• 대한조선학회논문집
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• 제61권3호
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• pp.200-207
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• 2024

A multi-component force sensor has been developed to measure force and moment components in high-speed flow media for submerged models. The size of the test model is determined based on the Reynolds number of the model at the test speed and expected blockage effect. A two-component force sensor unit has been created by assembling pairs of column elements arranged symmetrically under an eccentric load. The six-component force sensor is constructed with symmetric arrangements of two-component force sensor units in a rectangular plane. The signals generated from the strain gauges attached to the surface of the elements can be converted into force signals. The performance of the waterproof six-component force sensor has been evaluated through calibration. A simplified interference decomposition procedure has been introduced to increase the accuracy of measurement.

• 한국건설순환자원학회논문집
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• 제3권3호
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• pp.268-276
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• 2015

본 논문에서는 탄소저감을 위한 산업부산물 사용 증대 및 시공성능 향상을 위하여 시멘트 사용량을 80% 이상 감소시킨 탄소저감형 4성분계 고유동 콘크리트를 제조하여 품질특성, 및 탄소저감 성능을 수행하였다. 탄소저감형 4성분계 고유동 콘크리트의 품질특성 평가를 수행한 결과 다량의 산업부산물을 혼합하여 시멘트 사용량을 80% 이상 감소시킨 배합에서 목표 성능을 만족하는 품질을 얻을 수 있었으며, 유동특성, 역학특성 및 내구특성의 경우 기존 기준 배합과 비교하여 다소 성능이 감소되는 경향이 나타났지만 소요 성능 수준 이상의 성능을 만족할 수 있는 것으로 판단된다. 또한, 탄소저감형 다성분계 고유동 콘크리트의 탄소저감 성능을 분석하기 위하여 콘크리트의 전 과정 평가를(LCA) 실시한 결과 기존 기준 배합과 비교하여 약 62.2%의 탄소저감 성능이 있는 것으로 나타났으며, 제조비용의 경우 약 24.5%의 원가 절감이 되는 것으로 나타났다.

• 한국통신학회논문지
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• 제33권2C호
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• pp.192-199
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• 2008

Ultra-wideband (UWB) 시스템의 동기화에 대한 이제까지의 연구에서는 참조 신호와 다중경로 성분들 중 어느 한 성분과의 위상을 맞추는 것을 동기화라 정의하고 빠르게 동기화하는 기법에 대하여 연구하였다. 그러나 다중경로 성분들은 서로 다른 전력을 갖기 때문에, 동기화 이후 과정들에서, 낮은 전력을 갖는 다중경로 성분에서 동기화가 될 경우에는 좋지 않은 성능을 가지며, 높은 전력을 갖는 다중경로 성분에서 동기화 할 경우에는 좋은 성능을 갖는다. 일반적으로 첫 번째 다중경로 성분이 가장 큰 전력을 가지며, 따라서 첫 번째 다중경로 성분에서 동기화함으로서 동기화 이후 과정들의 성능을 향상시킬 수 있다. 본 논문에서는 첫 번째 다중경로 성분과 참조 신호의 위상이 맞았을 때를 동기화라 새롭게 정의하고, 최대 우도 (maximum-likelihood: ML) 방법을 이용하여 UWB 다중경로 채널에서 첫 번째 다중경로 성분을 찾기 위한 최적 결정 법칙을 유도하였으며, 동시에 이에 바탕을 둔 준 최적 결정 법칙을 제안하였다. 모의실험을 통해, 새로운 동기화의 정의에 따라 동기화하였을 때, 그렇지 않을 때보다 좋은 복조 성능을 갖는 것을 확인할 수 있었으며, 본 논문에서 제안된 최적 및 준 최적 결정 법칙은 기존 결정 법칙과 비교할 때 월등한 성능을 갖는 것을 확인할 수 있었다.

• 한국유체기계학회 논문집
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• 제6권4호
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• pp.38-44
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• 2003

Flow field downstream of an inducer was measured to see the flow and performance characteristics of a turbopump inducer. A large axisymmetric collector instead of a volute casing was installed to obtain circumferentially uniform flow - without interaction of the inducer and the volute. A conventional 3-hole probe was used to measure the flow. At inducer exit, axial component of absolute velocity decreased on hub region with decrease in flow rate. Tangential velocity component, static pressure, and total pressure increased from hub to tip. Relative flow angle from tangential direction was a little higher than outlet blade angle at flow coefficient ${\phi}=0.087$ and 0.073. Dynamic pressure was $53\%$ of the mean total pressure at inducer exit at ${\phi}=0.073$.

• 전력전자학회논문지
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• 제18권6호
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• pp.565-572
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• 2013

The sensorless speed control using the improved full-order flux observer for PMSM is proposed in this paper. A conventional full-order flux observer has a drawback that the estimated flux of this observer contains the ripple component at the low speed range due to the increased gains of the convectional full-order flux observer. The improved full-order flux observer with the modified gains guarantee the improved estimation performance without ripple component at the from zero to high speed range. To identify the performance of proposed observer, the simulation and experiment are conducted and this performance is compared with the conventional full-order observer.

• 한국자동차공학회논문집
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• 제2권2호
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• pp.12-23
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• 1994

In order to investigate the effect of turbulent intensity on combustion characteristics, new flame factor model was developed. The principal study is the evaluation of interaction of swirl, tumble and unstrutural component of flow characteristics and correlation between turbulent intensity and flame factor. Computational and experimental study has been, performed such as quasi-dimensional cycle simulation, three dimensional flow analysis, engine performance test and diagnostic simulation. From these studies, it was found that flame factor was a function of engine speed and turbulent intensity.

• 설비공학논문집
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• 제10권2호
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• pp.227-237
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• 1998

A numerical simulation has been carried out for the automotive air conditioning system. The purpose of this simulation is to present the methods for simulating car air conditioning components, systems and cool-down performance by computerized mathematical model and to analyze the performance of A/C system. In analyzing the heat exchanger(evaporator and condenser), the finite volume model which has a merit in predicting the temperature field in detail because it can consider partial variation of thermal property and heat transfer coefficient is used. In analyzing the compressor, the polytropic approach which regards the actual compression process as a reversible polytropic process is employed. In analyzing vehicle passenger compartment, the thermal network is employed to simulate the car cool down process. This A/C system program can be used for analyzing a component performance when a component is alternated or designed and for analyzing the engine cooling system when A/C system is operated.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.414-416
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• 2009

In order to build a transient simulation program for a high thrust liquid rocket engine(LRE), a static performance simulation program for components were made. The components were the thrust chamber (combustion chamber and supersonic nozzle), centrifugal pump (impeller and volute casing), impulse turbine, and flow control devices (control valve and orifice). Simplified mathematical models based on classical thermodynamic and inviscid theories were used to remove complexity and enhance the utility of the program. We examined the results of each program qualitatively for validate each component modeling.

• Journal of Information Technology Applications and Management
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• 제11권1호
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• pp.15-37
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• 2004

This study attempts to investigate the industrial practices of the web site development methodologies and their impacts on the web site development project performance. Most of Korean web site development firms currently use customized component-based development(CBD) methodologies that have been internally developed. The methodologies generally being accepted by web site developers, however, did not emerge yet. In addition, this study shows that indiscreet applications of various methodologies and techniques might cause negative impacts on the project performance since the web site development projects are also exposed to most of the risk factors identified in the traditional systems development.

• 대한음성학회지:말소리
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• 제53호
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• pp.93-102
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• 2005

The performance of a speech recognition system is generally degraded in telephone environment because of distortions caused by background noise and various channel characteristics. In this paper, data-driven temporal filters are investigated to improve the performance of a specific recognition task such as telephone speech. Three different temporal filtering methods are presented with recognition results for Korean connected-digit telephone speech. Filter coefficients are derived from the cepstral domain feature vectors using the principal component analysis. According to experimental results, the proposed temporal filtering method has shown slightly better performance than the previous ones.