• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.615-621
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• 2013

Solvolyses of isobutyl chloroformate (4) in 43 binary solvent mixtures including highly aqueous media, water, $D_2O$, $CH_3OD$, 2,2,2-trifluoroethanol (TFE) as well as aqueous 1,1,1,3,3,3-hexafluoro-isopropanol (HFIP) solvents were performed at $45^{\circ}C$, in order to further investigate the recent results of D'Souza, M. $J^1$. et al.; solvolyses of 4 are found to be consistent with the proposed mechanism ($Ad_E$). The variety of solvent systems was extended to comprise highly ionizing power solvent media ($Y_{Cl}$ > 2.7 excepted for aqueous fluorinated solvents and pure TFE solvent) to investigate whether a mechanistic change occurs as solvent compositions are varied. However, in case of 18-solvent ranges having aqueous fluorinated solvent systems (TFE-$H_2O$ and HFIP-$H_2O$) and/or having $Y_{Cl}$ > 2.7 solvent systems, the solvent effect on reactivity for those of 4 are evaluated by the multiple regression analysis as competition with $S_N2$ - type mechanism. And in pure TFE and 97 w/w % HFIP solvents with high $Y_{Cl}$ and weak $N_T$, these solvolyses are understood as reactions which proceed through an ionization ($S_N1$) pathway.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.5
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• pp.597-607
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• 2014

This paper proposes active power control and frequency support control schemes of wind turbine generation system by using modified Maximum Power Point Tracking(MPPT) of Permanent Magnet Synchronous Generator(PMSG). Most wind turbine generation system is completely decoupled from the power system and power output control with pitch control. According to the frequency deviation, however, MPPT control can not contribute to the frequency change of the power system due to its active power output control. For solving this, the de-loaded(DL) control scheme is constructed for the frequency support control, which is based on applying the active power output control in the rotor speed control of PMSG. The rotor speed by used in the proposed DL control scheme is increased more than the optimal rotor speed of MPPT, and then this speed improvement increases the saved kinetic energy(KE). In order to show the effectiveness of the proposed control scheme, the case studies have been performed using the PSCAD/EMTDC. The results show that the proposed active power output control scheme(DL control and KE discharge control) works properly and the frequency response ability of the power system can be also improved with the frequency support of wind farm.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1758-1766
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• 2012

An extensive investigation was carried out to describe the kinetics of cell growth, substrate consumption, and product formation in the batch fermentation using starch as substrate. Evaluation of intrinsic kinetic parameters was carried out using a best-fit unstructured model. A nonlinear regression technique was applied for computational purpose. The Andrew's model showed a comparatively better $R^2$ value among all tested models. The values of specific growth rate (${\mu}_{max}$), saturation constant ($K_S$), inhibition constant ($K_I$), and $Y_{X/S}$ were found to be 0.109 $h^{-1}$, 11.1 g/l, 0.012 g/l, and 1.003, respectively. The Leudeking-Piret model was used to study the product formation kinetics and the process was found to be growth-associated. The growth-associated constant (${\alpha}$) for protease production was sensitive to substrate concentration. Its value was fairly constant up to a substrate concentration of 30.8 g/l, and then decreased.

• Environmental Engineering Research
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• v.19 no.3
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• pp.185-195
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• 2014

Despite the enormous technical and economic efforts to improve environmental conditions, currently about 40% of the global population (or 2 billion people) are still lack access to safe water supply and adequate sanitation facilities. Pollution problems and transmission of water- related diseases will continue to proliferate. The rapid population growth and industrialization will lead to a reduction of arable land, thus exacerbating the food shortage problems and threatening environmental sustainability. Natural systems in this context are a transdisciplinary approach which employs the activities of microbes, soil and/or plants in waste stabilisation and resource recovery without the aid of mechanical or energy-intensive equipments. Examples of these natural systems are: waste stabilisation ponds, aquatic weed ponds, constructed wetlands and land treatment processes. Although they require relatively large land areas, the natural systems could achieve a high degree of waste stabilisation and at the same time, yield potentials for waste recycling through the production of algal protein, fish, crops, and plant biomass. Because of the complex interactions occurring in the natural systems, the existing design procedures are based mainly on empirical or field experience approaches. An integrated kinetic model encompassing the activities of both suspended and biofilm bacteria and some important engineering parameters has been developed which could predict the organic matter degradation in the natural systems satisfactorily.

• Journal of Power System Engineering
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• v.2 no.1
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• pp.31-38
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• 1998

A diffuser, an important equipment to change kinetic energy into pressure energy, has been studied for a long time. Though experimental and theoretical researches have been done, the understanding of energy transfer and detailed mechanism of energy dissipation is unclear. As far as numerical prediction of diffuser flows are concerned, various numerical studies have also been done. On the contrary, many turbulence models have constraint to the applicability of diffuser-like complex flows, because of anisotropy of turbulence near the wall and of local nonequilibrium induced by an adverse pressure gradient. The existing $k-{\epsilon}$ turbulence models have some problems in the case of being applied to complex turbulent flows. The purpose of this paper is to test the applicability of the nonlinear $k-{\epsilon}$ model concerning diffuser-like flows with expansion and streamline curvature. The results show that the nonlinear $k-{\epsilon}$ turbulence model predicted well the coefficient of pressure, velocity profiles and turbulent kinetic energy distributions, however the shear stress prediction was failed.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.408-414
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• 1987

The rate of bromine-exchange reaction between antimony tribromide and ${\alpha}-phenyl-n-butyl$ bromide in nitrobenzene has been determined, using antimony tribromide labelled with Br-82. The results indicate that the exchange reaction follows the first-order kinetics with respect to the organic bromide, and either the second- or first-order kinetics with respect to antimony tribromide depending on its concentration. The third-order rate constant obtained was 7.50 ${\times}10^{-2}l^2mol^{-2}s^{-1}$ at 28$^{\circ}$C. Similar study on the bromine-exchange reaction between antimony tribromide and ${\alpha}$-phenyl-i-butyl bromide has also been carried out. The results of the study show the same kinetic orders as the ones observed with $\alpha$-phenyl-n-butyl bromide. The third-order rate constant observed was 2.40 ${\times} 10^{-2} l^2mol^{-2}s^{-1}$ at 28$^{\circ}$C. The activation energy, the enthalpy of activation and the entropy of activation for the two exchange reactions mentioned above have been determined. The reaction mechanisms for the exchange reactions are discussed.

• Bulletin of the Korean Chemical Society
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• v.14 no.5
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• pp.621-625
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• 1993

Kinetic studies are conducted for the reactions of Y-benzoyl, Y-benzenesulfonyl and Y-benzyl halides with X-anilines in acetonitrile, and the transition state (TS) structures and their variations with substituents X and Y are discussed. The magnitude of the cross-interaction constants, $\rho$xy, is the largest and the inverse secondary kinetic isotope effect (SKIE), $k_H/k_D$ < 1.0, with deuterated aniline nucleophiles is the smallest for benzoyl fluoride reflecting the tightest TS for this compound. The SKIEs for sulfonyl halides are relatively large due to a relatively large, diffuse nature of the reaction center, S, causing weaker steric hindrance to the vibrations of the two N-H(D) bonds. For benzoyl and sulfonyl halides, the trends in $k_H/k_D$ and $Ir_XI$ variations with $\sigma$Y contradict each other, which is rationalized by the negative charge accumulation on the reaction center, CO and SO$_2$, causing inefficient transfer for the substrate with an electron donating substituent.

• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.562-568
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• 2019

Cylindrical shape extrudates of calcium silicate hydrate (CSH) were prepared using different percentages of polyvinyl alcohol (PVA) / sodium alginate (SA) mixtures as binders and an aqueous solution containing 6% $H_3BO_3$ and 3% $CaCl_2$ was used as a cross linking agent. As the quantity of alginate increases, the phosphate removal efficiency and capacity were decreased. Among four different extrudate samples, the sample prepared by 8% PVA + 2% SA showed the highest phosphate removal efficiency (59.59%) and capacity (29.97 mg/g) at an initial phosphate concentration of 100 ppm and 2.0 g/L adsorbent dosage. Effects of the adsorbent dosage, contact time and initial phosphate concentration on the sample were further studied. The removal efficiency and capacity obtained by a 4.0 g/L adsorbent dose at an initial phosphate concentration of 100 ppm in 3 h were 79.38% and 19.96 mg/g, respectively. The experimental data of kinetic and isotherm measurements followed the pseudo-second-order kinetic equation and Langmuir isotherm model, respectively. These results suggested that the phosphate removal was processed via a chemisorption and a monolayer coverage of phosphate anions was on the CSH surface. The maximum adsorption capacity ($q_{max}$) was calculated as 23.87 mg/g from Langmuir isotherm model.

• The Journal of Korean Physical Therapy
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• v.31 no.4
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• pp.161-168
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• 2019

Most athletes with anterior cruciate ligament (ACL) ruptures undergo a surgical ACL reconstruction (ACLR) and rehabilitation. On the other hand, controversy still exists because neither a reconstruction nor rehabilitation have been proven to be superior in the management of ACL injury. This study reviewed the success rates of interventions to provide recommendations for the optimal management after an ACL injury. One of the most important considerations after an ACL injury is the timing and type of intervention. At the early stages, which involve the loss of volume and strength of quadriceps femoral muscle, weight bearing (closed kinetic chain) exercises with pain management followed by high velocity resistance exercises in an open kinetic chain environment are recommended to improve the quadriceps function. After that, it is important to apply intensive isokinetic exercise with a lower extension rate. In this case, it is important to apply overload to the muscles and to simultaneously lead the co-contraction of the hamstrings. Standards are essential because the timing and type of interventions are crucial to prevent re-injury and complications, such as osteoarthritis, as well as to confirm the successful outcome of the treatment. Different interventions recommended for ACL damage have yet to reach consensus. Further studies will be needed to observe the effects of the intervention through multidisciplinary approaches.

• Archives of Plastic Surgery
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• v.49 no.1
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• pp.19-24
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• 2022

Background Blepharoplasty has both aesthetic and functional benefits in patients with pseudoptosis; however, previous studies could not demonstrate its beneficial effects quantitatively and objectively. The authors objectively analyzed the visual field before and after surgery and investigated whether measurements of the visual field can be applied as a suitable predictor of surgical outcomes. Methods In total, 18 eyelids in nine patients with pseudoptosis who had undergone simple skin excision blepharoplasty were evaluated prospectively from February to May 2016. The visual fields were analyzed preoperatively and 3 months postoperatively using the Goldmann kinetic perimetry test. The visual field test area was assessed using Adobe Photoshop. Results Blepharoplasty had an average 4.99-fold beneficial effect on the superior visual field. In particular, more improvement was seen in the superior temporal quadrant than in the nasal quadrant. No correlation was found between the preoperative margin-to-reflex distance 1 (MRD1) and the surgical outcome (P=0.119). However, there was a strong correlation between the preoperative superior visual field and the surgical outcome (P=0.001). Conclusions Using the Goldmann kinetic perimetry test, we objectively and quantitatively proved the beneficial effect of blepharoplasty on patients with pseudoptosis. Furthermore, we demonstrated that the preoperative visual field is a better preoperative surgical outcome predictive factor than the preoperative MRD1.