• Applied Chemistry for Engineering
• /
• v.30 no.1
• /
• pp.74-80
• /
• 2019

$Nafion/TiO_2$ composite membranes were prepared via an in-situ sol-gel process with different immersing periods from 1 day to 7 days for the low humidifying proton exchange membrane fuel cell. As the immersing time increased, the $TiO_2$ content within the Nafion membrane increased. The contact angle decreased with the increased $TiO_2$ content in the composite membrane due to the increased hydrophilicity. The water uptake and proton conductivity reached to the highest level for 4 day immersing period, then decreased as the immersing period increased. A 7 days of immersing time was shown to be too long because too much $TiO_2$ aggregates were formed on the membrane surface as well as interior of the membrane, interfering the proton transfer from anode to cathode. Cell performance results were in good agreement with those of the water uptake and proton conductivity; current densities under a relative humidity (RH) of 40% were 0.54, 0.6, $0.63A/cm^2$ and $0.49A/cm^2$ for the immersing time of 1, 3, 4 and 7 days, respectively at a 0.6 V. The composite membrane prepared via the in-situ sol-gel process exhibited the enhancement in the cell performance under of RH 40% by a maximum of about 66% compared to those of using the recasting composite membrane and Nafion 115.

• Transactions of the Korean hydrogen and new energy society
• /
• v.21 no.1
• /
• pp.64-71
• /
• 2010

This paper deals with an economic evaluation of domestic immersing type photoelectrochemical hydrogen production. We also make some sensitivity analysis of hydrogen production prices by changing the values of input factors such as the initial capital cost, the solar to hydrogen conversion efficiency, and the system duration time. The hydrogen production price of the immersing type photoelectrochemical system was estimated as 8,264,324 won/$kgH_2$. It is expected that the production cost by photoelectrochemical hydrogen production can be reduced to 26,961 won/$kgH_2$ if the solar to hydrogen conversion efficiency is increased to 14%, the system duration time is increased to 20,000 hours, and the initial capital cost is decreased to 10% of the current level. The photoelectrochemical hydrogen production is evaluated as uneconomical at this time, and we need to enhance the solar to hydrogen conversion efficiency and the system duration time as well as to reduce prices of the system facilities.

• Journal of the Korean Society for Heat Treatment
• /
• v.6 no.2
• /
• pp.59-69
• /
• 1993

Bending fracture strength test and impact strength test were made for VC coated die steels treated by immersing in molten borax bath and for hardened steels which were quenched and tempered, in order to clarify the effect of VC coating at $1000^{\circ}C$. The material used in this investigation was representative cold and hot work die steels STD11, STD61. The results obtained are as follows. 1) The bending fracture strength of VC coated die steel (STD11, STD61) was lessened with increasing the thickness of the VC coated layer. 2) With increasing the immersing time (imcreasing the thickness of the VC coated layer) the maximum hardness was obtained at 480 minutes holding, after that holding time hardness was decreased. 3) The impact strength of the VC coated die steel was not decreased. In the casse of STD11, it was higher than that of the quenched condition especially at low tempering temperature, and vice versa at high tempering temperature. However in the case of STD61 shows the result to the contrary.

• Journal of agriculture & life science
• /
• v.46 no.5
• /
• pp.37-45
• /
• 2012

This study was carried out to examine the optimal treatment conditions of ethanol and glycerine for processing technology development of preserved flowers in carnation (Dianthus caryophyllus) 'Desio' commonly used for flower design. For this purpose, effects of dipping duration of ethanol solution and treatment duration and concentration of glycerine on preserved flower quality were evaluated. Ethanol treatment resulted in perfect dehydration and decoloration of petals and it was proper at 24~48 hours under high brightness and low chroma. Appropriate concentration and time of glycerine treatment was 30% at 36 hours because it resulted in Munsell value of 4.0R in Hue, 6.49 in Value, and 19.8 in Chroma (4.0R 6.49/14) representing the most approximate value to that of fresh petals. Decreasing rate in weight after desiccation tended to reduce by longer time of immersing and higher concentration. Weight after 12 hours of immersing reduced up to 86~90% according to treatment time in non-treatment group of glycerin, meanwhile, it reduced up to 51~69% under higher concentration of 40%. However, weight after 48 hours of immersing reduced up to 90% regardless of desiccation time in non-treatment group of glycerine, to the contrary, decreasing rate reduced by 46~54% through glycerine treatment of 40%. Time for desiccation required 24 hours in glycerin concentration of 10~20% except 6 hours of immersing time, however, higher concentration resulted in increased time up to 48 hours.

• Plant Resources
• /
• v.4 no.3
• /
• pp.200-205
• /
• 2001

It was reported in our Previous paper that the fermented products from Gloeostereum incarnatum strongly inhibit the growth of six kinds of bacteria in human bodies. In this paper the appropriated conditions of immersing culture for the strain 8 903 of Gloeostereum incarnatum was analysed. And the output of the hypha and fermentative product was determined or compared. The prelimenaryresults showed that the appropriated conditions for the growth of Gloeostereum incarnatum are: (1)culture medium:glucose 3%; protein peoptne 0.2%; soybeancake power 1% yeast power 0.3%; KH2PO40.05%; MgSO4 0.03%; CaCO3 0.01%; vitamin Bl 0.001%; befor sterilization pH Value of six should be maintained; (2) temperature; 27f ~28f ; (3) time; about 200 hours; (4) ventilation; (30%∼50%)/min. The sigh of the end culture are: pH coming down about 4: remnant glucoses less 1%; amino nitrogens about 20%; time about eight days. In the aforementioned conditions, the output of fermentative product achieve to 2.5∼3g/L.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2001.11a
• /
• pp.74-82
• /
• 2001

It was reported in our Previous paper that the fermented products from Gloeostereum incarnatum strongly inhibit the growth of six kinds of bacteria in human bodies. In this paper the appropriated conditions of immersing culture for the strain 8 903 of Gloeostereum incarnatum was analysed. And the output of the hypha and fermentative product was determined or compared, The prelimenaryresults showed that the appropriated conditions for the growth of Gloeostereum incarnatum are: (1)culture medium:glucose 3%; protein peoptne 0.2%; soybeancake power 1%, yeast power 0.3%; KH2PO40.05%; MgSO4 0.03%; CaCO3 0.01%; vitamin Bl 0.001%; befor sterilization pH Value of six should be maintained; (2) temperature; 27$^{\circ}C$～28$^{\circ}C$; (3) time; about 200 hours; (4) ventilation; (30%～50%)/min. The sigh of the end culture we: pH coming down about 4: remnant glucoses less 1%, amino nitrogens about 20;, time about eight days. In the aforementioned conditions, the output of fermentative product achieve to 2.5 ～3g/L.

• Journal of Environmental Science International
• /
• v.19 no.1
• /
• pp.9-16
• /
• 2010

This pilot study evaluated fueling feasibility of sewage sludge, which contains a large amount of water content, by applying melting of thermoplastic polyethylene (PE). This study has identified a simultaneous achievement of drying and heating value improvement of the sewage sludge. The sewage sludge collected from a sewage sludge treatment plant during a winter period had a water content of 83.7 wt%, a combustible volatile content of 12.5 wt%, and an ash content of 3.8 wt%. The higher heating value (HHV) of the dried sewage sludge, before impregnation or coating of PE, was 4,600 kcal/kg. The collected sewage sludge was immersed into the melted PE solution, which had a HHV of 11,070 kcal/kg, and kept immersing with increasing reaction time. As the reaction (immersing or coating or impregnation) time increased, the water content of the sludge decreased. However, the HHV of the sludge increased with increasing the reaction time. The HHVs of the sewage sludge immersed or dipped into the melted PE solution for 15 min ranged from 6,780 to 8,170 kcal/kg with water content less than 7 wt%. This result indicates the melted PE solution can be utilized as an improvement technology for dryness and heating value of the sewage sludge with high water content. The sewage sludge impregnated or coated with melted PE can be utilized as potential fuel or energy resources.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.23 no.2
• /
• pp.326-334
• /
• 1999

Polyaniline(PAn)-nylon 6 composite fabrics were prepared by immersing the nylon 6 fabrics in 100% distilled aniline for specified diffusion time and drawn out. Then the excess aniline on the fabric surface was blotted and successive polymerization was initiate by immersing them into oxidant and dopant solution for in situ polymerization of polyaniline. Consequently highly conductive PAn-nylon 6 composite fabrics could be obtained and the conductivity reaches as high as 10-2 S/cm. The maximum conductivity was obtained when the fabric was immersed in 100% aniline at 4$0^{\circ}C$ for 3hours and polymerization was proceeded in 0.25M ammonium peroxydisulfate solution at 5$^{\circ}C$ for 1hour.

• The Journal of the Korea Contents Association
• /
• v.8 no.3
• /
• pp.182-189
• /
• 2008

The purpose of this study were to investigate 1) present condition of children's usage of computer game, 2) difference in extent of immersing in computer game according to grade, and 3) difference in extent of immersing in computer game according to conditions of computer game usage. A total of 239 children from 1st to 3rd grade in an elementary school in Busan were surveyed with two kinds of questionnaires about usage of and immersion in computer game. The collected data were analyzed using SPSS 12.0 program. It was revealed that the 1st graders showed higher scores on experience of computer game, frequency of computer game per week, and amount of time for each computer game than the 3rd graders. However, there were no significant differences in extent of immersing in computer game according to grade and to conditions of computer game usage. The findings of this study implies that the age of using computer game is going down rapidly. Discussions and suggestions for further study were provided.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.24 no.3
• /
• pp.17-26
• /
• 2011

Objectives : Corydalis tuber has been used for promoting blood circulation and for relieving pain in Oriental medicine. In the present study, we focused on the antimicrobial activity of Corydalis tuber and compared its antimicrobial activity with the processed Corydalis tuber. Methods : Processing of Corydalis tuber was accomplished by immersing in 5% of acetic acid for 12 h and then by roasting at $250^{\circ}C$ for indicated time periods(0-30 min). Minimum inhibitory concentration(MIC) and the zone of growth inhibition were determined against Propionibacterium acnes(P. acnes). Results : The methanolic extracts of Corydalis tuber showed potent antimicrobial effect(MIC 62.5 ${\mu}g/ml$). Its alkaloidal component, dehydrocorydaline, also exhibited antibacterial activity(MIC 25.0 ${\mu}g/ml$). After processing of Corydalis tuber, its inhibitory effect on the growth of P. acnes was significantly enhanced compared with that of unprocessed Corydalis tuber. Furthermore, elevated content of dehydrocorydaline was found in the processed than the unprocessed Corydalis tuber. However, the different roasting minutes effected on antimicrobial activity. The best roasting time of Corydalis tuber was 10 min, while roasting for the time above 15 min resulted in diminishing antimicrobial activity. Thus, it was concluded that the standardized processing condition of Corydalis tuber should be established to obtain enhanced antimicrobial(P. acnes) activity. Conclusion : For antimicrobial effect against P. acnes, the best processing condition of Corydalis tuber is immersing in 5% of acetic acid for 12 h and by roasting at $250^{\circ}C$ for 10 min.