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- 저자 : 이혜련 ( Hyeryeon Lee ) (검색결과 5 건)
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플라즈마 및 직접 기상 불소화에 의해 제어된 산소결핍 불소화 WO<sub>3</sub> 광촉매의 광분해 특성
이혜련,이란은,김대섭,이영석,Lee, Hyeryeon,Lee, Raneun,Kim, Daesup,Lee, Young-Seak 한국공업화학회 2022 공업화학 Vol.33 No.2
To enhance the photocatalytic activities of WO<sub>3</sub> photocatalysts, fluorine doping was performed to induce the oxygen vacancies. Both plasma and direct vaper fluorination were carried out for fluorine doping, and photocatalytic activities were examined by using methylene blue dye. Oxygen vacancies of the plasma and direct vaper fluorinated WO<sub>3</sub> photocatalysts were measured to be 14.65 and 18.59%, which increased to about 23 and 56% at pristine WO<sub>3</sub> photocatalysts. The degradation efficiency of methylene blue was also determined about 1.7 and 3.4 times higher than pristine WO<sub>3</sub> photocatalysts, respectively, depending on oxygen vacancies increased. In addition, it was confirmed that the bandgap process energy decreased from 2.95 eV to 2.64 and 2.45 eV after fluorine doping. From this result, it is considered that the direct vaper fluorination has an advantage for increasing the photocatalytic activities of WO<sub>3</sub> compared to that of the plasma fluorination.
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기상 불소화법을 이용한 WO3-xFx 광촉매의 합성 및 광분해 특성
이혜련 ( Hyeryeon Lee ),임채훈 ( Chaehun Lim ),이란은 ( Raneun Lee ),이영석 ( Young-seak Lee ) 한국공업화학회 2021 공업화학 Vol.32 No.6
In this research, fluorine doping was performed to enhance the photocatalytic activities of WO<sub>3</sub> which were measured using methylene blue dye. WO<sub>3-x</sub>F<sub>x</sub> photocatalyts were prepared by a vaper phase fluorination during a sintering for preparing WO<sub>3</sub> photocatalysts from a WCl<sub>6</sub> precursor. The bandgap energy of WO<sub>3</sub> photocatalysts decreased from 2.95 eV to 2.54 eV, and the oxygen vacancies site increased by about 55% after fluorine doping. In addition, the initial degradation efficiency of methylene blue showed that the fluorine doped sample showed a 6-fold increase in photocatalytic activities from 10% to 60% compared to that of the untreated sample. It is believed that fluorine is doped to reduce the band gap of photocatalysts, enabling the catalytic activity with low energy, and that oxygen vacancies-generated surface defects increase the visible light absorption region of WO<sub>3</sub> photocatalysts, thereby increasing photocatalytic activity. In this study, it was confirmed that fluorine-doped WO<sub>3-x</sub>F<sub>x</sub> photocatalysts with an excellent photocatalytic activity can be manufactured easily using a one-step vaper phase fluorination that does not require a post-treatment process.
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질소 플라즈마 표면처리가 쌀겨 기반 활성탄소의 전기 이중층 커패시터 성능에 미치는 영향
이란은 ( Raneun Lee ),곽철환 ( Cheol Hwan Kwak ),이혜련 ( Hyeryeon Lee ),김석진 ( Seokjin Kim ),이영석 ( Young-seak Lee ) 한국공업화학회 2022 공업화학 Vol.33 No.1
바이오매스 활용을 높이기 위하여, 쌀겨 기반 활성탄소(RHAC)를 제조한 뒤 질소 플라즈마 표면처리를 수행하여 전기이중층 커패시터(EDLC) 성능을 고찰하였다. 질소 플라즈마 표면처리를 통하여, RHAC 표면에 최대 2.17%의 질소가 도입되었으며 특히, 5 min 동안 반응한 샘플의 경우 pyrrolic/pyridine계 N 작용기의 형성이 우세하였다. 또한, 실리카제거에 의해 쌀겨 기반 탄소재에 메조기공이 형성되었고 질소 플라즈마 표면처리에 의해 탄소재 표면 거칠기가 증가하여 미세기공이 많이 형성되는 것을 확인할 수 있었다. 순환전압전류법 측정 실험으로부터, 5 mV/s의 전압 주사 속도에서 질소 플라즈마 처리된 RHAC의 비정전용량은 최대 200 F/g로, 미처리 RHAC (111 F/g)에 비교하여 80.2% 향상된 값을 나타내었다. 이러한 결과는 질소 플라즈마 표면처리로 인해 탄소재 표면에 도입된 pyrrolic/pyridine계 질소 작용기 도입과 탄소재 표면 미세기공 부피 향상으로 인한 시너지 효과인 것으로 판단된다. 본 연구는 폐기 자원을 재활용하고, 플라즈마 표면처리법을 통해 이종원소 도입을 한다는 점에서 환경적으로 긍정적인 영향을 미칠 것으로 사료된다. To increase biomass utilization, rice husk-based activated carbon (RHAC) followed by nitrogen plasma surface treatment was prepared and the electric double-layer capacitor performance was investigated. Through nitrogen plasma surface treatment, up to 2.17% of nitrogen was introduced to the surface of RHAC, and in particular the sample reacted for 5 min with nitrogen plasma showed dominant formation of pyrrolic/pyridine N functional groups. In addition, mesopores were formed on the RHAC material by the removal of silica, and the surface roughness of the carbon material increased by nitrogen plasma surface treatment, resulting in the formation of many micropores. As a result of cyclic voltammetry measurement, at a scan rate of 5 mV/s, the specific capacitance of the RHAC treated with nitrogen plasma increased up to 200 F/g, showing an 80.2% improvement compared to that of using untreated RHAC (111 F/g). This is attributed to the synergetic effect of the introduction of pyrrolic/pyridine-based nitrogen functional groups and the increase of the micropore volume on the surface of the carbon material. This study has a positive effect on the environment in terms of recycling waste resources and using plasma surface treatment.
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Association of Sasang Constitutional Type with Bone Mineral Density, Osteopenia, and Osteoporosis
이승구,윤대위,김종렬,김진관,이혜련,이성희,애보트 로버트,신철,Lee, Seung Ku,Yoon, Dae Wui,Kim, Jong Yeol,Kim, Jin Kwan,Yi, Hyeryeon,Lee, Sunghee,Abbott, Robert D.,Shin, Chol The Society Of Sasang Constitutional Medicine 2020 사상체질의학회지 Vol.32 No.3
Object Although Taeeum and Soyang constitutional types have bigger body shapes and higher body mass index values than those with the Soeum, the relationship between the Sasang constitutional type and bone mass density is controversial and the association of osteopenia and osteoporosis remains unknown. Therefore, we investigated the relationship between bone mineral density, osteopenia, and osteoporosis according to Sasang constitutional type. Methods A total of 2,508 participants were included in this study. Among the study participants, 1,396 had Taeeum type, 276 had Soeum type, and 836 had Soyang type, respectively. The relationships to bone mass density, osteopenia, and osteoporosis in those with Sasang constitutional type were estimated using logistic and linear regression models. Results Bone mass density was significantly higher in the order of Taeeum, Soyang, and Soeum group (p < 0.01). Soeum group in comparison with Taeeum or Soyang group was significantly associated with a high odds ratio for osteopenia and osteoporosis except in the hip and femoral neck in the comparison of Taeeum and Soeum group (p < 0.01). Moreover, the bone mass density of Soeum group decreased more rapidly as the age increased when compared with Taeeum and Soyang group. Conclusions Our findings may contribute to the early prevention and management of high-risk individuals with poor bone mass density, osteopenia, and osteoporosis using Sasang constitution medicine.
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