• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.110-132
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• 2019

To ensure reliable and secure communication in heterogeneous cellular network (HCN) with imperfect channel state information (CSI), we proposed a coordinated multipoint (CoMP) transmission scheme based on dual-threshold optimization, in which only base stations (BSs) with good channel conditions are selected for transmission. First, we present a candidate BSs formation policy to increase access efficiency, which provides a candidate region of serving BSs. Then, we design a CoMP networking strategy to select serving BSs from the set of candidate BSs, which degrades the influence of channel estimation errors and guarantees qualities of communication links. Finally, we analyze the performance of the proposed scheme, and present a dual-threshold optimization model to further support the performance. Numerical results are presented to verify our theoretical analysis, which draw a conclusion that the CoMP transmission scheme can ensure reliable and secure communication in dense HCNs with imperfect CSI.

• Asia pacific journal of information systems
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• v.10 no.2
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• pp.97-123
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• 2000

This paper proposes a model for assessing enterprise network maturity. We define maturity in terms of the institutional and member support for the network(organizational maturity) and its technical sophistication(technological maturity), and examine their relationships. We build several hypotheses about the relationships between the maturity types and between the maturity of the network and various organizational factors including industry, size, and performance of the enterprise. We test the hypotheses using data collected from a questionnaire survey with Korean firms. The results show that there is a positive correlation between organizational and technological maturity. It is also found that investment in the network infrastructure has a positive influence on the organizational efficiency. However, it is found that industry type does not affect network utilization, but size does, suggesting that large firms utilize network infrastructure more than small ones do. We also identify various relationships among performance, satisfaction level and the maturity of the enterprise networks. Finally, we provide an overview on the current technological state of the Korean enterprise networks.

• Journal of Energy Engineering
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• v.18 no.2
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• pp.75-86
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• 2009

This paper studies examines the R&D efficiency in Korean energy industry by making multiple logistic regression of the product technological level with firms' endogenous technological efforts and cooperations for R&D between upstream and downstream firms. The technological level of Korean energy industry is analyzed to have been positively influenced by economy of scale effect and cooperations for R&D between upstream and downstream firms, but negatively impacted by firm size, and not impacted by competitive market structure, R&D investment, and R&D manpowers. The implications of this study are as follows: i) to heighten the technological level, domestic market would be transformed to be more competitive; ii) Korean Energy industry should make efforts intensifying R&D-related manpowers and investments; iii) although the firm size is analyzed to have negative impact on technological level, firms, lager or smaller, must be supported to accumulate technological capabilities; iv) R&D-cooperating efforts between upstream and downstream firms on the value-chain should be supported.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.4
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• pp.358-365
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• 2014

The purpose of this paper is to analyze the efficiency of government investment in the deployment and technological development of three technological areas - wind power, photovoltaic and fuel cell - of renewable energy in Korea using the DEA (data envelopment analysis). The efficiencies of government investment in renewable energies are measured and compared among three kinds of technologies using the actual data during 2007~2009. In the present DEA model, R&D investment and government subsidies for renewable energy usage promotion are selected as input variables, and the number of patents, supply level, and the production cost as output variable. As a result, it is found that the wind power is the most efficient renewable energy in Korea in the perspective of the efficiency of government investment.

• Journal of Korean Society for Quality Management
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• v.49 no.4
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• pp.641-654
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• 2021

Purpose: One distinctive trend in the recent industrial and technological development has been the change in the structures of industries brought by information technology, boosting the productivity of different sectors. This relation has clearly opened a path for the fourth industrial revolution to reform numerous industrial sectors, including i-fashion sectors. Therefore, in this research, we would like to present the direction of the direction policy for the fusion of the manufacturing industry and the service industry of i-fashion. Methods: In this study, an empirical time series data analysis of machinery investment efficiency and capital investment efficiency of 43 industrial sectors in manufacturing and service was conducted to show their potential and ongoing convergence toward i-fashion. Results: Most impressive as a finding in this research was that those sectors previously underinvested due to a combination of technological and financial reasons found an exit for growth. In textile and apparel sectors, that could be the i-fashion. Conclusion: One strong implication of this study is that sectoral level convergence based on technology and industry is occurring, and i-fashion is one of the industrial convergence case to be observed.

• Korea Trade Review
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• v.42 no.5
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• pp.137-159
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• 2017

This study divides manufacturing in 18 countries including Korea, China, Japan and OECD countries into 11 areas and estimates and compares the technological efficiency of each industry. The traditional view of productivity is to increase production capacity through technological innovation or process innovation, but it is also influenced by the technological efficiency of production process. A Stochastic Frontier Production Model (SFM) is a representative method for estimating the technical efficiency of such production. First, as a result of estimating the production function by setting the output variable as total output or value-added, in both cases, the output increased significantly in all manufacturing sectors as inputs of labor, capital, and intermediate increased. On the other hand, R&D investment has a large impact on output in chemical, electronics, and machinery industries. Next, as a result of estimating the technological efficiency through the production function, when the total output is set as the output variable, the overall average of each sector is 0.8 or more, showing mostly high efficiency. However, when value-added was set, Japan had the highest level in most manufacturing sectors, while other countries were lower than the efficiency of the total output. Comparing the three countries of Korea, China and Japan, Japan showed the highest efficiency in most manufacturing sectors, and Korea was about half or one third of Japan and China was lower than Korea. However, in the food and electronics sectors, China is higher than Korea, indicating that China's production efficiency has greatly improved. As such, Korea is not able to narrow its gap with Japan relatively faster than China's rapid growth. Therefore, various policy supports are needed to promote technology development. In addition, in order to improve manufacturing productivity, it is necessary to shift to an economic structure that can raise technological efficiency as well as technology development.

• Journal of Power Electronics
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• v.12 no.5
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• pp.758-768
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• 2012

This paper presents the modeling and position-sensorless vector control of a dual-airgap axial flux permanent magnet (AFPM) machine optimized for use in flywheel energy storage system (FESS) applications. The proposed AFPM machine has two sets of three-phase stator windings but requires only a single power converter to control both the electromagnetic torque and the axial levitation force. The proper controllability of the latter is crucial as it can be utilized to minimize the vertical bearing stress to improve the efficiency of the FESS. The method for controlling both the speed and axial displacement of the machine is discussed. An inherent speed sensorless observer is also proposed for speed estimation. The proposed observer eliminates the rotary encoder, which in turn reduces the overall weight and cost of the system while improving its reliability. The effectiveness of the proposed control scheme has been verified by simulations and experiments on a prototype machine.

• Journal of Distribution Science
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• v.19 no.3
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• pp.15-23
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• 2021

Purpose: This study aims to identify the role of technological progress in the distribution sector in Saudi Arabia. Research design, data, and methodology: The study applies the Autoregressive Distributed Lag (ARDL) approach to estimate the Cobb Douglas production function of the wholesale and retail trade sector in Saudi Arabia, relied on annual data from the General Authority for Statistics from 2005 to 2019. Results: The results show that there is a long run relationship between the production of the wholesale and retail trade sector in KSA and the factors of production labour, capital and technology progress. The elasticity of the wholesale and retail trade production with respect to capital and labour are 0.26 and 0.78 respectively; the coefficients are positive and statistically significant. The wholesale and retail trade sector is operating under increasing returns to scale. The main result indicates that the elasticity of the wholesale and retail production with respect to the technology progress is 4.62%, which is positive and statistically significant. Conclusions: The study concluded that technological progress has a positive contribution to the growth of the distribution sector in KSA. Therefore, the technological progress can improve the productivity and efficiency of the resources allocated to the dis.

• The Journal of the Korea Contents Association
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• v.21 no.11
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• pp.361-374
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• 2021

The purpose of this study is to analyze the efficiency and productivity of technological innovation activities of companies certified as innovative pharmaceutical companies by the government to diagnose their competitiveness and derive measures to strengthen them. This study collected pharmaceutical input (R&D expenditures and number of employees) and output (sale, operating profit and patent) data between 2017 and 2019 for 38 innovative pharmaceutical companies. This study analyzed them using the data envelopment analysis (DEA) method, Tobit model and the Malmquist Productivity Index (MPI). First, the DEA result of the innovative pharmaceutical companies show that between the value of the CCR model of the scale efficiency and the value of the BCC model to diagnose the internal operation efficiency is differences. Second, efficiency does not differ between corporate characteristics. Third, Tobit model shows that number of patents held have positive effects on efficiency. Forth, overall MPI is 0.89. This can be interpreted as the rate of TECI decreased 3%p and TCI has increased 4%p. The results of this study can be used as decision-making data for response strategies to improve efficiency by identifying the cause of inefficiency and presenting target values.

• International journal of advanced smart convergence
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• v.4 no.1
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• pp.162-178
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• 2015

Petroleum based fossil fuels used to power most processes today are non-renewable fuels. This means that once used, they cannot be reproduced for a very long time. The maximum combustion of fossil fuels occurs in automobiles i.e. the vehicles we drive every day. Thus, there is a requirement to shift from these non-renenewable sources of energy to sources that are renewable and environment friendly. This is causing the need to shift towards more environmentally-sustainable transport fuels, preferably derived from biomass, such as biodiesel blends. These blends can be made from oils that are available in abundance or as waste e.g. waste cooking oil, animal fat, oil from seeds, oil from algae etc. Waste Cooking Oil(WCO) is a waste product and so, converting it into a transportation fuel is considered highly environmentally sustainable. Keeping this in mind, a life cycle assessment (LCA) was performed to evaluate the environmental implications of replacing diesel fuel with WCO biodiesel blends in a regular Diesel engine. This study uses Life Cycle Assessment (LCA) to determine the environmental outcomes of biodiesel from WCO in terms of global warming potential, life cycle energy efficiency (LCEE) and fossil energy ratio (FER) using the life cycle inventory and the openLCA software, version 1.3.4: 2007 - 2013 GreenDelta. This study resulted in the conclusion that the biodiesel production process from WCO in particular is more environmentally sustainable as compared to the preparation of diesel from raw oil, also taking into account the combustion products that are released into the atmosphere as exhaust emissions.