• Carbon letters
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• 제3권1호
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• pp.13-16
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• 2002

The modification of coal-tar pitch has been carried out by heat treatment of pitch at different temperatures in the range ($300^{\circ}-400^{\circ}C$) for different times (2-5 hrs) in air and nitrogen. The pitch heat treated in air at lower temperature ($300^{\circ}C$) exhibit increase in softening point by $20^{\circ}C$ as compared to only $2^{\circ}C$ when treated in nitrogen. The changes are faster in air than in pure nitrogen. Pitch as such as well as after heat treatment were further treated with metal complexes by solution route. Silver intake has been found to increase from 0.5 to 0.8 % in nitrogen treated pitch while the uptake is found to decrease for pitches treated in air at $350^{\circ}C$ for 5 hrs. Experiments have also been made to incorporate silver into PAN and PAN-ox fibers through solution route. The metal intake has been found to be more in PAN-ox fibers than in PAN as such. Metal loaded carbon composites have been made by using metal loaded fibers as well as cokes. These composites as such exhibit higher surface oxygen complexes but decrease after activation.

• 복식
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• 제21권
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• pp.207-218
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• 1993

The desire of our contempories who wish to recover humanities fading away and get back recover humanities fading away and get back to the nature is emerging as a main theme of the fashion today the decade of facing 21st century. The prevalence of naturalness-ecology ru-ral peasant look-and ethnic look shows the tendency mentioned above. Kenzo Takada' works which exhibit this naturalness and ethnic look were picked and investigated. The objective of this research is to study the beauty of form and internal and investi-gate in what form the naturaless and Ethnic look in Kenzo's work. The result were as followings : <1> Draped form are mainly used as form and they are made neglecting the body line by straight-cut and provide the wearer ease and freedom of movements <2> As for the color fantastic original colors (red, blue, etc) and natural colors are used. And Strong color contrast is seen. In ethnic look original colors(red, blue, etc.) natural colors and ethnic colors are used. <3> As for the fabric Cotton neat skilk and wool etc are used mainly and use of such natural fibers represents the return to the natural well. <4> As for ornament natural things-straw hat flower feather pebble, shell-are used and exhibit natural feelings strongly. For the ethnic look ornaments representing each country's ethnic atmos-phere by hat scarf and neckcloth made of natural fibers. <5> As for naturalness Flower deer butter-fly leopard and plant etc, are used as motif. As for ethnic look flower geometric motif are used.

• Natural Product Sciences
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• 제10권1호
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• pp.35-39
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• 2004

Aldose reductase (AR), the key enzyme of the polyol pathway, is known to play important roles in the diabetic complications. The inhibitors of AR, therefore, would be potential agents for the prevention of diabetic complications. In order to clarify the structural requirements of flavonoids for aldose reductase inhibitory activity, thirty flavonoids were examined. Among the thirty flavonoids, flavonols such as quercetin (5), reyneutrin (7), quercitrin (9), isoquercitrin (11), and avicularin (14) were found to exhibit much stronger AR inhibition. Lonicerin (10), amentoflavone (27) and sophoraflavanone B (30) were also showed strong inhibitory activity. Especially, quercitrin and reyneutrin exhibited the most inhibitory potency on rat lens (RL) AR. The results suggested that flavonol having the 7-hydroxyl and/or catechol moiety at the B ring exhibit strong activity. In addition, flavonols having 3-O-monosaccharide also showed stronger inhibition than free flavonols at the 3-position. These results suggested that quercitrin and reyneutrin are attributed to be the promising compounds for the prevention and/or treatment of diabetic complications.

• 대한핵의학회지
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• 제36권1호
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• pp.8-18
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• 2002

Early and accurate diagnosis of tumors using positron omission tomography (PET) has been the focus of considerable interest due to its high metastasis and mortality rates at late detection. PET radiopharmaceuticals-which exhibit a high tumor-to-background uptake ratio, and appropriate metabolic characteristics, and pharmacokinetics-are attractive tools for tumor imaging. Tumor imaging by these radiopharmaceuticals are based on metabolic and receptor imaging. The former is based on accelerated metabolism in tumor tissue compared to normal tissue and the rate roughly corresponding to the rate of growth of tumors. Radiopharmaceuticals for this purpose include radiolabeled sugars, amino acids, and nucleosides which detect increased glucose utilization, protein synthesis, and DNA synthesis, respectively. Tumor receptor imaging is based on the proliferation of tumor cells regulated by many hormones and growth factors, which bind to the corresponding receptors and exhibit the biological responses Radiopharmaceuticals used to image the tumor receptor systems may be ligands for the specific receptors and antibodies for the growth factor receptors. Some antitumor agents have been labeled with radionuclides and used to study in vivo biodistribution and pharmacokinetics in humans. This overview describes typical PET radiopharmaceuticals used for tumor imaging based on their uptake mechanisms.

• Asian Pacific Journal of Cancer Prevention
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• 제15권2호
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• pp.917-923
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• 2014

Chondrosarcomas are malignant cartilage-forming tumors of bone which exhibit resistance to both chemotherapy and radiation treatment. miRNAs have been well demonstrated to regulate gene expression and play essential roles in a variety of biological processes, including proliferation, differentiation, migration, cell cycling and apoptosis. In this study, we obtained evidence that miR-100 acts as a tumor suppressor in human chondrosarcomas. Interestingly, cisplatin resistant chondrosarcoma cells exhibit decreased expression of miR-100 compared with parental cells. In addition, we identified mTOR as a direct target of miR-100. Overexpression of miR-100 complementary pairs to the 3' untranslated region (UTR) of mTOR, resulted in sensitization of cisplatin resistant cells to cisplatin. Moreover, recovery of the mTOR pathway by overexpression of S6K desensitized the chondrosarcoma cells to cisplatin, suggesting the miR-100-mediated sensitization to cisplatin dependent on inhibition of mTOR. In summary, the present studies highlight miR-100 as a tumor suppressor in chondrosarcoma contributing to anti-chemoresistance. Overexpression of miR-100 might be exploited as a therapeutic strategy along with cisplatin-based combined chemotherapy for the treatment of clinical chondrosarcoma patients.

• 대한교통학회지
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• 제14권2호
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• pp.157-172
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• 1996

The long-existed licence system which has acted as one of the strong barriers to entry in the ocean shipping market in Korea is supposed to repeal in the near future. As a result, competition among the different sizes of firms which are operating under regional shield by means of the licence will be intensified. The main objective of this paper is to estimate the degree of economies of scale and economies of density for various firm sizes. For the successful estimation of economies scale and economies of density, translog cost models are developed and estimated through SURE technique which was suggested by Zeller (1963). The major findings are as follows ; All shipping firms in the sample exhibit economies of scale and density. Even small size shipping firms under licence system, they show substantial economies of scale contrary to the wide-known idea that small-size firms are subject to diseconomies of scale. For the ranked firm sizes according to owned deadweight tons, the degree of economies of scale decreases as the firm sizes are larger and larger. The degree of economies of density moderately declines from the smallest to the firm size of 30-60 thousand deadweight tons and sharply rise thereafter. And the large shipping firms with over half-million deadweight tons exhibit high economies density compared to other sizes of firm. If follows that the larger firms have great advantage in competition if the licence system is abolished.

• 한국재료학회지
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• 제30권3호
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• pp.105-110
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• 2020

Cu/PET composite films are widely used in a variety of wearable electronics. Lifetime of the electronics is determined by adhesion between the Cu film and the PET substrate. The formation of an anisotropic nanostructure on the PET surface by surface modification can enhance Cu/PET interfacial adhesion. The shape and size of the anisotropic nanostructures of the PET surface can be controlled by varying the surface modification conditions. In this work, the effect of Cu/PET interface nanostructures on the failure mechanism of a Cu/PET flexible composite film is studied. From observation of the morphologies of the anisotropic nanostructures on plasma-treated PET surfaces, and cross-sections and surfaces of the fractured specimens, the Cu/PET interface area and nanostructure width are analyzed and the failure mechanism of the Cu/PET film is investigated. It is found that the failure mechanism of the Cu/PET flexible composite film depends on the shape and size of the plasmatreated PET surface nanostructures. Cu/PET interface nanostructures with maximal peel strength exhibit multiple craze-crack propagation behavior, while smaller or larger interface nanostructures exhibit single-path craze-crack propagation behavior.

• 청정기술
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• 제17권3호
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• pp.238-243
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• 2011

본 연구에서는 폴리우레탄을 위한 친환경 폴리올 합성을 위하여 피마자유 기반의 폴리올을 합성하였다. 피마자유의 2차 알콜에 다른 촉매 없이 무수말레산을 이용하여 카르복실기를 도입하고, 이를 1차 알콜로 전환하기 위하여 아미노알콜($H_2N$-R-OH) 유도체를 반응시켜 친환경 폴리올을 제조하였다. 다양한 비율의 피마자유와 무수말레산의 반응이 시험 되었으며, 전체 반응은 상대적으로 낮은 공정온도와 무촉매 반응을 기반으로 수행되었다. 긴 곁가지가 도입되어 유동성을 가지고 있는 피마자유 기반의 천연폴리올이 기존의 합성폴리올과 가장 우수한 상용성을 나타내었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.112-112
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• 2013

Well-defined surfaces of single-crystalline solid materials are starting points of self-organizationof nanostructures and chemical reactions controlled in nanoscale. Although highly ordered atomicarrangement can be obtained on semiconductor surfaces, they can be maintained only in vacuumand not in air or in aqueous environment. Since single-crystalline metal oxide surfaces arechemically stable and no further oxidation occurs, their atomic structures can be utilized fornanofabrication in liquid processes, nanoelectrochemistry and nanobiotechnology. Sapphire is oneof the most stable metal oxides and its crystalline quality is excellent, as can be applied to electronicdevices that require ultralow defect densities. We recently found that chemical phase separationoccurs on sapphire surfaces by annealing processes and the formed nanodomains exhibit specificproperties in air and in water [1,2]. In our experiments, highly selective and controllable adsorptionof various protein molecules is observed on the phase-separated surfaces though the materials andcrystallographic orientations are identical [3,4]. Planar lipid bilayers supported on thephase-separated sapphire surface also exhibit a specific formation site selectivity [5]. Chemicalnanodomains appear on other metal-oxide surfaces, such as well-ordered titania surfaces. Wedemonstrate that surface chemistry of the nanodomains can be characterized in aqueousenvironment using atomic force microscopy equipped with colloidal tips and then show adsorptionand desorption behaviors of various proteins on the phase-separated surfaces.

• 멤브레인
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• 제25권2호
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• pp.171-179
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• 2015

과불소계 술폰화 이오노머(perfluorinated sulfonic acid ionomers; PFSAs)는 뛰어난 수소이온전도성과 높은 내화학성으로 인해 고분자 전해질 연료전지(polymer electrolyte fuel cells)용 고체전해질로 널리 사용되고 있다. 그러나 PFSA 전해질은 가습-건조조건에서 연료전지가 구동에 따라 반복적인 팽윤-수축으로 인해 전극층이 전해질로부터 탈리되어 전기화학적 수명특성이 감소되는 문제점을 가지고 있다. 본 연구에서는 다공성 PTFE support film의 기공특성에 대한 이해를 바탕으로 기공구조 내 나피온 이오노머를 함침시키는 강화막을 제조하였고, 기본특성을 평가하였다. 제조된 강화막은 매우 높은 수소이온전도도(${\sim}~0.5S\;cm^{-1}@90^{\circ}C$ in liquid water)를 나타내었다.