Numerical simulation and experiments of magnetic flux leakage inspection in pipeline steel

Xun-Bo Li,Xiang Li,Liang Chen,Pei-Fu Feng,Hai-Dong Wang,Zuo-Ying Huang 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.1

The magnetic flux leakage (MFL) method is currently the most commonly used pipeline inspection technique. In this paper, numerical simulation and experimental investigation on defect inspection in pipeline steel using MFL were carried out. In theoretical analysis, typical three-dimensional (3D) defects were accurately modeled and detailed MFL signals in the test surface were calculated by 3D finite element method (FEM). To confirm the 3D FEM results, different artificial defects were made and the MFL experiments were performed. The experimental study demonstrated that the results were agreement with the 3D FEM result. The results show that the 3D FEM is an effective analysis method for pipeline steel MFL inspection.

Improved Preimplantation Development of Cloned Porcine Embryos through Supplementation of Histone Deacetylase Inhibitor MS-275

Xun Fang,Ahmad Yar Qamar,신상태,조종기 한국임상수의학회 2019 한국임상수의학회지 Vol.36 No.5

The objective of this study was to analyse the effects of MS-275 (Class I and II histone deacetylase inhibitor) supplementation on the development of porcine in-vitro somatic nuclear transfer embryo production. During in-vitro development, early embryos were exposed to different concentrations of MS-275 (0, 5 μM, 10 μM, and 20 μM). In in-vitro culture supplemented group, the blastocyst development rate was significantly enhanced by 10 μM concentration than other groups (24.0% vs. 19.3%, 21.8%, 11.5%; P < 0.05). Additionally, the 6 h supplementation group, significantly improved the blastocysts production than 24 h, 48 h and control groups (26.1% vs. 17.0%, 15.2%, 2.8%; P < 0.05). Following supplementation with optimal concentrations and time (10 μM-6 h group), the blastocyst production was significantly higher than control (25.7% vs 15.8%; P < 0.05). The optimal concentrations of MS-275 significantly enhanced the percentages of ICM:TE than control (43.6% vs. 38.4%; P < 0.05) accompanied with significantly higher expression levels of reprogramming related genes (POU5F1, Naong, and SOX2). In conclusion, the optimal concentrations of 10 μM MS-275 and 6 h supplementation during in-vitro culture can significantly improve the quality of porcine in-vitro somatic nuclear transfer embryos through histone acetylation and epigenetic modification. Increasing the efficiency of clonal animal production will greatly promote the development of animal disease models and xenotransplantation.

Development Of Active Vibration Isolation System Using Fuzzy Method

Xun Yang(양손),Chae-Hun An(안채헌),Kyoung-Bog Jin(진경복),Kyung-Hwa Rim(임경화) 한국소음진동공학회 2007 한국소음진동공학회 학술대회논문집 Vol.2007 No.11

Fuzzy Controller Design for Active Vibration Isolation System Using Air-spring

Xun Yang(양손),Chae-Hun An(안채헌),Kyong-Bok Jin(진경복),Kyung-Hwa Rim(임경화) 한국소음진동공학회 2007 한국소음진동공학회 학술대회논문집 Vol.2007 No.3

차분 선부호화 구조를 적용한 LTE-A 상향링크 시스템의 성능 분석

Xun Li,박노윤(Noe Yoon Park),김영주(Young Ju Kim) 大韓電子工學會 2012 電子工學會論文誌-TC (Telecommunications) Vol.49 No.5

LTE 시스템에서는 폐회로 기반의 다중 안테나 기술이 적용되었으며, 차분 코드북을 비롯한 다양한 다중 안테나 기반의 선부호화 기술들이 향상된 LTE (LTE-Advanced) 시스템의 요구조건을 만족시키기 위해 제안되었다. 차분 코드북 설계와 관련하여 이전에 연구된 내용은 준 대각(quasi-diagonal) 단위 행렬 및 구면 캡(spherical cap)에 중점을 두었지만, 이는 동 이득 성질을 만족하지 못한다. 동 이득 성질은 특히 상향 링크에서 첨두 전력 대 평균 전력비 (PAPR)에 상당한 영향을 미치므로 매우 중요하다. 본 논문에서는 각 송신 안테나에 동 이득을 유지하는 성질을 이용한 새로운 차분 코드북을 상향 링크 기반 차분 선부호화 시스템에 적용하고, 이를 통해 비트 오류율(BER)과 첨두 전력 대 평균 전력비를 분석하였다. 특히, 송신기의 비선형 증폭기를 고려하여 다양한 차분 선부호화 기법들의 성능을 분석하였다. 모의 실험을 통해 선형 증폭기를 고려할 경우 기존에 제안된 차분 코드북이 우수한 성능을 보이지만, 비선형 증폭기를 고려할 경우에는 제안하는 차분 코드북의 우수함을 증명하였다. The closed-loop multiple-input multiple-output (MIMO) system has been adopted by long term evolution (LTE) system. Many techniques are proposed to enhance the transmission of LTE's advanced version to meet the increasing requirement, in which differential codebook gains a lot of interest. Previous researches on designing differential codebooks focused on quasi-diagonal unitary matrix which cannot guarantee the equal gain property. The equal gain property is very important to uplink because the performance of uplink is very sensitive to the peak-to-average power ratio (PAPR). In this paper, we derive the analytical expression of average bit error rate and PAPR for differential precoding MIMO system. Using the analytical results, we investigate the performances of several differential precoding schemes considering non-linear amplifier at the transmitter. Some selected simulation results indicate that the conventional differential precoding schemes have good performances without the consideration of non-linear amplifier. While considering non-linear amplifier, the proposed differential codebook outperforms other differential precoding schemes because it maintains the equal gain per transmit antenna.

Comprehensive CM Filter Design to Suppress Conducted EMI for SiC-JFET Motor Drives

Xun Gong,Ivan Josifovic,J.A. Ferreira 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper proposes a comprehensive EMI common-mode (CM) filter design procedure to suppress conducted EMI in silicon carbide (SiC) JFETs based inverter-fed motor drive systems. The first part of this paper is focusing on analyzing the EMC issue arisen from the newly generated power semiconductor device - SiC JFET, where the switching dynamics of SiC JFET and Si IGBT with the same power flowing level are compared. Then the second part towards EMI suppression for the inverter prototype. A comprehensive EMI CM filter design procedure is proposed. The proposed CM equivalent circuit model is able to evaluate the filter insertion loss gains over the whole conducted EMI frequency range, thereby different filter topologies can be compared and optimally selected. The performed experiments form the guideline that exhibits the process how the generated conducted EMI from the built inverter prototype is successfully suppressed to comply with the IEC61800-3 standard step by step.

Differential Precoding Algorithm for Noisy Feedback Channels

Xun Li(이신),Park Noe Yoon(박노윤),Kim Young Ju(김영주) 한국통신학회 2012 한국통신학회 학술대회논문집 Vol.2012 No.2

A Unifi ed Theory for Distortion Analysis of Thin-Walled Hollow Sections

Xun Xu,Huawen Ye,De-Yi Zhang,Shizhong Qiang 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.3

A novel unifi ed theory for distortion analysis of thin-walled hollow section has been proposed based on the Hellinger– Reissner variational principle to account for distortional shear deformation eff ects. Based on the proposed theory, a fi nite segment model has been developed and the method for determining the distortion functions of the cross-section has been proposed. The rationality of approaches for determining distortional shear stress has been analysed and it is concluded that Bredt’s pure distortion does not exist in the single-cell hollow section. Comparisons and analyses have been performed between the proposed theoretical model and the existing four groups of theories in distortion analysis of thin-walled hollow section. Eff ects of distortional warping shear stress on the shear deformation has been investigated and the results indicate that the distortional shear deformation eff ect results in a decrease of the distortional warping stresses and shear stresses but an increase of the transverse bending stresses. The numerical study indicates that the distortional shear deformation eff ects can be ignored and the fi rst derivative of the distortion angle can be employed as the distortional warping function for the conventional hollow sections of bridge structures.

Effects of gas flow on particulate deposition in EGR coolers

Xun Zhang,Jihui Li,Zhiqiang Han,Xunshun Wu,Wei Tian 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1

This paper presents the test approach to investigate the effects of gas flow rate on particulate deposition inside the exhaust gas recirculation (EGR) coolers. The tests were carried out on a diesel engine equipped with the EGR cooler that a given total gas flow rate passed through and that contained pluggable exchanger tubes to adjust the flow rate in the tubes. Test results show that under the given coolant temperature and EGR gas temperature, the lower flow rate in the exchanger tube is and the longer tubes are, the more particulate with D p > 50 nm deposit in the cooler. With the given total gas flow rate passing through the cooler, the lower flow rate in the exchanger tube is and the longer tubes are, the larger deposit mass is inside the cooler. In the cases of longer tubes, the effects of gas flow rate on the deposit mass are depends on the effects of gas velocity on the particulate deposition, rather than the effects of flow rate on the particulate number passing through the heat exchanger tube per minute.

Audio Fragment Identification System

Xun Jin,Jongweon Kim 보안공학연구지원센터 2014 International Journal of Multimedia and Ubiquitous Vol.9 No.12

Audio identification technologies are becoming of increasing interest for copyright protection and digital forensic. In this paper, we propose an audio fragment identification system for efficient audio identifying applications in practice. To identify an audio file fragment, we have to decode it according to its format. Thus, we precede format classification of audio fragment using Support Vector Machine in advance. After identify the format, fragment recovery is implemented by adding a maximum similar frame header in front of the fragment. Then we extract a chroma feature from the decoded audio data to achieve audio identification. The experimental results show the evaluations of the format classification, fragment recovery and audio identification.