• Journal of the Korean Home Economics Association
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• v.41 no.6
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• pp.91-104
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• 2003

Using the 1998 Survey of Consumer Finances(SCF), this study examined the factors associated with the probability of saving by female-headed households in the U.S, and investigated how these factors differ by life cycle stages. Age of children, age of female householders and their retirement status were used to categorize three life cycle stages: first stage - have at least one child under age 18; second stage - under the age of 62 and have no children under age 18; third stage - over the age of 62 and retired. Logistic regression analysis results indicated that those with higher education and income and who were White were more likely to save. An interactive model showed that life cycle stages were significantly related to saving decisions. Female-headed households in the first stage or the third stage were less likely than those in the second stage (reference group) to save. For female-headed households in the first stage and the third stage, the amount of income had significantly positive effects on the decision to save. Also, in the group of households in the first stage, the receipt of welfare assistance increased the probability of saving.

• Journal of Ocean Engineering and Technology
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• v.8 no.2
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• pp.141-150
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• 1994

In designing, the strength of tubular joint has been an important problem for integrity of steel structures in which many tubular members are used. This paper presents the results of FEM analysis on stress concentration and fatigue crack initiation life for two types of tubular joints. One is circular and rectangular T type joints which consist of circular brace and rectangular chord. Another is circular and circular T type joints which consist of circular brace and circular chord. FEM analyses were performed under the axial load and in-plane bending moment. The fatigue crack initiation life can be estimated by using $\varepsilon$-N curve and by applying the Palmgren-Miner linear damage rule. According to the results, the stress concentration factor(SCF) of circular and rectangular joints is higher than that of circular and circular joints. The fatigue crack initiation lives of circular-circular joints and circular-rectangular joints were calculated.

• Bulletin of the Korean Chemical Society
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• v.19 no.8
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• pp.847-851
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• 1998

13C, 15N, and 29Si NMR chemical shifts have been computed for selected X-substituted silatranes (X=Cl, F, H, CH3) using Gauge-Including Atomic Orbitals (GIAO) and Continuous Set of Gauge Transformations (CSGT) at the Hartree-Fock level of theory. The isotropic 13C chemical shifts are largely insensitive to substituent-induced structural changes. In this study, the isotropic 13C chemical shifts GIAO and CSGT calculations at the HF/6-31G and HF/6-31G* levels are sufficiently accurate to aid in experimental peak assignments. The isotropic 13C chemical shifts X-substituted silatranes at HF/6-31G* level are approximately 4 ppm different from the experimental values. In contrast, the isotropic 15N and 29Si chemical shifts and the chemical shielding tensors are quite sensitive to substituent-induced structural changes. These trends are consistent with those of the experiment. The 15N chemical shift parameters demonstrate a very clear correlation with Si-N distance, especially when we use the polarization function. Changes in anisotropy, 3a as well as in the 15N isotropic chemical shifts are due primarily to changes in the value of a.. But in case of "Si the correlations are not as clean as for the 15N chemical shift.

• Bulletin of the Korean Chemical Society
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• v.20 no.11
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• pp.1281-1287
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• 1999

The low-lying electronic states of diazirine and 3,3'-dimethyldiazirine have been studied by high level ab initio quantum chemical methods. The equilibrium geometries of the ground state and the first excited singlet and triplet states have been optimized using the Hartree-Fock (HF) and complete active space SCF (CASSCF) methods, as well as using the Møller-Plesset second order perturbation (MP2) theory and the single configuration interaction (CIS) theory. It was found that the first excited singlet state is of 1 B1 symmetry resulting from the n- π* transition, while the first excited triplet state is of 3 B2 symmetry resulting from the π- π* transition. The harmonic vibrational frequencies have been calculated at the optimized geometry of each electronic state, and the scaled frequencies have been compared with the experimental frequencies available. The adiabatic and vertical transition energies from the ground electronic state to the low-lying electronic states have been estimated by means of multireference methods based on the CASSCF wavefunctions, i.e., the multiconfigurational quasidegenerate second order perturbation (MCQDPT2) theory and the CASSCF second-order configuration interaction (CASSCF-SOCI) theory. The vertical transition energies have also been calculated by the CIS method for comparison. The computed transition energies, particularly by MCQDPT2, agree well with the experimental observations, and the electronic structures of the molecules have been discussed, particularly in light of the controversy over the existence of the so-called second electronic state.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.6
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• pp.429-437
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• 2018

The process gas piping of the offshore plant can cause a massive explosion if the gas leakage occurs during operation. For the purpose of precaution of gas leakage accident, an air pressure test is performed on the process equipment tests using a test pump as much as the power to the piping inner side, mix 99% nitrogen gas and 1% helium gas. The purpose of the air pressure test is to check the work conformity process by handling and regulation for initial piping process, assembly, installation of module, welding, center alignment of the pipes assembling flange gasket in an unrestrained free state. In this paper, the regulation of the problematic air pressure test was analyzed and the solution criteria were established. And leakage tests of existing equipment were performed applying these solution methods. As a result, it was confirmed that there was no problem.

• Bulletin of the Korean Chemical Society
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• v.14 no.2
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• pp.244-250
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• 1993

The interaction of 1,3,5-trithian molecule with Ag(111) surface is studied employing Extended Huckel method. The Ag(111) surface is modeled by the three layer metal clusters composed of 43 Ag atoms. We assume that the 1,3,5-trithian is lying flat on Ag(111) surface in the chair conformation. The geometry of 1,3,5-trithian itself is assumed to be the same as in the gas phase, which is obtained through the AM1 SCF-MO calculation with full geometry optimization. The calculation for 3-fold site adsorption leads to the weakening of C-S bond, which is compatible with the observed 5 cm$^{-1}$ decrease of the C-S stretching frequency upon surface adsorption, while the on-top site adsorption leads to strengthening of C-S bond. The major component of the C-S bond of trithian is S $3p_{pi}\;(S\;3p_x+S\;3p_y)$ and therefore only the 3-fold site adsorption causes the weakening of this bond. In addition, it is found that the trithian molecule binds to the 3-fold site more strongly.

• Structural Engineering and Mechanics
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• v.88 no.5
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• pp.463-480
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• 2023

The buckling-restrained braced frames with eccentric configurations (BRBF-Es) exhibit stable cyclic behavior and possess a high energy absorption capacity. Additionally, they offer architectural advantages for incorporating openings, much like Eccentrically Braced Frames (EBFs). However, studies have indicated that significant residual drifts occur in this system when subjected to earthquakes at the Maximum Considered Earthquake (MCE) hazard level. Consequently, in order to mitigate these residual drifts, it is recommended to employ self-centering systems alongside the BRBF-E system. In our current research, we propose the utilization of the Direct Displacement-Based Seismic Design method to determine the design base shear for a hybrid system that combines BRBF with an eccentric configuration and a self-centering frame. Furthermore, we present a methodology for designing the individual components of this composite system. To assess the effectiveness of this design approach, we designed 3-, 6-, and 9-story buildings equipped with the BRBF-E-SCF system and developed finite element models. These models were subjected to two sets of ground motions representing the Maximum Considered Earthquake (MCE) and Design Basis Earthquake (DBE) seismic hazard levels. The results of our study reveal that although the combined system requires a higher amount of steel material compared to the BRBF-E system, it substantially reduces residual drift. Furthermore, the combined system demonstrates satisfactory performance in terms of story drift and ductility demand.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.1
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• pp.241-246
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• 2003

Bambusae Caulis in Liquamen(BCL) has been used to relieve the cough and asthma, and remove the phlegm in traditional Oriental medicine. In recent years, it was studied for its antiinflammatory, antiallergenic, immune-modulating, and anticarcinogenic capabilities. This experiment was performed to evaluate the microarray profiles of CD genes in human mast cells before and after BCL treatment. The results are as follows: The expression of 51 of the genes studied was up-regulated in the Bel-treated group; they include the genes coding L apoferritin, beta-2-microglobulin, ferritin light polypeptide, CD63, monocyte chemotactic and activating fact, heme oxygenase 1, CD140a, integrin alpha M, colony stimulating factor 2 receptor, eukaryotic translation elongation factor, CD37, interleukin 18, NADH dehydrogenase 1 beta, CD48, 5-lipoxygenase activating protein, interleukin 4, ribosomal protein L5, GABA(A) receptor-associated protein, beta-tubulin, integrin beta 1, CD162, CD32, lymphotoxin beta, alpha-tublin, integrin alpha L, CD2, CD151, CD331, 90 kDa heat shock protein, CD59, CD3Z, microsomal glutathione S-transferase 2, CD33, CD162R, cyclophilinA, CD84, interleukin 9 receptor, interleukin 11, CD117, CD39-Like 2, and so forth. The expression of 7 of the genes studied was down-regulated in the BCL-treated group; they include the genes coding con, CD238, SCF, CD160, CD231, CD24, and CD130. Consequently, the treatment of BCL on the human mast cells increased the expression of 51 genes and decreased the expression of 7 genes. These data would provide a fundamental basis to the traditional applications of Bambusae Caulis in Liquamen.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.78-78
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• 2003

Adult stem cells can make identical copies of themselves for long periods of time. They also give rise to many differentiated mature cell types that have characteristic morphology and specialized function. Human adult stem cells are the attractive raw materials for the cell/tissue therapy, however, it is not easy to get from the adult tissues. In the present study, we tried to isolate a cell population derived from human umbilical cord vein which has been discarded after birth. The cells were isolated after treatment of the umbilical vein with collagenase or trypsin. After 3 days of culture, two kinds of cell populations were found consisting of adherent cells with endothelial cell-like and fibroblast-like morphology, respectively. When these cells were subcultured 12 times over a period of 3 months, almost cells appeared uniformly to exhibit fibroblastoid morphology which was different from that of mesenchymal stem cells obtained from human bone marrow The results of RT-PCR analyses showed distinct expression of BMP-4, oct-4, and SCF genes but not of GATA, PAX-6 and Brachyury genes. On immunohistochemical staining, the cells were negative for the von Willebrand factor(vWF), alpha-smooth muscle actin and placental alkaline phosphatase. From these observations, it is suggested that stem-like cells might be present in human umbilical cord vein.

• Journal of Advanced Research in Ocean Engineering
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• v.1 no.4
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• pp.239-251
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• 2015

In this study, a spectral fatigue analysis was performed for the topside structure of an offshore floating vessel. The topside structure was idealized using beam elements in the SACS program. The fatigue analysis was carried out considering the wave and wind loads separately. For the wave-induced fatigue damage calculation, motion RAOs calculated from a direct wave load analysis and regular waves with different periods and unit wave heights were utilized. Then, the member end force transfer functions were generated covering all the loading conditions. Stress response transfer functions at each joint were produced using the specified SCFs and member end force transfer functions. fatigue damages were calculated using the obtained stress ranges, S-N curve, wave spectrum, heading probability of each loading condition, and their corresponding occurrences in the wave scatter diagrams. For the wind induced fatigue damage calculation, a dynamic wind spectral fatigue analysis was performed. First, a dynamic natural frequency analysis was performed to generate the structural dynamic characteristics, including the eigenvalues (natural frequencies), eigenvectors (mode shapes), and mass matrix. To adequately represent the dynamic characteristic of the structure, the number of modes was appropriately determined in the lateral direction. Second, a wind spectral fatigue analysis was performed using the mode shapes and mass data obtained from the previous results. In this analysis, the Weibull distribution of the wind speed occurrence, occurrence probability in each direction, damping coefficient, S-N curves, and SCF of each joint were defined and used. In particular, the wind fatigue damages were calculated under the assumption that the stress ranges followed a Rayleigh distribution. The total fatigue damages were calculated from the combination with wind and wave fatigue damages according to the DNV rule.