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- 저자 : ( Kyeong-ok Choi ) (검색결과 292 건)
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Shape- and size-controlled synthesis of noble metal nanoparticles
Choi, Kyeong Woo,Kim, Do Youb,Ye, Seong Ji,Park, O Ok Techno-Press 2014 Advances in materials research Vol.3 No.4
Noble metal nanoparticles (mainly Au, Ag, Pt and Pd) have received enormous attention owing to their unique and fascinating properties. In the past decades, many researchers have reported methods to control the shape and the size of these noble metal nanoparticles. They have consequently demonstrated outstanding and tunable properties and thus enabled a variety of applications such as surface plasmonics, photonics, diagnostics, sensing, energy storage and catalysis. This paper focuses on the recent advances in the solution-phase synthesis of shape- and size-controlled noble metal nanoparticles. The strategies and protocols for the synthesis of the noble metal nanoparticles are introduced with discussion of growth mechanisms and important parameters, to present the general criteria needed for producing desirable shapes and sizes. This paper reviews their remarkable properties as well as their shape- and size- dependence providing insights on the manipulation of shape and size of metal nanoparticles, necessary for appropriate applications. Finally, several applications using the shape- and size-controlled noble metal nanoparticles are highlighted.
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Ok, Seong Ho,Bae, Sung Il,Kwon, Seong Chun,Park, Jung Chul,Kim, Woo Chan,Park, Kyeong Eon,Shin, Il Woo,Lee, Heon Keun,Chung, Young Kyun,Choi, Mun Jeoung,Sohn, Ju Tae The Korean Pain Society 2014 The Korean Journal of Pain Vol.27 No.3
Background: A toxic dose of bupivacaine produces vasodilation in isolated aortas. The goal of this in vitro study was to investigate the cellular mechanism associated with bupivacaine-induced vasodilation in isolated endothelium-denuded rat aortas precontracted with phenylephrine. Methods: Isolated endothelium-denuded rat aortas were suspended for isometric tension recordings. The effects of nifedipine, verapamil, iberiotoxin, 4-aminopyridine, barium chloride, and glibenclamide on bupivacaine concentration-response curves were assessed in endothelium-denuded aortas precontracted with phenylephrine. The effect of phenylephrine and KCl used for precontraction on bupivacaine-induced concentration-response curves was assessed. The effects of verapamil on phenylephrine concentration-response curves were assessed. The effects of bupivacaine on the intracellular calcium concentration ($[Ca^{2+}]_i$) and tension in aortas precontracted with phenylephrine were measured simultaneously with the acetoxymethyl ester of a fura-2-loaded aortic strip. Results: Pretreatment with potassium channel inhibitors had no effect on bupivacaine-induced relaxation in the endothelium-denuded aortas precontracted with phenylephrine, whereas verapamil or nifedipine attenuated bupivacaine-induced relaxation. The magnitude of the bupivacaine-induced relaxation was enhanced in the 100mM KCl-induced precontracted aortas compared with the phenylephrine-induced precontracted aortas. Verapamil attenuated the phenylephrine-induced contraction. The magnitude of the bupivacaine-induced relaxation was higher than that of the bupivacaine-induced $[Ca^{2+}]_i$ decrease in the aortas precontracted with phenylephrine. Conclusions: Taken together, these results suggest that toxic-dose bupivacaine-induced vasodilation appears to be mediated by decreased calcium sensitization in endothelium-denuded aortas precontracted with phenylephrine. In addition, potassium channel inhibitors had no effect on bupivacaine-induced relaxation. Toxic-dose bupivacaine-induced vasodilation may be partially associated with the inhibitory effect of voltage-operated calcium channels.
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Kyeong-Mee Park,Man-Hee Rhee,Han-Jae Shin,Yong-Bum Song,Hak-Chul Hyun,Ki-Hyun Park,Hyun-Jeong Cho,Sun-A Choi,Hyo-Chan Kang,Kyoung Jin Kim,Hyeong-Soo Kim,Hee-Jin Kang,Woo-Jeong Ok,Dong-Ha Lee,Hwa-Jin P 고려인삼학회 2008 Journal of Ginseng Research Vol.32 No.2
In this study, we have investigated the effect of panaxatriol (PT) on phosphoinositides (PIS) breakdown and Ca<SUP>2+</SUP>-elevation in thrombin-induced platelet aggregation. Thrombin (5U/ml), a potent platelet agonist which activates phospholipase Cβ via protease activated receptor (PAR), hydrolyzed PIS in platelet membrane. The phosphatidylinositol 4, 5-bisphosphate (PIP₂) was hydrolyzed after 10 sec of the thrombin-stimulation, and both the phosphatidylinositol 4-monophosphate (PIP) and phosphatidylinositol (PI) were brokendown after 30 sec of the thrombin-stimulation. However, PT inhibited the thrombin-stimulated hydrolysis of PIP₂, PIP, and PI. On the other hand, thrombin increased the level of phosphatidic acid (PA) which is phosphorylated from diacylglycerol (DG) generated by PIS-hydrolysis. However, PT inhibited the thrombin-increased PA level non-significantly. Thrombin increased cytosolic free Ca<SUP>2+</SUP>[Ca<SUP>2+</SUP>]i) up to 72% as compared with control (30.8±0.9 nM) in intact platelet. However, PT (100 ㎍/ml) inhibited the thrombin-elevated [Ca<SUP>2+</SUP>]i to 100%. These results suggest that PT may have a beneficial effect on platelet aggregation-mediated thrombotic disease by inhibiting thrombin-induced platelet aggregation via suppression of the [Ca<SUP>2+</SUP>]i level and PIS breakdown.
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Kyeong Ok Choi,이인애,Sae-Yeol-Rim Paik,김동은,Jung Dae Lim,강위수,고상훈 한국식품영양과학회 2012 Journal of medicinal food Vol.15 No.10
The root of Angelica gigas (Korean angelica) is traditionally used to treat women's ailments that are caused by an impairment of menstrual blood flow and cycle irregularities. This study evaluated the effect particle size of Korean angelica powder on its efficacy for treating estrogen-related symptoms of menopause. Initially, Korean angelica roots were pulverized into ultrafine powder, and orally administered to the rats at a concentration of 500 mg/kg body weight for 8 weeks. The effects of Korean angelica powder particle size on extraction yield, contents of bioactive compounds (decursin and decursinol angelate), levels of serum ovarian hormones (estradiol and progesterone), reproductive hormones (luteinizing hormone and follicle-stimulating hormone), and experimental osteoporosis parameters (mineral density, strength, and histological features) were determined. A significant increase (fivefold) in the contents of decursin and decursinol angelate in the extract of the ultrafine Korean angelica powder was observed compared to coarse Korean angelica powder. Rats were divided into sham-operated or ovariectomized (OVX) groups that were fed coarse (CRS) or ultrafine (UF) ground Korean angelica root. The serum levels of estradiol in the OVX_UF group were 19.2% and 54.1% higher than that of OVX_CRS group. Serum bone-alkaline phosphatase/total-alkaline phosphatase index in the OVX_UF group was half that of the OVX_CRS group. In addition, less trabecular bone loss and thick cortical areas were observed in rats administered ultrafine powder. Therefore, ultrafine grinding may enhance the bioactivity of herbal medicines and be especially useful when their extracted forms lose bioactivity during processing, storage, and oral intake.
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Regional Realtime Ocean Tide and Storm-surge Simulation for the South China Sea
Kyeong Ok Kim(김경옥),Byung Ho Choi(최병호),Han Soo Lee(이한수),Jin-Hee Yuk(육진희) 한국해안해양공학회 2018 한국해안해양공학회 논문집 Vol.30 No.2
남중국해는 심해 분지, 대륙 붕단, 얕은 대륙붕, 많은 해협, 복잡한 수심 특징을 가진 전형적인 연안 영해이다. 본 연구에서는, 비구조 격자 기반으로 대상 해역을 상세하게 해상할 수 있으며, 개방경계에 조석을, 해표면에 기상자료를 입력하여 조석 및 폭풍해일을 모의할 수 있는 수치 모델을 구축하여 남중국해의 조석 특성과 전파 양상을 조사하고, 태풍에 의한 폭풍해일을 재현하였다. 태풍에 의한 폭풍해일 모의는, 2013년에 필리핀에 막대한 피해를 초래하였던 태풍 하이옌에 대해서 수행하였다. 관측치 및 선행 연구의 조석 분포와의 비교 결과, 4개의 주요 분조의 진폭과 위상은 대체적으로 잘 모의되었다. 선행 연구들에 따르면, 당 해역은 모델을 이용하여 조석을 예측하기가 어렵다고 보고되고 있는데, 이 점을 감안한다면 본 연구에서 예측한 조석은 허용 범위에 있다고 생각된다. 본 연구에서 수행한 자유 진동 모드 실험을 통해서 남중국해가 일주조 조석이 우세한 이유를 알 수 있었으며, 조석 잔차류(tidal residual current) 및 총에너지 소실(total energy dissipation) 산정을 통해서 조석 및 퇴적환경을 파악하였다. 본 연구에서 구축한 모델을 이용하여 태풍 하이옌에 의한 폭풍해일을 타당하게 모의하였으며, 모델 검증 및 조석 환경 규명을 통하여 남중국해의 지역 실시간 순압 조석/수위 예측 시스템을 구축하였다. The South China Sea (SCS) is a typical marginal sea characterized with the deep basin, shelf break, shallow shelf, many straits, and complex bathymetry. This study investigated the tidal characteristics and propagation, and reproduced typhoon-induced storm surge in this region using the regional real-time tide-surge model, which was based on the unstructured grid, resolving in detail the region of interest and forced by tide at the open boundary and by wind and air pressure at the surface. Typhoon Haiyan, which occurred in 2013 and caused great damage in the Philippines, was chosen as a case study to simulate typhoon"s impact. Amplitudes and phases of four major constituents were reproduced reasonably in general, and the tidal distributions of four constituents were similar to the previous studies. The modelled tide seemed to be within the acceptable levels, considering it was difficult to reproduce the tide in this region based on the previous studies. The free oscillation experiment results described well the feature of tide that the diurnal tide is prevailing in the SCS. The tidal residual current and total energy dissipation were discussed to understand the tidal and sedimentary environments. The storm-surge caused by typhoon Haiyan was reasonably simulated using this modeling system. This study established the regional real-time barotropic tide/water level prediction system for the South China Sea including the seas around the Philippines through the validation of the model and the understanding of tidal characteristics.
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International Marriage Brokerage and Human Rights of Immigrant Women
( Kyeong-ok Choi ) 건국대학교 이주사회통합연구소 2017 Journal of Migration and Social Integration (JMSI) Vol.2 No.2
Immigration may be defined to be an act of moving life base by reason of profession, marriage or some other choices to the places that have different culture, language, safety etc. Although such choice is followed by various dangers, nonetheless such immigration trend has been part of life in the globalized society. This thesis will cover subjects laying special stress on female marriage immigrants. In the meantime, the immigration problem cannot be viewed from simple domestic demographic side, but ratherly a horizen should also be opened from the point of globalized universal aspect of human right. Primarily, international marriage contains problems of language, culture, welfare, security, crime victim etc. Furthermore, problem of non-documented stay may arise in case that the immigrants has not acquired Korean citizenship yet due to the reasons like divorce etc. In America, president Obama gave an administrative order on November 20, 2014 in order to solve the problem for non-documented immigrants. The point of this administrative order contains “a purpose of stopping family separation by means of postponement of deportation but not giving amnesty to the non-documented immigrants” and it puts emphasis on that “as the amnesty belongs to the right of Federal Congress, it cannot be linked to any acquirement of permanent residency or citizenship, and also that immigration is extended to the filed of investment and technology at the same time with heightened security of border for prevention of entry by illegal immigration.” As such is the case, the significance of crossing the border in way of life gives rise to education problems for them and their offsprings including those like cultural, language and security problems. Therefore, this thesis will cover problems that may possibly even cause them to divorce due to unsatisfied marital life with husband, laying stess on female marriage immigrants, and in such case, problem of marriage mediation(II), protection countermeasure for female marriage immigrants(III), and problem of marriage and immigration(IV).
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