• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.315-318
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• 2009

Some particular bound state energies of an electron, under Coulomb potential field, confined in a two-dimensional circle and a three-dimensional sphere are analytically derived. The derivation shows that the electron cannot be bound in a negative energy state when the circle (or sphere) is smaller than a certain critical size. The critical size dependency on the strength of Coulomb potential and the angular momentum of the electron is also analytically derived. This system mimics quantum dots. Therefore the derivation provides new information on a minimum critical size of quantum dots with hydrogenic impurity.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.299-304
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• 1995

An equation is proposed to predict ultimate shear strength. The equatiion on ultimate shear strength, which is purely based on analytical premises, is similar form to ACI code(11-6) which is derived mainly from empirical approach. Furthermore, the strength predicted by the proposed equation show better correlation with the tested values than the values calculated by Zsutty's formula.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.236-239
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• 2004

The ternary blended cement(TBC) which the ability of resistance for seawater, the effect of decreation of hydration heat of concrete and long-age strength are known to be superior to other types was used to derive the estimation function of 91-age strength, 28-age strength with 28-age strength, 7-age strength respectively by analyzing the characteristics of statistics of compressive strength. The sample specimens was made after testing the variations of slump, air-contents during 30 minutes for consideration of transportation period. The functions might be expected to be useful for construction smoothness and reasonable quality control of concrete with TBC.

• Journal of Welding and Joining
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• v.32 no.2
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• pp.43-47
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• 2014

Famous artificial neural network (ANN) is applied to predict proper process window of arc welding. Target weldment is variously combined lap joint fillet welding of automotive steel plates. ANN's system variable such as number of hidden layers, perceptrons and transfer function are carefully selected through case by case test. Input variables are welding condition and steel plate combination, for example, welding machine type, shield gas composition, current, speed and strength, thickness of base material. The number of each input variable referred in welding experiment is counted and provided to make it possible to presume the qualitative precision and limit of prediction. One of experimental process windows is excluded for predictability estimation and the rest are applied for neural network training. As expected from basic ANN theory, experimental condition composed of frequently referred input variables showed relatively more precise prediction while rarely referred set showed poorer result. As conclusion, application of ANN to arc welding process window derivation showed comparatively practical feasibility while it still needs more training for higher precision.

• Journal of the Korean Professional Engineers Association
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• v.30 no.6
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• pp.113-120
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• 1997

This subject,'S" apartment structural frame has not been achieved without considerable effort by all quality controller involved. Therefore, it is appropriate at this time to report by all the fact of concrete quality control in our site. These are emphasized that the average strength of placed concrete must always exceed the specified value of design strength used in the structural design phase. In general, quality of ready mixed concrete largely depends not only upon the manner of production and proper observance of recognized methods of placement, finishing, curing, transportation etc. ,but also many kinds of influential factors even more handling of the test procedure, As this practical report, approaching to judgement by analysis of sampled specimens in site weather placed concrete have satisfied quality compare the specified strength with the target strength which is applied to standard deviation related with influential factors as above mentioned. This case study is consist of 1) A foreword, 2) Site brief, 3) A precondition for analysis, 4) A formulas derivation and quality analysis, 5) Economic gains by the coefRcient of increase and 6) A conclusion.sion.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.107-110
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• 2009

After inquiring into physical characteristics of using fly ash and alkali solution, it was found that higher pH density is favorable to strength development at early age and the higher the age is, the higher the compressive strength gets. Also, it was found that when there is more addition of activator, the compressive strength is higher. I was shown that more than atmospheric curing, steam curing was favorable for development of compressive strength. When the temperature of curing temperature was higher, most of the compressive strengths were higher. Thus, based on this study, it was understood that environmental-friendly chemically combined concrete using fly ash and alkali solution can be utilized without using cement.

• Steel and Composite Structures
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• v.6 no.5
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• pp.387-400
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• 2006

This paper discusses the composite mechanism and its effect upon the behavior of a steel reinforced concrete (SRC) member subjected to a flexural load. The relationship between member strength and deformation is established using the bond strength between the steel and reinforced concrete. An analytical model is proposed and used to incorporate the sectional strains and bond strength at the elastic and inelastic stages for moment-curvature relationship derivation. The results from the flexural load tests are used to validate the accuracy of the proposed model. Comparisons between the experimental information and the analytical results demonstrate close moment-curvature relevance, which justifies the applicability of the proposed method.

• Geomechanics and Engineering
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• v.10 no.3
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• pp.257-267
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• 2016

Charts are used extensively in slope practical application to meet the need of quick assessment of rock slope design. However, Charts for estimating the shear strength of the rock mass of a slope are considerably limited. In this paper, based on the Hoek-Brown (HB) criterion which is widely used in rock slope engineering, we present charts which can be used to estimate the Mohr-Coulomb (MC) parameters angle of friction ${\phi}$ and cohesion c for given slopes. In order to present the proposed charts, we firstly present the derivation of the theoretical relationships between the MC parameters and ${\sigma}_{ci}/({\gamma}H)$ which is termed the strength ratio (SR). It is found that the values of $c/{\sigma}_{ci}$ and ${\phi}$ of a slope depend only on the magnitude of SR, regardless of the magnitude of the individual parameters ${\sigma}_{ci}$(uniaxial compressive strength), ${\gamma}$(unit weight) and H (slope height). Based on the relationships between the MC parameters and SR, charts are plotted to show the relations between the MC parameters and HB parameters. Using the proposed charts can make a rapid estimation of shear strength of rock masses directly from the HB parameters, slope geometry and rock mass properties for a given slope.

• Journal of Ocean Engineering and Technology
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• v.37 no.1
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• pp.31-37
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• 2023

In this study, a fiber chain was developed to replace a steel chain using high-modulus polyethylene DM20. The pick count, wrapping count, and inner length were selected as the main design variables of the fiber chain and were analyzed to increase the breaking strength. Orthogonal array experiments were conducted, and the results were analyzed with respect to the breaking strength. The analysis revealed that the pick count and wrapping count had meaningful effects at significance levels within 5%. The main effect analysis revealed that a smaller pick count, larger wrapping count, and longer inner length caused the breaking strength to increase. With the wrapping count fixed at 1, a pick count less than -0.65, and an inner length greater than 0.38, the breaking strength was calculated to be greater than 300 kN. These results are expected be important factors in the derivation of an optimal combination of design variables to attain a fiber chain with a targeted strength.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.89-92
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• 1999

The purpose of this study is to evaluate the capability to use with cement admixture materials because Paper Sludge Ash consists of Si, Ca and Al which are chief content in Pozzolan. For the derivation of Pozzolanic reaction in Paper Sludge Ash, it is measured compressive strength on cement mortar which is replaced mixing of Paper Sludge Ash and inorganic admixture ; ie, gypsum, lime and slaked lime, regularly. In the result of test, the strength decrease remarkably when cement is only replaced with Paper Sludge Ash, but the strength is almost equal when cement is replaced with Paper Sludge Ash is mixed with inorganic admixture material in proportions of 5~15%. Consequently, It is possible to use Paper Sluge Ash with admixture materials of cement.