currents were decreased. However, the total gettering effects among the different pre-heat treatments did not necessarily correspond to the gettering structure revealed by synchrotron radiation section topograph.