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Search Results: 1 - 10 of 175192 matches for " Dong H. Cha "
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Eavesdropping on Plant Volatiles by a Specialist Moth: Significance of Ratio and Concentration
Dong H. Cha,Charles E. Linn Jr.,Peter E. A. Teal,Aijun Zhang,Wendell L. Roelofs,Gregory M. Loeb
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0017033
Abstract: We investigated the role that the ratio and concentration of ubiquitous plant volatiles play in providing host specificity for the diet specialist grape berry moth Paralobesia viteana (Clemens) in the process of locating its primary host plant Vitis sp. In the first flight tunnel experiment, using a previously identified attractive blend with seven common but essential components (“optimized blend”), we found that doubling the amount of six compounds singly [(E)- & (Z)-linalool oxides, nonanal, decanal, β-caryophyllene, or germacrene-D], while keeping the concentration of other compounds constant, significantly reduced female attraction (average 76% full and 59% partial upwind flight reduction) to the synthetic blends. However, doubling (E)-4,8-dimethyl 1,3,7-nonatriene had no effect on female response. In the second experiment, we manipulated the volatile profile more naturally by exposing clonal grapevines to Japanese beetle feeding. In the flight tunnel, foliar damage significantly reduced female landing on grape shoots by 72% and full upwind flight by 24%. The reduction was associated with two changes: (1) more than a two-fold increase in total amount of the seven essential volatile compounds, and (2) changes in their relative ratios. Compared to the optimized blend, synthetic blends mimicking the volatile ratio emitted by damaged grapevines resulted in an average of 87% and 32% reduction in full and partial upwind orientation, respectively, and the level of reduction was similar at both high and low doses. Taken together, these results demonstrate that the specificity of a ubiquitous volatile blend is determined, in part, by the ratio of key volatile compounds for this diet specialist. However, P. viteana was also able to accommodate significant variation in the ratio of some compounds as well as the concentration of the overall mixture. Such plasticity may be critical for phytophagous insects to successfully eavesdrop on variable host plant volatile signals.
Automatic Multi-document Summarization Based on Clustering and Nonnegative Matrix Factorization
Park Sun,Cha ByungRea,An Dong
IETE Technical Review , 2010,
Abstract: In this paper, a novel summarization method that uses nonnegative matrix factorization (NMF) and the -clus--tering method is introduced to extract meaningful sentences relevant to a given query. The proposed method decomposes a sentence into the linear combination of sparse nonnegative semantic features so that it can represent a sentence as the sum of a few semantic features that are comprehensible intuitively. It can improve the quality of document summaries because it can avoid extracting those sentences whose similarities with the query are high but that are meaningless by using the similarity between the query and the semantic features. In addition, the proposed approach uses the clustering method to remove noise and avoid the biased inherent semantics of the documents being reflected in summaries. The method can -ensure the coherence of summaries by using the rank score of sentences with respect to semantic -features. The experimental results demonstrate that the proposed method has better performance than other -methods that use the thesaurus, the latent semantic analysis (LSA), the K-means, and the NMF.
Investigative Report for Economists; “Prediction of Stock Market” and Functional “Invisible Hand” and “Law of Supply and Demand”  [PDF]
Deoksoo Cha
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.66120
Abstract: This paper is an innovative scientific report about the following economic problems. It considers why the stock price cannot be predicted and the function of the invisible hand and the law of supply and demand. Incidentally, it is possible to solve these by other science, for example, the systems’ analysis theory in engineering. Therefore, economic science is very rational or systematic economic systems are not black boxes. It cannot be solved with traditional science but with other science, and proved with simulations. This scientific research has the potential to be sensational for economic development; therefore, scientists across the world must be informed about its solution.
The Advanced Solution for Mission of Complexity  [PDF]
Deoksoo Cha
Journal of Modern Physics (JMP) , 2017, DOI: 10.4236/jmp.2017.87072
Abstract: This paper provides a clarification of the advanced solution for the mission of complexity in science, which was previously published in 2015; but the new solution is too difficult to scientists; for this, this paper describes the academic reasoning and the relevant scientific background behind solution. Moreover, it shows that the solution can be simulated the complex systems by the computer program MATLAB Simulink or an analog-type simulator under virtual circumstances. Thus, this paper verifies that the new solution has validity and superiority; additionally, it must replace the established older chaos theory with the advanced solution in future, so that this new solution is disadvantageous to many chaos physicists and the famous organization SFI, and others. However, they must suspend their work on complexity, because the complexity is a solvable problem in science.
A Study on Effective System for Harbor Container Delivery & Cargo Work Automatuion  [PDF]
Dong-Hoon Kim, Jun-Yeob Song, Seung-Ho Lee, Il-Yong Kang, Suk-Keun Cha
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.28074
Abstract: In this article, we have attempted to analyze current situation and the problem of domestic and overseas harbor container delivery & cargo work automation centered on major harbors and to suggest effective way to deal with the issue in order to improve the productivity of container cargo work per crane, the major index of productivity of high value-added shipbuilding industry. In particular, we have suggested the way to realize effective automation system that can improve the efficiency of harbor container delivery & cargo work through the development of high-tech measuring automation technology using microwave radar and applied design that have broken away from traditional automation system and traditional problems such as dependence on manual work and the problem of laser method in which workers cannot identify laser beam under sunlight and workers’ eyesight can be weakened by being exposed to laser beam.
Topological Defects, Orientational Order, and Depinning of the Electron Solid in a Random Potential
Min-Chul Cha,H. A. Fertig
Physics , 1994, DOI: 10.1103/PhysRevB.50.14368
Abstract: We report on the results of molecular dynamics simulation (MD) studies of the classical two-dimensional electron crystal in the presence disorder. Our study is motivated by recent experiments on this system in modulation doped semiconductor systems in very strong magnetic fields, where the magnetic length is much smaller than the average interelectron spacing $a_0$, as well as by recent studies of electrons on the surface of helium. We investigate the low temperature state of this system using a simulated annealing method. We find that the low temperature state of the system always has isolated dislocations, even at the weakest disorder levels investigated. We also find evidence for a transition from a hexatic glass to an isotropic glass as the disorder is increased. The former is characterized by quasi-long range orientational order, and the absence of disclination defects in the low temperature state, and the latter by short range orientational order and the presence of these defects. The threshold electric field is also studied as a function of the disorder strength, and is shown to have a characteristic signature of the transition. Finally, the qualitative behavior of the electron flow in the depinned state is shown to change continuously from an elastic flow to a channel-like, plastic flow as the disorder strength is increased.
Orientational Order and Depinning of the Disordered Electron Solid
Min-Chul Cha,H. A. Fertig
Physics , 1994, DOI: 10.1103/PhysRevLett.73.870
Abstract: We study the ground state of two-dimensional classical electron solids under the influence of modulation-doped impurities by using a simulated annealing molecular dynamics method. By changing the setback distance as a parameter, we find that in the strong disorder limit the ground state configuration contains both isolated dislocations and disclinations, whereas in the weak disorder regime only dislocations are present. We show, via continuum elasticity theory, that the ground state of the lattice should be unstable against a proliferation of free disclinations above a critical dislocation density. Associated with this, the behavior of the threshold electric field as a function of the setback distance changes.
Peak Effect and the Transition from Elastic to Plastic Depinning
Min-Chul Cha,H. A. Fertig
Physics , 1998, DOI: 10.1103/PhysRevLett.80.3851
Abstract: We demonstrate for the first time an observation of the peak effect in simulations of magnetic vortices in a superconductor. The shear modulus $c_{66}$ of the vortex lattice is tuned by adding a fictitious {attractive} short range potential to the usual long-range repulsion between vortices. The peak effect is found to be most pronounced in low densities of pinning centers, and is always associated with a transition from elastic to plastic depinning. The simulations suggest in some situations that over a range of values of $c_{66}$ the production of lattice defects by a driving force enhances the pinning of the lattice.
Multimodal sparse representation learning and applications
Miriam Cha,Youngjune Gwon,H. T. Kung
Computer Science , 2015,
Abstract: Unsupervised methods have proven effective for discriminative tasks in a single-modality scenario. In this paper, we present a multimodal framework for learning sparse representations that can capture semantic correlation between modalities. The framework can model relationships at a higher level by forcing the shared sparse representation. In particular, we propose the use of joint dictionary learning technique for sparse coding and formulate the joint representation for concision, cross-modal representations (in case of a missing modality), and union of the cross-modal representations. Given the accelerated growth of multimodal data posted on the Web such as YouTube, Wikipedia, and Twitter, learning good multimodal features is becoming increasingly important. We show that the shared representations enabled by our framework substantially improve the classification performance under both unimodal and multimodal settings. We further show how deep architectures built on the proposed framework are effective for the case of highly nonlinear correlations between modalities. The effectiveness of our approach is demonstrated experimentally in image denoising, multimedia event detection and retrieval on the TRECVID dataset (audio-video), category classification on the Wikipedia dataset (image-text), and sentiment classification on PhotoTweet (image-text).
Weakly Nonlinear Stability Analysis of a Thin Magnetic Fluid during Spin Coating
Cha'o-Kuang Chen,Dong-Yu Lai
Mathematical Problems in Engineering , 2010, DOI: 10.1155/2010/987891
Abstract: This paper investigates the stability of a thin electrically conductive fluid under an applied uniform magnetic filed during spin coating. A generalized nonlinear kinematic model is derived by the long-wave perturbation method to represent the physical system. After linearizing the nonlinear evolution equation, the method of normal mode is applied to study the linear stability. Weakly nonlinear dynamics of film flow is studied by the multiple scales method. The Ginzburg-Landau equation is determined to discuss the necessary conditions of the various critical flow states, namely, subcritical stability, subcritical instability, supercritical stability, and supercritical explosion. The study reveals that the rotation number and the radius of the rotating circular disk generate similar destabilizing effects but the Hartmann number gives a stabilizing effect. Moreover, the optimum conditions can be found to alter stability of the film flow by controlling the applied magnetic field.
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