• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.3
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• pp.251-260
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• 2003

A three dimensional (3-D) method of analysis is presented for determining the free vibration frequencies and mode shapes of deep, tapered rods and beams with circular cross section. Unlike conventional rod and beam theories, which are mathematically one-dimensional (1-D), the present method is based upon the 3-D dynamic equations of elasticity. Displacement components u/sup r/, u/sub θ/ and u/sub z/, in the radial, circumferential, and axial directions, respectively, are taken to be sinusoidal in time, periodic in , and algebraic polynomials in the r and z directions. Potential (strain) and kinetic energies of the rods and beams are formulated, the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four-digit exactitude is demonstrated for the first five frequencies of the rods and beams. Novel numerical results are tabulated for nine different tapered rods and beams with linear, quadratic, and cubic variations of radial thickness in the axial direction using the 3D theory. Comparisons are also made with results for linearly tapered beams from 1-D classical Euler-Bernoulli beam theory.

• Economic and Environmental Geology
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• v.41 no.3
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• pp.287-297
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• 2008

In order to estimate the preliminary development feasibility according to the commodity, the content of 8 strategic metallic commoditites(Pb, Zn, Cu, Fe, Mo, W, Au, U) in 68 ore specimens obtained from 34 metallic mines within the Taebaegsan-Hwanggangri mineralized zone were analyzed. Analytical results are as follows. The ore specimen of Sangdong mine contained 23% copper(cut-off grade=0.7%) and those of Cheongil and Samhwanghak mines contained average 5% zinc(cut-off grade=2.0%). Especially, the detailed investigation on the above-mentioned mines is required. And, in case of molybdenum(cut-off grade=0.02%) content in Yeonhwa No. 2(0.04%) and Hong-cheon mine(0.02%), and lead(cut-off grade=0.58%) content in Wongasa mine(0.70%), and gold(cut-off grade=10ppm) content in Dongmyoung(279ppm) and Samhwanghak mine(251ppm), it is required to elastically carry out the revaluation on reopening of mines in terms of the international metal price. On the other hand, in case of uranium, iron and tungsten, it is thought that there are no mines with the development potential value in this study.

• Journal of Science Education
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• v.47 no.3
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• pp.251-262
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• 2023

In this study, we examine other factors that may contribute to the decline in students' academic performance and educational attainment. Many media reports, as well as previous studies, have suggested that virtual learning is the main reason for the decline in students' academic performance. However, the 2020 National Student Achievement Survey, which was conducted in conjunction with the COVID-19 Distance Learning Environment Student Survey, showed that students were highly satisfied with distance learning (70-80%), and the analysis of the National Assessment of Educational Achievement showed that students' academic performance had already been declining year by year since 2017, with a general downward curve. For further confirmation, we analyzed the performance of high school students on mock exams and found that their performance was not normally distributed, but rather a right-skewed U-shaped distribution with a shrinking number of medians and severe polarization. We found that this phenomenon is not simply because of the mode or quality of the virtual classroom, but to a variety of factors, including environmental influences such as care and management at home, changes in investment in private education, increased time spent on online devices while taking virtual classes at the bottom, and increased time spent watching online content, games, and videos that are not related to learning.

• The Journal of Korean Philosophical History
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• no.25
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• pp.251-292
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• 2009

In this thesis, the status of Pre-Chin Study of One Hundred Schools in the history of Korean thoughts, and in addition, the reception of $Hs{\ddot{u}}n$ Tzu's ideology and the aspect of its development in Korea were examined. Moreover, the different understandings of $Hs{\ddot{u}}n$ Tzu and their trend of the times were summarized through the intellectuals' collection of works from the end of Goryeo Dynasty and the beginning of Cho Sun Dynasty to 18-19 century. What was revealed through the study can be summed up as the followings. From the age of Three States to the middle part of Goryeo Dynasty, few intellectuals regarded other schools or philosophers among Study of One Hundred Schools as heresies and blamed them. However, since Mencius had been established as the legitimate classical scripture of Confucianism after the end of Goryeo Dynasty and the beginning of Cho Sun Dynasty, other Pre-Chin philosophers including $Hs{\ddot{u}}n$ Tzu had started to be regarded and criticized as heresies. Intellectuals of Goryeo Dynasty and the early Cho Sun Dynasty made various estimates on $Hs{\ddot{u}}n$ Tzu's doctrine of the evilness of human nature, but we can see the understanding of $Hs{\ddot{u}}n$ Tzu became deeper. In the heyday of Neo-Confucianism in Cho Sun Dynasty, the intensity of the criticism on $Hs{\ddot{u}}n$ Tzu by intellectuals rather tended to decrease, compared to that of the early Cho Sun Dynasty, which produced contrary evidence that the world view of Sung Confucianism, based on Mencius' doctrine of the goodness of human nature, had been already established. Also, even the intellectuals criticizing the evilness of human nature positively quoted $Hs{\ddot{u}}n$ Tzu's other ideas in general. In 17th century, there were some arguments to conclude $Hs{\ddot{u}}n$ Tzu as Legalism, but the general trend came to accept Study of One Hundred Schools constructively, challenging the authority of Sung Confucianism, or based on positive school. In 18th century, it can be confirmed that the understanding on $Hs{\ddot{u}}n$ Tzu became broader, and particularly in the historical research of letters, $Hs{\ddot{u}}n$ Tzu's original texts and annotations were used in many ways. In short, the intellectuals' criticism on $Hs{\ddot{u}}n$ Tzu in Cho Sun Dynasty was always grounded on his argument of the evilness of human nature, and furthermore, on connecting it to Legalism, related to the Fenshukengru. On the other hand, it can be said that they generally accepted other ideas of $Hs{\ddot{u}}n$ Tzu positively, except for the idea of the evilness of human nature. However, it's worth paying attention to the fact that those intellectuals who criticized $Hs{\ddot{u}}n$ Tzu could easily meet with the books of Study of One Hundred Schools, and relatively had an open attitude in terms of knowledge.

• BMB Reports
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• v.45 no.8
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• pp.470-475
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• 2012

Protein arginine methyltransferase 1 (PRMT1), a type-I arginine methyltransferase, has been implicated in diverse cellular events. We have focused on the role of PRMT1 in gliomagenesis. In this study, we showed that PRMT1 expression was up-regulated in glioma tissues and cell lines compared with normal brain tissues. The knock-down of PRMT1 resulted in an arrest in the G1-S phase of the cell cycle, proliferation inhibition and apoptosis induction in four glioma cell lines (T98G, U87MG, U251, and A172). Moreover, an in vivo study confirmed that the tumor growth in nude mouse xenografts was significantly decreased in the RNAi-PRMT1 group. Additionally, we found that the level of the asymmetric dimethylated modification of H4R3, a substrate of PRMT1, was higher in glioma cells than in normal brain tissues and decreased after PRMT1 knock-down. Our data suggest a potential role for PRMT1 as a novel biomarker of and therapeutic target in gliomas.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.3
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• pp.203-212
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• 2020

Promyelocytic leukemia (PML) gene, through alternative splicing of its C-terminal region, generates several PML isoforms that interact with specific partners and perform distinct functions. The PML protein is a tumor suppressor that plays an important role by interacting with various proteins. Herein, we investigated the effect of the PML isoforms on oncostatin M (OSM)-induced signal transducer and activator of transcription-3 (STAT-3) transcriptional activity. PML influenced OSM-induced STAT-3 activity in a cell type-specific manner, which was dependent on the p53 status of the cells but regardless of PML isoform. Interestingly, overexpression of PML exerted opposite effects on OSM-induced STAT-3 activity in p53 wild-type and mutant cells. Specifically, overexpression of PML in the cell lines bearing wild-type p53 (NIH3T3 and U87-MG cells) decreased OSM-induced STAT-3 transcriptional activity, whereas overexpression of PML increased OSM-induced STAT-3 transcriptional activity in mutant p53-bearing cell lines (HEK293T and U251-MG cells). When wild-type p53 cells were co-transfected with PML-IV and R273H-p53 mutant, OSM-mediated STAT-3 transcriptional activity was significantly enhanced, compared to that of cells which were transfected with PML-IV alone; however, when cells bearing mutant p53 were co-transfected with PML-IV and wild-type p53, OSM-induced STAT-3 transcriptional activity was significantly decreased, compared to that of transfected cells with PML-IV alone. In conclusion, PML acts together with wild-type or mutant p53 and influences OSM-mediated STAT-3 activity in a negative or positive manner, resulting in the aberrant activation of STAT-3 in cancer cells bearing mutant p53 probably might occur through the interaction of mutant p53 with PML.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.2
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• pp.769-773
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• 2015

Fibulin-5 has recently been considered as a potential tumor suppressor in human cancers. Several studies have shown that it is down-regulated in a variety of tumor types and inhibits tumor growth and metastasis. This study was aimed to investigate the clinical significance of fibulin-5 in glioma and its role in cell proliferation and invasion. We found that the expression of fibulin-5 in glioma tissues was significantly lower than those in normal brain (NB) tissues. Negative expression was significantly correlated with advanced clinical stage (grade III+IV). Furthermore, Fibulin-5 negative expression was correlated with a shorter overall survival of glioma patients. Multivariate Cox repression analysis indicated that fibulin-5 was an independent factor for predicting overall survival of glioma patients. Overexpression obviously inhibited cell proliferation in U251 and U87 cells. Furthermore, it significantly reduced the number of migrating and invading glioma cells. In conclusion, impaired expression of fibulin-5 is correlated with the advanced tumor stage in glioma. Otherwise, Fibulin-5 is an independent prognostic marker for predicting overall survival of glioma patients. Mechanistically, it may function as a tumor suppressor via inhibiting cell proliferation and invasion in gliomas.

• Microbiology and Biotechnology Letters
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• v.18 no.3
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• pp.251-259
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• 1990

Asp. usumii IAM 2185 was selected as a strain producing the powerful raw starch digesting glucoamylase. The optimum initial pH, the optimum temperature and the optimum cultural time for the enzyme production on wheat bran medium were pH 6-8,25-$30^{\circ}C$ and 72 hrs, respectively. The addition of ammonium nitrate and albumin on wheat bran medium, respectively, increase slightly the enzyme production. The enzyme was purified by ammonium sulfate fractionation, CM-cellulose and DEAE-cellulose column chromatography. The specific activity of the purified enzyme was 34.3 U/mg protein and the yield of enzyme activity was 10.3%. The purified enzyme showed a single band on polyacrylamide disc gel electrophoresis and its molecular weight was estimated to be 67,000 by SDS polyacrylamide disc gel electrophoresis. The isoelectric point for the purified enzyme was pR 3.7. The optimum temperature and optimum pH were $60^{\circ}C$and pH 3.0 and the purified enzyme was stable in the pH range of 1.0-11.0. The purified enzyme was stable below $50^{\circ}C$ and its thermostability was greatly increased by the addition of $Ca^{2+}$. The purified enzyme showed a high hydrolysis rate on various raw starches such as corn, rice, yam, arrow root, sweet potato and glutinous rice.

• Journal of Korean society of Dental Hygiene
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• v.8 no.4
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• pp.251-263
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• 2008

Purpose : The purpose of this study was to examine the stressors and coping patterns of dental hygiene students in a bid to boost the efficiency of guidance and counseling. Subjects and Method : The subjects in this study were 359 dental hygiene students from some colleges. After a survey was conducted, the collected data were analyzed with SPSS 13.0 program. Statistical data on frequency and percentage were obtained, and ANOVA and t-test were utilized. Findings : 1. The dental hygiene students investigated suffered the most stress with excessive workload, and anxiety about the national examination was the greatest stressor. Among the areas of stressors, school life put the most pressure on them(3.25). 2. The most dominant way for the dental hygiene students to handle stress was talking with friends(4.32). Out of the areas of stress-coping patterns, mental coping was most prevalent(2.94), and the least common stress-coping area was physical coping(2.23). 3. As for the relationship between the place where they were raised and stress-coping styles, physical coping and direct coping were more widespread among the students who were brought up in large urban communities than the others. Conclusion : As the dental hygiene students were different in stress-coping styles according to the place where they were grown, educators who nurture dental hygienists should offer customized education and counseling in consideration of where students were brought up.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.4
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• pp.243-251
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• 2006

Dideoxypetrosynol A, a polyacetylene from the marine sponge Petrosia sp., is known to exhibit significant selective cytotoxic activity against a small panel of human tumor cell lines, however, the mechanisms of which are poorly understood. In the present study, it was investigated the further possible mechanisms by which dideoxytetrosynol A exerts its anti-proliferative action in cultured human leukemia cell line U937. We observed that the proliferation-inhibitory effect of dideoxypetrosynol A was due to the induction of G1 arrest of the cell cycle and apoptosis, which effects were associated with up-regulation of cyclin D1 and down-regulation of cyclin E without any change in cyclin-dependent-kinases (Cdks) expression. Dideoxypetrosynol A markedly induced the levels of Cdk inhibitor p16/INK4a expression. Furthermore, down-regulation of phosphorylation of retinoblastoma protein (pRB) by this compound was associated with enhanced binding of pRB and the transcription factor E2F-1. The increase in apoptosis was associated with a dose-dependent up-regulation in pro-apoptotic Bax expression and activation of caspase-3 and caspase-9. Dideoxytetrosynol A decreased the levels of cyclooxygenase (COX)-2 mRNA and protein expression without significant changes in the levels of COX-1, which was correlated with a decrease in prostaglandin E2 (PGE2) synthesis. Furthermore, dideoxytetrosynol A treatment markedly inhibited the activity of telomerase, and the expression of human telomerase reverse transcriptase (hTERT), a main determinant of the telomerase enzymatic activity, was progressively down-regulated by dideoxytetrosynol A treatment in a dose-dependent fashion. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of dideoxytetrosynol A.