• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.9
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• pp.961-971
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• 2008

In the design of a rotor shaft, care should be taken to minimize vibration by taking into account the sources of vibration. In addition, the intensity critical speed, stability, and other related aspects of the system must be considered. especially when it is operated at a critical speed, it is important to address issues related to vibration, as an increase in the whirling response of the rotor shaft can cause damage to the shaft, destruction of the rotor parts, and detrimental abrasions on the bearings. In this thesis, the vibration characteristics of a rotor shaft are investigated through the use of the finite element method. Variations of the diameters and lengths were used to determine the effect of a rotor shaft using Beam No.188(3D linear strain beam) in ANSYS version 11.0 as a universal interpretation program for finite elements. Special care was taken to prevent excessive vibration, which can result from resonance at the initial stage, in the formulation of a dynamic design for a rotor shaft through calculations while changing the diameters and the lengths of the shaft. Moreover, the dynamic characteristics of the critical speed, total mass, D/L(diameter to length) ratio, and natural frequency were verified. Furthermore, the rotor shaft applied by bearing element was calculated and compared by using Combi No. 214(2-D spring-damper bearing).

• Geomechanics and Engineering
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• v.12 no.1
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• pp.161-183
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• 2017

This paper investigates the damage identification of the concrete pile element through axial wave propagation technique using computational and experimental studies. Now-a-days, concrete pile foundations are often common in all engineering structures and their safety is significant for preventing the failure. Damage detection and estimation in a sub-structure is challenging as the visual picture of the sub-structure and its condition is not well known and the state of the structure or foundation can be inferred only through its static and dynamic response. The concept of wave propagation involves dynamic impedance and whenever a wave encounters a changing impedance (due to loss of stiffness), a reflecting wave is generated with the total strain energy forked as reflected as well as refracted portions. Among many frequency domain methods, the Spectral Finite Element method (SFEM) has been found suitable for analysis of wave propagation in real engineering structures as the formulation is based on dynamic equilibrium under harmonic steady state excitation. The feasibility of the axial wave propagation technique is studied through numerical simulations using Elementary rod theory and higher order Love rod theory under SFEM and ABAQUS dynamic explicit analysis with experimental validation exercise. Towards simulating the damage scenario in a pile element, dis-continuity (impedance mismatch) is induced by varying its cross-sectional area along its length. Both experimental and computational investigations are performed under pulse-echo and pitch-catch configuration methods. Analytical and experimental results are in good agreement.

• Journal of Plant Biotechnology
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• v.38 no.4
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• pp.308-314
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• 2011

Efficient transformation and regeneration methods are a priority for successful application of genetic engineering to vegetative propagated plants such as grape. In this study, methods for Agrobacterium tumefaciens-mediated transformation and plant regeneration of grapevine (Vitis vinifera) were evaluated. Tamnara, Heukgoosul, Heukbosek, Rizamat were co-cultivated with Agrobacterium strains, LBA4404 containing the vector pBI121 carrying with CaMV 35S promoter, GUS gene as reporter gene and resistance to kanamycin as selective agent. Seven percent of the maximum regeneration frequency was obtained from co-cultivated with explants from Rizamat with LBA4404 strain on selection medium with kanamycin. The addition of acetosyringone, 200 ${\mu}m$ in virulence induction step was a key factor for successful GUS reporter gene expression in grapevine transformation. Transgenic plants showed resistance to kanamycin and the GUS positive response in leaf ($T_0$) stem ($T_0$) and petiole ($T_0$).

• Journal of Preventive Medicine and Public Health
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• v.38 no.2
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• pp.182-188
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• 2005

Objectives: This study was undertaken to investigate the source of infection and mode of transmission of shigellosis, which occurred sporadically among residents and students in a subcounty of Cheongwon county, Chungbuk province, Korea, from June 4 to July 3 2003. Methods: 692 subjects completed a questionnaire and provided a swab for microbiological examinations,and 7 environmental specimens were examined for bacterial organisms. PFGE (pulsed-field gel electrophoresis) and fingerprinting were performed to find the genetic relationship among the temporally associated sporadic isolates. Results: A total of 29 patients had symptoms consistent with the case definition, with 13 confirmed and 16 suspected cases. The frequency of diarrhea was 6 times or more a day (80.8%), with a duration of 1 to 4 days (88.5%) in most cases. The most common symptoms accompanying the diarrhea were fever (80.9%) followed by abdominal pain (76.9%), headache (65.4%), chill (61.5%), vomiting (46.2%) and tenesmus (15.4%). The epidemic curve was characteristic of a person-to-person transmission. The PFGE and fingerprinting demonstrated identical or similar DNA patterns among the 3 Shigella sonnei isolates (A51, A53 and A61 types) found in this outbreak. Conclusion: A genetically identical strain of S. sonnei was estimated to be the cause of this outbreak, and the mode of transmission was most likely person-to-person.

• The Journal of the Korean Society for Microbiology
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• v.18 no.1
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• pp.53-58
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• 1983

Enterotoxigenic E. coli is one of causative agents of the infantile diarrhea and traveler's diarrhea. A modified infant mouse assay(IMA) was developed for the detection of heat stable enterotoxin (ST) of E. coli isolated from diarrheal and control infants and assay system was established with using enterotoxin producing reference strains. The supernatant of the 24 hour-shaking culture of E. coli in Casamino Acid Yeast Extract Salt Broth(CYES-2) was ingested orally into the 2-4 day old ICR mice. After the mice were kept at $25^{\circ}C$ for 4 hours, they were sacrificed and the gut weight body weight ratio(GW/BW) was taken as the index of fluid accumulation induced by heat stable enterotoxin of E. coli. The results obtained were as follows; 1. The GW/BW responses of IMA tested with enterotoxin reference strains of E. coli(E. coli O148H28:$ST^+LT^+$, E. coli $O78H^-:ST^+LT^+$, E. coli O15H11:$ST^-LT^+$, E. coli O1H7:$ST^-LT^-$) appeared ta be ST dose-dependent, and not LT-dependent. From the dose-response curve, $25{\mu}l$ of culture supernatant was determined as test amount of the IMA. 2. Frequency distribution of IMA result from 643 strain of E. coli showed normal distribution at low GW/BW ratio and dispersed pattern at high GW/BW ratio. The GW/BW ratios of $0.056{\pm}0.004(mean{\pm}SD)$ of normal distribution which distributed from 0.044 to 0.068(P<0.01) was considered as ST negative. Thus the GW/BW ratio above 0.069 could be regarded as ST positive.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.167-174
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• 2022

The objective of this study is to evaluate the dynamic properties of DUS (damping-up system) composed of the materials with excellent damping capacity, and to compare with those of the conventional hangar bolt. The main parameters are the type and hardness (𝜂_H), of rubber and the prestress force (value converted from the compression strain (𝜂_R) in the stress-strain relationship of rubber). The dynamic properties were examined from the natural frequency (𝜔_n), maximum response acceleration (A_m), amplification coefficient (𝛼_p), maximum relative displacement (𝚫_m), and damping ratio (𝜉_D). The test results showed that the A_m, 𝛼_p, and 𝚫_m values of DUS were 46.3%, 46.6% and 62.9% lower, respectively, and the 𝜉_D value was 3.89 times higher, when compared to those of the conventional hangar bolt. In particular, the 𝛼_p value was 1.3 for DUS, and 2.45 for the conventional hanger bolt, which were similar to those of rigid and flexible components specified in KDS 41 17 00, respectively. Consequently, in the optimal details of DUS, the 𝜂_H values of 50 and 45 were required for the NR (natural rubber) and EPDM (ethylene propylene diene monomer), and the 𝜂_R value of 5% was also recommended.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.1
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• pp.85-92
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• 2015

This article presents the dynamic instability response of sigmoid functionally graded material plates on elastic foundation using the higher-order shear deformation theory. The higher-order shear deformation theory has ability to capture the quadratic variation of shear strain and consequently shear stress through the plate thickness. The governing equations are then written in the form of Mathieu-Hill equations and then Bolotin's method is employed to determine the instability regions. The boundaries of the instability regions are represented in the dynamic load and excitation frequency plane. The results of dynamic instability analysis of sigmoid functionally graded material plate are presented using the Navier's procedure to illustrate the effect of elastic foundation parameter on dynamic response. The relations between Winkler and Pasternak elastic foundation parameter are discussed by numerical results. Also, the effects of static load factor, power-law index and side-to-thickness ratio on dynamic instability analysis are investigated and discussed. In order to validate the present solutions, the reference solutions are used and discussed. The theoretical development as well as numerical solutions presented herein should serve as reference for the dynamic instability study of S-FGM plates.

• Journal of dental hygiene science
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• v.9 no.3
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• pp.361-367
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• 2009

This study was conducted to know oral maxillofacial symptoms accroding to dental fear and dental use behavior. 334 persons Older than junior high school students in Daegu, South Korea who visited to dental clinic were targeted From March 1.2008 to March 15, 2008. Statistics tool was SPSS 12.0 for Windows. General characteristics and response degree according to oral maxillofacial symptoms was analyzed by frequency study. Fear and difference according to oral maxillofacial symptoms we re conducted by T-test and One-Way ANOVA. Correlation analysis was used to verify relation between fear and oral maxillofacial symptoms. Results are followings. 1. Women felt fear higher than men did. Persons who were older felt fear higher and these were statistically related. 2. Extraoral external was 62.9%, hightest on the symptoms response degree according to oral maxillofacial symptoms. Feeling back side of the head on the strain and neck was stiff on the items were high. 3. Oral maxillofacial symptoms were high in the case when they had regular inspection, experience of scaling, experience of anesthesia and visited to the clinic often. And. Two cases(having regular inspection and visiting to the clinic often) were statistically related. Conclusion: Each pan of oral maxillofacial symptoms in the high fear group according to oral maxillofacial symptoms and it was all statistically related. And, fear and each oral maxillofacial pains were positively related and it was statistically related.

• The Journal of Korean Medicine
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• v.19 no.1
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• pp.234-250
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• 1998

Bujeonghangamtang(扶正抗癌湯) has been used for cure of tumor as a traditional medicine without any experimental evidence to support the rational basis for its clinical use. This study was carroed out to evaluate the possible therapeutic or antitumoral effects of Bujeonghangamtang extract against tumor, and to carry out some mechanisms responsible for its effect. Some kinds of tumor were induced by .the typical application of 3-methylcholanthrene (MCA) or by the implantation(s.c) of malignant tumor cells such as leukemia cells(3LL cells) or sarcoma cells(Sl80 cells). Treatment of the Bujeonghangamtang water-extract (dailly 1mg/mouse, i. p.) was continued for 7 days prior to tumor induction and after that the treatment was lasted for 20 days. Against squamous cell carcinoma induced by MCA, Bujeonghangamtang decreased not only the frequency of tumor production but also the number and the weight of tumors per tumor bearing mice (TBM). Bujeongmngamtang also significantly suppressed the development of 3LL cell and S180 cell-implanted tumors in occurence-frequency and their size, and some developed tumors were regressed by the continuous treatment of Bujeonghangamtang extract into TBM. In vitro, treatment of Bujeonghangamtang extract had no effect on the growth of some kinds of cell line such as FsaII, A431 strain but significantly inhibited the proliferation of 3LL, S180 cells and augmented the DNA synthesis of mitogen-activated lymphocytes. Bujeonghangamtang also stimulated the migrative ability of leukocyte, the MIF and IL-2 production of T lymphocytes, but not IL 6 production of B cells. Bujeonghangamtang-administration to mice enhanced NK cells attivities. These results demonstrated that Bujeonghangamtang extract exhibited a significant prophylactic benefits against tumors and its antitumor activity was manifested depending on the type of tumor cells. And these results also suggested that effect of Bujeonghangamtang might be chiefly due to nonspecific enhancement of NK cell activities and cell-mediated immune responses.

• Journal of Biomedical Engineering Research
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• v.18 no.3
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• pp.273-283
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• 1997

Electrogastrography(EGG), the cutaneous recording of the myoelectrical activity of the stomach using surface electrodes, is attactive due to its non-invasiveness. Despite many attempts made over the decades, analysis of surface EGG has not led to identification of contraction-related electrical response activity of the stomach that would help the clinician to diagnose motility disorders of the stomach. We propose feasible methods to detect the gastric contraction by spectrum analysis and vector analysis of the surface EGG signal. A running spectral analysis(RSA) based on the fast Fourier transform (FFT) was applied to the filtered EGG signal. The powers of dominant frequency and its harmonics were compared with gastric contraction signals such as the strain gauge signal from the gastric serosa in dog or the antropyloric pressure in human. And we also carried out vector analysis of the filtered EGG signals obtained from three paired electrodes. The amplitude and direction of the calculated EGG vector were analyzed and compared with the gastric contraction signals. From the spectrum analysis, we found that the increase of the power of the first harmonic of the dominant frequency was highly correlated with the gastric contraction. And from the vector analysis of the EGG signal, we found a typical change of the amplitude and direction of the EGG vector, which can indicate occurrences of the gastric contraction.