• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.584-588
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• 2003

In this paper, we propose a method to avoid obstacles that have unstable limit cycles in a Hyperchaos trajectory surface. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. When a chaos robot meets an obstacle in a hyper-chaos equation trajectory, the obstacle reflects the robot. We also show computer simulation result of hyperchaos equation trajectories with one or more Van der Pol obstacles.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2717-2722
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• 2009

The use of the classification and regression tree (CART) methodology was studied in a quantitative structure-activity relationship (QSAR) context on a data set consisting of the binding affinities of 39 imidazobenzodiazepines for the α1 benzodiazepine receptor. The 3-D structures of these compounds were optimized using HyperChem software with semiempirical AM1 optimization method. After optimization a set of 1481 zero-to three-dimentional descriptors was calculated for each molecule in the data set. The response (dependent variable) in the tree model consisted of the binding affinities of drugs. Three descriptors (two topological and one 3D-Morse descriptors) were applied in the final tree structure to describe the binding affinities. The mean relative error percent for the data set is 3.20%, compared with a previous model with mean relative error percent of 6.63%. To evaluate the predictive power of CART cross validation method was also performed.

• Journal of the Korean Data and Information Science Society
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• v.23 no.3
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• pp.587-593
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• 2012

We study Bayesian estimates for finite population proportions in multinomial problems. To do this, we consider a three-stage hierarchical Bayesian model. For prior, we use Dirichlet density to model each cell probability in each cluster. Our method does not require complicated computation such as Metropolis-Hastings algorithm to draw samples from each density of parameters. We draw samples using Gibbs sampler with grid method. We apply this algorithm to a couple of simulation data under three scenarios and we estimate the finite population proportions using two kinds of approaches We compare results with the point estimates of finite population proportions and their standard deviations. Finally, we check the consistency of computation using differen samples drawn from distinct iterates.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.289-293
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• 2005

this paper, we introduce a secure communication method using complex system. We make a complex system with the n-double scroll or Chua's oscillator. The Complex system is created by applying identical n0double scroll or non-identical n-double scroll and Chua's oscillator with weak soupled method to each cell. In order to secure communication, we have synthesizing the desired information with a complex system circuit by adding the information signal to the hyper-chaos signal. And then, transmitting the synthesized signal to the ideal channel, we confirm secure communication by separating the information signal and the complex system signal in the receiver.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2005.11a
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• pp.197-204
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• 2005

In this paper, we propose a method to an obstacle avoidance of chaotic robots that have unstable limit cycles in a chaos trajectory surface in the ubiquitous environment. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. We also show computer simulation results of Chua's equation, Lorenz equation, Hamilton and Hyper-chaos equation trajectories with one or more Van der Pol as an obstacles. We proposed and verified the results of the method to make the embedding chaotic mobile robot to avoid with the chaotic trajectory in any plane.

• ETRI Journal
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• v.40 no.6
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• pp.813-823
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• 2018

In existing mobile computing environments, users need to choose between their privacy and the services that they can receive from an application. However, existing mobile platforms do not allow users to perform such trade-offs in a fine-grained manner. In this study, we investigate whether users can effectively make utility-privacy trade-offs when they are provided with a multilevel privacy control method that allows them to recognize the different quality of service that they will receive from an application by limiting the disclosure of their private information in multiple levels. We designed a research model to observe users' utility-privacy trade-offs in accordance with the privacy control methods and other factors such as the trustworthiness of an application, quality level of private information, and users' privacy preferences. We conducted a user survey with 516 participants and found that, compared with the existing binary privacy controls, both the service utility and the privacy protection levels were significantly increased when the users used the multilevel privacy control method.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.3
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• pp.37-44
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• 2023

In the future society, a means to verify the identity of the information owner is required at the beginning of most services that the information owner encounters, and the emergence and gradual spread of digital identification that proves the identity of the information owner is essential. In addition, as the utilization value of personal information increases, discussions on how to provide personal information are active. Therefore, there is a need for a personal information management method necessary for building a hyper-connected society that is safe from various hacking, forgery, alteration, and theft by allowing the owner to directly manage and provide personal information management. In this study, a decentralized identity information management model that overcomes the problems and limitations of the centralized identity management method of personal information and manages and selectively provides personal information by the information owner himself and implemented a smart personal information provision system(SPIPS: Smart Personal Information Provision System) using a smartphone.

• Communications for Statistical Applications and Methods
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• v.30 no.3
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• pp.245-258
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• 2023

This study proposes a modification to the objective function of the support vector machine for the linearly non-separable case of a binary classifier y_i ∈ {-1, 1}. The modification takes into account the position of each data item x_i from its corresponding class centroid. The resulting optimization function involves the centroid mean vector, and the spread of data besides the support vectors, which should be minimized by the choice of hyper-plane β. Theoretical assumptions have been tested to derive an optimal separable hyperplane that yields the minimal misclassification rate. The proposed method has been evaluated using simulation studies and real-life COVID-19 patient outcome hospitalization data. Results show that the proposed method performs better than the classical linear SVM classifier as the sample size increases and is preferred in the presence of correlations among predictors as well as among extreme values.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.74.1-74.1
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• 2019

We present the distance measurements of two spiral galaxies NGC 4517, NGC 4592, and neighboring dwarf galaxies found in Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) wide field survey data. Distances to NGC 4517 and NGC 4592 are measured by the Tip of the Red Giant Branch method from archival Hubble Space Telescope data; 9.00^+0.094_-0.260 Mpc for NGC 4517 and 8.90^+0.256_-0.060 Mpc for NGC 4592. The spatial distance between NGC 4517 and NGC 4592 is 300 kpc, which is close enough for them to be considered as a group (NGC 4517 group). Using resolved stellar photometry and Surface Brightness Fluctuation (SBF) method with HSC-SSP data, we estimate the distances to three other dwarf galaxies and confirm that they are members of the group. Velocities of three of the galaxies in the NGC 4517 group show that this group is one of the galaxy groups in the near side of the Virgo Cluster infall region.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.269-276
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• 2017

In this study, a test was conducted to examine the effects of micro-needle therapy (MTS) and cosmetics containing spirulina on improving the skin tone, skin hydration, hyper-pigmentation, and fine lines of middle-aged women in their 40s and 50s and to propose an effective skin care method. The subjects were divided into a control group of eight people who used serum and cream mask that does not contain MTS and spirulina, and an experimental group who used serum and cream containing MTS and spirulina. The test was conducted with six 30-minute sessions for one week. The change in skin was measured over three times in the week of the test, after six weeks of the test, and two weeks after the test had finished. The result showed that after six weeks of the test, in the experimental group, the skin tone (color brightness, saturation brightness, skin brightness) and moisture showed a significant increase (p<0.05), while the number of small hyper-pigmentation and large hyper-pigmentation, as well as the length of crow's feet, melanin, erythema showed a significant reduction (p<0.05). No significant differences in fine lines under the eyes and length of crow's feet were observed. Two weeks after the test was finished, the experimental group showed a significant decrease in the length of crow's feet and melanin (p<0.05), and a significant increase in skin brightness and moisture (p<0.05). Even after the test was completed, the skin brightness, fine lines, melanin, and moisture improved continuously. In conclusion, skin care using MTS and cosmetics containing spirulina was more effective on improving the skin tone, hydration, hyper-pigmentation, and fine lines, than skin care without using them.