• 한국자동차공학회논문집
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• 제22권2호
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• pp.190-196
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• 2014

Exhaust system by reinforcement of environment regulation came to the foe study necessity. And Exhaust system has necessary to increase the engine performance and silence. From this cause, Automobile has significantly considered production expense. this study makes process for checking the characteristics about Exhaust variable valve within muffler. Variable valve might reduce the baffle within muffler, It was possible to remove the front muffler. Therefor, To miniaturize a size of muffler might be increased by performance through cost-cutting effect and controling of back pressure. Because the Study on Variable valve installed within muffler, to measure the real data was hardly resulted one of the assignments. From manufactured conduct device, might measure data one of piece which was up-graded of problem. Considering to these point, stressed pressure distribution has analyzed on cross section, floating characteristics about velocity distribution around variable valve using analysis as computational fluid dynamics of Ansys with completed measurement data.

• 에너지공학
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• 제6권1호
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• pp.11-18
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• 1997

본 논문은 에너지 효율이 높은 열병합발전시스템을 대상으로 유전알고리즘을 적용하여 단기운전계획을 수립하였다. 특히 열병합발전시스템의 효율은 약 70%이지만 효율이 일정하지 않을 뿐만 아니라 비선형적인 특징을 가지므로 실제 산업체의 열병합발전소의 데이터를 기초로 하여 적합한 가변효율방정식을 구하였다. 또한 본 논문에서 적용된 유전알고리즘은 계산시간의 감소와 높은 정밀도를 가진 실변수 유전알고리즘으로 시뮬레이션 하였다. 그 결과로 가변효율을 가진 열병합발전시스템의 단기운전계획이 유전알고리즘을 적용하여 적절하게 운전계획이 수립되고 있음을 나타내었으며 각종 보조설비가 유연성 있게 협력하며 필요시마다 효율적으로 운전되고 있음을 확인하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.557-562
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• 2004

A surface-piercing barrier model is presented for understanding morphological development in the sheltered region and investigating the main factors causing the severe accumulation. Surface-piercing structures like vertical barriers, surface docks and floating breakwaters are recently favored from the point of view of a marine scenario since they do not in general partition the natural sea. The numerical solutions are compared with experimental data on wave profiles and morphological change rates within a rectangular harbor of a constant depth protected by surface-piercing thin breakwaters as a simplified problem. Our numerical study involves several modules: 1) wave dynamics analyzed by a plane-wave approximation, 2) suspended sediment transport combined with sediment erosion-deposition model, and 3) concurrent morphological changes. Scattering waves are solved by using a plane wave method without inclusion of evanescent modes. Evanescent modes are only considered in predicting the reflection ratio against the vertical barrier and energy losses due to vortex shedding from the lower edge of plate are taken into account. A new relationship to relate the near-bed concentration to the depth-mean concentration is presented by analyzing the vertical structure of concentration. The numerical solutions were also compared with experimental data on morphological changes within a rectangular harbor of constant water depth. Through the numerical experiments, the vortex-induced flow appears to be not ignorable in predicting the morphological changes although the immersion depth of a plate is not deep.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권9호
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• pp.4429-4447
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• 2018

Local binary descriptors are well-suited for many real-time and/or large-scale computer vision applications, while their low computational complexity is usually accompanied by the limitation of performance. In this paper, we propose a new optimization framework, RLDB (Robust-LDB), to improve a typical region-based binary descriptor LDB (local difference binary) and maintain its computational simplicity. RLDB extends the multi-feature strategy of LDB and applies a more complete region-comparing configuration. A cascade bit selection method is utilized to select the more representative patterns from massive comparison pairs and an online learning strategy further optimizes descriptor for each specific patch separately. They both incorporate LDP (linear discriminant projections) principle to jointly guarantee the robustness and distinctiveness of the features from various scales. Experimental results demonstrate that this integrated learning framework significantly enhances LDB. The improved descriptor achieves a performance comparable to floating-point descriptors on many benchmarks and retains a high computing speed similar to most binary descriptors, which better satisfies the demands of applications.

• 디지털콘텐츠학회 논문지
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• 제17권3호
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• pp.165-172
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• 2016

GPU 기반 병렬처리에서 대규모 데이터의 인접 정보 검색(nearest neighbor search)에서 Morton code의 역할이 점점 더 중요하게 부각되고 있으며 그 응용 사례도 점차 증가하고 있다. 본 논문에서는 Tero Karras가 제안한 float 형 변수에 기반한 $[0,1]^3$ 공간 내의 3차원 기하 정보를 32비트 unsigned int형 Morton code로 변경하는 기존의 방법을 논의하고 그 기하학적인 의미를 분석함으로써, 보다 높은 해상도를 구현할 수 있는 64비트 unsigned long long형의 Morton code 변환 알고리듬을 제안한다. 제안하는 알고리듬은 GPU에서 구현되었을 때 CPU에서 실행하는 것보다 약 1000배 수준의 성능 향상을 달성한다.

• Nuclear Engineering and Technology
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• 제43권3호
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• pp.243-256
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• 2011

This paper considers the concept of analog computing based on a cellular neural network (CNN) paradigm to simulate nuclear reactor dynamics using a time-dependent second order form of the neutron transport equation. Instead of solving nuclear reactor dynamic equations numerically, which is time-consuming and suffers from such weaknesses as vulnerability to transient phenomena, accumulation of round-off errors and floating-point overflows, use is made of a new method based on a cellular neural network. The state-of-the-art shows the CNN as being an alternative solution to the conventional numerical computation method. Indeed CNN is an analog computing paradigm that performs ultra-fast calculations and provides accurate results. In this study use is made of the CNN model to simulate the space-time response of scalar flux distribution in steady state and transient conditions. The CNN model also is used to simulate step perturbation in the core. The accuracy and capability of the CNN model are examined in 2D Cartesian geometry for two fixed source problems, a mini-BWR assembly, and a TWIGL Seed/Blanket problem. We also use the CNN model concurrently for a typical small PWR assembly to simulate the effect of temperature feedback, poisons, and control rods on the scalar flux distribution.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권4호
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• pp.436-442
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• 2016

An electroencephalogram (EEG)-connectome processor to monitor and diagnose mental health is proposed. From 19-channel EEG signals, the proposed processor determines whether the mental state is healthy or unhealthy by extracting significant features from EEG signals and classifying them. Connectome approach is adopted for the best diagnosis accuracy, and synchronization likelihood (SL) is chosen as the connectome feature. Before computing SL, reconstruction optimizer (ReOpt) block compensates some parameters, resulting in improved accuracy. During SL calculation, a sparse matrix inscription (SMI) scheme is proposed to reduce the memory size to 1/24. From the calculated SL information, a small world feature extractor (SWFE) reduces the memory size to 1/29. Finally, using SLs or small word features, radial basis function (RBF) kernel-based support vector machine (SVM) diagnoses user's mental health condition. For RBF kernels, look-up-tables (LUTs) are used to replace the floating-point operations, decreasing the required operation by 54%. Consequently, The EEG-connectome processor improves the diagnosis accuracy from 89% to 95% in Alzheimer's disease case. The proposed processor occupies $3.8mm^2$ and consumes 1.71 mW with $0.18{\mu}m$ CMOS technology.

• 한국해양공학회지
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• 제25권5호
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• pp.21-26
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• 2011

Seawater lift pump systems are responsible for maintaining open canal levels to provide the suction flow of circulating water pumps at the set point. The objective of this paper is to design a 2-stage mixed flow pump (for seawater lifting), investigate the new impeller modeling method, and performance improvements of the impeller by using a commercial CFD code. The rotating speed of the impeller is 1,750 rpm with a flow rate of 2,700 m3/h. A finite volume method with a structured mesh and realized k-${\varepsilon}$ turbulent model is used to guarantee a more accurate prediction of turbulent flow in the pump impeller. The performance variables such as the static head, brake horsepower, and efficiency of the mixed flow pump are compared based on changes in the impeller blade shape.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1136-1139
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• 2000

The paper describes a new and rigorous mathematical model for the rotor field oriented system with induction motor which uses the estimated speed and rotor flux based on a Model Reference Adaptive System, as well as the real-time approach. The estimated speed and rotor flux is used for the speed and flux feedback control. The stability and the convergence of the estimator are improved on the basis of hyperstability theory for non-linear systems. The real-time controller and estimator are implemented with a sampling period of $926{\mu}s$ using a dual TMS320C44 floating-point digital signal processor. The validity of the proposed method is verified by simulation, and also, the sensorless control was tested on the propulsion system simulator, used for the development of Korean High-Speed Railway Train (KHSRT) [5].

• 한국전산구조공학회논문집
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• 제19권1호
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• pp.105-111
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• 2006

돌핀계류시스템은 부유식 해양구조물의 계류장치로서 강도 및 유용도 관점에서 바람직한 대안이 될 수 있다. 돌핀계류시스템 설계과정에서 정확한 파력산정과 필요한 지지파일의 개수선정은 주요 설계요인이 된다 본 논문에서는 파의 충격하중을 포함한 외력에 대한 구조해석을 통하여 적정한 돌핀시스템의 설계과정과 형식을 제시하였다. 부유식 해양구조물을 위한 돌핀계류시스템의 경우 다수의 지지파일시스템보다 단주의 지지파일시스템이 설계관점에서, 제한적이기는 하나, 유용성이 높다는 점을 알 수 있었다.