• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.106-113
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• 2003

Smart UAV Development Program, one of the 21c Frontier R&D Program sponsored by MOST(Ministry of Science and Technology), was launched in 2002. As an air vehicle for the Smart UAV, CRW(Canard Rotor/Wing) concept was one of the candidates compared in trade-off study. The CRW concept has not only been proven completely but its aerodynamic characteristics not known in detail yet. Two calculation methods were adopted in this study to obtain aerodynamic data for the CRW. First method was the superpose DATCOM method which is capable of three lifting surfaces, and second one is the full Navier-Stokes computation around CRW configuration using overset grid method. Basic aerodynamic characteristics of the CRW configuration was analyzed and the minimum drag level with lift to drag ratio is presented. The peculiar flow characteristics around rotor/wing and hub were also examined and considered in the configuration design.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.319-322
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• 2002

In this paper, we consider a generalized rule of retransmission request, identified as (Μ, $\sigma$) rule for multicopy transmission ARQ. Following a revised rule to conform with a strict criterion for requesting a retransmission, we can reduce the probability that a packet accepted by the receiving node is still being infected with errors. In turn, such amendment invokes a degradation of delay and throughput performance. For a quantitative evaluation of (Μ, $\sigma$) rule, we develop an analytical method to calculate probability of error remains, maximum throughput, average and peak delays, and delay variation. From the numerical examples made by use of the analytical method, we observe a performance trade-off between probability of error remains and delay/throughput. We also confirm the adaptability of (Μ, $\sigma$) rule to meet various QoS requirements.

• Journal of the Korean Home Economics Association
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• v.38 no.12
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• pp.1-14
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• 2000

The purpose of this study is to identify the change according to income bracket and the trade-off between expenditure items by analyzing expenditure patterns of the urban households as a reset of the IMF. The results of this study are as follows; The composition percentage and the amount of consumption expenditure of urban households after IMF decrease in all classes. But the change of composition percentage by the decrease of consumption expenditure is different in every class. The percentage of decrease of the upper class is higher than that of the lower class in an essential expenditure of household, which is food. And the percentage of decrease of the lower class is higher than that of the higher class in the discretionary expenditures such as clothes and education.

• Journal of Korean Institute of Industrial Engineers
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• v.18 no.2
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• pp.23-29
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• 1992

To compute the expected travel time of storage and retrieval (S/R) machine in automated warehousing systems most of the previous studies assumed that equal number of rack openings are required regardless of the nature of storage assignment rules. It is known that randomized storage assignment rule usually needs less storage to space than needed for full turnover-based assignment rule. The objective of this paper is compute the expected travel time of each assignment rule more equitably by taking into account the storage space required for each rule. First, the rack storage space is determined which satisfies a given service level. Then based on the standard Economic Ordering Quantity model, trade-off analysis is carried out which relates the storage space to the expected travel time of the S/R machine. Finally, example problems are solved to compare the performance of each assignment rule under varying conditions of demand pattern and service level.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.154-160
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• 2007

A direction finding system test-bed(DFSTB) at the electronic warfare communication-band is presented to efficiently evaluate and optimize the performance of the direction finding system through the indoor test setup. This test-bed gives a significant benefit to the designers of the direction finding system because it allows flexible test and design trade-off in the system design cycle. The system description and implementation of test-bed architecture, and the experiment results of direction finding accuracy according to modulation schemes are presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1540-1547
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• 2000

In this paper, the performance of the MMSE multiuser detector is compared with the conventional detector with respect to the signal-to-noise ratio, the number of users and the Nakagami parameter under AWGN as well as Nakagami fading channel. The results show that the MMSE multiuser detector is superior to the conventional detector with respect to cancelling the multiple access interference. However, its drawback is the hardware's complexity. To solve this drawback, the advanced MMSE multiuser detector is presented, and its performance is analyzed. The number of taps in the advanced MMSE multiuser are independent of the processing gain. Thus, the system engineer can choose the appropriate number of taps in the detector to achieve a optimal trade-off between the hardware complexity and the performance of system.

• Annual Conference of KIPS
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• 2019.10a
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• pp.60-62
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• 2019

지능형 IoT 애플리케이션들을 효과적으로 사용하기 위해서는 추론 엔진을 Edge device로 포팅하는 것이 필수적이다. 그러나 컴퓨팅 자원이 제한적인 Edge 환경에서 computational cost가 상당히 큰 CNN 추론을 실시간으로 하는 것은 쉽지 않다. 이에, CNN 추론의 하드웨어 가속화의 필요성이 제기되어 활발한 연구가 진행되고 있으며, Xilinx, Intel 등에서도 하드웨어 가속화를 도와주는 툴을 개발하여 지속적으로 업그레이드하고 있다. 본 연구에서는 CIFAR-10 데이터베이스의 테스트 이미지 10,000개를 Xilinx 사의 CNN 추론 엔진인 DPU를 사용하여 Zynq UltraScale+ 보드에서 추론해보고, DPU 아키텍처에 따른 결과를 비교·분석했다. 병렬처리 수준을 높게 한 DPU는 그렇지 않은 DPU보다 소비전력 및 자원 사용량이 3배 이상 높았지만, 1.65배 좋은 성능을 보여 Trade-off 관계를 확인할 수 있었다.

• IEMEK Journal of Embedded Systems and Applications
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• v.16 no.5
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• pp.233-240
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• 2021

We propose a novel, highly accurate approximate multiplier using different types of inexact 4-2 compressors. The importance of low hardware costs leads us to develop approximate multiplication for error-resilient applications. Several rules are developed when selecting a topology for designing the proposed multiplier. Our highly accurate multiplier design considers the different error characteristics of adopted compressors, which achieves a good error distribution, including a low relative error of 0.02% in the 8-bit multiplication. Our analysis shows that the proposed multiplier significantly reduces power consumption and area by 45% and 26%, compared with the exact multiplier. Notably, a trade-off relationship between error characteristics and hardware costs can be achieved when considering those of existing highly accurate approximate multipliers. In the image blending, edge detection and image sharpening applications, the proposed 8-bit approximate multiplier shows better performance in terms of image quality metrics compared with other highly accurate approximate multipliers.

• Journal of Korea Planning Association
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• v.53 no.7
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• pp.67-86
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• 2018

This paper attempted to analyze impacts of transition in electricity generation system on a national economy and environmental level in Korea using a recursive computable general equilibrium(CGE) model. In particular, the paper presented a hybrid model combining the top-down CGE model with the bottom-up model which describes the structure of electricity production in detail. The impacts were analyzed by two policy scenarios base on the basic plan for electricity supply and demand proposed by the Korean government. As a result, the paper specifically showed that there exists a trade-off relationship in the policy-making between economic efficiency and environmental level. The paper also suggested that the transition in electricity generation system should be done more gradually and carefully.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.236-238
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• 2019

본 논문에서는 반도체 세정용 플라즈마 발생장치의 인버터 구성에 따른 손실을 비교 및 분석한다. 플라즈마를 유지하기 위해 DC-AC 인버터는 고전압을 출력해야 한다. 따라서 고효율 동작을 위해 각 인버터 구성에 따른 trade-off를 고려한 회로 선정이 필요하다. 이를 위해 20 kW 급 시뮬레이션을 수행하고 이를 토대로 전력 반도체 소자 및 자성체에서 발생하는 손실, 부피, 가격 등 각 인버터 구성에 따른 장단점 분석을 진행한다. 또한 분석 결과를 통해 플라즈마 발생자치에 적합한 인버터 구성 방식을 제시한다.