• Journal of Biomedical Engineering Research
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• v.17 no.1
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• pp.61-70
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• 1996

In cementless total hip arthroplasty(THA), an initial stability of the femoral component is mandatory to achieve bony inyowth and secondary long term fixation. Primary stability of the femoral component can be obtained by minimizing the magnitude of relative micromotions at bone stem interface. An accurate evaluation of interf'ace micromotion and stress/strain fields in the bone-implant system may be relevant for better understanding of clinical situations and improving THA design. Recently finite element method(FEM) was introduced in'orthopaedic research field due to its unique capacity to evaluate stress in structure of complex shape, loading and material behavior. The authors developed the 3-dimensional finite element model of proximal femur with $Multilock^{TM}$ stem of 1179 blick elements to analyse the micromotions and mechanical behaviors at the bone-stem inteface in early post-operative period for the load simulating single leg stance. The results indicates that the values of relative motion for this well fit stem were $150{\mu}m$ in maximum $82{\mu}m$ in minimum and the largest relative motion was developed in medial region of Proximal femur and in anterior-posterior direction. The motion in the proximal bone was much greater than in the distal bone and the stress pattern showed high stress concentration on the cortex near the tip of the stem. These findings indicate that the loading on the hip joint in the early postoperative situation before achieving bony ingrowth could produce large micromotion of $150{\mu}m$ and clinicaly non-cemented THA patient should not be allowed weight bearing strictly early in the postoperative period.

• Journal of Korean Society of Forest Science
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• v.88 no.2
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• pp.195-204
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• 1999

To improve nut production and timber quality in a plantation, crown shape controls were suggested for Korean white pines (Pinus koraiensis) under age class III through the analyses of the crown shape controls for seed orchard trees in several species, of crown status of controlled and uncontrolled trees in a Korean white pine seed orchard, and of growth characteristics of plantation trees under age class III. For nut production from the small trees less than 8 m, modified leader type can be applied by cutting the central leader and all branches below 1 m and keeping 4~5 nodes with 3~4 whorled branches a node locating 1 m apart. Trees with a 4~8 m long trunk below the first living branch are shaped into trees for nut and timber production, which have a 4~8 m long knotless stem and a modified leader type crown with 4~5 nodes with 3~4 whorled branches a node at a distance of 1 m. Trees, showing the first living branch at or above 9 m from the surface, are pruned severely for timber production and result in a central leader type containing two fifths of the initial crown. It is advisable to remove the leader and the branches when collecting cones or after/during October to take advantage of easy labor and little resin while cutting. After stem cut, branches showing apical dominance are to be cut to control height when necessary. The removal of the uppermost node may be needed to control the crown shape several years after the initial stem-cut.

• The Plant Pathology Journal
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• v.21 no.1
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• pp.83-85
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• 2005

Ditylenchus acris was isolated from diseased strawberry plants. Frequently, D. acris and Aphelenchoides fragariae occur together in a strawberry plant. Both species appeared very similar in the shape, length, swimming behavior and causing symptoms, and difficult to distinguish them by a stereomicroscope. But they were easily distinguished under a compound microscope especially by their tail shape, median bulb, vulva position, and bursa.

• Journal of Biomedical Engineering Research
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• v.29 no.3
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• pp.212-221
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• 2008

The total hip replacement (THR) has been used as the most effective way to restore the function of damaged hip joint. However, various factors have caused some side effects after the THR. Unfortunately, the success of the THR have been decided only by the proficiency of surgeons so far. Hence, It is necessary to find the way to minimize the side effect caused by those factors. The purpose of this study was to suggest the definite data, which can be used to design and choose the optimal hip implant. Using finite element analysis (FEA), the biomechanical condition of bone cement was evaluated. Stress patterns were analyzed in three conditions: cement mantle, procimal femur and stem-cement contact surface. Additionally, micro-motion was analyzed in the stem-cement contact surface. The 3-D femur model was reconstructed from 2-D computerized tomography (CT) images. Raw CT images were preprocessed by image processing technique (i.e. edge detection). In this study, automated edge detection system was created by MATLAB coding for effective and rapid image processing. The 3-D femur model was reconstructed based on anatomical parameters. The stem shape was designed using that parameters. The analysis of the finite element models was performed with the variation of parameters. The biomechanical influence of each parameter was analyzed and derived optimal parameters. Moreover, the results of FE A using commercial stem model (Zimmer's V erSys) were similar to the results of stem model that was used in this study. Through the study, the improved designs and optimal factors for clinical application were suggested. We expect that the results can suggest solutions to minimize various side effects.

• The Korea Journal of Herbology
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• v.33 no.3
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• pp.11-18
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• 2018

Objectives : Saururus chinensis and Houttuynia cordata (Saururaceae) are perennial herbs using for medicinal purposes in Korea. The objectives of this study are to compare anatomical key characters between two medicinal plants and to provide fundamental information for the identification of two herbal medicines by using anatomical features. Methods : Cross-sections of root, rhizome, stem, petiole, and leaf for each species were observed in this study. Materials were analyzed through dehydration, paraffin embedding and micro-sectioning, and double staining with Safranin O and Fast-Green FCF. Observations of permanent preparation were conducted using light microscope. Results : S. chinensis and H. cordata were distinguished with anatomical differentiations; Idioblasts with essential oil were scattered in the parenchyma cell of cortex, pith, and phloem of S. chinensis, on the other hand, in H. cordata, idioblasts were distributed ring-shaped in the cortex of the root. S. chinensis had two cycles of vascular bundles in the stem while H. cordata had one cycle. Hypodermis layer was conspicuous in a stem of H. cordata, crystals were observed the only parenchyma in a stem of S. chinensis, and epidermal oil cells were developed in the epidermis of H. cordata. S. chinensis had air cavity at the cortex and pith of the stem. The shape of cross-section was polygonal in the stem of S. chinensis and was circular in the stem of H. cordata. Conclusions : We investigated anatomical study of Korean S. chinensis and H. cordata. To identify two herbal medicines, we considered main anatomical features and provided identification key here.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.129.1-129
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• 2003

A destructive stem rot of strawberry (cv. Akihime) occurred sporadically in farmers' fields around Daegok-Myeon, Jinju City, Gyeongnam province in Korea. The infected plants showed stem and crown rot, sometimes whole plant blighted. White mycelia spread over stems of infected clones and sclerotia formed on the old lesions near to soil surface. The fungus formed white colony on PDA and showed maximum mycelial growth and scleotial formation around 30$^{\circ}C$. The fungus usually have many narrow mycelial strands in the aerial mycelium and the width were 4.0∼10.0$\mu\textrm{m}$. The typical clamp connections were formed on the mycelium. The shape of sclerotia was globoid and 1.0∼2.8 mm in size. The fungus was isolated repeatedly from the infected tissues and identified as Sclerotium rolfsii. The fungus was inoculated to strawberry and confirmed its pathogenecity This is the first report on the stem rot of strawberry caused by Scierotium rolfsii in Korea.

• Tribology and Lubricants
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• v.31 no.5
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• pp.205-212
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• 2015

In this research, effects of profile changes of stem section of the plunger on the lubrication characteristics of a fuel injection pump (FIP) were evaluated by hydrodynamic lubrication analysis. The clearance between plunger and barrel was divided into two regions, head and stem. The head was not involved in preventing a decrease of fuel oil pressure. So, research efforts were focused on both edges of the plunger’s stem. The two -dimensional Reynolds equation was used to evaluate lubrication characteristics with variations in viscosity, clearance and profile for a laminar, incompressible, unsteady-state flow. Moreover, the equilibrium equation of moment and forces in the vertical and horizontal directions were used to determine the motion of the plunger. The equations were discretized using the finite difference method. Lubrication characteristics of the FIP were investigated by comparing the dimensionless minimum film thickness, or film parameter, which is the ratio of minimum film thickness to surface roughness. Through numerical analyses, we showed that the profile of the lower edge of the stem had no effect on lubrication characteristics, but the profile of the upper edge had a significant influence on lubrication characteristics. In addition, changes in the profile were more effective in improving lubrication characteristics under low viscosity conditions.

• Mycobiology
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• v.30 no.2
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• pp.102-104
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• 2002

In July 2001, a destructive stem rot of tatarian aster(Aster taturicus) was occurred sporadically in exhibition farm of Gyeongsangnam-do Agricultural Research and Extension Services, in Hamyang, Korea. The fungus also caused collar and crown rot and systemic wilt or blight of whole plant. White mycelium spread over stems and petioles of infected plants and sclerotia formed on the old lesions and near the soil surface. The fungus showed maximum mycelial growth was obtained around $30^{\circ}C$ but did not grow below $5^{\circ}C$ or above $45^{\circ}C$. The mycelial width ranges $4.2{\sim}10.4{\mu}m$. and the color is white, usually many narrow mycelial stand grow in the aerial mycelium and formed clamp connection. Numerous sclerotia were formed in artificial media like PDA at $30^{\circ}C$. The shape of sclerotia were sphere and $1.0{\sim}3.2{\mu}m$ in diameter. The fungus was isolated repeatedly from the infected, tissues and confirmed its pathogenecity to aster and identified as Sclerotium rolfsii. This is the first report that Sclerotium rolfsii causes stem rot of tatarian aster in Korea.

• Journal of Korean Society of Forest Science
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• v.98 no.5
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• pp.576-583
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• 2009

Based on the stem analysis and biomass measurement of 36 trees and 1,576 branches in Pinus sylvestris var. mongolica (Mongolian pine) plantations of Northeast China, this study was conducted to develop estimation model equation for leaf biomass of a single tree and branch, to examine the vertical distribution of leaf biomass in the crown, and to evaluate the proportional ratios of biomass by tree parts, stem, branch, and leaf. The results indicated that DBH and crown length were quite appropriate to estimate leaf biomass. The biomass of single branch was highly correlated with branch collar diameter and relative height of branch in the crown, but not much with stand density, site quality, and tree height. Weibull distribution function would have been appropriate to express vertical distribution of leaf biomass. The shape parameters from 29 sample trees out of 36 were less than 3.6, indicating that vertical distribution of leaf biomass in the crown was displayed by bell-shaped curve, a little inclined toward positive side. Apparent correlationship was obtained between leaf biomass and branch biomass having resulted in linear function equation. The stem biomass occupied around 80% and branch and leaf made up about 20% of total biomass in a single tree. As the level of tree class was increased from class I to class V, the proportion of the stem biomass to total biomass was gradually increased, but that of branch and leaf became decreased.

• International Journal of Oral Biology
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• v.48 no.4
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• pp.33-44
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• 2023

In this review, the regulatory mechanisms of autophagy were described, and its interaction with apoptosis was identified. The role of autophagy in embryogenesis, tooth development, and cell differentiation were also investigated. Autophagy is regulated by various autophagy-related genes and those related to stress response. Highly active autophagy occurrences have been reported during cell differentiation before implantation after fertilization. Autophagy is involved in energy generation and supplies nutrients during early birth, essential to compensate for their deficient supply from the placenta. The contribution of autophagy during tooth development, such as the shape of the crown and root formation, ivory, and homeostasis in cells, was also observed. Genes control autophagy, and studying the role of autophagy in cell differentiation and development was useful for understanding human aging, illness, and health. In the future, the role of specific mechanisms in the development and differentiation of autophagy may increase the understanding of the pathological mechanisms of disease and development processes and is expected to reduce the treatment of various diseases by modulating the autophagic phenomenon.