• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.217-228
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• 2003

Co-ordinate growth of the brain and skull is achieved through a series of tissue interactions between the developing brain, the growing bones of the skull and the sutures that unite the bones. Craniosynostosis, the premature fusion of cranial sutures, presumably involves disturbance of these interactions. Bmp2, one of bone morphogenetic proteins (Bmps), is involved in the regulation of the shapes of individual bones and the relative proportions of the skeleton. Mutations in the homeobox gene Msx2, known as a downstream gene of Bmp, cause Boston-type human craniosynostosis. The phenotype of Dlx5 homozygote mutant mouse presents craniofacial abnormalities including a delayed ossification of calvarial bone. These facts suggest important roles of Bmp2, Msx2 and Dlx5 genes in the cranial bone growth and suture morphogenesis. To elucidate the function of these molecules in the early morphogenesis of mouse cranial sutures, we first analyzed by in situ hybridization the expression of Bmp2(E15-18), Msx2 and Dlx5 genes in the developing sagittal suture of calvaria during the embryonic stage. Bmp2 mRNA was intensely expressed in the osteogenic fronts and also at the low level in the periosteum of parietal bones during embryonic stage, Msx2 mRNA was intensely expressed in the sutural mesenchyme and mildly expressed in the dura mater during the embryonic stage. Dlx5 mRNA was intensely expressed osteogenic fronts and parietal bones. To further examine the role of Bmp signaling in cranial suture, we did in vitro experiments in E15.5 mouse calvarial explants. Interestingly, implantation of Bmp2-soaked beads onto the osteogenic fronts after 48 hours organ culture resulted in the increase of the tissue thickness and cell number around Bmp2 beads, compared to BSA control beads. In addition Bmp2 induced etopic expressions of Msx2 and Dlx5 genes. On the other hand, overexpression of FGF2 did not induce the expression of Msx2 and Dlx5. Taken together, these data indicate that Bmp2 signaling molecule has a important role in regulating the cranial bone growth and early morphogenesis of cranial suture. We also suggest that Bmp signaling is involved in all the stages of osteogenesis of cranial bones and the maintenance of cranial suture by regulating Msx2 and Dlx5 genes, and that Msx2 and Dlx5 genes are specific transcription factors of Bmp signaling pathway.

• Information Systems Review
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• v.11 no.1
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• pp.161-179
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• 2009

Nowadays an increasing number of Internet users are running individual websites as Blog or Cyworld. As this type of personal media has a great influence on communication among people, business comes to care about Network Effect, Network Software, and Social Network. For instance, Cyworld created the web service called 'Minihompy' for individual web-logs, and acquired 2.4milion users in 2007. Although many people assumed that the popularity of Minihompy, or Blog would be a passing fad, Cyworld has improved its service, and expanded its Network with various contents. This kind of expansion reflects survival efforts from infinite competitions among ISPs (Internet Service Provider) with focus on enhancing usability to users. However, Cyworld's Network Effect is gradually diminished in these days. Both of low production cost of service vendors and the low searching/conversing costs of users combine to make ISPs hard to keep their market share sustainable. To overcome this lackluster trend, Cyworld has adopted new strategies and try to lock their users in their service. Various efforts to improve the continuance and expansion of Network effect remain unclear and uncertain. If we understand beforehand how a service would improve Network effect, and which service could bring more effect, ISPs can get substantial help in launching their new business strategy. Regardless many diverse ideas to increase their user's duration online ISPs cannot guarantee 'how the new service strategies will end up in profitability. Therefore, this research studies about Network effect of Cyworld's 'Minihompy' using System-Dynamics method which could analyze dynamic relation between users and ISPs. Furthermore, the research aims to predict changes of Network Effect based on the strategy of new service. 'Page View' and 'Duration Time' can be enhanced for the short tenn because they enhance the service functionality. However, these services cannot increase the Network in the long-run. Limitations of this research include that we predict the future merely based on the limited data. We also limit the independent variables over Network Effect only to the following two issues: Increasing the number of users and increasing the Service Functionality. Despite of some limitations, this study perhaps gives some insights to the policy makers or others facing the stiff competition in the network business.

• Radiation Oncology Journal
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• v.12 no.1
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• pp.1-8
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• 1994

When cells are exposed to low doses of a mutagenic or clastogenic agents. they often become less sensitive to the effects of a higher dose administered subsequently. Such adaptive responses were first described in Escherichia coli and mammalian cells to low doses of an alkylating agent. Since most of the studies have been carried out with human lymphocytes, it is urgently necessary to study this effect in different cellular systems. Its relation with inherent cellular radiosensitivity and underlying mechanism also remain to be answered. In this study, adaptive response by 1 cGy of gamma rays was investigated in three human lymphoblastoid cell lines which were derived from ataxia telangiectasia homozygote, ataxia telangiectasia heterozygote, and normal individual. Experiments were carried out by delivering 1 cGy followed by 50 cGy of gamma radiation and chromatid breaks were scored as an endpoint. The results indicate that prior exposure to 1 cGy of gamma rays reduces the number of chromatid breaks induced by subsequent higher dose (50 cGy), The expression of this adaptive response was similar among three cell lines despite of their different radiosensitivity. When 3-aminobenzamide, an inhibitor of poly (ADP-ribose) polymerase, was added after 50 cGy, adaptive responses were abolished in all the tested cell lines. Therefore it is suggested that the adaptive response can be observed in human lymphoblastoid cell lines, which was first documented through this study. The expression of adaptive response was similar among the cell lines regardless of their radiosensitivity. The elimination of the adaptive response by 3-aminobenzamide is consistent with the proposal that this adaptive response is the result of the induction of a certain chromosomal repair mechanism.

• Horticultural Science & Technology
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• v.18 no.3
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• pp.342-347
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• 2000

The objectives of this study were to investigate the genetic and phenotypic features of male sterile transformants by pollen-specific expression of diphtheria toxin gene and to find out inheritance patterns of transgene to the next generation. When backcrossed (BC) progenies were tested for expression of kanamycin resistance ($Km^R$), 9 lines out of 13 lines, except 4 lines ($BC_{1}5-13,\;BC_{1}5-23,\;BC_{1}5-28,\;BC_{1}5-32$), showed the ratio of $Km^R$ to kanamycin sensitive ($Km^S$), from 1:30 to all $Km^S$. As a result, they were much lower than Mendelian segregation of a dominant gene. To determine whether male sterility is a heritable and stable trait, 5 male sterile plants ($BC_{1}5-13,\;BC_{1}5-14,\;BC_{1}5-23,\;BC_{1}5-32,\;BC_{1}5-33$ lines) which had different transgene copy numbers were backcrossed as female parents with pollens from wild type. To confirm the existence of the DTx-A gene in the genome of the progenies, PCR was conducted using specific primers of the DTx-A coding region. A PCR band of 428 bp was obtained from each generation, which is the predicted size of the DTx-A gene fragment. Trangenes were inherited to the next $BC_4T_0$ progenies and showed male sterility, however, based on the copy numbers of DTx-A gene male sterile plants did not show predicted ratio. When male sterile plants were backcrossed with fertile plants, fruit capsule sizes and seed settings were relatively reduced from those of selfing wild type plants. The fruit sizes and seed settings were reduced in proportion to the increase in the copy number of DTx-A gene.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.1
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• pp.38-48
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• 2004

Tropospheric ozone data in Korea for 1998-2002 were analyzed to assess the impact on vegetation. SUM06(sum of hourly concentrations at or above 0.06 ppm) and AOT40(accumulated exposure over a threshold of 40 ppb), widely used as ozone indices in the U.S. and Europe, were calculated based on hourly ozone concentration in 612 areas during 1998-2002 in Korea. SUM06 of the highest 30 areas were 5-12 ppm/hr which were almost the same levels of the U.S. average, and a crop loss of 5% would be expected. Ozone pollution in Seoul during 1998-2002 had decreased compared to that for 1990-97 except in the Northern area; however, ozone pollution in Kyunggi during 1998-2002 had been increased twice compare to the previous 5 years. Korea was divided into four regions: Seoul Metropolitan area, Jungbu, Honam, and Youngnam. Ozone pollution in the Seoul Metropolitan area was much higher during 1998-2000 than the other areas, but ozone pollution during 2001-2002 was almost the same in all four regions. Chunnam-Kwangyang na Kyungbuk-Gumi, famous industrial complexes in southern Korea, were significant ozone pollution areas. However, other industrial complexes, such as Incheon, Ulsan, and Kyunggi-Sihwa, were not polluted compared to their neighbors. Comparing all ozone indices, SUM06(yr), SUM06(3mon), AOT40(yr), AOT40(3mon), number of hours exceeding 100 ppb, 95 percentile, 99 percentile, and maximum concentration, it was determined reasonable to use SUM06(3mon), AOT40(3mon) and number of hours exceeding 100 ppb for evaluation of the chronic impact of ozone on vegetation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.4
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• pp.176-184
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• 2011

Cold air on sloping surfaces flows down to the valley bottom in mountainous terrain at calm and clear nights. Based on the assumption that the cold air flow may be the same as the water flow, current models estimate temperature drop by regarding the cold air accumulation at a given location as the water-like free drainage. At a closed catchment whose outlet is blocked by man-made obstacles such as banks and roads, however, the water-like free drainage assumption is no longer valid because the cold air accumulates from the bottom first. We developed an empirical model to estimate quantitatively the effect of cold pool on nocturnal temperature in a closed catchment. In our model, a closed catchment is treated like a "vessel", and a digital elevation model (DEM) was used to calculate the maximum capacity of the cold pool formed in a closed catchment. We introduce a topographical variable named "shape factor", which is the ratio of the cold air accumulation potential across the whole catchment area to the maximum capacity of the cold pool to describe the relative size of temperature drop at a wider range of catchment shapes. The shape factor is then used to simulate the density profile of cold pool formed in a given catchment based on a hypsometric equation. The cold lake module was incorporated with the existing model (i.e., Chung et al., 2006), generating a new model and predicting distribution of minimum temperature over closed catchments. We applied this model to Akyang valley (i.e., a typical closed catchment of 53 $km^2$ area) in the southern skirt of Mt. Jiri National Park where 12 automated weather stations (AWS) are operational. The performance of the model was evaluated based on the feasibility of delineating the temperature pattern accurately at cold pool forming at night. Overall, the model's ability of simulating the spatial pattern of lower temperature were improved especially at the valley bottom, showing a similar pattern of the estimated temperature with that of thermal images obtained across the valley at dawn (0520 to 0600 local standard time) of 17 May 2011. Error in temperature estimation, calculated with the root mean square error using the 10 low-lying AWSs, was substantially decreased from $1.30^{\circ}C$ with the existing model to $0.71^{\circ}C$ with the new model. These results suggest the feasibility of the new method in predicting the site-specific freeze and frost warning at a closed catchment.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.919-932
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• 2019

Fine particulate matter (PM2.5) is not only affected by anthropogenic emissions, but also intensifies, migrates, decreases by hydrometeorological factors. Therefore, it is essential to understand relationships between the hydrometeorological factors and PM2.5 concentration. In Korea, PM2.5 concentration is measured at the ground observatories and estimated data are given to locations where observatories are not present. In this way, the data is not suitable to represent an area, hence it is impossible to know accurate concentration at such locations. In addition, it is hard to trace migration, intensification, reduction of PM2.5. In this study, we analyzed the relationships between hydrometeorological factors, acquired from Global Land Data Assimilation System (GLDAS), and PM2.5 by means of Bayesian Model Averaging (BMA). By BMA, we also selected factors that have meaningful relationship with the variation of PM2.5 concentration. 4 PM2.5 concentration models for different seasons were developed using those selected factors, with Aerosol Optical Depth (AOD) from MODerate resolution Imaging Spectroradiometer (MODIS). Finally, we mapped the result of the model, to show spatial distribution of PM2.5. The model correlated well with the observed PM2.5 concentration (R ~0.7; IOA ~0.78; RMSE ~7.66 ㎍/㎥). When the models were compared with the observed PM2.5 concentrations at different locations, the correlation coefficients differed (R: 0.32-0.82), although there were similarities in data distribution. The developed concentration map using the models showed its capability in representing temporal, spatial variation of PM2.5 concentration. The result of this study is expected to be able to facilitate researches that aim to analyze sources and movements of PM2.5, if the study area is extended to East Asia.

• Applied Microscopy
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• v.35 no.3
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• pp.165-176
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• 2005

Studies on molecular plasticity of Bermann glia (BG) after harmaline-induced Purkinje cell (PC) degeneration in the rat cerebellum. The intimate structural relationship between BG and PC, evidenced by the sheathing of the PC dendrites by veil-like process from the BG has been suggestive of the close functional relationship between these two cell types. However, little is known about metabolic couplings between these cells. This study designed to investigate molecular plasticity of BG in the rat cerebellum in which PCs were chemically ablated by harmaline treatment. Immunohistochemical examination reveals that harmaline induced PC degeneration causes a marked glial reaction in the cerebellum with activated BG and microglia aligned in parasagittal stripes within the vermis. In these strips, activated BG were associated with upregulaion of metallotheionein, while GLAST and was down regulated, as compared with nearby intact area where both BG are in contact with PCs. The data from this study demonstrate that BG can change their phenotypic expression when BG loose their contact with PCs. It is conceivable that activated BG may upregulate structural proteins, metallothionein expression to use for their proliferation and hypertrophy; metallothionein expression to cope with oxidative stress induced by PC degeneration and microglial activation. On the contrary, BG may down regulated expression of GLAST because sustained loss of contact with PCs would eliminate the necessity for the cellular machinery involved glutamate metabolism. In conclusion, BG might respond man to death of PCs by undergoing a change in metabolic state. It seems possible that signaling molecules released from PCs regulates the phenotype expression of BG. Also ultrastructures in the organelles of normal PC and BG are distinguished by mitochondrial appearance, and distributed vesicles at the synaptic area in the cytoplasm.

• Korean Journal of Head & Neck Oncology
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• v.15 no.2
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• pp.149-155
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• 1999

Objectives: To study the clinical features of the primary nasal/nasopharyngeal non-Hodgkin's lymphomas and to evaluate the implication of immunophenotyping as a prognostic factor. Patients and Methods: From January 1990 to December 1997,41 patients(median age, 41 years) of primary nasal/nasopharyngeal non-Hodgkin's lymphoma were studied. The clinical records and paraffin-embedded tissue blocks were reviewed retrospectively. The histologic features, immunophenotypic findings(pan-T, pan-B, CD3, CD56) and Epstein-Barr virus in situ hybridizatios were examined. The prognostic factors for clinical outcome were evaluated in these patients. According to Ann-Arbor system, there were 30 patiets(73%) with stage IE, 4(10%) with stage IIE, 3(7%) with stage IIIE, 4(10%) with stage IVE lymphoma. Among the patients with stage IE/IIE, 4 patients received local radiation alone, 4 received chemotherapy alone, 25 received combination chemotherapy and radiotherapy and 1 refused treatment. The patients with stage IIIE/IVE were given combination chemotherapy and radiotherapy. Results: Immunophenotyping were performed in 40 patients and staining results were as follows: 3(7%) patients with B cell, 17(42%) with T cell, 18(44%) with NK/T cell(CD56 positive), and two patients with unclassifiable result. Epstein-Barr(EB) virus in situ hybridization were performed in 28 patients and 23(82%) patients had positive EBV-encoded RNAs(EBERs). 21(55%) patients achieved a complete remission. There was no difference in complete remission between radiation alone and combination therapy. With median follow-up of 30 months, 5-years disease free survival of complete responders was 60% and 5-years overall survival rate was 36%. Multivariate analysis showed that better overall survival was related with absence of B symptoms, ECOG performance${\leq}1$ and non-NK cells. Conclusion: Most of all cases were positive for EBER. Since NK/T phenotype carried the worst prognosis, analysis for CD56 expression should be done. Further prospective studies were warranted to evaluate the role of chemotherapy in stage IE/IIE.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.198-203
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• 2007

DNA transfection is a powerful tool for studying gene functions. The $Ca^{2+}$-phosphate precipitation remains one of the most popular and cost-effective transfection techniques. Mature neurons are more resistant to transfection than young ones and most other cell types, and easy to die if microenvironment changes. Here, we report a transfection protocol for mature neurons. The critical modifications are inclusion of glial cells in culture and careful control of $Ca^{2+}$-phosphate precipitation under microscope. Cerebral glial cells were grown until ${\sim}70-80%$ confluence in DMEM/10% horse serum, which was thereafter replaced with serum-free Neurobasal/Ara-C, and 319 hippocampal neurons were plated onto the glial layer Formation of fine $DNA/Ca^{2+}$-phosphate precipitates was induced using Clontech $CalPhos^{TM}$ Mammalian Transfection Kit, and the size ($0.5-1\;{\mu}m$ in diameter) and density(about 10 particles/$100\;{\mu}m^2$) were carefully controlled by the time of incubation in the medium. This modified protocol can be reliably applied for transfection of mature neurons that are maintained longer than two weeks in vitro, resulting in 10-15 healthy transfected neurons per a well of 24-well plates. The efficacy of the protocol was verified by punctate expression of $pEGFP-CaMKII{\alpha}$, a synaptic protein, and diffuse expression of pDsRed2. Our protocol provides a reliable method for transfection of mature neurons in vitro.