• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.34.2-34.2
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• 2019

Several observational results show a tighter pitch angle at wavelengths of optical and near-infrared than those that are associated with star formation, which is in agreement with the prediction of the density wave theory. In my recent numerical studies, the dependence of the shock positions relative to the potential minima is due to the tendency that stronger shocks form farther downstream. This causes a systematic variation of the perpendicular Mach number, with radius and makes the pitch angle of the gaseous arms smaller than that of the stellar arms, which supports the prediction of the density-wave theory, independently. However, some observations still give controversial results which show similar pitch angles at wavelengths, and there is no statistical study comparing observations and numerical models directly. By analyzing optical image of disk galaxies in the Carnegie-Irvine Galaxy Survey (CGS), I measured the physical values of stellar and gaseous arms such as their strength, length, and pitch angles. For direct comparison with numerical results, I analyzed more than 30 additional numerical models with varying the initial parameters in model galaxies. In this talk, I will present results both of observational and numerical samples and discuss the physical properties of spiral structures based on the density-wave theory.

• Geomechanics and Engineering
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• v.24 no.3
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• pp.295-305
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• 2021

In this study, design charts for estimating consolidation settlement are proposed according to finite strain consolidation theory using a nonlinear constitutive relationship equation. Results of parametric sensitivity analysis shows that the final settlement, initial height, and initial void ratio exerted the greatest effect, and the coefficients of the void ratio-effective-stress. Proposed design charts were analyzed for three regions using a representative constitutive relationship equation that enables major dredged-reclaimed construction sites in Korea. The regional design charts can be calculated accurately for the final settlement because it is applied directly to the numerical analysis results, except for reading errors. A general design chart applicable to all marine clays is proposed through correlation analysis of the main parameters. A final self-weight consolidation settlement with various initial void ratios and initial height conditions should be estimated easily using the general design chart and constitutive relationship. The estimated final settlement using the general design chart is similar to the results of numerical analysis obtained using finite strain consolidation theory. Under an overburden pressure condition, design charts for estimating consolidation settlement are proposed for three regions in Korea.

• Advances in nano research
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• v.12 no.2
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• pp.139-150
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• 2022

This paper presents sets of explicit analytical equations that compute the static displacements of nanobeams by adopting the nonlocal elasticity theory of Eringen within the framework of Euler Bernoulli and Timoshenko beam theories. Castigliano's theorem is applied to an equivalent Virtual Local Beam (VLB) made up of linear elastic material to compute the displacements. The first derivative of the complementary energy of the VLB with respect to a virtual point load provides displacements. The displacements of the VLB are assumed equal to those of the nonlocal beam if nonlocal effects are superposed as additional stress resultants on the VLB. The illustrative equations of displacements are relevant to a few types of loadings combined with a few common boundary conditions. Several equations of displacements, thus derived, matched precisely in similar cases with the equations obtained by other analytical methods found in the literature. Furthermore, magnitudes of maximum displacements are also in excellent agreement with those computed by other numerical methods. These validated the superposition of nonlocal effects on the VLB and the accuracy of the derived equations.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.45-51
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• 2008

This paper presents theoretical and experimental analysis on the characteristics of the power spectrum of electormagnetic waves radiating from the spark plug and their cables of a distributorless ignition system. The theoretical study was conducted applying the microwave transmission line theory and the antenna theory. The experimental works were carried out to measure the standing wave ratio(SWR) and the radiation power spectrum of this system. As a result, it has been found that a spark plug and its cable is working as a monopole antenna radiating elelctromagnetic waves. Because of its similar structure to a monopole antenna, the envelope of radiation power spectrum distribution has a bell shape which can be obtained from a monopole antenna operating as a series resonant circuit. The frequency characteristics from the SWR measurements show a similar frequency characteristics of power spectrum of the system studied. Also, it has been found that the density of the power spectrum of the system fitting a long time used spark plug is higher than that of fitting a new spark plug.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2212-2218
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• 2015

In order to find out the load bearing behavior of sand and clay which sustain three types of shallow footing, finite element analyses were performed. Failure zone of sand which sustain strip footing was affected by relative density of sand whereas, failure zone of clay was not affected by soil strength and it was similar to the failure zone which is considered in theory. Considering the shape of load-settlement curves obtained by numerical analyses, punching shear failure can be seen in loose sand and ultimate bearing load can not be seen in dense sand whereas, yielding point can be seen in clay. Ultimate bearing loads for sand predicted by theory were greater than those obtained by numerical analyses and ultimate bearing loads for clay predicted by theory were similar to those of numerical analyses. Ultimate bearing loads determined by 1 inch settlement criteria were slightly less than those of numerical analyses.

• Journal of Korean Medical classics
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• v.24 no.5
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• pp.1-10
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• 2011

According to "Dongeuibogam(東醫寶鑑)", "the Shinnong Herb Bible(神農本草經)", "Chamdonggo(參同攷)", come to the conclusion about medical thought of "the Zhouyi Cantongxie(周易參同契)". Alchemy is a common field both on the eastern and western civilization, but a process of development is different. Ancient chinese alchemist made a study on external alchemy, but harmful consequences of external alchemy was consecutive, many scholars had turned their interest on internal alchemy which is related in human meridian biology and spirit. In the western alchemy has developed to make a study on analytic psychology and science of religion. Most importantly, the eastern and western alchemy have something in common what at the point of the perfection of self is similar, but the name is different, for example in the eastern alchemy we can be immortals and take a spiritual enlightenment with the elixir of life, in the western we can take a cure of souls as a christian. As for internal alchemy, "Cantongxie(參同契)" gives influence to the theories such as the theory of danjeon(lower part of the abdomen), evolution, aging, and life nurturing. Especially, the theory of danjeon shows such merit for studying since it is similar to triple energizers(三焦) and the theory of qi street(氣街) of oriental medicine. The study on "Cantongxie(參同契)" was achieved in Korea too, especially Chosun dynasty. "Candongkao (參同攷)" by Seo Myung-eung(徐命膺, 1716~1787) are representative. According to "Candongkao(參同攷)", Geon(乾), Gon(坤), Gam(坎), and Ri(離), the four trigrams for divination, each are affiliated with lungs, spleen, kidneys, and heart. Nowadays the study on alchemy correspond with modern trends, which are anti-aging and living without any disease. If processed mineral drugs is assured for stability, it can be used for incurable diseases such as cancer.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.1
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• pp.41-48
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• 1992

Various soil behaviors usually occurring in the geotechnical problems, such as, cutting and embankments, stability of slope, seepage, consolidations, shearing failures and liquefaction, should be predicted and analyzed in any way. An approach of these predictions may be followed by the development of the constitutive equations as first and subsequently solved by numerical methods. The purpose of this paper is develop the constitutive equation of sands uder monotonic or cyclic loadings. The constitutive equation which is based on elasto-plastic theory, modified anisotropic consolidated stress parameter by Sekiguchi et al and Pender's theory is derived. And the equation is included a new stress parameter, hardening function, Bauschinger's effects and Pender's theory. The model is later evaluated and confirmed the validity by the test data of Ottawa sand, Banwol sand Hongseong sand. The following conclustions may be drawn: 1. The consititutive equation which is based on elasto-plastic theory, modified anisotropic consolidated stress parpameter by Sekiguchi et al and Pender's theory is derived. The equation in included a new stress parameter, hardening function, Bauschinger's effect and Pender's theory. 2. For Ottawa sand, the result of the constitutive equation shows a better agreement than that of Oka et al. The result of axial strain agrees well with the tested data. However, the result of horizontal strain is little bit off for the cyclic loadings or large stress. It is thought that the deviation may be improved by considering Poisson's ratio and precise measurement of shear modulus. 3. Banwol sand is used for the strain and stress tests with different relative densitites and confining pressures. The predeicted result shows a good agreement with the tested data because the required material parameters were directly measurd and determined form this laboratory. 4. For Hongseong sand, the tests under same amplitude of cyclic deviatoric stress shows a similar result with the tested data in absolute strain. It shows the acute shape of turning point because the sine wave of input is used in the test but the serrated wave in prediction.

• Journal of Society of Preventive Korean Medicine
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• v.23 no.3
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• pp.83-107
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• 2019

Objective : We compare the nurturing theories of Between the Nurturing Theory of Dogyogwonseonseo(道敎勸善書) JeungjungGyeongsinrok(增訂敬信錄), Gyeongsinrokeonseok(敬信錄諺釋), Taisanggauempyeondosul(太上感應篇圖說) and Guahwajonsin(過化存神) vs Dongui-Susebowon-Sasang-Chobongwon(東醫壽世保元四象草本卷) and Dongui-Susebowon(東醫壽世保元) of Lee-Jema. And the influences that Dogyogwonseonseo had on Nurturing Theory of Lee-Jema. Method : We sort out the identical or similar vocabularies and abstract the important concepts from all four kinds of Dogyogwonseonseo and two kinds of Lee-Jema's books mentioned above and compare them respectively. The prehistories of vocabularies and concepts needed such as Bok(福, good fortune) and Su (壽, longevity) will be traced. And the synchronic understanding needed such as 'Good deed leads to longevity and good fortune whereas evil deed leads to short life' in late Choseon dynasty will be surveyed by investigating the controversy of the time. Results : The Nurturing Theory of Lee-Jema was influenced by all four kinds of Dogyogwonseonseo mentioned above. We can ascertain the influence from Lee-Jema's Concept of Myeong(命), Nurturing Life through everyday life, 'Good deed leads to longevity and good fortune whereas evil deed leads to short life', deceiving mind(詐心), betraying mind(欺負心) and the jealousy of Man and Woman. Conclusion : The influences Dogyogwonseonseo had on Lee-Jema's nurturing theory were key concept words such as Myeong(命), the ways of thinking like 'Good deed leads to longevity and good fortune whereas evil deed leads to short life' and vocabularies such as deceiving mind(詐心).

• Korean Journal of Remote Sensing
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• v.21 no.2
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• pp.145-162
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• 2005

To improve the accuracy of land-cover discrimination in SAB data classification, this paper presents a methodology that includes feature extraction and fusion steps with multi-temporal SAR data. Three features including average backscattering coefficient, temporal variability and coherence are extracted from multi-temporal SAR data by considering the temporal behaviors of backscattering characteristics of SAR sensors. Dempster-Shafer theory of evidence(D-S theory) and fuzzy logic are applied to effectively integrate those features. Especially, a feature-driven heuristic approach to mass function assignment in D-S theory is applied and various fuzzy combination operators are tested in fuzzy logic fusion. As experimental results on a multi-temporal Radarsat-1 data set, the features considered in this paper could provide complementary information and thus effectively discriminated water, paddy and urban areas. However, it was difficult to discriminate forest and dry fields. From an information fusion methodological point of view, the D-S theory and fuzzy combination operators except the fuzzy Max and Algebraic Sum operators showed similar land-cover accuracy statistics.

• Information Systems Review
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• v.19 no.3
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• pp.179-199
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• 2017

As users' cross-over shopping behaviors become more popular, many studies have attempted to describe a theoretical mechanism in multichannel environments. Apart from explaining a simplified multichannel user behavior, relevant researchers must deeply understand the mechanism of users' cross-over shopping behavior, which cannot be discovered by employing either existing theories or traditional research methods. Thus, this study explores why, how, and when users conduct cross-over shopping behaviors in multichannel environments by employing a grounded theory approach. In this study, we have interviewed 25 participants who have prior experiences in cross-over shopping. By analyzing the interview manuscripts using the grounded theory approach, we have extracted 118 codes in the coding steps and ultimately presented 28 categories by incorporating similar concepts from those codes. In this qualitative grounded theory study, we have discussed why, how, and when users do cross-over shopping behavior based on our selected codes and categories as well as by listening to the stories of our interviewees. By grounding our proposed framework, which can capture both dynamic information search and purchasing behavior, this study provides an alternative research approach to explain user behavior, thereby bolstering our current understanding of the cross-over shopping behavior of users in multichannel environments.