• 제목/요약/키워드: Alternative mode

검색결과 376건 처리시간 0.027초

3.4L 급 농기계용 디젤-천연가스 혼소 엔진 개발 (A Development of an 3.4L-class Diesel-LNG Dual Fuel Engine for Farming Machine)

  • 심주현;고춘식;이상민;이옥재;이창언
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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    • pp.187-190
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    • 2012
  • An experimental study was performed to provide the effect of PM reduction and the improvement of diesel alternative ratio utilizing diesel-natural gas dual-fuel combustion mode in a retrofit 3.4-liter diesel engine. In order to achieve the same power as the original diesel engine, engine control unit (ECU) of the dual-fuel engine was calibrated. As a result, diesel alternative ratio was found that the maximum value of diesel alternative ratio was about 96%. Finally PM emission experiment was performed in C1-8 mode cycle and it was shown PM emission was extremely reduced down to $7.42{\ast}10^{-7}g/kWh$ comparing with mechanical diesel engine.

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전류모드제어를 위한 연속시간모델의 새로운 유도 방법 (Alternative Derivation of Continuous-Time Model for Current-Mode Control)

  • 정동열;홍성수;최병조;안현식;사공석진
    • 전력전자학회논문지
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    • 제8권2호
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    • pp.137-142
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    • 2003
  • 전류모드제어의 널리 알려진 두가지 연속시간모델이 소신호 예측에서 현저한 차이점을 보인다 따라서, 소신호에서의 불일치의 원인을 명백하게 하려고 한다. 본 논문에서는 전류모드제어를 위한 연속시간모델을 유도하는 다른 방안을 제시한다. 본 논문에서 제안한 전류모드제어모델과 기존의 전류모드제어모델과 모델링 방법의 차이점을 제시하고, 제안된 연속시간모델에 대한 타당성을 검증하기 위해 하드웨어실험과 PWM 블록의 모델에 샘플링효과를 포함하는 알고리즘을 제안하고, 전류루프이득을 시뮬레이션과 하드웨어 실험 결과와 비교, 검토하였다.

전류모드제어를 위한 연속시간모델의 새로운 유도 방법 (Alternative Derivation of Continuous-Time Model for Current-Mode Control)

  • 정동열;홍성수;최병조;사공석진
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2002년도 추계학술대회 논문집
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    • pp.218-222
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    • 2002
  • Two existing continuous-time models for the current-mode control have presented noticeable differences in their small-signal predictions. As an attempt to clarify the origin of these disparities, this paper presents an alternative way of deriving a continuous-time model for the current-model control. The results of this paper would provide insights to comprehend the dissimilarity in the modeling method and final results of the earlier models of current-mode control.

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Mode identifiability of a cable-stayed bridge under different excitation conditions assessed with an improved algorithm based on stochastic subspace identification

  • Wu, Wen-Hwa;Wang, Sheng-Wei;Chen, Chien-Chou;Lai, Gwolong
    • Smart Structures and Systems
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    • 제17권3호
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    • pp.363-389
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    • 2016
  • Deficient modes that cannot be always identified from different sets of measurement data may exist in the application of operational modal analysis such as the stochastic subspace identification techniques in large-scale civil structures. Based on a recent work using the long-term ambient vibration measurements from an instrumented cable-stayed bridge under different wind excitation conditions, a benchmark problem is launched by taking the same bridge as a test bed to further intensify the exploration of mode identifiability. For systematically assessing this benchmark problem, a recently developed SSI algorithm based on an alternative stabilization diagram and a hierarchical sifting process is extended and applied in this research to investigate several sets of known and blind monitoring data. The evaluation of delicately selected cases clearly distinguishes the effect of traffic excitation on the identifiability of the targeted deficient mode from the effect of wind excitation. An additional upper limit for the vertical acceleration amplitude at deck, mainly induced by the passing traffic, is subsequently suggested to supplement the previously determined lower limit for the wind speed. Careful inspection on the shape vector of the deficient mode under different excitation conditions leads to the postulation that this mode is actually induced by the motion of the central tower. The analysis incorporating the tower measurements solidly verifies this postulation by yielding the prevailing components at the tower locations in the extended mode shape vector. Moreover, it is also confirmed that this mode can be stably identified under all the circumstances with the addition of tower measurements. An important lesson learned from this discovery is that the problem of mode identifiability usually comes from the lack of proper measurements at the right locations.

CNG 승용 자동차의 배출가스 특성에 관한 실험적 연구 (Experimental Study of Emission Characteristics for CNG Passenger Car)

  • 김현준;이호길
    • 한국가스학회지
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    • 제19권6호
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    • pp.34-39
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    • 2015
  • 최근 차량용 에너지의 소비는 대부분 화석연료로부터 사용된다. 기존 화석 연료를 사용하는 자동차보다 친환경적이며 저렴하고 재생이 가능한 연료의 요구증대로 대체연료 자동차산업이 강조되고 있다. 오늘날 고옥탄가와 높은 자기발화온도 특징을 가지고 있는 천연가스는 저렴한 비용, 기존 화석연료보다 풍부한 매장으로 기존 스파크 점화엔진인 가솔린엔진의 대체에너지로 간주되고 있다. 본 연구는 기존 2리터 가솔린 엔진에 CNG 가스 분사시스템을 장착하여 전소 및 혼소 연료분사시스템을 설치하였다. 또한 CNG전소 및 가솔린/CNG 혼소차량의 ECU 제어전략을 최적화 하였다. 혼소차량에 대하여 NEDC모드 주행결과 가솔린 차량 대비 혼소차량의 CO2 저감율을 16%확인하였다. 또한 CO와 HC의 배기가스 배출량은 가솔린 차량과 동등한 수준을 확보하였다. 하지만 NOx의 배기가스 배출수준은 증가된 현상을 확인할 수 있었다.

Adaptive Coefficient Scanning Based on the Intra Prediction Mode

  • Choi, Byeong-Doo;Kim, Jin-Hyung;Ko, Sung-Jea
    • ETRI Journal
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    • 제29권5호
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    • pp.694-696
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    • 2007
  • This letter presents an adaptive coefficient scanning method for intra mode coding in H.264. The proposed adaptive scanning uses six alternative scanning orders based on the intra prediction mode. Experimental results show that the proposed method improves the coding efficiency up to 3% compared to conventional scanning methods without additional computations.

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Conjoint Choice Model을 이용한 주제공원 이용자들의 선택행동 연구 (A Study on the Theme Park Users's Choice behavior: Application of Conjoint Choice Model)

  • 홍성권
    • 한국조경학회지
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    • 제28권1호
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    • pp.19-28
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    • 2000
  • The purposes of this study are two folds: a) to introduce conjoint choice model to research the choice behavior of theme park users, and b) to suggest the strategies to strengthen the competitiveness of theme parks. The major four theme parks in Seoul metropolitan areas were selected as study areas. A leading polling agency was employed to select 432 respondents by probability sampling and to conduct face-to-face interview. Both alternative generating and choice set generating fractional factorial design were conducted simultaneously to meet the necessary and sufficient conditions for calibration of the conjoint choice model. Dummy coding was used to represent the attribute levels, and the alternative-specific model was calibrated. The goodness-of-fit of the model was quite satisfactory($\rho$$^2$=0.47950), and most parameters values had to expected sign and magnitude. Car was preferred transport mode to shuttle bus for visiting theme parks ; however the most ideal attribute levels only were estimated significantly. Most attribute levels of shuttle bus were estimated significantly except the Dream Land, which is the least attractive park among study areas. Simulation results showed that the shuttle bus was a mode worth providing to switch the current car dominant visiting pattern of theme parks, which will be one the effective strategies to attract more patrons, especially for potential users adjacent to parks. Several ideals were suggested for future researches, in terms of utilization of more general utility function and new base alternative, and inclusion of more salient attributes such as constraints in the model.

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수익성을 감안한 경전철의 최적노선 결정방법에 관한 연구 (A Study on the Determination of Optimum L.R.T Route from the Viewpoint of Revenue Maimization Principles)

  • 원제무;박창호;이성모
    • 대한교통학회지
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    • 제12권3호
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    • pp.29-47
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    • 1994
  • Although subway system continues to be the backbone of transportation systems in a city like Seoul, there will still be areas across the city where subway services are not avaliable. Interest has steadily grown to fill this missing routes in overall urban transportation system. Light Rail Transit (L.R.T) system has been recently thought to be an appropriate mode of transportation by businessmen, professionals and transportation industry. In this regards, the purpose of this study is to explore whether L.R.T can be a feasible form of urban rail mode in the context of Seoul. First, the study develops the mathematical models to derive optimum route networks and stations. Integer Programming is employed to determine whether alternative routes are financially viable from the viewpoint of revenue maximization principles. Second, mathematical models developed are applied to Yoido area in order to examine the validity of model structures. The models constructed turns out be capable of handling alternative routes and stations. Application of models are successfully carried out to derive financially feasible set of routes and stations.

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변형률 센서를 이용한 구조물의 동적 모니터링 (Dynamic monitoring of structures using strain sensors)

  • 최성훈;은종필;강동훈
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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    • pp.387-392
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    • 2009
  • Measurement of dynamic characteristics are widely used to detect defects in mechanical or civil structures. The most common approach is to measure changes in frequency spectrum or mode shapes using accelerometers. An alternative to using mode shapes is using stain modes. Strain is more sensitive to local defects than displacement, and hence stain modes measurement is an efficient in structural health monitoring. This paper deals with dynamic monitoring of a beam structure using strain sensors. Resistive strain gages and FBG strain gages are used and their characteristics are compared. It has been known that resistive strain gages are week to EMI environment and suffers from noise at high frequency range. It has been shown that the FBG sensor is a good alternative that overcomes such difficulties.

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A New Method of Collision Mode Evolution for Three-Dimensional Rigid Body Impact With Friction

  • Park, Jong-Hoon;Chung, Wan-Kyun;Youm, Young-Il
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2004년도 ICCAS
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    • pp.1769-1775
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    • 2004
  • In presence of collision between two rigid bodies, they exhibit impulsive behavior to generate physically feasible state. When the frictional impulse is involved, collision resolution can not be easily made based on a simple Newton's law or Poisson's law, mainly due to possible change of collision mode during collision, For example, sliding may change to sticking, and then sliding resumes. We first examine two conventional methods: the method of mode evolution by differential equation, and the other by linear complementarity programming. Then, we propose a new method for mode evolution by solving only algebraic equations defining mode changes. Further, our method attains the original nonlinear impulse cone constraint. The numerical simulation will elucidate the advantage of the proposed method as an alternative to conventional ones.

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