• Proceedings of the KSRS Conference
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• v.2
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• pp.1011-1014
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• 2006

Coarse resolution (9 - 50 km pixels) Sea Surface Temperature satellite data are frequently considered adequate for open ocean research. However, coastal regions, including coral reef, estuarine and mesoscale upwelling regions require high-resolution (1-km pixel) SST data. The AVHRR SST data often suffer from navigation errors of several kilometres and still require manual navigation adjustments. The second serious problem is faulty and ineffective cloud-detection algorithms used operationally; many of these are based on radiance thresholds and moving window tests. With these methods, increasing sensitivity leads to masking of valid pixels. These errors lead to significant cold pixel biases and hamper image compositing, anomaly detection, and time-series analysis. Here, after manual navigation of over 40,000 AVHRR images, we implemented a new cloud filter that differs from other published methods. The filter first compares a pixel value with a climatological value built from the historical database, and then tests it against a time-based median value derived for that pixel from all satellite passes collected within ${\pm}3$ days. If the difference is larger than a predefined threshold, the pixel is flagged as cloud. We tested the method and compared to in situ SST from several shallow water buoys in the Florida Keys. Cloud statistics from all satellite sensors (AVHRR, MODIS) shows that a climatology filter with a $4^{\circ}C$ threshold and a median filter threshold of $2^{\circ}C$ are effective and accurate to filter clouds without masking good data. RMS difference between concurrent in situ and satellite SST data for the shallow waters (< 10 m bottom depth) is < $1^{\circ}C$, with only a small bias. The filter has been applied to the entire series of high-resolution SST data since1993 (including MODIS SST data since 2003), and a climatology is constructed to serve as the baseline to detect anomaly events.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.227-236
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• 2008

The kind of concrete generally used in steel concrete composite bridges is normal-weight concrete whose unit weight is ${2,300kg/m^{3}}$. However, using lightweight concrete in composite bridges diminishes the sectional forces due to the self-weight of concrete decks. As a result, this will make the bridge design more economical. The type of concrete deck that could be adopted in composite bridges using lightweight con crete may be classified into Cast-In-Place (C.I.P.) concrete deck and precast concrete deck. These two types of decks have some differences with respect to structural behavior and constructional method, and hence,structural behavior of stud shear connectors that connect a concrete deck to a steel girder is changed with the type of deck used. In this study, push-out tests were conducted to evaluate the characteristics of static behavior of the stud shear connectors with a precast deck using lightweight concrete. Also, additional precast deck specimens with bedding layer that had shear keys and devices for transverse confinement of the bedding layer for the prevention of cracks occurring in the bedding layer were tested. These cracks The efficiency of these devices was then evaluated.

• KSCI Review
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• v.14 no.2
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• pp.185-197
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• 2006

A star schema consists of a central fact table, which is surrounded by one or more dimension tables. Each row int the fact table contains a multi-part primary key(or a composite foreign key) along with one or more columns containing various facts about the data stored in the row Each of the composit foreign key components is related to a dimensional table. The combination of keys in the fact table creates a composite foreign key that is unique to the fact table record. The composite foreign key, however, is rarely unique to the fact table record in real-world applications, particularly in financial applications. In order to make the composite foreign key be the determinant in real-world application, some precalculation might be performed in the SQL relational database, and cached in the OLAP database. However, there are many drawbacks to this approach. In some cases, this approach might give users the wrong results. In this paper, an approach to fact table modeling and related MDX query composing, which can be used in real-world applications without performing any precalculation and gives users the correct results, is proposed.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.8-14
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• 2020

Recently, there was an increasing demand for an integrated access control system which is capable of user recognition, door control, and facility operations control for smart buildings automation. The market available door lock access control solutions need to be improved from the current level security of door locks operations where security is compromised when a password or digital keys are exposed to the strangers. At present, the access control system solution providers focusing on developing an automatic access control system using (RF) based technologies like bluetooth, WiFi, etc. All the existing automatic door access control technologies required an additional hardware interface and always vulnerable security threads. This paper proposes the user identification and authentication solution for automatic door lock control operations using camera based visible light communication (VLC) technology. This proposed approach use the cameras installed in building facility, user smart devices and IoT open source controller based LED light sensors installed in buildings infrastructure. The building facility installed IoT LED light sensors transmit the authorized user and facility information color grid code and the smart device camera decode the user informations and verify with stored user information then indicate the authentication status to the user and send authentication acknowledgement to facility door lock integrated camera to control the door lock operations. The camera based VLC receiver uses the artificial intelligence (AI) methods to decode VLC data to improve the VLC performance. This paper implements the testbed model using IoT open-source based LED light sensor with CCTV camera and user smartphone devices. The experiment results are verified with custom made convolutional neural network (CNN) based AI techniques for VLC deciding method on smart devices and PC based CCTV monitoring solutions. The archived experiment results confirm that proposed door access control solution is effective and robust for automatic door access control.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.1
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• pp.64-77
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• 2009

A proxy re-encryption scheme allows Alice to temporarily delegate the decryption rights to Bob via a proxy. Alice gives the proxy a re-encryption key so that the proxy can convert a ciphertext for Alice into the ciphertext for Bob. Recently, ID-based proxy re-encryption schemes are receiving considerable attention for a variety of applications such as distributed storage, DRM, and email-forwarding system. And a non-interactive identity-based proxy re-encryption scheme was proposed for achieving CCA-security by Green and Ateniese. In the paper, we show that the identity-based proxy re-encryption scheme is unfortunately vulnerable to a collusion attack. The collusion of a proxy and a malicious user enables two parties to derive other honest users' private keys and thereby decrypt ciphertexts intended for only the honest user. To solve this problem, we propose two ID-based proxy re-encryption scheme schemes, which are proved secure under CPA and CCA in the random oracle model. For achieving CCA-security, we present self-authentication tag based on short signature. Important features of proposed scheme is that ciphertext structure is preserved after the ciphertext is re-encrypted. Therefore it does not lead to ciphertext expansion. And there is no limitation on the number of re-encryption.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.257-266
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• 2014

In this paper, we propose the development of an eBook Service System based on VOD Broadcasting Contents(eBSS-VOD) which protects the illegal copy through the effective DRM strategy. Here, eBSS-VOD is composed of three sub-systems - eBook server management system, ePub Builder, and eBook App - according to the functional points of view. The eBook server management system operates to manage the eBooks, the encription keys, the VOD contents, the membership and the history of users' viewing log. The ePub Builder assists to produce eBooks by DRM strategy. The eBook App provides users with the utility services of VOD viewing and eBook purchase processing. The proposed eBSS-VOD, differently from the current eBook systems, helps to increase the users' interests in reading books and to motivate the users' purchasing needs and it also makes new distribution channel for eBooks based on VOD broadcasting contents through smart applications. We provides the differentiated eBook builder which are based on ePub3.0 and DRM strategy. Through empirical survey results on users' interests and purchase intention for eBooks, we show that the proposed eBSS-VOD has the comparative effects compared to the current systems.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.3-3
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• 2017

The question of how to establish sustainable agricultural systems has become as prominent as questions related to water, energy and climate change. High input/high output agriculture has brought with it many adverse effects; the massive deterioration of soil and water in both quantity and quality, increased greenhouse gas emissions and an increased prevalence of unsafe foods. Additionally, urbanization and climate change has worsened the shortage of farmland and reduced the supply of agricultural water. Given these challenges, maintaining, conserving and efficiently using agri-environmental resources, through fostering of sustainable agriculture, have emerged as key tasks in solving these problems. What is needed therefore is research, based on systematic and comprehensive empirical analyses, that can propose plans and methods for establishing an appropriate sustainable agricultural system. The empirical analysis of sustainable agricultural system is approached separately from economic, environmental and social aspects. An analysis of environment effect reveals that the available phosphate level is 1.3~2.1 times greater than the optimal amount in rice paddies, upland fields and orchards. Further examination has revealed that the excess nutrient is polluting both ground water and surface water. Analytical results for economic feasibility show that factors of production have been invested heavily in the rice crop. Under these conditions, sustainable agriculture, including low-input agriculture, appears to be a possible alternative that will facilitate simultaneous improvements in both economic feasibility and environment effects. Analysis results for sociality reveal that social factors include the value of producer, association and interior networks. Social conditions are comprised of leadership, consumers' awareness, education and conflict solutions. In addition, analysis as to the degree investments contribute to improving agricultural value added has revealed that the direct payment program is the most effective instrument. Experts confirm that economic feasibility can be improved by scientific and well-reasoned nutrient management on the basis of soil testing. Farmers pointed to 'economic factors' as being the largest obstacle to switching to the practice of sustainable agriculture. They also indicate 'uncertainty with regards to sustainable agriculture technology' as an impediment to practicing sustainable agriculture. Even so, farmers who believe environmental and regional issues to be the most pressing problems have expanded their practice of sustainable agriculture. The keys to establishing sustainable agriculture system are classified into the following four aspects. Firstly, from an economic aspect, the research indicates that agricultural policy needs to be integrated with environmental policy and that the function of market making based on the value chain needs to be revitalized. Secondly, from an environmental aspect, there is a need for an optimal resource management system to be established in the agricultural sector. In addition, sustainable agriculture practice will need to be extended with attendant environmentally-friendly and sustainable intensive technology also requiring further development. Thirdly, from a social aspect, green agriculture management needs to be fostered, technology and education extended, and social conflict mediated. Lastly, from a governance aspect, it will be necessary to strengthen good governance, assign and share suitable roles and responsibilities, build a cooperation system and utilize community supported agriculture.

• Journal of the HCI Society of Korea
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• v.1 no.1
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• pp.21-28
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• 2006

Most of the commercialized wearable text input devices are wrist-worn keyboards that have adopted the minimization method of reducing keys. Generally, a drastic key reduction in order to achieve sufficient wearability increases KSPC(Keystrokes per Character), decreases text entry performance, and requires additional effort to learn a new typing method. We are faced with wearability-usability tradeoff problems in designing a good wearable keyboard. To address this problem, we introduced a new keyboard minimization method of reducing key pitch. From a series of empirical studies, we found the potential of a new method which has a keyboard with a 7mm key pitch, good wearability and social acceptance in terms of physical form factors, and allows users to type 15.0WPM in 3 session trials. However, participants point out that a lack of passive haptic feedback in keying action and visual feedback on users' input deteriorate the text entry performance. We have developed the One-key Keyboard that addresses this problem. The traditional desktop keyboard has one key per character, but the One-key Keyboard has only one key ($70mm{\times}35mm$) on which a 10*5 QWERTY key array is printed. The One-key Keyboard detects the position of the fingertip at the time of the keying event and figures out the character entered. We conducted a text entry performance test comprised of 5 sessions. The participants typed 18.9WPM with a 6.7% error rate over all sessions and achieved up to 24.5WPM. From the experiment's results, the One-key Keyboard was evaluated as a potential text input device for wearable computing, balancing wearability, social acceptance, input speed, and learnability.

• Journal of The Korean Association For Science Education
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• v.24 no.6
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• pp.1245-1255
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• 2004

The purpose of this study is to develop a valid and reliable evaluating instrument for elementary school fifth and sixth graders. The instrument is developed through R&D procedure, which includes two checks of science specialist and two field trials of the instrument. Evaluating items are content-free for each science inquiry skill. Each science inquiry element is based on SAPA and the 7th curriculum. This study has selected 10 science inquiry skills(observing, classifying, measuring, predicting, inferring, recognizing of a problem, controlling variables, interpreting data, drawing a conclusion, designing an experiment), formulated a clear definition of the elements of science inquiry skills, and established the objectives of evaluation. The content areas are divided into three categories, material and energy, life and environment, and the earth and circulation. Each category contains 10 items. So the instrument consists of 30 items. The content validity of items, objectivity of the scoring keys, and clarity of the items has been checked twice by specialists in science education. At the same time, two field trials were performed to produce the reliability of the instruments, discrimination index, and item difficulty index. The instrument has the content validity is 91.6%, reliability 0.79, objectivity 93.3%, discrimination index 0.30, and item difficulty index 66.1%.

• The Journal of the Korea Contents Association
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• v.16 no.7
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• pp.300-308
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• 2016

Research on OECD and Korea have shown that high-growth startups are the keys to job creation and that these companies are very important for economic growth. Given that the large-scale entry of women into the labor force accelerates economic growth and women have far lower levels of participation in growth-oriented entrepreneurship than men do, accelerating female entrepreneurship could have positive effects on the Korean economy. This paper uses data from several databases to do a comparison analysis between women's and men's start-ups to explore the factors that explain the lag in building high-growth firms among women. Women startups make up nearly 34% of startups(defined as less than 7 years of establishment), but only 6% of high-growth startups. Women rarely own large businesses, reflecting their low levels of initial capital and outside financing. Regardless of gender, entrepreneurs face many of the same challenges in starting businesses, but this study shows three primary factors for female entrepreneurs that lead to a less high-growth startup: a greater financing gap than for men(this gap is more apparent for high-growth firms), a lack of ideas, knowledge, and experience(related to the lack of mentorship), and lastly the difficulty maintaining a work-life balance. The findings are very similar with those found in studie's in the US(financing gap, work-life balance, and lack of mentorship). Further studies are required to identify more specific factors behind the gender gap in ideas, knowledge, and experience.