• The Korean Journal of Nuclear Medicine Technology
• /
• v.15 no.2
• /
• pp.72-75
• /
• 2011

Purpose: The HSV1-tk reporter gene system is the most widely used system because of its advantage is that it is possible to monitor directly without the introduction of a separate reporter gene in case of HSV1-tk suicide gene therapy. This study was performed to automate 9-(4-[$^{18}F$] Fluoro-3-hydroxymethylbutyl) guanine ([$^{18}F$] FHBG) that are widely used as substrate for the HSV1-tk reporter gene in living organisms with positron emission tomography (PET) and find the optimized conditions of synthesis. Materials and Methods: Fully automated synthesis of [$^{18}F$] FHBG was performed using Explora-RN (CTI, USA) module. We have changed of reaction time (3, 5, 10 min) and temperature (110, 120, $130^{\circ}C$) for the optimized conditions of synthesis. Also we experimented to find the optimal concentration of precursor (5, 7, 10 mg). Results: [$^{18}F$] FHBG was purified by HPLC system and collected at around 10-12 min. Synthesis using Explora-RN module showed a $32.0{\pm}1.2%$ yield of radiochemical (decay corrected), the purity was greater than 98%. And the entire synthesis time was less than 48 min. Temperature of the highest synthesis yield was $130^{\circ}C$, reaction time was 5 minutes and concentration of precursor was 10 mg (recommended volume in manual) (n=36). In contrast to radiochemical yield of precursor 10 mg ($32{\pm}1.2%$), yield of 5 and 7 mg precursor was unstable. Conclusion: Automation of [$^{18}F$] FHBG synthesis at Explora-RN module has been completed. In addition, we were able to obtain optimized reaction time, temperature and concentration of precursor. Therefore this study would be provided more rapid synthesis and higher radiochemical yield.

• Korean Chemical Engineering Research
• /
• v.47 no.6
• /
• pp.700-704
• /
• 2009

A simulation study on SCR(steam carbon dioxide reforming) in gas-to-liquid(natural gas to Fischer-Tropsch synthetic fuel) process was carried out in order to find optimum reaction conditions for SCR experiment. Optimum operating conditions for SCR process were determined by changing reaction variables such as temperature and $CH_4/steam/CO_2$ feed ratio. Simulation was carried out by Aspen Plus. During the simulation, overall process was assumed to proceed under steady-state conditions. It was also assumed that physical properties of reaction medium were governed by RKS(Redlich-Kwong-Soave) equation. Optimum simulation variables such as temperature and feed ratio were determined by considering $H_2/CO$ ratio for FTS(Fischer-Tropsch synthesis), $CH_4$ conversion, and $CO_2$ conversion. Simulation results showed that optimum reaction temperature and $CH_4/steam/CO_2$ feed ratio in SCR process were $850^{\circ}C$ and 1.0/1.6/0.7, respectively. Under optimum temperature of $850^{\circ}C$, $CH_4$ conversion and $CO_2$ conversion were found to be 99% and 49%, respectively.

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.1
• /
• pp.99-106
• /
• 2021

To circumvent the skin problem from phenylethanol (PhE), we have studied on the enzymatic synthesis of phenylethanol galactoside (PhE-gal) as an alternative to PhE. Base on the previous study, we optimized the reaction conditions for PhE-gal synthesis from PhE using E. coli β-galactosidase (β-gal). The optimal amount of β-gal, PhE concentration, pH, and temperature for PhE-gal synthesis were 0.45 U/ml, 1%, 8.0, 40℃, respectively. Under these conditions, about 81.9 mM PhE was converted into about 47.4 mM PhE-gal, in which the conversion yield was about 57.9%. Meanwhile, when the reaction mixture containing PhE and PhE-gal was mixed and fractionated with water-immiscible solvent (EA or MC), it was observed that PhE-gal was distributed in water phase, and PhE was distributed in solvent phase. Additionally, PhE-gal was clearly distributed into water phase when MC was used, but PE-gal was not when EA was used. In the future, we are planning to carried out the continuing study on developing an alternative cosmetic preservative using PhE-gal.

• Korean Journal of Clinical Laboratory Science
• /
• v.55 no.4
• /
• pp.261-268
• /
• 2023

[¹⁸F]Fluorocholine is a radiopharmaceutical used non-invasively in positron emission tomography to diagnose parathyroid adenoma, prostate cancer, and hepatocellular carcinoma by evaluating the choline metabolism. In this study, a radiolabeling method for [¹⁸F]fluorocholine was optimized using a solid phase extraction (SPE) cartridge. [¹⁸F]Fluorocholine was labeled in two steps using an automated synthesizer. In the first step, dibromomethane was reacted with [¹⁸F]KF/K2.2.2/K₂CO₃ to obtain the intermediate [¹⁸F]fluorobromomethane. In the second step, [¹⁸F]fluorobromomethane was passed through a Sep-Pak^Ⓡ Silica SPE cartridge to remove the impurities and then reacted with N,N-dimethylaminoethanol (DMAE) in a Sep-Pak^Ⓡ C18 SPE cartridge to label [¹⁸F]fluorocholine. The reaction conditions of [¹⁸F]fluorocholine were optimized. The synthesis yield was confirmed according to the number of silica cartridges and DMAE concentration. No statistically significant difference in the synthesis yield of [¹⁸F]fluorocholine was observed when using four or three silica cartridges (P>0.05). The labeling yield was 11.5±0.5% (N=4) when DMAE was used as its original solution. On the other hand, when diluted to 10% with dimethyl sulfoxide, the radiochemical yield increased significantly to 30.1±5.2% (N=20). In conclusion, [¹⁸F]Fluorocholine for clinical use can be synthesized stably in high yield by applying an optimized synthesis method.

• Applied Chemistry for Engineering
• /
• v.30 no.4
• /
• pp.421-428
• /
• 2019

This paper describes a methode to extract yellow pigment from curcuma and turmeric containing natural color curcumin whose target color indexes of L, a, and b were 87.0 7.43, and 88.2, respectively. The pH range and extraction temperature used for the reaction surface analysis method were from pH 3 to pH 7 and between 40 and $70^{\circ}C$, respectively for both natural products. A central synthesis planning model combined with the method was used to obtain optimal extraction conditions to produce the color close to target. Results and regression equations show that the color space and difference of curcuma and turmeric have the greatest influence on the value. In the case of curcuma, the optimum conditions to satisfy all of the response theoretical values of color coordinates of L (74.67), a (5.69), and b (70.08) were at the pH and temperature of 3.43 and $54.8^{\circ}C$, respectively. The experimentally obtained L, a, and b, values under optimal conditions were 72.92, 5.32, and 72.17, respectively. For the case of turmeric, theoretical numerical color coordinates of L, a, and b, under the pH of 5.22 and temperature of $50.4^{\circ}C$ were 82.02, 7.43, and 72.86 respectively. Whereas, the experiment results were L (81.85), a (5.39), and b (71.58). Both cases showed an error range within 1%. Therefore, it is possible to obtain a low error rate when applying the central synthesis planning model to the reaction surface analysis method as an optimization process of the dye extraction of natural raw materials.

• Journal of KIISE:Software and Applications
• /
• v.27 no.5
• /
• pp.463-472
• /
• 2000

In this paper, we consider the problem of realizing associative memories via cellular neural network(CNN). After introducing qualitative properties of the CNN model, we formulate the synthesis of CNN that can store given binary vectors with optimal performance as a constrained optimization problem. Next, we observe that this problem's constraints can be transformed into simple inequalities involving linear matrix inequalities(LMIs). Finally, we reformulate the synthesis problem as a generalized eigenvalue problem(GEVP), which can be efficiently solved by recently developed interior point methods. Proposed method can be applied to both space varying template CNNs and space-invariant template CNNs. The validity of the proposed approach is illustrated by design examples.

• Applied Chemistry for Engineering
• /
• v.26 no.3
• /
• pp.377-380
• /
• 2015

In this paper, we have investigated the optimization of $I_2$ recovery process from $NH_4I$ solution, which is generated as by-product during the amination reaction of p-diiodobenzene (PDIB) for p-phenylenediamine (PPD) synthesis. The recovered $I_2$ is then recycled as a raw material for PDIB synthesis. We have employed a cation exchange resin to recover $I_2$ from $NH_4I$ sample solution, and determined the breakthrough point and exchange capacity from the breakthrough curve. Furthermore, we have suggested optimum conditions of our $I_2$ recovery process by measuring the purity and yield of recovered $I_2$ with respect to the concentrations of $NH_4I$ and oxidant ($H_2O_2$) solutions, the oxidation time, and the temperature of drying process. Finally, the yield and purity as high as 94.96% and 96.65%, respectively were obtained by reusing the residual solution still containing unrecovered iodide ions.

• Journal of the Korean Ceramic Society
• /
• v.41 no.9
• /
• pp.670-676
• /
• 2004

The synthesis of highly concentrated silver nano sol assisted by polymeric dispersant (polyelectrolytes) for inkjet method was studied. The silver nano sol was prepared with AgNO$_3$, polyelectrolytes (HS5468cf ; polyacrylic ammonium salt), and reducing agent. The polyelectrolytes play an important role in formation of complex composed of Ag$\^$+/ion and carboxyl group (COO$\^$-/), result in preparation of highly dispersed silver nano particles. The optimization of added amount of polyelectrolytes, and concentration of silver nano sol was studied. The silver nanoparticles were evaluated by XRD, particle size/zeta potential analyzer and FE-TEM. The silver nanoparticles with the range of 10 nm in diameter were produced. The concentration of batch-synthesized silver nano sol was possible up to 40 wt%.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.652-652
• /
• 2013

The conventional thermal chemical vapor deposition (CVD) setup for the graphene synthesis has mainly used convective heat transfer in order to heat a catalyst (e.g. Cu) up to $1,000^{\circ}C$. Although the conventional CVD has been so far widely accepted as the most appropriate candidate enabling mass-production of high-quality graphene, this method has stillremained under the standard for the commercialization largely due to the poor productivity arisen out of the required long processing time. Here, we introduced a fast and efficient synthetic route toward CVD-graphene. Unlike the conventional CVD using convection heat transfer, we adopted a CVD setup utilizing conduction heat transfer between Cu catalyst and rapid heating source. The high thermal conductive nature of Cu and the employed rapid heating source led to the remarkable reduction in processing timeas compared to the conventional convection based CVD (Fig. 1A), moreover, the synthesized graphene was turned out to have comparable quality to that synthesized by the conventional CVD (Fig. 1B). For the optimization of the conduction based CVD process, the parametric studies were thoroughly performed using through Raman spectroscopy and electrical sheet resistance measurement. Our approach is thought to be worth considerable in order to enhance productivity of the CVD graphene in the industry.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.2 no.1
• /
• pp.38-60
• /
• 1999

The main objective of this study is systemization of the technique of ROC quantification and optimization of baseline design by applying CE principle to the acquisition process of a weapon system. QFD and TOA techniques can be employed to a good working example of the conceptual design of a future main battle tank. In this paper, Product Planning Phase, the first phase of four QFD phases, is deployed in terms of eight steps including customer requirements and final product control characteristics. TOA is carried out considering only combat weight. In order to perform combat weight analysis and performance TOA, Preliminary Configuration Synthesis Methodology is used. Preliminary Configuration Synthesis Methodology employs the method of least squares and described linear equations of weight interrelation equation for each component of tank. As a result of QFD based upon the ROC, it was cleared that armor piercing power, main armament, type of ammunition, cruising range, combat weight, armor protection, power loading, threat detection and cost are primary factors influencing design and that combat weight is the most dominant one. The results of TOA based on the combat weight constraint show that 5100 lb reduction was required to satisfy the ROC. The baseline design of a future main battle tank is illustrated with assumption that all phases of QFD are employed to development and production process of subsystems, components, and parts of main battle tank. TOA is applied in iterative process between initial baseline design and ROC. The detailed design of each component is illustrated for a future main battle tank.