• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.842-848
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• 2020

Purpose: It is important to operate safely and economically in obsolescent power plant facilities. Economical operation is related in the balance of the supply and demand. Safety operation predicts the possible risks in the facilities and then, takes measures to the facilities. For the monitoring of the power plant facilities, we needs several kinds of the sensing system. From the sensors data, we can predict the possible risk. Method: We installed the acoustic, vibration, electric and smoke sensors in the power plant facilities. Using the data, we developed 3 kinds of prediction models, such as, demand prediction, plant engine abnormal prediction model, and risk prediction model. Results: Accuracy of the demand prediction model is over 90%. The other models make a stable operation of the system. Conclusion: For the sustainable operation of the obsolescent power plant, we developed 3 kinds of AI prediction models. The model apply to JB company's power plant facilities.

• The Korean Journal of Ceramics
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• v.1 no.1
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• pp.45-54
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• 1995

Four kinds of silicon nitride based ceramic materials have been hot pressed. Effect of the sintering additives on the phase transformation, microstructural development and mechanical properties was investigated. While sintering under the same condition a big difference among the microstructures of the specimens, they appeared alike if sintered to have a similiar $\alpha$-$\beta$ phase ratio. The specimen of the stoichiometric $\alpha$-$\beta$ sialon composition showed very limited amount of the intergranular glassy phase and a significant degree of the residual stress. It exhibited almost no strength degradation up to $1300^{\circ}C$, and the strength of the specimen degraded more as its composition deviated from the stoichiometry.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.5
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• pp.779-788
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• 2003

This study evaluates the approximation errors of the existing linearized equation for a servovalve nonlinear flowrate characteristic. At first, the errors are evaluated on flowrate/pressure characteristics diagrams. Subsequently, they are investigated with time response simulation results for several hydraulic control systems. To enable systematic evaluation of computational error, the authors propose three kinds of equations with restructured forms of the existing linearized equation. As results of the evaluations, it is ascertained that comparatively good computational accuracy can be achieved with the existing linearized equation when both an operating point for the linearized equation and operating range of the hydraulic system stay near the flowrate axis of the flowrate/pressure characteristics diagram. In addition, the results show that comparatively big computational error may occur when operating range of a hydraulic system stay apart from the flowrate axis of the flowrate/pressure characteristics diagram.

• Textile Coloration and Finishing
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• v.11 no.6
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• pp.43-50
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• 1999

Lichen had been used as dyestuffs before the discovery of synthetic dyes in Europe and by American Indians. To investigate the dyeability of Korean native lichens, 10 kinds of lichen were collected and colorants were extracted from them by boiling in water and fermenting in ammonia water. Silk fabrics were dyed with lichen extract, then the colour differences of dyed silk fabrics were measured before and after color fastness test. The most part of the lichen extracts(Fc, Hh, Me, Pl, Xm, Pr, Cj, Ld, Ry) dyed silk yellowish or reddish brown. The range of colors were 2.4Y 6.5∼10YR 6/7. Pa extract dyed silk purple(1.25RP 5/6). Color differences of laundered specimen with the silk before laundering were very small, but color of the dyed silks after exposing to light showed big differences with the specimen before exposing to light. The colors of the silks dyed with lichens changed from yellowish or reddish brown to greenish brown by laundering and by exposing to light. But the specimen dyed Pa extract changed from purple to blueish purple by laundering and reddish purple by exposing to light.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.4
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• pp.284-288
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• 1993

Tow Kinds of Soils, vertisol and alfisol, were selected and analyzed pore space distribution(PSD) by mercury intrusion method and soil water potential after freeze-drying from different water conditions, such as 0.033MPa, 1.5MPa and ovendry. The PSD values measured by mercury intrusion method were higher in large pores than the values from soil water potential. Also, there were big differences of PSD by the changes of the water content befor freeze-drying.

• Journal of electromagnetic engineering and science
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• v.5 no.4
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• pp.172-175
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• 2005

Sometimes, it is more convenient to use paint-type and spray-type EM wave absorbers than bulk-type or sheet-type. Thus, in this paper, we prepared paint-type and spry-type EM wave absorbers. The proportion of ferrites to paints, particle size of magnetic material, and kinds of paint should be considered to prepare a superior paint-type EM wave absorber. There is no big gap between spray-type and paint-type in EM wave absorption of EM wave absorbers prepared with same composition.

• Korean Journal of Mathematics
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• v.22 no.3
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• pp.529-552
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• 2014

As we know, some indices and data are strong influence to the price movement of some assets now, but not to another assets and in future. Thus we define some asset models for several time intervals; intraday, weekly, monthly, and yearly asset models. We define these asset models by using Brownian motion with volatility and Poisson process, and several deterministic functions(index function, twitter data function and big-jump simple function etc). In our asset models, these deterministic functions are the positive or negative levels of auxiliary indices, of analyzed data, and for imminent and extreme state(for example, financial shock or the highest popularity in the market). These functions determined by indices, twitter data and shocking news are a kind of one of speciality of our asset models. For reasonableness of our asset models, we introduce several real data, figurers and tables, and simulations. Perhaps from our asset models, for short-term or long-term investment, we can classify and reference many kinds of usual auxiliary indices, information and data.

• International Journal of Contents
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• v.7 no.1
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• pp.23-28
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• 2011

In a SoC (system-on-chip) design, a design complexity is a big bottleneck. In order to overcome the design complexity, platform based design method is widely adopted for designers. Most complex SoCs need a heterogeneous design development environment for hardware and software co-design. In this paper, we discuss about some kinds of verification approaches with platform based design methodology at various abstraction levels of SoC design. We separate the verification process to two steps according to the different levels of verification. We employ a flexible SoC design environment to support simultaneous hardware and software development. We demonstrate the verification strategy of a target SoC design, IEEE 802.11a WLAN SoC.

• Communications of the Korean Mathematical Society
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• v.35 no.2
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• pp.447-454
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• 2020

The studies of reversible and NI rings have done important roles in noncommutative ring theory. A ring R shall be called QRUR if ab = 0 for a, b ∈ R implies that ba is contained in the upper nilradical of R, which is a generalization of the NI ring property. In this article we investigate the structure of QRUR rings and examine the QRUR property of several kinds of ring extensions including matrix rings and polynomial rings. We also show that if there exists a weakly semicommutative ring but not QRUR, then Köthe's conjecture does not hold.

• Plant Resources
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• v.4 no.3
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• pp.157-160
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• 2001

The wild Pyrus plants belong to the deciduous woody plants in Rosaceae family. Most are cultivated for fruit productions, but some for ornamental plants. There are 5 Pyrus species including Pyrus ussuriensis and 8 varieties cultivated in Korea. In Korea, these plants are populated near villages or on the hills, and they are easily propagated since their fruit are very juicy and quite big in size. Plant breeding to get improved cultivars is not difficult because the Pyrus plants are easy to cross breeding among its genus. Because not only this reason but there have been shown lots of variation in wild groups, the Pyrus plants inhabited in Korea are excellent deciduous woody plants and favorable fruit trees to develop ornamental plants. It is necessary to develop many kinds of fruit trees and ornamental trees containing genetically different character, so that it will be satisfied for many different people's taste and demands. Collecting lots of wild plant resource with diverse genes is necessary for plant breeding.