• Journal of Korean Society of Steel Construction
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• v.21 no.6
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• pp.609-618
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• 2009

This paper proposes a versatile formula which can be used to evaluate the fire resistant time of steel beams under various design conditions. Towards this end, the key parameters which affect the fire performance of steel beams were first determined through thermo-mechanical considerations, and classified into two groups: structural parameters and thermal parameters. Then the degree of influence of each parameter on the fire performance was investigated through a fully coupled thermo-mechanical analysis up to the occurrence of run-away deflection. The accuracy of the numerical model used was verified using an available full-scale fire test before conducting an extensive parametric analysis. Multiple linear regression analysis was performed to obtain the formula which can be used to predict the fire resistance time of steel beams under various design conditions. The statistical analysis showed that the proposed formula is very robust. The application of the formula in practical fire design under the current code was illustrated in detail. The economy and other advantages of the proposed formula were clearly shown.

• Steel and Composite Structures
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• v.13 no.5
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• pp.409-421
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• 2012

Recently, as the height of building is getting higher, the applications of CFST column for high-rise buildings have been increased. In structural system of high-rise building, The RC core and exterior concrete-filled tubular (CFST) column-beam pinned connection is one of the structural systems that support lateral load. If this structural system is used, due to the minimal CFST column thickness compared to that of the CFST column width, the local moment occurred by the eccentric distance between the column flange surface from shear bolts joints degrades the shear strength of the CFST column-beam pinned connections. This study performed a finite element analysis to investigate the shear strength under eccentric moment of the CFST column-beam pinned connections. The column's width and thickness were used as variables for the analysis. To guarantee the reliability of the finite element analysis, an actual-size specimens were fabricated and tested. The yield line theory was used to formulate an shear strength formula for the CFT column-beam pinned connection. the shear strength formula was suggested through comparison on the results of FEM analysis, test and yield lime theory, the shear strength formula was suggested.

• Journal of Power Electronics
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• v.18 no.3
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• pp.746-756
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• 2018

Harmonic resonance exists in grid-connected inverter systems. In order to determine the network components that contribute to harmonic resonance and the composition of the resonant circuit, sensitivity theory is applied to the resonance characteristic analysis. Based on the modal analysis, the theory of sensitivity is applied to derive a formula for determining the sensitivities of each network component parameter under a resonance circumstance that reflects the participation of the network component. The solving formula is derived for both parallel harmonic resonance and series harmonic resonance. This formula is adopted to a 4-node grid-connected test system. The analysis results reveal that for a certain frequency, the participation of parallel resonance and series resonance are not the same. Finally, experimental results demonstrate that the solving formula for sensitivity is feasible for grid-connected systems.

• Journal of Nutrition and Health
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• v.18 no.1
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• pp.46-54
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• 1985

Three types of infant food were experimentally prepared based on the average caloric requirement for, Koreans : Formula A, with 1/3 RDA for 4-6 month, formula B, with 1/2 RDA for 7-9 month, and formula C, with 2/3 RDA for 10-12 month old infants. Into each formula was added approximately 50% of rice. Analysis of the nutritive values on these formula showed no deviance Com the expected values in case of general nutrients while the percent of essential amino acids in protein was muck higher except methionine. Since iron content was found to be below the half of except values, a sufficient amount of iron as required in RDA should be additionally supplied, for example, in iron drops. The infant preference test on each formula showed much favorable acceptability : 50% of them responded as moderate, 33.3% as favorable, 12.5% as disliking, and 4.2% as disgusting. The test also showed no noticeable change in both feces and appetite.

• Herbal Formula Science
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• v.22 no.1
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• pp.33-45
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• 2014

Objectives : Zizyphi spinosi Semen is widely used for treating insomnia in korea and other oriental country. This study is analyzing combination tendency of Zizyphi spinosi Semen in herbal formula for treating insomnia. Methods : Herbal formulas for treating insomia were searched in "The Prescription Dictionary of Traditional Chinese Medicine", and checked in each literary source. Then, the herbal formula was divided in two groups : FCZ(The formula group containing Zizyphi spinosi Semen) and FWZ(The formula group without Zizyphi spinosi Semen). FCZ and FWZ were compared by following criteria; i) Prevalence of herbal formula by period ii) Prevalence of medicinal material's effects iii) Prevalence of medicinal material iv) Prevalence of the nature of midicinals v) Prevalence of flavor of medicinals vi) Prevalence of meridian entry. Results : 116 Herbal formula met our criteria, and herbal formulas were divided in two groups : FCZ(n=59), FWZ(n=57). The result of prevalence in FCZ is following; Herbal formula prevalence increased as time passed to the Qing(淸) dynasty. Tonifying and replenishing medicinal(補益藥), tranquillizing medicinal (安神藥), and inducing diuresis to drain dampness medicinal(利水滲濕藥) are the three most prevalent types of materia medica. In specifically, Panax ginseng radix(人蔘), Liriopis Tuber(麥門冬), Angelicae Gigantis Radix(當歸), Poria Cocos(茯神), Glycyrrhizae Radix(甘草), Poria cocos(茯神), Polygalae Radix(遠志), Thuja Orientalis L.(柏子仁), Paeonia Japonica(白芍藥), and HgS(硃砂) are combined frequently. The most prevalent nature of medicinals were 'warm microwarm(溫 微溫)' and flavor of medicinals was normal(平). Meridian entrys that frequently combined were heart(心), spleen(脾), and liver(肝). Conclusion : We found combination tendency of Zizyphi Semen in herbal formula for treating insomnia.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.677-680
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• 2004

This study investigates the buckling evaluation of connecting rods used in the diesel engine through finite element analysis. The Rankine formula, which is modified from classical Euler‘s formula, has been widely accepted in automotive industry to evaluate the buckling of connecting rods. Apparently, this formula is most suitable for the straight and idealized rod shape, and over-simplifies the geometric complexity associated with connecting rods. The subspace iteration method in FEA is used to predict the critical buckling stress of a connecting rod with certain slenderness ratio. To create models with various slenderness ratios for shank portion in the rod, the automatic meshing preprocessor was implemented. Results from FEA were verified by the experiments, in which the embedded strain gages measured for the connecting rod running at 4000rpm. The result indicates that the buckling prediction curve through FEA and experiment is effectively different from the curve of classical Rankine formula.

• Journal of Ocean Engineering and Technology
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• v.34 no.2
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• pp.97-109
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• 2020

In this study, ultimate strength characteristics of clamped sandwich panels with metal faces and an elastic isotropic core under combined in-plane compression and lateral pressure loads are investigated to verify the applicability of the ultimate strength design formula for ship structures. Alternative elastomer-cored steel sandwich panels are selected instead of the conventional bottom stiffened panels for a Suezmax-class tanker and then the ultimate strength characteristics of the selected sandwich panels are examined by using nonlinear finite element analysis. The change in the ultimate strength characteristics due to the change in the thickness of the face plate and core as well as the amplitude of lateral pressure are summarized and compared with the results obtained by using the ultimate strength design formula and nonlinear finite element analysis. The insights and conclusions developed in the present study will be useful for the design and development of applications for sandwich panels in double hull tanker structures.

• Nuclear Engineering and Technology
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• v.30 no.4
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• pp.287-297
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• 1998

The elastic stiffness formula of leaf type holddown spring(HDS) assembly is verified by comparing the values of elastic stiffness with the characteristic test results of the HDS's specimens. The comparisons show that the derived elastic stiffness formula is useful in reliably estimating the elastic stiffness of leaf type HDS assembly. The elastic stiffness sensitivity of leaf type HDS assembly is analyzed using the formula and its gradient vectors obtained from the mid-point formula. As a result of sensitivity analysis, the elastic stiffness sensitivity with respect to each design variable is quantified and design variables of large sensitivity are identified. Among the design variables, leaf thickness is identified as the most sensitive design variable to the elastic stiffness of leaf type HDS assembly. In addition, the elastic stiffness sensitivity, with respect to design variable, is in power-law type correlation to the base thickness of the leaf.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.6
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• pp.29-36
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• 2012

Involved in a research for the application of seismic isolation to the nuclear industry, this study evaluates firstly the responses of seismic isolation system considering general ranges of structural period and damping ratio by using preliminary design formula. Secondly, coupling effects of input motions were evaluated to find out appropriate conditions of excitations and effect of the iteration for calculating yield displacement of lead core was also assessed in terms of response of a seismically isolated structure. Finally, the results of preliminary design calculation were compared with those of dynamic analysis and the propriety of the formula was evaluated and appropriate ranges of reduction factor were also suggested from the results.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.77-78
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• 2002

A regression formula including the inlet film thickness as the parameter for the starvation factor in EHL condition is obtained by numerical analysis with Elord‘s cavitation algorithm. In addition, an apparatus for starved film thickness measurement by use of the white light interferometry is developed in order to verify the proposed regression formula. From observation results by this apparatus, the proposed regression formula can predict the reduction of central film thickness caused by starvation in a ball-plate contact with an uncertainty up to 10%