• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.19-24
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• 2021

As the size of semiconductor devices decreases, the etching pattern becomes very narrow and a deep high aspect ratio process becomes important. The cryogenic etching process enables high aspect ratio etching by suppressing the chemical reaction of reactive ions on the sidewall while maintaining the process temperature of -100℃. ESC is an important part for temperature control in cryogenic etching equipment. Through the cooling path inside the ESC, liquid nitrogen is used as cooling water to create a cryogenic environment. And since the ESC directly contacts the wafer, it affects the temperature uniformity of the wafer. The temperature uniformity of the wafer is closely related to the yield. In this study, the cooling path was designed and analyzed so that the wafer could have a uniform temperature distribution. The optimal cooling path conditions were obtained through the analysis of the shape of the cooling path and the change in the speed of the coolant. Through this study, by designing ESC with optimal temperature uniformity, it can be expected to maximize wafer yield in mass production and further contribute to miniaturization and high performance of semiconductor devices.

• Journal of Microbiology and Biotechnology
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• v.7 no.5
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• pp.318-322
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• 1997

In order to isolate a microorganism having preferential degradation of D-carnitine from DL-carnitine, a bacterium assimilating D-carnitine as a sole carbon and energy source was isolated from soil by enrichment culture and partially identified as Enterobacter sp. Also, a mutant having lessened L-carnitine decomposition rates was selected with nitrosoguanidine mutagenesis, which led to decrease the specific activities of carnitine dehydrogenase (7.6-fold) and ${\beta}$-hydroxybutyrate dehydrogenase (9.5-fold) as compared to the wild strain. Meanwhile, optimal culture conditions for optical resolution of DL-carnitine were investigated. Under optimal conditions, 3.53 g/l L-carnitine was obtained from 20 g/l DL-carnitine, which corresponded to 35.3% L-carnitine yield and 97.9% optical purity.

• Journal of the Korean Chemical Society
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• v.13 no.2
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• pp.171-175
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• 1969

This study wa attempted to extract the Potash-Ammonia Fertilyzer in most satisfactory yield from the Uncalcinecl Domestic Alunite ore applying an optimal reaction conditions (Ammonia water concentration and applicable reaction pressure, etc.), it was found that almost all amount of $K_2SO_4$ was extracted in the forms of $K_2SO_4·(NH_4)_2SO_4$mixture under such conditions. The experimental data to note are as follows: 1. The optimal pressure applied to the reaction was 600 to 700 Psig. 2. The optimal concentration of Ammonia water was 7 Mol/L. 3. The reaction time needed was 3 hours. 4. The extraction rate and degree were not at variance with sorts and occurrences of Alunite ore.

• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.601-605
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• 1998

For the resolution of L-carnitine from DL-carnitine, resting cells of Enterobacter sp. NH-104, which had a higher capacity of D-carnitine decomposition, were harvested at maximal specific activity of D-carnitine decomposition of 47.05 unit/mg cell. The cells were frozen at $-80^{\circ}C$ to assess functions as enzyme sources. Optimal concentration of cells and DL-carnitine were 17 g/$\ell \; and \; 20 g/\ell$, respectively, and reaction buffer was best at 75 mM of Tris. HCl. Optimal temperature and pH were $36^{\circ}C$ and 8.2, respectively. When the reaction at optimal conditions was carried out for 14 h, the optical purity was 98.21 %, and the quantity and yield of remaining L-carnitine were 4.432 g/$\ell$ and 44.32%, respectively.

• Journal of Microbiology and Biotechnology
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• v.12 no.3
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• pp.360-366
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• 2002

Central composite experimental design was employed to determine the optimal concentration of medium constituents for griseofulvin production by Penicillium griseofulvum MTCC 1898 and Penicillium griseofulvum MTCC 2004. The optimal concentration of sucrose, $K_2HPO_4,\;NaNO_3,\;and\;FeSO_4{\cdot}7H_2O$ were found to be 48.08 g/1, 1.228 g/1 , 2.7 g/1, and 0.011 g/1, respectively, for Penicillium griseofulvum MTCC 1898, and for Penicillium griseofulvum MTCC 2004, 23.52 g/1, 43.67 g/1, and 0.0434 g/1 of glucose, lactose, and $MnSO_4{\cdot}H_2O$, respectively. The yield of griseofulvin under optimal composition of medium constituents increased by 1.26 and 1.38 times than prior to optimization, for Penicillium griseofulvum MTCC 1898 and Penicillium griseofulvutn MTCC 2004, respectively.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.267-270
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• 1997

To industrialize the foods using wormwood extract, the optimal extraction yield of growth-inhibitory component of wormwood (Artemisia princeps) against Clostridium perfringens in vitro was investigated at various conditions. The optimal extraction of wormwood was produced from the condition of $40^{\circ}C$, 4 hours and 100% ethanol (30 volume).

• Korean Journal of Computational Design and Engineering
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• v.5 no.3
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• pp.263-275
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• 2000

Multidisciplinary design optimization(MDO) can yield optimal design considering all the disciplinary requirements concurrently. A method to implement the collaborative optimization(CO) approach, one of the MDO methodologies, is developed using a pre-compiler “EzpreCompiler”, a design optimization library “EzOptimizer”, and a common object request broker architecture(CORBA) in distributed computing environment. The CO approach is applied to a mathematical example to show its applicability and equivalence to standard optimization(SO) formulation. In a realistic engineering problem such as optimal design of a two-member hub frame, optimal design of a speed reducer and initial design of a bulk carrier, the CO yields better results than the SO. Furthermore, the CO allows the distributed processing using the CORBA, which leads to reduction of overall computation time.

• Environmental Engineering Research
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• v.20 no.2
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• pp.121-125
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• 2015

Biohydrogen production from food waste via dark fermentation was conducted by using mixed culture under various environmental conditions (initial pH, initial F/M ratio, initial ferrous iron ($Fe^{2+}$), and temperature condition) in batch reactor. The results revealed that the maximum hydrogen yield of $46.19mL\;H_2/g\;COD_{add}$ was achieved at the optimal conditions (initial pH 8.0, initial F/M ratio 4.0, initial iron concentration 100 mg $FeSO_4/L$ and thermophilic condition ($55{\pm}1^{\circ}C$)). Furthermore, major volatile fatty acid (VFA) productions of butyrate (765.66 mg/L) and acetate (324.69 mg/L) were detected and COD removal efficiency was detected at 66.00%. Therefore, these optimal conditions could be recommended to operate a system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.04a
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• pp.93-96
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• 2009

The high grade thick plate is in great demand in the ship building industry and the construction industry. The main problems to produce the high grade plate are residual stress and flatness of plate. In the previous research, Finite Element Analysis(FEA) was conducted for cold roller leveler to understand the behaviors of cold roller leveler under different conditions of thickness, intermesh, and yield stress. In this study, a numerical model of roller leveler is developed and the calculated results of this model are compared with the FEA results to show the validity of the numerical model. The optimal leveling conditions to improve flatness of plate are suggested using this numerical model.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.571-579
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• 1990

A dynamic relocation algorithm for non-deterministic process graph in distributed computer systems is proposed. A method is represented for determining the optimal policy for processing a process tree. A general database query request is modelled by a process tree which represent a set of subprocesses together with their precedence relationship. The process allocation model is based on operating cost which is a function fo selection of site for processing operation, data reduction function and file size. By using expected values of parameters for non-deterministic process tree, the process graph and optimal policy that yield minimum operating cost are determined. As process is relocated according to threshold value and new information of parameters after the execution of low level process for non-deterministic process graph, the assigned state that approximate to optiaml solution is obtained. The proposed algorihtm is heuristic By performing algorithm for sample problems, it is shown that the proposed algorithm is good in obtaining optimal solution.