• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.19-25
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• 2001

Unlike structures in the air, the vibration analysis of a submerged or floating structure such as offshore structures or ships is possible only when the fluid-structure interaction is understood, as the whole or part of the structure is in contact with water. This paper introduces two methods to find natural frequency in consideration of fluid-structure interaction, direct coupled vibration analysis and fluid-structure modal coupled vibration analysis. The purpose of this study is to analyze the vibration characteristic of a submerged vehicle to obtain the anti-vibration design data, which could be used in the preliminary design stage. The underwater pressure hull of submerged vehicle is used as the model of this study. The F.E.M. model is meshed by shell and beam elements. Also, considering the inner hull weight, the mass element is distributed in the direction of hull length. Numerical calculations are accomplished by using the commercial B.E.M. code. The characteristics of natural frequency, mode shape and frequency-displacement response are analyzed.

• BMB Reports
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• v.37 no.2
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• pp.167-176
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• 2004

Although efficient antiviral lamivudine is used for HBV-infected patients, a prolonged treatment with nucleoside analogs often results in lamivudine-resistant variants. In this study, we evaluated the fidelity of the lamivudine-resistant variants. The FLAG-tagged wild-type (FPolE) and Met550 variants (FPolE/M550A, M550V, and M550I) of HBV DNA polymerases were expressed in insect cells then purified. Like many other reverse transcriptases, no $3'{\rightarrow}5'$ exonuclease activity was detected in the HBV DNA polymerase. Since there is no proofreading activity, then the use of the site-specific nucleotide misincorporation method is beneficial. From the $f_{ins}$ value analysis, it is evident that M550I and M550V exhibit higher fidelity values than the wild-type HBV DNA polymerase, while M550A exhibits similar fidelity values. It is therefore suggested that lamivudine resistance comes from the stringency to dNTP binding and the discrimination of dCTP and lamivudine in M550V and M550I.

• International Journal of Clinical Preventive Dentistry
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• v.14 no.4
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• pp.264-270
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• 2018

Objective: This study performed a quantitative analysis using the real-time polymerase chain reaction technique to examine the oral microbial prevalence in adults and intended to examine the correlations between risk factors of periodontal disease and oral bacteria and correlation between oral test scores and oral microorganisms. Methods: We examined papillary marginal attached (PMA) index, modified patient hygiene performance (M-PHP) index, probing depth (PD), modified gingival index, and oral bacteria counts and surveyed 117, 20 years or older adult males and females who visited dental clinics in the Daejeon region to analyze the prevalence and oral health. Results: The prevalence was 100% for Fusobacterium nucleatum, meaning it was observed in all examined subject, 85.5% for Parvimonas micra, 76.1% for Prevotella intermedia, and 72.6% for Tannerella forsythia. The averages of P. gingivalis and T. forsythia increased as the examined subjects were older, and there was a statistically significant difference between T. forsythia and E. nodatum in relation to medical history, between P. intermedia and P. micra in relation to gender, and between P. intermedia and E. corrodens in relation to smoking (p<0.05). For a correlation between the oral test scores and oral microorganisms, P. gingivalis and F. nucleatum was highly correlated with PD (correlation coefficient of 0.51 and 0.41) (p<0.01) while P. gingivalis, P. micra, C. rectus, and E. nodatum were significantly correlated with M-PHP index, gingival index, PD, and PMA index (p<0.01, p<0.05). Conclusion: For oral health management of adults, the age, systemic disease, and smoking are closely related to oral bacteria, and P. gingivalis, T. forsythia, F. nucleatum, P. intermedia, P. micra, C. rectus, E. corrodens, and E. nodatum are considered to be the oral microorganisms that indicate periodontal health.

• Carbon letters
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• v.12 no.4
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• pp.236-242
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• 2011

The oxyfluorination effects of activated carbon nanofibers (OFACFs) were investigated for $CO_2$ storage. Electrospun CFs were prepared from a polyacrylonitrile/N,N-dimethylformamide solution via electrospinning and heat treatment. The electrospun CFs were chemically activated in order to generate the pore structure, and then oxyfluorination was used to modify the surface. The samples were labeled CF (electrospun CF), ACF (activated CF), OFACF-1 ($O_2:F_2$ = 7:3), OFACF-2 ($O_2:F_2$ = 5:5) and OFACF-3 ($O_2:F_2$ = 3:7). The functional group of OFACFs was investigated using X-ray photoelectron spectroscopy analysis. The C-F bonds formed on surface of ACFs. The intensities of the C-O peaks increased after oxyfluorination and increased the oxygen content in the reaction gas. The specific surface area, pore volume and pore size of OFACFs were calculated by the Brunauer-Emmett-Teller and density functional theory equation. Through the $N_2$ adsorption isotherm, the specific surface area and pore volume slightly decreased as a result of oxyfluorination treatment. Nevertheless, the $CO_2$ adsorption efficiency of oxyfluorinated ACF improved around 16 wt% due to the semi-ionic interaction effect of surface modificated oxygen functional groups and $CO_2$ molecules.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.185-192
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• 2002

The performance of old and the new concrete construction depends upon bond strength between old and the new concrete. Current adhesive and strength measurement method ignores the effect of stress concentration from shape of specimens. Therefore, this research calculates stress concentration coefficient as the ratio of drilling depth to drilling diameter($h_s/D$), the ratio of overlay thickness to drilling diameter($h_0/D$), the ratio of steel disk thickness to drilling diameter(t/D), the ratio of overlay elastic modulus to substrate modulus($E_1/E_0$), the distance from core to corner border(L_$_{corner}$) and the distance between cores(L_$_{coic}$) vary. The finite element method is adapted to analysis The results from 'the F.E.M analysis are as follows. The stress concentration effects can be minimized when the ratio of drilling depth to drilling diameter($h_s/D$) is 0.20~0.25, the elastic modulus ratio($E_1/E_0$) is 06~1.0, and the ratio of steel disk thickness to drilling diameter(t/D) is 3.0. The overlay thickness, the distance from specimens to corner border(L_$_{corner}$), the distance between cores(L_$_{coic}$) almost do not affect to the stress concentration.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1590-1594
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• 2007

This paper describes a case study on dynamic characteristics analysis of a 5-axis multi-tasking machine tool of ram-head typed. Natural frequency and corresponding vibration modes of the machine tool structure were obtained by using both FEM modal analysis and an experimental modal test(impulse hammer test). Both the theoretical and experiment analysis results showed good agreement with each other. Finally, some discussion and review, from the view point of resonance vibration and/or mode coupled chatter, were made based on the analysis results.

• Journal of Power System Engineering
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• v.15 no.2
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• pp.31-36
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• 2011

The flow characteristics on the periodically arranged semi-circular ribs in a rectangular channel for turbulent flow have been investigated numerically. The aspect ratio of the rectangular channel was AR=5, the rib height to hydraulic diameter ratio was 0.07 and rib height to channel height ratio was e/H=0.117. The v2-f turbulence model and SST k-${\omega}$ turbulence model were used to find the flow characteristics of near the wall which are suited for realistic phenomena. The numerical analysis results show turbulent flow characteristics and pressure drop at the near the wall as observed experimentally. The results predict that turbulent kinetic energy(k) is closely relative to the diffusion of recirculation flow, and v2-f turbulence model simulation results have a good agreement with experimental.

• Bulletin of the Korean Chemical Society
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• v.17 no.2
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• pp.162-167
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• 1996

Two redox processes of methyl viologen (+2/+, +/0) in acetonitrile were investigated by using channel electrode voltammetric and in situ electrochemical ESR methods. Two separated unequal plateau currents of the first (+2/+) and second (+/0) redox processes of the viologen were observed in the channel electrode voltammograms and showed a cube-root depedndence on the electrolyte flow rate, respectively. The simple Levich analysis resulted in two different diffusion coefficients of $D_{+2}=2.2{\times}10^{-5}\;cm^2/s$ and $D_+=3.0{\times}10^{-5}cm^2/s$ from the limiting currents. In situ electrochemical ESR studies were performed for the monocation radicals generated at the potentials of the two plateau currents in the electrolyte flow range $1.3{\times}10^{-1}{\geq}v_f{\geq}2.7{\times}10^{-3}\;cm^3/s$. Backward implicitfinite difference method was employed to simulate the electrochemical kinetic problem of two sequential electron transfers ($MV^{+2}+e{\leftrightarrows}MV^+,\;MV^{+}+e{\leftrightarrows}MV^0$) coupled with reversible comproportionation ($MV^{2+}+MV^0{{\leftrightarrows}^{k_f}_{k_b}}2MV^+$). $k_f$ was found to be greater than ($10^6M^{-1}s^{-1}.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.6
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• pp.323-330
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• 1988

The spatial distribution of sea water temperature variation pattern in the South-eastern coastal region of Korea was studied by empirical orthogonal function (E. O. F) analysis in several depths from surface to 300m using the monthly mean water temperature averaged for 23 years, water mass analysis by T. S diagram and sectional diagram of water temperature. Typical type of water temperature variation in this area can be divided into surface (0m-50m), subsurface (100m-150m) and intermediate (200m-300m) layer. The first mode value of water temperature change on the surface layer showed $99\%$ of total variation, and decreased with the increase of the depth. It is deduced to be in the range of $60-70\%$ on the 300m layer. The representative type of water temperature fluctuation by the first mode in each layer is as follows. Water temperature change in the surface layer showed a seasonal variation. In the subsurface layer, it is governed by the interaction of the Tsushima Warm Current water with the cold water and by the heat transfer process from the upper layer. In the intermediate layer, water temperature variation seems to be governed by the advection of the bottom cold water.

• Journal of agricultural medicine and community health
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• v.7 no.1
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• pp.74-79
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• 1982

Recently in Korea, integration of F.P. & MCH programs for effective and efficient implementation of the health programs has been discussed actively. In fact, categorical health workers in fields have been trained and changed as an integrated health workers by government. But one of the most important problems that had to be solved for successful integration of F.P. and MCH programs, is that there must be a common indicator for the evaluation of the two health services (integrated indicator). We regarded reproductive efficiency (=R.E.) that had been proposed by Charlotter M$\ddot{u}$ller et al, as the good integrated indicator. The object of this brief article is to introduce the meaning of reproductive efficiency and to illustrate the usefulnesses of R.E. as the integrated health indicator by applying this indicator to the data from preliminary survey of Seosan demonstration project for integration of F.P. & MCH service supported by WHO. The results and conclusions are as follows 1) Definition of R.E. is the percentage of pregnancies that succeed in production normal, surving children after taking into account the frequency of all measurable types of adverse outcomes (End point for evaluation of survival is one year of age). 2) On the basis of the past pregnant history, reproductive efficiency of the 2,484 eligible women (15-44 years) was roughly 75% (But, in the concept of good births, it is not regarded whether the survived infant is normal health or not). 3) Compared with the results of the other two surveys of the rural area in Korea, reproductive efficiency has been slightly decreased than before, in spite of family planning and MCH services for past 20 years. Because the quantity of increased abortion rate overwhelmed that of the decreased infant mortality rate. 4) Reproductive efficiency has the object for measure many events during the period from the conception (Wanted pregnancy) to an normal surviving children as an 1 year of age. So these heterogenous adversities, ie, induced abortion, still births, spontaneous abortion, neonate & infant death, are aggregated as R.E. However, if the information of these important events and reproductive efficiency were given, R.E. is used as the comprehensive evaluation indicator for F.P. and M.C.H. after meticulous analysis the various components of R.E. 5) Economic loss for adverse outcomes of preg were pregnancy were calculated applying the medical cost at the relatively small sized hospital of small city. Economic loss for 100 cases of adverse outcome is 10,420,000 won, and economic loss for infant death is 46.1% of the total loss. So, it is rational to invest much more effort and than before to MCH programs.