• 전산구조공학
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• 제2권3호
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• pp.85-95
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• 1989

본 논문에서는 Rayleigh파, 전단파 및 압축파의 영향을 동시에 해석할 수 있는 주파수 종속 무한요소와 이를 이용한 지반-구조물의 동적상호작용의 해석법에 대하여 연구하였다. 방사적으로 전파되는 응력파의 성분에 대한 무한요소와 아울러 매립(Embedded)기초나 적층(Layered)지반을 해석하기 위하여 수평으로 전파되는 파를 해석할 수 있는 무한요소를 개발하였고, 요소행렬 구성하기 위한 적분시 하나의 파성분만 존재하는 경우에 대하여 효율적으로 적용되었던 Newton Cotes 적분과 유사한 방법을 Multi-Waves 문제에 알맞게 확장 적용하였다. 이 방법의 타당성은 반무한, 균질 지만의 위에 놓여있는 원형강판과 지반에 묻혀 있는 원통형 강체기초의 Compliance 함수를 구하여 기존의 문헌에 발표된 값과 비교함으로써 검증하였다. 예제해석은 지진하중을 받는 원자력발전소 격납구조를 대상으로 하여 수행하였으며, 매립깊이의 크기, 지반의 재료감쇠 및 지반의 모형기법에 따른 구조물-지반의 상호작용의 해석결과를 비교 분석하였다.

• 드라이브 ㆍ 컨트롤
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• 제15권2호
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• pp.1-8
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• 2018

This study is a first step toward reducing surge pressure, and it has another purpose, which is to developing an analysis model which can closely analyze a hydraulic circuit and be used in design. For development of analysis model, SimulationX, a commercial program, is used. The study progress methods are as follows. By analyzing the structure and operating mechanisms of each part of the hydraulic system of the pump truck and referring its parameters, develop a single component model. Assemble the developed single component model, and make an overall analysis the model. By comparing the similarities between the developed model and the actual system's test results, validate the reliability of the analysis model.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.3166-3175
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• 2022

The most numerical investigations of the thermal-hydraulic phenomena following the loss of the residual heat removal capability during the mid-loop operation of the pressurized water reactor were performed according to simplifications and are not sufficiently accurate. To perform more accurate and more reliable predictions of thermal-hydraulic accidents in a nuclear power plant using computational fluid dynamics codes, a more detailed methodology is needed. Modelling results identified that thermal stratification and natural convection are observed. Temperatures of lower monitoring points remain low, while temperatures of upper monitoring points increase over time. The water in the heated region, in the upper unheated region and the pipe region was well mixed due to natural convection, meanwhile, there is no natural convection in the lower unheated region. Water temperature in the pipe region increased after a certain time delay due to circulation of flow induced by natural convection in the heated and upper unheated regions. The modelling results correspond to the experimental data. The developed computational fluid dynamics methodology could be applied for modelling of two-component single/two-phase natural convection and thermal stratification phenomena during the mid-loop operation of the pressurized water reactor or other nuclear and non-nuclear installations at similar conditions.

• Smart Structures and Systems
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• 제31권4호
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• pp.383-392
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• 2023

Post-earthquake building condition assessment is crucial for subsequent rescue and remediation and can be automated by emerging computer vision and deep learning technologies. This study is based on an endeavour for the 2nd International Competition of Structural Health Monitoring (IC-SHM 2021). The task package includes five image segmentation objectives - defects (crack/spall/rebar exposure), structural component, and damage state. The structural component and damage state tasks are identified as the priority that can form actionable decisions. A multi-task Convolutional Neural Network (CNN) is proposed to conduct the two major tasks simultaneously. The rest 3 sub-tasks (spall/crack/rebar exposure) were incorporated as auxiliary tasks. By synchronously learning defect information (spall/crack/rebar exposure), the multi-task CNN model outperforms the counterpart single-task models in recognizing structural components and estimating damage states. Particularly, the pixel-level damage state estimation witnesses a mIoU (mean intersection over union) improvement from 0.5855 to 0.6374. For the defect detection tasks, rebar exposure is omitted due to the extremely biased sample distribution. The segmentations of crack and spall are automated by single-task U-Net but with extra efforts to resample the provided data. The segmentation of small objects (spall and crack) benefits from the resampling method, with a substantial IoU increment of nearly 10%.

• The Journal of the Acoustical Society of Korea
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• 제21권4E호
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• pp.146-155
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• 2002

We present a new technique for achieving source separation when given only a single charmel recording. The main idea is based on exploiting the inherent time structure of sound sources by learning a priori sets of time-domain basis functions that encode the sources in a statistically efficient manner. We derive a learning algorithm using a maximum likelihood approach given the observed single charmel data and sets of basis functions. For each time point we infer the source parameters and their contribution factors. This inference is possible due to the prior knowledge of the basis functions and the associated coefficient densities. A flexible model for density estimation allows accurate modeling of the observation, and our experimental results exhibit a high level of separation performance for simulated mixtures as well as real environment recordings employing mixtures of two different sources. We show separation results of two music signals as well as the separation of two voice signals.

• 지질공학
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• 제5권3호
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• pp.331-337
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• 1995

3성분 단일 지진 관측의 방위각 결정에서 때때로 결과는 파형에 의존하고, 자동 관측은 불편하게 만든다. 본 연구에서는 시간-방향 스태킹 기술에 의해서 방위각이 아주 긴 파열(wave train) 관측으로부터 더 정확한게 결정되는 대안을 제안한다. 한반도 지진관측으로 취득한 디지털 파형을 가지고 시험한 결과 단순한 알고리즘은 광역거리에서 지진 진원의 방위각을 더 정확하게 결정하여 주는 것을 보여준다.

• BMB Reports
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• 제48권12호
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• pp.643-644
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• 2015

In eukaryotes, small RNAs play important roles in both gene regulation and resistance to viral infection. Argonaute proteins have been identified as a key component of the effector complexes of various RNA-silencing pathways, but the mechanistic roles of Argonaute proteins in these pathways are not clearly understood. To address this question, we performed single-molecule fluorescence experiments using an RNA-induced silencing complex (core-RISC) composed of a small RNA and human Argonaute 2. We found that target binding of core-RISC starts at the seed region of the guide RNA. After target binding, four distinct reactions followed: target cleavage, transient binding, stable binding, and Argonaute unloading. Target cleavage required extensive sequence complementarity and accelerated core-RISC dissociation for recycling. In contrast, the stable binding of core-RISC to target RNAs required seed-match only, suggesting a potential explanation for the seed-match rule of microRNA (miRNA) target selection.

• Journal of Power Electronics
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• 제18권4호
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• pp.997-1006
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• 2018

This paper proposes a transformerless photovoltaic (PV) power converter system based on the DC/AC boost inverter, which can solve the leakage current and second-order ripple power issues in single-phase grid-connected PV inverters. In the proposed topology, the leakage current can be decreased remarkably since most of the common-mode currents flow through the output capacitor, by-passing parasitic capacitors, and grounding resistors. In addition, the inherent ripple power component in the single-phase grid inverter can be suppressed without adding any extra components. Therefore, bulky electrolytic capacitors can be replaced by small film capacitors. The effectiveness of the proposed topology has been verified by simulation and experimental results for a 1-kW PV PCS.

• Steel and Composite Structures
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• 제2권4호
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• pp.277-296
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• 2002

A research investigation of single bolt lap-plate connection load-deformation behavior is presented. Each important characteristic of this behavior is evaluated and two methods for analytically approximating the behavior are developed and presented. The first of these methods is a component method in which the behavior of the connection is modeled as a combination of the behavior of the parts. The second method utilizes a number of parametric relationships that relate the connection parameters to coefficients of two non-linear continuous analytical curves. The test results from four independent experimental programs that investigated the behavior of single bolt lap-plate connections are used in the development and verification of these methods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1182-1194
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• 2016

The single image dehazing algorithm in existence can satisfy the demand only for improving either the effectiveness or efficiency. In order to solve the problem, a novel variational framework for single image dehazing based on restoration is proposed. Firstly, the initial atmospheric scattering model is transformed to meet the kimmel's Retinex variational model. Then, the green light component of image is considered as an input of the variational framework, which is generated by the sensitivity of green wavelength. Finally, the atmospheric transmission map is achieved by multi-resolution pyramid reduction to improve the visual effect of the results. Experimental results demonstrate that the proposed method can remove haze effectively with less memory consumption.