• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.213-222
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• 2016

Solubility data of hydrogen sulfide ($H_2S$) and methane ($CH_4$) in two kinds of ionic liquids with the same anion: 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][TfO]) and 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ([bmpyr][TfO]) are presented at pressures up to about 30 MPa and at temperatures between 303 K and 343 K. The gas solubilities in ionic liquids were determined by measuring the bubble point pressures of the gas + ionic liquid mixtures with various compositions at different temperatures using a high-pressure equilibrium apparatus equipped with a variable-volume view cell. The $H_2S$ solubilities in ionic liquid increased with the increase of pressure and decreased with the increase of temperature. On the other hand, the $CH_4$ solubilities in ionic liquid increased significantly with the increase of pressure, but there was little effect of temperature on the $CH_4$ solubility. For the ionic liquds [emim][TfO] and [bmpyr][TfO] with the same anion, the solubility of $H_2S$ as a molality basis was substantially similar, regardless of the temperature and pressure conditions as a molar concentration basis. Comparing the solubilities of $H_2S$ and $CH_4$ in the ionic liquid [emim][TfO], the solubilities of $H_2S$ were much greater than those of $CH_4$. For the same type of ionic liquid, the solubility data of $H_2S$ and $CH_4$ obtained in this study were compared to the solubility data of $CO_2$ from the literature. When compared at the same pressure and temperature conditions, the $CO_2$ solubility was in between the solubility of $H_2S$ and $CH_4$.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.275-282
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• 2010

A characteristic study of aqueous chlorine dioxide generation from sodium chlorite($NaClO_2$) by an undivided electrochemical cell with different anode materials were performed. $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA were used as anode materials and Pt-coated Ti electrode was used as cathode. Various electrochemical cell operating parameters such as cell residence time($t_R$), initial feed solution pH, sodium chlorite and sodium chloride(NaCl) concentration and applied current for the generation of chlorine dioxide in an un-divided cell were investigated and optimized. Estimated optimal cell residence times in $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode material systems were around 2.27, 1.52 and 1.52 sec, respectively. Observed optimum initial feed solution pH was around 2.3 in all anode material systems. Optimum sodium chlorite concentrations in $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode systems were around 0.43, 0.43 and 0.32 g/L, respectively. Optimum electrolyte concentration and applied current were around 5.85 g/L and 0.6 A in all anode systems. Current efficiencies of $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode systems under optimum conditions were 79.80, 114.70 and 70.99%, respectively. Obtained energy consumptions for the optimum generation of chlorine dioxide were 1.38, 1.03 and $1.61W{\cdot}hr/g-ClO_2$, respectively.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.261-268
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• 2018

To prepare mesoporous $TiO_2$ ($meso-TiO_2$) with anatase and rutile crystal structures, hydrothermal and template synthesis were used. $Meso-TiO_2$ with anatase structure was obtained by hydrothermal synthesis. The crystal structure of $meso-TiO_2$ by hydrothermal synthesis converted from anatase to rutile by simple heating at $600^{\circ}C$ and above. However, their mesopore structure collapsed due to phase transition. To prepare $meso-TiO_2$ with rutile structure, template synthesis method was applied using mesoporous silica KIT-6 as a template. Once we incorporated anatase $TiO_2$ inside mesopores of silica, the phase transition temperature of $TiO_2$ confined inside KIT-6 was much higher ($900^{\circ}C$) than that of free-standing $TiO_2$ ($600^{\circ}C$). The suppression of $TiO_2$ phase transition inside mesopores of KIT-6 is closely related with the interaction between $TiO_2$ surface and silica walls in KIT-6 because oxygen vacancy in $TiO_2$ is regarded as the starting point for phase transition. After removal of silica template by NaOH solution washing, $meso-TiO_2$ with mixed phase between anatase and rutile was obtained.

• Journal of the Korean Electrochemical Society
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• v.8 no.3
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• pp.139-145
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• 2005

[ $SnO_x$ ] films on the flexible substrate of PET film were prepared at ambient temperature under a $(CH_3)_4Sn(TMT: tetra-methyl tin)-H_2-O_2$ atmosphere in order to obtain transparent conductive polymer by using ECR-MOCVD(Electro Cyclotron Resonance Metal Organic Chemical Yfpor Deposition) system. The prepared $SnO_x$ thin films show generally over $90\%$ of optical transmittance at wavelength range of 380-780nm and about $1\times10^{-2\~3}ohm{\cdot}cm$ of electrical resistivity. In the present study, effects of $O_2/TMT\;and\;H_2/TMT$ mole ratio on the properties of $SnO_x$ films are investigated and the other process parameters such as microwave power, magnetic current power, substrate distance and working pressure are fixed. Based on our experimental results, the $SnO_x$ film composition ratio of Sn and O directly influences on the electrical and optical properties of the films prepared. The $SnO_x$ film with low electric resistivity and high transmittance could be obtained by controlling the process parameters such as $O_2/TMT\;and\;H_2/TMT$ mole ratio, which play an important role to change the composition ratio between Sn and O. An increase of $O_2/TMT$ mole ratio brought on the increases 0 content in the $SnO_x$ film. On the other hand, an increase of $H_2/TMT$ mole ratio lead to decreases the oxygen content in the film. The optimized composition ratio of oxygen : tin Is determined as 2.4: 1 at $O_2/TMT$ of 80 and $H_2/TMT$ of 40 mole ratio, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.62-75
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• 2007

This paper describes a shaped-beam antenna for increasing the antenna gain of a radiating element. The proposed antenna structure is composed of an exciting element and a multi-layered disk array structure(MDAS). The stack micro-strip patch elements were used as the exciter for effectively radiating the electromagnetic power to the MDAS over the broadband, and finite metallic disk array elements - which give the role of a director for shaping the antenna beam with the high gain - were finitely and periodically layered onto it. The efficient power coupling between the exciter and the MDAS should be carried out in such a way that the proposed antenna has a high gain characteristic. The design parameters of the exciter and the MDAS should be optimized together to meet the required specifications to meet the required specifications. In this study, a shaped-beam antenna with high gain was optimally designed under the operating conditions with a linear polarization and the frequency band of $9.6{\sim}10.4\;GHz$. Two methods constructed using thin dielectric film and dielectric foam materials respectively were also proposed in order to implement the MBAS of the antenna. In particular, through the computer simulation process, the electrical performance variations of the antenna with the MDAS realized by the thin dielectric film materials were shown according to the number of disk array elements in the stack layer. Two kinds of antenna breadboard with the MDAS realized with the thin dielectric film and dielectric foam materials were fabricated, but experimentation was conducted only on the antenna breadboard(Type 1) with the MDAS realized with the thin dielectric film materials according to the number of disk array elements in the stack layer in order to compare it with the electrical performance variations obtained during the simulation. The measured antenna gain performance was found to be in good agreement with the simulated one, and showed the periodicity of the antenna gain variations according to the stack layer number of the disk array elements. The electrical performance of the Type 1 antenna was measured at the center frequency of 10 GHz. As the disk away elements became the ten stacks, a maximum antenna gain of 15.65 dBi was obtained, and the measured return loss was not less than 11.4 dB within the operating band. Therefore, a 5 dB gain improvement of the Type 1 antenna can be obtained by the MDAS that is excited by the stack microstrip patch elements. As the disk array elements became the twelve stacks, the antenna gain of the Type 1 was measured to be 1.35 dB more than the antenna gain of the Type 2 by the outer dielectric ring effect, and the 3 dB beam widths measured from the two antenna breadboards were about $28^{\circ}$ and $36^{\circ}$ respectively.

• Journal of Environmental Policy
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• v.7 no.4
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• pp.35-55
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• 2008

Assessing vulnerability to climate change is the first step to take when setting up appropriate adaptation strategies. Adaptive capacity to climate change is the important factor comprising vulnerability. An adaptive capacity index in agricultural water management system was developed considering agricultural water supply and demand for rice production in Jeolla-do, Korea. The agricultural water supply was assumed to be equal to the amount of water stored in the major agricultural reservoirs, while data on the agricultural water demand was obtained from the dynamic simulation results by Korea Agriculture Corporation(KAC). The spatial unit for analysis was conducted at the county(Si, Gun, Gu) level and temporal scale was based on every month from 1991-2003. Adaptive capacity for drought stress index(ACDS index) was calculated as the percentage of data points where the irrigated water supply was greater than the crop water demand. The ACDS index was compared with SWSCI(Standard Water Storage Capacity Index) and the relationship showed high degree of fit($R^2$=0.84) using the exponential function, indicating that the developed ACDS index is useful for evaluating the status of the balance between agricultural water supply and demand, especially for the small sized agricultural reservoirs. This study provided the methodological basis for developing climate change vulnerability index in agricultural water system which is projected to be more frequently exposed to drought condition in the future due to climate change. Further research should be extended to the study on the water demand of the crops other than rice and to the projection of the change in ACDS index in the future.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.5
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• pp.636-643
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• 2009

This research was to find out what impacts do selection attributes of Jeju local folklore food by Jeju tourists provide on their behaviors. Multiple regression analysis was carried out using statistics package of SPSS+/WIN 12.0 to find out impacts of selection attribute factors of Jeju local folklore food on customers' satisfaction, re-visit, and intention by word of mouth. As the results, for factors with statistically meaningful impacts at the level of meaningfulness (p<0.05); level of satisfaction showed regression coefficient of 0.476 and t value of 5.198 in essential factors; auxiliary factors showed regression coefficient of 0.232 and t value of 2.808; and sensual (five senses) factors showed regression coefficient of 0.165 and t-value of 2.013. Also, for re-visit, essential factors showed impacts with regression coefficient of 0.413 and t-value of 3.540; factors of menu composition showed regression coefficient of 0.228 and t-value of 3.118; and auxiliary factors showed regression coefficient of 0.218 and t-value of 2.643. In positive word of mouth factors, auxiliary factors showed impacts with regression coefficient of 0.273 and t-value of 2.555; sensual (five senses) factors showed regression coefficient of 0.264 and t-value of 2.238; essential factor showed regression coefficient of 0.237 and t-value of 2.230 and factors of menu composition showed regression coefficient of 0.161 and t-value of 2.167. Therefore, in customer behaviors (customer satisfaction, re-visit, and positive word of mouth) regarding Jeju local folklore food by tourists who visited Jeju, local folklore and cultures did not impact on customer behaviors; also, it can suggested this thesis is meaningful as a study proving that the best marketing is focus on essential substances of food as indicated in existing researches.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.10
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• pp.1535-1544
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• 2010

This study was conducted to evaluate the sanitation management practices in food manufacturing companies that supply food and food ingredients to school foodservice operations. Subjects consisted of 34 food manufacturing factories located in the Daegu and Gyeongbuk areas. Sanitation performance was self-evaluated using a Likert 5-point scale. The total mean score for factory sanitation performance was 4.72. Scores for perceived sanitation management performance in the factories were as follows: management of material (4.90); personal hygiene (4.78); management of work (4.71); management of workplace and vicinity (4.68); and food and raw material transportation (4.67). Participating companies that had HACCP certification programs scored high on the following sanitation inspection items: washing and sanitation guides, adequate equipment for correct hand washing, and sanitation of raw material delivery vans. The mean frequency for employee sanitation education was 2.8 times per month. Factory managers believed that their sanitation management programs kept their food safe and that the food was produced and delivered with a high degree of safety. However, they thought that food sanitation standardization was needed in order to supply high-quality and safe food items. In terms of traceability, 58.8% of the raw materials were traceable and 61.8% of the manufactured products were traceable. Sanitation management performance scores for the participating food manufacturing companies were high, although the soybean sprouts processing companies had comparatively low scores. Management reinforcement of employee sanitation education and a sense of duty and pride among factory employees will promote adequate and appropriate sanitation management performance for food safety and quality in factories that supply food and ingredients to school foodservice operations.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.415-422
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• 2009

We previously demonstrated that zinc plus arachidonic acid (ZA) treatment lowered blood glucose levels in streptozotocin-induced diabetic rats, genetically diabetic obese (ob/ob) mice, and genetically diabetic, non-obese Goto-Kakizaki rats. However, plasma insulin levels did not increase with ZA treatment, suggesting that ZA lowers blood glucose levels not by stimulating pancreatic insulin secretion. However, it is unclear whether these agents lower blood glucose levels by decreasing hepatic glucose output (HGO) or by increasing glucose utilization in peripheral tissues, or both. In order to determine ZA target organ of insulin action, we divided 18 Sprague-Dawley rats weighing ${\sim}130g$ into 3 groups (6 rats per group) and treated them for four weeks with: (1) Control diet (regular rat chow), (2) High fructose (60.0%) diet only, and (3) the same fructose diet plus zinc (10 mg/L) and arachidonic acid (50 mg/L) containing drinking water. After 4 weeks, insulin action was assessed using the hyperinsulinemic euglycemic clamp technique. Food intake and body weights were comparable in all three groups of rats throughout the study period. Plasma glucose and insulin concentrations, glucose uptake, and HGO in the basal state were all the same in these three rat groups. During the clamp study, fructose-treated and fructose+ZA treated rat groups did not exhibit any detectable change on insulin-mediated glucose uptake compared to controls. High fructose feeding impaired insulin mediated suppression of HGO, compared to controls during clamp (4.39 vs. 2.35 mg/kg/min; p<0.05). However, ZA treatment in high fructose-fed rats showed a remarkable increase in hepatic insulin sensitivity compared to high fructose-fed rats, reflected by a complete recovery in suppression of HGO during the clamp (4.39 vs. 2.18 mg/kg/min; p<0.05). This data suggests that ZA increases insulin sensitivity in liver but not glucose utilization of peripheral tissues in high fructose-fed rats.

• Journal of Korean Society of Forest Science
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• v.98 no.1
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• pp.115-124
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• 2009

New strain needs to maintain desirable characteristics for long term when it was bred, but in lapse of time it degenerates into a bad condition. Therefore the influence of temperature on the viability and survival rates of Lentinula edodes strains were examined after cryopreservation. Also, liquid nitrogen preservation for L. edodes has been proved to be one of the most reliable method. However, a mechanical damage of strain is inevitable during cryopreservation of the fungus because the fungus is very sensitive to stress of cooling rate in the freezing process. So we tried to find out state change of L. edodes with a programmable freezer. L. edodes strains were preserved at $-20^{\circ}C$, $-80^{\circ}C$ and $-196^{\circ}C$ for 50 days. At $-20^{\circ}C$, its mycelial growth became extinct. When thawed, the growth of mycelia which were preserved at $-80^{\circ}C$ was fastest. Attempts were made to investigate viability of L. edodes strains after freezing at $-80^{\circ}C$ and $-196^{\circ}C$, respectively. As the result, more than 90% showed high survival rate of strains tested at $-80^{\circ}C$ and $-196^{\circ}C$. Mycelial growth between apical and basal parts of colony after freezing preservation for 50 days was compared. At apical and basal parts, the survival rates showed 100% at $-80^{\circ}C$, but 98% and 94% at $-196^{\circ}C$, respectively. We confirmed that the ice crystal formation temperatures of L. edodes strains were $-6.0^{\circ}C$ for Sanlim 1, $-5.5^{\circ}C$ for the Sanlim 2, $-4.0^{\circ}C$ for the Sanlim 3 and $-15.5^{\circ}C$ for the Sanzo 302. These results indicated that L. edodes strains showed completely different responses to the ice crystal formation. We knew the fact that even the same species, especially L. edodes, they displayed completely different responses to the same freezing condition. Also, this has nothing to do with the connection between temperature type and freezing point. And a protocol was tried to minimize state change of L. edodes strains using programmable freezer when they are frozen, but it was not effective on them.