• Journal of KIISE:Computer Systems and Theory
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• v.37 no.2
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• pp.66-75
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• 2010

This paper proposes an efficient method for design and implementation of the artificial intelligence (AI) of 'omok' game on the GPU. The proposed AI is designed on a cooperative structure using min-max game tree and genetic algorithm. Since the evaluation function needs intensive computation but is independently performed on a lot of candidates in the solution space, it is computed on the GPU in a massive parallel way. The implementation on NVIDIA CUDA and the experimental results show that it outperforms significantly over the CPU, in which parallel game tree and genetic algorithm on the GPU runs more than 400 times and 300 times faster than on the CPU. In the proposed cooperative AI, selective search using genetic algorithm is performed subsequently after the full search using game tree to search the solution space more efficiently as well as to avoid the thread overflow. Experimental results show that the proposed algorithm enhances the AI significantly and makes it run within the time limit given by the game's rule.

• The Journal of the Korea Contents Association
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• v.11 no.2
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• pp.126-134
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• 2011

Recently, many researchers are interested in using join queries to correlate sensor readings stored in different regions. In the conventional algorithm, the preliminary join coordinator collects the synopsis from sensor nodes and determines a set of sensor readings that are required for processing the join query. Then, the base station collects only a part of sensor readings instead of whole readings and performs the final join process. However, it has a problem that incurs communication overhead for processing the preliminary join. In this paper, we propose a novel energy-efficient in-network join scheme that solves such a problem. The proposed scheme determines a preliminary join coordinator located to minimize the communication cost for the preliminary join. The coordinator prunes data that do not contribute to the join result and performs the compression of sensor readings in the early stage of the join processing. Therefore, the base station just collects a part of compressed sensor readings with the decompression table and determines the join result from them. In the result, the proposed scheme reduces communication costs for the preliminary join processing and prolongs the network lifetime.

• Journal of KIISE
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• v.44 no.11
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• pp.1138-1148
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• 2017

Topic extraction is a technology that automatically extracts a set of topics from a set of documents, and this has been a major research topic in the area of natural language processing. Representative topic extraction methods include Latent Dirichlet Allocation (LDA) and word clustering-based methods. However, there are problems with these methods, such as repeated topics and mixed topics. The problem of repeated topics is one in which a specific topic is extracted as several topics, while the problem of mixed topic is one in which several topics are mixed in a single extracted topic. To solve these problems, this study proposes a method to extract topics using an LDA that is robust against the problem of repeated topic, going through the steps of separating and merging the topics using the similarity between words to correct the extracted topics. As a result of the experiment, the proposed method showed better performance than the conventional LDA method.

• The KIPS Transactions:PartB
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• v.16B no.4
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• pp.289-298
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• 2009

Active Contour Model, that is, Snake algorithm is effective for detection and tracking the objects. However, this algorithm has some drawbacks; numerous parameters must be designed(weighting factors, iteration steps, etc.), a reasonable initialization must be available and moreover suffers from numerical instability. Therefore we propose a novel Energy Corrected Snake(ECS) algorithm which improved on external energy of Snake algorithm for detection and tracking the moving object more effectively. The proposed algorithm uses the difference image, getting when the object is moving. It copies four direction images from the difference image and performs the accumulating compute to erasing image noise, so that it gets external energy steadily. Then external energy united with contour that is computed by internal energy. Consequently we can detect and track the moving object more speedily and easily. To show the effectiveness of the proposed algorithm, we experiment on 3 situations. The experimental results showed that the proposed algorithm outperformed by 6$\sim$9% of detection rate and 6$\sim$11% of tracker detection rate compared with the Snake algorithm.

• Journal of KIISE:Software and Applications
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• v.28 no.9
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• pp.662-668
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• 2001

Since the problem of disproving a tautology is as hard as the problem of proving it, no polynomial time algorithm for falsification(or testing invalidity) is feasible. Previous algorithms are mostly based on either divide-and-conquer or graph representation. Most of them demonstrated satisfactory results on a variety of input under certain constraints. However, they have experienced difficulties dealing with big input. We propose a new falsification algorithm using a Merge Rule to produce a counterexample by constructing a minterm which is not satisfied by an input expression in DNF(Disjunctive Normal Form). We also show that the algorithm is consistent and sound. The algorithm is based on a greedy method which would seek to maximize the number or terms falsified by the assignment made at each step of the falsification process. Empirical results show practical performance on big input to falsify randomized nontautological problem instances, consuming O(nm$^2$) time, where n is the number of variables and m is number of terms.

• The Journal of Engineering Geology
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• v.32 no.3
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• pp.339-350
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• 2022

There are a variety of types in tafoni formed in Miocene tuff from Golgulsa, Gyeongju. Tuff bearing tafoni was quite weathered, composed of quartz, feldspars, micas, vermiculite, chlorite, smectite, and analcite. In the early stage of the tafoni development, tafoni preferentially formed from cavities where volcanic breccias were removed or from microcavities where microcrystals were chemically altered. Small tafoni grew into large one by merging each other. The orientation of tafoni is inversely arranged to slopes, with slight inclination toward the inner cavity. Height, width, and depth of tafoni are closely interrelated: the correlation coefficients are 0.839 (width-height), 0.900 (width-depth), and 0.856 (height-depth), respectively. Removal of walls between tafoni resulted in lenticular or crescent forms, and small tafoni laterally combined to large tafoni. Large tafoni is weak because of high porosity and low strength compared to normal slope. Therefore, systematic monitoring for slope strength, pore proportion and volume, and growth of cavity needs to secure the slope stability where tafoni in Golgulsa is widespread.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.531-538
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• 2023

Recently, many university classes have been changing from instructor-centered classes to learner-centered classes, and universities are trying to establish a new direction for university education, especially to foster talented people suitable for the Fourth Industrial Revolution. To this end, universities are presenting various competencies necessary for students and focusing on research on efficient education plans for each competency. Among them, creativity is considered the most important competency that students should obtain in universities. Developing a creative problem-solving-based subject where various majors gather to produce results while conducting creative team activities away from desk classes is considered a meaningful subject to cultivate capacities suitable for the requirements of the times. Therefore, this study purpose to develop creative problem-solving-based subjects and analyze the results of class progress. This creative problem-solving-based class is an Action Learning class for step-by-step idea development, which starts with a theoretical lecture for creative idea development and then consists of five stages of Action Learning. The tasks of action learning used in this class consisted of ceramic expression to increase the intimacy of the formed group and the group's collective expression, ideas in life to combine and compress individual ideas into one, environmental improvement programs around schools, and finally UCC on various topics. In the theoretical lecture conducted throughout the class, a class was conducted on Scientific Thinking for creative problem solving, and then a group-type action learning class was conducted sequentially. This Action Learnin process gradually increased the difficulty level and led to in-depth learning by increasing the level of difficulty step by step.

• Journal of Technology Innovation
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• v.31 no.3
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• pp.139-169
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• 2023

This study analyzes the effects of firms' technology innovation(patent applications) on employment(number of workers and proportion of high-skilled workers) and corporate performance(sales per worker), while considering the two-way causal relationships between these variables. We used the three-stage least squares(3SLS) estimation to examine system of equations in which the dependent variables affect each other with a two-year lag wherever relevant, and applied it to firm-level panel data of Korean manufacturers with 100 or more workers. Our data covered the period of 2005-2017. Exogenous variables, such as firms' managerial and other characteristics, were controlled as explanatory variables. The identification variables for each equation included firms' R&D intensity, labor cost per worker(or operation of firms' own R&D center), and investment on worker training. We find that firms' patent applications increased number of workers, proportion of high-skilled workers, and sales per worker; the causal relationships in the opposite direction were also significant. Evidently, firms' technology innovation is critical to the growth and quality improvement of employment as well as sustainable corporate growth.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.277-288
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• 2005

Perlite, a hydrated volcanic glass, occurs mainly as a bed-like body, and is distributed intermittently along the unconformity surface between the Beomgockri Group and its lower formations, viz. Janggi Group. The perlite is intimately associated with surrounding pumiceous welded tuff and rhyodacites in space and time. Compared to the typical perlite, the perlite is rather silica-poor and impure, and thus, includes lots of phenocrysts and rock fragments. Nearly the perlite is compositionally rather close to a pitchstone than a perlite in water contents. Petrographic comparison between perlite and associated volcanic to volcaniclastic rocks indicates that pumiceous welded tuff and rhyodacite seem to be Protolith of the Perlite. A Zr/$TiO_{2}$-Nb/Y diagram and field occurrence of perlite and their protolithic rocks also conforms the above interpretation. Kn addition, remnant vesicles in perlite strongly reflect that the precursor of perlitic glass appeared to be pumice fragment as well as volcanic glass. The perlite was diagenetically formed by way of a pervasive water-rock interaction at the deposition of the Manghaesan Formation in lacustrine environment. During perlitization, $SiO_{2}$ and alkali tend to be consistently depleted. Preexisting system of the Beomgockri Group based on the perlite formation should be corrected, because the perlite was formed diagenetically without lateral persistence in its occurrence.

• Clinical and Experimental Pediatrics
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• v.53 no.2
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• pp.184-189
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• 2010

Purpose : Pseudomembranous colitis (PMC) occurs rarely in children, but its incidences are increasing due to frequent antibiotic use. We investigated the incidence and clinical characteristics of PMC accompanied by bacterial enteritis-like symptoms in children. Methods : Between November 2003 and July 2007 at the Department of Pediatrics, Dongsan Medical Center, we analyzed the medical records of consecutive patients who received antibiotics in the past 1 month, developed bacterial enteritis-like symptoms, and were diagnosed with PMC based on sigmoidoscopy examination and histological findings. Results : Among 22 patients who underwent sigmoidoscopy and biopsy examinations, 11 (50%) were diagnosed with PMC. These 11 patients were aged 2 months-12 years, among whom 5 patients (45.5%) were less than 1 year old. The clinical symptoms were bloody diarrhea (28.6%), abdominal pain or colic (28.6%), watery or mucoid diarrhea (23.8%), vomiting (9.5%), and fever (9.5%). The antibiotics used were penicillins (55.6%), macrolides (27.8%), cephalosporins (11.1%), and aminoglycosides (5.6%). The period of antibiotic use was 3-14 days. The interval between the initial antibiotic exposure and the onset of symptoms was 5-21 days. The results of stool examination of all patients were negative for Clostridium difficile toxin A. Patient distribution according to the degree of PMC was as follows: grade I, 18.2% (2 cases); grade II, 27.3% (3); grade III, 36.4% (4); and grade IV, 18.2% (2). PMC did not recur in any case.Conclusion : PMC is not a rare disease in children. If pediatric patients receiving antibiotics manifest symptoms like bacterial enteritis, PMC should be suspected. Endoscopy and biopsy should be applied as aggressive diagnostic approaches to detect this condition.