Soon-Hyung Yook

• Ph. D
• Professor (Associate) at Kyung Hee University

When an unprecedented infectious disease with high mortality and transmissibility emerges, immediate access to vaccines or medicines is often unavailable. Therefore, many health authorities rely on non-pharmaceutical interventions, such as contact tracing combined with isolation, to mitigate the spread of the disease. However, contact tracing is ge...

To understand how competition affects the diversity of information, we study the social contagion model introduced by Halvorsen-Pedersen-Sneppen (HPS) [G. S. Halvorsen, B. N. Pedersen, and K. Sneppen, Phys. Rev. E 103, 022303 (2021)] on one-dimensional (1D) and two-dimensional (2D) static networks. By mapping the information value to the height of...

The real epidemic spreading has generally two different types of transmission routes. One is the random anonymous infection and the other one is the transmission through regular and fixed contacts. If the infectious disease has high mortality and there is no available vaccine or medicine, then many health authorities rely on the non-pharmaceutical...

We study the record statistics in the Korean housing market. To characterize the statistical properties of records, we analyze the record rate and the expected number of records for the transaction price of apartments and the volatility. From the numerical analysis, we find that the record rate of price in the overheated region is well described by...

We study the phase transition of the degree-weighted majority vote (DWMV) model on Erdős-Rényi networks (ERNs) and scale-free networks (SFNs). In this model, a weight parameter α adjusts the level of influence of each node on its connected neighbors. Through the Monte Carlo simulations and the finite-size scaling analysis, we find that the DWMV mod...

We study the origin of the log-normal popularity distribution of trending memes observed in many real social networks. Based on a biological analogy, we introduce a fitness of each meme, which is a natural assumption based on sociological reasons. From numerical simulations, we find that the relative popularity distribution of the trending memes be...

We study the scaling of the price fluctuation in the Korean housing market. From the numerical analysis, we show that the normalized return distribution of the housing price, P(r), has a fat-tail and is well approximated by a power-law, P(r) ~ r−(α+1), with α ≃ 3 for the whole data set. However, if we divide the data into groups based on the tradin...

We investigate the behavior of two different order parameters for the Kuramoto model in the desynchronized phase. Since the primary role of the order parameter is to distinguish different phases, we focus on the ability to discern the desynchronized phase from the synchronized one on complex networks with the size N. From the exact derivation of th...

We study the mean first passage time (MFPT) of true self-avoiding walks (TSAWs) on various networks as a measure of searching efficiency. From the numerical analysis, we find that the MFPT of TSAWs, τTSAW, approaches the theoretical minimum τth/N=12 on synthetic networks whose degree-degree correlations are positive. On the other hand, for biased r...

Spatial evolutionary games have mainly been studied on a single, isolated network. However, in real world systems, many interaction topologies are not isolated but many different types of networks are inter-connected to each other. In this study, we investigate the spatial evolutionary public goods game (SEPGG) on double-layered random networks (DR...

Previous studies showed that the meme popularity distribution is described by a heavy-tailed distribution or a power-law, which is a characteristic feature of the criticality. Here, we study the origin of the criticality on non-growing and growing networks based on the competition induced criticality model. From the direct Mote Carlo simulations an...

Online social media such as Twitter are widely used for mining public opinions and sentiments on various issues and topics. The sheer volume of the data generated and the eager adoption by the online-savvy public are helping to raise the profile of online media as a convenient source of news and public opinions on social and political issues as wel...

We study the modular structure of financial network based on the transfer entropy (TE). From the comparison with the obtained modular structure using the cross-correlation (CC), we find that TE and CC both provide well organized modular structure and the hierarchical relationship between each industrial group when the time scale of the measurement...

We study the spatial evolutionary prisoner's dilemma game with updates of imitation max on triangular, hexagonal, and square lattices. We use the weak prisoner's dilemma game with a single parameter b. Due to the competition between the temptation value b and the coordination number z of the base lattice, a greater variety of percolation properties...

To understand how the jamming on real communication networks depends on node capacity, we study the traffic model with heterogeneous node capacity. In this model, each movable packet takes a biased random walk and the capacity of a node with degree k is given as C(k) ∼ k x with a tunable parameter x. Each packet disappears when it arrives at the pr...

Online social media such as Twitter are widely used for mining public opinions and sentiments on various issues and topics. The sheer volume of the data generated and the eager adoption by the online-savvy public are helping to raise the profile of online media as a convenient source of news and public opinions on social and political issues as wel...

We study the spatial evolutionary public goods game (SEPGG) with voluntary or optional participation on a complete graph (CG) and on dense networks. Based on analyses of the SEPGG rate equation on finite CG, we find that SEPGG has two stable states depending on the value of multiplication factor r, illustrating how the "tragedy of the commons" and...

We study the topological properties of the information transfer networks (ITN) of the global financial market indices for six different periods. ITN is a directed weighted network, in which the direction and weight are determined by the transfer entropy between market indices. By applying the threshold method, it is found that ITN crossovers from t...

To understand the effect of generalized infection processes, we suggest and study the core contact process (CCP) on complex networks. In CCP an uninfected node is infected when at least k different infected neighbors of the node select the node for the infection. The healing process is the same as that of the normal CP. It is analytically and numer...

To understand the dependence of phase-transition natures in explosive percolations on space dimensions, the number n_{cut} of cutting bonds (sites) and the fractal dimension d_{CSC} of the critical spanning cluster (CSC) for the six different models introduced in Phys. Rev. E 86, 051126 (2012) are studied on two- and three-dimensional lattices. It...

To understand the effects of nonidentical processing elements (PEs) on parallel discrete-event simulation (PDES) schemes, two stochastic growth models, the restricted solid-on-solid (RSOS) model and the Family model, are investigated by simulations. The RSOS model is the model for the PDES scheme governed by the Kardar-Parisi-Zhang equation (KPZ sc...

We study heterogeneous k-core (HKC) percolation with a general mixture of the threshold k, with k_{min}=2 on random networks. Based on the local tree approximation, the scaling behaviors of the percolation order parameter P_{∞}(p) are analytically obtained for general distributions of the threshold k. The analytic calculations predict that the gene...

Transport properties in random and scale-free (SF) networks are studied by analyzing the betweenness centrality (BC) distribution P(B) in the minimum spanning trees (MSTs) and infinite incipient percolation clusters (IIPCs) of the networks. It is found that P(B) in MSTs scales as P(B)∼B^{-δ}. The obtained values of δ are classified into two differe...

We study the effect of the topology of industrial relationship (IR) between the companies in a stock exchange market on the universal features in the market. For this we propose a stochastic model for stock exchange markets based on the behavior of technical traders. From the numerical simulations we measure the return distribution, P(R), and the a...

In this letter we propose two general models for paradigm shift, deterministic propagation model (DM) and stochastic propagation model (SM). By defining the order parameter $m$ based on the diversity of ideas, $\Delta$, we study when and how the transition occurs as a cost $C$ in DM or an innovation probability $\alpha$ in SM increases. In addition...

Agglomerative percolation (AP) on the Bethe lattice and the triangular cactus is studied to establish the exact mean-field theory for AP. Using the self-consistent simulation method based on the exact self-consistent equations, the order parameter P∞ and the average cluster size S are measured. From the measured P∞ and S, the critical exponents βk...

Competition between a complex system's constituents and a corresponding reward mechanism based on it have profound influence on the functioning, stability, and evolution of the system. But determining the dominance hierarchy or ranking among the constituent parts from the strongest to the weakest -- essential in determining reward or penalty -- is...

The site and bond explosive percolation models are carefully defined and studied on a square lattice. From the cluster distribution function and the behavior of the second largest cluster, it is shown that the duality in which the transition is discontinuous exists for the pairs of the site model and the corresponding bond model which relatively en...

To establish the bond-site duality of explosive percolations in two dimensions, the site and bond explosive-percolation models are carefully defined on a square lattice. By studying the cluster distribution function and the behavior of the second largest cluster, it is shown that the duality in which the transition is discontinuous exists for the p...

The conductivity of random resistor networks composed from percolating clusters of two-dimensional (2D) stick systems with anisotropic alignments is analyzed by using a finite-size scaling analysis for comparison to the conductivity of single-walled carbon-nanotube bundle film networks. For the conductivity analysis, we first calculate the critical...

We study the agglomerative percolation (AP) models on the Bethe lattice and the triangular cactus to establish the exact mean-field theory for AP. Using the self-consistent simulation method, based on the exact self-consistent equation, we directly measure the order parameter $P_{\infty}$ and average cluster size $S$. From the measured $P_{\infty}$...

Based on the self-consistent equations of the order parameter $P_\infty$ and the mean cluster size $S$, we develop a novel self-consistent simulation (SCS) method for arbitrary percolation on the Bethe lattice (infinite homogeneous Cayley tree). By applying SCS to the well-known percolation models, random bond percolation and bootstrap percolation,...

Motivated by biological aging dynamics, we introduce a network evolution model for social interaction networks. In order to study the effect of social interactions originating from biological and sociological reasons on the topological properties of networks, we introduce the activitydependent rewiring process. From the numerical simulations, we sh...

In this study, we investigate how the heterogeneous site size distribution affects the behavior of the branch size distribution of critical trees. By assuming a power-law, P(s) ∼ s −α , for the site size distribution, we find that the exponent τ for the branch size distribution is smaller than that of a critical tree when α < 3. When α ≥ 3, we find...

We study the effects of the underlying topologies on a single feature perturbation imposed to the Axelrod model of consensus formation. From the numerical simulations we show that there are successive updates which are similar to avalanches in many self-organized criticality systems when a perturbation is imposed. We find that the distribution of a...

We study a self-organized scale-free network model generated using the Merging-and-Creation dynamics with preferential attachment. We show analytically that the introduction of preferential attachment has minimal impact on the steady-state degree distribution. However, we find also that the preferential attachment gives rise to a hierarchical modul...

Exponential random graph theory is the complex network analog of the canonical ensemble theory from statistical physics. While it has been particularly successful in modeling networks with specified degree distributions, a naive model of a clustered network using a graph Hamiltonian linear in the number of triangles has been shown to undergo an abr...

We study the site percolation under Achlioptas process (AP) with a product rule in a $2-dimensional$ (2D) square lattice. From the measurement of the cluster size distribution, $P_s$, we find that $P_s$ has a very robust power-law regime followed by a stable hump near the transition threshold. Based on the careful analysis on the $P_s$ distribution...

The effect of shortcuts on the task completion landscape in parallel discrete-event simulation (PDES) is investigated. The morphology of the task completion landscape in PDES is known to be described well by the Langevin-type equation for nonequillibrium interface growth phenomena, such as the Kardar-Parisi-Zhang equation. From the numerical simula...

We numerically study an equilibrium network model, generated via a graph Hamiltonian, that exhibits a power-law degree distribution P(k)similar to k(-gamma) with gamma approximate to 1.5 in the thermodynamic limit. While the degree exponent, gamma, is equal to the one found in the Merging-Creation (MC) model, we find that the detailed topological p...

Using the percolation theory, we study the underlying mechanism in the formation of single-walled nanotube bundles with uniform diameter. By applying the cluster repulsion process to stick percolation, we find that the transition becomes explosive. To understand the transition nature, we first investigate the scaling behavior of transition interval...

We study the dynamical properties of the propagation of innovation on a two-dimensional lattice, random network, scale-free network, and Cayley tree. In order to investigate the diversity of technological level, we study the scaling property of width, W(N,t), which represents the root mean square of the technological level of agents. Here, N is the...

We study the statistical properties of sampled networks by using a biased random walker on as-sortative networks. In the biased random walk sampling, all the nodes visited by the biased random walker and the links that connect any pair of visited nodes are sampled. Here, the probability that a walker moves to one of its nearest neighbor depends on...

We investigate how the largest synchronized connected component (LSCC) is formed and evolves to achieve a global synchronization on complex networks using Kuramoto model. In this study we use two different networks, Erdösi-Rényi network and Barabási-Albert network. From the finite-size scaling analysis, we find that the scaling exponents for the pe...

Information search is closely related to the first-passage property of diffusing particle. The physical properties of diffusing particle is affected by the topological structure of the underlying network. Thus, the interplay between dynamical process and network topology is important to study information search on complex networks. Designing an eff...

We propose a novel centrality measure based on the dynamical properties of a biased random walk to provide a general framework for the centrality of vertex and edge in scale-free networks (SFNs). The suggested centrality unifies various centralities such as betweenness centrality (BC), load centrality (LC) and random walk centrality (RWC) when the...

We study two weight-driven information spreading models for financial market. In these models, we find that the activity threshold below which the ‘financial crash’ occurs can be increased by uneven distribution of information weight, compared with Eguíluz and Zimmermann model [V.M. Eguíluz, M.G. Zimmermann, Phys. Rev. Lett. 85 (2000) 5659]. We als...

We study a microscopic model for financial markets on complex networks, motivated by the dynamics of agents and their structure of interaction. The model consists of interacting agents (spins) with local ferromagnetic coupling and global antiferromagnetic coupling. In order to incorporate more realistic situations, we also introduce an external fie...

We study a microscopic model for price formation in nancial markets on a two-dimensional lattice, motivated by the dynamics of agents. The model consists of interacting agents (spins) with local and global couplings. The local interaction denotes the tendency of agents to make the same decision as their interacting partners. On the other hand, the...

Detecting community structures and hierarchy among communities have been one of the most attractive research topics in complex network studies. In this study we regard each protein as an oscillator which interacts with its neighboring proteins. In order to define the hierarchy among the functional classes based on the synchronizability of each func...

We study the novel reaction-diffusion process of three-species on scale-free networks, which is significantly different from the numerical calculation manipulated on regular and small-world lattices. The inverse particle density for three-species process scales as the power-law behavior with alpha=1.5 for gamma>3 . However we find that the inverse...

We study an agent based microscopic model for price formation in financial markets on various topologies motivated by the dynamics of agents. The model consists of interacting agents (spins) with localand global couplings. The local interaction denotes the tendency of agents to make the same decision with their interacting partners. On the other ha...

We study dynamical scaling of flux fluctuation sigma(t) from the one-random-walker model on regular lattices and complex networks and compare it to the surface width W(t) of a corresponding growth model. On the regular lattices, we analytically show that sigma(t) undergoes a crossover from the nontrivial scaling regime to the trivial one by increas...

We study the statistical properties of the sampled networks by a random walker. We compare topological properties of the sampled networks such as degree distribution, degree-degree correlation, and clustering coefficient with those of the original networks. From the numerical results, we find that most of topological properties of the sampled netwo...

We show how effectively the diffusive capture processes (DCP) on complex networks can be applied to information search in the networks. Numerical simulations show that our method generates only 2% of traffic compared with the most popular flooding-based query-packet-forwarding (FB) algorithm. We find that the average searching time, $ $, of the our...

Dynamical scalings for the end-to-end distance $R_{ee}$ and the number of distinct visited nodes $N_v$ of random walks (RWs) on finite scale-free networks (SFNs) are studied numerically. $\left< R_{ee} \right>$ shows the dynamical scaling behavior $\left<R_{ee}({\bar \ell},t)\right>= \bar{\ell}^\alpha (\gamma, N) g(t/\bar{\ell}^z)$, where $\bar{\el...

For many externally driven complex systems neither the noisy driving force, nor the internal dynamics are a priori known. Here we focus on systems for which the time-dependent activity of a large number of components can be monitored, allowing us to separate each signal into a component attributed to the external driving force and one to the intern...

We study the statistical properties of the sampled networks by a random walker. We compare topological properties of the sampled networks such as degree distribution, degree-degree correlation, and clustering coefficient with those of the original networks. From the numerical results, we find that most of topological properties of the sampled netwo...

We study the dynamical properties of a diffusing lamb captured by a diffusing lion on the complex networks with various sizes of N. We find that the lifetime {T} of a lamb scales as {T} approximately N and the survival probability S(N-->infinity, t) becomes finite on scale-free networks with degree exponent gamma > 3. However, S(N, t) for gamma < 3...

We study the dynamical properties of a diffusing lamb captured by a diffusing lion on the complex networks with various sizes of $N$. We find that the life time $ of a lamb scales as \sim N$ and the survival probability $S(N\to \infty,t)$ becomes finite on scale-free networks with degree exponent $\gamma>3$. However, $S(N,t)$ for $\gamma<3$ has a l...

We numerically study the dynamic properties of diffusing lamb captured by diffusing lion on the complex networks. We find that the survival probability S(t) of a lamb decays exponentially on the complex networks including scale-free networks whose degree distribution follows P(k) ˜k^- gamma. We also find that the average life time depends on the si...

We study the influence of topology on the dynamical properties of a diffusion process which can be described by a diffusion equation with multiplicative noise on a complex network. From numerical simulations we find that the fluctuation of the incoming mass on a given node of network scales with the average incoming mass, or flux, in a topology-dep...

Self-similar networks with scale-free degree distribution have recently attracted much attention, since these apparently incompatible properties were reconciled in [C. Song, S. Havlin, and H. A. Makse, Nature 433, 392 (2005)] by an appropriate box-counting method that enters the measurement of the fractal dimension. We study two genetic regulatory...

We study the synchronization of Rössler oscillators as prototypes of chaotic systems on scale-free complex networks. As it turns out, the underlying topology crucially affects the global synchronization properties. In particular, we show that the existence of loops facilitates the synchronizability of the system, whereas Rössler oscillators do not...

Self-similar networks with scale-free degree distribution have recently attracted much attention, since these apparently incompatible properties were reconciled in a paper by Song et al. by an appropriate box-counting method that enters the measurement of the fractal dimension. We study two genetic regulatory networks ({\it Saccharomyces cerevisiae...

Understanding the mechanisms governing the behavior of complex networks is a prerequisite for characterizing complex systems. Frequently, networks are modelled as unweighted graphs in which each link has the same strength. However, for many real networks appearing in biological, technological and economic systems, each link has a specific weight, a...

For many externally driven complex systems neither the noisy driving force, nor the internal dynamics are a priori known. Here we focus on systems for which the time dependent activity of a large number of components can be monitored, allowing us to separate each signal into a component attributed to the external driving force and one to the intern...

Intracellular signal transduction occurs through cascades of reactions involving dozens of proteins that transmit signals from the cell surface, through a crowded cellular environment filled with organelles and a filamentous cytoskeleton, to specific targets. Numerous signaling molecules are immobilized or transiently bound to the cytoskeleton, yet...

The elucidation of the cell's large-scale organization is a primary challenge for post-genomic biology, and understanding the structure of protein interaction networks offers an important starting point for such studies. We compare four available databases that approximate the protein interaction network of the yeast, Saccharomyces cerevisiae, aimi...

Networks with complex topology describe systems as diverse as the cell or the World Wide Web. The emergence of these networks is driven by self-organizing processes that are governed by simple but generic laws. In the last three years it became clear that many complex networks, such as the Internet, the cell, or the world wide web, share the same l...

Network generators that capture the Internet's large-scale topology are crucial for the development of efficient routing protocols and modeling Internet traffic. Our ability to design realistic generators is limited by the incomplete understanding of the fundamental driving forces that affect the Internet's evolution. By combining several independe...

Network generators that capture the Internet's large-scale topology are crucial for the development of efficient routing protocols and modeling Internet traffic. Our ability to design realistic generators is limited by the incomplete understanding of the fundamental driving forces that affect the Internet's evolution. By combining the most extensiv...

Many biological, ecological, and economic systems are best described by weighted networks, as the nodes interact with each other with varying strength. However, most evolving network models studied so far are binary, the link strength being either 0 or 1. In this paper we introduce and investigate the scaling properties of a class of models which a...

Many biological, ecological and economic systems are best described by weighted networks, as the nodes interact with each other with varying strength. However, most network models studied so far are binary, the link strength being either 0 or 1. In this paper we introduce and investigate the scaling properties of a class of models which assign weig...

Growth models for vapor depositions in which evaporation and deposition can occur, both at a randomly chosen column and at its nearest neighbor columns (NNCs), are studied by Monte Carlo simulations. The growth processes in these models are determined by comparing local chemical potentials of the chosen column and its NNCs to the chemical potential...

A growth model in quenched random media which has the mean-field-like driving force F and local avalanche processes simultaneously and explicitly has been suggested and studied by simulations. It has been found that this model belongs to the same universality class as the directed percolation depinning models. The critical moving regime of the sugg...

Restricted solid-on-solid (RSOS) models with finite-distance hoppings are studied. A randomly dropped particle is allowed to hop to find the nearest site satisfying the RSOS condition within a finite hopping distance . If the particle can find such a site within the distance , then the growth is permitted at that site. If the particle cannot find t...

To test the corrected scaling relation alpha+z=4-3delta of the conserved Kardar-Parisi-Zhang (CKPZ) equation suggested by Janssen [Phys. Rev. Lett. 78, 1082 (1997)], a stochastic growth model that follows the CKPZ equation with the conserved noise is restudied. We have found a consistent nonzero correction term delta, which is somewhat larger than...

Modified Sneppen models in which local avalanches of the size s less than or equal to s(c) are only allowed are suggested and studied by simulations. The models with fixed cutoff size s(c)'s belong to the same universality class as the Sneppen A model, while the models with s(c) proportional to substrate size L (s(c) proportional to L) are critical...

A conserved growth model with a constraint on neighboring interface heights in substrate dimensions d(s) = 2,3,4,5 is investigated. A randomly dropped particle is allowed to hop to the nearest site satisfying the restricted solid-on-solid condition. The scaling properties of the surface in d(s) = 2,3, and 4 are consistent with those of the continuu...