• 전기학회논문지
• /
• 제60권8호
• /
• pp.1515-1522
• /
• 2011

This paper proposes the algorithm for the output AC voltage control of Z-source inverter by the detection of the input DC voltage and Z-network capacitor voltage. The actual modulation index of the proposed method is detected by the capacitor voltage in Z-network and input DC voltage of three-phase Z-source inverter. Control modulation index for the output voltage control is calculated by the detected actual modulation index and reference modulation index. And, calculated control modulation index is applied to the modified space vector modulation (SVM) for control the output voltage of Z-source inverter. To verify the validity of the proposed method, PSIM simulation was achieved and a DSP controlled 1[kW] three-phase Z-source inverter was producted. The simulation and experiment were performed under the condition that the load was changed in case of the constant input DC voltage and the input DC voltage was changed in case of the load was constant. As a result, we could know that the output phase voltage of Z-source inverter followed to the reference voltage 70[VRMS] despite the load or the input DC voltage were suddenly changed.

• 전기학회논문지
• /
• 제59권11호
• /
• pp.1996-2005
• /
• 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 applied mathematics & informatics
• /
• 제28권3_4호
• /
• pp.553-568
• /
• 2010

By making use of minimax theory and pseudo $Z_p$ index theory, some results on the existence and multiplicity of periodic solutions with minimal period to nonconvex superquadratic discrete Hamiltonian systems are obtained.

• 한국안전학회지
• /
• 제20권3호
• /
• pp.64-70
• /
• 2005

In this literature, fault detection and classification of faulty induction motors are carried out through Z-index and frequency analysis. Above frequency analysis refer Fourier transformation and Wavelet transformation. Z-index is defined as the similar form of energy function, also the faulty and healthy conditions are classified through Z-index. For the detection and classification feature extraction for the fault detection of an induction motor is carried out using the information from stator current. Fourier and Wavelet transforms are applied to detect the characteristics under the healthy and various faulty conditions. We can obtain feature vectors from two transformations, and the results illustrate that the feature vectors are complementary each other.

• 대한수학회지
• /
• 제35권4호
• /
• pp.891-901
• /
• 1998

We give a definition of the vector-valued index for Z-actions extending the numerical index in [9] and prove the extension theorem for Z-actions for showing basic properties of the vector-valued index.

• 대한치과의사협회지
• /
• 제17권12호통권127호
• /
• pp.927-930
• /
• 1979

The use of dentifries in toothbrushing is to aid removal of dental plaque and contribute to good oral hygiene. Therefore, it is important to record the quantity of dental plaque present after toothbrushing. This report concerns with the plaque removal of toothbrushing in a group of dental students who used dentifrices 'X' 'Y' and 'Z' marketed in Korea. And the cleansing effect was examined in accordance with Simplified Oral Hygiene Index. The Following conclusion was obtained. The dentifrices 'X' 'Y' and 'Z' were effective on the removal of dental plaque in the degree of -0.66±0.21, 0.70±0.24 and 0.84±0.19 plaque Index. The differences in the value of plaque Index between the dentifrices 'X', 'Z' and 'Y', 'Z' were significant statistically. The dentifrice 'Z' had the most intensive effects above all.

• 한국환경복원기술학회지
• /
• 제15권2호
• /
• pp.77-84
• /
• 2012

This study suggested the planting model of Zelkova serrata communities in the areas with the warmth index of both 80~100 and $100{\sim}120^{\circ}C{\cdot}month$. Warmth index was calculated with 449 weather points using inverse distance weighted interpolation method. The planting species were selected by correlation analysis between Z. serrata and each species of four or more frequency among the 36 relev$\acute{e}$ surveyed for this study. The result of this study is summarized as follows : Warmth index of Z. serrata communities was among $74{\sim}118^{\circ}C{\cdot}month$. Results of the correlation analysis between Z. serrata and each species observed that the Z. serrata belongs to the tree layer with warmth index of 80~100 and $100{\sim}120^{\circ}C{\cdot}month$. On the other hand, the species of Carpinus laxiflora, Quercus serrata, Prunus sargentii and Platycarya strobilacea appeared only in the tree layer with warmth index of $80{\sim}100^{\circ}C{\cdot}month$. Z. serrata and Styrax japonica appeared in the subtree layer with the warmth index of 80~100 and $100{\sim}120^{\circ}C{\cdot}month$, while Acer pseudosieboldianum, Lindera erythrocarpa, Acer mono, Quercus serrata, etc. appeared in the subtree layer with the warmth index of $80{\sim}100^{\circ}C{\cdot}month$. Z. serrata, Ligustrum obtusifolium, Lindera obtusiloba, Callicarpa japonica and Zanthoxylum schinifolium all appeared in the shrub layer with the warmth index of 80~100 and $100{\sim}120^{\circ}C{\cdot}month$. Lindera erythrocarpa, Orixa japonica, Staphylea bumalda, Akebia quinata and Sorbus alnifolia appeared in the shrub layer with the warmth index of $80{\sim}100^{\circ}C{\cdot}month$ and Styrax japonica and Stephanandra incisa appeared in the shrub layer with the warmth index of $100{\sim}120^{\circ}C{\cdot}month$, The numbers of each species planted in a $100m^2$ area of the Z. serrata community were suggested as follows : five in tree layer, five in subtree layer and nine in shrub layer. The average area of canopy are suggested to be about $86m^2$ for tree layer, $34m^2$ for subtree layer and $34m^2$ for shrub layer.

• 자연과학논문집
• /
• 제7권
• /
• pp.11-17
• /
• 1995

미소 반도체 $Bil_3$ 콜로이드의 광학적 비선형 굴절율을 원형 대칭 빛살을 사용한 Z 스캔 방법으로 측정하였다. 파장 $0.532\mum$, 펄스폭 20ns에서 비선형 굴절율은 주로 열적 요인에 의한 것이었으며, 그 크기는 -1.53 x $10^12($cm^2/W) 이었고, 비선형 흡수율 크기는 7.1 x $10^8$ (cm/W) 이었다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
• /
• pp.225-227
• /
• 2009

본 논문에서는 전압형 3상 ZSI(Z-source Inverter)의 입력전압과 커패시터 충전전압을 검출하고 ZSI의 기본 정의를 이용해 지령전압에 대한 변조지수(Modulation Index)를 결정하는 방법과 출력전압 제어가 가능한 변형된 SVM(공간벡터 변조방식)으로 구성된 알고리즘을 소개한다. 제안된 알고리즘은 ZSI의 이득과 변조지수의 정의를 이용한 간단한 방법으로 변조지수를 변화시켜 출력전압을 일정하게 유지하는 방법이다. PSIM을 통하여 타당성을 입증하였다.

• 대한수학회지
• /
• 제34권2호
• /
• pp.279-284
• /
• 1997

Let L/F be a finite separable extension of Henselian valued fields with same residue fields $\overline{L} = \overline{F}$. Let D be an inertially split division algebra over L, and let $^cD$ be the underlying division algebra of the corestriction $cor_{L/F} (D)$ of D. We show that the index $ind(^cD) of ^cD$ divides $[Z(\overline{D}) : Z(\overline {^cD})] \cdot ind(D), where Z(\overline{D})$ is the center of the residue division ring $\overline{D}$.