Starch 현탁수용액에서 Sodium CMC 및 Ethylene Glycol에 의한 Flow Mechanism변화에 관한 연구

윤재영,방정환,김응렬 漢陽大學校 基礎科學硏究所 1988 基礎科學論文集 Vol.7 No.-

15℃에서 44.4 wt.% Starch-H₂O 현탁액에 Sodium CMC와 ethylene glycol을 첨가시켜 매질의 종류에 따른 유동 성질의 변화를 Couette type rotational viscometer를 사용하여 조사하였다. 44.4 wt.% Starch-H₂O 현탁액의 경우에는 유동 성질이 dilatancy로 나타났고, 여기에 소량의 sodium CMC를 첨가했을 경우에는 그 유동 성질이 thixotropy로 바뀌었으며 그리고, 60wt.% ethylene glycol수용액을 매질로 사용했을 때에는 Newtonian 성질의 유동 곡선을 얻을 수 있었다. 이 때 dilatancy와 thixotropy의 유동 곡선들에 대해서는 Ree-Eyring 이론으로부터 유도되어진 dilatancy에 대한 Bang 등의 식과 thixotropy에 대한 Sohn 등의 식을 적용하여 유동 파라메타들을 구해보았으며, 매질의 종류에 따른 유동 성질의 변화를 입자 간에 형성되는 수소 결합과 관련지워 생각하여 보았다. We observed the change of the flow property by using the Couette type rotational viscometer adding small amount of sodium CMC and ethylene glycol in the 44.4wt.% starch-water suspension at 15℃. In the 44.4% starch-water suspension, the flow property became dilatancy, and when a small amount of sodium CMC was added the flow property was changed into thixotropy and when 60 wt.% ethylene glycol aqueous solution was used as medium, Newtonian flow curves were observed. In the flow curves of dilatancy and thixotropy, flow parameters were obtained applying Bang et al.'s formula of dilatancy and Sohn et al.'s formula of thixotropy derived from the Ree-Eyring theory and the changes of the flow properties with the components of flow system were explained in connection with hydrogen bond formation between the particles.

환경친화성 계면활성제를 이용한 어병균의 살균효과

최상원,정관용,오남희,김은영,방정환,김정우,여문환 한국환경과학회 2000 한국환경과학회지 Vol.9 No.5

The antibacterial effect amino acid-copper(Ⅱ) surfactant on fish pathogens was studied. Fish pathogens of Edwardsiella tarda, Vibrio anguillarum, Aeromonas hydrophila and Streptococcus sp. were selected, cultured in nutrient agar and adjusted at 2 × 10 exp (5)∼10 exp (6) CFU/㎖ in phosphate buffer saline before the addtion of amino acid-copper(Ⅱ) surfactant with different concentrations. All tested pathogens died within 1 hour with 1 ppm of amino acid-copper(Ⅱ) surfactant. In comparison with formalin and ET, amino acid-copper(Ⅱ) surfactnat was more effective in antibacterial capacity.

만성 심부전환자의 혈액에서 측정한 Tumor necrosis factor-α 및 Interleukin-6의 임상적 의의

김명구,김성구,박상호,한대희,강진환,변정득,심규혁,최병조,방덕원,온영근,현민수,권영주 순천향의학연구소 2001 Journal of Soonchunhyang Medical Science Vol.7 No.2

Background and objectives: Many conditions are responsible for the pathophysiology and progressive mechanisms of congestive heart failure. More recently, it has also become evidence that another class of biologycally activated molecules generically reffered to as cytokine these are also over expressed in congestive heart failure. Therefore, the purpose of this study was to measure concentrations of tumor necrosis factor-α(TNF-α), interleukin-6(IL-6) in mild to severe symptoms of heart failure and compare their values with those found in normal control and analysed correlation relationship between cytokine level, clinical findings and hemodynamic indicies. Subjects and Methodology: Levels of TNF-α and IL-6 were measured on pulmonary artery during cardiac catheterization in heart failure patients(n=32) and normal subjects(n=8) as well as physical examination and echocardiogram. Cytokines assay were performed on plasma using commercially available ELISA(Enazyme-Linked Immunosorbent Assay) kits. Results: Although the levels of TNF-α and IL-6 tend to increase in congestive heart failure group, the cytokines level was not made significantly statistical difference between congestive heart failure group and controls. When analyzing the correlation between the levels of PCWP(pulmonary capillary wedge pressure) and cytokines(TNF-α, IL-6), respectively, there were statistically significant correlation coefficient 0.32,(p<0.05), 0.39(p<0.01). The cytokine IL-6 and pressure of pulmonary artery were significant correlation.(correlation coefficient 0.36, p<0.02) More significantly, there was correlated with TNF-α and IL-6.(correlation coefficient 0.57, p<0.001) Conclusions: There was tended toward high concentration of TNF-α & IL-6 in congestive heart failure and significant difference for PCWP between TNF-α & IL-6, thus may be correlated with development and progression in congestive heart failure.

Effect of an Electric Field on the AC Electrical Treeing in Various Epoxy/Reactive Diluent Systems

Bang, Jeong-Hwan,Park, Jae-Jun The Korean Institute of Electrical and Electronic 2013 Transactions on Electrical and Electronic Material Vol.14 No.6

The effect of an electric field on the ac electrical treeing in various epoxy/reactive diluent systems was studied in a needle-plate electrode geometry. Diglycidyl ether of bisphenol A (DGEBA) type epoxy was used as a base resin, and 1,4-butanediol diglycidyl ether (BDGE) or polyglycol (PG) as a reactive diluent was introduced to the DGEBA system, in order to decrease the viscosity of the DGEBA epoxy system. BDGE was acted as a chain extender, and PG acted as a flexibilizer, after the curing reaction. To measure the treeing initiation time and the propagation rate, three constant alternating currents (ac) of 10, 13 and 15 kV/4.2 mm (60 Hz) were applied to the specimen, in a needle-plate electrode arrangement, at $30^{\circ}C$ of insulating oil bath. When 10 kV/4.2 mm (60 Hz) was applied, the treeing initiation time and the propagation rate in the DGEBA system were 356 min and $1.10{\times}10^{-3}$ mm/min, respectively, those in the DGEBA/BDGE system were 150 min and $1.14{\times}10^{-3}$ mm/min, respectively. Those in the DGEBA/PG system were 469 min and $1.05{\times}10^{-3}$ mm/min, respectively. As 15 kV/4.2 mm (60 Hz) was applied, the propagation rate in the DGEBA system was $5.41{\times}10^{-3}$ mm/min, and that in the DGEBA/PG system was $1.42{\times}10^{-3}$ mm/min. These values meant that PG could be used as a reactive diluent in the DGEBA system, without the deterioration of the insulation breakdown property.

A novel tissue culture method using 3D bioprinting of melanoma acquired from patient derived xenograft model

( Chul Hwan Bang ),( Yun-mi Jeong ),( Hae Eun Park ),( Jin Woo Park ),( Ga Hee Jeong ),( Min Ji Park ),( Yunjae Lee ),( Songwan Jin ),( Ji Hyun Lee ) 대한피부과학회 2020 대한피부과학회 학술발표대회집 Vol.72 No.1

Background: Although advances have been made in in vitro technologies of culturing cells, there is limitation that microenvironment in which cells are cultured is not same as that in human skin, making it difficult to predict therapeutic response. Using 3D bioprinting in in vitro melanoma tissue culture would provide environments more similar to the physiologic conditions, realizing personalized medicine. Objectives: We investigated whether melanoma acquired from patient-derived xenograft model (PDX) is well maintained and proliferated when tissue culture is performed in 3D bioprinited skin. Methods: The melanoma acquired from PDX was sectioned into 0.2-cm diameter and 0.1-cm height. They were cultured on 3D bioprinted collagen, dermis, and full-thickness skin, and the size change and cell viability of melanoma tissues were measured. Immunohistostaining and western blotting for cell markers of melanoma were performed. Results: The novel tissue culture model was well maintained until the 21st day. There was no significant change in diameter or height and cell viability. New melanoma nests proliferation was observed both grossly and microscopically at the 21st day. The characteristic findings of melanoma were well observed with immunohistostaining and western blotting. These results were best seen in the melanoma tissue culture with 3D bioprinted dermis group. Conclusion: Melanoma tissue culture with 3D bioprinted skin may be a novel method for melanoma culture and in vitro model of melanoma.

Recent trends of skin cancer in Korea from 2007 to 2013: a nation-wide cancer registry-based study with multicenter study

( Chul Hwan Bang ),( Hyun-min Seo ),( Ji Hyun Lee ),( Gyeong Mun Kim ),( Dong Soo Yu ),( Hyun Jeong Park ),( Shin Tack Oh ),( Hoon Kang ),( Chul Jong Park ),( Jeong Deuk Lee ),( Jun Young Lee ),( Youn 대한피부과학회 2016 대한피부과학회 학술발표대회집 Vol.68 No.2

Background: Although the incidence rates of skin cancers tend to increase, there have been few nation-wide epidemiologic studies on skin cancer in Korean. Objectives: We sought to investigate the incidence rates of skin cancers and time trends in Korean. Methods: We analyzed data of skin cancers from the Korean Central Cancer Registry (KCCR) from 2007 to 2013 and from our eight affiliated hospitals from 2007 to 2014. Results: Based on KCCR data and clinical records of dermatology outpatients from eight affiliated hospitals, a total of 27,757 cases were retrospectively reviewed. Overall incidence of skin cancer increased from 5.9/100,000 in 2007 to 9.2/100,000 in 2013. The incidence rates of non-melanoma skin cancer (NMSC) and malignant melanoma (MM) increased from 5.1 /100,000 to 8.3/100,000 and from 0.78/100,000 to 1.01/100,000 during the same period, respectively. BCC (75.5%) and MM (39.9%) were the most common skin cancer in the head and neck area and in the extremities, respectively. Conclusion: Our results suggest that recently the incidence rates of skin cancers have increased in Korean, and that epidemiological data from our study can contribute to establishing diagnostic and treatment guidelines for skin cancers in Korean.

자생 초화류 seedspray가 사면녹화에 미치는 영향

송정섭(Jeong Seob Song),장영득(Young Deug Chang),방창석(Chang Seok Bang),이상정(Sang Jeong Lee),정현환(Hyun Hwan Jeong) 한국원예학회 2002 한국원예학회 학술발표요지 Vol.2002 No.6

봉선화과 식물의 활용을 위한 문헌적 조사

방정환(Jeong Hwan Bang),정명수(Myong Soo Chong) 대한의료기공학회 2013 醫療氣功 Vol.13 No.1

In this study we examined the concerned literature for clinical use of Balsaminaceae plants focusing on the latest literature "zhong hua ben cao"(chinese materia medica, 1998). The findings were summarized as follows: 1. As an original plant, 27 species have been reviewed. 2. As a result of investigating oriental drug names by medicinal using part, a survey reported that the total of 22 species of oriental drug names, including 14 species of herba, 3 species of flos, 4 species of radix and rhizoma , and 1 species of semen, are being used for clinical use. 3. When we examined oriental drugs with five flavors by calculating and arranging their nature, effect, toxicity with points for conveniences sake, pungent and bitte showed 13 points, respectively, as main flavors. In drug nature, warm property of drug indicated 10 points and cold property of drug obtained 6 points. But as for other oriental drug, it is thought that we can recognize their significance. 4. With respect to efficacy, activating blood drug reached 10 kinds and wind- damp-dispelling 7 kinds, according to the examination. 5. In the examination on components and medicinal action, we examined that components are recorded in only impatiens balsamina's whole grass, flowers, root, root stems, and seeds, and Impatiens noli-tangere's whole grass. In medical action, we found out that the components are recorded in impatiens balsamina' flowers and seeds; impatiens noli-tangere's whole grass and flowers; and Impatiens textori' whole grass. 6. As a result of examining clinical prescription, the total of 84 kinds of clinical prescriptions by disease nature were examined, of which the prescription of Impatiens balsamina showed 19 cases in total, which was remarkable.

Liquid-Crystalline Semiconducting Copolymers with Intramolecular Donor−Acceptor Building Blocks for High-Stability Polymer Transistors

Kim, Do Hwan,Lee, Bang-Lin,Moon, Hyunsik,Kang, Hee Min,Jeong, Eun Jeong,Park, Jeong-Il,Han, Kuk-Min,Lee, Sangyoon,Yoo, Byung Wook,Koo, Bon Won,Kim, Joo Young,Lee, Wi Hyoung,Cho, Kilwon,Becerril, Hecto American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.17

<P>The ability to control the molecular organization of electronically active liquid-crystalline polymer semiconductors on surfaces provides opportunities to develop easy-to-process yet highly ordered supramolecular systems and, in particular, to optimize their electrical and environmental reliability in applications in the field of large-area printed electronics and photovoltaics. Understanding the relationship between liquid-crystalline nanostructure and electrical stability on appropriate molecular surfaces is the key to enhancing the performance of organic field-effect transistors (OFETs) to a degree comparable to that of amorphous silicon (a-Si). Here, we report a novel donor-acceptor type liquid-crystalline semiconducting copolymer, poly(didodecylquaterthiophene-alt-didodecylbithiazole), which contains both electron-donating quaterthiophene and electron-accepting 5,5'-bithiazole units. This copolymer exhibits excellent electrical characteristics such as field-effect mobilities as high as 0.33 cm(2)/V.s and good bias-stress stability comparable to that of amorphous silicon (a-Si). Liquid-crystalline thin films with structural anisotropy form spontaneously through self-organization of individual polymer chains as a result of intermolecular interactions in the liquid-crystalline mesophase. These thin films adopt preferential well-ordered intermolecular pi-pi stacking parallel to the substrate surface. This bottom-up assembly of the liquid-crystalline semiconducting copolymer enables facile fabrication of highly ordered channel layers with remarkable electrical stability.</P>

Effect of few-walled carbon nanotube crystallinity on electron field emission property

Hae-Deuk Jeong,Jong-Hyeok Lee,Byung-Gap Lee,Hee-Jin Jeong,Geon-Woong Lee,Dae-Suk Bang,Dong-Hwan Cho,Young-Bin Park,Kwang-Hwan Jhee 한국탄소학회 2011 Carbon Letters Vol.12 No.4

We discuss the influence of few-walled carbon nanotubes (FWCNTs) treated with nitric acid and/or sulfuric acid on field emission characteristics. FWCNTs/tetraethyl orthosilicate (TEOS) thin film field emitters were fabricated by a spray method using FWCNTs/TEOS sol one-component solution onto indium tin oxide (ITO) glass. After thermal curing, they were found tightly adhered to the ITO glass, and after an activation process by a taping method, numerous FWCNTs were aligned preferentially in the vertical direction. Pristine FWCNT/TEOS-based field emitters revealed higher current density, lower turn-on field, and a higher field enhancement factor than the oxidized FWCNTs-based field emitters. However, the unstable dispersion of pristine FWCNT in TEOS/N,N-dimethylformamide solution was not applicable to the field emitter fabrication using a spray method. Although the field emitter of nitric acid-treated FWCNT showed slightly lower field emission characteristics, this could be improved by the introduction of metal nanoparticles or resistive layer coating. Thus, we can conclude that our spray method using nitric acid-treated FWCNT could be useful for fabricating a field emitter and offers several advantages compared to previously reported techniques such as chemical vapor deposition and screen printing.