• KDI Journal of Economic Policy
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• v.28 no.2
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• pp.97-129
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• 2006

This study investigates whether dynamic loan loss provisioning is necessary in Korean banking environments. Under the dynamic provisioning rule banks are required to accumulate additional reserves to general and specific provisionings in preparation for expected loan losses until maturity. This provisioning is most effective in the case that banks tend to recognize less loan losses in the business upturns and/or in the periods of increasing profits. The empirical study, however, shows that banks support procyclicality of loan loss privisioning and earning smoothing behavior over profit fluctuations. These findings suggest that Korea would not seriously need the introduction of dynamic loan loss provisioning. But this policy implication does not seem robust in view that the recent experience shows the countercyclicality of loan loss provisioning practices and negative correlation between earnings and provisioning after financial restructuring was completed. This result is partly attributable to vigorous shareholder activism because of high foreign ownership of most commercial banks. Once it is true that bank management is more interested in short-term performances, current loan loss provisioning would have attributes of impairing capital adequacy, hence strengthening loan loss provisiong requirements.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.404-408
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• 2006

This paper presents an anti-windup gain selection method for a complex vector synchronous frame PI current controller. The complex vector PI current controller is more robust to the parameter variation than the state feedback decoupling PI current controller. The complex vector PI current controller also includes an integral term, which can results in windup problem when the controller is saturated due to physical limitation of the system. Furthermore, even an anti-windup is utilized, inappropriate gain can deteriorate the performance of the current controller. Therefore, appropriate anti-windup gain selection method for a complex vector current controller has been proposed based on the mathematical description of the current control system. The superior performance of the current control system with the proposed anti-windup gain has been verified by the experimental results.

• Journal of Ecology and Environment
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• v.44 no.3
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• pp.115-125
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• 2020

Background: The phenomenon of tree dieback in forest ecosystems around the world, which is known to be associated with high temperatures that occur simultaneously with drought, has received much attention. Korea is experiencing a rapid rise in temperature relative to other regions. Particularly in the growth of evergreen conifers, temperature increases in winter and spring can have great influence. In recent years, there have been reports of group dieback of Pinus densiflora trees in Korea, and many studies are being conducted to identify the causes. However, research on techniques to diagnose and monitor drought stress in forest ecosystems on local and regional scales has been lacking. Results: In this study, we developed and evaluated an index to identify drought and high-temperature vulnerability in Pinus densiflora forests. We found the Drought Stress Index (DSI) that we developed to be effective in generally assessing the drought-reactive physiology of trees. During 2001-2016, in Korea, we refined the index and produced DSI data from a 1 × 1-km unit grid spanning the entire country. We found that the DSI data correlated with the event data of Pinus densiflora mass dieback compiled in this study. The average DSI value at times of occurrence of Pinus densiflora group dieback was 0.6, which was notably higher than during times of nonoccurrence. Conclusions: Our combination of the Standard Precipitation Index and growing degree days evolved and short- and long-term effects into a new index by which we found meaningful results using dieback event data. Topographical and biological factors and climate data should be considered to improve the DSI. This study serves as the first step in developing an even more robust index to monitor the vulnerability of forest ecosystems in Korea.

• Journal of KIISE
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• v.42 no.3
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• pp.320-327
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• 2015

Although service robots in various fields are being commercialized, most of them have problems that depend on explicit commands by users and have difficulty to generate robust reactions of the robot in the unstable condition using insufficient sensor data. To solve these problems, we modeled mirror neuron and theory of mind systems, and applied them to a robot agent to show the usefulness. In order to implement quick and intuitive response of the mirror neuron, the proposed intention-response model utilized behavior selection networks considering external stimuli and a goal, and in order to perform reactions based on the long-term action plan of theory of mind system, we planned behaviors of the sub-goal unit using a hierarchical task network planning, and controled behavior selection network modules. Experiments with various scenarios revealed that appropriate reactions were generated according to external stimuli.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.243.1-243.1
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• 2011

We demonstrate a facile and robust layer-by-layer (LbL) assembly method for the fabrication of nonvolatile resistive switching memory (NRSM) devices based on superparamagnetic nanocomposite multilayers, which allows the highly enhanced magnetic and resistive switching memory properties as well as the dense and homogeneous adsorption of nanoparticles, via nucleophilic substitution reaction (NSR) in nonpolar solvent. Superparamagnetic iron oxide nanoparticles (MP) of about size 12 nm (or 7 nm) synthesized with oleic acid (OA) in nonpolar solvent could be converted into 2-bromo-2-methylpropionic acid (BMPA)-stabilized iron oxide nanoparticles (BMPA-MP) by stabilizer exchange without change of solvent polarity. In addition, bromo groups of BMPA-MP could be connected with highly branched amine groups of poly (amidoamine) dendrimer (PAMA) in ethanol by NSR of between bromo and amine groups. Based on these results, nanocomposite multilayers using LbL assembly could be fabricated in nonpolar solvent by NSR of between BMPA-MP and PAMA without any additional phase transfer of MP for conventional LbL assembly. These resulting superparamagnetic multilayers displayed highly improved magnetic and resistive switching memory properties in comparison with those of multilayers based on water-dispersible MP. Furthermore, NRSM devices, which were fabricated by LbL assembly method under atmospheric conditions, exhibited the outstanding performances such as long-term stability, fast switching speed and high ON/OFF ratio comparable to that of conventional inorganic NRSM devices produced by vacuum deposition.

• Computers and Concrete
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• v.8 no.3
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• pp.293-309
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• 2011

A long-term structural health monitoring (SHM) system comprising over 700 sensors of sixteen types has been implemented on the Guangzhou Television and Sightseeing Tower (GTST) of 610 m high for real-time monitoring of the structure at both construction and service stages. As part of this sophisticated SHM system, 48 temperature sensors have been deployed at 12 cross-sections of the reinforced concrete inner structure of the GTST to provide on-line monitoring via a wireless data transmission system. In this paper, the differential temperature profiles in the reinforced concrete inner structure of the GTST, which are mainly caused by solar radiation, are recognized from the monitoring data with the purpose of understanding the temperature-induced structural internal forces and deformations. After a careful examination of the pre-classified temperature measurement data obtained under sunny days and non-sunny days, common characteristic of the daily temperature variation is observed from the data acquired in sunny days. Making use of 60-day temperature measurement data obtained in sunny days, statistical patterns of the daily rising temperature and daily descending temperature are synthesized, and temperature distribution models of the reinforced concrete inner structure of the GTST are formulated using linear regression analysis. The developed monitoring-based temperature distribution models will serve as a reliable input for numerical prediction of the temperature-induced deformations and provide a robust basis to facilitate the design and construction of similar structures in consideration of thermal effects.

• Journal of the Korea Society of Computer and Information
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• v.25 no.7
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• pp.57-64
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• 2020

In this paper, we propose an scalable re-detection for correlation filter in visual tracking. In real world, there are lots of target disappearances and reappearances during tracking, thus failure detection and re-detection methods are needed. One of the important point for re-detection is that a searching area must be large enough to find the missing target. For robust visual tracking, we adopt kernelized correlation filter as a baseline. Correlation filters have been extensively studied for visual object tracking in recent years. However conventional correlation filters detect the target in the same size area with the trained filter which is only 2 to 3 times larger than the target. When the target is disappeared for a long time, we need to search a wide area to re-detect the target. Proposed algorithm can search the target in a scalable area, hence the searching area is expanded by 2% in every frame from the target loss. Four datasets are used for experiments and both qualitative and quantitative results are shown in this paper. Our algorithm succeed the target re-detection in challenging datasets while conventional correlation filter fails.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.371-378
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• 2002

In the resent years, the term mobile agent is probably one of the most overused words in many appliable areas of distributed open systems as electronic commerce and electronic data interchange, and it has very different meanings in the area of artificial intelligence, network management, or distributed systems. However, the use of mobile agent adds significant problems, primarily in the area of EC/EDI. Therefore it is very important to control the roaming agents to keep one's privacy or property in distributed open networks. The surge in secure intranets for commercial applications provides a robust, secure environment to which trading partners can increasingly entrust their interactions to some mobile agents. In this paper, we introduce a mechanism to protect mobile agent itself from the malicious server he is visiting and also we introduce a mechanism to protect vital resources of the open systems as internet.

• Journal of Communications and Networks
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• v.11 no.6
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• pp.544-555
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• 2009

This work continues a trend of developments aimed at exploiting the physical layer of the open systems interconnection (OSI) model to enhance wireless network security. The goal is to augment activity occurring across other OSI layers and provide improved safeguards against unauthorized access. Relative to intrusion detection and anti-spoofing, this paper provides details for a proof-of-concept investigation involving "air monitor" applications where physical equipment constraints are not overly restrictive. In this case, RF fingerprinting is emerging as a viable security measure for providing device-specific identification (manufacturer, model, and/or serial number). RF fingerprint features can be extracted from various regions of collected bursts, the detection of which has been extensively researched. Given reliable burst detection, the near-term challenge is to find robust fingerprint features to improve device distinguishability. This is addressed here using wavelet domain (WD) RF fingerprinting based on dual-tree complex wavelet transform (DT-$\mathbb{C}WT$) features extracted from the non-transient preamble response of OFDM-based 802.11a signals. Intra-manufacturer classification performance is evaluated using four like-model Cisco devices with dissimilar serial numbers. WD fingerprinting effectiveness is demonstrated using Fisher-based multiple discriminant analysis (MDA) with maximum likelihood (ML) classification. The effects of varying channel SNR, burst detection error and dissimilar SNRs for MDA/ML training and classification are considered. Relative to time domain (TD) RF fingerprinting, WD fingerprinting with DT-$\mathbb{C}WT$ features emerged as the superior alternative for all scenarios at SNRs below 20 dB while achieving performance gains of up to 8 dB at 80% classification accuracy.

• STI Policy Review
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• v.1 no.3
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• pp.25-37
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• 2010

Advances in Information Communication Technologies (ICT) have demonstrated tremendous potential for solving development challenges and improving development processes, culminating in the new Development 2.0. Many development practitioners have embraced ICT (particularly on Web 2.0 and mobile phone technologies and applications), which have become hot topics in both the development community and the policy community as they engage in development practice and dialogue. Despite this excitement, there lacks among the policy community a robust understanding of the powers and pitfalls of ICT in development, executed actions to back the excited chatter, and dissemination of this understanding to practitioners and policymakers alike. We conducted a literature review, interviewed experts, and engaged in discussion with leaders in international development and science and technology policy to provide an operational framework base in which to view ICT in development. This framework regards ICT as tools that support more effective and efficient community development actions and appropriate consideration of general guidelines, which enable better engagement across and within sectors and individuals. Flexibility and accountability are critical requirements pervading throughout the various actions and guidelines, which promote transparent, partnership-based, and sustainable development. We highlight the strengths and weaknesses of ICT to focus on the cautions to keep ICT access and distribution in context, understand the various levels of technologies and services, and dig below the surface as excitement about ICT increases and threatens to become a short-term solution. We offer ideas for specific programs that policymakers can implement to contribute to a more efficient and effective development process to ultimately support global human development, but stress the endless possibilities that can be explored with creativity and flexibility beyond what is proposed here.