• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.122-129
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• 2015

In this study, a prediction model for the effective compressive strength of corner columns with intervening normal strength concrete slabs was developed. A structural analogy between high-strength concrete column-normal strength concrete slab joint and brick masonry was used to develop the prediction model. In addition, the aspect ratio of slab thickness to column dimension was considered in the models. The reliability of the new prediction model was evaluated by comparison with experimental results and its superiority was demonstrated by comparison with previous models proposed by design codes and other researchers. As a result, with average test-to-predicted ratios of 1.09, a standard deviation of 0.15, the newly developed equation provided superior predictions in terms of accuracy and consistency over all of the existing effective strength prediction approaches including KCI structural concrete design code (2012).

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.1-8
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• 2014

The present study proposes a simple equation to straightforwardly determine the potential plastic hinge length in boundary element of reinforced concrete shear walls. From the idealized curvature distribution along the shear wall length, a basic formula was derived as a function of yielding moment, maximum moment, and additional moment owing to diagonal tensile crack. Yielding moment and maximum moment capacities of shear wall were calculated on the basis of compatability of strain and equilibrium equation of internal forces. The development of a diagonal tensile crack at web was examined from the shear transfer capacity of concrete specified in ACI 318-11 provision and then the additional moment was calculated using the truss mechanism along the crack proposed by Park and Paulay. The moment capacities were simplified from an extensive parametric study; as a result, the equivalent plastic hinge length of shear walls could be formulated using indices of longitudinal tensile reinforcement at the boundary element, vertical reinforcement at web, and applied axial load. The proposed equation predicted accurately the measured plastic hinge length, providing that the mean and standard deviation of ratios between predictions and experiments are 1.019 and 0.102, respectively.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.63-74
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• 2014

Predicting protein loop structures is an important modeling problem since protein loops are often involved in diverse biological functions by participating in enzyme active sites, ligand binding sites, etc. However, loop structure prediction is difficult even when structures of homologous proteins are known due to large sequence and structure variability among loops of homologous proteins. Therefore, an ab initio approach is necessary to solve loop modeling problems. One of the difficulties in the development of ab initio loop modeling method is to derive an accurate scoring function that closely approximates the true free energy function. In particular, entropy as well as energy contribution have to be considered adequately for loops because loops tend to be flexible compared to other parts of protein. In this study, the contribution of conformational entropy is considered in scoring loop conformations by employing "colony energy" which was previously proposed to estimate the free energy for an ensemble of conformations. Loop conformations were generated by using two EDISON_Chem programs GalaxyFill and GalaxySC, and colony energy was designed for this sampling by tuning relevant parameters. On a test set of 40 loops, the accuracy of predicted loop structure improved on average by scoring with the colony energy compared to scoring by energy alone. In addition, high correlation between colony energy and deviation from the native structure suggested that more extensive sampling can further improve the prediction accuracy. In another test on 6 ligand-binding loops that show conformational changes by ligand binding, both ligand-free and ligand-bound states could be identified by using colony energy when no information on the ligand-bound conformation is used.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.12 s.255
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• pp.1203-1210
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• 2006

The filmwise condensation heat transfer coefficients of R-134a on the horizontal copper and stainless steel tubes were measured and analyzed. The outside diameter of the tubes was 15.88 mm, and the tube thickness ranged from 0.89 to 1.65 mm. The polished stainless steel tube had an RMS surface roughness($R_q$) of 0.37 $\mu$m, and commercial stainless steel tubes had an surface roughness($R_q$) of 1.855 $\mu$m. The tests were conducted at the saturation temperatures of 20 and $30^{\circ}C$, and the liquid wall subcoolings from 0.4 to $2.1^{\circ}C$. The measured condensation heat transfer coefficients were significantly lower than the predicted data by the Nusselt analysis. This trend in the stainless steel tube was explained by the effects of thermal resistance of tube material and surface roughness. Based on the experimental data with respect to wall thickness and surface roughness, it was suggested that the existing correlation on external condensation should be modified by considering material and surface roughness factors. The revised correlation was developed by introducing the effects of wall thickness and surface roughness into the Nusselt equation. The average deviation of the revised correlation was 13.0 %.

• Journal of Astronomy and Space Sciences
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• v.9 no.1
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• pp.41-51
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• 1992

Photoelectric observations of close binary stars, AO Cam and AW Cam, were made during the 1984 observing season with the 61cm reflector at the Sobaeksan Observatory. One time of primary minimum for AO Cam and three primary epochs for AW Cam were derived from the observations of these two systems. Times of minimum light of these two binaries collected from literature were analyzed with a least square fitting method. New improved light elements for AO Cam and AW Cam were determined. The orbital period of AO Cam had been constant from Octobar, 1980 (JD 244520) to February, 1985 (JD 2446107). However, one secondary time of minimum (JD 2447864.7879) of AO Cam published recently by Mullis and Faulkner(1991) shows large deviation of about 4.6 minutes ($0^d.0032$) from the one predicted by our new light elements. Future observations of times of minima for this system are needed to test this period change. The orbital period of AW Cam has been constant as P=$0^d.77134645$ for about sixty years from the early 1930's to the present.

• Composites Research
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• v.26 no.2
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• pp.91-98
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• 2013

A three-dimensional finite analysis method was proposed to predict the failure of composite double-lap bolted joints, which is based on the stiffness degradation method using damage variables and Hashin's three-dimensional failure criteria. Ladeveze's theory using damage variables to consider the matrix/shear damage was combined with stiffness degradation in fiber direction. Four different failure modes were considered including matrix compression/shear, matrix tension/shear, fiber compression, and tension failures. The friction between bolt and composite and the clamping force were considered using a commercial finite element software ABAQUS. The damage model was incorporated using the user-defined subroutine of the software. The predicted result was verified with the existing test result for bearing tension double shear and showed the deviation ranging 7~16% from test results.

• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.765-772
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• 2011

The present study summarizes a series of compressive tests on concrete cylinder in order to examine the stressstrain relationship of alkali-activated (AA) slag concrete. The compressive strength and unit weight of concrete tested ranged from 8.6 MPa to 42.2 MPa and from $2,186kg/m^3$ to $2,343kg/m^3$, respectively. A mathematical equation representing the complete stress-strain curve was developed based on test results recorded from 34 concrete specimens. The modulus of elasticity, strain at peak stress, slopes of ascending and descending branches of stress-strain curves were generalized as a function of compressive strength and unit weight of concrete. The mean and standard deviation of the coefficient of variance between measured and predicted curves were 6.9% and 2.6%, respectively. This indicates that the stress-strain relationship of AA slag concrete is represented properly with more accuracy in the proposed model than in some other available models for ordinary portland cement (OPC) concrete.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.2
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• pp.218-227
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• 2014

In this paper, it performed to the elastic-plastic large deflection series analysis using the experimental model and predicted a failure mode and ultimate strength. The collapse mode of numerical analysis model is formed a plastic hinge on loaded flange and consistent with the collapse mode of experimental model. Also, The yield line is formed in the web could observed that have occurred the crippling collapse mode and the ultimate loads of the experimental model and numerical analysis model have maintained linearly Means 1.07, Standard deviation 0.04, Coefficient of variation(COV) 0.04 and the result of ultimate loads have appeared approximately 8% error rate. it was found that very satisfied to the experimental results and the applied rules. if it is considered to be maintain a reasonable safety level, it is possible to predict the failure modes of aluminium alloy plate girders and ultimate loads.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.2
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• pp.525-538
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• 2016

This study is to investigate the effect of the amusement factor and the motive of participation in skin-scuba class on the satisfaction with university life with the university students participating in the skin-scuba class and to provide the practical research data for the development of the marine sports, for the proper operation of skin-scuba class, and for the leisure life which the university students may lack. For these purposes, technical statistics between questions were disposed in order to grasp the average and standard deviation on each variables, exploratory factor analysis and reliability analysis were conducted for the reliability and validity of the scale, and correlation analysis and multiple regression analysis were conducted to test the casuality of amusement factor, the motive of participation in skin-scuba class and the satisfaction with university life as the research methods. Research results showed that it was confirmed that the amusement factor and the motive of participation in skin-scuba class act as the important variables in the satisfaction with university life and it was predicted that the motive of participation in skin-scuba class and the amusement factor had interrelation with parameter. Therefore, a variety of programs reflecting the amusement factors should motivate the university students to particiapte in the skin-scuba class to increase the satisfaction with university life and to encourage the re-participation of students.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.4
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• pp.195-201
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• 2017

In this study, the viscosity of a $CO_2-gas$ mixture was investigated for the transportation of the captured $CO_2-gas$ in pipelines and for the designing of a thermal system, both of which involve the utilization of the $CO_2-gas$ mixture. The viscosities of the $CO_2-gas$ mixture, $CO_2+CH_4$, $CO_2+H_2S$, and $CO_2+N_2$ were predicted using three different models as follows : Chung, TRAPP, and REFPROP. The predictability values of the models were validated by comparing the estimated results with the experiment data for the $CO_2+CH_4$ and $CO_2+N_2$ under high-density conditions. The Chung model showed 2.41%, which is the lowest mean deviation of the prediction among the model. Based on the Chung model, the mixture mole fractions were changed from 0.9, 0.95, and 0.97, the mixture pressure was ranged from 80 bar to 120 bar by 10 bar, and the mixture temperature was varied from 310 K to 400 K by 10 K to observe the effects of the parameters on the mixture viscosity. Considering the high mole fraction of the $CO_2$ in the mixture, a significant variation of the mixture viscosity was observed close to the pseudo-critical temperature, and the viscosity for the $CO_2+H_2S$ mixture shows the highest values compared with those of the $CO_2+CH_4$ and $CO_2+N_2$.