• Applied Microscopy
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• v.23 no.1
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• pp.91-108
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• 1993

The relationship of cartilage canals to initial osteogenesis of primary ossification center of developing vertebrae in human fetuses ranging from 50mm to 260mm in crown rump length was studied by light and electron microscopy. The cartiage canals of the thoracic vertebrae were first observed at 60mm fetus. Cartilage canals were identified as vascular channels arising from perichondrium surfaces. A number of cartilage canals were observed around the primary center of ossification at 80mm fetus. At 120mm fetus, cartilage canals of the bodies of vertebra were increased. Eventually the canals were eroded from the main medullary cavity and remained at only peripheral regions of growth cartilage. Superficial, intermediate, and deep canals were identified by the characteristics of cartilage cells. Fibroblasts, undifferentiated mesenchymal cells, and vacuolated macrophages were observed adjacent to the matrix of resting cartilage cells in the superficial canal. Fibroblasts and mesenchymal cells were densely packed at the tip of canal, giving an epithelial appearance to the clustered cell in the intermediate canal. Vacuolated macrophages were in contact with matrix of hypertrophied cartilage. The thick-walled vessels in the intermediate and deep canals consisted of typical endothelial cells, but in the newly formed vessels contained mesenchymal cells and fibroblasts incorporated into the vessel wall. During lengthening of cartilage canal, the matrix of cartilage cells were invaded by newly formed capillaries and vacuolated macrophages. At the deep canal, the lateral wall of the canal terminated in matrix containing calcified cartilage. The mesenchymal cells began to differentiate into osteoblasts adjacent to the calcified matrix. The results indicate that the connective tissue cells within the cartilage canals proliferate and differentiate into osteoblasts at the site of primary ossification center.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.576-580
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• 2017

A dynamic nanoindentation method was applied to study an Fe-18 at.% Gd alloy as a neutron-absorbing material prepared by vacuum arc-melting and cast in a mold. The Fe-18 at.% Gd cast alloy had a microstructure with matrix phases and an Fe-rich primary dendrite of $Fe_9Gd$. Rietveld refinement of the X-ray spectra showed that the Fe-18 at.% Gd cast alloy consisted of 35.84 at.% $Fe_3Gd$, 6.58 at.% $Fe_5Gd$, 16.22 at.% $Fe_9Gd$, 1.87 at.% $Fe_2Gd$, and 39.49 at.% ${\beta}-Fe_{17}Gd_2$. The average nanohardness of the primary dendrite phase and the matrix phases were 8.7 GPa and 9.3 GPa, respectively. The fatigue limit of the matrix phase was approximately 37% higher than that of the primary dendrite phase. The dynamic nanoindentation method is useful for identifying local phases and for analyzing local mechanical properties.

• Korean Journal of Head & Neck Oncology
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• v.20 no.1
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• pp.13-18
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• 2004

Objectives: Cancer lethality is usually the result of local invasion and metastasis of neoplastic cell from the primary tumor. Because of their ability to degrade extracellular matrix components, matrix metalloproteinases (MMPs) and basic fibroblast growth factor (bFGF) have been implicated in the breakdown of basement membrane and underlying stroma, thereby facilitating tumor growth and invasion. It has been well established that MMPs and bFGF expression correlate with cervical lymph node metastasis, but studies on expression in the metastatic cervical lymph node itself are not enough. We have analyzed matrix metalloproteinases (MMPs) and basic fibroblast growth factor (bFGF) in squamous cell carcinoma of the head and neck and metastatic cervical lymph node, and evaluated their relationship and clinicophathologic significance. Material and Methods: 20 cases of squamous cell carcinoma of the head and neck were entered on the study of immunohistochemical stains for MMP-9 and bFGF in the obtained tissue from primary tumor and metastatic cervical lymph node. We analyzed the relationship between MMP-9, bFGF expression of the primary tumor and metastatic node with age, sex, T-stage, N-stage, histologic grade, pathologic stage and disease free survival. Results: Expression of MMP-9 and bFGF in cancer cell and metastatic lymph node was higher than that in normal cell and lymph node. According to histologic differentiation, expression of MMP-9 of the metastatic cervical lymph node was higher than primary tumor. Considering to other clinicopathologic factor, no statistical significance was seen in MMP-9 and bFGF. Conclusion: We found that expression of MMP-9 is higher in the metastatic lymph node than primary tumor in the poorly differentiated squamous cell carcinoma. But we don't find out the statistical significance in relation between bFGF and clinical factors. So we guess that some different mechanism of MMP-9 and bFGF in Head & Neck squamous cell carcinoma exist. Further studies will be necessary to establish their pathogenesis in the Head and Neck cancer.

• Journal of Magnetics
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• v.4 no.1
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• pp.1-4
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• 1999

The microstructure and magnetic properties of$ Fe_{87}Zr_7Si_4B_2$ nanocrystalline alloys were studied by magnetization measurements and M ssbauer spectrometry over a wide temperature range. Three well resolved spectral components have been found and attributed to bcc-Fe grains (with almost pure iron structure), residual amorphous matrix enriched with solute elements and interfaces formed at the grain-matrix boundaries. It has been shown that, contrary to the expectation, during crystallization the atomic segregation occurs leading to the formation of primary bcc-Fe grains and the partition of Si atoms into the residual amorphous matrix.

• Journal of Korea Foundry Society
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• v.20 no.2
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• pp.89-96
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• 2000

The effects of modification processing on the refinement of primary Si and the wear behavior of hyper-eutectic Al-Si alloys have been mainly investigated. Refining effects of primary Si in Al-17%Si alloy was more efficient than that of B.390 alloy. Optimum condition of getting the finest primary Si microstructure was when AlCuP modifier is added into the melt at $750^{\circ}C$ and held it at $700^{\circ}C$ for 30 minutes. Wear loss in the specimens of as-cast condition decreases as the size of primary Si decreases, in the order of B.390 alloy, B.390 alloy with AlCuP addition, Al-17%Si alloy and Al-17%Si alloy with AlCuP addition. Wear loss in the aged condition of Al-17%Si alloy, B.390 alloy and B.390 alloy with AlCuP addition decreased due to the increase of compressive residual stress in the matrix by the aging treatment. While, wear loss increased in the aged specimens of Al-17%Si alloy with AlCuP addition and Hepworth addition in which compressive residual stress decreases by the aging treatment. Therefore, it is assumed that higher compressive residual stress in the matrix can reduce the wear loss in composite materials such as hyper-eutectic Al-Si alloys.

• Journal of Periodontal and Implant Science
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• v.34 no.4
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• pp.759-769
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• 2004

Periodontal therapy has dealt primarily with attempts at arresting progression of disease, however, more recent techniques have focused on regenerating the periodontal ligament having the capacity to regenerate the periodontium. The effect of chitosan, a carbohydrate biopolymer extracted from chitin, on periodontal ligament regeneration is of particular interest. The purpose of this study was to evaluate the effect of chitosan on the expression of extracellular matrix proteins in primary rat calvarial cells in Vitro. In the control group, cells was cultured with BGjb media. In the experimental groups, cells were cultured with chitosan in concentration of 0.01, 0.1, 1.0 and 2.0 mg/ml. Then each group was characterized by examining alkaline phosphatase activity at 3 and 7 days, and the ability to produce mineralized nodules of rat calvarial cells at 14 and 21 days. Synthesis of type I collagen (COL-I), osteocalcin (OCN), bone sialoprotein (BSP) was evaluated by RT-PCR at 14 days. The results were as follows: 1. Alkaline phosphatase activity was significantly higher in the concentration of chitosan 0.01mg/ml, 0.1mg/ml and 1.0mg/ml compared to control (p<0.05). 2. The percentage of mineralized bone nodule was more in the concentration of chitosan 0.1mg/ml and 1.0mg/ml than the control. 3. At 14 day culture, the expression of OCN was increased by chitosan in concentration of 1.0 mg/ml and 2.0 mg/ml. These results suggested that chitosan in concentration of 0.1 and 1,0 mg/ml stimulate the extracellular matrix of primary rat calvarial cells and may facilitate the formation of bone.

• Archives of Plastic Surgery
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• v.43 no.5
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• pp.424-429
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• 2016

Background The objective of this paper was to describe a novel technique for improving the maintenance of nipple projection in primary nipple reconstruction by using acellular dermal matrix as a strut in one of three different configurations, according to the method of prior breast reconstruction. The struts were designed to best fill the different types of dead spaces in nipple reconstruction depending on the breast reconstruction method. Methods A total of 50 primary nipple reconstructions were performed between May 2012 and May 2015. The prior breast reconstruction methods were latissimus dorsi (LD) flap (28 cases), transverse rectus abdominis myocutaneous (TRAM) flap (10 cases), or tissue expander/implant (12 cases). The nipple reconstruction technique involved the use of local flaps, including the C-V flap or star flap. A $1{\times}2-cm$ acellular dermal matrix was placed into the core with O-, I-, and L-shaped struts for prior LD, TRAM, and expander/implant methods, respectively. The projection of the reconstructed nipple was measured at the time of surgery and at 3, 6, and 9 months postoperatively. Results The nine-month average maintenance of nipple projection was $73.0%{\pm}9.67%$ for the LD flap group using an O-strut, $72.0%{\pm}11.53%$ for the TRAM flap group using an I-strut, and $69.0%{\pm}10.82%$ for the tissue expander/implant group using an L-strut. There were no cases of infection, wound dehiscence, or flap necrosis. Conclusions The application of an acellular dermal matrix with a different kind of strut for each of 3 breast reconstruction methods is an effective addition to current techniques for improving the maintenance of long-term projection in primary nipple reconstruction.

• Journal of Korea Foundry Society
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• v.23 no.3
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• pp.130-136
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• 2003

Rheocasting of AZ91D magnesium alloys yielded the microstructure consisted of the spherical primary particles in the matrix which is different from conventional casting. Rheocast ingots were produced under various processing conditions using batch type rheocaster. Morphology of primary particles was changed from rosette-shape to spherical shape with increasing stirring rate$(V_s)$ and decreasing isothermal stirring temperature$(T_s)$. With increasing $V_s$, more effective shearing between the particles occurred rather than the agglomeration and clustering, so the primary particle size decreased. But with decreasing $T_s$, primary particle size increased mainly due to sintering and partially Ostwald ripening. The sphericity of primary particles increased with increasing $V_s$ and decreasing $T_s$ due to enhanced abrasion among the primary particles. The uniformity of primary particle size increased with increasing Vs and $T_s$.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.3
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• pp.157-163
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• 2005

Effects of refinement of primary Si and residual stress on the mechanical properties of Aluminum B.390 alloy have been examined. Calcium was found to have an effect on the size of primary silicon particles. Primary silicon particle was refined as Ca content decreased. Refinement of primary Si particles led to an improvement in mechanical properties of the alloy; increase of elongation was prominent, above all. By the increase of compressive residual stress in the matrix alloy, tensile strength increased but elongation decreased.

• Speech Sciences
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• v.13 no.1
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• pp.117-128
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• 2006

The two-channel Generalized Sidelobe Canceller (GSC) scheme suffers from the presence of leakage signal in the reference channel. The leakage signal is caused by the dissimilar impulse responses between microphones, and different paths from speech source to microphones. Such leakage is detrimental to speech enhancement of the GSC since the desired reference signal becomes corrupted. In order to suppress the signal leakage, two matrix injection methods are proposed. In the first method, a simple gain compensation matrix is used. In the second, a projection matrix for reducing the error between the actual and the ideal primary and reference signals, is used. This paper describes the performance degradation resulting from leakage, and proposes effective methods to resolve the problem. Representative experiments were conducted to demonstrate the effectiveness of the proposed methods on recorded speech and noise in an actual automobile environment.