• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.1
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• pp.41-48
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• 2017

Fine polymeric fibers have been gaining interest from the energy harvesting/storage, tissue, and bioengineering industries because of advantages such as the small diameter, high porosity, permeability, and similarities to a natural extracellular matrix. Electrospinning is one of the most popular methods used to fabricate polymeric fibers because it is not as limited in regards to the materials selection, and it does not require expensive or complex equipment. However, electrospun fibers have a severe aerodynamic instability because the small diameter fibers are able to pass through the atmospheric layer when there is a high electric field. As a result, electrospun fibrous mats have serious difficulties with controlling its shape and geometric properties. In this study, a hybrid nano/microfibrous mat is presented that is fabricated using electrospinning with two different solvent-based PCL solutions. This provides control of the fiber diameter, mat porosity, and mechanical properties. Various hybrid fibrous mats were fabricated after an experimental investigation of the effects of solvent on fiber diameter. It was then demonstrated that the mechanical properties and porosity of the fabricated various hybrid mats could be successfully controlled.

• Nuclear Engineering and Technology
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• v.38 no.5
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• pp.399-404
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• 2006

Noninvasive molecular targeting in living subjects is highly demanded for better understanding of such diverse topics as the efficient delivery of drugs, genes, or radionuclides for the diagnosis or treatment of diseases. Progress in molecular biology, genetic engineering and polymer chemistry provides various tools to target molecules and cells in vivo. We used chitosan as a polymer, and $^{99m}Tc$ as a radionuclide. We developed $^{99m}Tc-galactosylated$ chitosan to target asialoglycoprotein receptors for nuclear imaging. We also developed $^{99m}Tc-HYNIC-chitosan-transferrin$ to target inflammatory cells, which was more effective than $^{67}Ga-citrate$ for imaging inflammatory lesions. For an effective delivery of molecules, a longer circulation time is needed. We found that around 10% PEGylation was most effective to prolong the circulation time of liposomes for nuclear imaging of $^{99m}Tc-HMPAO-labeled$ liposomes in rats. Using various characteristics of molecules, we can deliver drugs into targets more effectively. We found that $^{99m}Tc-labeled$ biodegradable pullulan-derivatives are retained in tumor tissue in response to extracellular ion-strength. For the trafficking of various cells or bacteria in an intact animal, we used optical imaging techniques or radiolabeled cells. We monitored tumor-targeting bacteria by bioluminescent imaging techniques, dentritic cells by radiolabeling and neuronal stem cells by sodium-iodide symporter reporter gene imaging. In summary, we introduced recent achievements of molecular nuclear imaging technologies in targeting receptors for hepatocyte or inflammatory cells and in trafficking bacterial, immune and stem cells using molecular nuclear imaging techniques.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.69-71
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• 2004

The proton therapy of radiation therapy methods using Bragg Peak which is proton beam's characteristic dose distribution can give a normal tissue lower dose than cancer, comparing with the former existing radiation therapy methods. For exact treatment and patient' safety, we need to know proton beam's position in body, but a proton beam completely stops at treatment region and proton beam's range is uncertainly made by the variety of organs having each different density, so we aren't able to find a proton beam' position by suitable methods yet. With Monte Carlo Computing Method, as a result that we had simulated prompt gamma detection system using correlation of proton beam's absorbed dose distribution about water and prompt gamma distribution by nuclear interaction occurred by collisions of proton and water's hydrogen atoms, we could confirm that a proton beam's position was able to detect by using simulated prompt gamma detection system in body on the real-time

• Environmental Analysis Health and Toxicology
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• v.29
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• pp.8.1-8.8
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• 2014

Objectives An ecofriendly alternative to chemical pesticides is bio-pesticides, which are derived from natural sources. The interest in bio-pesticides is based on the disadvantages associated with chemical pesticides. Methods We conducted acute toxicity assessments of camphor, a major component of bio-pesticides, by using Daphnia magna (D. magna) as well as assessed the morphological abnormalities that occurred in Danio rerio (D. rerio) embryos. Results The median effective concentration of camphor on D. magna after 48 hours was $395.0{\mu}M$, and the median lethal concentration on D. rerio embryos after 96 hours was $838.6{\mu}M$. The no observed effect concentration and predicted no effect concentration of camphor on D. magna, which was more sensitive than D. rerio, were calculated as $55.2{\mu}M$ and $3.95{\mu}M$, respectively. Morphological abnormalities in D. rerio embryos exposed to camphor increased over time. Coagulation, delayed hatching, yolk sac edema, pericardial edema, and pigmentation of embryos mainly appeared between 24 and 48 hours. Further, symptoms of scoliosis and head edema occurred after 72 hours. In addition, bent tails, ocular defects and collapsed symptoms of fertilized embryonic tissue were observed after 96 hours. Conclusions The camphor toxicity results suggest that continuous observations on the ecosystem are necessary to monitor toxicity in areas where biological pesticides containing camphor are sprayed.

• Journal of Biomedical Engineering Research
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• v.14 no.1
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• pp.51-62
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• 1993

An experimental study was performed for the preparation of living skin-equivalent by the using collagen gel contraction with human fibroblasts as neodermls and cultured human keratinocytes as neoderm is . The results were as follows ; 1) The rate of collagen gel contraction was dependent on the number of fibroblasts into the lattice and collagen contraction was progressed according to the increment of the number of the cells. 2) The rate of collagen gel contraction was progressed according to the decrement of the contraction of the collagen. 3) The rate of gel contraction was progressed according to the increment of serum concentration in the fixed concentration of the fibroblasts and collagen. 4) The lattice contraction was decreased according to the increment of the population doublings of the fibroblasts. 5) Macroscopically, the artificial dermis was gray white in color and tissue-like consistency and elas- ticity. 6) Microscopically, three dimensionally contracted artificial dermis showed more dense fibroblasts and its newly formed collagen fibrils in the matrix than one dimensionally contracted one. 7) Finally prepared skin-equivalent showed good attachment of living stratified keratinocytes to the dermal equivalent microscopically. It has been proposed that newly formed skin-equivalent is suitable for the graft of extensively and deeply burned patients. Shortening of the manufacturing period of skin-equivalent and development of conservation technique as a readily usable state are to be solved for our ongoing works.

• Korean Journal of Food Science and Technology
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• v.23 no.1
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• pp.6-14
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• 1991

Intramuscular lipid of longissimus dorsi muscle(white muscle), soleus muscle(red muscle) and cardiac muscle were autooxidized at $37^{\circ}C$ for 20 days, and the rancidity development and the effect of various factors on rancidity development were compared. Although the myoglobin content of red muscle was about 5 times as high as that of white muscle, the degree of autooxidation occurred in intramuscular lipid did not differ between red muscle and white muscle, when they had the same lipid content. Accordingly, it was suggested that the susceptibility of muscle tissues to lipid oxidation depends mainly on the lipid content of muscle tissue, regardless of muscle types. Lipid oxidation was not a major quality deterioration for dried-pork product, when it contained adequate amount of sodium nitrite and was air-tight vacuum-packed.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.369-377
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• 1998

Rotavirus is a major cause of severe gastroenteritis in young children and animals throughout the world. The VP7 of rotavirus is thought to induce the synthesis of neutralizing antibodies and to be responsible for determining viral serotypes. The cDNA coding for the VP7 capsid protein of human rotavirus, obtained from Korean patients (HRV-Y14), was cloned and its nucleotide sequence was determined. Comparative analysis of the nucleotide sequences between VP7 of Y14 and that of other foreign isolates showed $92.7~95.2\%$ homology to G1 serotypes (RV-4, KU, K8, WA), $74.2\%$ homolgy to G2 serotype HU-5, $76.4\%$ homology to G3 serotype SA-11, and $77.6\%$ homology to G4 serotype A01321. These data suggest that HRV-Y14 can be classified as a G1 serotype. cDNA coding for VP7 of HRV-YI4 was subcloned into the baculovirus vector and the VP7 glycoprotein was expressed in insect cells. The expressed proteins in Sf9 cell extract and tissue culture fluid were separated on SDS-PAGE, and Western blot analysis with monoclonal antibody raised against the synthetic peptide containing 21 amino acids within the VP7 conserved region was performed. The molecular weight of recombinant VP7 was estimated to be 36 kDa which is about the same size as the native VP7. Addition of tunicamycin in the culture media caused a reduction of the molecular weight of the recombinant VP7 indicating that the expressed protein was glycosylated.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.192-202
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• 2003

The wrinkles correspond to the most obvious expression of skin ageing and are manifested by changes on the organization and dermal structure. In the extracellular matrix, decreased quantities of collagens and glycosaminoglycans as well as a deterioration of the fibrillary network is noted, result in a reduction of dermal thickness. In addition, the activity of the collagenases increases in contrast to the synthesis of collagen fibers. Nor are cells spared during the aging process. We thus studied and compared the contractile capacity as well as the synthesis capacity of normal human fibroblasts and human fibroblasts obtained from biopsies of forehead wrinkles. The capacity of the fibroblasts to be adhered to the collagen network and to maintain a three-dimensional structure of dermis was studied on a model of equivalent dermis. The metabolic activity was studied by evaluating the capacities of synthesis of collagen I, main component of dermis. Human fibroblasts resulting from the forehead wrinkle contract less the gel of collagen than the normal human fibroblasts and present an activity of biosynthesis of collagen I less important than normal human fibroblasts. These results show that fibroblasts with aging present a deceleration of their metabolic activity and lose their capacity of adhesion to collagen fibers thus limiting the possibility of organizing the dermal tissue. We investigated the potential of an active ingredient able to compensate for the reduction of the metabolic activity and to restore the contractile capacity of fibroblasts obtained from forehead wrinkles. This effect was compared with a reference molecule: the vitamin C.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.10
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• pp.97-107
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• 2015

The initial X-ray images obtained from a digital X-ray machine have a wide data range and uneven brightness level than normal images. In particular, in Chest X-ray images, it is necessary to improve naturally all of the parts such as ribs, spine, tissue, etc. These X-ray images can not be improved enough from conventional image quality enhancement algorithms because their characteristics are different from ordinary images'. This paper proposes to eliminate unnecessary background from an input image and expand the histogram range of the image. Then, we adjust the weight per frequency band of the image for improvement of contrast and sharpness. Finally, jointly taking the advantages of global contrast enhancement and local contrast enhancement methods we obtain an improved X-ray image suitable for effective diagnosis in comparison with the existing methods. Experimental results show quantitatively that the proposed algorithm provides better X-ray images in terms of the discrete entropy and saturation than the previous works.

• Journal of Periodontal and Implant Science
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• v.33 no.1
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• pp.49-60
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• 2003

Several growth factors and polypeptides are not commonly yet used for regenerators of bone tissue or alveolar bone because of the insufficiency of studies on their side effects, genetic engineering for mass production and stability for clinical application. Recently, many herbal medicines, which have advantage of less side effects and possibility of long-term use, have been studied for their capacity and effects of anti-bacterial, antiinflammatory and regenerative potential of periodontal tissues. Morindae Radix, Cibotium Barometz (L.), Albizziae Cortex, Cistandhis Herba have been traditionally used as medicines for treatment of bone disease in Eastern medicine. The objective of the present study is to examine the ability of alkaline phosphatase (ALP) activity of human fetal osteoblast (hFOB1) when several natural medicines were supplemented. hFOB1 were cultured with Dulbecuo's Modified Eagle's Medium Nutrient Mixture F-12 HAM ( DMEM/F-12 1:1 Mixture, Sigma, USA) and negative control, dexamethasone (positive control), and each natural medicines for 3 days. And then ALP activity was measured by spectrophotometer for enzyme activity and Alizarin red S staining for morphometry. Among the natural medicines of this study, Morindae Radix, Cibotium Barometz (L.) and Cistanchis Herba induced higher activity of ALP synthesis than negative controls in all experimental group. Albizziae Cortex showed mild increases than negative control group. According to measurement of positively stained area, all of the natural medicines of this study increased compared to negative control. Especially, Cibotium Barometz (L.) and Cistanchis Herba showed statistical significance compared to negative control (p<0.05). These results indicate that Morindae Radix, Cibotium Barometz (L.), Albizziae Cortex, Cistandhis Herba have an inducing ability of ALP synthesis on osteoblast.