• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.129-135
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• 2004

This study was to evaluate the effect of carbon content on metallic change and fatigue characteristics with Fe-29% Ni-17% Co, low heat expansion alloy, widely using electronic components, precision machines, and sealing with glass and metal etc. The steels were fabricated with variation of carbon content, 0, 0.03, 0.06, 0.1, and 0.20% with VIM and tensile test and fatigue test were performed to achieve the above purpose. The more carbon content, the higher hardness value and yield strength. But elongation of 0.03%C, 0.06%C, and 0.10%C specimen decreased about 2.2%, 1.5% and 0.8% respectively mote than that of the base metal. Especially the strength and elongation of 0.20%C specimen increased simultaneously about 14.4% and 7.5%. Fatigue life of 0.03%C specimen decreased but the more carbon content, the higher fatigue life over 0.06% carbon content more than that of base metal.

• Journal of Korea Society of Industrial Information Systems
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• v.2 no.2
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• pp.189-207
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• 1997

Recently, we have witnessed a host of emerging tools in the management support systems (MSS) area including the data warehouse/multidimensinal databases (MDDB), data mining, on-line analytical processing (OLAP), intelligent agents, World Wide Web(WWW) technologies, the Internet, and corporate intranets. These tools are reshaping MSS developments in organizations. This article reviews a set of emerging data management technologies in the knowledge discovery in databases(KDD) process and analyzes their implications for decision support. Furthermore, today's MSS are equipped with a plethora of AI techniques (artifical neural networks, and genetic algorithms, etc) fuzzy sets, modeling by example , geographical information system(GIS), logic modeling, and visual interactive modeling (VIM) , All these developments suggest that we are shifting the corporate decision making paradigm form information-driven decision making in the1980s to knowledge-driven decision making in the 1990s.

• Structural Engineering and Mechanics
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• v.51 no.2
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• pp.349-360
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• 2014

In this study, three approximate analytical methods have been proposed to prepare an accurate analytical solution for nonlinear oscillators with fractional potential. The basic idea of the approaches and their applications to nonlinear discontinuous equations have been completely presented and discussed. Some patterns are also presented to show the accuracy of the methods. Comparisons between Energy Balance Method (EBM), Variational Iteration Method (VIM) and Hamiltonian Approach (HA) shows that the proposed approaches are very close together and could be easily extend to conservative nonlinear vibrations.

• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.381-394
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• 2011

In this paper, a Naveir-Stokes equation is solved by using the Adomian's decomposition method (ADM), modified Adomian's decomposition method (MADM), variational iteration method (VIM), modified variational iteration method (MVIM), modified homotopy perturbation method (MHPM) and homotopy analysis method (HAM). The approximate solution of this equation is calculated in the form of series which its components are computed by applying a recursive relation. The existence and uniqueness of the solution and the convergence of the proposed methods are proved. A numerical example is studied to demonstrate the accuracy of the presented methods.

• Korean Journal of Cleft Lip And Palate
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• v.10 no.1
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• pp.1-16
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• 2007

이차구개는 발생과정에서 구개선반의 형성과 성장, 거상과 융합의 과정을 통해 형성된다. 이와 같은 이차구개의 형성과정은 미세한 분자유전학적 신호전달기전에 의해 조절되는 것으로 알려져 있어서, 신호전달과정에 관여하는 유전인자의 발현이상이 되면 정상적인 이차구개가 형성되지 못하고 구개파열이라는 선천성 기형이 발생된다. 구개파열의 유발인자들에 대한 많은 연구에도 불구하고 현재까지 정상적인 이차구개의 형성을 조절하는 분자유전학적 기전에 대해서는 명확히 알려져 있지 않다. 따라서 본 연구에서는 이차구개의 형태분화를 조절하는 분자유전학적 기전을 알아보고자, 이차구개 형성의 내적 조절인자 중 핵심유전자로 알려져 있는 Osr2가 결손된 생쥐의 이차구개 형성과정에서 정상생쥐에 비해 발현의 변동이 나타나는 유전자를 확인하였다. 유전자 발현의 변동은 발생 14.5일(E14.5)의 구개선반으로부터 추출한 total RNA를 이용하여 ACP-based GeneFishing PCR을 시행하여 확인하였고, 각각의 변동된 유전자를 동정하여 정상생쥐의 이차구개 형성과정에서의 발현양상을 in situ hybridization을 시행하여 확인하였다. 총 120쌍의 primer를 이용한 검색을 통해서 정상생쥐의 구개선반에 비해 mutant에서 발현이 변동된 유전자는 7개가 검출되었고, 이들은 모두 정상생쥐에 비해 mutant에서 발현이 증가되는 것으로 확인되었다. 검출된 유전자는 vimentin(Vim), ${\beta}$-tropomyosin 2(Tpm2), thioredoxin-like 5(Txnl5), procollagen type II alpha 1(Col2a1), Insulin-like growth factor binding protein 7(IGFbp7), Sui 1 homologs(Sui 1), Defender against cell death1(Dad1)이었다. 검출된 유전자를 동정하여 정상생쥐의 구개 형성과정에서의 발현양상을 알아본 결과, Col2a1 을 제외한 유전자들은 모두 E13.5의 구개선반에서 특이적으로 발현되고 있었으나 구개선반이 융합된 E15.5에서는 Vim, Txnl5 그리고 Dad1 만이 봉합선을 따라 발현이 지속되고 있었다. 이상의 결과로 보아 검출된 유전자들은 구개선반의 형태분화과정에서 발현되어 이차구개의 형성과정에 관여할 것으로 여겨진다. 또한 이들은 이차구개 형성의 내적조절인자인 Osr2의 downstream target 으로 구개선반의 성장과 융합과정에 직접적으로 관여하는 유전물질일 것으로 추정된다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.310-313
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• 2009

Several high nitrogen stainless steel ingots(100kg) were fabricated with changing Ni and $[N]_2$ contents by Pressurized Vacuum Induction Melting(P_VIM). After free forging process, chemical compositions, microstructure and mechanical properties were estimated. Hardness was increased with the increase of $[N]_2$ content. Furthermore, microstructure including a lot of tempering twins was observed with optical microscope. Mechanical properties were estimated as function of solution treatment temperature and cooling method(air/water) under duration time of 1 hr on sample that were fabricated with Ni content under the atmospheric $[N]_2$ pressure. At solution treatment range of $1050{\sim}1100^{\circ}C$, hardness was decreased with the increase of solution temperature and there were little discrepancy of microstructure and hardness with cooling method. Computer simulation was carried out in order to inspect pass schedule in cold rolling process. When the condition of simulation was roll speed of 2.5mpm, rolling rate $15{\sim}17%$ per pass, it was ascertained that the formation such as deformation by sticking and lamellar sliver etc. was restricted from a simulation.

• Structural Engineering and Mechanics
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• v.37 no.4
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• pp.415-425
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• 2011

In this study, the homotopy perturbation method (HPM) is applied to free vibration analysis of beam on elastic foundation. This numerical method is applied on three different axially loaded cases, namely: 1) one end fixed, the other end simply supported; 2) both ends fixed and 3) both ends simply supported cases. Analytical solutions and frequency factors are evaluated for different ratios of axial load N acting on the beam to Euler buckling load, $N_r$. The application of HPM for the particular problem in this study gives results which are in excellent agreement with both analytical solutions and the variational iteration method (VIM) solutions for all the cases considered in this study and the differential transform method (DTM) results available in the literature for the fixed-pinned case.

• Journal of applied mathematics & informatics
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• v.31 no.1_2
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• pp.165-177
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• 2013

In this paper, we apply Homotopy perturbation transform method (HPTM) for solving singular fourth order parabolic partial differential equations with variable coefficients. This method is the combination of the Laplace transform method and Homotopy perturbation method. The nonlinear terms can be easily handled by the use of He's polynomials. The aim of using the Laplace transform is to overcome the deficiency that is mainly caused by unsatisfied conditions in other semi-analytical methods such as Homotopy perturbation method (HPM), Variational iteration method (VIM) and Adomain Decomposition method (ADM). The proposed scheme finds the solutions without any discretization or restrictive assumptions and avoids the round-off errors. The comparison shows a precise agreement between the results and introduces this method as an applicable one which it needs fewer computations and is much easier and more convenient than others, so it can be widely used in engineering too.

• Korean Journal of Microbiology
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• v.44 no.4
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• pp.339-345
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• 2008

This study was to detect MBL (metallo-${\beta}$-lactamase) among glucose non-fermenting Gram-negative bacilli isolated from clinical specimen and to search antimicrobial combination therapy against MBL producing Pseudomonas aeruginosa. Among fifty one isolates of Gram-negative bacilli with reduced imipenem susceptibility ($MIC{\ge}8{\mu}g/ml$), nine isolates have shown positive results in MBL detection test. They were seven Achromobacter xylosoxidans subsp. xylosoxidans and two P. aeruginosa. The results from EDTA-DDST coin-cided with those of PCR and nucleotide sequence analysis which showed the presence of $bla_{VIM-2}$. The combination of aztreonam (AZT) and piperacillin-tazobactarn (TZP) or AZT and amikacin (AN) screened by one disk synergy test showed no synergistic effect. Triple antibiotic combination therapy with AZT, TZP and AN, however, was shown to be effective and the most synergistic after 8 hrs of exposure. This result strongly suggest that the triple combination therapy of AZT, TZP, and AN could be useful for the treatment of infection caused by MBL producing Gram-negative bacilli.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.4
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• pp.428-435
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• 2019

The rapid increase and dissemination of carbapene mases, such as Klebsiella pneumoniae carbapenemase (KPC), has become a major problem within the field of healthcare-related infection. There are few antibiotics to treat carbapenem-resistant Enterobacteriaceae (CRE) infections, so the identification of resistant bacterial mechanisms is critical to initiate infection control and conduct epidemiological research. A rapid and effective method for detecting KPC-producing bacteria is needed to avoid therapeutic failures and introduce measures to prevent and control the dissemination of these multi-resistant bacteria. During the study period, 31 isolates (seven isolates of Acinetobacter spp., six isolates of Morganella morganii, five isolates of Pseudomonas aeruginosa, five isolates of Proteus mirabilis, one isolate of Proteus vulgaris, two isolates of Enterobacter cloacae, one isolate of Enterobacter aerogenes, one isolate of Klebsiella pneumoniae, one isolate of Klebsiella oxytoca, one isolate of Serratia marcescens and one isolate of Escherichia coli) were identified by the VITEK. Gram negative rod bacteria were the most frequently isolated from urine (35.5%), blood (19.4%), sputum (16.1%), pus (9.7%), ascitic fluid (9.7%), tracheal aspirates (6.5%) and bile juice (3.2%). Analysis using the PCR method identified the bla_KPC gene in the K. oxytoca1 strain, but the bla_IMP, bla_VIM and bla_OXA-48 genes are not amplified. In conclusion, diagnosis using the PCR method can accurately and quickly diagnose KPC, thus establishing quick preventive measures to prevent the spread of KPC in hospitals.