• 제목/요약/키워드: performance point

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MIMO 시스템을 위한 Out-of-Constellation Point 보정 Lattice Reduction-aided 검출기법 (Lattice Reduction-aided Detection with Out-of-Constellation Point Correction for MIMO Systems)

  • 최권휴
    • 한국통신학회논문지
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    • 제32권12A호
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    • pp.1339-1345
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    • 2007
  • MIMO 시스템을 위한 Lattice Reduction (LR) aided 검출 방법의 중요한 단점의 해결책으로 심별 판별의 신뢰도가 의심되는 경우 추가적인 보정을 해주면서, 계산양은 매우 작은 개선된 LR-aided 검출방법을 제안한다. LR 검출방법의 오류들은 주로, 마지막 lattice 역 변환 단계에서, lattice point들이 constellation point 바깥으로 벗어날 때 발생한다는 것을 발견하였다. 이를 기반으로, 제안된 기법에서는 LR-aided 검출방법을 통해 얻어진 lattice point들이 constellation 바깥쪽에 있는지를 확인하고, 바깥쪽에 있는 경우, 모든 constellation point들이 아닌, 얻어진 lattice point의 이웃하는 point들에 대해서만 ML(Maximum Likelihood) 검출을 수행한다. 제안된 기법을 사용함으로, 검출 성능은 ML에 근접하면서, 계산양은 아주 작은 효과를 기대할 수 있다.

IEEE 802.16e OFDMA TDD 시스템 하향링크 트래픽 채널의 Fixed-point 구현 방법론 (Fixed-point Implementation for Downlink Traffic Channel of IEEE 802.16e OFDMA TDD System)

  • 김규현;선태형;왕우붕;장경희;박형일;어익수
    • 한국통신학회논문지
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    • 제31권6A호
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    • pp.593-602
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    • 2006
  • 본 논문에서는 IEEE 802.16e에 기반한 OFDMA TDD 시스템 하향 링크 트래픽 채널의 fixed-point 구현을 위해 Floating-point 모델로부터 성능 열화와 하드웨어 복잡도를 최소화 할 수 있도록 적절한 비트 사이즈를 결정하는 방법론에 대하여 기술한다. Fixed-point 구현에 있어서 여러 가지 고려 사항 중 하나는 비트 사이즈를 절사하는 방법에 따른 Saturation과 Quantization의 선택이며, 반드시 주의해야 할 점은 신호의 분포를 정확히 파악한 후 신호의 분포에 맞도록 Saturation과 Quantization 중 하나의 비트 절사방법을 적절히 적용시켜야 한다는 점이다. 또한, 시행착오를 거치면서 여러 비트 사이즈에 대하여 모의 실험을 수행하여야만 성능 열화를 최소화 하면서 원하는 비트 사이즈를 얻을 수 있다. 본 논문에서는 수신단의 트래픽 채널에 최적화된 비트 사이즈를 결정하기 위하여 AWGN 및 ITU-R M.1225의 Veh-A 채널 환경에서 컴퓨터 모의 실험을 수행한다.

고성능 512-point FFT 프로세서의 설계 (A Design of High Throughput 512-point FFT Processor)

  • 김선호;김정우;오길남;김기철
    • 한국방송∙미디어공학회:학술대회논문집
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    • 한국방송공학회 1999년도 학술대회
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    • pp.255-260
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    • 1999
  • 본 논문에서는 데이터 입출력을 고속으로 수행하며 작은 지연시간을 갖는 512-point FFT프로세서의 구조및 설계에 대하여 보인다. 설계된 512-point FFT프로세서는 OFDM방송에서 요구하는 심볼 레이트로 테이타를 처리할 수 있는 것을 목표로 하였다. 설계된 512-point FFT프로세서는 써플메모리를 이용하여 메모리의 요구사항을 최소화하며, 새로운 strength reduction method를 적용한 복소곱셈기를 이용하여 기존의 복소곱셈기에 비하여 하드웨어의 비용이 적은 특징을 갖는다.

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디지탈 신호처리용 고정 소수점 최적화 유틸리티 (Fixed-point optimization utility for digital signal processing programs)

  • 김시현;성원용
    • 전자공학회논문지C
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    • 제34C권9호
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    • pp.33-42
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    • 1997
  • Fixed-point optimization utility software that can aid scaling and wordlength determination of digital signal processign algorithms written in C or C$\^$++/ language is developed. This utility consists of two programs: the range estimator and the fixed-point simulator. The former estimates the ranges of floating-point variables for automatic scaling purpose, and the latter translates floating-point programs into fixed-point equivalents for evaluating te fixed-point performance by simulation. By exploiting the operator overloading characteristics of C$\^$++/ language, the range estimation and the fixed-point simulation can be conducted just by modifying the variable declaration of the original program. This utility is easily applicable to nearly all types of digital signal processing programs including non-linear, time-varying, multi-rate, and multi-dimensional signal processing algorithms. In addition, this software can be used for comparing the fixed-point characteristics of different implementation architectures.

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고체산화물 연료전지/마이크로 가스터빈 하이브리드 시스템의 성능 해석 (Performance Analysis of a Solid Oxide Fuel Cell/Micro Gas Turbine Hybrid System)

  • 양진식;송태원;김재훈;손정락;노승탁
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2005년도 춘계학술대회
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    • pp.273-276
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    • 2005
  • Performance analysis of a solid oxide fuel cell/micro gas turbine hybrid system is conducted at design-point and part-load conditions and its results are discussed in this study. With detailed considerations of the heat and mass transfer phenomena along various flow streams of the SOFC, the analysis based on a quasi-2D model reasonably predicts its performance at the design-point operating conditions. In case of part-load operations, performance of the hybrid system to three different operation modes(fuel only control, speed control, and VIGV control) is compared. It is found that the simultaneous control of both supplied fuel and air to the system with a variable MGT rotational speed mode is the optimum choice for the high performance operation. And then, the dynamic characteristics of a solid oxide fuel cell are briefly introduced.

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벨마우스 깊이가 다른 소형축류홴의 공력특성에 대한 실험적 연구 (Experimental Study on the Aerodynamic Performance Characteristics of a Small-Size Axial Fan with the Different Depths of Bellmouth)

  • 김장권;오석형
    • 동력기계공학회지
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    • 제17권6호
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    • pp.73-78
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    • 2013
  • A Small-size axial fan(SSAF) has widely been utilized to circulate a cooling air in a refrigerator, etc. Generally, the aerodynamic performance of SSAF is strongly dependent upon the depth between SSAF and bellmouth, and it includes axial, partially stalled, mostly stalled and radial flow regions according to the flow coefficient. In this study, four kinds of bellmouth depths were considered to analyze the aerodynamic performance of SSAF. As a bellmouth depth increases, a maximum flowrate decreases, but a maximum static pressure increases. Also, stall region includes an inflection point in all aerodynamic performance curves. Finally, a static pressure efficiency shows the maximum value of 37%.

KDD에 기반한 경영성과 분석 시스템 구현 (Implementation of Management performance Analysis System with KDD)

  • 안동규;조성훈
    • 한국디지털정책학회:학술대회논문집
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    • 한국디지털정책학회 2004년도 춘계학술대회
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    • pp.575-592
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    • 2004
  • In modern dynamic management environment, there is growing recognition that? information & knowledge management systems are essential for CEO's efficient/effective decision making. As a key component to cope with this current, we suggest the management performance analysis syystem based on Knowledge Discovery in Database (KDD). The system measures management performance that is considered with both VA(Value- Added), which represents stakeholder's point of view and EVA(Economic Value-Added), which represents shareholder's point of view. The relation ship between management performance and some 80 financial ratios is analyzed, and then important financial ratios are drawn out. In analyzing the relationship, we applied KDD process which includes such as multidimensional cube, OLAP(On-Line Analytic Process), data mining and AHP(Analytic Hierarchy Process). To demonstrate the performance of the system, we conducted a case study using financial data over the 16-years from 1981 to 1996 of Korean automobile industry which is taken from database of KISF AS(Korea Investors Services Financial Analysis System).

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흡기가습 중형 디젤 엔진의 NOx 저감 평가를 위한 성능 해석 연구 (Engine Performance Simulation to Evaluate the NOx Reduction of Charge Air Moisturizer System in a Medium Speed Diesel Engine)

  • 김기두;박형근;김병석;하지수
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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    • pp.15-16
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    • 2005
  • In this study, the characteristics of NOx reduction by using charge air moisturizer system were evaluated by engine performance simulation in medium speed diesel engines. The results of performance simulation were verified by experimental results of single cylinder medium speed diesel engine equipped with charge air moisturizer system. Performance simulation was carried out to evaluate charge air moisturizer system of turbocharged diesel engine, HYUNDAI HiMSEN 9H25/33 engine. Those results show 50% NOx reduction at dew point $80^{\circ}C$ and charge air pressure 4bar.

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부가가치와 경제적부가가치를 결합한 경영성과평가에 관한 실증적 연구 (Study on the Business Performance Evaluation with VA and EVA)

  • 김태성;구일섭;임익성
    • 품질경영학회지
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    • 제29권4호
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    • pp.153-160
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    • 2001
  • The proposed system measures business performance by considering both VA(Value-Added), which represents stakeholder's point of view and EVA(Economic Value-Added), which represents shareholder's point of view. To do so, we suggest a business performance scheme which utilizes VA per Capita (Value- Added/Workers) and EVA to Invested Capital(Economic Value-Added /Invested Capital). For effective measurement of business performance, we consider simultaneously not only quantitative financial factors such as VA, EVA and cash flow but also qualitative value drivers such as defect ratio, inventory level, customer satisfaction, enterprise culture and so on. However, we don't consider the qualitative factors due to the limited data. To demonstrate the performance of the system, we conducted a case study using financial data of Korean automobile industry over 16 years from 1981 to 1996, which is taken from database of KISFAS (Korea Investors Services Financial Analysis System).

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Genetic Algorithm에 기반한 경영성과분석 시스템 구현 (Implementation of Management performance Analysis System with Genetic Algorithms)

  • 안동규;조성훈
    • 한국디지털정책학회:학술대회논문집
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    • 한국디지털정책학회 2003년도 창립학술대회
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    • pp.191-210
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    • 2003
  • In modern dynamic management environment, there is growing recognition that information & knowledge management systems are essential for CEO's Efficient/effective decision making, As a key component to cope with this current, we suggest the management performance analysis system based on Knowledge Discovery in Database (KDD). The system measures management performance that is considered with both VA(Value-Added), which represents stakeholder's point of view and EVA(Economic Value-Added), which represents shareholder's point of view, The relationship between management performance and some 80 financial ratios is analyzed, and then important financial ratios are drawn out. In analyzing the relationship, we applied KDD process which includes such as multidimensional cube, OLAP(On -Line Analytic Process), data mining and AHP(Analytic Hierarchy Process). To demonstrate the performance of the system, we conducted a case study using financial data over the 16-years from 1981 to 1996 of Korean automobile industry which is taken from database of KISFAS(Korea Investors Services Financial Analysis System).

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