• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.3
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• pp.139-147
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• 2017

In recent years, non-volatile memory express (NVMe), a new host controller interface standard, has been adapted to overcome performance bottlenecks caused by the acceleration of solid state drives (SSD). Recently, performance breakthrough cases over AHCI based SATA SSDs by adapting NVMe based PCI Express (PCIe) SSD to servers and PCs have been reported. Furthermore, replacing legacy eMMC-flash storage with NVMe based storage is also considered for next generation of mobile devices such as smartphones. The Linux kernel includes drivers for NVMe support, and as the kernel version increases, the implementation of the NVMe driver code has changed. However, mobile devices are often equipped with older versions of Android operating systems (OSes), where the newest features of NVMe drivers are not available. Therefore, different features of different NVMe driver implementations are not well evaluated on Android OSes. In this paper, we analyze the response time of the NVMe driver for various Linux kernel version.

• International Journal of Contents
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• v.8 no.4
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• pp.12-20
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• 2012

For a library to be able provide information services and fulfill its function as a knowledge convergence center capable of responding to various information demands, the development of next-generation information systems based on the latest information and communication technology is needed. The development of mobile information services using portable devices such smart phones and tablet PCs and information systems which incorporate the concepts of cloud computing, SaaS (Software as a Service), annotation and Library2.0 is also required. This paper describes a library information system that utilizes collective intelligence and cloud computing. The information system developed for this study adopts the SaaS-based cloud computing service concept to cope with the shift in the mobile service paradigm in libraries and the explosion of electronic data. The strengths of such a conceptual model include the sharing of resources, support of multi-tenants, and the configuration and support of metadata. The user services are provided in the form of software on-demand. To test the performance of the developed system, the efficiency analysis and TTA certification test were conducted. The results of performance tests, It is encouraging that, at least up to 100MB, the job time is approximately linear and with only a moderate overhead of less than one second. The system also passed the level-3 or higher criteria in the certification test, which includes the SaaS maturity, performance and application program functions.

• The KIPS Transactions:PartA
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• v.15A no.5
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• pp.249-258
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• 2008

DCDN(Distributed Contents Delivery Network) as known the next generation of CDN is to exploit the resource of client PCs based on P2P technology to provide low cost, high scalability and high speed services when contents are delivered. This DCDN has two problems. One is that DCDN can't provide a sustainable service because client PCs are on/off irregularly and their on times tend to focus on specific time zone, and the other is that client PCs can not be accessed outside in DCDN if they are behind NAT or Firewall. In this paper, we present a distributed contents delivery network based on home gateway for a sustainable service. If home gateway is used in DCDN instead of client PC, it can solve the two existing problems of DCDN. That is, home gateway can provide a sustainable service because it is on during all day and it is not behind NAT and Firewall. The proposed method is implemented with ASUS WL-500GP, a wired/wireless router. Experimental results show the effectiveness of the proposed method compared to the existing method of DCDN.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.703-710
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• 2017

Third-generation (3G) devicesare next-generation devices that allow the use of intelligent services and applications through the Internet of Things (IoT). As the market forexisting smart devices like smartphones and tablet PCs enters the stage of stagnation, the world is now focusing on 3G devices, parts, and services. This study is intended to measure the user's benefits from the various attributes of 3G devices by applying an economic valuation method. For this purpose, the conjoint analysis method was applied, which is one of the representative valuation methods. To apply conjoint analysis, the following attributes of 3G devicesare considered: mode of use, power efficiency, life care, and price. By applying the mixed logit model, the marginal willingness-to-pay(WTP) for each attribute was derived. The results are statistically significant. Respondents showed a high preference or complete flexibility in the mode of use attribute. And they were also found to have WTP for improvements in the life care attribute. The implications and quantitative results of this study are expected to be useful for policies and strategies in the 3G device market.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.8
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• pp.375-387
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• 2005

This paper presents an application of parallel Genetic Algorithm-Tabu Search (GA-TS) algorithm to search an optimal solution of a service restoration in distribution systems. The main objective of service restoration of distribution systems is, when a fault or overload occurs, to restore as much load as possible by transferring the do-energized load in the out of service area via network reconfiguration to the appropriate adjacent feeders at minimum operational cost without violating operating constraints, which is a combinatorial optimization problem. This problem has many constraints with many local minima to solve the optimal switch position. This paper develops parallel GA-TS algorithm for service restoration of distribution systems. In parallel GA-TS, GA operators are executed for each processor. To prevent solutions of low fitness from appearing in the next generation, strings below the average fitness are saved in the tabu list. If best fitness of the GA is not changed for several generations, TS operators are executed for the upper $10\%$ of the population to enhance the local searching capabilities. With migration operation, best string of each node is transferred to the neighboring node after predetermined iterations are executed. For parallel computing, we developed a PC cluster system consists of 8 PCs. Each PC employs the 2 GHz Pentium IV CPU and is connected with others through ethernet switch based fast ethernet. To show the validity of the proposed method, proposed algorithm has been tested with a practical distribution system in Korea. From the simulation results, we can find that the proposed algorithm is efficient for the distribution system service restoration in terms of the solution quality, speedup, efficiency and computation time.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.206-211
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• 2017

Recently computing devices by connecting to a network, grid computing, the next generation of digital neural networks that provide maximum service will connect all of the computer such as a PC or server, PDA into one giant network makes the virtual machine. Therefore, we propose the grid computing implementation model to be applied to meteorological business field as follows. First, grid computing will be used for tasks such as the development of numerical models below the mid-scale or test operations, and the final backup of the weather supercomputer. Second, the resources that will constitute grid computing are limited to business PCs and Linux servers operated by the central government considering operational efficiency. Third, the network is restricted to the LAN section, which suggests the implementation of high performance computing.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.10
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• pp.556-564
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• 2004

This paper presents an application of parallel Genetic Algorithm-Tabu Search(GA-TS) algorithm to search an optimal solution of a reconfiguration in distribution system. The aim of the reconfiguration of distribution systems is to determine switch position to be opened for loss minimization in the radial distribution systems, which is a discrete optimization problem. This problem has many constraints and very difficult to solve the optimal switch position because it has many local minima. This paper develops parallel GA-TS algorithm for reconfiguration of distribution systems. In parallel GA-TS, GA operators are executed for each processor. To prevent solution of low fitness from appearing in the next generation, strings below the average fitness are saved in the tabu list. If best fitness of the GA is not changed for several generations, TS operators are executed for the upper 10% of the population to enhance the local searching capabilities. With migration operation, best string of each node is transferred to the neighboring node aster predetermined iterations are executed. For parallel computing, we developed a PC-cluster system consisting of 8 PCs. Each PC employs the 2 GHz Pentium Ⅳ CPU and is connected with others through ethernet switch based fast ethernet. To show the usefulness of the proposed method, developed algorithm has been tested and compared on a distribution systems in the reference paper. From the simulation results, we can find that the proposed algorithm is efficient and robust for the reconfiguration of distribution system in terms of the solution qualify. speedup. efficiency and computation time.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.116-124
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• 2005

This paper presents an application of the parallel Genetic Algorithm-Tabu Search (GA- TS) algorithm, and that is to search for an optimal solution of a reconfiguration in distribution systems. The aim of the reconfiguration of distribution systems is to determine the appropriate switch position to be opened for loss minimization in radial distribution systems, which is a discrete optimization problem. This problem has many constraints and it is very difficult to solve the optimal switch position because of its numerous local minima. This paper develops a parallel GA- TS algorithm for the reconfiguration of distribution systems. In parallel GA-TS, GA operators are executed for each processor. To prevent solution of low fitness from appearing in the next generation, strings below the average fitness are saved in the tabu list. If best fitness of the GA is not changed for several generations, TS operators are executed for the upper 10$\%$ of the population to enhance the local searching capabilities. With migration operation, the best string of each node is transferred to the neighboring node after predetermined iterations are executed. For parallel computing, we developed a PC-cluster system consisting of 8 PCs. Each PC employs the 2 GHz Pentium IV CPU and is connected with others through switch based rapid Ethernet. To demonstrate the usefulness of the proposed method, the developed algorithm was tested and is compared to a distribution system in the reference paper From the simulation results, we can find that the proposed algorithm is efficient and robust for the reconfiguration of distribution system in terms of the solution quality, speedup, efficiency, and computation time.

• Journal of Radiation Protection and Research
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• v.37 no.1
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• pp.1-9
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• 2012

A year has passed since the nuclear power plant accident in Fukushima on March 11, 2011, and a survey for public perception on radiation by Korean people has been made. The methodological design was based on a quantitative survey and a frequency analysis was done. The analysis objects were survey papers (n=2,754pcs) answered by random ordinary citizens chosen from all over the country. The questionnaires, and study tool, were directly distributed and collected. A total of 40 questionnaires using a coefficient of Cronbach's ${\alpha}$ per each area was 'self perception of radiation' (0.620), 'radiation risk' (0.830), 'benefit from radiation' (0.781), 'radiation controlled' (0.685), 'informative source of radiation' (0.831), 'influence degree from Fukushima accident' (0.763), showing rather high score from all areas. As the result of the questionnaires, the knowledge of radiation concept was 69.50 out of 100 points, which shows a rather significant difference from the result of 'know well about radiation' (53.7%) and 'just know about radiation' (37.40%). According to the survey, one of the main reasons why radiation seems risky was that once exposed to radiation, it may not have negative impacts presently but, the next generation could see negative impacts (66.1%). About 41% of our respondents showed a negative position against the government's report on radiation while 39.5% of respondents said that we should stop running nuclear power in light of Fukushima nuclear power plant accident. This study was done for the first time by Korean people's public perception on radiation after the Fukushima nuclear power plant accident. We expect this might have significant contributions to the establishment of the government's policy on radiation.