• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.690-692
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• 2014

To identify characterization of a simple extension chamber that have the two internal partition, produce the curve to estimate the transmission loss without the computer analysis. For helpful for internal optimum design, identify the characteristic of internal partition on transmission loss. Made estimated transmission loss curve by function of relationship of internal partition and transmission. Check the similarity of predicted transmission loss and analysis transmission loss. Usage of the predicted transmission loss made by relationship of internal partition and transmission loss is good information to place the internal partition so as to maximize the transmission loss on target frequency at optimal design on muffler.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.8
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• pp.1876-1889
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• 2013

Packet-based mobile multimedia services for the Internet differ with respect to their resource requirements, performance objectives, and resource usage efficiencies. Nonetheless, each mobile terminal should support a variety of multimedia services, sometimes even simultaneously. This paper proposes a sub-channel allocation scheme based on multi-level priority for supporting mobile multimedia services in an Orthogonal Frequency Division Multiple Access (OFDMA) system. We attempt to optimize the system for satisfying the Quality of Service (QoS) requirements of users and maximize the capacity of the system at the same time. In order to achieve this goal, the proposed scheme considers the Signal-to-Interference-plus-Noise Ratio (SINR) of co-sub-channels in adjacent cells, the Signal-to-Noise Ratio (SNR) grade of each sub-channel in the local cell on a per-user basis, and the characteristics of the individual services before allocating sub-channels. We used a simulation to evaluate our scheme with the performance measure of the outage probabilities, delays, and throughput.

• Management & Information Systems Review
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• v.3
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• pp.439-460
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• 1999

The purpose of this paper is to compare the characteristics between group that has only one credit card and group that has multiple credit cards in each stage of purchase decision making based on the literature in consumer behavior. Results indicated that (1) The number of credit cards that consumers has was affected by internal factor and reference factor, (2) depending on the number of credit cards, usage frequency, amount, and duration were differently showed and (3) inertia, point accumulation, and convenience were founded as determinants of using credit cards. Finally, theoretical and managerial implications of these findings are discussed.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.366-371
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• 2012

In this paper, we propose an electric circuit using one common-arm of H-Bridge inverters to reduce the number of switching components in the multi-level inverter combined with H-Bridge inverters and transformers. And furthermore, we suggested a new multi-level PWM inverter using PWM level to reduce THD (Total Harmonic Distortion). We use a phase-shift switching method that has the same rate of usage at each transformer. Also, we test the proposed prototype 9-level inverter to clarify the proposed electric circuit and reasonableness of the control signal for the proposed multi-level PWM inverter.

• International Commerce and Information Review
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• v.6 no.2
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• pp.171-191
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• 2004

Recently, RFID(Radio Frequency IDentification) is observed with government and connection enterprises as the central figure. RFID utilizing radio is a technology that enable exchange of information sensing and recognize object. RFID is expected that the practical use limits widens by territory that can form vast market such as logistics management according to RFID's low-cost aggravation as well as usage of life and improvement of performance because present R&D is gone vigorously. Because RFID is possible application everywhere if it is various service industries as well as logistics, industry spot, manufactory and place that flowing of goods is, is used, and is becoming big limelight from society several territories.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.123-124
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• 2006

This paper investigates an efficient pre-equalization technique that can be applied on the up-link of a time division duplex (TDD) orthogonal frequency division multiplexing (OFDM) systems. This technique provides the spectral efficiency by omitting the usage of training sequences on the up-link. In this paper, the performance of a variety of pre-equalization techniques is analyzed and simulations are performed by applying power efficient pre-equalization algorithms with phase and amplitude & phase pre-equalization in the Rayleigh fading channel.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.3
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• pp.135-141
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• 2014

The inherent feature of the highly efficient spectrum usage has made Orthogonal Frequency Division Multiplexing (OFDM) preferable for Communication Standards. This study evaluated the performance of a Least Square (LS) estimator for a comb-type pilot insertion scheme over a fast fading Rayleigh channel. A High Peak-to-Average Power Ratio (PAPR) is one of the major downsides of the OFDM. The effects of an increase in the number of subcarriers on PAPR and the performance of the LS Estimator were studied. Increasing the number of subcarriers while keeping the pilots overhead constant resulted in improved performance of the LS estimator but the PAPR increased with increasing number of subcarriers. Therefore some trade-off between the number of subcarriers and the performance of the OFDM system is needed. The Mean Square Error (MSE) expression was also derived for the LS estimator in the case of a comb-type pilot arrangement. The MSE expression clearly explains the effects of the number of subcarriers on the performance of the LS estimator.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.339-342
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• 2000

This paper presented a FPGA design of SEED, which is the Korea standard 128-bit block cipher. In this work, SEED was designed technology- independently for other applications such as ASIC or core-based designs. Hence in case of changing the target of design, it is not necessary to modify design or need only minor modification to reuse the design. Since SEED algorithm requires a lot of hardware resources, each unit was designed only once and used sequentially. So, the number of gates was minimized and SEED algorithm was fitted in FPGA without additional components. It was confirmed that the rate of resource usage is about 80% in ALTERA 10KE and the SEED design operates in a clock frequency of 131.57 MHz and an encryption rate of 29 Mbps.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.673-676
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• 2005

In this paper, we proposed the electric circuit using one common arm of H-Bridge Inverters to reduce the number of switching component in multi-level inverter combined with H-Bridge Inverters and Transformers. and furthermore we suggested the new multi-level PWM inverter using PWM level to reduce THD(Total Harmonic Distortion). and we used the switching method that can be same rate of usage at each transformer. Also, we tested the proposed prototype 9-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi-level PWM inverter.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.949-952
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• 2000

공유 저장장치에 접근할 수 있는 경로를 다중화함으로써 클러스터 파일시스템 내 한 노드에서 발생하는 결함을 허용할 수 있다. 공유 저장장치의 다중접근은 파일 이동과 파일 중복으로 이루어진다. 본 논문에서는 전역 파일 시스템의 평균 응답 시간을 줄이기 위해 파일 자원의 접근률에 따라 우선 순위를 두어 파일이동과 과일 중복 시 발생할 수 있는 클러스터 파일 시스템의 성능 저하 및 서비스 중단을 막기 위한 방법을 제안한다. 파일 자원의 접근률은 파일 처리 시에 사용되는 블록, 아이노드(mode), 슈퍼블록과 같은 자원 사용 빈도를 통해 얻어질 수 있다.