• Journal of Ginseng Research
• /
• v.3 no.1
• /
• pp.35-39
• /
• 1979

Present studies were carried out to clarify the variation of flowering date in the variants of Korean ginseng Plants. In general, the variation of flowering date of violet-stem variant was found to be mere variable as compared with that of yellow-berry variant. And flowers began to bloom earlier in yellow-berry variant than in violet-stem variant. In violet-stem variant as well as in yellow-berry variant, the flowering date of 5-year old plants was earlier than that of 3- and 4-year old plants. As for the flowering date according to the different lines, the third line was earlier than the first or the fifth line.

• Journal of Information Science Theory and Practice
• /
• v.2 no.1
• /
• pp.35-47
• /
• 2014

Korean researchers' scientific outputs are increasing rapidly with the growth of both Korea's economy and industry size. This is the time to analyze the scientific output (STEM area) of Korea over the last 40 years. For this analysis, this study used the SCIE database of Web of Science (WoS), which is a representative global Citation Index Service. The objects of analysis are every Korean document published in the SCIE journal, and the research scopes are (1) analysis of citation and subject categories and (2) analysis of co-authorship. Through this study, characteristics such as cited trend and research trend by subject, and the status of collaboration between Korea and other countries including the 50 states of the USA were revealed.

• The korean journal of orthodontics
• /
• v.42 no.6
• /
• pp.307-317
• /
• 2012

Objective: The purpose of this study was to investigate the isolation and characterization of multipotent human periodontal ligament (PDL) stem cells and to assess their ability to differentiate into bone, cartilage, and adipose tissue. Methods: PDL stem cells were isolated from 7 extracted human premolar teeth. Human PDL cells were expanded in culture, stained using anti-CD29, -CD34, -CD44, and -STRO-1 antibodies, and sorted by fluorescent activated cell sorting (FACS). Gingival fibroblasts (GFs) served as a positive control. PDL stem cells and GFs were cultured using standard conditions conducive for osteogenic, chondrogenic, or adipogenic differentiation. Results: An average of $152.8{\pm}27.6$ colony-forming units was present at day 7 in cultures of PDL stem cells. At day 4, PDL stem cells exhibited a significant increase in proliferation (p < 0.05), reaching nearly double the proliferation rate of GFs. About $5.6{\pm}4.5%$ of cells in human PDL tissues were strongly STRO-1-positive. In osteogenic cultures, calcium nodules were observed by day 21 in PDL stem cells, which showed more intense calcium staining than GF cultures. In adipogenic cultures, both cell populations showed positive Oil Red O staining by day 21. Additionally, in chondrogenic cultures, PDL stem cells expressed collagen type II by day 21. Conclusions: The PDL contains multipotent stem cells that have the potential to differentiate into osteoblasts, chondrocytes, and adipocytes. This adult PDL stem cell population can be utilized as potential sources of PDL in tissue engineering applications.

• Journal of Science Education
• /
• v.33 no.2
• /
• pp.207-219
• /
• 2009

This study aims to investigate the key common topics identified and discussed in relevant literature associated with the integrative efforts among STEM disciplines. The key methodology and pedagogy were examined and the significant benefits of using the design method for STEM education were discussed. Meta-analysis was employed and qualitative approach was mainly used to synthesize the major findings and conclusions of the 33 empirical studies. The findings of this meta-analysis revealed that the types and names describing the design methods used the various terms, but the key features have reflected the similar pedagogical benefits and key characteristics. The engineering design is an effective strategic methodology and pedagogy for STEM education. In addition, the design methods show the key benefits including (1) to improve academic achievement, (2) to promote students' affective gains, (3) to facilitate collaborative learning, and (4) to explore STEM related careers and jobs. The collaborative works among STEM professions are needed to promote the benefits of using design methods for integrating STEM subjects.

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.6
• /
• pp.81-89
• /
• 2010

The purpose of this research is to verify the influence of STEM integrate education using educational robots on improvement of the level of attitude towards Mathematics. The following hypothesis was formulated in order to achieve this purpose: There will be a meaningful difference in the level of attitude towards Mathematics between elementary school students educated by STEM integrated education with robots and by the traditional method of teaching Mathematics. To prove this hypothesis, 56 of first grade students were tested under the nonequivalent control group in the pretest-posttest designs. As a result of the study, it is showed that STEM integrated education has a positive effect on promoting the level of elementary school students' attitude towards Mathematics. Therefore, we need the instructional activities which can combine the knowledge gained from a variety of curriculum with activities by using educational robots.

• International Journal of Stem Cells
• /
• v.7 no.2
• /
• pp.108-117
• /
• 2014

Background and Objectives: Genomic imprinting is an inheritance phenomenon by which a subset of genes are expressed from one allele of two homologous chromosomes in a parent of origin-specific manner. Even though fine-tuned regulation of genomic imprinting process is essential for normal development, no other means are available to study genomic imprinting in human during embryonic development. In relation with this bottleneck, differentiation of human embryonic stem cells (hESCs) into specialized lineages may be considered as an alternative to mimic human development. Methods and Results: In this study, hESCs were differentiated into three lineage cell types to analyze temporal and spatial expression of imprinted genes. Of 19 imprinted genes examined, 15 imprinted genes showed similar transcriptional level among two hESC lines and two human induced pluripotent stem cell (hiPSC) lines. Expressional patterns of most imprinted genes were varied in progenitors and fully differentiated cells which were derived from hESCs. Also, no consistence was observed in the expression pattern of imprinted genes within an imprinting domain during in vitro differentiation of hESCs into three lineage cell types. Conclusions: Transcriptional expression of imprinted genes is regulated in a cell type- specific manner in hESCs during in vitro differentiation.

• BMB Reports
• /
• v.36 no.1
• /
• pp.43-48
• /
• 2003

Understanding the process of carcinogenesis will involve both the accumulation of many scientific facts derived from molecular, biochemical, cellular, physiological, whole animal experiments and epidemiological studies, as well as from conceptual understanding as to how to order and integrate those facts. From decades of cancer research, a number of the "hallmarks of cancer" have been identified, as well as their attendant concepts, including oncogenes, tumor suppressor genes, cell cycle biochemistry, hypotheses of metastasis, angiogenesis, etc. While all these "hallmarks" are well known, two important concepts, with their associated scientific observations, have been generally ignored by many in the cancer research field. The objective of the short review is to highlight the concept of the role of human adult pluri-potent stem cells as "target cells" for the carcinogenic process and the concept of the role of gap junctional intercellular communication in the multi-stage, multi-mechanism process of carcinogenesis. With these two concepts, an attempt has been made to integrate the other well-known concepts, such as the multi-stage, multi-mechanisn or the "initiation/promotion/progression" hypothesis; the stem cell theory of carcinogenesis; the oncogene/tumor suppression theory and the mutation/epigenetic theories of carcinogenesis. This new "integrative" theory tries to explain the well-known "hallmarks" of cancers, including the observation that cancer cells lack either heterologous or homologous gap junctional intercellular communication whereas normal human adult stem cells do not have expressed or functional gap junctional intercellular communication. On the other hand, their normal differentiated, non-stem cell derivatives do express connexins and express gap junctional intercellular communication during their differentiation. Examination of the roles of chemical tumor promoters, oncogenes, connexin knock-out mice and roles of genetically-engineered tumor and normal cells with connexin and anti-sense connexin genes, respectively, seems to provide evidence which is consistent with the roles of both stem cells and gap junctional communication playing a major role in carcinogenesis. The integrative hypothesis provides new strategies for chemoprevention and chemotherapy which focuses on modulating connexin gene expression or gap junctional intercellular communication in the premalignant and malignant cells, respectively.

• Development and Reproduction
• /
• v.14 no.2
• /
• pp.43-50
• /
• 2010

Recently induced pluripotent stem (iPS) cells are derived from somatic cells by ectopic expression of several transcription factors (reprogramming factors) using technology of somatic cell reprogramming. iPS cells are able to selfrenew and differentiate into all type of cells in the body similarly to embryonic stem cells. Because iPS cells have advantages that can avoid immune rejection after transplantation and ethical issues unlike embryonic stem cells, research on iPS has made significant progress since the first report by Yamanaka in 2006. Nevertheless of many advantages of iPS, safer methods to introduce reprogramming factors into somatic cells must be developed due to safety concerns regarding viral vectors, and safer reprogramming factors to substitute the oncogenes should be evaluated for clinical application of iPS. Here we discuss the recent progress in reprogramming factors in embryonic stem cells, oocytes, and embryos, and discuss further research for finding new, more reliable and safer reprogramming factors.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.7
• /
• pp.809-815
• /
• 2016

In this paper, the electrical values of resistance, current, and voltage condition of reactivity is analyzed by applying the direct current (DC) voltage in medium for stem cell regeneration treatment. The voltage response by medium is related to electrical stimulation in the process of induction of differentiation for stem cell and the differentiation condition can be checked depending on the response of voltage condition. If the voltage level is lower in reacting response of a medium, the stem cell stimulation condition is stable, and if the voltage changing level is higher, the stem cell stimulation condition is unstable and a considerable loss will be resulted in the differentiation process. In this research, the optimization of electrical stimulation condition is expected for possible stem cell regeneration treatment.

• Journal of Korean Society of Forest Science
• /
• v.96 no.1
• /
• pp.40-47
• /
• 2007

The objectives of this study were to derive site index and stem volume prediction equation based on stem analysis data for Larix leptolepis in Jinan region. The function for site index was developed by algebraic difference equation method. Polymorphic site index family curves with base age of 40 were presented based on the Schumacher height equation. The best stem volume prediction equation was suggested as $V=0.00260+0.00000399D^2H$. The simultaneous F-test using this equation showed that the estimated tree stem volumes were not significantly different (${\alpha}=0.05$ level) from the observed stem volumes for model evaluation. Therefore, site index and volume prediction equations prepared in this study could provide an indication of site quality and basic information for making of yield table, and could be used for rational forest management of Larix leptolepis stands grown in Jinan region.