• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.6-11
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• 2009

In this study, the internal waves in two-density layered fluids were analyzed using the Numerical Wave Tank (NWT) technique in the frequency domain. The NWT is based on a two-domain Boundary Element Method with the potential fluids using the whole-domain matrix scheme. From the mathematical solution of the two-domain boundary integral equation, two different wave modes could be classified: a surface wave mode and an internal wave mode, and each mode were shown to have a wave number determined by a respective dispersion relation. The magnitudes of the internal waves against surface waves were investigated for various fluid densities and water depths. The calculated results are compared with available theoretical data.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.47.2-47.2
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• 2018

The umbral oscillations of velocity are commonly observed in the chromosphere of a sunspot. Their sources are considered to be either the external p-mode driving or the internal excitation by magnetoconvection. Even though the possibility of the p-mode driving has been often considered, the internal excitation has been rarely investigated. We report the observational evidence for the internal excitation obtained by analyzing velocity oscillations in the temperature minimum region of a sunspot umbra. The velocity oscillations in the temperature minimum region were determined from Fe I $5435{\AA}$ line data taken by the Fast Imaging Solar Spectrograph (FISS) of the 1.6 m Goode solar Telescope (GST) at the Big Bear Solar Observatory. As a result, we discovered 4 events of oscillations which appear to be internally excited. We analyze their characteristics and relation to photospheric features. Based on these results, we estimate the contribution of the internal excitation for umbral oscillations and discuss their importance.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.439-444
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• 1999

This paper presents an authoring system for users to create and edit multimedia documents more easily. Our system supports dynamic authoring to feedback the inconsistency that could be occurred when users authorize and flexible media synchronization. For these, we define a new time relation based on causal relation and provide an internal representation using trees and structured document parsing. The system consists of the components such as visual interface, parsing, and presentation engine. It has been implemented on Microsoft Windows 95 with Visual C++.

• Management & Information Systems Review
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• v.18
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• pp.69-90
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• 2006

In this empirical study, we try to find major factors influencing the selection of technology acquisition strategy, and to examine the relation between technology acquisition strategies and corporate performances. The results of this study are as follows. Firstly, it is required to make intrinsic efforts for the harmony of technology acquisition strategies, which guarantees the effective acquirement of new technology. Secondly, we should pay particular attention to the harmony of external and internal resources for the corporate growth, Finally, the development of new technology is to be made on the basis of technology acquisition strategy established in terms of resources.

• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.3
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• pp.57-69
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• 1989

The study was carried out for the strength parameter of coarse grained Soil and slope stability analysis of earth dam. The test samples were taken fifteen kinds of soil from cohesive soil to coarse gravel. The degree of compaction of test samples for shear test and permeability test was chosen 95 percentage of maximum dry density. The results of this study are as follows ; 1.The maximum dry density(Yd) of coarse grained soil increase in proportion to coarse particles(P) with the relation of Y d= 1.609+0.0043P. 2.The coefficients of permeability(k) decrease by the increase of fine particles(n) with the relation of k=0.0426e-0 185n. 3.The cohesions of soil decrease by the increase of coarse particles, but internal friction angles are more increased in same condition. 4.The internal friction angles(${\Phi}$) decrease in inverse proportion to void ratio(e) with the relation of ${\Phi}$ = 73.068 - 69.268e. 5.The strength parameters( Ct ${\Phi}$t) by triaxial compression test are clearly smaller than that (Cd, ${\Phi}$d) by direct shear test in fine grained soil, but the differences between both parameters are a little in coarse grained soil.The relations of both parameters are as follows; Ct = O.544Cd + 0.04 ${\Phi}$t= 1.282${\Phi}$d-2306 6.In cohesive soil, the strength parameters( Cl ${\Phi}$l) by large size shear test apparatus are similar to the strength parameters(Cs , ${\Phi}$s) by small size shear test appratus, but Cs and ${\Phi}$s values are larger than Cl and ${\Phi}$l values from 10 percentage to 20 percentage in coarse grained soil. 7.The fine grained soil is inappropriate to high dam more than 20 meters and it must be taken coarse grained soil with high internal friction angle for high dam.

• International Journal of Automotive Technology
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• v.8 no.2
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• pp.137-147
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• 2007

Homogenous Charge Compression Ignition (HCCI) combustion systems can be broadly divided for the process applied to 4-stroke and 2-stroke engines. The former process is often referred to as simply HCCI combustion and the latter process as Active Thermo-Atmosphere Combustion (ATAC). The region of stable engine operation tends to differ greatly between the two processes. In this study, it was shown that the HCCI combustion process of a 4-stroke engine, characterized by the occurrence of autoignition under a high compression ratio, a lean mixture and wide open throttle operation, could be simulated by operating a 2-stroke engine at a higher compression ratio. On that basis, a comparison was made of the combustion characteristics of high-compression-ratio HCCI combustion and ATAC, characterized as autoignited combustion in the presence of a large quantity of residual gas at a low compression ratio and part throttle. The results showed that one major difference between these two combustion processes was their different degrees of susceptibility to the occurrence of cool flame reactions. Compared with high-compression-ratio HCCI combustion, the ignition timing of ATAC tended not to change in relation to different fuel octane numbers. Furthermore, when internal EGR was applied to high-compression-ratio HCCI combustion, it resulted in combustion characteristics resembling ATAC. Specifically, as the internal EGR rate was increased, the ignition timing showed less change in relation to changes in the octane number and the region of stable engine operation also approached that of ATAC.

• The Korea Journal of Herbology
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• v.21 no.4
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• pp.213-218
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• 2006

Objectives : Radix Bupleuri is from the dried root of the herb of the Perennial herbaceous plant, Bulpleurum falcatum L. or Bulpleurum chinense DC. or Bulpleurum. scorzonerifolium Willd., family Umbelliferae. Medicinal Properties are bitter and pungent in flavor, slightly cold in nature and attributed to the liver and gallbladder meridians. Actions in modern Materia Medica are regulate the functional relation of internal organs to relieve fever, disperse the stagnated liver-qi and uplift yang-qi to raise sinking. The ‘uplift yang-qi to raise sinking’ efficacy, out of three efficacies (regulate the functional relation of internal organs to relieve fever, disperse the stagnated liver-qi and uplift yang-qi to raise sinking), has been disputed in the medical profession for a long period. Hereupon, this study ascertained the reason why it has been disputed. Methods : With respect to this medicinal herb, the efficacies of regulate the functional relation of internal organs to relieve fever, disperse the stagnated liver-qi and uplift yang-qi to raise sinking were described as to what was written in ‘Shen Nong's Herbal’ from Chin and Han dynasties until Jin and Yuan dynasties. Results : The beginning of Jin and Yuan dynasties, it began to deal with the ‘uplift yang-qi to raise sinking’ efficacy and so it has been carried on modern textbooks and medical books. The reason why it was added is that it was influenced by the theory of ‘Raise Sinking’ advocated by Zhang jieku who lived in the period of Jin and Yuan dynasties. Since then, the properties of ‘Radix Bupleuri’ have been wrongly known to the public. Additionally, ‘Radix Stellariae Seu Gypsophilae’, which was begun to be introduced from the Four Cities since the Five Dynasties, has been combined with the best stuffs of ‘Radix Bupleuri’ produced from Yin Zhou. Consequently, its original properties were remarkably disordered. Likewise, respective medical schools’ theories were changed by the influence of ‘Bulpleurum. scorzonerifolium Willd’ begun to be used since Tang dynasty. Conclusion : it is considered that the current ‘Raise Sinking’ efficacy of Radix Bupleuri is unreasonable to be applied to the efficacy of the whole Radix Bupleuri because it is limited to certain species.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.3
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• pp.19-31
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• 2007

Humidity and strain were estimated for understanding the relation between humidity change by self-desiccation and shrinkage in high-performance concrete with low water binder ratio and containing fly ash and blast furnace slag. Internal humidity change and shrinkage strain were about 10%, 10%, 7%, 11%, 11% and $320{\times}10^{-6}$, $270{\times}10^{-6}$, $231{\times}10^{-6}$, $371{\times}10^{-6}$, $350{\times}10^{-6}$ respectively on OPC30, O30F10, O30F20, O30G40, O30G50 and from the results, fly ash made humidity change and strain decrease but slag increase comparing with ordinary portland cement. Considering only relation internal humidity and shrinkage by self-desiccation, humidity change and shrinkage represented the strong linear relation regardless of mineral admixture. For specifying the relation on internal humidity change and autogenous shrinkage strain, shrinkage model was established which is driven by capillary pressure in pore water and surface energy in hydrates on the assumption of a single network and extended meniscus in pore system of concrete. This model and experimental results had a similar tendency so it would be concluded that the internal humidity change by self-desiccation in HPC originated in small pores less than 20nm, therefore controlling plan on autogenous shrinkage might be focused on surface tension of water and degree of saturation in small pore.

• Korea Journal of Hospital Management
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• v.17 no.4
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• pp.87-115
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• 2012

This research classified hospital specialization strategy types through cluster analysis, analyzed fitness of hospital specialization strategy types for external environment or organizational structure, and examined relation between hospital specialization strategy types and organizational performance. This research surveyed 1,437 hospitals which have more than 30 patient's bed and practice national health service in Korea. Specifically, this research divided into two part : external fit - analysis of relation between external environment and specialization strategy, internal fit-analysis of relation between organizational structure factors and specialization strategy. also, as the organizational performance for achieving specialization strategic purpose, not only the productivity, efficiency, profit but also the medical quality was considered. In case of external fit, many hospitals chose integration type if there are a lot of competitive hospitals and regional population. Particularly, if there are many competitive hospitals, concentration type is chosen. In contrast, if there are many doctors in the region, differentiation type is chosen. In case of internal fit, according to organization type and patient's bed number, hospitals chose different types. If it is a general hospital and has a few bed number, generalization or concentration type is chosen. Tertiary hospital or the hospital with many patient's bed chose differentiation type. According to the number of specialists, if there are a few specialists, generalization or concentration type is chosen. If there are many specialists, differentiation type has high fitness for the hospital. In relation to strategy types and organizational performance, differentiation type has best result. Differentiation type has a good result in 7 items out of 11.

• Ocean Systems Engineering
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• v.6 no.1
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• pp.117-128
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• 2016

A theoretical study of Boussinesq equations (BEs) for internal waves propagating in a two-fluid system is presented in this paper. The two-fluid system is assumed to be bounded by two rigid plates. A set of three equations is firstly derived which has three main unknowns, the interfacial displacement and two velocity potentials at arbitrary elevations for upper and lower fluids, respectively. The determination of the optimal BEs requires a solution of depth parameters which can be uniquely solved by applying the $Pad{\acute{e}}$ approximation to dispersion relation. Some wave properties predicted by the optimal BEs are examined. The optimal model not only increases the applicable range of traditional BEs but also provides a novel aspect of internal wave studies.