• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1515-1522
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• 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.

• Korean Management Science Review
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• v.20 no.2
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• pp.1-16
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• 2003

Previous research on data extraction and integration for data warehousing has concentrated mainly on the relational DBMS or partly on the object-oriented DBMS. Mostly, it describes issues related with the change data (deltas) capture and the incremental update by using the triggering technique of active database systems. But, little attention has been paid to data extraction approaches from other types of source systems like hierarchical DBMS, etc. and from source systems without triggering capability. This paper argues, from the practical point of view, that we need to consider not only the types of information sources and capabilities of ETT tools but also other factors of source systems such as operational characteristics (i.e., whether they support DBMS log, user log or no log, timestamp), and DBMS characteristics (i.e., whether they have the triggering capability or not, etc), in order to find out appropriate data extraction techniques that could be applied to different source systems. Having applied several different data extraction techniques (e.g., DBMS log, user log, triggering, timestamp-based extraction, file comparison) to S bank's source systems (e.g., IMS, DB2, ORACLE, and SAM file), we discovered that data extraction techniques available in a commercial ETT tool do not completely support data extraction from the DBMS log of IMS system. For such IMS systems, a new date extraction technique is proposed which first creates Index database and then updates the data warehouse using the Index database. We illustrates this technique using an example application.

• The Journal of the Acoustical Society of Korea
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• v.20 no.1E
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• pp.31-37
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• 2001

Matched Field Processing (MFP) is a successive process of correcting mismatches between true and assumed parameters by matching the measured acoustic field data with numerically simulated data which we call replica. The MFP is widely used both in geo-acoustic parameter inversions and in source localizations. Whether a certain parameter can be inverted effectively or whether a source can be localized correctly depends on the amount of the influence that a parameter has on the acoustic field during the matching process. Sensitive parameters can be better estimated than the less sensitive ones in MFP. On the contrary, the sensitive parameters affect adversely on the source localization results when they have uncertainties. In this paper, a sensitivity index is defined based upon the field variation resulting from the perturbed parameters. Numerical test results show that the index behaves in accordance with the results of source localization under a mismatched environment and also with the inversion solutions.

• ETRI Journal
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• v.27 no.4
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• pp.377-384
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• 2005

We investigate near-infrared light (NIR) propagation in a model of an adult head using an extensive Monte Carlo (MC) simulation. The adult head model is a four-layered slab which consists of a surface layer, a cerebrospinal fluid layer, a gray-matter layer, and a white-matter layer. We study the effects of a refractive index mismatch on the model, calculating the intensity of detected light, mean flight time, and partial mean flight time of each layer for various refractive indices of the cerebrospinal fluid layer as functions of source-detector spacing. The Monte Carlo simulation shows that the refractive index mismatch presents very rich results including rapidly decaying intensity of detected light and a peak and cross-over in the partial mean flight time with source-detector spacing. We also investigate spatial sensitivity profiles at various source-detector spacings, discussing the index mismatch effect on the model.

• Journal of Distribution Science
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• v.13 no.1
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• pp.57-70
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• 2015

Purpose - Open source software has high utilization in most of the server market. The utilization of open source software is a global trend. Particularly, Internet infrastructure and platform software open source software development has increased rapidly. Since 2003, the Korean government has published open source software promotion policies and a supply promotion policy. The dynamism of the open source software market, the lack of relevant expertise, and the market transformation due to reasons such as changes in the relevant technology occur slowly in relation to adoption. Therefore, this study proposes an assessment model of services provided in an open source software service company. In this study, the service level of open source software companies is classified into an enterprise-level assessment area, the service level assessment area, and service area. The assessment model is developed from an on-site driven evaluation index and proposed evaluation framework; the evaluation procedures and evaluation methods are used to achieve the research objective, involving an impartial evaluation model implemented after pilot testing and validation. Research Design, data, and methodology - This study adopted an iteration development model to accommodate various requirements, and presented and validated the assessment model to address the situation of the open source software service company. Phase 1 - Theoretical background and literature review Phase 2 - Research on an evaluation index based on the open source software service company Phase 3 - Index improvement through expert validation Phase 4 - Finalizing an evaluation model reflecting additional requirements Based on the open source software adoption case study and latest technology trends, we developed an open source software service concept definition and classification of public service activities for open source software service companies. We also presented open source software service company service level measures by developing a service level factor analysis assessment. The Behavior-Structure-Evolution Evaluation Model (BSEM) proposed in this study consisted of a rating methodology for calculating the level that can be granted through the assessment and evaluation of an enterprise-level data model. An open source software service company's service comprises the service area and service domain, while the technology acceptance model comprises the service area, technical domain, technical sub-domain, and open source software name. Finally, the evaluation index comprises the evaluation group, category, and items. Results - Utilization of an open source software service level evaluation model For the development of an open source software service level evaluation model, common service providers need to standardize the quality of the service, so that surveys and expert workshops performed in open source software service companies can establish the evaluation criteria according to their qualitative differences. Conclusion - Based on this evaluation model's systematic evaluation process and monitoring, an open source software service adoption company can acquire reliable information for open source software adoption. Inducing the growth of open source software service companies will facilitate the development of the open source software industry.

• 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.

• Structural Engineering and Mechanics
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• v.12 no.3
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• pp.341-346
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• 2001

Near source earthquakes can be characterized not only by strong horizontal but also by strong vertical ground motions with broad range of dominant frequencies. The inelastic horizontal response of thin-walled L-shaped steel bridge piers, which are popularly used as highway bridge supports, subjected to simultaneous horizontal and vertical ground excitations of near source earthquakes is investigated. A comprehensive damage index and an evolutionary-degrading hysteretic model are applied. Numerical analysis reveals that the strong vertical excitation of a near source earthquake exerts considerable influences on the damage development and horizontal response of thin-walled L-shaped steel bridge piers.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.545-548
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• 2006

This paper presents control method of a Z-source inverter and their relationships of voltage boost versus modulation index. A maximum boost control is presented to produce the maximum voltage boost(or voltage gain)under a given modulation index. The control method, relationships of voltage gain versus modulation index, and voltage stress versus voltage gain are analyzed in detail and verified by experiment.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.6-14
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• 2014

A new method to determine the total harmonic contributions of several customers and the utility at the point of common coupling is presented. The proposed method can quantify the individual harmonic impact of each suspicious harmonic source at the point of common coupling. The individual harmonic impact index is then used to assess the total harmonic contribution of each harmonic source. This index can be calculated by the results processed from instantaneous harmonic voltage and current phasor values. The results demonstrate the performance of the proposed method in terms of steady-state accuracy and response to time-varying operating conditions. The proposed index can be used for billing purposes to control harmonic distortion levels in power systems.

• Speech Sciences
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• v.10 no.3
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• pp.213-224
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• 2003

Spoken sound includes not only speaker's source but the characteristics of vocal tract and speech radiation. This paper is based on the theory of Park[1], who proposes the Phonation Type Index k; a variable that shows the characteristic of speaker's source excluding those of speaker's vocal tract and speech radiation. With Park's theory, we collect data by changing recording environments and expanding experimental data, and analyze the data collected to see whether or not the PTI k shows good discriminating power as a variable for speaker recognition. In the experiment, we repeatedly record 8 sentences ten times for each of 5 males in the environment of a recording room and an office, extract PTI k for each speaker, and measure the discriminating power for each speaker by using the value of PTI k. The result shows that PTI k has the excellent discriminating power of speakers. We also confirm that, even if the recording environment is changed, PTI k shows similar results.