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Dae Ryook Yang,Seungjong Yeom,Huichan Yun 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.10
L-glutamic acid can be crystallized as metastable α-form and stable β-form crystal. The α-form is desired because of its prismatic shape. Production of α-form of L-glutamic acid by cooling crystallization is not well-defined and α-form solid is commercially not available. In this study, an optimal cooling strategy to selectively produce large and narrowly distributed α-crystals is found by modeling and optimizing the crystallization and polymorphic transformation of L-glutamic acid. The optimal temperature profile is found to be cooling-heating-cooling concept where short nucleation period is followed by growth period in metastable zone. The obtained α-form of L-glutamic acid by optimal strategy had improved mean size, distribution, and purity compared to constant cooling.
Improving Dynamics of Glass pH Electrodes
Dae Ryook Yang,Seungjae Lee,Su Whan Sung,Jietae Lee IEEE 2009 IEEE Sensors Journal Vol.9 No.12
<P>The glass pH electrode has a very large internal resistance and an internal capacitance, exhibiting a relatively large response time. For some applications, the response time needs be shortened. For this purpose, a method to reduce the response time of glass pH electrodes and to diagnose its performance is proposed.</P>
Jung, Heon,Yang, Dae-Ryook,Joo, Oh-Shim,Jung, Kwang-Deog Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.5
Ternary Cu/ZnO/$Al_2O_3$ catalysts were prepared by a co-precipitation method. The precursor structures were monitored during the aging. The first precipitate structure was amorphous georgeite, which transformed into the unknown crystalline structure. The transition crystalline structure was assigned to the crystalline georgeite, which was suggested with elemental analysis, IR and XRD. The final structure of precursors was malachite. The Cu surface area of the resulting Cu/ZnO/$Al_2O_3$ was maximized to be 30.6 $m^2$/g at the aging time of 36 h. The further aging rapidly decreased Cu surface areas of Cu/ZnO/$Al_2O_3$. ZnO characteristic peaks in oxide samples almost disappeared after 24 h aging, indicating that ZnO was dispersed in around bulk CuO. TOF of the prepared catalysts of the Cu surface area ranges from 13.0 to 30.6 $m^2/g_{cat}$ was to be 2.67 ${\pm}$ 0.27 mmol/$m^2$.h in methanol synthesis at the condition of $250^{\circ}C$, 50 atm and 12,000 mL/$g_{cat}$. h irrespective of the XRD and TPR patterns of CuO and ZnO structure in CuO/ZnO/$Al_2O_3$. The pH of the precipitate solution during the aging time can be maintained at 7 by $CO_2$ bubbling into the precipitate solution. Then, the decrease of Cu surface area by a long aging time can be prevented and minimize the aging time to get the highest Cu surface area.
역삼투 해수담수화 플랜트의 에너지 소모를 줄이기 위한 실 데이터 분석
홍승관,김정빈,박기호,Dae Ryook Yang 한국막학회 2018 한국막학회 총회 및 학술발표회 Vol.2018 No.11
본 연구는 역삼투 해수담수화 플랜트의 실 데이터 분석을 통해 에너지 소모를 줄이는 방안을 제안한다. 이를 위해 10,000m3/d 이상의 플랜트를 대상으로 70여개의 데이터를 수집하고 분석하였다. 역삼투 해수담수화 플랜트의 에너지 소모는 에너지회수장치 발전으로 인해 크게 감소하였으나 각 요인에 따라 다른 값을 보였다. 에너지 소모는 유입수 수질에 영향을 받고, 높은 수질의 생산수를 얻기 위해선 더 많은 에너지가 소모됨을 확인하였다. 또한, 플랜트 규모가 커지면 에너지 소모가 줄어든다고 알려져 있으나 반드시 그런 것은 아니며, 역삼투시스템 운영 시 에너지 소모가 최소가 되는 회수율이 있음을 알아냈다. 마지막으로 에너지 소모와 관련된 요인을 정리하고 이를 바탕으로 저에너지 소모를 위한 3가지 방안을 제시한다.
Dae Sung Lee,Dae Ryook Yang,In-Beum Lee,Kun Soo Chang 대한전자공학회 1992 대한전자공학회 학술대회 Vol.1992 No.10
In order to achieve stable and efficient use of energy at iron and steel works, a model for the prediction of supply and demand of electric power system is developed on the basis of the information on operation and particular patterns of electric power consumption. The optimal amount of electric power to be purchased and the optimal fuel allocation for the in-house electric power plants are also obtained by a mixed-integer linear programming(MILP) and a nonlinear programming(NLP) solutions, respectively. The validity and the effectiveness of the proposed model are investigated by several illustrative examples. The simulation results show the satisfactory energy saving by the optimal solution obtained through this reseach.
Sang Yeol Lee,Dae Ryook Yang,Ji Woong Chang 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-
The solubility of isosorbide in ethylene glycol was measured and the crystallization kinetic parameterswere estimated via seeded batch cooling crystallization. The saturation concentration of isosorbide wasmeasured using a density meter, which enabled rapid and accurate measurement of the concentration. The crystallization kinetic parameters were estimated byfitting the population balance equation to thetime-dependent change of concentration and average crystal size. Crystallization using continuousstirred tank reactors (CSTR) was simulated with the obtained parameters, and the reliability of thesimulation was verified with experiments. The kinetic parameters estimated from seeded batchcrystallization experiments can be used for the prediction of crystallization under seeded conditions,such as CSTR. The prediction of the crystal size and concentration of the CSTR crystallizer using theestimated parameters were consistent with the experimental results. The amount and composition ofresidue obtained from industrial poly(ethylene-co-isosorbide) terephthalate process was predicted, andrecovery processes and optimum operating conditions are proposed via simulation using Aspen Plus.
CCL4 DECOMPOSITION BY GLIDING ARC PLASMA: ROLE OF C2 COMPOUNDS ON PRODUCTS DISTRIBUTION
Indarto, Antonius,Yang, Dae Ryook,Choi, Jae-Wook,Lee, Hwaung,Song, Hyung Keun Taylor Francis 2007 Chemical engineering communications Vol.194 No.8
<P> The goal of this work is to investigate the role of existing C2 compounds in the plasma reactions of carbon tetrachloride (CCl4) decomposition. The experiment of CCl4 decomposition was carried out by gliding arc plasma. The decomposition products were dominated by CO, CO2, and Cl2. The conversion of CCl4 into Cl2 and (CO + CO2) reaches ∼ 50% and ∼ 40%, respectively. Other chlorinated compounds were suspected to be produced, such as COCl, COCl2, and C2 compounds. In order to prove the existence of those compounds, for example, chlorinated C2 compounds, a kinetic simulation was performed and cross-checked with the experimental results to clarify the reactions mechanism.</P>