Pattern-Search-Based Algorithm for Ground-Motion Selection with Targeted Mean and Standard Deviation

Gifari Zulkarnaen,주영규 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.4

Ground-motion selection is essential as an input for dynamic structural analyses. Although recent studies have highlighted the importance of target variance as auxiliary criteria and introduced selection methods, they typically require a trade-off between computational expense and accuracy. This paper presents an effi cient and accurate method for ground-motion selection and scaling that matches both the target mean and standard deviation, while using either a single-objective- or multi-objective-based pattern-search optimization technique. The selection algorithm was tested using the code-based and conditional-spectrum-based target spectrum for various design scenarios. The results indicated that the pattern-search-based selection algorithm is an optimal method as it provides the best-matching records suite with a more precise and quicker selection than other notable optimization techniques.

Fault-Line Selection Method for Small-Current Grounded System Based on Multi-classifier

Su Xianxin,Wei Hua,Wei Hongbo,Lyu Zhongliang,Zhang Xuan,Gao Wei 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

In a small-current grounded system, the fault characteristics are very obscure when a single-phase ground fault occurs; therefore, the faulty line must be selected to remove it. This paper proposes a fault-line selection (FLS) method based on multi-classifier, which transforms FLS into a multi-classification problem. It solves the problems in traditional methods, such as low accuracy and high equipment cost. Multi-classifiers based on denoising Autoencoder(DAE) are used to reduce the dimension of historical dispatching data and extract single-phase ground-fault features. Firstly, the dispatching data are preprocessed to eliminate useless data and fill in vacancies. Then, the fault segments are marked and labeled samples containing steady-state and transient information of single-phase ground faults are obtained. Finally, a multi-classifier based on DAE is built, and this model is trained with labeled fault samples to obtain a high-accuracy FLS model. The experiments show that the accuracy of the proposed method exceeds 97%, which is much better than other data-driven models and traditional methods. The proposed method has been operating for over two years in a real power system south of China. The excellent performance of the proposed method for FLS in practice and simulation indicates a vast application potential.

목표스펙트럼의 평균과 분산을 고려하기 위한 시뮬레이션 기반의 효율적인 지반운동기록 선정 알고리즘

석승욱,한상환,Seok, Seung-Wook,Han, Sang-Whan 대한건축학회 2012 대한건축학회논문집 Vol.28 No.2

Linear and nonlinear dynamic analyses become popular in seismic design and seismic performance evaluation procedures. The accuracy of the results of such analyses depends not only on accurate analytic model of structures but also a proper selection of input ground motions. The purpose of this study is to develop a computationally efficient and accurate algorithm for selecting ground motions considering the mean and variance of target response spectrum. The proposed algorithm adopts a simulation based process for generating a desired number ($=n_g$) of simulated response spectra using the Monte Carlo Simulation with information of the mean, variance, and correlation structure of target response spectrum. The accuracy of selecting ground motions using the proposed algorithm is improved by generating multiple (=100) sets of simulated response spectra. Ten sets are chosen from the 100 sets, which best match the mean and standard deviation of a target response spectrum. Ground motions are then selected for each of the top ten sets. The set of ground motions having the mean and standard deviation of their response spectra that best match the target response spectrum is the one to be selected. To verify the accuracy and efficiency of the algorithm, numerical examples are provided.

목표스펙트럼의 평균과 분산을 고려하기 위한 시뮬레이션 기반의 효율적인 지반운동기록 선정 알고리즘

석승욱(Seok Seung-Wook),한상환(Han Sang-Whan) 대한건축학회 2012 大韓建築學會論文集 : 構造系 Vol.28 No.2

Linear and nonlinear dynamic analyses become popular in seismic design and seismic performance evaluation procedures. The accuracy of the results of such analyses depends not only on accurate analytic model of structures but also a proper selection of input ground motions. The purpose of this study is to develop a computationally efficient and accurate algorithm for selecting ground motions considering the mean and variance of target response spectrum. The proposed algorithm adopts a simulation based process for generating a desired number (=ng) of simulated response spectra using the Monte Carlo Simulation with information of the mean, variance, and correlation structure of target response spectrum. The accuracy of selecting ground motions using the proposed algorithm is improved by generating multiple (=100) sets of simulated response spectra. Ten sets are chosen from the 100 sets, which best match the mean and standard deviation of a target response spectrum. Ground motions are then selected for each of the top ten sets. The set of ground motions having the mean and standard deviation of their response spectra that best match the target response spectrum is the one to be selected. To verify the accuracy and efficiency of the algorithm, numerical examples are provided.

A multi-time scale vibration surveillance system for third-party threats on urban pipeline

Zelong Liu,Renzhu Peng,Yan Zhang,Suzhen Li 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.3

Third-party interference caused by construction activities have seriously jeopardized the security of underground pipelines. Following the process of "signal collection—feature extraction and selection—multi-time scale identifying— combining results by voting", this paper proposes a multi-time scale surveillance system for interference prevention of thirdparty threats on the nearby pipeline by using ground vibration monitors. The system focuses on the two major urban construction activities induced by excavator breaking hammers and road cutters, and presents excellent performance under the noise of traffic and pedestrian. Three features including the short-time zero-crossing rate, subset differential parameter and the Mel frequency cepstrum coefficients are selected by the analysis of the maximal information coefficient and feature importance for identifying the patterns of different third-party activities. The crucial part of the surveillance system consists of the two random forest-based classifiers trained by 0.5 s samples and 8 s samples respectively, and the alarm depends on the voting of the two classifiers, which brings the perspectives on different time scales for decision making. In the test, 96.14% of the threat vibration signals can be detected, while only 0.45% of the environmental noise signals cause false alarms.

Application of grinding kinetics analysis of inorganic powders by a stirred ball mill

최희규,Woong Lee,Seongsoo Kim,황진연 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6

The need for ultra fine particles has been increasing in the preparation field of raw powders such as fine ceramics and high functional products. A series of wet grinding experiments were carried out on inorganic powders such as calcite, pyrophyllite and talc by a stirred ball mill. The grinding rate constant K’ in the equation of grinding kinetics was examined based on the grinding kinetics analysis as the same type of function of a previous paper on a vertical type planetary ball mill. The experimental particle size distribution of the ground products was obtained in various grinding conditions. The grinding rate constants K and K' were expressed by empirical equation involving experimental conditions by a stirred ball mill. The empirical equation on the grinding rate constant was expressed in terms of a function involving the ball diameter of grinding balls, the median diameter of feed material, and Bond’s work index of material, in the experimental conditions. The values of empirical constants C1 and C2 were 21.13 and 0.0109 on K, while C1 and C2 were 120.99 and 0.0192 on K', respectively. And the particle size distribution of ground products of each test material for a given grinding time was found to be expressing the selection function (the specific rate of breakage) which was obtained from the grinding kinetics analysis. In this study, the grinding rate change on calcite and pyrophyllite was similar at the same experimental operation condition. However, in the case of talc, it was observed that the grinding rate was not increased compared with other samples.

건식정제에 의한 견운모광의 품위향상연구

조건준,김윤종,박현혜,조성백,Cho, Keon-Joon,Kim, Yun-Jong,Park, Hyun-Hae,Cho, Sung-Baek 한국재료학회 2009 한국재료학회지 Vol.19 No.4

A study on the dry beneficiation of sericite occurring in the Daehyun Mine of the Republic of Korea region as performed by applying selective grinding and air classification techniques. Quartz and sericite occurred in the raw ore as major components. The results of liberation using a ball mill and an impact mill showed that the contents of $R_2O$ were increased while $SiO_2$ was decreased in proportion to decreasing particle size. According to the XRD, XRF analysis and the EDS of SEM analysis, the ball mill gave a better grade product in $R_2O$ content than the impact mill when the particle size was the same. When the raw ore was ground by the impact mill with arotor speed 57.6 m/sec and then followed by 15,000rpm classification using an air classifier, the chemical composition of the over flowed product was 49.65wt% $SiO_2$, 32.15wt% $Al_2O_3$, 0.13wt% $Fe_2O_3$, 10.37wt% $K_2O$, and 0.14wt% $Na_2O$. This result indicates that the $R_2O$ contents were increased by 49.5% compared to that of the raw ore. From these results described above, it is suggested that hard mineral such as Quartz little ground by selective grinding using impact mill whereas soft mineral such as sericite easily ground to small size. As a result of that hard minerals can be easily removed from the finely ground sericite by air classification and the $R_2O$ grade of thus obtained concentrate was improved to higher than 10wt% which can be used for ceramics raw materials.

목표스펙트럼에 근사한 평균응답스펙트럼을 갖는 지반운동집단의 효율적인 선정방법

한상환,석승욱 한국지진공학회 2011 한국지진공학회논문집 Vol.15 No.5

본 연구에서는 지반운동 라이브러리에서 목표스펙트럼에 근사한 평균응답스펙트럼을 갖는 한 개 혹은 다수의 지반운동을 선정하는 효율적인 방법을 제안하고자 한다. 지반운동 선정 시 목표스펙트럼의 형상과 크기를 맞추어야 하는데 이 두 가지를 독립적으로 고려할 수 있다는 기존 연구결과에 따라 본 연구에서도 형상이 가장 유사한 지반운동을 찾고 크기를 맞추기 위하여 배율조정계수를 사용한다. 형상을 맞추기 위해 각 주기에서 목표스펙트럼과 지반운동 평균응답스펙트럼의 차이 값의 표준편차가 최소가 되도록 하여 선정하는 방법을 제안하였다. 형상이 결정된 후 그 크기를 맞추기 위해 본 연구에서 제안한 배율조정계수를 찾는 방법은 기존 연구와 달리 한번에 찾을 수 있도록 제안하였다. 40개의 지반운동 라이브러리로부터 제안한 방법을 이용하여 목표스펙트럼에 근사한 평균스펙트럼을 갖는 7개의 지반운동기록을 선정한 결과, 그 정확성과 계산소요시간에 있어 모두 만족할만한 결과를 보였다. This paper proposes an efficient method for selecting ground motions with the mean response spectrum matching a target spectrum. Since former studies reported that the shape and amplitude of the response spectra can be treated independently for selecting ground motions, this study first selects ground motions such that the shape of their mean response spectrum matches that of the target spectrum, then scales the ground motions. To select the ground motions best matching the shape of the target response spectrum, the standard deviation of the difference between the target response spectrum and the mean response spectrum of the selected ground motions needs to be minimized. Unlike the existing procedure, the scaling factor can be computed without iteration. Based on the selection results of 7 ground motions from a library of 40 ground motions, the proposed method is verified as an accurate and efficient method.

선택분쇄 및 공기분급에 의한 일라이트의 정제기술 연구

김상배,조성백,김완태,윤성대 한국광물학회 2005 광물과 암석 (J.Miner.Soc.Korea) Vol.18 No.1

선택분쇄 및 분급 기술에 의한 영동지역에 산출하는 일라이트에 대한 정제연구를 수행하였다. 원광의 주 구성광물은 석영과 일라이트이며, 황철석과 섬아연석, 황동석 등과 같은 황화광물들 이 소량 수반된다. 습식 해쇄 후 체가름 결과, 미립자로 갈수록 Al₂O₃, K₂O 함량 및 강열감량은 높아지며, SiO₂함량은 낮아졌으며, Fe₂O₃의 함량은 굵은 입자가 다소 낮았으나 입도에 관계없이 비교적 균일하게 나타났다. 단체분리를 위한 충격식 분쇄기의 분쇄매체의 선속도가 증가함에 따라 미립자 생성율은 증가되었으며, 분급과정에서의 미립자 회수율 역시 증가되었다. 분쇄매체의 선속도를 57.6 m/sec로 조절하여 선택분쇄 후 최적의 조건으로 분급하면 정제산물을 76.16 wt% 정도 생산할 수 있었다. 정제산물의 화학조성은 SiO₂70.13%, Al₂O₃19.40%, Fe₂O₃ 1.62%, K₂O 5.20%, 1g.loss 2.77%이었다. 본 연구에서 사용한 정제공정은 비금속 광물의 정제와 입도조절 공정을 동시에 행할 수 있는 유용한 기술임을 알 수 있었다. A study on the beneficiation of illite occurring in Youngdong province is performed with applying selective grinding and air classification techniques. Quartz and illite are occurred as major components, and sulfide minerals such as pyrite, chalcopyrite are associated as minor components. The result of sieving test shows that contents of Al₂O₃, K₂O and ignition loss are increased, whereas SiO₂is decreased with particle size decrease. Fe₂O₃content is almost same in all the particle size range but slightly lower at coarse particles. The yield of fine particles is increased with increasing rotor speed in both grinding stage and air classification stage. When the selective grinding and air classification are carried out at optimal condition, yield of the concentrate is 76.16 wt.%. The chemical compositions of the concentrate are SiO₂70.13%, Al₂O₃19.40%, Fe₂O₃ 1.62%, K₂O 5.20% and ignition loss 2.77%. The beneficiation process developed in the current study is very effective method which purification and particle size control can be achieved simultaneously.

교반 볼밀에 의한 방해석, 납석, 활석의 분쇄 시 분쇄속도론에 관한 연구 - 선택함수의 고찰

최희규 ( Hee Kyu Choi ),김성수 ( Seong Soo Kim ),황진연 ( Jin Yeon Hwang ) 한국광물학회 2007 광물과 암석 (J.Miner.Soc.Korea) Vol.20 No.2