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Chae-Wook Cho,Dong-Hwan Cho,Young-Gwang Ko,Oh-Hyeong Kwon,Inn-Kyu Kang 한국탄소학회 2007 Carbon Letters Vol.8 No.4
In the present study, electrospun PAN precursor webs and the stabilized and carbonized nanofiber webs processed under different heat-treatment conditions were characterized by means of weight loss measurement, elemental analysis, scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimentric analysis (TGA), and X-ray diffraction (XRD) analysis. The result indicated that stabilization and carbonization processes with different temperatures and heating rates significantly influenced the chemical and morphological characteristics as well as the thermal properties of the stabilized and then subsequently carbonized nanofiber webs from PAN precursor webs. It was noted that the filament diameter and the carbon content of a carbonized nanofiber web as well as its weight change may be effectively monitored by controlling both stabilization and carbonization processes.
Cho, Chae-Wook,Cho, Dong-Hwan,Ko, Young-Gwang,Kwon, Oh-Hyeong,Kang, Inn-Kyu Korean Carbon Society 2007 Carbon Letters Vol.8 No.4
In the present study, electrospun PAN precursor webs and the stabilized and carbonized nanofiber webs processed under different heat-treatment conditions were characterized by means of weight loss measurement, elemental analysis, scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimentric analysis (TGA), and X-ray diffraction (XRD) analysis. The result indicated that stabilization and carbonization processes with different temperatures and heating rates significantly influenced the chemical and morphological characteristics as well as the thermal properties of the stabilized and then subsequently carbonized nanofiber webs from PAN precursor webs. It was noted that the filament diameter and the carbon content of a carbonized nanofiber web as well as its weight change may be effectively monitored by controlling both stabilization and carbonization processes.
레이온직물의 특성에 미치는 등온 안정화공정 및 초음파세척의 영향
조채욱 ( Chae Wook Cho ),조동환 ( Dong Hwan Cho ),박종규 ( Jong Kyoo Park ),이재열 ( Jae Yeol Lee ) 한국접착및계면학회 2013 접착 및 계면 Vol.14 No.1
셀룰로오스계 레이온섬유 또는 레이온직물은 좁은 온도범위의 안정화공정 동안에 열분해가 매우 빠르게 진행된다. 그러므로 레이온계 탄소섬유를 제조하는데 있어 안정화단계는 매우 중요한 핵심공정이다. 따라서 본 연구에서는 셀룰로오스계 레이온직물의 중량감소, 화학조성, 미세구조 및 texture 변화에 미치는 등온 안정화공정과 초음파세척의 영향을 조사하였다. 200∼240°C 영역에서 행한등온 안정화공정의 온도는 레이온직물을 안정화 소요시간, 탄소함량, 산소함량, 셀룰로오스 구조 변화 그리고 직물 texture에 큰 영향을 주었다. 등온 안정화공정 전에 물을 이용한 초음파세척은 레이온직물의 안정화공정 시간을 단축하고, 안정화 후 직물의 탄소함량을 증가하고, 산소함량을 감소시키며, XRD 분석 패턴을 변화시키는데 역할을 하는 것으로 조사되었다. 또한 초음파세척은 등온 안정화공정시 발생하는 레이온직물의 빠른 중량감소 현상을 더디게 하고, 열수축을 감소시켜, 직물의 급격한 물리적 변화의 완화에도 기여하는 것으로 사료된다. Cellulose-based rayon fibers or fabrics can be thermally decomposed very fast within a narrow temperature window during stabilization process. Therefore the stabilization stage is critically important for producing rayon-based carbon fibers. Consequently, in the present study the effects of isothermal stabilization and ultrasonic cleaning on the weight loss, chemical composition, microstructure, and fabric texture of cellulose-based rayon fabrics were explored. The temperature of the isothermal stabilization process performed in the range of 200∼240°C influenced the processing time, carbon and oxygen contents, cellulose structural change, and fabric texture. The ultrasonic cleaning, which was conducted prior to the stabilization process, played a role in shortening the stabilization time, increasing the carbon contents, decreasing the oxygen contents, and changing the XRD pattern. Also, it was considered that the ultrasonic cleaning contributed to retarding the weight loss, to reducing the thermal shrinkage, and further to reducing the fast physical change of rayon fabrics.
빠르게 안정화된 레이온직물의 특성에 미치는 초음파세척 및 화학전처리 영향
조채욱 ( Chae Wook Cho ),조동환 ( Dong Hwan Cho ) 한국접착및계면학회 2013 접착 및 계면 Vol.14 No.3
본 연구에서는 350°C에서 4 min 이내로 빠르게 등온 안정화공정을 통해 얻어진 레이온직물의 화학조성, 물리적 특성, X-선 회절 패턴, 열안정성 그리고 직물 형상에 미치는 초음파세척 및 화학전처리의 영향을 조사하였다. 안정화공정 동안 레이온직물에서 발생하는 중량감소와 열수축을 줄이고 안정화반응을 촉진시키기 위하여 안정화공정 전에 레이온직물을 먼저 초음파 세척하고 NH4Cl, Na3PO4, H3PO4 및 ZnCl2로 화학전처리 공정을 수행하였다. 결과는 초음파세척 및 화학전처리가 안정화된 레이온직물의 중량감소, 열수축, 미세구조 변화, 탄소함량, 열안정성, 및 직물 형상에 영향을 주었으며, 사용한 안정화시간과 화학전처리제의 종류에 의존하였다. In the present study, stabilized rayon fabrics were prepared from fast isothermal stabilization processes, which were carried out within four minutes at 350°C. The effects of ultrasonic cleaning and chemical pre-treatment on the chemical composition, physical characteristics, X-ray diffraction pattern, thermal stability and shape of the stabilized rayon fabrics were investigated extensively. In order to reduce the weight loss and thermal shrinkage of rayon fabrics occurring during the stabilization process, ultrasonic cleaning was first conducted and then chemical pre-treatments using NH4Cl, Na3PO4, H3PO4, and ZnCl2 were performed, respectively. The results indicated that both ultrasonic cleaning and chemical pre-treatment influenced the weight loss, thermal shrinkage, microstructure, carbon content, thermal stability and fabric shape of stabilized rayon fabrics. Also the results depended on the fast-stabilization time and the type of chemical pre-treatment agents used.
Cho, Young-Seok,Chae, Hiun-Suk,Kim, Hyung-Keun,Kim, Jin-Soo,Kim, Byung-Wook,Kim, Sung-Soo,Han, Sok-Won,Choi, Kyu-Yong WJG Press 2008 WORLD JOURNAL OF GASTROENTEROLOGY Vol.14 No.13
<P>To compare the hemostatic efficacy and safety of two mechanical endoscopic methods: endoscopic band ligation (EBL) and endoscopic hemoclip placement (EHP) in patients with actively bleeding Mallory-Weiss syndrome (MWS).</P>
한국 군장병 삼일열 말라리아(P. vivax) 진단에 OptiMAL 검사와 GENEDIA Malaria (P. vivax) Ab Rapid I, II 검사의 비교
조덕,임재균,이상오,소병조,임채승,양동욱 대한감염학회 2001 감염 Vol.33 No.4
Background : The diagnosis of malaria has been usually made using microscopic examination of Wright stained thin blood films in Korean army. This method is labor-intensive, time consuming and requires the microscopic expertise. Therefore, the alternative techniques, rapid diagnostic test, have been sought for use in Korean army. We performed a comparison of the OptiMAL test with GENEDIA Malaria (P. vivax) Ab Rapid I, II to assess its sensitivity and specificity of Plasmodium vivax malaria. Methods : Blood specimen were collected from 51 patients who were presented and initially diagnosed for P. vivax by the microscopy of blood smears and from 30 control patients without malaria infection at the Capital Armed Forces General Hospital (CAFGH) between October 2000 and February 2001. Among the 51 patients, we also collected 24 samples from 24 patients at 2 or 3 days after therapy. The OptiMAL test and GENEDIA Malaria (P. vivax) Ab Rapid I, II were performed according to the manufacturer's instructions on all samples respectively. Results : Compared with the blood firm, sensitivities and specificities of the OptiMAL test, GENEDIA Malaria (P. vivax ) Ab Rapid I and GENEDIA Malaria (P. vivax) Ab Rapid II were 94.1∼100% (29/29), 80.4∼83.3%, 96.1 ∼96.7% respectively. One case was interpreted as 'undetermined' by OptiMAL test. In 24 patients during therapy, the sensitivities of the OptiMAL test, GENEDIA Malaria (P. vivax) Ab Rapid I and GENEDIA Malaria (P. vivax) Ab Rapid II on 8 specimens with mean 120/□ parasitemia and 16 specimens with negative parasitemia were 75∼43.8%, 87.5∼81,3%, 100∼100% respectively. Conclusion : Our data demonstrated that the sensitivity and specificity of the GENEDIA Malaria (P. vivax) Ab Rapid I were not satisfactory, but the sensitivity and specificity of the OptiMAL test and GENEDIA Malaria (P. vivax) Ab Rapid II were relatively high and useful diagnostic tests for diagnosis of , P. vivax in areas like the militaries where laboratory facilities are poor or non-existent. (Korean J Infect Dis 33:267∼272, 2001)
Ribosomal protein mutations in Korean patients with Diamond-Blackfan anemia
Chae, Hyojin,Park, Joonhong,Lee, Seungok,Kim, Myungshin,Kim, Yonggoo,Lee, Jae-Wook,Chung, Nack-Gyun,Cho, Bin,Chul Jeong, Dae,Kim, Jiyeon,Kim, Jung Rok,Park, Geon Nature Publishing Group 2014 Experimental and molecular medicine Vol.46 No.3
<P>Diamond-Blackfan anemia (DBA) is a congenital bone marrow failure syndrome characterized by hypoproliferative anemia, associated physical malformations and a predisposition to cancer. DBA has been associated with mutations and deletions in the large and small ribosomal protein genes, and genetic aberrations have been detected in ∼50–60% of patients. In this study, nine Korean DBA patients were screened for mutations in eight known DBA genes (<I>RPS19, RPS24, RPS17, RPS10, RPS26, RPL35A, RPL</I>5 and <I>RPL11</I>) using the direct sequencing method. Mutations in <I>RPS19, RPS26</I> and <I>RPS17</I> were detected in four, two and one patient, respectively. Among the mutations detected in <I>RPS19</I>, two mutations were novel (c.26T>A, c.357-2A>G). For the mutation-negative cases, array-CGH analysis was performed to identify copy-number variations, and no deletions involving the known DBA gene regions were identified. The relative mRNA expression of <I>RPS19</I> estimated using real-time quantitative PCR analysis revealed two- to fourfold reductions in <I>RPS19</I> mRNA expression in three patients with <I>RPS19</I> mutations, and p53 protein expression analysis by immunohistochemistry showed variable but significant nuclear staining in the DBA patients. In conclusion, heterozygous mutations in the known DBA genes <I>RPS19</I>, <I>RPS26</I> and <I>RPS17</I> were detected in seven out of nine Korean DBA patients. Among these patients, <I>RPS19</I> was the most frequently mutated gene. In addition, decreased <I>RPS19</I> mRNA expression and p53 overexpression were observed in the Korean DBA patients, which supports the hypothesis that haploinsufficiency and p53 hyperactivation represent a central pathway underlying the pathogenesis of DBA.</P>