• Journal of Ecology and Environment
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• v.31 no.4
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• pp.255-260
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• 2008

A commonly held view in studies of character displacement is that character states of both species are shifted in areas of sympatry. This view has been confirmed in an overwhelming number of cases for ecological character displacement. Excluding species pairs in which one of the two interacting species is found only within the distribution of the other species and species displaying gynogenesis, the pattern of reproductive character displacement is asymmetrical in that the shift in character states between areas of symaptry and allopatry occurs in only one of the two interacting species. Hypotheses for the reasons behind this asymmetry in reproductive character displacement include (1) homogenization by gene flow, (2) other mechanisms of reproductive isolation, and (3) sufficient reproductive isolation being provided by one of the interacting species exhibiting a pattern of reproductive character displacement. Because reproductive isolation can be achieved by divergence at any point in a sequence of premating reproductive behaviors and postmating developments, it is necessary to understand the mechanisms of reproductive isolation of two interacting taxa in areas of sympatry and allopatry and to analyze the relative contributions of potential factors to reproductive isolation to disentangle hypotheses for the patterns of asymmetry.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.227-232
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• 2003

As the most precision equipment requiring very strict vibration environment are vulnerable to the surrounding vibration condition, they adapt the passive or active vibration isolation system. When it comes to the passive isolation system, the resonance of the isolation system causes excessive resonance response, and finally results in the degrade the equipment performance. This paper deals with the active control method to control this resonance induced response, and includes the experiment on the active control for controlling the resonance response on the table against the excitation of the same frequency with the natural frequency of the isolation system. The electromagnetic actuator was designed and the control effect was verified by the experiment. The experiment showed that the electromagnetic actuator is effective for controlling the low frequency isolation resonance response of the precision equipment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.59-64
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• 2001

Recently, among those general contractors and construction material production companies in korea, this concept is lively obtained to reduce the floor impact sound. This attempt is continuously tried for developing the floor impact isolation material. However the assesment of the isolation performance is often ignored and even there seems no differences in comparison with the general the isolation performance of the floor impact. This is often occurred for their only respect with the material of the floor impact isolation performance. Therefore, this study analysed the expected problems for site application of currently applied the isolation material and its capacity which as the floor impact reducing material, and presented several major assesment items and checklist which should be inspected in advance of their development or site application.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.497-504
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• 2005

This paper presents the results of experimental studies on the equipment isolation effect considering the floor response. For this purpose, shaking table tests were performed. For the measuring the floor response, numerical analysis was performed. For the isolation for the equipment, Natural Rubber Bearing(NRB), High Damping Rubber Bearing(HDRB) and Friction Pendulum System(FPS) were used. Finally, it is presented that the isolation systems used in this test can be adopted for the small equipment isolation. But the rubber bearing used in this study affected to the temperature change very sensitively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.3 s.108
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• pp.307-312
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• 2006

In this study a vibration isolation system with the cradle-type support was designed so as to reduce the transient vibration due to positioning motion of the moving mass on worktable as well as to achieve the desired isolation efficiency on the floor vibration. The design procedure was performed in the two steps. The first step to select appropriate isolators to meet the isolation efficiency, and the second step is to reduce the transient vibration of the worktable by adopting the cradle-type support. After the application of the selected isolators with the cradle-type support to the system it was shown that the required vibration criterion(VC-D) was easily satisfied and that the undesirable transient vibration was reduced remarkably.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.6
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• pp.810-818
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• 2011

This paper analyzed the suitability about the isolation performance criteria which was based on human impedance and effect of current in IEC 60479-1 on the safety of human being was examined. The method of evaluation by megger and DC voltmeter was analyzed. The differences of isolation performance according to design of high-voltage system were analyzed. The factors which affect the insulation performance were analyzed for HFCV, EV, HEV, etc. through analysis of the isolation performance evaluation method. Finally, design for improved isolation performance was proposed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.236-243
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• 1999

A comparative study on aseismatic performances of various base isolation systems for the multi-span continuous bridge is carried out. Several leading base isolation systems the LRB system the RF system the R-FBI system and the EDF system are considered, The displacement of the deck the deformation of the upper ends of the piers the shear force and the bending moment of the lower ends of the piers are obtained by using the accelerograms of the N00W component of El Centro earthquake(1940) and the N90W component of Mexico City earthquake(1985) Nonlinear time-history analysis is carried out. comparisons of the results with the conventional bearing show that the base isolation systems are very effective in reducing the forces transmitted to the superstructures. Furthermore the results also show that the friction-type base isolation systems are less sensitive to unexpected variations in frequency content of the ground acceleration. The R-FBI system shows a good aseismatic performance comparing with other base isolation systems.

• Structural Engineering and Mechanics
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• v.51 no.4
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• pp.643-650
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• 2014

A chaotic vibration isolation system is designed according to the chaotic vibration theory in this paper. The strong nonlinearity is generated by the system. Line spectra in the radiated noise maybe easily detected caused by marine vessels. It is Important to reduce the line spectra by improving the acoustic stealth of marine vessels. A multi-degree-freedom (MDF) nonlinear vibration isolation system (NVIS) system is setup by the experiment and finite element method. The model is established with finite element method. The results show that the behavior of the device gradually varies from period bifurcation into chaotic state and the line spectrum is changed from single spectral structure into broadband spectral structure. It is concluded that chaotic vibration isolation is preferable contrasted on line spectra isolation.

• Clinical and Experimental Reproductive Medicine
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• v.10 no.1
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• pp.25-37
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• 1983

A group of 180 men who visited Urology Department of Severance hospital, including 115 patients with nongonococcal urethritis (N.G.U.), 27 patients with prostatitis, 13 patients with gonococcal urethritis (G.U.) and 25 healthy medical student controls were investigated for the isolation of Ureaplasma urealyticum (T-strain mycoplasma) from the specimen of ureaplasma discharge, urine and semen. Taylor-Robinson media of T-broth and T-agar was used for the isolation of Ureaplasma urealyticum. To the best of our knowledge, the study on the culture of Ureaplasma urealy ticum was reported for the first time in Korea. The followis g results were obtained: 1. The isolation rate of Ureaplasma urealyticum in nongonococcal urethritis (53.0%) revealed highest of those in the other three groups of prostatitis, gonococcal urethritis and control (40.7%,38.4% and 16.0% respectively). 2. As for the specimens, urethral discharge revelaed higher isolation rate of Ureaplasma urealyticum (54.6%) than first voided urine (50.0%). 3. The more consorts patients had, the higher positive culture rate of Ureaplasma urealyticum were revealed. The isolation rate in case of more than one causal in nongonococcal urethritis (27.8%) revealed much higher than in case of marital only (5.2%), one regular (6.1%) and one causal 03.9%). 4. 2.6% of isolation rate of Ureaplasma urealyticum revealed in patients with nongonococcal urethritis who visited the clinic in later than 4 weeks after the symptoms developed. However, the isolation rate in patients who visited within 4 weeks revealed 50.3%. The lower isolation rate of Ureaplasma in the late treatment seekers might be probably due to the suppression effect against Ureaplama urealyticum from the possible previous self antibiotic treatment. 5. Attachment of Ureaplasma urealyticum mostly to the neck and head portion of the spermatozoa seemed to playa role to affect the motility of sperms.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.1
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• pp.27-36
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• 2013

In this study, seismic isolation technology to the lighthouse structure is suggested and isolation effects on response reduction are studied for three types of isolation models with the proposed seismic isolation technology. A seismic isolation system is installed on the base of the lighthouse structure in model 1, on the base of the lighthouse lens in model 2, and on the base of both of them in model 3. The dynamic time history analysis verifies that in case of model 1, the earthquake loading is greatly reduced and the accelerations of superstructure are greatly reduced. Also, the inter-story drifts are very small and can be neglected. The isolated model is in translational state and can be seen as a rigid whole. as a results, model 1 is very effective to mitigate the influence of earthquake on structures. In model 2, isolation effects are valid but special care should be taken to failure of the non-isolated lighthouse sub-structure. In model 3, isolation effects are also valid but the effects are small. model 3 is less effective than model 1.