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Photocatalytic reduction of hexavalent chromium (Cr(VI)) using rotating TiO2 mesh
Jaekyung Yoon,Eunjung Shim,Hyunku Joo 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.5
An immobilized TiO2 electrode for photocatalytic hydrogen production is applied to reduce toxic Cr(Ⅵ) to non toxic Cr(Ⅲ) in aqueous solution under UV irradiation. To overcome the limitation of powder TiO2, a novel technique of immobilization based on anodization was applied and investigated under various experimental conditions. The anodization was performed with three different electrolytes (single or mixed), and then the anodized samples were annealed under an oxygen stream. Among the three kinds of anodized/annealed TiO2 on Ti foil, SampleⅡ(anodized at 20 V in 0.5% HF for 45 min at 5℃, and annealed at 450℃ for 5 hr in ambient oxygen at a flow rate of 400 mL/ min) was more effective for both Cr(Ⅵ) reduction than the other samples. Based on the electrolyte compositions, nanotubular TiO2 grown on Ti meshes was fabricated for the purpose of its light-harvesting ability and efficiency, where the anodized/annealed TiO2 on meshes were rotated in the center of the reactor and Cr(Ⅵ) could be effectively reduced at rotation speeds ranging from 0 to 64 rpm. In case of Sample Ⅱ, it was found that up to 98 % of the Cr(Ⅵ) was reduced in 30 min at 64 rpm.
Dennis Espineli Salcedo,Gijung Pak,Jaekyung Yoon,Sungpyo Kim 한국방재학회 2015 한국방재학회 학술발표대회논문집 Vol.14 No.-
One of the best solutions for the deficiency of clean water, especially for developing countries, is rainwater disinfection. In the past decades a lot of studies have been made to develop photocatalytic processes using TiO2 determining the performance on their surface oriented photocatalysis. However, most of these researches failed to consider the economical aspect as well as the effectiveness on the disinfection to antibiotic resistance genes. On the other hand, due to the issues of climate change and increased impermeable layer in urban area, flooding prevention is the best solution in water management systems. To remedy these two problems, a roof-harvested rainwater storage system was designed. In addition, a breakthrough technique using a solar simulator with self-rotating TiO2 nanotubes, to apply a photocatalytic system in disinfecting storage rainwater harvested from roof, was established. Roof-harvested storage rainwater was analysed for TN, TP, SS and COD. Aside from these parameters, Escherichia coli (with multidrug resistant pB10 plasmid) was added to the sample. Samples were injected to the self-rotating TiO2 nanotube reactor system with exposure time of 0 to 360 min and 7 different setups. Results show that the developed system has increased disinfection properties compared to negative samples, though the presence of antibiotic resistant bacteria.
Jaekyung Choi,Young Joon Yoon,Youn-Suk Choi,Hyo Tae Kim,김지훈,이종흔,Jong-hee Kim 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.2
A novel microfabrication process for the creation of a magnetohydrodynamic (MHD) mixer is presented using a photoimageable low temperature co-fired ceramic (LTCC). A monolithic structure was formed by UV photolithographic patterning and screen printing. The structure consists of a microfluidic channel and silver electrodes on a LTCC layer. The fluids in the microfluidic channel were controlled by a Lorentz force. A maximum mixing efficiency of 85.4% was achieved with AC peak-to-peak voltages of 8 V at 1 Hz. A photolithographic technique for patterning the microfluidic channel in the LTCC process is promising in order to realize a complex heterogeneous structure and it serves as an enabling tool in extending the applicability of ceramic-based microfluidic devices.
( Jaekyung Bae ),( Ji-Hyung Yoon ),( Jung-hee Lee ),( Jong-ho Nam ),( Chan-hee Lee ),( Jang-won Son ),( Ung Kim ),( Jong-seon Park ),( Dong-gu Shin ) 대한내과학회 2021 The Korean Journal of Internal Medicine Vol.36 No.6
Background/Aims: The clinical benefit of strict blood glucose-lowering therapy for patients with coronary artery disease (CAD) is still debated. We aimed to evaluate the long-term outcomes of patients with diabetes who under-went percutaneous coronary intervention (PCI), according to the mean hemoglobin A1c (HbA1c) level after PCI. Methods: We evaluated 675 diabetes patients with CAD treated with PCI. We categorized the study population into three groups based on the mean observed HbA1c levels during the follow-up duration, as follows: aggressive control (AC) group (HbA1c level < 6.5%, n = 148), moderate control (MC) group (HbA1c level ≥ 6.5% and < 7.0%, n = 138), and uncontrolled (UC) group (HbA1c level ≥ 7.0%, n = 389). The primary endpoint was major adverse cardiovascular and cerebrovascular events (MACCEs), defined as cardiac death, myocardial infarction, repeat target vessel revascularization, and stroke. Results: The mean HbA1c level of the AC group was significantly lower than that of the MC and UC groups (6.04% ± 0.36% vs. 6.74% ± 0.14% vs. 8.39% ± 1.20%, p < 0.001). The incidence of MACCEs was significantly lower in the AC group than in the MC and UC groups (16.0% vs. 24.3% vs. 26.3%, p = 0.010), mostly driven by the incidence of stroke (4.4% vs. 14.0% vs. 11.4%, p = 0.013). Multivariate Cox regression analysis showed that only the AC group was associated with a reduced rate of MACCEs (hazard ratio, 0.499; 95% confidence interval, 0.316 to 0.786; p = 0.004) com-pared with the UC group. Conclusions: Our study showed that intensive glycemic control (HbA1c level < 6.5%) is associated with improved clinical outcomes after PCI in patients with diabetes.
국내 범죄학연구의 통계자료 사용현황과 분석방법 : 학술지 논문을 중심으로(2016-2020)
안재경 ( Jaekyung Ahn ),김윤 ( Youn Kim ),윤민영 ( Minyeong Yoon ),최재훈 ( Jaehun Choi ),노승국 ( Seungkook Roh ) 대한범죄학회 2020 한국범죄학 Vol.14 No.3
본 연구는 국내 범죄학연구에 주로 사용되는 연구자료와 방법론을 살펴보고, 이를 바탕으로 범죄통계자료의 수집방향과 향후 후속연구의 방향에 대해 제언하기 위하여 실시되었다. 이를 위해 범죄학 관련 대표적인 학술지 4개인 ‘한국범죄학’, ‘경찰학연구’, ‘치안정책연구’, ‘형사정책연구’를 대상으로 연구내용, 사용자료, 연구방법 등을 살펴보았다. 총 591건의 연구논문 중에서 범죄학을 주제로 한 양적논문 140편을 선정하여 분석한 결과, 범죄학 양적 연구의 발표 건수는 2016년부터 현재까지 꾸준히 증가하고 있는 것으로 나타났다. 학술지 별로 살펴보면 한국범죄학은 게재된 범죄학 양적분석 논문의 수가 많지만 비교적 공적 공개자료를 사용한 논문이 많이 투고되고, 공적 비공개자료를 이용한 논문은 경찰학연구에 많이 투고되는 것을 알 수 있었다. 분석결과 2017년도에 접어들면서 다양한 형태의 고급 통계 연구방법론이 사용되고 있었다. 또 일반대학 소속 저자는 ‘한국범죄학’에, 경찰청 및 소속 교육기관의 저자는 ‘경찰학연구’ 학술지에 주로 투고하는 경향이 있었다. 이러한 논의를 바탕으로 향후 범죄통계 수집과 범죄학연구의 방향에 대해서 제언하였다. This study was conducted to investigate the current state of criminology research in Korea and to suggest the direction and tasks of future research in criminology research. To this end, four representative journals related to criminology ‘Journal of Korean Criminological Association’, ‘The Journal of Police Science’, ‘The Journal of Police Policies’ and ‘Korean Criminological Review’were selected,. Among a total of 591 research papers, 140 quantitative papers on the subject of criminology were selected and analyzed according to the research content, materials, and methods. As a result, the number of publications of quantitative criminology studies has been steadily increasing from 2016 to the present. By looking at the journals, it was found that although the number of quantitative analysis papers on criminology is large in ‘Journal of Korean Criminological Association’, a lot of papers using publicly public data are submitted. Also, many papers using publicly non-public data are submitted to ‘The Journal of Police Policies’. In terms of research methodology, it was found that various types of advanced statistical methodology were used since 2017. In addition, authors from general universities tend to submit to ‘Journal of Korean Criminological Association’, and authors from the National Police Agency and affiliated educational institutions tend to submit to ‘The Journal of Police Science’. Based on these discussions, future direction of collecting crime statistics were proposed.