• Proceedings of the Korea Inteligent Information System Society Conference
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• 1999.10a
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• pp.281-289
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• 1999

The objective of this paper is to propose a brand new interface mechanism to provide more intelligent decision making support for EC problems. Its main virtue is based on a numerical process mechanism by using an Extended AND-OR Graph (EAOG)-based logic algebra. Using this mechanism, decision makers engaged in electronic commerce (EC) can effectively deal with complicated decision making problems. In the field of traditional expert systems research, AND-OR Graph approach has been suggested as a useful tool for representing the logic flowchart of the forward and/or backward chaining inference methods. However, the AND-OR Graph approach cannot be effectively used in the EC problems in which real-time problem-solving property should be highly required. In this sense, we propose the EAOG inference mechanism for EC problem-solving in which heurisric knowledge necessary for intelligent EC problem-solving can be represented in a form of matrix. Finally, we have proved the validity of our approach with several propositions and an illustrative EC example

• ETRI Journal
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• v.34 no.5
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• pp.684-689
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• 2012

A mode-singular-value-decomposition (SVD) maximum likelihood (ML) estimation procedure is proposed for the source localization problem under an additive measurement error model. In a practical situation, the noise variance is usually unknown. In this paper, we propose an algorithm that does not require the noise covariance matrix as a priori knowledge. In the proposed method, the weight is derived by the inverse of the noise magnitude square in the ML criterion. The performance of the proposed method outperforms that of the existing methods and approximates the Taylor-series ML and Cram$\acute{e}$r-Rao lower bound.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1905-1910
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• 2003

It is well known that parameter uncertainties and time-delays cannot be avoided in practice and result in poor performance and even instability. Nevertheless, to the authors' best knowledge, there exist few results on model predictive control (MPC) handling explicitly uncertain time-delayed systems. In this paper, we present an MPC algorithm for uncertain time-varying systems with input constraints and state-delay. An optimization problem is suggested to find a memoryless state-feedback MPC law and the closed-loop stability is established under feasibility and certain conditions.

• The Journal of Society for e-Business Studies
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• v.22 no.3
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• pp.1-28
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• 2017

Today, according to the increased importance of industry-university cooperation in the knowledge-based economy, support and the number of researches involved in industry-university cooperation has also steadily increased. But it is true that profits from the outcome of patents resulting from such cooperation, such as technology transfer and royalty fees, are lower than they are supposed to be, because of excessive patents applications, although some of them have little commercial potential. Therefore, this research aims to suggest a way to analyze and recognize patents, which enable efficient industry-university cooperation and technology transfer. For the analysis, data on 1,061 patents was collected from 4 different universities. With the data, a quality-strategy matrix was arranged targeting the industry-university cooperation foundations', US patents owned by universities, text mining, and social network analysis were carried out, particularly focusing on the patents in the advanced quality technology section of the matrix. Then core key words and IPC codes were obtained and key patents were analyzed by universities. As a result of the analysis, it was found that 4 key patents, 2 key IPC codes were drawn for University H, 4 key patents, 2 key IPC codes for University K, 6 key patents, 1 key IPC code for University Y, 14 key patents, and 2 key IPC codes for University S. This research is expected to have a great significance in contributing to the invigoration of industry-university cooperation based on the analysis result on patents and IPC codes, which enable efficient industry-university cooperation and technology transfer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5C
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• pp.527-539
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• 2009

In this paper, we propose an asynchonous ICI (Inter-Cell Interference) mitigation techniques for 3GPP LTE MIMO-OFDMA down-link receiver. An increasing in symbol timing misalignments may occur relative to sychronous network as the result of BS (Base Station) timing differences. Such symbol synchronization errors that exceed the guard interval or the cyclic prefix duration may result in MAI (Multiple Access Interference) for other carriers. In particular, at the cell boundary, this MAI becomes a critical factor, leading to degraded channel throughput and severe asynchronous ICI. Hence, many researchers have investigated the interference mitigation method in the presence of asynchronous ICI and it appears that the knowledge of the SCM (Spatial Covariance Matrix) of the asynchronous ICI plus background noise is an important issue. Generally, it is assumed that the SCM estimated by using training symbols. However, it is difficult to measure the interference statistics for a long time and training symbol is also not appropriate for MIMO-OFDMA system such as LTE. Therefore, a noise reduction method is required to improve the estimation accuracy. Although the conventional time-domain low-pass type weighting method can be effective for noise reduction, it causes significant estimation error due to the spectral leakage in practical OFDM system. Therefore, we propose a time-domain sinc type weighing method which can not only reduce the noise effectively minimizing estimation error caused by the spectral leakage but also implement frequency-domain moving average filter easily. By using computer simulation, we show that the proposed method can provide up to 3dB SIR gain compared with the conventional method.

• Journal of Science Education
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• v.37 no.2
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• pp.323-337
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• 2013

The purpose of this study was to analyze the scientific reasoning ability during open-inquiry activities of science-gifted 2nd middle school students. Open-inquiry activity is similar to process of scientists' science knowledge generation. Identifying and analyzing the scientific reasoning process and the scientific reasoning ability during open-inquiry activities of science-gifted students, will be able to provide implications for future research. CSRI Matrix(Dolan & Grady, 2010) was used to analyze the complexity of the scientific reasoning ability. The higher degree of complexity of the scientific reasoning is similar to process of scientists' science knowledge generation. The results showed that each process of the open-inquiry activities were distributed by various steps of complexity of the scientific reasoning. Particularly, 'The generating questions' and 'Connecting data to the research question' were 'most complex' step in all teams. On the other side, 'Posing preliminary hypotheses', 'Selecting dependent and independent variables', 'Considering the limitations or flaws of their experiments' were low steps in most teams. And 'Communicating and defending findings' was distributed by most various steps of complexity of the scientific reasoning.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.398-400
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• 2011

Purpose: Subungual tumors are a common cause of nail plate deformity, and may be caused by fibrokeratoma, Koene's tumor and glomus tumors. Neurofibromas, either as part of neurofibromatosis or as a solitary tumor are exceptionally rare in the digits. Methods: A 44-year-old man presented with painless onychodystrophy and nail plate elevation of the right thumb due to a small subungual mass that had started growing 3 years ago. Sensory evaluation of the distal phalanx was normal, and no discoloration nor infection signs were seen. The nail plate was extracted under local anesthesia, and the mass was delicately removed without injury to the nail bed. The nail matrix was repaired with primary closure. Results: Histopathology shows a well circumscribed, cellular tumor with myxoid stroma. Tumor cells were S-100 protein positive, and the patient was diagnosed with myxoid neurofibroma. There has been no sign of recurrence to date, 14 months after the operation. Conclusion: Presentation of cutaneous neurofibromas in the digits is an uncommon finding. They may occur as a manifestation of neurofibromatosis or as a solitary tumor. Subungual neurofibromas are exceptionally rare. To our knowledge, there are only ten reports of solitary subungual neurofibroma unrelated to neurofibromatosis to date. We report a rare case of solitary subungual myxoid neurofibroma of the thumb, that was treated through total excision, with preservation of the nail matrix.

• Structural Engineering and Mechanics
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• v.31 no.2
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• pp.137-152
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• 2009

Mechanic behavior of Y-shape thin-walled box girder bridge structure is complex, so one can not exactly hold the mechanical behavior of the Y-shape thin-walled box girder bridge structure through general calculation theory and analytical method. To hold the mechanical behavior better, based on elementary beam theory, by increasing the degree of freedom analytical method, taking account of restrained torsiondistortion angledistortion warp and shearing lag effect at the same time, authors obtain a thin-walled box beam analytical element of 10 degrees of freedom of every node, derive stiffness matrix of the element, and code a finite element procedure. In addition, authors combine the obtained procedure with spatial grillage analytical method, meanwhile, they build a new analytical method that is the spatial thin-walled box girder element grillage analysis method. In order to validate the precision of the obtained analysis method, authors analyze a type Y-shape thin-walled box girder bridge structure according to the elementary beam theory analytical method, the shell theory analytical method and the spatial thin-walled box girder element grillage analysis method respectively. At last, authors test a type Y-shape thin-walled box girder bridge structure. Comparisons of the results of theory analysis with the experimental text show that the spatial thin-walled box girder element grillage analysis method is simple and exact. The research results are helpful for the knowledge of the mechanics property of these Y-shape thin-walled box girder bridge structures.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.4
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• pp.437-445
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• 2023

A space system refers to a network of sensors, ground systems, and space-craft operating in space. The security of space systems relies on information systems and networks that support the design, launch, and operation of space missions. Characteristics of space operations, including command and control (C2) between space-craft (including satellites) and ground communication, also depend on wireless frequency and communication channels. Attackers can potentially engage in malicious activities such as destruction, disruption, and degradation of systems, networks, communication channels, and space operations. These malicious cyber activities include sensor spoofing, system damage, denial of service attacks, jamming of unauthorized commands, and injection of malicious code. Such activities ultimately lead to a decrease in the lifespan and functionality of space systems, and may result in damage to space-craft and, lead to loss of control. The Cybersecurity Adversarial Tactics, Techniques, and Common Knowledge (ATT&CK) matrix, proposed by Massachusetts Institute of Technology Research and Engineering (MITRE), consists of the following stages: Reconnaissance, Resource Development, Initial Access, Execution, Persistence, Privilege Escalation, Defense Evasion, Credential Access, Discovery, Lateral Movement, Collection, Command & Control, Exfiltration, and Impact. This paper identifies cybersecurity activities in space systems and satellite navigation systems through the National Institute of Standards and Technology (NIST)'s standard documents, former U.S. President Trump's executive orders, and presents risk management activities. This paper also explores cybersecurity's tactics attack techniques within the context of space systems (space-craft) by referencing the Sparta ATT&CK Matrix. In this paper, security threats in space systems analyzed, focusing on the cybersecurity attack tactics, techniques, and countermeasures of space-craft presented by Space Attack Research and Tactic Analysis (SPARTA). Through this study, cybersecurity attack tactics, techniques, and countermeasures existing in space-craft are identified, and an understanding of the direction of application in the design and implementation of safe small satellites is provided.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.6
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• pp.456-463
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• 2002

Distraction osteogenesis is a well-established clinical treatment for limb length discrepancy and skeletal deformities. Appropriate mechanical tension-stress is believed not to break the callus but rather to stimulate osteogenesis. In contrast to fracture healing, the mode of bone formation in distraction osteogenesis is primarily intramembranous ossification. Although the biomechanical, histological, and ultrastructural changes associated with distraction osteogenesis have been widely described, the basic biology of the process is still not well known. Moreover, the molecular mechanisms in distraction osteogenesis remain largely unclear. Recent studies have implicated the growth factor cascade is likely to play an important role in distraction. And current reserch suggested that mechanical tension-stress modulates cell shape and phenotype, and stimulates the expression of the mRNA for bone matrix proteins. This article presents the hypotheses and current research that have furthered knowledge of the molecular biology that govern distraction osteogenesis. The gene regulation of growth factors and extracellular matrix proteins during distraction osteogenesis are discussed in this article. It is believed that understanding the biomolecular mechanisms that mediate distraction osteogenesis may guide the development of targeted strategies designed to improve distraction osteogenesis and accelerate bone healing.