• 멤브레인
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• 제32권5호
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• pp.336-347
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• 2022

역전기투석(reverse electrodialysis, RED)은 이온교환막을 격막으로 이용하여 해수와 담수의 농도차로부터 발전하는 유망한 친환경 재생에너지 기술 중 하나이다. 이온교환막은 RED의 성능을 좌우하는 핵심 구성요소로 낮은 전기적 저항, 높은 이온선택투과도, 우수한 내구성 및 저렴한 제조 비용 등의 요구조건을 만족시켜야 한다. 본 연구에서는 다양한 두께 및 기공율을 갖는 다공성 고분자 지지체를 이용하여 세공충진 음이온교환막을 제조하고 이온교환 고분자의 조성과 막 두께가 RED의 발전 성능에 미치는 영향을 조사하였다. 이온교환막의 전기적 저항이 충분히 낮은 경우 RED 발전 성능은 주로 막의 apparent permselectivity에 의해 좌우됨을 확인할 수 있었다. 또한 막의 apparent permselectivity는 IEC, 가교도, 막 두께, 표면 개질 등을 통해 향상시킬 수 있으며 전기적 저항과의 trade off 관계를 고려하여 최적 조건을 찾아야 함을 확인하였다.

• 멤브레인
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• 제33권6호
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• pp.315-324
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• 2023

이온교환막은 전기막 공정의 성능을 결정하는 핵심 구성 요소이다. 본 총설에서는 다양한 전기막 공정에 적용되는 이온교환막의 성능을 탄소계 및 금속계 나노물질을 이용한 개질을 통해 향상시킨 최신 연구 동향을 살펴보았다. 나노물질들은 다양한 방법을 통해 이온교환막에 도입될 수 있다. 특히 탄소계 나노물질은 화학적 개질을 통해 추가적인 기능기를 도입함으로써 고분자 사슬과의 상호작용을 강화할 수 있다. 이를 통해 이온교환막의 이온전도도를 개선시킬 수 있을 뿐만 아니라 적층 구조를 통한 체거름 현상으로 이온 선택 투과성을 향상시킬 수 있다. 한편, 금속계 나노물질은 적층 구조 혹은 다공성 구조를 갖는 특성을 이용하여 이온교환막 내에서 목적 이온과 배제 이온 간의 수화 반경 차이를 이용한 체거름 특성을 통해 이온 선택 투과성을 향상시킬 수 있다. 또한, 사용한 바인더의 특성에 따라서는 나노물질-바인더 간의 상호작용을 통해 이온전도도도 향상시킬 수 있다. 본 총설로부터 탄소계 및 금속계 나노물질을 이용하여 이온교환막의 특성을 효과적으로 조절할 수 있으며, 따라서 이에 관한 연구가 전기막 공정의 성능을 크게 향상시키기 위해 중요함을 확인할 수 있다.

• Journal of Electrochemical Science and Technology
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• 제15권1호
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• pp.168-177
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• 2024

Ni-rich cathode is one of the promising candidates for high-energy lithium-ion battery applications. Due to its specific capacity, easy industrialization, and good circulation ability, Ni-rich cathode materials have been widely used for lithium-ion batteries. However, due to the limitation of the co-precipitation method, including sewage pollution, and the instability of the long production cycles, developing a new efficient and environmentally friendly synthetic approach is critical. In this study, the Ni_0.91Co_0.06Mn_0.03CO₃ precursor powder was successfully synthesized by an efficient spray-drying method using carbonate compounds as a raw material. This Ni_0.91Co_0.06Mn_0.03CO₃ precursor was calcined by mixing with LiOH·H₂O (5 wt% excess) at 480℃ for 5 hours and then sintered at two different temperatures (780℃/800℃) for 15 hours under an oxygen atmosphere to complete the cathode active material preparation, which is a key component of lithium-ion batteries. As a result, LiNi_0.91Co_0.06Mn_0.03O₂ cathode active material powders were obtained successfully via a simple sintering process on the Ni_0.91Co_0.06Mn_0.03CO₃ precursor powder. Furthermore, the obtained LiNi_0.91Co_0.06Mn_0.03O₂ cathode active material powders were characterized. Overall, the material sintered at 780℃ shows superior electrochemical performance by delivering a discharge capacity of 190.76 mAh/g at 1^st cycle (0.1 C) and excellent capacity retention of 66.80% even after 50 cycles.

• 생약학회지
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• 제15권2호
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• pp.61-73
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• 1984

To investigate antitumor component of Lyophyllum decastes, the aqueous extract of its shake-cultured mycelia was subjected to antitumor test against sarcoma 180 cells implanted in ICR mice. The extract showed an inhibition ratio of 65.4% and was found to consist of a polysaccharide moiety and a protein moiety. After purification with DEAE-Sephadex A-50 ion exchange chromatography, Fraction D showed the highest inhibition ratio of 75.7%. The antitumor constituent was examined for immunoaccelerating activity and was found to increase macrophage accumulation in the peritoneal cavity and plaque forming cells of the spleen cells. It was named lyophyllan after the genus name.

• 대한약리학회지
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• 제6권1호
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• pp.1-7
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• 1970

The effects of ouabain and diphenylhydantoin on ATPase activity in rat erythrocyte membranes were studied and also influence of K on ATPase activity was studied. The ATPase activity of rat erythrocyte membrane has been shown to consist of two components. The first component requires the Mg but occurs in the absence of Na or K (Mg-ATPase) and is not inhibited by ouabain and stimulated by diphenylhydantoin. The second component requires the presence of Mg and also Na or K (Na-K-Mg-ATPase). It is inhibited by ouabain and is stimulated by diphenylhydantoin in low Na concentration and inhibited in high Na concentration. K inhibit Na-K-Mg-ATPase which is inhibited by ouabain. Ouabain and diphenylhydantoin show reversed effect to Na-K-Mg-ATPase activity. It suggest that the therapeutic effect of diphenylhydantoin on digitalis induced cardiac arrhythmia may be resulted from their effect on ion transport mechanism of cell membrance. And the relevance of these findings to the action of ouabain and diphenylhydantoin on membrane transport mechanism is discussed.

• 한국군사과학기술학회지
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• 제8권3호
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• pp.83-91
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• 2005

Pyrolysis-mass spectrometry has been used to characterize the 17 biological materials including bacteria and proteins. In this study, an in situ thermal-hydrolysis methylation(THM) procedure using tetramethylammonium hydroxide(TMAH) was employed. The biological materials are ionized using chemical ionization(CI) method with ethanol by ion trap mass spectrometer(ITMS), which attached with our own made pyrolyzer module, and then their pyrolysis mass spectra were obtained. The major distinct characteristic peaks were selected from all the range of mass spectra, and analyzed using principal component analysis(PCA) method to assess the classification/identification possibility of biological materials.

• Bulletin of the Korean Chemical Society
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• 제20권12호
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• pp.1501-1505
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• 1999

Expansion dynamics of C$^{+}$ ions ejected from 355-nm laser ablation of graphite target in vacuum has been investigated by pulsed-field time-of-flight (TOF) mass spectrometry. A strong nonlinear dependence of the amount of desorbed C$^{+}$ ions on laser fluence is interpreted by the mechanism that C$^{+}$ ions are produced directly from the graphite via conversion of the multiphoton energy into thermal energy. The temporal evolution of C$^{+}$ ions was measured by varying the delay time of the ion repelling pulse with respect to the laser irradiation, which provides significant information on the ablated plume characterization. The TOF distributions of ablated ions showed a bimodal shape and could be fitted by shifted Maxwell-Boltzmann distributions. The velocity of the fast component increases with the delay time, whereas the slow component (< 500 m/s) exhibits a constant velocity. Also studied were the effects of the laser fluence on the energetics of C$^{+}$ ions.

• 한국대기환경학회지
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• 제13권1호
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• pp.51-63
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• 1997

Total suspended particulate matters in the ambient air were analyzed for eight chemical elements (Ca, Co, Cu, Fe, Mn, Pb, Si, and Zn) using an x-ray fluorescence spectrometry (XRF) at the Kyung Hee University - Suwon Campus during 1989 to 1994. To use these data as basis for source identification study, membership of each sample was selected to represent one of the well defined sample groups. The data sets consisting of 83 objects and 8 variables were initially separated into two groups, fine (d$_{p}$<3.3 ${\mu}{\textrm}{m}$) and coarse particle groups (d$_{p}$>3.3 ${\mu}{\textrm}{m}$). A hierarchical clustering method was examined to obtain possible member of homogeneous sample classes for each of the two groups by transforming raw data and by applying various distances. A disjoint principal component analysis was then used to define homogeneous sample classes after deleting outliers. Each of five homogeneous sample classes was determined for the fine and the coarse particle group, respectively. The data were properly classified via an application of logarithmic transformation and Euclidean distance concept. After determining homogeneous classes, correlation coefficients among eight chemical variables within all the homogeneous classes for calculated and meteorological variables (temperature. relative humidity, wind speed, wind direction, and precipitation) were examined as well to intensively interpret environmental factors influencing the characteristics of each class for each group. According to our analysis, we found that each class had its own distinct seasonal pattern that was affected most sensitively by wind direction.ion.

• 한국세라믹학회지
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• 제49권2호
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• pp.185-190
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• 2012

The purpose of this study was to examine a possibility that fly ash could be used as raw material for carbonation by conducting the experiment on magnetic separation and hydration of fly ash that contained a large amount of CaO composite. Wet magnetic separation experiment was performed to remove the component of magnetic substance that contained fly ash, which aimed at increasing the content of CaO in the non-magnetic domain. The selected fly ash was used for hydration experiment before the TG-DTA, XRF and XRD analyses were made to confirm the Ca component that could be carbonated. Then, the fly ash was turned to a hydrate that was favorable to dissociation of $Ca^{2+}$ ion. As a result, the magnetic separation enabled detecting the content of CaO component by up to 61 wt% in the non-magnetic domain. Since the hydrate was confirmed, it is believed that the fly ash can be used as raw material for carbonation.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2009년도 추계학술대회 논문집
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• pp.272-273
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• 2009