• Journal of Power System Engineering
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• 제3권1호
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• pp.38-44
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• 1999

Subway is one of the most important transportation and its facilities are increased by the drift of population to cities in these days. But heat generation results from lighting, human and traffic increase in subway, half-closed space, gives uncomfortable sense to the subway passengers. Therefore, natural ventilation by piston effect is done to relieve uncomfortable sense. But train wind by piston effect gives uncomfortable sense to the subway passengers, too. So the numerical calculation of inflow and outflow amounts is important to predict thermal environment and reduce train wind. In case of actual survey of train wind in target station, the amount of train wind are about $3100m^3/train$ at the minimum, about $6000m^3/train$ at the maximum, about $4200m^3/train$ on average. When comparison between simulation for train wind prediction and actual survey for accuracy was done train wind prediction program showed similar results.

• Coupled systems mechanics
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• 제12권6호
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• pp.539-555
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• 2023

Although some prediction models have successfully developed for ultra-high performance concrete (UHPC), they do not provide insights and explicit relations between all constituents and its consistency, and compressive strength. In the present study, based on the experimental results, several mathematical models have been evaluated to predict the consistency and the 28-day compressive strength of UHPC. The models used were Linear, Logarithmic, Inverse, Power, Compound, Quadratic, Cubic, Mixed, Sinusoidal and Cosine equations. The applicability and accuracy of these models were investigated using experimental data, which were collected from literature. The comparisons between the models and the experimental results confirm that the majority of models give acceptable prediction with a high accuracy and trivial error rates, except Linear, Mixed, Sinusoidal and Cosine equations. The assessment of the models using numerical methods revealed that the Quadratic and Inverse equations based models provide the highest predictability of the compressive strength at 28 days and consistency, respectively. Hence, they can be used as a reliable tool in mixture design of the UHPC.

• Journal of the Institute of Electronics Engineers of Korea CI
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• 제48권3호
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• pp.54-68
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• 2011

As the prediction accuracy of conditional branch instruction is increased highly, the importance of prediction accuracy for unconditional branch instruction is also increased accordingly. Except the case of RAS(Return Address Stack) overflow, the prediction accuracy of function return address should be 100% theoretically. However, there exist some possibilities of miss-predictions for RAS return addresses, when miss-speculative execution paths are invalidated, in case of modern speculative microprocessor environments. In this paper, we propose the RAS rename technique to prevent RAS pollution, results in the reduction of RAS miss-prediction. We divide a RAS stack into a soft-stack and a hard-stack and we handle the instructions for speculative execution in the soft-stack. When some overwrites happen in the soft-stack, we move the soft-stack data into the hard-stack. In addition, we propose an enhanced version of RAS rename scheme. In simulation results, our solution provide 1/90 reduction of miss-prediction of function return address, results in up to 6.85% IPC improvement, compared to normal RAS method. Furthermore, it reduce miss-prediction ratio as 1/9, compared to previous technique.

• Advances in concrete construction
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• 제14권1호
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• pp.45-55
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• 2022

In this article, the flexural and shear capacity of ultra-high-performance fiber-reinforced concrete beams (UHPFRC) using two kinds of rebars, including GFRP and steel rebars, are experimentally investigated. For this purpose, six UHPFRC beams (250 × 300 × 1650 mm) with three reinforcement ratios (ρ) of 0.64, 1.05, and 1.45 were constructed using 2% steel fibers by volume. Half of the specimens were made of UHPFRC reinforced with GFRP rebars, while the other half were reinforced with conventional steel rebars. All specimens were tested to failure in four-point bending. Both the load-deformation at mid-span and the failure pattern were studied. The results showed that utilizing GFRP bars increases the flexural strength of UHPFRC beams in comparison to those made of steel bars, but at the same time, it reduces the post-cracking strain hardening. Furthermore, by increasing the percentage of longitudinal bars, both the post-cracking strain hardening and load-bearing capacity increase. Comparing the experiment results with some of the available equations and provisions cited in the valid design codes reveals that some of the equations to predict the flexural strength of UHPFRC beams reinforced with conventional steel and GFRP bars are reasonably conservative, while Khalil and Tayfur model is un-conservative. This issue makes it essential to modify the presented equations in this research for predicting the flexural strength of UHPFRC beams using GFRP bars.

• Journal of Intelligence and Information Systems
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• 제9권1호
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• pp.71-89
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• 2003

Although many studies demonstrate that one technique outperforms the others for a given data set, there is often no way to tell a priori which of these techniques will be most effective in the classification problems. Alternatively, it has been suggested that a better approach to classification problem might be to integrate several different forecasting techniques. This study proposes the linearly combining methodology of different classification techniques. The methodology is developed to find the optimal combining weight and compute the weighted-average of different techniques' outputs. The proposed methodology is represented as the form of mixed integer programming. The objective function of proposed combining methodology is to minimize total misclassification cost which is the weighted-sum of two types of misclassification. To simplify the problem solving process, cutoff value is fixed and threshold function is removed. The form of mixed integer programming is solved with the branch and bound methods. The result showed that proposed methodology classified more accurately than any of techniques individually did. It is confirmed that Proposed methodology Predicts significantly better than individual techniques and the other combining methods.

• Journal of Korean Society of Forest Science
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• 제99권2호
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• pp.204-212
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• 2010

This study was performed in 22 unthinned Larix olgensis plantations in northeast China. Data were collected on 95 sample trees of different canopy positions and the diameter at breast height ($d_{1.3}$) ranged from 5.7 cm to 40.2 cm. The individual tree models for the prediction of vertical distribution of live crown, branch and needle biomass were built. Our study showed that the crown, branch and needle biomass distributions were most in the location of 60% crown length. These results were also parallel to previous crown studies. The cumulative relative biomass of live crown, branch and needle were fitted by the sigmoid shape curve and the fitting results were quite well. Meanwhile, we developed the crown ratio and width models. Tree height was the most important predictor for crown ratio model. A negative competition factor, ccf and bas which reflected the effect of suppression on a tree, reduced the crown ratio estimates. The height-diameter ratio was a significant predictor. The higher the height-diameter ratio, the higher crown ratio is. Diameter at breast height is the strongest predictor in crown width model. The models can be used for the planning of harvesting operations, for the selection of feasible harvesting methods, and for the estimation of nutrient removals of different harvesting practices.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제7권4호
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• pp.26-33
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• 1993

The acoustic emission automatic detection system is developed to observe tree deterioration phenomena. Applying an alternating voltage of 15(kVnns) toXLPE tree specimens, many pulses of small amplitude are detected when the bush type tree developes branch type and a few pulses of high amplitude prcxluced as branch type propagated to bush type tree. Therefore, it is known that pulses having small amplitude operates as a destructive factor. It is observed that the skewness of the amplitude and the number of average pulses as distribution tendency of three dimension are characteristic quantity of AE pulses. As the trajectory of skewness is farther from the origin on the S-plane, it is more likely to breakdown.

• Steel and Composite Structures
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• 제35권2호
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• pp.215-235
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• 2020

Cracks and defects may occur anywhere in a plate under tension. Cracks can affect the buckling stability performance and even the failure mode of the plate. A search of the literature reveals that the reported research has mostly focused on the study of plates with central and small cracks. Considering the effectiveness of cracks on the buckling behavior of plates, this study intends to investigate the effects of some key parameters, i.e., crack size and location as well as the plate aspect ratio and support conditions, on the buckling behavior, stress intensity factor (SIF), and the failure mode (buckling or fracture) in cracked plates under tension. To this end, a sophisticated mathematical code was developed using MATLAB in the frame-work of extended finite element method (XFEM) in order to analyze the buckling stability and collapse of numerous plate models. The results and findings of this research endeavor show that, in addition to the plate aspect ratio and support conditions, careful consideration of the crack location and size can be quite effective in buckling behavior assessment and failure mode prediction as well as SIF evaluation of the cracked plates subjected to tensile loading.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제25권11B호
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• pp.1939-1947
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• 2000

본 논문에서는 명령어의 효율적인 페치를 위해 분기 타겟 주소 전체를 사용하지 않고 캐쉬 메모리(cache memory) 내의 적은 비트 수로 인덱싱 하여 한 클럭 사이클 안에 최대 4개의 명령어를 다음 파이프라인으로 보내줄 수 있는 방법을 제시한다. 본 프리페치 유닛은 크게 나누어 3개의 영역으로 나눌 수 있는데, 분기에 관련하여 미리 부분적으로 명령어를 디코드 하는 프리디코드(predecode) 블록, 타겟 주소(NTA : Next Target Address) 테이블 영역을 추가시킨 명령어 캐쉬(instruction cache) 블록, 전체 유닛을 제어하고 가상 주소를 관리하는 프리페치(prefetch) 블록으로 나누어진다. 사용된 명령어들은 SPARC(Scalable Processor ARChitecture) V9에 기준 하였고 구현은 Verilog-HDL(Hardwave Description Language)을 사용하여 기능 수준으로 기술되고 검증되었다. 구현된 프리페치 유닛은 명령어 흐름에 분기가 존재하더라도 단일 사이클 안에 4개까지의 명령어들을 정확한 예측 하에 다음 파이프라인으로 보내줄 수 있다. 또한 NTA를 사용한 방법은 같은 수의 레지스터 비트를 사용하였을 때 BTB(Branch Target Buffer)를 사용하는 방법과 비교하여 2배정도 많은 개수의 분기 명령 주소를 저장할 수 있는 장점이 있다.

• Proceedings of the Korean Information Science Society Conference
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• 한국정보과학회 2000년도 가을 학술발표논문집 Vol.27 No.2 (3)
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• pp.636-638
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• 2000

제어 독립성(Control Independence)은 슈퍼스칼라 프로세서에서 명령어 수준 병렬성(Instruction-Level Parallelism)을 향상시키기 위한 중요한 요소로 작용하고 있다. 분기 예상기법(Branch Prediction Mechanism)에서 잘못 예상될 경우에는 예상한 분기 방향의 명령어들을 제거하고 올바른 분기 방향의 명령어들을 다시 반입하여 수행해야 한다. 본 논문에서는 컴파일 시 프로파일링을 통한 정적인 방법과 프로그램상의 제어 흐름을 통해 동적으로 제어 독립적인 명령어를 탐지함으로써 분기 명령어의 잘못된 예상으로 인해 제거되는 명령어를 효과적으로 감소시켜 프로세서의 성능을 향상시키는 메커니즘을 제안한다. SPECint95 벤치마크 프로그램에 대해 기존의 방법과 본 논문에서 제안한 방법 사이의 사이클 당 수행된 명령어 수를 분석한 결과, 4-width 프로세서에서 4%~6%, 8-width 프로세서에서 11%~18%, 16-width 프로세서에서 15%~17%의 성능 향상을 보이고 있다.