• Restorative Dentistry and Endodontics
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• v.35 no.3
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• pp.211-221
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• 2010

Proteoglycan is highly hydrophilic and negatively charged which enable them attract the water. The objective of study was to investigate the effects of Proteoglycan on microtensile bond strength of dentin adhesives and on architecture of dentin collagen matrix of acid etched dentin by removing the chondroitin sulphate attached on Proteoglycan. A flat dentin surface in mid-coronal portion of tooth was prepared. After acid etching, half of the specimens were immersed in 0.1 U/mL chondroitinase ABC (C-ABC) for 48 h at $37^{\circ}C$, while the other half were stored in distilled water. Specimens were bonded with the dentin adhesive using three different bonding techniques (wet, dry and re-wet) followed by microtensile bond strength test. SEM examination was done with debonded specimen, resin-dentin interface and acid-etched dentin surface with/without C-ABC treatment. For the subgroups using wet-bonding or dry-bonding technique, microtensile bond strength showed no significant difference after C-ABC treatment (p > 0.05). Nevertheless, the subgroup using rewetting technique after air dry in the Single Bond 2 group demonstrated a significant decrease of microtensile bond strength after C-ABC treatment. Collagen architecture is loosely packed and some fibrils are aggregated together and relatively collapsed compared with normal acid-etched wet dentin after C-ABC treatment. Further studies are necessary for the contribution to the collagen architecture of noncollagenous protein under the various clinical situations and several dentin conditioners and are also needed about long-term effect on bond strength of dentin adhesive.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.20 no.4
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• pp.305-315
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• 1998

The fibrous layer of mandibular condyle of the neonatal, 1-, 7-, 14-, 27-, 55-days and 1 year old rats were examined in the electron microscope with particular attention to the ultrastructure and diameter of collagen fibrils. In the 1-day rats, most of the cells of the fibrous layer were undifferentiated mesenchymal cells and fibroblasts with rough a little developed rough endoplasmic reticulum(RER) and golgi apparatus(GA). In 7-, 17 and 27-days old rats, most of the fibroblast showed well developed GA and RER with widely distended cisternae containing granular materials. In many of these cells contained intracytoplasmic filaments among the cytoplamic organelle. In 55-day and 1-year old rats, three types of cells were observed, ie, cells containing well developed cytoplasmic organelle presumed to be involved in the collagen fibril synthesis, cells showing well developed lysosomes, golgi apparatus, mitochondria and short cytoplasmic process presumed to be involved in the active resorption of the injured collagen fibrils or cellular debris, cells containing many intracytoplasmic filaments and a little organelle presumed to be cells of inactive state. The average diameters of collagen fibrils were similar in 1- and 7-day old rats as $38.48{\pm}3.81nm$, $38.06{\pm}3.86nm$. That was thickest in 14 days old rats as $50.21{\pm}3.93nm$ among experimental groups. They were gradually thinner in 27-, 55-day rats as $40.05{\pm}2.52nm$, $43.63{\pm}1.20nm$ and thinnest in 1-year old rats as $37.38{\pm}2.17nm$. The distribution pattern of diameters of collagen fibrils were unimordal with peak of 30-60nm in rats from 1-day to 17-day old. With aging from 27-day to 1 year old rats, collagen fibril diameters showed wide distribution pattern and percentage of thin collagen fibrils increased. These results may show the functional adaptation of fibrous layer of mandibular condyle to the increased mechanical forces with aging.

• Korean Journal of Comparative Education
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• v.26 no.4
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• pp.81-103
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• 2016

The reform of teacher policies to raise the quality of teachers has been one of the major priorities of countries around the world. Especially, the structure of elementary and secondary teacher education institutions has been the focus of international teacher policy reform agenda. Despite the problems faced by Korean teacher education system, the reform policy effort has not been actively pursued. Based on this problem recognition, this study seeks to analyze the case of Ireland to reveal the characteristics of teacher education system restructuring including background of restructuring, key strategies, and major contents. We found that the restructuring of Irish system was triggered by both domestic and international initiatives to tackle the problems of the system. The restructuring effort was led by the government and showed several distinctive features, such as reducing the number of institutions, combining elementary and secondary teacher education institutions, and strengthening research capacity of institutions. Base on the findings, a few policy recommendations were made to reignite the discussions on the reform of teacher education system in South Korea.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.318-332
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• 2000

The purpose of this study was to investigate the effects of demineralized freeze-dried bone (DFDB) on mechanically exposed pulp of dog by evaluating the pulpal inflammation and healing process, formation of dental hard tissue, and structural changes of fibroblasts of the remaining pulp tissue. Teeth of 4 dogs, weighing 10kg, were used in this study. Class V cavities were prepared followed by exposed the pulp tissue mechanically by sterilized round bur. In control group, exposed pulps were capped with calcium hydroxide paste followed by sealed with IRM. In experimental groups, the exposed pulps of one group were capped with the collagen and those of the other group were capped with DFDB. All cavities were sealed with same manor as control group. The animals were sacrificed at the intervals of 3, 7, 14, and 28 days for histopathlogic evaluation. The specimens were observed by the light microscope and trans-electron microscope. The results were as follows: 1. Pulp necrosis was not observed in all groups. Inflammatory response was disappeared from 1 week in control group and group 2. But it was not disappeared until 2 weeks and also irregular arrangement of odontoblasts was showed at the lateral walls of root canal just beneath the amputated site of the pulp in group 1. 2. Dentinal bridge was formed incompletely at 2 weeks but it was formed completely at 4 weeks in control group. Odontoid tissue was also found in control group at 4 weeks from treatment. Amputated site of pulp was encapsulated with fibrous tissue and odontoblast and dentinal bridge was not found in group 1. Preodontoid tissue and reparative dentin which were formed by odontoblast differentiated around DFDB were found, but dentinal bridge was not found in group 2. 3. Cell with large basophillic-stained nuclei infiltrated to amputated site and DFDB at 1 week from treatment in control group and group 2. They were found more in group 2 than in control group. Odontoblasts arranged more regularly and reparative dentin was found more as time elapsed. 4. Dentin-formative odontoblasts which showed ultramicrostructure of cytoplasm with polarized nucleus, rEM, Golgi complex, secretory granules, secretion of organic matrix in control of group and group 2. In regards to above results, the demineralized freeze-dried bone(DFDB) induce odontoblastic differentiation and further come up to the dentin formation in amputated pulp.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.117-120
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• 2020

본 논문은 인공지능 메이커 교육과 관련한 요소를 논문 네트워크 키워드 분석과 다양한 빅데이터를 종합하여 핵심용어를 선정 후 인공지능 메이커 교육을 시스템 다이내믹스의 Vensim프로그램으로 인과지도(Casual Loop Diagramming)를 구조분석(모델의 구조)하여 예측 결과를 토대로 향후 미래 상황 추출 및 정책 결정 연구에 영향을 기여한다. 연구 결과 인공지능 교육 정책은 추후 인공지능 교육과 메이커 교육을 융합한 교육 관련 산업이 증대할 것으로 예측되며 교육 경쟁력 향상과 창의적 인재 양성, OTT를 이용한 인공지능 교육 콘텐츠 향상으로 학습에 활용성이 증대하게 된다. 또한 인공지능 교육 정책은 프로그래밍 교육으로 연결되어 성장기 학습자들의 사고력과 정서 발달에 도움 되며 다양한 교재 및 기기 등장으로 인한 학습에 다양성 역시 증가할 것으로 예측된다. 학교 차원에서는 교수·연구 지원 활동이 증가하여 수업 전문성을 가진 교사가 늘어나 학교 교육의 질은 확대되고 학부모는 인공지능 교육 정책에 긍정적으로 된다. 시스템 다이내믹스는 구조가 형태를 결정짓는다는 세계관에 기초하여 피드백 루프와 동태적 형태 유형을 파악하며 다양한 가능성이 존재하게 된다. 이는 추후 다양한 연구를 통해 인공지능 교육 정책 인과지도의 확대로 연결될 수 있음을 암시하며 본 논문을 통해 인공지능 교육 연구 확산에 시발점이 되었으면 한다.

• Journal of Life Science
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• v.20 no.12
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• pp.1838-1843
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• 2010

Skin aging is related to genetic and environmental factors (e.g., gene mutation and UV radiation respectively). To develop a new anti-wrinkle cosmetic or functional food by using Korean rice wine cake, we examined the effects of Korean rice wine cake, a brewery byproduct, on antioxidant effect, collagen synthesis and expression of MMP-1. Interestingly, we found that Korean rice wine cake has the ability to promote scavenging activity of DPPH radical. We also found that the cell proliferation and synthesis of collagen in HS27 cells was increased by Korean rice wine cake in a concentration-dependent manner. However, elastase inhibitory activity was not changed. In addition, the expression of MMP-1 was inhibited by Korean rice wine cake in a concentration-dependent manner. All these results suggest that Korean rice wine cake can be effectively used for the prevention of wrinkles in human skin.

• Parasites, Hosts and Diseases
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• v.28 no.3
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• pp.155-160
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• 1990

The tribocytic organ and tegument of Fibricola seeulensis were examined histochemically for the detection of carbohydrates, mucosubstances, amyloid, collagen and alkaline phosphatase. The surface, secretes, gland cells of the tribocytic organ, and the tegument of the worms were positive to periodic acid Schig (PAS) and PAS with diastase stain but negative to other stains. It was inferred that the tribocytic organ and tegument of F. seoulensis comprise neutral mucopolysaccharides, which may take a protective role against host enzymes. The surface and secretes of the tribocytic organ, and the tegument of the worms were also Positive to double bridge PAP for alkaline phosphatase. This fact suggests that they may play a role as both self protective and host tissue Iytic functions.

• Applied Microscopy
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• v.34 no.4
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• pp.277-283
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• 2004

This paper reports that the ultrastructural nature of the interface process between the implants and surrounding bone has been studied after in vivo 1, 4, 8, 12 weeks of implantation of smooth machined implants into rabbit tibias. There was no indication of the fibrous connective tissue formation around the implant that imply intolerance of the bone tissue towards the implant after 1 week of implantation. The regions showing direct bone tissue bonding to the smooth machined implant contained osteoblast activating across the interface in the direction after 4 weeks of implantation. The reaction of a smooth machined implant caused in the first instance formation of an amorphous woven bone, which transformed into a mineralized bone containing collagen fibers. After 8 weeks of implantation, the activities of osteoblast initiated osseointegration forming bone matrix at the interface. During this period, the osteoblast surrounded with a matrix consisting of collagen bundles running in various directions. In the interface area between newly formed bone tissue and implants which has been inserted in rabbit tibias for 12 weeks, the implant and mineralized bone was separated by an amorphous electron dense material layer about $1{\sim}1.5{\mu}m$ in thickness.

• Applied Microscopy
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• v.30 no.2
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• pp.213-232
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• 2000

The development of the knee joint was studied by electron microscopy in human fetuses ranging from 20 mm to 260 mm crown-rump length ($7\sim30$ weeks of gestational age). The appearance of the primordium of the meniscus and cruciate ligament was conspicuous as the mesenchymal cells , preceeding that of joint space at 30 mm fetus. The primitive joint cavity was first seen in the interzone from the 40 mm fetus and its intermediate layer proceeded developing as a narrow cleft which was closely incorporated with two chondrogenic layers. Poorly differentiated mesenchymal cells of the meniscus at 40 mm fetus containing predominantly free ribosomes differentiated into fibroblasts at 60 mm fetus. By 100 mm fetus, the fibroblast in inner zone of the meniscus presented as oval profiles with a short cell processes, whereas middle and peripheral zones presented as elongated cells. Differentiation of the synovial membrane coincided with clarification of the joint cavity When dilatation of the synovial cavity occurred, the two types of synovial cells were identified at 60 mm fetus. By 100 mm fetus a majority of the intimal cells were B-type. B-type cells were clearly distinguishable from A-type cells by their content of extensive rough endoplasmic reticula and well developed Golgi complexes. In contrast, A-type cells had numerous filopodia, pinocytotic vesicles, lysosomes and large vacuoles. At 260 mm fetus the B-type cells were also a majority of intimal cells. At 260 mm fetus the inner zone of the meniscus was filled with parallel oriented fascicles of collagenous fibers and oval fibroblasts. The middle zone was constituted of parallel and radially arranged fibers and fibroblasts. The outer zone was populated by elongated fibroblasts encircled by crossed collagenous fibers with the blood vessels. At 30 mm fetus the fibroblasts of the cruciate ligament contained rough endoplasmic reticula and mitochondria. Collagen fibrils were noted within narrow cytoplasmic processes which were continued with the extracellular space. Collagen fibrils of ligament were filled in the bulk of extracellular space at 100 mm fetus. By $150\sim260mm$ fetus, the cruciate ligaments were constituted of longitudinally oriented bundle of collagen fibrils with irregular rows of round cells between.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.2 no.2
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• pp.185-193
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• 1999

Purpose: Proliferation of bile duct-like structures and fibrosis is a hepatic cellular reaction observed in most forms of human liver disease and in a variety of experimental conditions associated with liver injury. The aim of this study was to investigate the activation of Ito cells and bile duct proliferation in the rat after common bile duct ligation (CBDL). Methods: Hepatic morphological abnormalities were examined in rats whose bile ducts had been irreversibly ligated for 15, 21, 24 and 28 days. The liver was examined by immunohistochemical staining for ${\alpha}$-smooth muscle actin, the known marker of activated Ito cells, and light and electron microscopes. Results: After CBDL, the bile canalicular proliferation and interstitial fibrosis were gradually increased in the periportal areas extended to hepatic sinusoids. Ito cells positive for ${\alpha}$-smooth muscle actin were frequently observed in the periductular space and in perisinusoidal space of Disse. Ito cells and myofibroblasts were gradually increased in the interstitial fibrosis until the 28th day after CBDL. Ito cells and myofibroblasts had microfilaments with dense body at the periphery of the cell. Conclusions: Our results suggest that Ito cells may be fibroblastic or myogenic. It has also been postulated that during the development of hepatic fibrosis, Ito cells become myofibroblasts or fibroblast like cells.