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Ko Gyeol 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7
The vast growth of the manufacturing world is producing a massive amount of wastewater from a wide range of industrial applications disposed into surface water. Undoubtedly, these effluents contain a variety of high-toxic compounds that pose a real challenge and dislocate the environment. The reverse osmosis (RO) process is recognized as a superior method due to its reliability in generating a roughly pure reuse water at a plausible cost. However, the literature has a shortage of comprehensive studies to simultaneously eliminate organic and non-organic compounds from wastewater using a predefined multi stage direct pass operation of a spiral wound module of RO process. To systematically carry out this, a mathematical model developed by the same author has been modified to critically predict the efficiency of RO process towards the simultaneous removal of multi-component from wastewater. For this system, the simulation introduces realistic operating circumstances that correspond to a high rejection of the targeted chemicals. By optimizing the design operating conditions, the accompanying treatment process’ consistency and effectiveness are also increased. As a result, there was a noticeable decline in the unintended release of the harmful substances into the recycled water within a fixed specific energy consumption.
Ko, Gyeol,Seo, Yongwon American Chemical Society 2019 Environmental science & technology Vol.53 No.21
<P>SF<SUB>6</SUB> hydrate formation behaviors in various reaction media, such as bulk water, porous silica gel, and hollow silica, were investigated for hydrate-based SF<SUB>6</SUB> separation with a primary focus on thermodynamic stability and formation kinetics. The measured three-phase (H-L<SUB>W</SUB>-V) equilibria demonstrated that the types of reaction media used in this study had no effect on the thermodynamic stability of SF<SUB>6</SUB> hydrates. The dissociation enthalpy (Δ<I>H</I><SUB>d</SUB>) of SF<SUB>6</SUB> hydrate was measured using a high-pressure micro-differential scanning calorimeter, and it corresponded well with estimates from the Clausius-Clapeyron equation. The unstirred porous silica gel system showed a larger gas uptake and a higher growth rate at the early stage of SF<SUB>6</SUB> hydrate formation. However, the gas uptake and growth rate of SF<SUB>6</SUB> hydrates in stirred bulk water and unstirred hollow silica were significantly increased at a larger temperature driving force or in the presence of sodium dodecyl sulfate. The experimental results obtained in this study will be very helpful for a better understanding of the thermodynamic and kinetic characteristics of SF<SUB>6</SUB> hydrate formed in various reaction media and in surfactant-added solution, and are expected to contribute to further development of the hydrate-based SF<SUB>6</SUB> separation process.</P> [FIG OMISSION]</BR>
Ko Gyeol,Kim Eunae,이동영,서용원 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7
Fluorinated gases (F-gases), such as CHF3 and C2F6, which are used in the semiconductor industry and have considerable global warming potential, can be recovered after use through a gas hydrate-based separation method to prevent their release into the atmosphere. In this study, the guest distributions and dissociation enthalpy (ΔHd) of F-gas (CHF3 or C2F6)+N2 hydrates with different F-gas concentrations (CHF3: 20%, 80%, and 100% and C2F6: 20%, 60%, 80%, and 100%) were experimentally investigated using a powder X-ray diffractometer and a high-pressure micro-differential scanning calorimeter, respectively. At high N2 concentrations in the feed gas, the occupancy of N2 in the small (512) cages of the F-gas+N2 hydrates increased significantly. As a result, the F-gas+N2 hydrates exhibited reduced hydration numbers at high N2 concentration. The ΔHd values (in kJ/mol gas) of the F-gas (CHF3 or C2F6)+N2 hydrates decreased with increased N2 concentration. The overall experimental results provide useful insights into the design and operation of gas hydrate-based F-gas separation processes.
이한결(Han-Gyeol Lee),고대식(Dae-Sik Ko),정대인(Dae-In Jung) 대한심장호흡물리치료학회 2022 대한심장호흡물리치료학회지 Vol.10 No.1
Purpose: The study aimed to investigate the effect of round shoulder posture correction on respiration and concentration. Methods: A total of 34 college students were included in this study. The participants were divided into three groups: group 1, stretching and stability (n = 12); group 2, stretching and strengthening (n = 12), and group 3, control (10). The exercise interventions were conducted for 4 weeks. Group 1 performed warm-up, stretching, muscle strengthening, and cool down for 30 min. Group 2 performed warm-up, stretching, stabilization, and cool down for 30 min. Group 3 did not receive any intervention. All groups performed round shoulder posture tests, lung capacity tests to determine respiratory function, stroop test, and concentration ability test to determine the concentrations before and after intervention. Results: Significant differences were found in the round shoulder posture on the left between before and after interventions over time (p < 0.05) and between groups (p < 0.05). However, no interaction was observed. The post-hoc test showed that the interventions in group 2 were more effective than those in group 3. A significant difference was noted in the round shoulder posture on the right between before and after intervention over time (p < 0.05). No significant difference and interaction were found between groups. No significant difference was noted in lung capacity. A significant difference in the stroop test (time and number of wrong answers) was found between before and after intervention over time (p < 0.05). No significant difference and interaction were found between the groups. No significant difference was found in the concentration ability test. Conclusion: Our results reveal some evidence that stretching and strengthening exercise causes a decrease in round shoulder posture. However, the intervention period was short and did not allow investigation of the effects on respiratory function and concentration. Continued research on this subject could provide benefits to physiotherapy as it relates to cardiopulmonary treatment.
Eun Kyo Ko,Han Gyeol Lee,Sangmin Lee,Junsik Mun,Jinkwon Kim,Ji Hye Lee,Tae Heon Kim,Jin-Seok Chung,Suk Bum Chung,Miyoung Kim,Seo Hyoung Chang,Tae Won Noh 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1
In the field of oxide heterostructure engineering, there have been extensive efforts to couple the various functionalities of each material. The Berry curvature-driven magnetotransport of SrRuO3 ultrathin films is currently receiving a great deal of attention because it is extremely sensitive to extensive physical parameters. Although this is beneficial in terms of heterostructure engineering, it renders transport behavior vulnerable to nanoscale inhomogeneity, resulting in artifacts called “hump anomalies”. Here, we develop a method to tune the magnetotransport properties of SrRuO3 ultrathin films capped by LaAlO3 layers. We systematically controlled the kinetic process by varying the pressure during LaAlO3 layer deposition and investigated the effects on nanoscale inhomogeneity in SrRuO3 films. We found that the high-kinetic energy of the capping layer adatoms induces stoichiometric modification and nano-scale lattice deformation of the underlying SrRuO3 layer. The control of kinetics provides us a way to modulate magnetization and the associated magnetotransport of the SrRuO3 layer.