• Journal of Internet Computing and Services
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• v.7 no.6
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• pp.87-103
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• 2006

Advances in computer and network technology provide new computing environment that were only possible with supercomputers before. In order to provide the environment, a distributed runtime system has to be provided, but most of the conventional distributed runtime systems lack in providing dynamic and flexible system reconfiguration depending on workload variance, due to a static architecture of fixed master node and slave working nodes. This paper proposes and implements a new model for distributed job allocation and management which is a distributed runtime system is P2P environment for flexible and dynamic system reconfiguration. The implemented systems enables job program transfer and management, remote compile and execution among cooperative developers based on P2P standard protocol Jxta platform. Since it makes dynamic and flexible system reconfiguration possible, the proposed method has some advantages in that it can collect and utilize idle computing resources immediately at a needed time for distributed job processing. Moreover, the implemented system's effectiveness and performance increase are shown by applying and processing the crawler jobs, in a distributed way, for collecting a large amount of data needed for internet search.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.8
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• pp.590-596
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• 2016

Biopsy is a typical needle type intervention procedure performed under radiographic image equipment such as computed tomography (CT) and cone-beam CT. This minimal invasive procedure is a simple and effective way for identifying cancerous condition of a suspicious tissue but radiation exposure for the patients and interventional radiologists is a critical problem. In order to overcome such trouble and improve accuracy in targeting of the needle, there have been various attempts using robot technology. Those devices and systems, however, are not for full procedure automation in biopsy without consideration for tissue sampling task. A robotic end-effector of a master-slave tele-operated needle type intervention robot system has been proposed to perform entire biopsy procedure by the authors. However, motorized sampling adopted in the device has different cutting speed from that of biopsy guns used in the conventional way. This paper presents the design of a novel robotic mechanism and protocol for the automation of biopsy procedure using spring-triggered biopsy gun mechanism. An experimental prototype has been successfully fabricated and shown its feasibility of the automated biopsy sequence.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.7
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• pp.623-629
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• 2013

This paper presents the implementation result of the EEG(electroencephalogram) signal transmission protocol and its test platform. EEG measured by a dry-type electrode is directly converted into digital signal by ADC(analog-to-digital converter). Thereafter it is transferred DSP(digital signal processor) platform by $I^2C$(inter-integrated circuit) protocol. DSP conducts the pre-processing of EEG and extracts feature vectors of EEG. In this work, we implement the $I^2C$ protocol with 16 channels by using 10 or 12-bit ADC. In the implementation results, the overhead ratio for the 4 bytes data burst transmission measures 2.16 and the total data rates are 345.6 kbps and 414.72 kbps with 10-bit and 12-bit 1 ksps ADC, respectively. Therefore, in order to support a high speed mode of $I^2C$ for 400 kbps, it is required to use 16:1 and $(8:1){\times}2$ ratios for slave:master in 10-bit ADC and 12-bit ADC, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.6
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• pp.1447-1453
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• 2014

Wireless Body Area Networks (WBAN), standardized as IEEE 802.15.6, enable digital devices on/around the human body to communicate with one another. WBAN is essentially a person's piconet consisting of a master (mobile) device and several slave devices, which follows his/her mobility pattern, and hence, occasionally collides with another piconet as people meet or pass by. As such, a mechanism to detect collision and avoid interference is needed for intra-piconet communications. In this paper, we focus on this notorious problem of piconet collision and propose Distributed Time Division Piconet Coexistence (DTDPC) using local time offset exchange as a simple, attractive solution. The proposed DTDPC provides different level of services for various applications. Besides our simulation results have shown that the proposed solution outperforms the conventional CSMA protocols.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.407-417
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• 2003

Enen though several GA-based optimization algorithms have been successfully applied to complex optimization problems in various engineering fields, GA-based optimization methods are computationally too expensive for practical use in the field of structural optimization, particularly for large- scale problems. Furthermore, a successful implementation of GA-based optimization algorithm requires a cumbersome and trial-and-error routine related to setting of parameters dependent on a optimization problem. Therefore, to overcome these disadvantages, a high-performance GA is developed in the form of distributed hybrid genetic algorithm for structural optimization on a cluster of personal computers. The distributed hybrid genetic algorithm proposed in this paper consist of a simple GA running on a master computer and multiple μ-GAs running on slave computers. The algorithm is implemented on a PC cluster and applied to the minimum weight design of steel structures. The results show that the computational time required for structural optimization process can be drastically reduced and the dependency on the parameters can be avoided.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.6
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• pp.515-522
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• 2017

In this paper, an isogeometric analysis for multipatch problem is investigated, in which two or more geometries are connected at the interface in a conforming or non-conforming conditions. To express higher continuity at the patch interface, two approaches such as Nitsche based method and master-slave method are formulated for the linear elasticity problem and discretized using the isogeometric approach using NURBS basis functions. A short comparison between two approaches in formulations reveals the pros and cons of them with the applicability in the isogeometric multipatch problem. In addition, a NURBS based stress recovery is adopted to express a better stress continuity through the post-processing. Numerical examples indicate the effectiveness of Nitsche method in the non-conforming patch, following the exact solution well. For the stress concentration problem with the conforming patch, introduced two methodologies show comparative results, meanwhile the NURBS based stress recovery presents an improved smooth stress contour in the whole domain including the patch interface.

• Journal of the Korean Society of Costume
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• v.63 no.6
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• pp.14-28
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• 2013

This study aims to identify the elements of black culture and use it to analyze the formative characteristics of casual fashion items as well as the symbolic meanings presented in the graphic designs of the items. First of all, in order to distinguish the identity of black culture, this study made a division into racial, social, and artistic aspects based on cultural specificities of Stuart Hall, a culture theorist. This was for a theoretical review and based on this review, a theoretical framework was developed to analyze the characteristics of American casual fashion design of black people. The case study selected 1719 fashion images of 137 male brands and 33 female brands from websites of companies manufacturing casual wear of black people in America. The following is a summary of the study results. The conceptual characteristics based on specificities of black culture can be categorized into ten attributes: playfulness in order to digest human grief and emotion positively, satire of the mainstream society, spontaneity through emotional expression from the heart, abstractness of various emotions elating suffering, humor trying to express negative aspects as the meaning of light and innocent laughter, dependence with passive attitudes toward discrimination and master-slave relationships in history, resistance against discrimination and disadvantages, African orientation and primitiveness pursuing natural conditions, aggressiveness against violence and unfair treatment, and confidence and defiance against social deprivation and corruption. Based on the results of an analysis through formative classification system founded on racial, social, and artistic aspects of black people, specificities of black culture are of formative characteristics of their casual fashion design. These elements are presented on graphic t-shirts through strong colors, loose silhouette, and details with many pockets. These characteristics were reflected in symbolic meanings presented in the graphic.

• Smart Structures and Systems
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• v.25 no.1
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• pp.1-22
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• 2020

The modal strain energy method is one of the efficient methods for detecting damage in the structures. Due to existing some limitations in real-world structures, sensors can only be located on a limited number of degrees of freedom (DOFs) of a structure. Therefore, the mode shape values in all DOFs of structures cannot be measured. In this paper, a modified modal strain energy based index (MMSEBI) is introduced to locate damaged elements of structures when a limited number of sensors are used. The proposed MMSEBI is based on the reconstruction of mode shapes using Improved Reduction System (IRS) method. Therefore, in the first step by employing IRS method, mode shapes in slave degrees of freedom are estimated by those of master degrees of freedom. In the second step, the proposed MMSEBI is used to located damage elements. In order to evaluate the efficiency of the proposed method, two numerical examples are considered under different damage patterns considering the measurement noise. Moreover, the universal threshold based on statistical hypothesis testing principles is applied to damage index values. The results show the effectiveness of the proposed MMSEBI for the structural damage localization when comparing with the available damage index named MESBI. The results demonstrate that the presented method can be used as a practical strategy for structural damage identification, especially when a limited number of sensors are installed on the structure. Finally, the combination of MMSEBI and IRS method can provide a reliable tool to identify the location of damage accurately.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.3
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• pp.626-637
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• 2014

On ship, especially on large ship, the flexure deformation between Master (M)/Slave (S) Inertial Navigation System (INS) is a key factor which determines the accuracy of the integrated system of M/S INS. In engineering this flexure deformation will be increased with the added ship size. In the M/S INS integrated system, the attitude error between MINS and SINS cannot really reflect the misalignment angle change of SINS due to the flexure deformation. At the same time, the flexure deformation will bring the change of the lever arm size, which further induces the uncertainty of lever arm velocity, resulting in the velocity matching error. To solve this problem, a $H_{\infty}$ algorithm is proposed, in which the attitude and velocity matching error caused by deformation is considered as measurement noise with limited energy, and measurement noise will be restrained by the robustness of $H_{\infty}$ filter. Based on the classical "attitude plus velocity" matching method, the progress of M/S INS information fusion is simulated and compared by using three kinds of schemes, which are known and unknown flexure deformation with standard Kalman filter, and unknown flexure deformation with $H_{\infty}$ filter, respectively. Simulation results indicate that $H_{\infty}$ filter can effectively improve the accuracy of information fusion when flexure deformation is unknown but non-ignorable.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1147-1158
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• 2006

Clustering algorithm is an essential element to implement a hierarchical routing protocol, especially for a large-scale wireless sensor network. In this paper, we propose a new type of energy-efficient clustering algorithm, which maximizes the physical distance between cluster head and gateway by a neighbor node discovery mechanism. Furthermore, a slave/master patching scheme is introduced as a useful means of further improving the energy-efficiency. It has been shown that the number of cluster heads can be reduced by as many as 21% as compared with the existing clustering algorithms.