• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.47 no.1
• /
• pp.59-65
• /
• 2015

In this study, we evaluated optimum condition of enzyme with pH and temperature for preparation of microfibillated cellulose(MFC). Well-known endo-glucanase, three enzymes were used and CMC was used for substrate. Enzyme activity was evaluated using DNS method and absorbance with UV/VIS spectrophotometer. The enzyme shown the greatest activity was reacted with pulps at optimum condition for 1 hour and treated pulps beated until 100 mL CSF. Enzyme B and Enzyme L was the higher enzyme activity below 0.1% concentration and Enzyme N was the lowest enzyme activity. At various pH and temperature conditions, enzyme activity of Enzyme B was higher than the others at the same concentration. Especially enzyme activity at $50^{\circ}C$ of Enzyme B was almost not changed over pH 6.0. Optimum condition of three enzyme was pH 6 or pH 7 and $50^{\circ}C$ or $60^{\circ}C$. Also beating efficiency of enzyme treated pulps with Enzyme B is 55.6%.

• Proceedings of the Korean Environmental Health Society Conference
• /
• 2003.06a
• /
• pp.174-176
• /
• 2003

A survey was conducted to investigate the sanitary condition of school kitchens in one region of Korea. A self-administered questionnaire recommended by the Korea Ministry of Education & Human Resources Development (MOEHRD) was offered to a random sample of dieticians of twenty-five elementary schools for food, sanitation and safety inspection of their kitchens. Air temperature, relative humidity, and airborne microbes in the kitchens were monitored during food preparation, processing and service. The inspection results showed their sanitary condition met the level B of the recommendation of the Korea MOEHRD. The range of air temperature of the kitchens was 21.4∼22.4$^{\circ}C$, and the range of relative humidity was 62.4∼69.6%. The microbiological evaluation of kitchen samples indicated aerobic plate count levels from 22.5 to 26.5 CFU/15 min. These results indicate that the levels of sanitary condition of kitchens in the schools were not satisfactory for safe foodservice although the inspection showed good results. This study suggests that the school kitchens should be monitored and strict inspection is necessary.

• Journal of KSNVE
• /
• v.22 no.4
• /
• pp.28-32
• /
• 2012

Condition-based maintenance on wind turbines not only involves maintenance, but also encompasses servicing, inspection, measurement and evaluation of the condition of the unit. The current condition can be evaluated on the basis of machine-specific overall vibration values. Until now, overall vibration values had not been defined for wind turbines. In fact, ISO 10816-3 explicitly excludes wind power plants. The new VDI 3834 closes this gap shown in Sheet 1: Vibration values for wind turbines up to 3 MW. In addition to the new VDI 3834 is the ISO 10816-21 in preparation. The author of the article Dr. Edwin Becker is the nominated expert for Germany.

• Proceedings of the KSR Conference
• /
• 2000.05a
• /
• pp.164-171
• /
• 2000

To determine operational requirement, the environmental condition for an equipment must be investigated, and to certify equipment's normalized operation, appropriate test must be carried out under the considered environmental condition. The actual environmental conditions to which equipment is likely to be exposed are normally complex and will comprise a number of environmental factors and corresponding parameters, When defining the environmental conditions for a certain application it is, therefore, necessary to list the factors involved and select the appropriate severity. For the preparation to determine operational requirement, environmental condition of equipment is investigated. The environmental condition is structured in two separate such as requirements, guidance and test specifications. For the first step, environmental requirements are considered

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.445-448
• /
• 2004

Recently, bridge deck overlay with latex modified concrete is widely applied in domestic. the capacity of bridge deck overlay depends on bond state on the surface. factors that have an effect on bond state are clean condition on the surface, absence of surface microcracking, absence of laitance, overlay curing. In this study, it is researched that characteristic of bond strength according to moisture condition on the surface and the removal method of concrete. As a result, it shows high bond strength in dry condition when w/c is $31\%$ and in moisture condition when w/c is $38\%$ respectively. characteristic of bond strength according to the removal method of concrete shows high bond strength when using water-jets rather than jackhammers.

• Journal of the Korean Society of Safety
• /
• v.29 no.4
• /
• pp.61-72
• /
• 2014

The aim of this study is to define the condition of optimal pre-treatment for preferable activated carbon fibers (ACFs), which are based on rayon fibers. This paper shows the ideal path of ACFs preparation process; implies that rayon fibers are pre-treated by various solvents with different times before the heating process. The pre-treated rayon fibers finally turned into desirable rayon fiber-based ACFs through optimal pre-treatment condition by heating processes. The thermal analysis method of pre-treated rayon fibers by thermo-gravimetry analyser (TGA) is an idealized tool, which analyzes the best thermal condition of pre-treatment process. Surface morphologies of resulting rayon fibers based ACFs were examined by scanning electron microscope(SEM). The results of TGA and SEM analyses show that the optimal pre-treatment condition for preparing ACFs was clearly defined, in terms of thermal stability and surface morphology.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.28 no.4
• /
• pp.392-396
• /
• 1995

Chitosan was prepared from red snow crab (Chinonecetes japonicus) under various conditions of deacetylation (NaOH concentration, heating temperature, heating time and intermittent and repetition treatment). By measuring the degree of deacetylation and the molecular weight (Mw), effect of preparation condition was studied. As the concentration of NaOH increased in deacetylation process, for chitosan treated over $40\%$ NaOH, the rate of increase of the deacetylation of chitosan decreased, but the difference of Mw decrease was nearly constant. When treatment temperature increased from $130^{\circ}C$ to $150^{\circ}C$, the deacetylation degree increased only $3^{\circ}C\;from\;84\%\;to\;87\%,$ but Mw decreased from 267,000 to 85,800. The difference of Mw decrease of chitosan treated $130-150^{\circ}C$ was larger than that with $90-130^{\circ}C$. The deacetylation degree and Mw of the chitosan prepared by continuous treatment for 3 hrs was$84\%$ and 267,000. On the other hand those of chitosan with intermittent and repetition treatment for 3hrs was $93\%$ and 28,000. In order to increase the degree of deacetylation and inhibit depolymerizing, the intermittent and repetition treatment was found to be more effective than the continuous treatment.

• Korean Journal of Social Welfare
• /
• v.60 no.3
• /
• pp.275-297
• /
• 2008

The purpose of this study is to analyse economic preparations for aging of the middle and old-aged and their determinants empirically, and then to discuss the findings and implications for the results of analysis. Data from The Social Statistics Survey conducted by Korea National Statistical Office are used in this study. From this dataset, 18,354 Middle and Old Citizens aged between 45 and 59 were selected for this study. The Conceptual framework for this study was based on Andersen's behavioral model and logistic model was used to investigate factors that affect economic preparation for aging. The results of this study can be summarized as follows. First, Proportion of middle and old citizen with no economic preparation for aging was high, and old-aged had lower level of economic preparation for aging than relative less aged. Second, male, education level, marital status, economic activities, recognition of present income, housing ownership, residental location, and total life condition improvement is positively and statistically significantly associated with economic preparations for aging. Third, while male, age, and economic activities is negatively and statistically significantly associated with private economic preparations for aging, education level, recognition of present income, and total life condition improvement is positively and statistically significantly associated with private economic preparations for aging. Fourth, while male, education level, marital status, economic activities, recognition of present income, housing ownership, residental location, and total life condition improvement, expectation of future income is positively and statistically significantly associated with secondary economic preparations for aging, age is negatively and statistically significantly associated with secondary economic preparations for aging.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.8
• /
• pp.2560-2566
• /
• 2012

The present study investigates how the thermal stability of retinol (vitamin A) encapsulated in polyester nanoparticles is influenced by the types of polyester used for the nanoparticles. A variety of polyester-retinol nanoparticles were prepared with various polyesters like: poly(ethylene adipate), PEA; poly(butylene adipate), PBA; poly(hexamethylene adipate), PHMA; and three polycaprolactones, PCL, of different molecular weights ($M_n$ ~10, 40, and 80K). The chemical stability of retinol in these nanoparticles, monitored in an aqueous solution at $25^{\circ}C$ and $40^{\circ}C$ for 4 weeks, was high in the following order of the nanoparticles prepared with PHMA > PCL 40K > PCL 10K > PCL 80K > PBA~PEA at $25^{\circ}C$ and PCL 10K > PCL 40K > PHMA > PCL 80K > PEA > PBA at $40^{\circ}C$. More importantly, this study has also found that the thermal stability of the retinol in the nanoparticles was closely connected with the melting temperatures of polyesters and polyester nanoparticles. The results were further discussed with possible factors - such as sample preparation condition (or history) and miscibility between the polyesters and retinol - affecting $T_m$ of the polyesters and the nanoparticles.

• Journal of Powder Materials
• /
• v.11 no.4
• /
• pp.294-300
• /
• 2004

This study for preparation of aluminum nitride (AlN) with high purity was carried out by self-propagating high-temperature synthesis method in two different systems, $Al-N_{2}$ and $Al-N_{2}$-AlN, with the change of nitrogen gas pressure and dilution factor. On the occasion of $Al-N_{2}$ system, unreacted aluminum was detected in the product in spite of high nitrogen pressure, 10 MPa, This may be caused by obstructing nitrogen gas flow to inner part of molten and agglomerate of aluminum, formed in pre-heating zone. In $Al-N_{2}$-AlN system, AlN with a purity of 95% or ever can be prepared in the condition of $f_{Dil}\geq0.5$, $P_{N_{2}}\geq$ 1 MPa, and the purity can be elevated to 98% over in the condition of $f_{Dil}$ = 0.7 and $P_{N_{2}}$ = 10 MPa.