• Journal of Life Science
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• v.31 no.3
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• pp.266-279
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• 2021

The present study examined the cytotoxic effects of a Smilax china L. extract (SCLE) in human cancer (A-549, MCF-7, MDA-MB-231, U87-MG, AGS, MKN-74, and SNU-601) and normal MRC-5 fibroblasts, as well as in mesenchymal stem cells derived from dental tissue (DSC). The 50% inhibitory concentration (IC50) values for SCLE were significantly (p<0.05) lower in the cancer cell lines (A-549, MCF-7, MDA-MB-231, U87-MG, AGS, MKN-74 and SNU-601) than in the MRC-5 and DSC cells. Cell growth was significantly (p<0.05) more inhibited in the cancer cell lines treated with 200 ㎍/ml SCLE than in the normal MRC-5 and DSC, and anoikis-like floating cell morphology was observed in the SCLE-treated cancer cells. The cells detached by SCLE treatment were retrieved daily and assayed for viability and telomerase activity. Cells retrieved at 4 days showed significantly decreased viability and telomerase activity (p<0.05), as well as apoptosis-like abnormal morphology, when compared to cells retrieved in the previous 3 days. The ratio of apoptosis and cells in the G1 phase was significantly (p<0.05) increased in the A-549, AGS, and MCF-7 cancer cells treated with SCLE for 4 days compared to untreated controls. However, after SCLE treatment, cell adhesion was not increased by application of an inhibitor of the associated protein kinase (ROCK) that mainly contributes to the increase in cell attachment. This suggests that the cellular detachment by SCLE is probably controlled by a Rho-independent mechanism(s). These observations indicate that SCLE readily induces anoikis in cancer cells and could serve as a potent agent for cancer chemotherapy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.801-807
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• 2021

In various industrial fields and infrastructure based on electronic components, such as communication equipment, transportation, computer networks, and military equipment, the need for electromagnetic pulse shielding has increased. Two methods for applying electromagnetic pulse shielding are effective. The first is construction using shielding materials, such as shielding concrete, shielding doors, and shielding windows. The other is coating shielding paints on non-shielding structures. Electromagnetic pulse shielding paints are made using conductive materials, such as carbon nanotubes, graphite, carbon black, and carbon fiber. In this paint, electromagnetic pulse shielding performance is added to the commonly used water-based paint. In this study, the shielding effectiveness and bonding performance of paints using conductive graphite and carbon black as shielding materials were evaluated to develop electromagnetic pulse shielding inorganic paints. The shielding effectiveness and bonding performance were evaluated by applying six mixtures composed of different kinds and amounts of shielding material. The mixture of conductive graphite and carbon black at a weight ratio of 1:0.2 was the most effective in shielding as 33.6 dB. Furthermore, the mixture produced using conductive graphite only showed the highest bonding performance of 1.06 MPa.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.6
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• pp.834-841
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• 2022

Recently, applying artificial intelligence technologies in various fields of production has drawn an upsurge of research interest due to the increase for smart factory and artificial intelligence technologies. A great deal of effort is being made to introduce artificial intelligence algorithms into the defect detection task. Particularly, detection of defects on the surface of metal has a higher level of research interest compared to other materials (wood, plastics, fibers, etc.). In this paper, we compare and analyze the speed and performance of defect classification by combining machine learning techniques (Support Vector Machine, Softmax Regression, Decision Tree) with dimensionality reduction algorithms (Principal Component Analysis, AutoEncoders) and two convolutional neural networks (proposed method, ResNet). To validate and compare the performance and speed of the algorithms, we have adopted two datasets ((i) public dataset, (ii) actual dataset), and on the basis of the results, the most efficient algorithm is determined.

• Journal of the Korean Society of Food Culture
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• v.22 no.1
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• pp.157-165
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• 2007

This study was designed to evaluate the effects of fructose(F) or sucrose(S) and guar gum intake on carbohydrate and lipid metabolism in 15-week-old male Goto-Kakizaki(GK) rats. Fifty rats were randomly assigned to 5 groups which were different in carbohydrate(25% of carbohydrate) and fiber(5% w/w) sources. The carbohydrate(CHO) sources of each group were comstarch(control group, 100% of CHO), fructose with cellulose(F), fructose with guar gum(FG), sucrose with cellulose(S), and sucrose with guar gum(SG). Each group was fed exterimental diet for 4 weeks. We measured food intake, body weight gain, adipose tissues weight and organs weight. We conducted oral glucose tolerance test(OGTT) and measured plasma insulin concentration to examine carbohydrate metabolism. To evaluate lipid metabolism, we measured the lipid profile of plasma, liver and feces. Food intake and weight gain of FG or SG groups tended to be less than those of F or S groups. Perirenal and epididymal fat pad weights of SG group were significantly lower than those of S group and those of FG group tended to be lower than those of F group. In OGTT, blood glucose values of F or S groups were significantly higher than those of C group, and FG or SG groups tended to be lower than those of F or S groups during the experimental time. The area under the curve(AUC) of C group was significantly highest among the groups, AUC and plasma insulin concentration of FG or SG groups tended to be lower than those of F or S groups. Plasma and hepatic triglyceride (TG) of FG and SG groups were significantly lower than those of F and S groups, plasma and hepatic total lipid(TL) and total cholesterol(TC) of FG and SG groups tended to be lower than those of F and S groups. Fecal TL, TG and TC of FG or SG groups tended to be higher than those of F and S groups. In conclusion, intake of guar gum should improve carbohydrate and lipid metabolism in partial substitution of fructose or sucrose for cornstarch in GK rats.

• Composites Research
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• v.37 no.3
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• pp.219-225
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• 2024

It is essential to develop a light-weight, high-performance structure for the deployable reflector antenna, which is the payload of a reconnaissance satellite, considering launch and orbital operation performance. Among them, the composite main reflector is a key component that constitutes a deployable reflector antenna. In particular, the development of a high-performance main reflector is required to acquire high-quality satellite images after agile attitude control maneuvers during satellite missions. To develop main reflector, the initial design of the main reflector was confirmed considering the structural performance according to the laminate stacking design and material properties of the composite main reflector that constitutes the deployable reflector antenna. Based on the initial design, four types of composite main reflectors were manufactured with the variable for manufacturing process. As variables for manufacturing process, the curing process of the composite structure, the application of adhesive film between the carbon fiber composite sheet and the honeycomb core, and the venting path inside the sandwich composite were selected. After manufacture main reflector, weight measurement, non-destructive testing(NDT), surface error measurement, and modal test were performed on the four types of main reflectors produced. By selecting a manufacturing process that does not apply adhesive film and includes venting path, for a composite main reflector with light weight and structural performance, we developed and verified a main reflector that can be applied to the SAR(Synthetic Aperture Rader) satellite.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.5
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• pp.89-98
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• 2007

This study investigates the deformation behavior, related to debonding failure, of adhesion and repairing-strengthening materials of RC construction. A strain-stress curve shows that when the stress of specimens reached the highest and then fails, the strain value of cement mortar is $2.0{\times}10^{-3}$, while concrete was indicated at around $1.3{\times}10^{-3}$, epoxy resins are $0.8{\times}10^{-3}$, polymer mortar is $2.5{\times}10^{-3}$, steel plate is $2.5{\times}10^{-3}$, and carbon bar was $9.1{\times}10^{-3}$, respectively. For a thermal expansion coefficient with temperature variation, those basis materials, cement mortar and concrete, exhibited around $10{\mu}{\varepsilon}/{^{\circ}C}$, but adhesive materials, such as epoxy resins and polymer mortar, were $41{\sim}54{\mu}{\varepsilon}/{^{\circ}C}$ and $-0.5{\sim}0.7{\mu}{\varepsilon}/{^{\circ}C}$, respectively. In the case of steel plate is similar to basic materials but carbon fiber is indicates at $-1.7{\mu}{\varepsilon}/{^{\circ}C}$, which is the lowest value. Especially, between basic and adhesive materials, the thermal expansion coefficient was highly different. Although the coefficient depends on the type of epoxy resins, it is clear that the epoxy resins are susceptible to be debonded in nature, when the difference of environmental temperature varies more than $20{\sim}35{^{\circ}C}$.

• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.535-563
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• 1993

New techniques for regenerating the destructed periodontal tissue have been studied for many years. Current acceptable methods of promoting periodontal regeneration alre basis of removal of diseased soft tissue, root treatment, guided tissue regeneration, graft materials, biological mediators. Platelet-derived growth factor (PDGF) is one of polypeptide growth factor. PDGF have been reported as a biological mediator which regulate activities of wound healing progress including cell proliferation, migration, and metabolism. The purposes of this study is to evaluate the possibility of using the PDGF as a regeneration promoting agent for furcation involvement defect. Eight adult mongrel dogs were used in this experiment. The dogs were anesthetized with Pentobarbital Sodium (25-30 mg/kg of body weight, Tokyo chemical Co., Japan) and conventional periodontal prophylaxis were performed with ultrasonic scaler. With intrasulcular and crestal incision, mucoperiosteal flap was elevated. Following decortication with 1/2 high speed round bur, degree III furcation defect was made on mandibular second(P2) and fourth(P4) premolar. For the basic treatment of root surface, fully saturated citric acid was applied on the exposed root surface for 3 minutes. On the right P4 20ug of human recombinant PDGF-BB dissolved in acetic acid was applied with polypropylene autopipette. On the left P2 and right P2 PDGF-BB was applied after insertion of ${\beta}-Tricalcium$ phosphate(TCP) and collagen (Collatape) respectively. Left mandibular P4 was used as control. Systemic antibiotics (Penicillin-G benzathine and penicillin-G procaine, 1 ml per 10-25 1bs body weight) were administrated intramuscular for 2 weeks after surgery. Irrigation with 0.1% Chlorhexidine Gluconate around operated sites was performed during the whole experimental period except one day immediate after surgery. Soft diets were fed through the whole experiment period. After 2, 4, 8, 12 weeks, the animals were sacrificed by perfusion technique. Tissue block was excised including the tooth and prepared for light microscope with H-E staining. At 2 weeks after surgery, therer were rapid osteogenesis phenomenon on the defected area of the PDGF only treated group and early trabeculation pattern was made with new osteoid tissue produced by activated osteoblast. Bone formation was almost completed to the fornix of furcation by 8 weeks after surgery. New cementum fromation was observed from 2 weeks after surgery, and the thickness was increased until 8 weeks with typical Sharpey’s fibers reembedded into new bone and cementum. In both PDGF-BB with TCP group and PDGF-BB with Collagen group, regeneration process including new bone and new cementum formation and the group especially in the early weeks. It might be thought that the migration of actively proliferating cells was prohibited by the graft materials. In conclusion, platelet-derived growth factor can promote rapid osteogenesis during early stage of periodontal tissue regeneration.

• Journal of the Mineralogical Society of Korea
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• v.6 no.2
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• pp.57-79
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• 1993

Chuncheon nephrite, which was formed by the polymetasomatic alteration of dolomitic marble, can be classified into pale green, green, dark green, and grey types on the basis of their occurrence, mineralogical and textural characteristics. The nephrites consist obiefly of fibrous or hairlike(length/width ratio>10) cryptocrystalline(crystal width < $2{\mu}m$) tremolite, and include less amounts of micro-crystalline diopside, calcite, clinochlore, and sphene as impurities. The oriented and rather curved crystal aggregate, of nephritic tremolite are densely interwoven, resulting in a massive-fibrous texture which may explain the characteristic toughness of nephritic jade. The characteristic greenish color of the nephrite may be preferably related to Fe rather than Cr and Ni. However, the variation of color and tint in the Chuncheon nephrite also depends on the mineralogical and textural differences such as crystallinity, texture, and impurities. The chemical composition of the nephritic tremolite is not stoichiometric and rather dispersed especially in the abundances of Al, Mg, and Ca. Al content and Mg/Ca ratio for the nephritic tremolite are slightly increased with deepening in greenish color of the nephrite. Fe content in the nephritic tremolite is generally very low, but comparatively richer in the dark green nephrite. In nephritic tremolite, wide-chain pyriboles are irregularly intervened between normal double chains, forming a chain-width disorder. Most nephritic tremolites in the Chuncheon nephrite show various type of chain-width defects such as triple chain(jimthompsonite), quintuple chain (chesterite), or sometimes quadruple chain in HRTEM observations. The degree of chain-width disorder in the nephritic tremolite tends to increase with deepening in greenish color. Triple chain is the most common type, and quadruple chain is rarely observed only in the grey nephrite. The presence of pyribole structure in the nephritic tremolite is closely related to the increase of Al content and Mg/Ca ratio, a rather dispersive chemical composition, a decrease of relative intensity in (001) XRD reflection, and an increase in b axis dimension of unit cell. In addition, the degree and variation of chain-width disorder with nephrite types may support that an increase of metastability was formed by a rapid diffusion of Mg-rich fluid during the nephrite formation.

• The Korean Journal of Pharmacology
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• v.26 no.2
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• pp.193-207
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• 1990

Transforming growth factor ${\beta}(TGF-{\beta})$ is a multifunctional polypeptide with diverse effects on the proliferation, differentiation and other functions in many cell types. $TGF-{\beta}$ is highly abundant in bone matrix and induces divergent responses in many aspects of bone cell metabolism . Several lines of investigation indicate that matrix-associated $TGF-{\beta}$ is the products of bone cells themselves. However, exact bone cell type reponsible for the production of $TGF-{\beta}$ is still in controversy, The present study was undertaken to determine the cellular origin of matrix-associated $TGF-{\beta}$ and to assess how different bone cells respond to $TGF-{\beta}$. As a prerequisite for this, 5 bone cell populations of distinct phenotype were isolated from fetal calvaria with sequential enzyme digestion protocol and biochemical characterization. Calvarial cell populations released in early stage showed fibroblastic features whereas populations relesed later was enriched with osteoblast-like cell as judged by their acid and alkaline phosphatase activities, cAMP responsiveness to parathyroid hormone, calcitonin and prostaglandin $E_2$ and collagen synthesis rate. By polyacylamide gel and immunoblot analysis of bone and calvarial cell extracts, presence of $TGF-{\beta}$ in bone tissues and production of $TGF-{\beta}$ by bone cells were confirmed again. Subsequent analysis of calvarial cell extracts prepared as individual population revealed that all calvarial cell populations synthesize $TGF-{\beta}$. Exogenously added $TGF-{\beta}$ induced biphasic response upon bone cell proliferation under serum-free condition. In osteoblastic cell populations, it was stimulatory whereas inhibitory in fibroblastic cell populations. In contrast, collagen and noncollagen protein synthesis of all calvarial cell populations were stimulated by $TGF-{\beta}$. Enhancement of protein synthesis was found to be more general rather than specific for collagen synthesis. In addition, effects of $TGF-{\beta}$ on protein synthesis were independent to its effects on cell proliferation. In summary, production of $TGF-{\beta}$ by bone cells and differential actions on various cell populations observed in this study suggest that $TGF-{\beta}$ may play an important role in the regulation of bone metabolism by modulating the specific cellular functions in autocrine and paracrine fashion.

• The Journal of the Korean bone and joint tumor society
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• v.19 no.2
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• pp.56-63
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• 2013

Purpose: This study was performed to evaluate the efficiency of demineralized bone matrix (DBM, Genesis$^{(R)}$) used for bone defect after operative traetment of benign bone tumors by clinical and radiological methods. Materials and Methods: DBM was used to treat bone defect after operative treatment of benign tumor from February 2012 to May 2013. Total 25 benign bone tumor cases (15 males, and 10 females) with mean age of 30.3 were studied. The diagnoses were solitary bone cyst in 9 cases, non ossifying fibroma in 5, fibrous dysplasia in 5, aneurysmal bone cyst in 3 and enchondroma in 3. In categorization by location of tumor, there were 5 cases of distal femur, 4 of proximal tibia, 3 of proximal femur, 3 of proximal humerus, 3 of phalanx, 2 of distal radius, 2 of hip bone, 2 of calcaneus, and 1 of scapula. Autogenous bone was used with DBM in 6 cases, and only DBM used in 19 cases. Mean periods of follow up were 8.7 months (range: 6 to 14 months). Amount of graft resorption and bone formation was observed with compare of post operation radiograph and the difference was shown by percentage. Resorption level was measured by DBM level which could be observed from simple x-ray, and bone formation level by bone trabecular formation level at impaired site. Results: Twenty three cases of total 25 cases showed bone union. In the 23 cases, more than 98% DBM resorption was observed after mean 4.3 months, and more than 98% bone formation was observed after mean 6.9 months. Lesser bone defect sizes showed faster bone formation and it was statistically significant (p=0.036). But other comparative studies on other factors such as, sex, age of patients and combination of autogenous bone were no statistically significant differences in graft resorption and bone formation. And there was no significant complication in periods of follow-up. Conclusion: Demineralized Bone Matrix (Genesis$^{(R)}$) is thought to be useful treatment for bone defect after operative treatment of benign bone tumor, however longer follow-up periods appears to be needed.