• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4354-4358
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• 2011

Many Korean construction companies have fallen on hard times because the construction business continues to stagnate. Therefore it is necessary to measure the management efficiency for efficient operation and strengthening competitiveness of them in order to survive a difficult situation. This paper proposes a combined ANP and DEA model to analyze the efficiency of the listed construction firms. In order to determine the input and output variables of DEA, the ANP model is applied to evaluate the importance of input and output variables. The benchmarking companies and efficiency value for the construction firms with inefficiency are also provided to improve the their efficiency. The 57 listed construction companies consisted of 36 listed on KOSPI and 21 listed on KOSDAQ are analyzed in this study. The analysis results show that 11 companies whose values of CCR are 1, and 14 firms whose values of BCC efficiency are 1. In additions, the 19 firms have the scalability efficiency. Finally, we test the correlation between efficiency and the stock price.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.4
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• pp.362-372
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• 2000

The causal message logging is a low-cost technique of building a distributed system that can tolerate process crash failures. Previous research in causal message logging protocol assumes that the number of processes in a fault-tolerant system is fixed. This assumption makes all processes modify their data structures when a new process is added or an existing process terminates. However, the proposed approach in this paper allows to each process retain identifiers of only the communicating processes instead of all processes. This mechanism enables the fault-tolerant system to operate at many different scales. Using this mechanism, we develop a new algorithm that can be adapted for recovery in existing causal message logging protocols. Our recovery algorithm is 1) a distributed technique which does not require recovery leader, 2) a nonblocking protocol which does not force live processes to block while recovery is in progress, and 3) a novel mechanism which can tolerate failures of an arbitrary number of processes. Earlier causal message logging protocols lack one or more of the above properties.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.86-92
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• 2011

In this paper, we propose a novel hardware MPI(Message Passing Interface) unit which supports message passing in multiprocessor system which use distributed memory architecture. MPI Hardware unit processes data synchronization, transmission and completion, and it supports processor non-blocking operation so it reduces overhead according to synchronization. Additionally, MPI hardware unit combines ready entry, request entry, reserve entry which save and manage the synchronized messages and performs the multiple outstanding issue and out of order completion. According to BFM(Bus Functional Model) simulation result, the performance is increased by 25% on many to many communication. After we designed MPI unit using HDL, with synopsys design compiler we synthesized, and for synthesis library we used MagnaChip $0.18{\mu}m$. And then we making prototype chip. The proposed message transmission interface hardware shows high performance for its increase in size. Thus, as we consider low-cost design and scalability, MPI hardware unit is useful in increasing overall performance of embedded MPSoC(Multi-Processor System-on-Chip).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1933-1941
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• 2016

This paper compares the performance of wireless communication technologies to replace the wired networks by wireless networks on avionics intra-communication. Due to the drawbacks of wired network, such as complexity, weight, maintenance cost and scalability, it leads to the high data rate and network traffic demands of avionics systems. Therefore, in WAIC(Wireless Avionics Intra-Communications) system suggested by ITU(International Telecommunication Union), based on environment of avionics system and requirements of a wired network, wireless network structures are defined to solve the problems of wired networks. In this paper, we consider features, advantages and disadvantages of wireless communication technologies which can be used for wireless avionics network, and we propose suitable wireless communication technology candidates for wireless avionics networks in WAIC environments.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.7
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• pp.440-447
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• 2006

Grid computing is the complex deployments of various hardware and software components. The Grid environment should provide a mechanism for real-time monitoring and notification. It is very important to implement a monitoring mechanism in the Grid environment. Most existing monitoring systems only focus on their own requirements. With the development of Grid computing technology, the extensible monitoring systems become more and more feasible and popular. In this paper, we describe our research and development works on M-Mon, a novel framework for the flexible and adaptive Grid monitoring system. M-Mon system focuses on some critical issues like scalability, reusability, runtime extensibility, protocol transparency and uniform data representation. To provide interoperability with other monitoring systems and to reuse legacy facilities with a minimum effort, our monitoring system has been developed using service-oriented architecture.

• Journal of Information Technology Services
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• v.16 no.4
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• pp.33-46
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• 2017

Increasing popularity of smartphone is creating many changes in payment market sector also. The new fin-tech and simple mobile payment service have provided convenience as well as various benefits and value-added services to create new payment culture. However, the infrastructure of offline shops is too poor for users to use the simple mobile payment services in Korea. There are several reasons why the support of simple mobile payment services by offline shops has reached the limit in Korea. They include the reluctance of shop owners due to highly priced devices, the failure of NFC of the leading offline payment infrastructure to support iOS, the services that are biased to the specific manufacturers and smartphones (Samsung Pay and LG Pay), prefer large shops (SSG Pay and L PAY), and focus on online transactions. This study used the Bluetooth technology that is the standard feature built in all smartphone to expand the offline shops that accept the simple mobile payment services ensuring universality and scalability from the convenience of customer's and service provider's aspects. Applying the same payment scene as the existing NFC payment method from the user's aspect and the Bluetooth technology from the service provider's aspect enables support of all smartphones and offering value-added services such as electronic receipt and promotions through the large-capacity bidirectional data transfer. This study is intended to review the simple mobile payment services in Korea and other countries, propose the simple mobile payment service model for Korea by analyzing the Bluetooth technology and preceding studies of payment services using BLE technology, and develop the pilot system using the BLE technology to verify the proposed system with actual shops.

• Journal of Internet Computing and Services
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• v.16 no.2
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• pp.7-17
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• 2015

To provide scalability, wireless sensor network has cluster-based architecture. Wireless sensor network can be implemented based on the IEEE 802.15.4 which is exploited in 2.4GHz ISM frequency band. Since this frequency band is used for various data communication, network status of wireless sensor networks frequently changes according to wireless environment. Thus, wireless channel selection to avoid reduction of transmission efficiency is required. This paper estimates network status using the information that a cluster-head collects in a cluster. Through objective function with throughput, RSSI level and reliability as input parameters, this paper proposes proper wireless channel selection. Simulation results show that the proposed method maintains transmission efficiency even though network status changes.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.99-107
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• 2010

SNMP(Simple Network Management Protocol) is most commonly used as a standard protocol for effective network management by supporting the increasing size of the network and the variety of network elements such as router, switch, server and so on. However, SNMP has performance drawbacks of network overhead, processing latency, and the inefficiency in data retrieval. In this paper, we propose two schemes to improve the performance of SNMP; 1) the first scheme to reduce the amount of redundant OID information within a SNMP-GetBulk response message, 2) the second scheme of newly proposed SNMP-GetUpdate message combined with the cache in MNS. Through the analysis with real experiments, we show that our first scheme reduces the network overhead and the second scheme improves the processing latency and the retrieval of SNMP MB tables. And, therefore the scalability of network management can be improved.

• Journal of KIISE:Information Networking
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• v.30 no.2
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• pp.143-154
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• 2003

There is a growing trend in developing system for distributed mobile system that supports services - job flow management, video conference, replicated data management and resource allocation. Supporting these services, applications have to use causally ordered message delivery. Previous proposals that provide causally ordered message delivery have problems such as communication overhead, message delaying, scalability, computing overload of mobile host. In this paper, we proposed efficient protocol for causally ordered message delivery using the methods that MSS maintains dependency information matrix between MSS and MH, Piggybacking dependency information about each immediate predecessor message. Proposed algorithm, when compared with previous proposals, provides a low message overhead, and low probability of unnecessary inhibition in delivering messages. Also, it consider resource restriction of MH and low bandwidth of wireless communication by computing most of algorithm at MSS, and reduce processing delay by executing causally ordered message delivery a unit of MH.

• Journal of The Korean Astronomical Society
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• v.47 no.2
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• pp.43-47
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• 2014

Many advanced ground-based solar telescopes improve the spatial resolution of observation images using an adaptive optics (AO) system. As any AO correction remains only partial, it is necessary to use post-processing image reconstruction techniques such as speckle masking or shift-and-add (SAA) to reconstruct a high-spatial-resolution image from atmospherically degraded solar images. In the New Vacuum Solar Telescope (NVST), the spatial resolution in solar images is improved by frame selection and SAA. In order to overcome the burden of massive speckle data processing, we investigate the possibility of using the speckle reconstruction program in a real-time application at the telescope site. The code has been written in the C programming language and optimized for parallel processing in a multi-processor environment. We analyze the scalability of the code to identify possible bottlenecks, and we conclude that the presented code is capable of being run in real-time reconstruction applications at NVST and future large aperture solar telescopes if care is taken that the multi-processor environment has low latencies between the computation nodes.