• 경영과정보연구
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• 제5권
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• pp.81-101
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• 2000

The purpose of this comparative study is to compare and evaluate venture business of electronic and communication industry by Data Envelopment Analysis(DEA). DEA is a linear programming-based technique that converts multiple input and output measures into a single comprehensive measures of productive efficiency. In this paper, the CCR model and trend analysis model are used to examine the efficiency of 18 venture business. Input variables are number of employees. raw-material costs and production capability and output variables are real production, sales revenues and net income after taxes. DEA approach broad information like as efficiency level of each Decision Making Unit(DMU), reference group of efficiency improvement and trends of efficiency shift. Finally, the correlation of input and output variables are examined to examine the relationship among variables.

• 수산경영론집
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• 제47권2호
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• pp.1-14
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• 2016

This study applied the Stochastic Frontier Analysis to estimate which independent variable affects to efficiency of aquaculture household. This study used wage and facility scale as input variables, sales volume as an output variable to estimate efficiency. Also, the study used region, species, water quality to estimate technical inefficiency factors of the model. The data used for this study were obtained by the operating costs survey using 1:1 interview method. The study selected translog production model with technical inefficiency term estimated as half-normal distribution. In addition, the study used pearson and spearman correlation coefficient among efficiency estimating models. Also, the study analysed differences among estimated efficiencies through t-test, and showed us 0.1793 in species, 0.4677 between Geojae and Masan.

• Journal of Power Electronics
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• 제2권1호
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• pp.67-75
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• 2002

This paper presents the control algorithm for maximum efficiency drives of an induction motor system with the high dynamic performance. This system uses a simple model of the induction motor that includes equations of the iron losses. The model, which only requires the parameters of the induction motor, is referred to a field-oriented frame. The minimum point of the input power can be obtained at the steady state condition. The proposed optimal efficiency control algorithm calculates the reference torque and flux currents for the vector control of the induction motors. A 32 bit floating point TMS320C32 DSP chip implements the drive system with the efficiency optimization controller. The results show the effectiveness of the control strategy Proposed for the induction motor drive.

• 한국구조물진단유지관리공학회 논문집
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• 제5권3호
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• pp.203-211
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• 2001

This paper presents load transfer efficiency of skewed transverse joint of jointed concrete pavement with the fatigue model test. A 1/12 scale model was used to satisfy the geometry, loading, material similitude, which are variables to the skew angel of transverse joint. As the test results by fatigue load 700kgf applied, the deflection and stress of transverse joint were decreased as to increasing of skew angle of transverse joint. In addition, load transfer efficiency of transverse joint with skew angle is better than the load transfer efficiency of transverse joint without skew angle.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2008년도 추계학술대회
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• pp.189-199
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• 2008

It is good to use DEA method as it can measure the efficiency without depending on a specific function like cost function. The method also finds out the most efficient group among the sample groups and gives us a specific number. For example, it shows what kind of factor of inefficient group gives how much input and produces how much output. Originally DEA, which was developed by Charnes, Cooper and Rhodes, allows us not only to measure the relative efficiency of Decision Making Units(DMUs) of non-profit organizations whose success cannot be measured by a single bottom-line figure such as profit but also to integrate several variables, which have different measuring scale, into a single model. Therefore we can use physical scales and financial scales simultaneously in the same model without any transformation process. In this study, price and measurable performance indexes of vehicles are used as input and outputs respectively. The purpose of this study is to propose an effective approach for evaluating the relative efficiency of vehicles and to determine the vehicles have high performance efficiency compared to product cost.

• 한국소음진동공학회논문집
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• 제18권3호
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• pp.361-367
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• 2008

Many trials have been used to model room impulse responses, all attempting to provide efficient representations of room acoustics. The traditional model designs for room impulse response seem to fail in accuracy, controllability, or computational efficiency. In the time domain, room impulse responses are generally considered as combination of the three Parts having different acoustic characteristics, initial time delay, early reflection, and late reverberation. This paper introduces new learning hybrid model for room impulse responses. In this proposed model, those three parts are modeled using different models with learning algorithms that determine the boundary of each model in the hybrid model. By the simulation with measured room impulse responses, the performance of proposed model shows the best efficiency in views of computational burden and modeling error.

• 한국CDE학회논문집
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• 제10권1호
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• pp.49-60
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• 2005

Existing CAD systems have configured geometry data and it is necessary to extend the configured geometry into a knowledge-based system. An intelligent CAD system emerged to provide such a knowledge-based system. However the intelligent CAD system has a limited product model to represent various knowledge models. This paper presents a model, called extended intelligent CAD model, which can extend the product model of the intelligent CAD system into further detailed knowledge model. The extended intelligent CAD model includes a whole design process knowledge and an efficiency of the model has been verified via a knowledge based wiper design system. The model can improve the functionality and efficiency of the existing CAD systems.

• Journal of Information Processing Systems
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• 제15권6호
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• pp.1335-1349
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• 2019

Crowdsensing technologies can improve the efficiency of smart parking system in comparison with present sensor based smart parking system because of low install price and no restriction caused by sensor installation. A lot of sensing data is necessary to predict parking lot saturation in real-time. However in real world, it is hard to reach the required number of sensing data. In this paper, we model a saturation predication combining a time-based prediction model and a sensing data-based prediction model. The time-based model predicts saturation in aspects of parking lot location and time. The sensing data-based model predicts the degree of saturation of the parking lot with high accuracy based on the degree of saturation predicted from the first model, the saturation information in the sensing data, and the number of parking spaces in the sensing data. We perform prediction model learning with real sensing data gathered from a specific parking lot. We also evaluate the performance of the predictive model and show its efficiency and feasibility.

• 한국콘텐츠학회논문지
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• 제17권2호
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• pp.316-326
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• 2017

본 연구에서는 대표적인 지역단위 직업능력개발 공공서비스인 지역맞춤형일자리창출지원사업의 효율성을 분석하기 위해서, 충청남도에서 2014년에 수행된 27개 사업을 대상으로 DEA를 사용하여 효율성을 분석하고, 2013년에 수행된 18개 사업의 효율성과 비교분석했으며, 비효율성에 대한 개선방안을 제시하기 위해서 대표적인 3개의 DMU에 대해서 비효율정도를 살펴봤다. DEA 모형은 CCR모형, BCC모형 및 SE(CCR/BCC)에 의한 규모효율성에 대해서 살펴봤다. 분석결과 2014년은 2013년보다 총사업비와 사업개수가 증가하였지만, 비효율적인 사업이 증가하여 전체 효율성은 감소한 것으로 나타났다. 따라서 효율성 개선을 위해서는 사업비에서 많은 부분을 차지하는 인건비와 직접경비를 사업별로 적절히 배분함으로써 전체 사업의 효율성을 제고할 것을 제시하였으며, 특히 사업비가 큰 대형사업의 경우에는 사업규모를 줄이는 것이 전체 효율성을 제고하는데 가장 중요한 요인이라는 점을 확인하였다. 본 연구를 통해서 직업능력개발 공공서비스의 효율성을 분석하고 효율성 제고방안을 도출하는 연구모형을 제시했으며, 이에 기반하여 성과관리 연구의 영역을 다양한 공공서비스의 효율성을 분석하는 분야로 확대할 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.97-103
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• 2001

The effects of the electrohydrodynamic (EHD) flow and turbulent diffusion on the collection efficiency of a model ESP composed of the plates with a cavity were studied through numerical computation. The electric field and ion space charge density were calculated by the Poisson equation of the electrical potential and the current continuity equation. The EHD flow field was solved by the continuity and momentum equations of the gas phase including the electrical body force induced by the movement of ions under the electric field. The RNG $k-{\varepsilon}$ model was used to analyze the turbulent flow. The particle concentration distribution was calculated from the convective diffusion equation of the particle phase. As the ion space charge increased, the particulate collection efficiency increased because the electrical potential increased over the entire domain in the ESP. The collection efficiency decreased and then increased, i.e. had a minimum value, as the EHD circulating flow became stronger when the electrical migration velocity of the charged particle was low. However, the collection efficiency decreased with the stronger EHD flow when the electrical migration of the particle was higher relatively. The collection efficiency of the model ESP increased as the turbulent diffusivity of the particle increased when the electrical migration velocity of the particle was low. However, the collection efficiency decreased for increasing the turbulent diffusivity when the electrical migration of the particle was higher relatively.