• Title/Summary/Keyword: Knowledge Interference

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A Study on The Expressive Characteristics of Transparent Materials in Interior Design (실내디자인에 있어 투명성 재료의 표현 특성에 관한 연구)

  • Lee, Gyoo-Baek
    • Korean Institute of Interior Design Journal
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    • v.18 no.4
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    • pp.43-50
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    • 2009
  • Design trend, transparency, which has been developed under a reflection of current periodic environment, has been exposed to people all over the world through varieties of architecture facade and interior space. As interior space follows this trend, which has difference in showing space from the past, transparency becomes an important measure of showing openness of certain space. Main objective of this research is to understand a characteristics of materials that leads transparency a important measure to the modern interior design, and this will set the range to this applicable materials for appropriate areas of defining transparency in an interior. Characteristic uses of transparent materials found in this research which leads transparency into interior space are described below: First, there are two perspectives in transparency. One is visibility and material wised transparency and the other is conditional and spacial wised transparency. With this knowledge, we can expand a level of transparency with ideas such as clarity, opacity, visible transmission, and reflection, and this broadened range will vary the acceptable materials used to show transparency. Second, transparent materials are used with many different purposes in modern interior space as furnitures, sanitary fixtures, partitions, and other structures. With using modern technology in reforming this materials brought new methods in structure composing. last, transparent materials' expnt pable characteristics made modern interior space to have a control over spacial homogeneity, a simplified octlines, weakened boundaries, and compositional effects by interference and vision.

Transport Protocols in Cognitive Radio Networks: A Survey

  • Zhong, Xiaoxiong;Qin, Yang;Li, Li
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.11
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    • pp.3711-3730
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    • 2014
  • Cognitive radio networks (CRNs) have emerged as a promising solution to enhance spectrum utilization by using unused or less used spectrum in radio environments. The basic idea of CRNs is to allow secondary users (SUs) access to licensed spectrum, under the condition that the interference perceived by the primary users (PUs) is minimal. In CRNs, the channel availability is uncertainty due to the existence of PUs, resulting in intermittent communication. Transmission control protocol (TCP) performance may significantly degrade in such conditions. To address the challenges, some transport protocols have been proposed for reliable transmission in CRNs. In this paper we survey the state-of-the-art transport protocols for CRNs. We firstly highlight the unique aspects of CRNs, and describe the challenges of transport protocols in terms of PU behavior, spectrum sensing, spectrum changing and TCP mechanism itself over CRNs. Then, we provide a summary and comparison of existing transport protocols for CRNs. Finally, we discuss several open issues and research challenges. To the best of our knowledge, our work is the first survey on transport protocols for CRNs.

An Optimal Orthogonal Overlay for Fixed MIMO Wireless Link (고정된 MIMO 환경에서의 최적의 직교 오버레이 시스템 설계)

  • Yun, Yeo-Hun;Cho, Joon-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.10C
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    • pp.929-936
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    • 2009
  • In this paper, we consider designing a multi-input multi-output (MIMO) overlay system for fixed MIMO wireless link, where a frequency flat narrowband channel is shared by multiple transmitter and receiver pairs. Assuming the perfect knowledge of the second-order statistics of the received legacy signals and the composite channels from the overlay transmitter to the legacy receivers, the jointly optimal linear precoder and decoder matrices of the MIMO overlay system is derived to minimize the total mean squared error (MSE) of the data symbol vector, subject to total average transmission power and zero interference induced to legacy MIMO systems already existing in the frequency band of interest. Furthermore, the necessary and sufficient condition for the existence of the optimal solution is also derived.

SPMC-MAC : Slim Preamble Multi-Channel MAC Protocol with Transmission Power Control in Wireless Sensor Networks (무선 센서 네트워크에서 다중 채널과 전송세기 제어를 이용한 맥 프로토콜)

  • Yoon, Jang-Muk;Bahk, Sae-Woong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.10B
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    • pp.876-884
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    • 2008
  • In this paper, we propose an asynchronous MAC protocol to minimize energy usage and to maximize data throughput for a wireless sensor network in multi channel environments. Our proposed SPMC-MAC (Slim Preamble Multi-Channel Media Access Control) adopts the preamble sliming mechanism proposed in [6] that takes advantage of the knowledge about the wakeup time of the receiver node. The preamble contains the receiver's ID and a randomly selected channel ID for data communication, and it is transmitted over a dedicated common channel. The power control has the benefit of keeping an appropriate number of nodes with the communication range, resulting in reduced collision and interference. We compare our SPMC-MAC and X-MAC extensively in terms of energy consumption and throughput using mathematical analysis and simulation.

Influence of Adjacent Structures on Surface-Wave Dispersion Characteristics and 2-D Resistivity Structure (표면파 분산특성과 전기비저항 분포특성에 대한 인접구조물의 영향)

  • Joh, Sung-Ho;Kim, Bong-Chan;Cho, Mi-Ra;Kim, Suhk-Chol;Youn, Dae-Hee;Hong, Jae-Ho
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.1318-1327
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    • 2008
  • Geotechnical sites in urban areas may have embedded structures such as utility lines and underground concrete structures, which cause difficulties in site investigation. This study is a preliminary research to establish knowledge base for developing an optimal technique for site investigation in urban areas. Surface-wave method and resistivity survey, which are frequently adopted for non-destructive site-investigation for geotechnical sites, were investigated to characterize effects of adjacent structures. In case of surface wave method, patterns of wave propagation were investigated for typical sets of multi-layered geotechnical profiles by numerical simulation based on forward modeling theory and field experiments for small-size model tests and real-scale tests in the field. In case of resistivity survey, 3-D finite element analyses and field tests were performed to investigate effects of adjacent concrete structures. These theoretical and experimental researches for surface-wave method and resistivity survey resulted in establishing physical criteria to cause interference of adjacent structures in site investigation at urban areas.

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Two-stage ML-based Group Detection for Direct-sequence CDMA Systems

  • Buzzi, Stefano;Lops, Marco
    • Journal of Communications and Networks
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    • v.5 no.1
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    • pp.33-42
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    • 2003
  • In this paper a two-stage maximum-likelihood (ML) detection structure for group detection in DS/CDMA systems is presented. The first stage of the receiver is a linear filter, aimed at suppressing the effect of the unwanted (i.e., out-of-grout) users' signals, while the second stage is a non-linear block, implementing a ML detection rule on the set of desired users signals. As to the linear stage, we consider both the decorrelating and the minimum mean square error approaches. Interestingly, the proposed detection structure turns out to be a generalization of Varanasi's group detector, to which it reduces when the system is synchronous, the signatures are linerly independent and the first stage of the receiver is a decorrelator. The issue of blind adaptive receiver implementation is also considered, and implementations of the proposed receiver based on the LMS algorithm, the RLS algorithm and subspace-tracking algorithms are presented. These adaptive receivers do not rely on any knowledge on the out-of group users' signals, and are thus particularly suited for rejection of out-of-cell interference in the base station. Simulation results confirm that the proposed structure achieves very satisfactory performance in comparison with previously derived receivers, as well as that the proposed blind adaptive algorithms achieve satisfactory performance.

Improving aeroelastic characteristics of helicopter rotor blades in forward flight

  • Badran, Hossam T.;Tawfik, Mohammad;Negm, Hani M.
    • Advances in aircraft and spacecraft science
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    • v.6 no.1
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    • pp.31-49
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    • 2019
  • Flutter is a dangerous phenomenon encountered in flexible structures subjected to aerodynamic forces. This includes aircraft, helicopter blades, engine rotors, buildings and bridges. Flutter occurs as a result of interactions between aerodynamic, stiffness and inertia forces on a structure. The conventional method for designing a rotor blade to be free from flutter instability throughout the helicopter's flight regime is to design the blade so that the aerodynamic center (AC), elastic axis (EA) and center of gravity (CG) are coincident and located at the quarter-chord. While this assures freedom from flutter, it adds constraints on rotor blade design which are not usually followed in fixed wing design. Periodic Structures have been in the focus of research for their useful characteristics and ability to attenuate vibration in frequency bands called "stop-bands". A periodic structure consists of cells which differ in material or geometry. As vibration waves travel along the structure and face the cell boundaries, some waves pass and some are reflected back, which may cause destructive interference with the succeeding waves. In this work, we analyze the flutter characteristics of a helicopter blades with a periodic change in their sandwich material using a finite element structural model. Results shows great improvements in the flutter forward speed of the rotating blade obtained by using periodic design and increasing the number of periodic cells.

The Relationship Between Three-Level Review System and Audit Quality: Empirical Evidence from China

  • TANG, Kai;YAN, Sibei;BAE, Khee Su
    • The Journal of Asian Finance, Economics and Business
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    • v.9 no.5
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    • pp.135-145
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    • 2022
  • To improve audit quality, certain Chinese auditing firms have added a third-level review by an additional signing auditor to the general evaluation by a signing auditor team consisting of an engagement auditor and a partner. Nonetheless, our research-based on 36,033 firm-year observations from 2004 to 2019 reveals that compared to the general review system, auditor teams under the three-level review system are less likely to issue modified audit opinions when abnormal financial conditions arise. This finding suggests that, while larger auditor teams' knowledge, experience, and information advantages can theoretically sharpen their judgment, their performance is more susceptible to interference from divergent opinions, the diffusion of responsibility, and lower energy invested by individual auditors, ultimately impairing their judgment regarding the audited enterprises' abnormal financial conditions. That is, the three-level review system, which aims to improve audit quality, actually worsens audit quality. This conclusion remains valid after the problems of heteroscedasticity and endogeneity are addressed by using firm-level cluster robust standard errors and two-stage regression. We hope that our research will draw the attention of auditing firms, prompting them to reconsider the rationality of the three-level review system.

A Study on Knowledge Entity Extraction Method for Individual Stocks Based on Neural Tensor Network (뉴럴 텐서 네트워크 기반 주식 개별종목 지식개체명 추출 방법에 관한 연구)

  • Yang, Yunseok;Lee, Hyun Jun;Oh, Kyong Joo
    • Journal of Intelligence and Information Systems
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    • v.25 no.2
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    • pp.25-38
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    • 2019
  • Selecting high-quality information that meets the interests and needs of users among the overflowing contents is becoming more important as the generation continues. In the flood of information, efforts to reflect the intention of the user in the search result better are being tried, rather than recognizing the information request as a simple string. Also, large IT companies such as Google and Microsoft focus on developing knowledge-based technologies including search engines which provide users with satisfaction and convenience. Especially, the finance is one of the fields expected to have the usefulness and potential of text data analysis because it's constantly generating new information, and the earlier the information is, the more valuable it is. Automatic knowledge extraction can be effective in areas where information flow is vast, such as financial sector, and new information continues to emerge. However, there are several practical difficulties faced by automatic knowledge extraction. First, there are difficulties in making corpus from different fields with same algorithm, and it is difficult to extract good quality triple. Second, it becomes more difficult to produce labeled text data by people if the extent and scope of knowledge increases and patterns are constantly updated. Third, performance evaluation is difficult due to the characteristics of unsupervised learning. Finally, problem definition for automatic knowledge extraction is not easy because of ambiguous conceptual characteristics of knowledge. So, in order to overcome limits described above and improve the semantic performance of stock-related information searching, this study attempts to extract the knowledge entity by using neural tensor network and evaluate the performance of them. Different from other references, the purpose of this study is to extract knowledge entity which is related to individual stock items. Various but relatively simple data processing methods are applied in the presented model to solve the problems of previous researches and to enhance the effectiveness of the model. From these processes, this study has the following three significances. First, A practical and simple automatic knowledge extraction method that can be applied. Second, the possibility of performance evaluation is presented through simple problem definition. Finally, the expressiveness of the knowledge increased by generating input data on a sentence basis without complex morphological analysis. The results of the empirical analysis and objective performance evaluation method are also presented. The empirical study to confirm the usefulness of the presented model, experts' reports about individual 30 stocks which are top 30 items based on frequency of publication from May 30, 2017 to May 21, 2018 are used. the total number of reports are 5,600, and 3,074 reports, which accounts about 55% of the total, is designated as a training set, and other 45% of reports are designated as a testing set. Before constructing the model, all reports of a training set are classified by stocks, and their entities are extracted using named entity recognition tool which is the KKMA. for each stocks, top 100 entities based on appearance frequency are selected, and become vectorized using one-hot encoding. After that, by using neural tensor network, the same number of score functions as stocks are trained. Thus, if a new entity from a testing set appears, we can try to calculate the score by putting it into every single score function, and the stock of the function with the highest score is predicted as the related item with the entity. To evaluate presented models, we confirm prediction power and determining whether the score functions are well constructed by calculating hit ratio for all reports of testing set. As a result of the empirical study, the presented model shows 69.3% hit accuracy for testing set which consists of 2,526 reports. this hit ratio is meaningfully high despite of some constraints for conducting research. Looking at the prediction performance of the model for each stocks, only 3 stocks, which are LG ELECTRONICS, KiaMtr, and Mando, show extremely low performance than average. this result maybe due to the interference effect with other similar items and generation of new knowledge. In this paper, we propose a methodology to find out key entities or their combinations which are necessary to search related information in accordance with the user's investment intention. Graph data is generated by using only the named entity recognition tool and applied to the neural tensor network without learning corpus or word vectors for the field. From the empirical test, we confirm the effectiveness of the presented model as described above. However, there also exist some limits and things to complement. Representatively, the phenomenon that the model performance is especially bad for only some stocks shows the need for further researches. Finally, through the empirical study, we confirmed that the learning method presented in this study can be used for the purpose of matching the new text information semantically with the related stocks.

Evaluation of Consumer Nutrition Education Program to Reduce Sodium Intake Based on Social Cognitive Theory (사회인지론에 근거한 나트륨 섭취 줄이기 소비자 영양교육 프로그램의 효과 평가)

  • Ahn, So-Hyun;Kwon, Jong Sook;Kim, Kyung Min;Yoon, Jin-Sook;Kim, Hye-Kyeong
    • Korean Journal of Community Nutrition
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    • v.20 no.6
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    • pp.433-446
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    • 2015
  • Objectives: This study was performed to evaluate the consumer education program for reducing sodium intake based on social cognitive theory (SCT) and investigate consumer perceptions of environmental, cognitive and behavioral factors. Methods: Consumers (n=4,439) were recruited nationwide in Korea to participate in a nutrition education program for reducing sodium intake which was targeted on senior housewives (SH), parents (P), and office workers (OW). Questions regarding main factors of SCT were asked both before and after the education program. Results: SH and P recognized external social efforts and information to reduce sodium including nutrition labeling more than OW. The main barriers to practice reducing sodium intake were limited choice of low sodium food and menu, interference with social relationship when dining with others, and limited information, knowledge and skills. SH had lower barriers to practice reducing sodium intake and OW perceived 'preference to soup or stew' and 'preference to Kimchi, salted fish and fermented sauces' as barriers more than other groups at the baseline. Less than 50% of participants knew the relationship between sodium and salt, sodium in nutrition labeling, and recommended sodium intake. In addition, OW had little knowledge for capability to reduce sodium intake and lower self-efficacy to practice compared with SH and P. After education, positive outcome expectations such as lowering blood pressure, prevention of cardiovascular disease and osteoporosis were increased and barriers to practice reducing sodium intake were decreased in all groups (p < 0.05). The knowledge for behavioral capability and self-efficacy to reduce sodium intake were also improved but OW had still lower scores compared with other groups. Conclusions: These results suggested that nutrition education programs could be an effective tool to impact general population by facilitating awareness and increased capability to reduce sodium intake.