Expression of E . coli cdd Gene and Plasmid Stabilty in Yast

Woochang Shin,Sangyong Lee,Taeho Kim,Sunghee Park,Soonduck Hong 한국미생물생명공학회(구 한국산업미생물학회) 1992 한국미생물생명공학회 학술발표초록집 Vol.1992 No.2

Effect of Carbon on the Plastic Strain Ratio of Low Carbon Dual-Phase Steels

Woochang Jeong 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.1

The effect of carbon on the plastic strain ratio of low-carbon dual-phase steels was investigated in a seriesof low C-1.6 Mn–0.3Cr-0.2Mo-0.001B steels with carbon contents ranging from 0.021 to 0.048%. The rm valueof dual-phase steel could be increased by controlling both the carbon content and the martensite morphology. The highest rm value of 1.23 was obtained in 0.021% C steel annealed at 790 °C according to the typicalgalvannealing heat cycle. The martensite volume fraction was 5.4%, which was sufficient to eliminate the yield-point elongation in as-annealed steel, and this had little deteriorating effect on the rm value. The fine martensiteparticles between 0.5 µm and 2.0 µm in size were desirable for a high rm value in dual-phase steel.

Effect of Parameter Mismatch on Partial Synchronization in Coupled Chaotic Systems

Woochang Lim,Sang-Yoon Kim 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.II

We investigate the effect of parameter mismatch on partial synchronization in three coupled onedimensional maps. A completely synchronized attractor on the diagonal loses its transverse stability through a blowout bifurcation, and then partial synchronization may occur on an invariant plane. Due to the existence of positive local transverse Lyapunov exponents, the partially synchronized attractor becomes sensitive with respect to the variation of the mismatching parameter. Thus, in the presence of parameter mismatch, the invariant plane on which partial synchronization occurs is destroyed, and then an intermittent bursting from this plane occurs. To measure the degree of such parameter sensitivity, we introduce the parameter sensitivity exponent and characterize the parameter-mismatching effect on the intermittent bursting. The scaling exponent for the average interburst time is thus found to be given by the reciprocal of the parameter sensitivity exponent.

A Study on the Effect of Pair Check Cooperative Learning in Operating System Class

Woochang Shin 한국인터넷방송통신학회 2020 International Journal of Internet, Broadcasting an Vol.12 No.1

In the 4th Industrial Revolution, the competitiveness of the software industry is important, and as a solution to fundamentally secure the competitiveness of the software industry, education classes should be provided to educate high quality software personnel in educational institutions. Despite this social situation, software-related classes in universities are largely composed of competitive or individual learning structures. Cooperative learning is a learning model that can complement the problems of competitive and individual learning. Cooperative learning is more effective in improving academic achievement than individual or competitive learning. In addition, most learners have the advantage of having a more desirable self-image by having a successful experience. In this paper, we apply a pair check model, which is a type of cooperative learning, in operating system classes. In addition, the class procedure and instruction plan are designed to apply the pair check model. We analyze the test results to analyze the performance of the cooperative learning model.

Transition from a Strong to a Weak Coherence Resonance in Phase Neuron Models

Woochang Lim,Sang-Yoon Kim,Sunae Lee 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.1I

We study the dynamical response to noise in the one-dimensional type-I phase neuron model with a parameter (0 1) tuning the degree of multiplication in the noise. For = 0, the phase model is just the Adler equation, while it becomes the canonical type-I theta model for = 1. For the subthreshold case, the effect of noise on the oscillating characteristics is investigated by increasing from 0. A characteristic correlation time c has a maximum at some optimal noise intensity D, independently of . However, the phase model exhibits spectrally a coherent or incoherent response to noise, depending on the value of . For = 0, a spectrally coherent response to noise occurs in the Adler equation (i.e., noise-induced peaks appear in the output power spectrum) and is maximized near D. Thus, the Adler equation exhibits a “strong” coherence resonance (i.e., a maximal correlation occurs along with a spectral coherence resonance). However, as increases and passes a threshold value , such a spectrally coherent response ceases because the noise-induced peaks disappear from the output power spectrum for > . Thus, the phase model for > exhibits a “weak” coherence resonance (i.e., a maximal correlation occurs without any spectral coherence).

Strange Nonchaotic Spiking in the Quasiperiodically-forced Hodgkin-Huxley Neuron

Woochang Lim,김상윤 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.1

We study the transition from a silent state to a spiking state by varying the dc stimulus in the quasiperiodically-forced Hodgkin-Huxley neuron. For this quasiperiodically-forced case, a new type of strange nonchaotic (SN) spiking state is found to appear between the silent state and the chaotic spiking state as intermediate one. Using a rational approximation to the quasiperiodic forcing, we investigate the mechanism for the appearance of such an SN spiking state. We thus find that a smooth torus (corresponding to the silent state) is transformed into an SN spiking attractor via a phase-dependent saddle-node bifurcation. This is in contrast to the periodically-forced case where the silent state transforms directly to a chaotic spiking state. SN spiking states are characterized in terms of the interspike interval, so they are found to be aperiodic complex ones, as in the case of chaotic spiking states. Hence, aperiodic complex spikings may result from two dynamically different states with strange geometry (one is chaotic and the other one is nonchaotic).

Detection of Pathogenic Microbe on Protein Microarray Based on Imaging Ellipsometry

Woochang Lee(이우창),Yong-Wan Kim(김용완),Young Min Bae(배용민),Bum Suk Chun(천범석),Won Hong Lee(이원홍),Jeong-Woo Choi(최정우) 한국생물공학회 2004 한국생물공학회 학술대회 Vol.2004 No.4

Characterization of Stochastic Spiking Coherence in Coupled Neurons

Woochang Lim,Sang-Yoon Kim 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.II

We consider a large population of globally coupled subthreshold Morris-Lecar neurons. By varying the noise intensity $D$, we investigate numerically stochastic spiking coherence ({\it i.e.}, noise-induced coherence between neural spikings). As $D$ passes a threshold, a transition from an incoherent to a coherent state occurs. This coherent transition is described in terms of the ``thermodynamic'' order parameter $\cal{O}$, which concerns a macroscopic time-averaged fluctuation of the global potential. We note that such stochastic spiking coherence may be well visualized in terms of the raster plot of neural spikings ({\it i.e.}, spatiotemporal plot of neural spikings), which is directly obtained in experiments. To quantitatively measure the degree of stochastic spiking coherence (seen in the raster plot), we introduce a new type of ``spiking coherence measure,'' $M_s$, by taking into consideration the average contribution of (microscopic) local neural spikings to the (macroscopic) global membrane potential. Hence, the spiking coherence measure may be regarded as a ``statistical-mechanical'' measure. Through competition between the constructive and the destructive roles of noise, stochastic spiking coherence is found to occur over a large range of intermediate noise intensities and to be well characterized in terms of the mutually complementary quantities of $\cal{O}$ and $M_s$. Particularly, $M_s$ reflects the degree of stochastic spiking coherence seen in the raster plot very well.

Noise Effect on Weak Chaotic Synchronization in Coupled Invertible Systems

Woochang Lim,Sang-Yoon Kim 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.2

We investigate the noise eect on weak chaotic synchronization in coupled invertible systems such as coupled Henon maps and coupled pendula. Weakly stable synchronous chaotic attractors (SCAs) with positive local transverse Lyapunov exponents are sensitive with respect to variations in the noise intensity. To quantitatively characterize such noise sensitivity, we generalized the method proposed in coupled one-dimensional noninvertible maps to coupled high-dimensional invertible systems. Thus, we introduce a quantier, called the noise sensitivity exponent (NSE), to measure the \degree" of the noise sensitivity and to characterize the eect of noise on the bubbling and the riddling of a weakly stable SCA. Such a noise eect is found to be the same as the eect of parameter mismatch between subsystems.

On the Consequence of Blow-Out Bifurcations

Woochang Lim,Sang Yoon Kim,Sang-Yoon Kim 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.2

We investigate the consequence of a blow-out bifurcation of a chaotic attractor in an invariant line in a family of piecewise linear planar maps by changing a positive parameter controlling the reinjection. Through a supercritical blow-out bifurcation, a chaotic or hyperchaotic attractor, exhibiting on-o intermittency, is born, depending on the value of . For large , a hyperchaotic attractor with a positive second Lyapunov exponent appears. However, as the parameter decreases and passes a threshold value , a transition from hyperchaos to chaos occurs. Hence, for 0 < < a chaotic attractor with a negative second Lyapunov exponent is born. The sign of the second Lyapunov exponent of the newly-born intermittent attractor is found to be determined through competition between its laminar and bursting components. When the \strength" (i.e., a weighted second Lyapunov exponent) of the bursting component is larger (smaller) than that of the laminar component, a hyperchaotic (chaotic) attractor appears.