• Steel and Composite Structures
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• v.28 no.5
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• pp.517-525
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• 2018

The specimens made by Z2CND18.12N austenitic stainless steel were conducted on a 100 kN closed loop servo hydraulic tension-compression testing machine with a digital controller. Uniaxial tension and uniaxial ratcheting effect tests were carried out at $25^{\circ}C$. Moreover, Uniaxial tension tests were conducted at $150^{\circ}C$, $250^{\circ}C$ and $350^{\circ}C$. Based on these experimental data, the prediction models of stress-strain curve and the relationship of ratcheting strain and number of cycles were established by the algorithm principle of BP neural network. The results indicated that the predicted results of neural network model were in well agreement with experimental data. It was found that the BP neural network model had high validity and accuracy.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.4
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• pp.57-66
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• 2012

When typical Z-source DC/AC inverter(ZSI) is operated in high voltage gain area, because of its high duty ratio, voltage and current stress in Z-network of typical ZSI are increased. This paper proposes a new switched trans ZSI(STZSI) with two switched trans cells which consist of one trans and two diodes. To confirm the operation performance of the proposed system, the PSIM simulation is performed for typical ZSI, switched inductor ZSI and the proposed STZSI. Voltage / current stress and transient state characteristics of each method are compared under the condition of DC input voltage 100[V] and output phase voltage 66[Vrms]. As a result, we confirmed that transient state of the proposed STZSI is short compared with the conventional ZSI because the high voltage gain is obtained using the same duty ratio, also a low duty ratio is required for the same output voltage. Finally, we could know the proposed system have low voltage and current stress in Z-network compared with the conventional ZSI.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.1996-2005
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• 2010

This paper proposes a new method for constant control of the output AC voltage of a voltage-fed three phase Z-source inverter (ZSI), in case of Z-network DC voltage variation or heavy change of load. The modulation index for the reference output AC voltage of ZSI can be calculated by the basic definition of ZSI, the input DC voltage and capacitor voltage of Z-network. And, the output AC voltage of ZSI is controlled by the modified space vector modulation (SVM) with the calculated modulation index. By the proposed method, the modulation index of output AC voltage is closely following in the reference modulation index. The validity of the proposed method is verified using PSIM simulation. In case which the input DC voltage of ZSI is heavily changed from 100[V] to 70[V] (or to 150[V]) and in case which load is changed from $30[\Omega]$ to $10[\Omega]$, we confirmed that the output AC voltage of ZSI is constantly controlled by the proposed method because the modulation index of ZSI is also simultaneously changed. Finally, FFT and %THD of the output voltage and current of ZSI by the proposed method are analyzed.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.98-104
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• 2012

This paper presents a novel transformer isolated parallel connected full-bridge dc-dc converter using recently developed trans-Z-source network. Unlike the traditional voltage -fed or current-fed converters, the proposed converter can be open- and short-circuited without damaging switching devices. Therefore, the desired buck and boost function can be achieved and the converter reliability can be greatly improved. A 6 kW prototype dc-dc converter is built and tested to verify performances of the proposed converter.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.2
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• pp.356-375
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• 2021

The Generation Z (Gen-Z) consumer has a unique beauty-consuming behavior that is distinct from the previous generations. This study aims to identify the meaning of makeup rituals based on the theoretical framework of the ritual concept. In-depth interviews were conducted with fifteen females in their mid-teens to early 20s. The results showed that Gen-Z has different types of makeup ritual scripts for both ordinary days and special days, which are constantly being re-written and revised based on the experience accumulated. In addition, there are various types of ritual artifacts that play an important role in Gen-Z's makeup ritual, and that they provide psychological comfort and satisfaction. The importance of DIY (Do It Yourself), collecting, and independent brands is emphasized. The role of Gen-Z in the makeup ritual was expanding from a creator for her own ritual to a collaborator for peers' rituals, and sometimes the expansion goes beyond the direct relationships to virtual ones through SNS (Social Network Service). The Gen-Z cohort is found to be a member of beauty knowledge network through which they learn, share, and create the know-how and shopping skills.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.145-146
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• 2006

The recent power systems are very complex and to model them completely is impractical for analysis of electromagnetic transient. Therefore areas outside the immediate area of interest must be represented by some form of Frequency Dependent Network Equivalent (FDNE). In this paper a method for developing Frequency Dependent Network Equivalent (FDNE) using Z-domain rational Function Fitting is presented and demonstrated. The FDNE is generated by Linearized Least Squares Fitting(LSF) of the frequency response of a Z-domain formulation. This Three-port FDNE have been applied to the test AC power system. The electromagnetic transient package PSCAD/EMTDC is used to assess the transient response of the Three-port FDNE developed under different condition. The study results have indicated the robustness and accuracy of Three-port FDNE for analisys of electromagnetic transient and harmonic assessment.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.453-460
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• 2012

This paper proposes the method to design the parameters of an impedance network at three-phase QZSI(quasi Z-source inverter) by considering an equivalent series resistance (ESR) in the capacitor. The equations of both two capacitor voltages and two inductor currents are derived at three operating modes of the QZSI. The capacitor voltage ripples caused by the ESR in the capacitor at the transition state of operating modes are calculated. Based on the ripples of both the capacitor voltages and inductor currents, the optimal values of capacitor and inductor are designed. The simulation studies using PSIM and experimental results with DSP are carried out to verify the performance of design method.

• Geomechanics and Engineering
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• v.30 no.3
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• pp.273-280
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• 2022

A certain amount of random vibration excitation to subway track is caused by subway operation. This excitation is transmitted through track foundation, tunnel, soil medium, and ground building to the ground and ground structure, causing vibration. The vibration affects ground building. In this study, the results of ANSYS numerical simulation was used to establish back-propagation (BP) neural network model. Moreover, a back-propagation neural network model consisting of five input neurons, one hidden layer, 11 hidden-layer neurons, and three output neurons was used to analyze and calculate the vertical Z-vibration level of New Capital's ground buildings of Qingdao Metro phase I Project (Line M3). The Z-vibration level under different working conditions was calculated from monolithic roadbed, steel-spring floating slab roadbed, and rubber-pad floating slab roadbed under the working condition of center point of 0-100 m. The steel-spring floating slab roadbed was used in the New Capital area to monitor the subway operation vibration in this area. Comparing the monitoring and prediction results, it was found that the prediction results have a good linear relationship with lower error. The research results have good reference and guiding significance for predicting vibration caused by subway operation.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.512-515
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• 2006

일반적으로 연료전지 Z-소스 액티브 필터는 고조파 보상전류가 급변하는 경우, 연료전지의 특성에 기인하여 Z-소스 네트워크의 전압이 강하하는 현상이 발생한다. 본 연구에서는 이상의 문제점을 개선하기위한 Z-소스 네트워크의 전압강하 보상기능을 갖는 Z-소스 액티브 필터를 제안하였다. Z-소스 네트워크의 전압보상을 위하여 절연형 Cuk 컨버터가 사용되었다. PSIM을 이용하여 부하 급변의 과도상태에서 제안된 방법의 타당성이 입증되었다.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.223-226
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• 2007

본 연구에서는 Z-소스 네트워크를 갖는 능동전력필터 시스템을 제안하였다. 제안된 방식의 동작원리는 종전의 V-소스 능동전력필터와 동일하나, 고조파 보상 전류가 Z-소스 인버터에 의하여 발생된다는 점이 차이가 있다. 또 제안된 시스템을 서로 병렬 운전하는 경우와 종전의 능동전력필터와 병렬 운전하는 방법을 제안하였다. 제안된 시스템은 PSIM 시뮬레이션에 의하여 타당성이 입증되었다.