• Journal of Magnetics
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• v.16 no.4
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• pp.391-397
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• 2011

An inductance measurement method for interior permanent magnet synchronous machine (IPMSM) is proposed in this paper. In this method, the motor is measured at standstill condition, and only a 3-phase voltage source, an oscilloscope and a DC voltage source are required. Depending on the deductive dq-axis voltage equations in the stationary frame of reference, the dq-axis inductances at different current magnitude and vector angle can be calculated by the measured 3-phase voltages and currents. And hence, the saturation and cross-magnetizing effect of the inductances are measurable. This paper introduces the principle equations, experiment setup, data processing, and results comparison on the concentrated-winding and distributed-winding IPMSMs.

• Journal of Korean Library and Information Science Society
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• v.23
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• pp.253-284
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• 1995

The purpose of this paper is to analyse the current status of reference education and to suggest directions for reference education in America and in Korea. For this purpose, the historical developments of reference services, and the names, problems and changes of reference courses are studied. The findings of the study can be summarized as follows; 1. The names of reference courses are various. In America, On-Line Services or Information Services are used in general, but in Korea, Reference Services are widely used. 2. In America, some library schools have only subject literature courses including business, law, music, etc. instead of basic reference courses. 3. Only one reference course is given by most schools in America and in Korea. However, a few schools which have no graduate courses provide two reference courses in Korea. 4. Analysis of textbooks used in reference courses shows that Reference Research by Joon-Shik Park, Reference Services and Reference Sources by Ock-Soon Noh are used in general. In addition, Introduction to Reference Work by Katz is used. 5. Lecture methods are generally used in teaching reference courses, but reviews of reference materials in library, class presentation, and case study method are also used. It is desirable that role playing and pathfinders' used in U.S. are introduced to our schools. 6. Analysis of library user instruction courses in Korea shows that 7 of 11 universities have the courses,, only one university teaches library user instruction as a part of reference courses, 3 universities don't. 7. Analysis of opinions about the directions for reference education shows that changes of reference courses names, expansion of courses contents, emphasis on communication technique, changes of teaching methods, proper combination of theory vs. practice, an increase in electronic reference education and training of subject specialist are needed.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.106-111
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• 2015

Since most reference voltage generator circuits have bi-stable characteristics, it is important to employ a proper start-up circuit to operate a reference generator in the desired state. In this paper, we propose a start-up circuit for a low voltage reference generator. This start-up circuit determines the state of the circuit reliably by measuring the current drawn by BJTs in the circuit, which is well-defined in the desired state. To measure the current using CMOS-compatible devices only, a comparator with an internal offset voltage is used. The reliability of the proposed circuit is confirmed by Monte-Carlo simulations of the start-up operation, which show that, with the proposed start-up circuit, the low voltage reference generator starts reliably with supply voltages over 850mV even in the presence of device mismatches.

• Journal of the Korean Society for Library and Information Science
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• v.33 no.4
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• pp.65-83
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• 1999

This study is intended to build a cross-reference system as syndetic device to provide bibliographic relations and to collocate variant access points through references, by developing a reference record format. To this end, the method of this study are as follows: First, the roles of references, which have long been used in traditional records, have been reviewed. Second, ways in which references are depicted not only by current cataloging rules but also by authority control systems are examined. Major characteristics of the reference record are summarized as fellows: 1) If variations either of an author name or of a title are made, or any related works are published, only a single reference record is created. This record uses existing authority records, and instead of adopting authority headings, it will expand the function of the explanatory reference as well as newly implementing a relational reference which can later be used as a reference record. 2) All the variations of identical personal or group names and of lilies are dealt as one access point. In place of current 'see' and 'see also' references, not drawing lines between authority heading(1XX field), 'see'(4XX field) and 'see also' reference(5XX field), all forms of names will be simply applied to record field '1XX'. 3) Any form of data elements, which are used as access points, will be described in '1XX' which has equal value. When a need arises to explain relationships between various access points, it can be met by applying the general explanation reference-name(666 field). Similarly, when there is a need to articulate bibliographic relationships between related works, they will be suggested through the title and relational reference. 4) The title and relational reference regulates related terms that each relation type contains its field, according to each relational type, by reclassifying entire fields in order to provide direct bibliographic relation types on reference records. 5) Pointers which are connected to each access point present reference control numbers.

• Transactions on Electrical and Electronic Materials
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• v.17 no.5
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• pp.289-292
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• 2016

This paper dealt with the optimal design of a follow current disconnector for DC arresters used in electric traction vehicles. The disconnector separates the ground lead from an arrester to prevent a line-to-ground fault of an aged arrester and should not affect the operation and function such as the reference and the clamping voltage of the connected arrester. The designed disconnector is composed of a resistor, a spark gap, and a cartridge. The results showed that the sparkover voltage increased with the gap distance whereas the reference voltage was almost the same as that without the disconnector. The sparkover voltage was 3.95 kV when the gap distance was 0.5 mm. Regardless of the gap distance, the reference and the clamping voltage of the assembled disconnector with an arrester were measured to be the same as those of the arrester alone.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.145-147
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• 2005

In present, most of metallic structures(gas pipeline, oil pipeline, water pipeline, etc) are running parallel with subway and power line in seoul. Moreover subway system and power line make a stray current due to electrical corrosion on metallic structures. The owner of metallic structures has a burden of responsibility for the protection of corrosion and the prevention against big accident such as gas explosion or soil pollution and so on. So, they have to measure and analyze the data about P/S(Pipe to Soil) potential due to stray current of subway system. So, we have developed the Real-time Wireless Remote Monitoring System for Stray Current of Subway System. In this system, the permanent buried type reference electrode is necessary. In this paper, results of development of buried type reference electrode using porous ceramic$({\alpha}-Al_{2}O_{3})$ are presented.

• Journal of Power Electronics
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• v.13 no.1
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• pp.122-138
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• 2013

Adaptive control of a peak current mode controlled (PCM) boost converter supplied by a PEM fuel cell is described in this paper. The adaptive controller with reference model and signal adaptation is developed in order to compensate the deviation of the response during the change of the operating point. The procedure for determining the adaptive algorithm's weighting coefficients, based on a combination of the pole-zero placement method and an optimization method is proposed. After applying the proposed procedure, the optimal adaptive algorithm's weighting coefficients can be determined in just a few iterations, without the use of a computer, thus greatly facilitating the application of the algorithm in real systems. Simulation and experimental results show that the dynamic behavior of a highly nonlinear control system with a fuel cell and a PCM boost converter, can fairly accurately be described by the dynamic behavior of the reference model, i.e., a linear system with constant parameters.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1480-1482
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• 2005

The major causes of power quality deterioration are harmonic current through semiconductor switching device, due to use of nonlinear loads such as diodes rectifier or thyristor rectifiers. In response to this concerns, this paper presents a new control method of single-phase active power filter(APF) for the compensation of harmonic current components in nonlinear loads. In order to make the complex calculation to be possible, the single-phase system that has two phases was made by constructing a imaginary second-phase giving time delay to load currents. In the conventional method, a imaginary-phase lagged to the load current T/4(here T is the fundamental cycle) was made. But in this proposed method, the new signal, which has the delayed phase through the filter, using the phase-delay property of low-pass filter, was used as the second phase. As this control method is applied to the system of single phase, an instantaneous calculation was done rather by using the rotating reference frames that synchronizes with source-frequency than by applying instantaneous reactive power theory that uses the conventional fixed reference frames.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.5
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• pp.367-375
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• 2022

Generally, a proportional-resonant controller is used to eliminate steady-state errors during the voltage-current control of a double-conversion uninterruptible power supply (UPS) in a stationary reference frame. Additionally, the feed-forward control compensating for the load current, which can be considered a disturbance of the voltage controller, can be used to improve the disturbance rejection performance. However, during the parallel operation of UPSs, circulating current can occur between UPS modules when performing both feed-forward control and droop control because feed-forward control reduces the circulating current impedance. This study proposes a feed-forward compensation technique that considers the impedance of circulating current. An additional feed-forward compensation technique is developed to enhance the disturbance rejection performance. The validity of the proposed feed-forward compensation technique is verified by the experiment results of the parallel operation of a 500 W double-conversion UPS module.

• The Transactions of the Korean Institute of Power Electronics
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• v.28 no.1
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• pp.30-38
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• 2023

In this paper, a constant current(CC) and constant voltage(CV) control method using a primary-side regulated(PSR) fly-buck converter is proposed. Because the primary-side structure of the fly-buck converter is the same as that of the synchronous buck converter, it always operates in continuous conduction mode(CCM). Therefore, in the proposed method, the load information on the secondary side can always be easily estimated by measuring the primary inductor current at the midpoint of the switch-on period. An accurate CC/CV control can be achieved through simple calculations based on this estimated information. Consequently, the proposed method is advantageous for optimizing the control performance of the PSR converter. The validity of the proposed control was verified using a 5 W prototype of a PSR fly-buck converter. The experimental results confirmed that the current reference of 500 mA was followed within the error range of 1.2%, and that the voltage reference of 12 V was followed within the error range of 1.8% despite the indirect control of the load current and output voltage from the primary side.