• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1613-1621
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• 2015

This paper analyzes the rate adaptation scheme and suggests applicable strategy of the MCS(Modulation and Coding Scheme) for improving DCF throughput in the IEEE 802.11ad and 802.11ad wireless LAN. IEEE 802.11ac and 802.11ad wireless LAN provide MCS technique that dynamically adjusts modulation level and code rate to the time-varying channel conditions in order to obtain considerably high data rates. But these standards did not provide rate adaptation algorithm, so this paper surveyes rate adaptation algorithm and suggests MCS scheme applied to IEEE 802.11ac and 802.11ad wireless LAN. Specially A MAC(Medium Access Control) layer throughput is evaluated over error-prone channel in the IEEE 802.11ac-based wireless LAN. In this evaluation, DCF (Distributed Coordination Function) protocol and A-MPDU (MAC Protocol Data Unit Aggregation) scheme are used. Using theoretical analysis method, the MAC saturation throughput is evaluated with the PER (Packet Error Rate) on the condition that the number of station, transmission probability, the number of parallel beams and the number of frames in each A-MPDU are variables.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11B
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• pp.1013-1019
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• 2008

Recently, various information and data are efficiently used by the rapid growth of its Internet in our real life. But, users have spent lots of time finding necessary information for the increased amounts of information. To solve this problem, it can be provided the speed, accuracy of information search with development of intelligent search engines, agent system etc. In this paper, we propose the method of getting the best tender price in the analysis of the construction bid information that needs its professionalism by on the purpose to maximize users' satisfaction. Of course, if it is not under the unit of a results in the future, we put target of this paper on part to heighten supreme successful bid success rate. Therefore, this paper embodies offered system of web based on producing tender price of most suitable through techniques to produce tender price about successful bid that compare with bidder fare by statistical analysis incidental and value approaching successful bidder fare by frequency analysis method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.420-426
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• 2018

Acoustic Quanta, which British Physicist Dennis Gabor created, is the theoretical background for granular synthesis and has influenced many computer music artists and sound designers. Acoustic Quanta is a very short sound burst, lasting only 1 to 100 ms. Granular synthesis is a sound synthesis technique which slices original sound into sound grains and re-combines them into a new acoustic event. Concept of sound grain is borrowed from the acoustic quanta. Granular Synthesis can make very unique sound, so that it can be useful in many ways, especially in sound design. This paper presents concept of acoustic quanta and granular synthesis. It then discusses making a synthesizer as an implementation of synchronous granular synthesis and its applications on sound design. As a result, the duration of acoustic quanta should range between 0.239 and 33.367 ms, in consideration of audible frequencies, which is different from the original concept of the acoustic quanta.

• The Journal of the Korea Contents Association
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• v.5 no.2
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• pp.187-197
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• 2005

In this paper, we propose an extended TB-tree, called ETB-tree, which can improve the performance of an existing TB-tree proposed for indexing the trajectories of moving objects in Location-Based Service(LBS). The proposed ETB-tree directly accesses the preceding node by maintaining a direct table, called D-Table which contains the page number in disk and memory pointers pointing the leaf node with the first and last lines segment of moving objects. It can improve the insertion performance by quick searching the preceding node of a moving object and retrieval performance owing to accessing directly the corresponding trajectories In disk for the trajectory-based query. In addition, the ETB-tree provides consistency of a tree by reflecting a newly inserted line segment to the tree both in memory and disk. The experimental results show that the proposed indexing technique gains better performance than other traditional ones with respect to the insertion and retrieval of a trajectory query.

• Journal of Biomedical Engineering Research
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• v.23 no.6
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• pp.419-430
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• 2002

In this paper. we propose an efficient method for implementing hi-directional pixel-based focusing(BiPBF) based on a sparse array imaging technique. The proposed method can improve spatial resolution and frame rate of ultrasound imaging with reduced hardware complexity by synthesizing transmit apertures with a small number of sparsely distributed subapertures. As the distance between adjacent subapertures increases, however. the image resolution tends to decrease due to the elevation of grating lobes. Such grating lobes can be eliminated in conventional synthetic aperture imaging techniques. On the contrary, grating lobes arisen from employing sparse synthetic transmit apertures can not be eliminated, which has been shown analytically in this paper. We also propose the condition and method for suppressing the grating lobes below -40dB, which is generally required in practical imaging. by placing the transmit focal depth at a near depth and properly selecting the subaperture distance in Proportion to receive aperture size. The results of both the Phantom and in vivo experiments show that the proposed method implements two-wav dynamic focusing using a smaller number of subapertures, resulting in reduced system complexity and increased frame rate.

• Journal of Broadcast Engineering
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• v.4 no.2
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• pp.144-154
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• 1999

The binomial sequences are family of orthogonal sequences that can be generated with remarkable simplicity-no multiplications are necessary. This paper introduces a class of non-recursive multidimensional filters for frequency-selective image processing without multiplication operations. The magnitude responses are narrow-band. approximately gaussian-shaped with center frequencies which can be positioned to yield low-pass. band-pass. or high-pass filtering. Algorithms for the efficient implementation of these filters in software or in hardware are described. Also. we show that the binomial QMFs are the maximally flat magnitude square Perfect Reconstruction paraunitary filters with good compression capability and these are shown to be wavelet filters as well. In wavelet transform the original image is decomposed at different scales using a pyramidal algorithm architecture. The decomposition is along the vertical and horizontal direction and maintains constant the number of pixels required to describe the images. An efficient perfect reconstruction binomial QMF-Wavelet signal decomposition structure is proposed. The technique provides a set of filter solutions with very good amplitude responses and band split. The proposed binomial QMF-filter structure is efficient, simple to implement on VLSl. and suitable for multi-resolution signal decomposition and coding applications.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.4
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• pp.395-404
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• 1999

포인터 스위즐링 기법은 포인터 스위즐링과 언스위즐링으로 이루어지며, 포인터 스위즐링은 객체 접근 시 객체 식별자를 해당 객체의 메모리 주소로 교체하는 것을 말하며, 언스위즐링은 객체 교체 또는 객체 저장 시에 스위즐링된 포인터를 원래의 객체 식별자로 환원하는 것을 말한다. 본 연구에서는 시스템 버퍼 구조에 따라 여러 포인터 스위즐링 기법을 분류하여 장단점을 분석하였으며, 이중 버퍼 구조 상에서 적극/소극, 직접/간접 스위즐링, 언스위즐링 모듈을 설계, 구현하였다. 또한 제한된 크기의 객체 버퍼 상에서 각 포인터 스위즐링 모듈의 성능을 평가하였다. 이 성능 평가의 결과로는 사용하지 않는 포인터는 스위즐링하지 않으며 언스위즐링 부담이 적은 소극 간접 스위즐링 기법이 일반적으로 뛰어난 성능을 나타냄을 알 수 있게 되었다.Abstract The pointer swizzling methods consist of pointer swizzling and unswizzling. Pointer swizzling replaces the OID of a object to the memory address of the object at object access time and unswizzling replaces the swizzling pointer of the OID at object replacement time or object save time. In this research, the different techniques for pointer swizzling are classified according to the system buffer structure and analyzed the pros and cons. In addition, eager/lazy, direct/indirect swizzling, unswizzling modules are designed and implemented on a dual buffering structure. Also, we evaluate the performance of pointer swizzling modules on the restricted object buffer size. The results of performance evaluation show that the performance of lazy indirect pointer swizzling technique is generally good because unused pointers are not swizzled, and unswizzling overhead is minimized.

• Journal of KIISE
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• v.43 no.2
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• pp.256-268
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• 2016

Modern networks consisting of various heterogeneous equipment are often installed in a distributed manner. Thus the NETCONF standard was established to manage networks centrally and efficiently. In this paper, we present a method that integrates each NETCONF layer into a single system based on the results of previous studies. In the RPC Layer, an asynchronous communication channel and parallel processes are possible using multi-threading. In the Operation Layer, operational efficiency is increased by using a data group with dependencies between the equipment configuration data and by improving the data structure, enabling efficiently processing of XML queries even with multiple managers. The data modeling techniques and grouping methods in the Content Layer are presented in detail for interoperability between the Operation Layer and the Content Layer. Finally, the GUI program was implemented and its implementation is reported. We performed an experiment comparing the improved NETCONF with the standard NETCONF to measure factors, such as query processing ratio, query processing speed, and CPU utilization. The improved NETCONF demonstrated excellent query processing ratio and query processing speed, whereas the standard NETCONF had excellent CPU utilization.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.5
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• pp.232-242
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• 2005

This paper concerns automatic hardware synthesis from data flow graph (DFG) specification for fast HW/SW cosynthesis. A node in BFG represents a coarse grain block such as FIR and DCT and a port in a block may consume multiple data samples per invocation, which distinguishes our approach from behavioral synthesis and complicates the problem. In the presented design methodology, a dataflow graph with specified algorithm can be mapped to various hardware structures according to the resource allocation and schedule information. This simplifies the management of the area/performance tradeoff in hardware design and widens the design space of hardware implementation of a dataflow graph compared with the previous approaches. Through experiments with some examples, the usefulness of the proposed technique is demonstrated.

• Journal of Korean Home Economics Education Association
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• v.1 no.1
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• pp.33-42
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• 1989

By the comparative analysis of high school Home Economics curricula in the U.S., Japan and Taiwan, this study first attempts to understand the current Home Economics education and to access its treads for each country. Based on the findings of the analysis, the study also seeks to get the major implications of the analysis for the betterment of the Korea Home Economics Education. The main sources of information and data analyzed here are： 1) curricula for both Oklahoma and Ohio state as representatives of the U.S.； 2) Home Economics Teaching Guidelines in Japan； and 3) Home Economics curriculum in Taiwan. Content Analysis technique is applied in this study. The major elements of contents include：1) structure of the curriculum； 2) subject name； 3) unit (time) allotment； 4) goals； 5) subject areas and content composition； and 6) other related characteristics for the implementation of the curriculum. Summarized results of the study outline as follows： 1) Home Economics is offered as independently required subject with equal status to Mathematics, Science, and Social Studies subject in all three countries； 2) Sex discrimination is prohibited both in the U.S. and Taiwan, while in Japan sex equity is not secured for Home Economics educations； 3) Time allotment for Home Economics in Japan and Taiwan is similiar to that in Korea；4) Subject areas cover such fields as Foods and Nutrition, Clothing and Textiles, Home Management, and Human Development in all three countries, which is similiar to those of Korea. In addition, Consumer Education and Career Education are also covered in the U.S., whereas in Japan Child Care is offered； and 5) Curriculum can be utilized as instructional planning material due to the clear specification of instructional methods, materials, and evaluation methods on the curriculum, especially in the U.S. and Taiwan.