• Journal of KIISE:Software and Applications
• /
• v.37 no.3
• /
• pp.214-221
• /
• 2010

The search-results clustering problem is defined as the automatic and on-line grouping of similar documents in search results returned from a search engine. In this paper, we propose a new search-results clustering algorithm specialized for a paper search service. Our system consists of two algorithmic phases: Category Hierarchy Generation System (CHGS) and Paper Clustering System (PCS). In CHGS, we first build up the category hierarchy, called the Field Thesaurus, for each research field using an existing research category hierarchy (KOSEF's research category hierarchy) and the keyword expansion of the field thesaurus by a word clustering method using the K-means algorithm. Then, in PCS, the proposed algorithm determines the category of each paper using top-down and bottom-up methods. The proposed system can be used in the application areas for retrieval services in a specialized field such as a paper search service.

• Journal of the Korean School Mathematics Society
• /
• v.16 no.3
• /
• pp.499-518
• /
• 2013

The purpose of this study is to examine the preservice secondary mathematics teachers understanding and dimensions of knowledge about definition of irrational numbers and irrational numbers and operations. I adopted a framework consisting of formal dimensions, intuitive numbers, algorithmic dimentions suggested by Tirosh et al.(1998) by adding instrumental dimension for his study. I surveyed 65 preservice secondary mathematics teachers who are in bachelor program and post-bachelor program for teacher certificate by using a questionnaire suggested by Sirotic and Zazkis(2007). The results of this study suggest that 83.1% of the participants gave correct answers in definitions of irrational numbers. 43% of the preservice secondary teachers gave correct answers in adding with irrational numbers. Also 91% of the preservice teachers gave correct answers in multiplying irrational numbers. The preservice teachers appeared to understand irrational numbers and operations at formal dimension. More than half of the preservice teachers gave incorrect answers in adding irrational numbers and a few participants gave incorrect in multiplying irrational numbers. The preservice teachers seemed to understand irrational numbers and operations at intuitive or instrumental dimension. The results also suggest that the preservice secondary mathematics teachers have incorrect understanding about irrational numbers.

• Journal of The Korean Association of Information Education
• /
• v.11 no.1
• /
• pp.29-38
• /
• 2007

Computer programming in computer education draws much attention recently. Encouraged by the increased tendency of acquiring logical ability and creativity through learning, various attempts have been made to develop them through learning computer programming in the area of computer education as well. The fact that a computer program is the representation of a computer algorithm expressed in a computer language makes us realize that the devise of a logical method for a solution - i.e., the design of an algorithm - is the key to the solution of a problem. Recognizing the importance of computer algorithm would lead us to such a point that systematic investigations for directional establishment for algorithm education are necessary. We observe that researches on teaching computer algorithm have concentrated mostly on specific problems such as sorting and searching, which can be characterized as problem-dependent and individual. In this paper, the idea of conceptual algorithm is stated from the standpoint of conceptual types of problem-solving methods which are considered as problem-independent and collective. A novice approach to algorithm education based on the characteristics of types of conceptual algorithms is proposed for the purpose of developing systematic, problem-independent, algorithmic problem-solving capabilities of learners, which is widely different from the current methods of individual and problem-dependent algorithm education.

• Journal of The Korean Association of Information Education
• /
• v.12 no.3
• /
• pp.303-312
• /
• 2008

In correspondence to the educational demand on study of computer principles that is recently being focused, this study promotes basic understanding on data structure and algorithm at the elementary student level through the process of simple numerical expressions and proposes effective education contents and methods. For this, an unplugged type computer education material was produced to understand the method of the computers for receiving data through activities. Also, we proposed students to create animation data to learn numerical expressions and algorithm through arrangements and linked lists. To examine educational effectiveness of this study, an experiment study was conducted through the education content and method to the subject of one class in the fifth-grade of elementary school located in OO metropolitan city. As a result, the student learned that there is a difference in calculation method between computers and people; and this enabled basic understanding on algorithm and data structure and presented positive responses to algorithm and data structure. In conclusion, it is confirmed that it is possible to provide effective education for students if the principle study of algorithm is proposed to proper levels.

• The Journal of the Acoustical Society of Korea
• /
• v.18 no.7
• /
• pp.33-38
• /
• 1999

In this paper, we combine a generalized analysis-by-synthesis (AbS) structure and an algebraic excitation scheme to propose a new 4kb/s speech codec. This codec partly uses the structure of G.729. We design a line spectrum pair (LSP) quantizer, an adaptive codebook, and an excitation codebook to fit the 4 kb/s bit rate. The codec has a 25㎳ algorithmic delay, which corresponds to a 20㎳ frame size and a 5㎳ lookahead. At the bit rates below 4kb/s, most CELP speech codecs using the AbS principle have a drawback that results a rapid degradation of speech quality. To overcome this drawback we use the generalized AbS structure which is efficient for the low bit rate speech codec. LP coefficients are converted to LSP and quantized using a predictive 2-stage VQ. A low complexity algebraic codebook which uses shifting method is used for the fixed codebook excitation, and gains of the adaptive codebook and the fixed codebook are quantized using the VQ. To evaluate the performance of the proposed codec A-B preference tests are done with the fixed rate 8kb/s QCELP. As the result of the test, the performance of the codec is similar to that of the fixed rate 8kb/s QCELP.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.8 no.3
• /
• pp.84-95
• /
• 2005

This paper presents solution heuristics to solving optimal multiple-viewpoint location problems that are based on topographic features. The visibility problem is to maximise the viewshed area for a set of viewpoints on digital elevation models (DEM). For this analysis, five areas are selected, and fundamental topographic features (peak, pass, and pit) are extracted from the DEMs of the study areas. To solve the visibility problem, at first, solution approaches based on the characteristics of the topographic features are explored, and then, a benchmark test is undertaken that solution performances of the solution methods, such as computing times, and visible area sizes, are compared with the performances of traditional spatial heuristics. The feasibility of the solution methods, then, are discussed with the benchmark test results. From the analysis, this paper can conclude that fundamental topographic features based solution methods suggest a new sight of visibility analysis approach which did not discuss in traditional algorithmic approaches. Finally, further research avenues are suggested such as exploring more sophisticated selection process of topographic features related to visibility analysis, exploiting systematic methods to extract topographic features, and robust spatial analytical techniques and optimization techniques that enable to use the topographic features effectively.

• KIISE Transactions on Computing Practices
• /
• v.24 no.1
• /
• pp.40-45
• /
• 2018

With the advent of big data and social networks, large-scale graph processing becomes popular research topic. Recently, an optimization technique called Gorder has been proposed to improve the performance of in-memory graph processing. This technique improves performance by optimizing the graph layout on memory to have better cache locality. However, since it is designed for in-memory graph processing systems, the technique is not suitable for disk-based graph engines; also the cost for applying the technique is significantly high. To solve the problem, we propose a new graph ordering called I/O Order. I/O Order considers the characteristics of I/O accesses for SSDs and HDDs to improve the performance of disk-based graph engine. In addition, the algorithmic complexity of I/O Order is simple compared to Gorder, hence it is cheaper to apply I/O Ordering. I/O order reduces the cost of pre-processing up to 9.6 times compared to that of Gorder's, still its performance is 2 times higher compared to the Random in low-locality graph algorithms.

• 한국HCI학회:학술대회논문집
• /
• 2008.02a
• /
• pp.733-738
• /
• 2008

Serial Music, introduced by A. Sch nberg, is a one of the important composition techniques. This music style has features of pantonality and atonality, so it generates unique atmosphere of modern music. In this paper, we introduce an method of generating serial music using mathematical algorithm. This method generates music that satisfy the requirement that the number of pitches belonged to each pitch class are exactly same, though the requirement is less strict than Sch nberg's definition. To do this, our method uses space-filling curves traversing the twelve tone matrix, which is constructed by the serial series, its inversion and its transpose. Using these curves, we can generate a music that has all notes in the matrix exactly once and adequate repeatness because of the curve's locality. Result music, therefore, can be more suitable for people that are not familiar with modern music, while maintaining the features of pantonality and atonality. This paper also introduces a method of generating extended serial music that uses serialism of duration and dynamic of notes, using multi-dimensional space-filling curves.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.12
• /
• pp.1079-1085
• /
• 2013

Due to the limited power supply resources, it is essential that the minimization of algorithmic operation and the reduction of the hardware logical-resources in the design of the satellite transponder. It is also required that the transponder process the signals of various bandwidth efficiently, that is suitble for the SDR-based implementation. This paper proposes a variable rate down sampler which can provide variable bandwidth and data rate for carrier, ranging and sub-band command signals respectively. The proposed down sampler can provide multiple $2^M$ decimated outputs from a single half band filter with recursive arithmetic architecture, which can minimize the hardware resources as well as the arithmetic operations. The algorithm for hardware implementation as well as the analysis for the passband flatness and aliasing is presented and varified by the FPGA implementation.

• The KIPS Transactions:PartA
• /
• v.12A no.3 s.93
• /
• pp.243-252
• /
• 2005

This paper introduces a noble modeling technique to build data communication prediction models in multiprocessors, using Least-Squares and Robust Estimation methods. A set of sample communication rates are collected by using a few small input data sets into workload programs. By applying estimation methods to these samples, we can build analytic models that precisely estimate communication rates for huge input data sets. The primary advantage is that, since the models depend only on data set size not on the specifications of target systems or workloads, they can be utilized to various systems and applications. In addition, the fact that the algorithmic behavioral characteristics of workloads are reflected into the models entitles them to model diverse other performance metrics. In this paper, we built models for cache miss rates which are the main causes of data communication in shared memory multiprocessor systems. The results present excellent prediction error rates; below $1\%$ for five cases out of 12, and about $3\%$ for the rest cases.