• Progress in Superconductivity
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• 제11권1호
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• pp.19-24
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• 2009

Among the various types of fault current limiters, superconducting fault current limiters could be the most preferable choice for high voltage electric power systems owing to the remarkable current limiting characteristics of superconductors. But, there have been no commercial superconducting fault current limiters which were installed into actual electric power systems until these days due to some remained technical and economical problems. Thus, in order to promote the development and application of the superconducting fault current limiters into real field, it is essential to understand the power utilities’ requirements for their networks and also suitable test method and some specifications should be prepared. This paper focuses on the matters of test requirements and standardization issues that should be prepared for commercialization of superconducting fault current limiters. The unique current limiting characteristics of superconducting fault current limiters were investigated and related other standards including circuit breakers, transformers, reactors, power fuse, and fused circuit breakers were compared to setup the basis of novel specification of superconducting fault current limiters. Furthermore, required essential test procedures for superconducting fault current limiters were suggested.

• Journal of electromagnetic engineering and science
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• 제16권4호
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• pp.225-228
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• 2016

KRISS-V, a V-band millimeter-wave source module for a primary RF power standard and calibration system developed by the Korea Research Institute of Standards and Science is here presented. The output power of KRISS-V is several times higher than that of commercial amplifier/multiplier chains and is highly stable (the standard deviations of output power are less than 0.01% in the worst case). The spectral purity of KRISS-V is high enough to consider it a single-tone signal generator. We also added programmable attenuation capability to KRISS-V for remote power control. Moreover, the in-house source module is cost-effective and adaptable to various measurement schemes. The structure of the model as well as detailed component information are introduced so that it can be reproduced.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.45-46
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• 2017

The operating characteristics of power MOSFETs greatly vary depending on the junction temperature. A PSpice thermal model is implemented to simulate the temperature characteristics of the power MOSFETs in this paper. A thermal model is derived that can be applied online in PSpice simulations and PSpice parameters are reconstructed using a curve fitting from commercial data sheets. The implemented PSpice model is applied to the buck converter and the validity of the model is verified through experiments.

• Communications for Statistical Applications and Methods
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• 제8권2호
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• pp.453-464
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• 2001

A commercial nuclear power station contains at least tow emergency diesel generators(EDG) to control the risk of severe core damage during station blackout accidents. Therefore, the reliability of the EDG's to start and load-run on demand must be maintained at a sufficiently high level. Probabilistic safety assessments(PSA) are increasingly being used to quantify the public risk of operating potentially hazardous systems such as nuclear power reactors. In this paper, to perform PSA, we will introduce three different types of data and use Bayes procedure to estimate the error rate of nuclear power plant EDG, and using practical examples, illustrate which method is more reasonable in our situation.

• Communications for Statistical Applications and Methods
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• 제13권3호
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• pp.685-699
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• 2006

Commercial banks and other related areas have developed internal models to better quantify their financial risks. Since an appropriate credit risk model plays a very important role in the risk management at financial institutions, it needs more accurate model which forecasts the credit losses, and statistical inference on that model is required. In this paper, we propose a new method for estimating a default rate. It is a Bayesian approach using the power prior which allows for incorporating of historical data to estimate the default rate. Inference on current data could be more reliable if there exist similar data based on previous studies. Ibrahim and Chen (2000) utilize these data to characterize the power prior. It allows for incorporating of historical data to estimate the parameters in the models. We demonstrate our methodologies with a real data set regarding SOHO data and also perform a simulation study.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.771-774
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• 2007

Integrated Gasification Combined Cycle (IGCC) power plant converts coal to syngas, which is mainly composed with hydrogen and carbon monoxide, by the gasification process and produces electric power by the gas and steam turbine combined cycle power plant. The purpose of this study is to investigate the influence of the syngas to the performance of a gas turbine in a combined cycle power plant. For this purpose, a commercial gas turbine is selected and its performance characteristics are analyzed with syngas. It is found that different heating values of those fuels and chemical compositions in their combustion gases are the causes in the different performance characteristics. Also, Changing of turbine inlet Mass flow lead to change the turbine matching point, in the event the pressure ratio is changed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.696-699
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• 2004

This paper proposes the Low Cost Class-E Converter with Power Conversion Operation of Piezoelectric Transformer. The Power Piezoelectric transformer capacity used in the proposed circuit is 15W and the electric equivalent circuit is presented. Class E type converter has some merits such as small component count, small size, and low cost. The topology has also ZVS conditions for main switch, thus in efficiency aspect, it is also competitive for commercial feasibility. The analysis and design guideline are suggested and also they are verified by experimental results.

• 대한조선학회지
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• 제3권1호
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• pp.25-32
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• 1966

For preliminary estimation of ships' machinery weights, many papers giving well-judged data and discussions for rational method of estimation, such as [1], [2], [3], [4], [5], [6], are available, however, they are mostly concerned with large ships propelled by power more than about 2, 000 horsepower. Regarding the medium and small-sized ships, as far as the author is aware, fragmental data and vague discussions found in various technical literature are the all available. In this paper, available data concerned with machinery weights of commercial ships propelled by direct-drive diesel plants of power below 3, 000 horsepower with single screw propeller are collected and analysed to obtain systematic data Fig. 1 and Fig. 2 as weight to power ratio versus power per shaft diagrams together with suplementary data Fig. 1 and Fig. 3. Influences of various factor such as revolutions per minute, mean effective pressure, type and construction of the main units on machinery weights are also investigated in detail to give a better guidance for logical and rational utlization of the proposed diagrams in preliminary estimation of machinery weights.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1481-1483
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• 1999

Power distribution system planning for maximum customer satisfaction and system efficiency requires accurate forecast of future demand in service area. Spatial load forecasting method provides a more accurate estimation of both magnitudes and location of future electrical load. This method considers the causes of load growth due to addition of customers and per capita consumption among customers by land use (residential, commercial and industrial). So the land-use study and it's preference for small area is quite important. This paper proposes land-use preference estimation method based on fuzzy logic. Fuzzy logic is applied to computing preference scores for each land-use and by these scores the customer growth is allocated in service area. An simulation example is used to illustrate the proposed method.

• 한국정밀공학회지
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• 제28권2호
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• pp.211-218
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• 2011

We reported the design, prototype, test drive, and mechanical & electrical engineering analyses of a power-lifting wheelchair using mecanum wheels. Mecanum wheels enable translational and rotational movement of the device in any direction on the ground. The power-lifting capability enables the seated individual to reach the standing height of a non-disabled individual. This mecanum wheelchair is fully controlled by the joystick attached to the armrest. The motion of the wheelchair and lifting action of the seat were studied using statics and dynamics. We believe this mecanum wheelchair is a prime candidate for commercial production.