• The Korean Journal of Applied Statistics
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• v.30 no.6
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• pp.917-929
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• 2017

Korean income data obtained from Korea Labor Panel Survey shows excessive zeros, which may not be properly explained by the Tobit model. In this paper, we analyze the data using a zero-inflated Tobit model to incorporate excessive zeros. A zero-inflated Tobit model consists of two stages. In the first stage, individuals with 0 income are divided into two groups: genuine zero group and random zero group. Individuals in the genuine zero group did not participate labor market since they have no intention to do so. Individuals in the random zero group participated labor market but their incomes are very low and truncated at 0. In the second stage, the Tobit model is assumed to a subset of data combining random zeros and positive observations. Regression models are employed in both stages to obtain the effect of explanatory variables on the participation of labor market and the income amount. Markov chain Monte Carlo methods are applied for the Bayesian analysis of the data. The proposed zero-inflated Tobit model outperforms the Tobit model in model fit and prediction of zero frequency. The analysis results show strong evidence that the probability of participating in the labor market increases with age, decreases with education, and women tend to have stronger intentions on participating in the labor market than men. There also exists moderate evidence that the probability of participating in the labor market decreases with socio-economic status and reserved wage. However, the amount of monthly wage increases with age and education, and it is larger for married than unmarried and for men than women.

• Parasites, Hosts and Diseases
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• v.30 no.1
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• pp.33-42
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• 1992

Naegleria fowleri, a free-living amoeba commonly found in moist soil and fresh water, enters the body via the nasal mucosa and migrates along the olfactory nerve to t he brain, where it causes acute amoebic meningoencephalitis. In the present study 7 clones secreting monoclonal antibodies (McAbs) against N. fowleri were produced and the effector function of them was investigated. Their isotopes were IgGl (Nf 1, Nf 154), 19G3 (Nf 137) and 19A (Nf 1, Nf 2, Nf 256, Nf 279). Five McAbs (McAb Nf 2, Nf 279, Nf 27, Nf 154, Nf 137) were specific for N. fowleri by ELISA and recognized the antigenic determinants located on the trophoBoite surface by IFAT and immunoperoxidase stain. These aye McAbs had capacity to agglutinate N. fowleri trophozoites and inhibited the growth of the amoeba in culture medium. McAb Nf 2 inhibited proliferation of trophozoites in vitro significantly. Also the cytotoxicity of JV. fowleri against CHO cell was reduced in the presence of McAb Nf 2 and McAb Nf 154. From these results McAb Nf 2 was confirmed to weaken the virulence of the amoeba among 7 screened McAbs.

• Journal of Life Science
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• v.19 no.12
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• pp.1808-1814
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• 2009

In our previous study, a new herbal preparation (HemoHIM) was developed as a functional food for the radioprotection and immunomodulatory agents. In order elucidate the mechanism involved, we examined the effect of HemoHIM on the compound 48/80-induced histamine release, and on the phorbol 12-myristate 13-acetate (PMA)/calcium ionophore (A23187)-induced inflammatory cytokine secretion in HMC-1. The cell culture supernatants were harvested, and the cytokines (IL-4, IL-6, IL-8, TNF-$\alpha$, GM-CSF) in the supernatants were measured by enzyme-linked immunosorbent assay. The total RNA of the cells was extracted, and the cytokines or c-kit/tryptase/Fc$\varepsilon$RI's messenger RNA expressions were examined using reverse transcriptase polymerase chain reaction. Under low concentrations, HemoHIM inhibited histamine release in HMC-1 stimulated compound 48/80. Furthermore HemoHIM inhibited PMA/A23187-induced inflammatory cytokines' secreation or mRNA expression in a dose-dependent manner. But IL-8 secretion was not inhibited by low concentrayion of HemoHIM, respectively. The mRNA expression of c-kit and Fc$\varepsilon$RI were also inhibited in a dose-dependent manner. Tryptase mRNA expression was only inhibited by low concentration of HemoHIM. These results indicated that HemoHIM might be an useful agent for protection against allergy as well as immune modulation, especially since it is a relatively nontoxic natural product.

• Applied Biological Chemistry
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• v.40 no.2
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• pp.157-162
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• 1997

A novel compound, named YH-487, was synthesized by attaching the thiol and aminothiazole residue to $C_3$ and $C_7$ position of 7-aminocephalosporanic acid (7-ACA). The therapeutic efficacy on infected animals, pharmacokinetics in vivo and the effect on intestinal microflora of YH-487 were examined. The pharmacokinetics of YH-487 were similar to that of cefotaxime, a third generation ${\beta}-lactam$ antibiotics, in rat. Upon in vivo administration, YH-487 was predominantly delivered to kidney, and mostly excreted through kidney without making any metabolites. The therapeutic efficacy of YH-487 to animal infected with E. coli was three times and twenty times higher than that of cefotaxime and cefotiam, respectively, In vivo administration of YH-487 to Sprague-Dawley rats significantly decreased the population of intestinal gram negative species such as Enterobacteria and Barteroides. However, no significant changes were obseved in gram positive species such as Lactobacillus, Bifidobacteria and Staphylococcus. In addition, continuous administration of YH-487 did not increase the possibility to induce resistant strains in intestinal microflora.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.4
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• pp.398-405
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• 2001

The rivet joint has typical structural feature that can be initiation site for the fatigue crack due to the combination of local stress concentration around rivet hole and the moisture trapping. From a viewpoint of structural assurance, it is crucial to evaluate the size of crack around the rivet holes by appropriate nondestructive evaluation techniques. Lamb wave that is one of guided waves, offers a more efficient tool for nondestructive inspection of plates. The neural network that is considered to be the most suitable for pattern recognition has been used by researchers in NDE field to classify different types of flaws and flaw sizes. In this study, clack size evaluation around the rivet hole using the neural network based on the back-propagation algorithm has been tarried out by extracting some features from the ultrasonic Lamb wave for A12024-T3 skin panel of aircraft. Special attention was paid to reduce the coupling effect between the transducer and the specimen by extracting some features related to time md frequency component data in ultrasonic waveform. It was demonstrated clearly that features extracted from the time and frequency domain data of Lamb wave signal were very useful to determine crack size initiated from rivet hole through neural network.

• Journal of Korea Water Resources Association
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• v.47 no.3
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• pp.285-295
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• 2014

We applied the ISPSO-GLUE method, which integrates the Isolated-Speciation-based Particle Swarm Optimization (ISPSO) with the Generalized Likelihood Uncertainty Estimation (GLUE) method, to the uncertainty analysis of the Topography Model (TOPMODEL) and compared its performance with that of the GLUE method. When we performed the same number of model runs for the both methods, we were able to identify the point where the performance of ISPSO-GLUE exceeded that of GLUE, after which ISPSOGLUE kept improving its performance steadily while GLUE did not. When we compared the 95% uncertainty bounds of the two methods, their general shapes and trends were very similar, but those of ISPSO-GLUE enclosed about 5.4 times more observed values than those of GLUE did. What it means is that ISPSOGLUE requires much less number of parameter samples to generate better performing uncertainty bounds. When compared to ISPSO-GLUE, GLUE overestimated uncertainty in the recession limb following the maximum peak streamflow. For this recession period, GLUE requires to find more behavioral models to reduce the uncertainty. ISPSO-GLUE can be a promising alternative to GLUE because the uncertainty bounds of the method were quantitatively superior to those of GLUE and, especially, computationally expensive hydrologic models are expected to greatly take advantage of the feature.

• Journal of Applied Biological Chemistry
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• v.58 no.3
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• pp.259-265
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• 2015

Momordica charantia, commonly known as bitter melon, has interesting pharmacological activities such as anticancer, antiviral, antibacterial, anti-inflammatory, analgesic, and antioxidant. As supported by recent scientific reports on the beneficial effects of M. charantia, it is one of the most promising functional plants for diabetes today. In this study, we fermented the bitter melon with lactic acid bacteria and investigated the capability of controlling diabetic conditions by decreasing the blood glucose levels. After extracting the fermented bitter melon with hot water or ethanol, we tested several biological activities using mouse models. When we tested the efficacy of the glycemic control, the extracts of fermented bitter melon significantly lowered the blood glucose levels of the alloxan-induced diabetic mice. We also found that the lactic acid bacteria-fermented bitter melon protected liver damages from the treatment of alloxan monohydrates and maintained low levels of triglycerides and high levels of HDL cholesterol in these mouse models. These results suggest that our approach on fermenting bitter melon and the extracts of fermented bitter melon could lead to the possibility of the development of functional foods that contain the effectiveness of controlling blood glucose and lipid levels as well as preventing liver damages.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.137-144
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• 2005

Silica in primary system combines with an alkali grammatical particle metal and forms the zeolite layer which is hindering the heat transfer on the surface of the cladding. Zeolite layer becomes the cause of the damage in this way. The problems of the NPP's primary system have been issued steadily by EPRI. Through a series of experiments of the laboratory scale, we confirmed the applicability of NF membrane for silica removal, as silica rejection rate of NF membrane is about $60\;{\sim}\;70\%$ and boron rejection rate is about $10\;{\sim}\;20\%$. We accomplished a site experiment about four NF membranes manufactured by FilmTec and Osmonics Inc. In experiment using 400L of SFP water, when operation pressure is $10kg_{f}/cm^2$, we confirmed that the silica rejection rate of NF90-2540 manufactured by FilmTec Inc. is about $98\%$, boron rejection rate is about $43\%$. The silica rejection rate of NF270-2540 is about $38\%$, boron rejection rate is about $3.5\%$. Afterward, through additional experiments, such as long term characteristic experiments, we are going to design a optimum NF membrane system for silica removal.

• Journal of Internet Computing and Services
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• v.12 no.1
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• pp.99-110
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• 2011

Mobile environments rapidly changing and digital convergence widely employed, mobile devices including smart phones have been playing a critical role that changes users' lifestyle in the areas of entertainments, businesses and information services. The various services using mobile devices are developing to meet the personal needs of users in the mobile environments. Especially, an LBS (Location-Based Service) is combined with other services and contents such as augmented reality, mobile SNS (Social Network Service), games, and searching, which can provide convenient and useful services to mobile users. In this paper, we design and implement the prototype of mobile personal assistant (PA) agents. Our personal assistant agent helps users do some tasks by hiding the complexity of difficult tasks, performing tasks on behalf of the users, and reflecting the preferences of users. To identify user's preferences and provide personalized services, clustering and classification algorithms of data mining are applied. The clusters of the log data using clustering algorithms are made by measuring the dissimilarity between two objects based on usage patterns. The classification algorithms produce user profiles within each cluster, which make it possible for PA agents to provide users with personalized services and contents. In the experiment, we measured the classification accuracy of user model clustered using clustering algorithms. It turned out that the classification accuracy using our method was increased by 17.42%, compared with that using other clustering algorithms.

• Journal of Life Science
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• v.15 no.3 s.70
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• pp.406-414
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• 2005

The genetic instability of cancer cells may be related to inappropriately activated DNA repair pathways. In present study, the modulated expression of DNA-dependent protein kinase (DNA-PK), a major DNA repair protein, in human cancer metastatic cells was tested. The expressions of Ku70/80, regulatory subunit of DNA-PK, and the Ku DNA-binding activity in various highly metastatic cell lines were higher than those in each parental cell line. Also, the expression of DNA-PKcs, catalytic subunit of DNA-PK, and the kinase activity of the whole DNA-PK complex in highly metastatic cells were significantly increased as compared to those of parental cells, suggesting that the enhanced DNA repair capacity of metastatic cells could be associated with aberrant use of DNA repair, which may mediate tumor progression and metastatic potential. Increased EGFR (epidermal growth factor receptor) signaling has been associated with tumor invasion and metastasis, and the linkage between EGFR-mediated signaling and DNA-PK has been suggested. This study showed that PKI166, the new EGFR tyrosine kinase inhibitor, modulated the expressions of Ku70/80 and DNA-PKcs and also revealed the chemosensitization effect of PKI166 against metastatic cells may be in part due to inhibition of Ku70/80. These results suggest that interference in EGFR signaling by EGFR inhibitor resulted in the impairment of DNA repair activity, and thus DNA-PK could be possible molecular targets for therapy against metastatic cancer cells.