• 천문학회보
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• 제43권2호
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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.

• 소성∙가공
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• 제9권1호
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• pp.59-65
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• 2000

Most studies of failure analysis in ductile metals have been based on the classical plasticity theory using the local constitutive relations. These frequently yields a physically unrealistic solution, in which a numerical prediction of the onset of a deformation localization shows an inherent mesh-size sensitivity. A one way to remedy the spurious mesh sensitivity resulted in the unreasonable results is to incorporate the non-local plasticity into the simulation model, which introduce an internal (material) length-scale parameter into the classical constitutive relations. In this paper, a non-local version of the modified Gurson constitutive relation has been introduced into the finite element formulation of the simulation for plane strain compression of the visco elastic-plastic void material. By introducing the non-local constitutive relations we could successfully removed the inherent mesh-size sensitivity for the prediction of the deformation localization. The effects of non-local constitutive relation are discussed in terms of the load-stroke curve and the strain distributions accross the shear band.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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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++.

• 경영과정보연구
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• 제18권
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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.

• 한국농공학회지
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• 제31권3호
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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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• 제8권2호
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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.

• 대한본초학회지
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• 제21권4호
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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.

• 한국방재학회 논문집
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• 제7권3호
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• pp.19-31
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• 2007

플라이 애쉬와 고로슬래그를 함유하고 물-결합재비가 낮은 고성능 콘크리트의 자기건조에 의한 습도감소와 수축과의 연관성을 파악하기 위하여 내부 습도와 변형률을 측정하였다. 그 결과 일반 콘크리트 내부 습도 감소는 약 10% 수축변형률은 약 $320{\times}10^{-6}$까지 진행하였으며 플라이 애쉬 10%, 20% 혼입한 콘크리트의 경우 각각 10%, 7%의 습도 감소와 $274{\times}10^{-6}$, $231{\times}10^{-6}$의 변형률을 나타내었다. 고로슬래그 40%, 50%를 혼입한 콘크리트는 11%, $371{\times}10^{-6}$, O30G50은 11%, $350{\times}10^{-6}$의 습도감소와 수축 변형률을 나타내었으며 플라이 애쉬 혼입 콘크리트는 일반 콘크리트에 비해 습도 감소량과 변형률이 감소하며 고로슬래그 혼입 콘크리트는 증가하는 경향을 보였다. 자기수축의 경우 내부 습도와 변형률의 관계만을 고려할 때 플라이 애쉬, 고로슬래그 혼입 유무에 상관없이 모두 습도와 변형률은 강한 선형성을 보였다. 콘크리트 내부 습도 변화와 수축변형률의 관계를 보다 구체화하기 위하여 콘크리트 내부 공극을 단일 네트워크로 가정하고 확장 메니스커스 생성 가정 하에 공극수에서 발생하는 모세관 압력과 수화조직체에서 발생하는 표면에너지 변화를 습도의 함수로 모델링하여 수축의 구동력으로 작용시킨 결과 실험값과 비교적 일치하는 값을 나타내었다. 이를 근거로 물-결합재비가 낮은 고성능 콘크리트에서 자기건조에 의한 습도감소는 20nm이하의 소형공극에서 발생함을 파악할 수 있었으며 따라서 자기수축에 대한 제어 방안은 이러한 소형공극에서의 공극수 표면장력과 포화도에 초점을 맞추어야 함을 확인할 수 있었다.

• 한국병원경영학회지
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• 제17권4호
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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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• 제6권1호
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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.