• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.10
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• pp.995-1004
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• 2014

Due to the development of spectrum use technology and various services based on radio spectrum, the scarcity of spectrum has been heightened. In this circumstances both the efficiency and fairness of spectrum use need to be raised. Open spectrum access can be a useful approach for both goal. For the open spectrum access the legal institution needs to be reformed to enable it. From the starting point of spectrum use till the end of spectrum use there can be various issues of rights and obligations. So the legal institution for various legal status of spectrum use and establishment and continuous management of DB and fast and respectable dispute resolution mechanism is required.

• Journal of KIISE:Software and Applications
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• v.31 no.4
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• pp.457-466
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• 2004

Recommendation is to offer information which fits user's interests and tastes to provide better services and to reduce information overload. It recently draws attention upon Internet users and information providers. The collaborative filtering is one of the widely used methods for recommendation. It recommends an item to a user based on the reference users' preferences for the target item or the target user's preferences for the reference items. In this paper, we propose a neural network based collaborative filtering method. Our method builds a model by learning correlation between users or items using a multi-layer perceptron. We also investigate integration of diverse information to solve the sparsity problem and selecting the reference users or items based on similarity to improve performance. We finally demonstrate that our method outperforms the existing methods through experiments using the EachMovie data.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.2
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• pp.18-25
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• 2016

Bascule bridge, with its use to help vessels ply, has a several examples overseas of being serviced for more than decades years by careful maintenance, admitted its significance as landmarks for its rareness. Yeongdo Bridge, the sole bascule bridge in Korea was reconstructed in 2013 after being demolished because of its corrosion and aging, and now operates once in a day. Recently, safety inspections are executed thanks to demands getting higher for maintenance and safety of bridges, but measurement and analysis about bascule bridges are scarce. This study includes the analysis of the bascule bridge's behavior such as stress, vibration and reaction in normal condition and while it lifts up, based on measurement. We expect that this study will be used as an initial data to compare and confirm bridge's changes as service year and the number of operation increase.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.5
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• pp.643-648
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• 2005

In order to supply services necessary for users intelligently in the ubiquitous computing, effective filtering of context information is necessary. But studies of context information filtering have not been made much yet. In order for filtering of context information, we can use collaborative filtering being used much at electric commerce, etc. In order to use such collaborative filtering method in the filtering of ubiquitous computing environment, we must solve such problems as first rater problem, sparsity problem, stored data problem and etc. In this study, in order to solve such problems, the researcher proposes the collaborative filtering method using types of context information. And as the result of applying this filtering method to MAUCA, the P2P mobile agent system, the researcher could confirm the average result of 7.7% in the aspect of service supporting function.

• FLOWER RESEARCH JOURNAL
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• v.18 no.4
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• pp.308-314
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• 2010

Importance of color in floral design has been emphasized for long time, but it is difficult to find out standardization of color for floral design and for educational system. Wedding bouquet is major and important part of floral design and it shows same problem. The research is concentrated on color image analysis of wedding bouquet designs which have been submitted for 'Interflora World Cup Competition' with the intention to utilize the study result as the basic information of floral design. Colors of wedding bouquets from 20 different countries were analyzed. All of designers chose high brightness and saturation more for designing the bouquets. Warm colors and cold colors have been taken in similar portion. Blue color has been rarely used and it is probably because of the rarity of blue flowers. This study shows each continent has different color preference. European designers used wide variety of colors while Asian designers preferred red color. From this study, we found that color image scales of wedding bouquets represent 8 images out of 12 representative images. Four exceptions are 'clean', 'elegant', 'gentle' and 'modern' images.

• The Journal of the Acoustical Society of Korea
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• v.38 no.5
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• pp.543-548
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• 2019

The tonal signal caused by the machinery component of a vessel such as an engine, gearbox, and support elements, can be modeled as a sparse signal in the frequency domain. Recently, compressive sensing based techniques that recover an original signal using a small number of measurements in a short period of time, have been applied for the tonal frequency detection. These techniques, however, cannot avoid a basis mismatch error caused by the discretization of the frequency domain. In this paper, we propose a method to detect the tonal frequency with a small number of measurements in the continuous domain by using the atomic norm minimization technique. From the simulation results, we demonstrate that the proposed technique outperforms conventional methods in terms of the exact recovery ratio and mean square error.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.460-465
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• 2021

In active sonar, time delay estimation is used to find the distance between the target and the sonar. Among the time delay estimation methods for active sonar, estimation in the frequency domain is widely used. When estimating in the frequency domain, the time delay can be thought of as a frequency estimator, so it can be used relatively easily. However, this method is prone to rapid increase in error due to noise. In this paper, we propose a new method which applies weighted dictionary and sparsity in order to reduce this error increase and we extend it to two receivers to propose an algorithm for estimating the time delay between two receivers. And the case of applying the proposed method and the case of not applying the proposed method including the conventional frequency domain algorithm and Generalized Cross Correlation-Phase transform (GCC-PHAT) in a white noise environment were compared with one another. And we show that the newly proposed method has a performance gain of about 15 dB to about 60 dB compared to other algorithms.

• Journal of Digital Convergence
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• v.17 no.2
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• pp.113-125
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• 2019

Mobile social commerce is one of the fastest growing distribution channels in recent years. Therefore, it is important to understand customer's buying behavior in mobile social commerce in order to continuously grow in the competitive mobile social commerce market. To achieve the purpose of this study is to investigate how impulsive buying behaviors are applied in mobile shopping and how factors affect impulse purchasing in online shopping. In order to verify the hypothesis, we surveyed the customers who have experiences of using mobile social commerce and analyzed 280 valid data by Smart PLS 3.0. As a result, it was confirmed that consumers' innovation and purchasing experience influenced impulse purchase in mobile social commerce, and scarcity messages among information attributes affect impulse buying. Through this study, impulsive buying behavior which is a frequently analyzed variable in an online shopping context will be extended to the mobile shopping context. and it will provide practical implications for customer strategy establishment in mobile social commerce market.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.1
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• pp.25-32
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• 2019

The urban river has played an important role in biodiversity by providing various waterside areas in urban areas that are difficult for organisms to live in. The river is also used as a resting place and experience space for citizens. In particular, Yeouido Saetgang is the first ecological park in Korea, and it is located in the heart of downtown Seoul, making it highly valuable for its location and ecological value. However, water quality issues have continuously been raised since the construction project of Yeouido Saetgang river. So it is necessary to investigate the environment state and analyze the causes of the environment deterioration. In this study, the causes of the river stagnation and water quality deterioration in Yeouido Saetgang river were analyzed. For this, river surveys and aerial photo analysis were used to analyze the causes of difficulties in natural water circulation. Also, the results of monitoring water quality showed that the averaged level of BOD and T-P in dry season is III and IV, respectively, while that of BOD and T-P are V~VI in rainy season. In addition, through the drainage analysis of sewer network, small drainages that affect the water quality in Saetgang river was selected and discussed.

• Korean Journal of Heritage: History & Science
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• v.49 no.4
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• pp.218-227
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• 2016

Protected Flora are natural heritage that involve a wide variety of valuable natural values and cultural values. Over time, "Cultural Properties Preservation Law" has been changing the definition and the criteria of Protected Flora. In addition to the academic value and the rarity of the plant, historical, ethnic and landscape values have become increasingly important. For that reason the declaration and management processes of the Protected Flora need to be improved. However, the current statute has focused on the morphological characteristics of the plants which have a limit to encompass various values of the plant. It also does not correspond to the definition of Protected Flora and its declaration criteria stated on the "Cultural Properties Preservation Law." For this reason, the main purpose of this study is to develop new types of Protected Flora so that various Protected Flora can be discovered in the future.