• Journal of Korean Society of Forest Science
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• v.89 no.4
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• pp.488-496
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• 2000

This study was carried out to investigate the characteristics of longitudinal permeability and hydraulic resistance, and to compare the longitudinal permeability ($K_E$) calculated by the Hagen-Poiseuille's law (Siau, 1971) and the longitudinal permeability (K) measured in sapwood of Acer mono stem. The volume flow rate (Q) in a vessel was $0.80{\times}10^{-4}cm^3/sec$ and the hydraulic resistance ($R_S$) to viscous flow through a vessel was, on average, $1.37{\times}10^{10}dyn{\cdot}sec{\cdot}cm^{-3}{\cdot}cm^{-2}$. The average value of volume flow rate ($Q_N$) through the cross section of sapwood was $0.32cm^3{\cdot}sec^{-1}{\cdot}cm^{-2}$, and the average resistance ($R_{SN}$) was $3.59{\times}10^6dyn{\cdot}sec{\cdot}cm^{-3}{\cdot}cm^{-2}$. The values of K decreased as the diameter of stem increases, which was attributable to variations in the number of vessel per unit area rather than in vessel diameter, and to different resistances in the conducting tissues of each part of the stem. The average value of K measured at breast height was 31% of average value of $K_E$. The $K/K_E$ ratios were 100% in 4 to 6 year-old stems and more than 90% in 7 to 27 year-old stems. The $K/K_E$ ratio decreased as the age of stems increases, and was not more than 20% in near-ground parts of stem.

• Tribology and Lubricants
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• v.31 no.5
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• pp.213-220
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• 2015

This study evaluates the effect of grooves on the stem part of a plunger on the lubrication characteristics of a fuel injection pump (FIP) by using hydrodynamic lubrication analysis. The current study uses the two-dimensional Reynolds equation to evaluate the changes in lubrication characteristics with variations in clearance, viscosity, and grooves for a laminar, incompressible, and unsteady state flow. This study investigates the lubrication characteristics by comparing the dimensionless minimum film thickness or the film parameter, which is the ratio of the minimum film thickness to surface roughness. The analysis method for the groove section differs depending on the depth of the groove. For instance, in the case of a shallow groove, the film thickness equation considers the depth of the groove, while in the case of a deep grove, it considers the flow continuity. The lubrication characteristics of the FIP are more sensitive to changes in the groove width than to changes in other design variables. Moreover, the application of a groove is more effective under low viscosity conditions. The smaller the distance from the edge of the stem part to the first groove in the case of shallow grooves, the better are the lubrication characteristics of the FIP. In contrast, in the case of deep grooves, the lubrication characteristics of the FIP improve as the distance increases. The application of shallow grooves is more effective for improving the lubrication characteristics than the application of deep grooves.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.3
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• pp.991-996
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• 2015

Side population (SP) cells have stem cell-like properties with a capacity for self-renewal and are resistant to chemotherapy and radiotherapy. Therefore the presence of SP cells in human breast cancer probably has prognostic value. Objective: To investigate the characteristics of SP cells and identify the relationship between the SP cells levels and clinico-pathological parameters of the breast tumor and disease-free survival (DFS) in breast cancer patients. Materials and Methods: A total of 122 eligible breast cancer patients were consecutively recruited from January 1, 2006 to December 31, 2007 at Yunnan Tumor Hospital. All eligible subjects received conventional treatment and were followed up for seven years. Predictors of recurrence and/or metastasis and DFS were analyzed using Cox regression analysis. Human breast cancer cells were also obtained from fresh human breast cancer tissue and cultured by the nucleic acid dye Hoechst33342 with Verapami. Flow cytometry (FCM) was employed to isolate the cells of SP and non-SP types. Results: In this study, SP cells were identified using flow cytometric analysis with Hoechst 33342 dye efflux. Adjusted for age, tumor size, lymph nodal status, histological grade, the Cox model showed a higher risk of recurrence and/or metastasis positively associated with the SP cell level (1.75, 1.02-2.98), as well as with axillary lymph node metastasis (2.99, 1.76-5.09), pathology invasiveness type (1.7, 1.14-2.55), and tumor volume doubling time (TVDT) (1.54, 1.01-2.36). Conclusions: The SP cell level is independently associated with tumor progression and clinical outcome after controlling for other pathological factors. The axillary lymph node status, TVDT and the status of non-invasive or invasive tumor independently predict the prognosis of breast cancer.

• Journal of Korea Water Resources Association
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• v.54 no.6
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• pp.407-418
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• 2021

In this study, the two-dimensional flow model, Nays2DH, and driftwood dynamics model were combined to analyze the flow and driftwood behavior depending on the characteristics of the inflow of driftwood and the length of the driftwood stem. In particular, the Dashpot-spring model was added to the driftwood dynamics model to simulate the collision motion of the driftwood, and the wood jam characteristics by the collision of the driftwood were compared. As a result of the simulation, the pass rate of the obstacle section, the travel distance of wood jam, and the mean position of the wood pieces were respondent sensitively by the length of the driftwood stem, but the cohort size of the driftwood supply was insignificant excepting for the pass rate. Through this study, we could understand the interaction between hydraulic structures and driftwood, and through this, it is believed that it will be helpful in establishing a durable maintenance plan for hydraulic structures by predicting the transport and jam formation phenomena of driftwood in advance.

• International Journal of Oral Biology
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• v.32 no.1
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• pp.13-22
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• 2007

The stem cell research is emerging as a cutting edge topic for a new treatment for many chronic diseases. Recently, dental stem cell would be possible for regeneration of tooth itself as well as periodontal tissue. However, the study of the cell characterization is scarce. Therefore, we performed the genetic profiling and the characterization of mouse fetus/neonate derived dental tissue and cell to find the identification during dental development. We separated dental arch from mandibles of 14.5 d fetal mice and neonate 0 d under the stereoscope, and isolated dental cells primarily from the tissues. Then, we examined morphology and the gene expression profiles of the primary cells and dental tissues from fetus/neonate and adult with RT-PCR. Primary dental cells showed heterogeneous but the majority was shown as fibroblast-like morphology. The change of population doubling time levels (PDLs) showed that the primary dental cells have growth potential and could be expanded under our culture conditions without reduction of growth rate. Immunocytochemical and flow cytometric analyses were performed to characterize the primary dental cell populations from both of fetus (E14.5) and neonate. Alpha smooth muscle actin (${\alpha}-SMA$), vimentin, and von Willebrand factor showed strong expression, but desmin positive cells were not detected in the primary dental cells. Most of the markers were not uniformly expressed, but found in subsets of cells, indicating that the primary dental cell population is heterogeneous, and characteristics of the populations were changed during culture period. And mesenchymal stem cell markers were highly expressed. Gene expression profile showed Wnt family and its related signaling molecules, growth factors, transcription factors and tooth specific molecules were expressed both fetal and neonatal tissue. The tooth specific genes (enamelin, amelogenin, and DSPP) only expressed in neonate and adult stage. These expression patterns appeared same as primary fetal and neonatal cells. In this study we isolated primary cells from whole mandible of fetal and neonatal mice. And we investigated the characteristics of the primary cells and the profile of gene expressions, which are involved in epithelial-mesenchymal interactions during tooth development. Taken together, the primary dental cells in early passages or fetal and neonatal mandibles could be useful stem cell resources.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.252.2-252.2
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• 2010

Biomass is considered to be a major potential fuel and renewable resource for the future. In fact, there is high potential to produce the large amount of energy from biomass around the world. In this study, to obtain basic data for practical application of wood pellet and wood pellet boiler system as heating system in agriculture, agricultural biomass resources were surveyed, pellet was made of agricultural by-product such as stem of rape, oat and rice, ricehusk and sawdust and wood pellet boiler system with capacity of 116 kW was manufactured and installed in greenhouse of $38.5m{\times}32m$. High heating value, bulk density and ash content of pellet made of agricultural by-product and efficiency and heating performance of this system was estimated. Rice straw was the largest agricultural biomass in 2005 and the total amount of rice straw converted into energy of $131.71{\times}10^{11}$ kJ. And in 2005, total amount of forest' by-product converted into energy of $29,277.05{\times}10^{11}$ kJ. High heating values of pellets made of agricultural by-products of stem and seed of rape, stem of oat, rice straw and rice husk were 16,034, 16,026, 16,089, 15,650, 15,044 kJ/kg respectively. High heating values of pellets made of agricultural by-products were 83.6% compared to that of wood pellet. Average bulk density of pellets made of agricultural by-products of stem and seed of rape, stem of oat, rice straw and rice husk was 1,400 $kg/m^3$. Ash contents of the pellets were 6.6, 7.0, 6.2, 5.5, 33% respectively. Ash content of rice husk pellet was the largest compared to other kind of pellets. To increase efficiency of agricultural pellet boiler, the boiler adopted secondary heat exchanger. The agricultural pellet boiler designed and manufactured in this study had high efficiency of 84.2% compared to the conventional agricultural pellet boiler, when water flow rate, exhaust gas temperature and average combustion furnace temperature were 39L/min, $180^{\circ}C$, $680^{\circ}C$ respectively. And pellet supplying and pausing time were 13, 43 seconds respectively. In March of 2010, prices of wood pellet, agricultural tax free diesel, diesel, kerosene were 350 won/kg, 811 won/L, 1,422 won/L, 976 Won/L respectively. Also in terms of energy, prices per same heating value were 77.8, 90.1, 158, 108.4 Won/Mcal. Energy saving rate of wood pellet was 16, 50, 39% compared to agricultural tax free diesel, diesel and kerosene respectively.

• Development and Reproduction
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• v.21 no.1
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• pp.47-54
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• 2017

Unlike mouse results, cloning efficiency of nuclear transfer from porcine induced pluripotent stem cells (piPSCs) is very low. The present study was performed to investigate the effect of cell cycle inhibitors on the cell cycle synchronization of piPSCs. piPSCs were generated using combination of six human transcriptional factors under stem cell culture condition. To examine the efficiency of cell cycle synchronization, piPSCs were cultured on a matrigel coated plate with stem cell media and they were treated with staurosporine (STA, 20 nM), daidzein (DAI, $100{\mu}M$), roscovitine (ROSC, $10{\mu}M$), or olomoucine (OLO, $200{\mu}M$) for 12 h. Flow Cytometry (FACs) data showed that piPSCs in control were in G1 ($37.5{\pm}0.2%$), S ($34.0{\pm}0.6%$) and G2/M ($28.5{\pm}0.4%$). The proportion of cells at G1 in DAI group was significantly higher than that in control, while STA, ROSC and OLO treatments could not block the cell cycle of piPSCs. Both of viability and apoptosis were affected by STA and ROSC treatment, but there were no significantly differences between control and DAI groups. Real-Time qPCR and FACs results revealed that DAI treatment did not affect the expression of pluripotent gene, Oct4. In case of OLO, it did not affect both of viability and apoptosis, but Oct4 expression was significantly decreased. Our results suggest that DAI could be used for synchronizing piPSCs at G1 stage and has any deleterious effect on survival and pluripotency sustaining of piPSCs.

• Natural Product Sciences
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• v.21 no.3
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• pp.192-195
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• 2015

An antibacterial benzoquinone, 2,6-dimethoxy-1,4-benzoquinone, isolated from Ficus foveolata stems was used as a standard marker for establishment of quantitative HPLC analysis for the stem extracts of F. foveolata. The method utilized a TSK-gel ODS-80Ts column (5 μm, 4.6 × 250 mm) with the mixture of methanol and 5% acetic acid in water (24:76, v/v) as the mobile phase at a flow rate of 1 mL/min, and quantitative detection at 289 nm. The parameters i.e. linearity, intraday and interday precision, accuracy, specificity and sensitivity of the method were evaluated for method validation. The recoveries of the method were 99.5 - 103.6% and good linearity (R² ≥ 0.9999) was obtained. A high degree of specificity, sensitivity as well as repeatability and reproducibility (RSD less than 2 and 5%, respectively) were also achieved. Chloroform was served as the most suitable solvent for extraction of 2,6-dimethoxy-1,4-benzoquinone. The optimised sample preparation and HPLC method can be practically used in the routine quality control process of F. foveolata stem extracts.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.6
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• pp.657-667
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• 2016

Critical limb ischemia (CLI) is one of the most severe forms of peripheral artery diseases, but current treatment strategies do not guarantee complete recovery of vascular blood flow or reduce the risk of mortality. Recently, human bone marrow derived mesenchymal stem cells (MSCs) have been reported to have a paracrine influence on angiogenesis in several ischemic diseases. However, little evidence is available regarding optimal cell doses and injection frequencies. Thus, the authors undertook this study to investigate the effects of cell dose and injection frequency on cell survival and paracrine effects. MSCs were injected at $10^6$ or $10^5$ per injection (high and low doses) either once (single injection) or once in two consecutive weeks (double injection) into ischemic legs. Mice were sacrificed 4 weeks after first injection. Angiogenic effects were confirmed in vitro and in vivo, and M2 macrophage infiltration into ischemic tissues and rates of limb salvage were documented. MSCs were found to induce angiogenesis through a paracrine effect in vitro, and were found to survive in ischemic muscle for up to 4 weeks dependent on cell dose and injection frequency. In addition, double high dose and low dose of MSC injections increased vessel formation, and decreased fibrosis volumes and apoptotic cell numbers, whereas a single high dose did not. Our results showed MSCs protect against ischemic injury in a paracrine manner, and suggest that increasing injection frequency is more important than MSC dosage for the treatment CLI.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.2
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• pp.92-97
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• 2006

Hull forms of a high speed small boat have been developed through numerical studies. A round bilge type hull form has been drived form a using chine hull form with HCAD, a hull form variation software. Wave resistance and the flow fields around the ships have been computed using well-known software, WAVIS. This software employs Rankine source method with non-linear tree surface condition as well as dry transom boundary conditions. The round bilge hull form showed better resistance performance than to the chine hull form for the whole speed range. However, considering the building and labor costs of the small shipyard, the chine hull form has been selected and its wave resistance characteristics has been improved by modifying the bow regions and applying the stem wedge. It is found that the effect of stem wedge is quite satisfactory to improve the resistance characteristics of high speed chine hull form.