• Health Policy and Management
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• v.9 no.4
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• pp.87-119
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• 1999

The main purpose of this research is to measure and analyze how productive the health centers are and how much inputs(or outputs) in the inefficient health centers should be decreased(or increased) for efficiency. The evaluation of the performance of health centers gives a strong incentive to improve resource allocation in regional health planning. It has been, however, implemented very rarely until now. In this regard, this paper measures the performance of the health centers with a single indicator for multiple-outputs in terms of productivity(technical efficiency), based on Data Envelopment method. The 20 Kyungnam health centers which provide clinic services and specific primary health care services were analyzed. The results show that 50.0% of 20 health centers were productive with respective to overall technical efficiency, 65.0% were productive for pure technical efficiency, and 50.0% for scale efficiency. The inefficient group includes Geoje, Mahsan, Miryang, Sahchun, Tongyoung, Gosung, Nahmhae, Euryang, Hahmahn, Hahbchun health centers. The worst case was identified as Tongyoung health center which represented a 47.5% efficiency, compared with productive health centers. The empirical results for input-output analysis indicates that the low-productive health centers have excessive manpower in administration department, producing low outputs in clinical services and vaccination program. These findings imply that a systemic evaluation of the performance of the Korean health centers and the subsequent structural reform are strongly required.

• Current Optics and Photonics
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• v.1 no.4
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• pp.315-324
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• 2017

In recent years, multicast services such as high-definition television (HDTV), video conferencing, interactive distance learning, and distributed games have increased exponentially, and wavelength-division multiplexing (WDM) networks are considered to be a promising technology due to their support for multicast applications. Multicast survivability in WDM networks has been the focus of extensive attention since a single-link failure in an optical network may result in a massive loss of data. But the improvement of network survivability increases energy consumption due to more resource allocation for protection. In this paper, an energy-efficient multicast algorithm (EEMA) is proposed to reduce energy consumption in WDM networks. Two cost functions are defined based on the link state to determine both working and protection paths for a multicast request in WDM networks. To increase the number of sleeping links, the link cost function of the working path aims to integrate new working path into the links with more working paths. Sleeping links indicate the links in sleep mode, which do not have any working path. To increase bandwidth utilization by sharing spare capacity, the cost function of the protection path is defined to use sleeping fibers for establishing new protection paths. Finally, the performance of the proposed algorithm is evaluated in terms of energy consumption, and also the blocking probability is evaluated under various traffic environments through OPNET. Simulation results show that our algorithm reduces energy consumption while maintaining the quality of service.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.65-70
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• 2013

In this paper, we propose a multi-hop cooperative transmission protocol to obtain energy savings in static wireless networks. Each terminal in the network is equipped with a single antenna and each receiver uses equal gain combining technique (EGC) to combine received signals. We also propose a power allocation strategy which optimizes the total transmit power at each stage. Monte-Carlo simulations are presented to evaluate and compare performance of the proposed protocol with the multi-hop direct transmission (MDT) and the cooperative routing protocol proposed by Khadani [8], in terms of the average total transmit power and the average number of required stages.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1501-1505
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• 2004

The authentication system of high-speed internet in IP-infra is not warm enough to administration of systematic authentication information for user's legalization, connection right and resources allocation in order to both methods of authentication-unauthentication connection system according to transmission method . Also unauthentication connection raises a difficulty condition to user's needs satisfaction in order to a load weighting of system and network and a drop of transmission speed. Accordingly, this study brings forth authentication system construction in a high-speed IP infrastructure using spam sever able to construct the suitable network condition according to unifying authentication-unauthentication system for single authentication system.

• ETRI Journal
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• v.28 no.3
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• pp.282-290
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• 2006

In vertically overlaid cellular systems, a temporary traffic concentration can occur in a hot-spot area, and this adversely affects overall system capacity. In this paper, we develop an adaptive hot-spot operating scheme (AHOS) to mitigate the negative effects from the nonuniform distribution of user location and the variation in the mixture of QoS requirements in orthogonal frequency division multiple access downlink systems. Here, the base station in a macrocell can control the operation of picocells within the cell, and turns them on or off according to the system overload estimation function. In order to determine whether the set of picocells is turned on or off, we define an AHOS gain index that describes the number of subcarriers saved to the macrocell by turning a specific picocell on. For initiating the picocell OFF procedure, we utilize the changes in traffic concentration and co-channel interference to the neighboring cells. According to computer simulation, the AHOS has been proved to have maximize system throughput while maintaining a very low QoS outage probability under various system scenarios in both a single-cell and multi-cell environments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.5
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• pp.8-15
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• 2011

LTE-Advanced aims at peak data rates of 1Gbits/s for the downlink and 500 Mbits/s for the uplink, which can be accomplished only by using wide spectrum allocation of 100MHz as well as advanced multiple input multiple output antenna techniques to the uplink. This paper analyzes the uplink precoding techniques which include LTE codebook of downlink, singular value decomposition codebook, and equal gain transmission codebook over LTE defined single carrier frequency division multiplexing systems. Finally considering nonlinear transmit power amplifier model, it is shown that link-level performance of EGT is superior to those of any other precoding schemes.

• Information Systems Review
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• v.3 no.1
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• pp.3-18
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• 2001

The Internet is taking up every single life of us with a huge speed of growth. If the ideal market called 'perfect competition' in economics will ever come true in this digital world, the sellers won't be able to have monopolistic profits above the marginal cost any more, letting the resource allocation much more efficient. This paper attempts to test whether this theory is true in e-market as well through observing price differences between online and offline retailers of extremely homogeneous products, CDs. Since most results from previous research were supporting the inefficiency of e-market in price level, price adjustment, and especially price dispersion, this article designed the research methodology most carefully. The results of pervious works are partly due to the immaturity of the Internet market or due to the uniqueness of the American CD market, where oligopolistic market players are significantly dominant. The analysis of price data of 20 titles from 20 retailers for five weeks supports that online market is more efficient than offline market with statistical significance in all the three dimensions. We could conclude that the e-market is going much more efficient at least compared to the offline market and the more would it be unless the sellers resist and prevent comparison-shopping.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.9
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• pp.3034-3055
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• 2014

Wireless Sensor Networks have extensively been utilized for ambient data collection from simple linear structures to dense tiered deployments. Issues related to optimal resource allocation still persist for simplistic deployments including linear and hierarchical networks. In this work, we investigate the case of dimensioning parameters for linear and tiered wireless sensor network deployments with notion of providing extended lifetime and reliable data delivery over extensive infrastructures. We provide a single consolidated reference for selection of intrinsic sensor network parameters like number of required nodes for deployment over specified area, network operational lifetime, data aggregation requirements, energy dissipation concerns and communication channel related signal reliability. The dimensioning parameters have been analyzed in a pipeline monitoring scenario using ZigBee communication platform and subsequently referred with analytical models to ensure the dimensioning process is reflected in real world deployment with minimum resource consumption and best network connectivity. Concerns over data aggregation and routing delay minimization have been discussed with possible solutions. Finally, we propose a node placement strategy based on a dynamic programming model for achieving reliable received signals and consistent application in structural health monitoring with multi hop and long distance connectivity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.416-421
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• 2007

ZigBee is becoming a promising communication protocol for wireless sensor networks based on low-power consumption. In case of a ZigBee network requesting continuous transmission of sensed data, the required bandwidth can be overwhelm the maximum transmission rate of 150Kbps. However, the ZigBee router which delivers data from source node to destination node can transmit data at most in a half of maximum rate because the router can not send and receive the data simultaneously. In this paper, we propose and implement a dual-channel router which can send and receive data simultaneously. Also, we propose a centralized channel allocation algorithm to allocate different channels to each module. The experiment result by the proposed dual-channel router shows a maximum throughput of 150Kbps as large as twice of normal single-channel router.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1583-1598
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• 2019

Recently, software has increased in complexity and been applied in various industrial fields. As a result, the presence of software bugs cannot be avoided. Various bug severity prediction methodologies have been proposed, but their performance needs to be further improved. In this study, we propose a novel technique for bug severity prediction in cross projects such as Eclipse, Mozilla, WireShark, and Xamarin by using topic modeling and similarity (i.e., KL-divergence). First, we construct topic models from bug repositories in cross projects using Latent Dirichlet Allocation (LDA). Then, we find topics in each project that contain the most numerous similar bug reports by using a new bug report. Next, we extract the bug reports belonging to the selected topics and input them to a Naïve Bayes Multinomial (NBM) algorithm. Finally, we predict the bug severity in the new bug report. In order to evaluate the performance of our approach and to verify the difference between cross projects and single project, we compare it with the Naïve Bayes Multinomial approach; the Lamkanfi methodology, which is a well-known bug severity prediction approach; and an emotional similarity-based bug severity prediction approach. Our approach exhibits a better performance than the compared methods.