• FOCUS: LIFE SCIENCE
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• no.1
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• pp.1.1-1.4
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• 2024

This article provides comprehensive guidance on the maintenance, cleaning, regeneration, and storage of silica-based HPLC (High-Performance Liquid Chromatography) columns. The general considerations emphasize the importance of using in-line filters and guard cartridges to protect columns from blockage and irreversible sample adsorption. While these measures help, contamination by strongly adsorbed sample components can still occur over time, leading to an increase in back pressure, loss of efficiency, and other issues. To maximize column lifetime, especially with UHPLC (Ultra-High Performance Liquid Chromatography) columns, it is advisable to use ultra-pure solvents, freshly prepared aqueous mobile phases, and to filter all samples, standards, and mobile phases. Additionally, an in-line filter system and sample clean-up on dirty samples are recommended. However, in cases of irreversible compound adsorption or column voiding, regeneration may not be possible. The document also provides specific recommendations for column cleaning procedures, including the flushing procedures for various types of columns such as reversed phase, unbonded silica, bonded normal phase, anion exchange, cation exchange, and size exclusion columns for proteins. The flushing procedures involve using specific solvents in a series to clean and regenerate the columns. It is emphasized that the flow rate during flushing should not exceed the specified limit for the particular column, and the last solvent used should be compatible with the mobile phase. Furthermore, the article outlines the storage conditions for silica based HPLC columns, highlighting the impact of storage conditions on the column's lifetime. It is recommended to flush all buffers, salts, and ion-pairing reagents from the column before storage. The storage solvent should ideally match the one used in the initial column test chromatogram provided by the manufacturer, and column end plugs should be fitted to prevent solvent evaporation and drying out of the packing bed.

• Journal of Nutrition and Health
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• v.30 no.6
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• pp.690-703
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• 1997

The purpose of this study were to analyze work function and labor productivity in school foodservice systems through work sampling methodology. Conventional foodservice were classified into 5 group depending on the number of meals served. Commissary school foodservices were also classified into 5 group by cluster analysis using the number of meals served, the number of satellite schools, and the duration of time for delivery of food. Work measurement through work sampling methodology was conducted in at 5 conventional and 21 commissary food -services during 3 consecutive days from September to October in 1995. Results from work measurement through work sampling methodology were as followed : The most prevalent work functions was cleaning (26.5%) and then processing (25.1%) in conventional while it was processing (30.9%) and then cleaning(25.2%) in commissary school foodservice. Delay was 22.9% and 19.7% respectively. Mean labor minutes per meal of conventional and commissary foodservics were 4.57 and 4.09 minutes, respectively : no significant difference in labor minutes per meal existed between the two systems. but mean labor minutes per meal of commissary foodsevices(1.79min) was significantly lower than that of conventional foodservice(2.33min) during work time before service (p<0.05). Productivity was significantly lower in foodservices which served less than 400 servings ; n significant differences existed among 401-70, 701-1,100 and 1,101-1,500 meals. The highest productivity was in conventional school foodservices which served 1,501-1,900meals. Labor minutes per meal of commissary school foodservice which served less than 400meals per day was significantly lower than those of foodservice which served 401-1,900meals (p<0.05). Labor minutes per meal, preparation and cleaning were positively correlation in two school foodservice systems.

• Journal of Radiation Industry
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• v.9 no.2
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• pp.91-102
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• 2015

The iridium disc, generally used in industrial radiography, is examined to find the fracture morphology and fine particles remaining on the shear blank surface. Randomly selected 1,200 discs were observed under a scanning electron microscope tilted more than $45^{\circ}$. Fracture surfaces are classified into three groups: (1) surface fall-out, (2) fracture on the edge and (3) multi-step brittle fracture, which shows the mutual relationship between the fracture morphology and remaining particles. Fracture particles were removed by cleaning the discs in a ultrasonic bath with acetone and collected at the bottom. Removed number of the particles were counted for each different group of fracture surfaces. Followings are conclusions: (1) About 80.5% of discs (966/1,200), have sound plastic shear surfaces with particles remained. (2) About 2% discs accompany surface fall-out's having large particles tens of ${\mu}m$, which is stable not to be pulled out even after the considerably long time of ultrasonic cleaning. (3) About 5% discs contain the fractures on the edge and the particles are removed thoroughly within 30 minutes. (4) 234 discs out of 1,200 discs have multi-step fracture surfaces whose particles never removed in a short period of time but come out very slowly. Such a disc having multiple-step fracture is attributed to the promate cause to the 'leaker'. It is noted here that the discs having mutiple-step fractures should be treated separately with special care, and it is need to study how to treat them.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.1
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• pp.78-82
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• 2005

Display manufacturing process has adopted RCA cleaning, applying to larger area and coping with environmental issue for last ten years. However, the approaching concept of ozonized, hydrogenised, or electrolyzed water cleaning technologies is within RCA clean paradigm. In this work, only electrolyzed anode water was applied to clean particles and organics as well as metals based on Pourbaix concept, and as a test vehicle, MgO particles were introduced to prove the new concept. The electrolyzed anode water is very oxidative with high oxidation reduction potential (ORP) and low in pH of more than 900 mV and 3.1, respectively. MgO particles were immersed in the anode water and its weight losses due to dissolution were measured with time. Weight losses were in the ranges of 100 to 500 micrograms in 250 ml anode water depending on their ORP and pH. Therefore it was concluded that the cleaning radicals in the anode water was at least in the range of 1 to $5{\times}10^{20}$ ea per 250 ml anode water equivalent to $1{\times}10^{18} ea/cm^2$. Hence it can be assumed that the anode water applied to display cleaning from now on $1{\times}10^{10}$ to $1{\times}10^{15} ea/cm^2$ ranges of contaminants are being treated. In addition, it was observed that anode water did not develop micro-roughness on hydrophobic surface while it did on the native silicon oxide.

• Korean Journal of Materials Research
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• v.6 no.8
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• pp.817-824
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• 1996

Removal of Cu impurities on Si substrates using remote H-plasma was investigated. Si substrates were intentionally contaminated by 1ppm ${CuCI}_{2}$, standard chemical solution. To determine the optimal process condition, remote H-plasma cleaning was conducted varying the parameters of rf power, cleaning time and remoteness(the distance between the center of plasma and the surface of Si substrate). After remote H-plasma cleaning was conducted, Si surfaces were analysed by TXRF(total x-ray reflection fluorescence) and AFM(atomic force microscope). The concentration of Cu impurity was reduced by more than a factor of 10 and its RMS roughness was improved by more than 30% after remote H-plasma cleaning. TXRF analysis results show that remote H-plasma cleaning is effective in eliminating Cu impurity on Si surface when it is performed under the optimal process condition. AFM analysis results also verifies that remote H-plasma cleaning makes no damage to the Si surface. The deposition mechanism of Cu impurity may be explained by the redox potential(oxidation-reduction reaction potential) theory. Based on the XPS analysis results we could draw a conclusion that Cu impurities on the Si substrate are removed together with the oxide by a "lift-off" mechanism when the chemical oxide( which forms when Cu ions are adsorbed on the Si surface) is etched off by reactive hydrogen atoms.gen atoms.

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.05a
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• pp.30.1-30.1
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• 2008

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1362-1364
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• 1995

In this paper, the automatic device for measuring the salt contamination on insulators was developed. The device consists of electronic insulators, measuring system, monitoring system, and printer. It was shown that the level of salt contamination measured by the developed device is similar to that measured by the brush cleaning method. Therefore, the developed automatic measuring device can be used in field, in order to predict the cleaning time of insulators and prevent the failure due to the salt contamination.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2001.10a
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• pp.411-415
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• 2001

Advances in computer and sensor technology have made it possible to obtain superlarge manufacturing process data in real time, letting us to extract meaningful information from these superlarge data sets. We propose a systematic data analysis procedure which field engineers can apply easily to manufacture quality products. The procedure consists of data cleaning and data analysis stages. Data cleaning stage is to construct a database suitable for statistical analysis from the original superlarge manufacturing process data. In the data analysis stage, we suggest a graphical easy-to-implement approach to extract practical information from the cleaned database. This study will help manufacturing companies to achieve six sigma quality.

• KCID journal
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• v.18 no.2
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• pp.25-32
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• 2011

The 21 livestock farms considering future installation of biogas systems were studied. These farms were examined how to raise the livestock, to treat manure, to operate facility with respect to manure characteristics. The 15 farms out of 21 farms have applied to the marine dumping and consignment treatment for treating manure and even farms which have equipped liquid fertilizing system have less capacity facility than legal standards. Characteristics of manure were affected by the scale of swine barn, clean water usage, frequency of cleaning, cleaning method, feces-urine separating method, etc. Retention time in storage (over 20 days) has resulted in lower concentration of organic matter which could reduce biogas production. This indicates that systematic barn management system is required. Inhibition tests showed that disinfectant and citric acid did not affected digestion rates at 10 times higher concentration than recommendation. However hypochlorous acid is likely to affect the anaerobic microbial activity.

• The Research Journal of the Costume Culture
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• v.12 no.3
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• pp.407-414
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• 2004

A natural dye aqueous walnut shell extract was obtained by extraction of walnut shell using water at various conditions in this study. Silk fabrics were dyed at various dyeing and mordanting conditions using walnut shell extract and various mordants (Al, Cu, Fe ions). Studies have been made on the effects of dyeing and mordanting conditions on the dyeing properties and fastness (light, water and dry cleaning fastness) of dyed silk Fabric. The results obtained in this study were as follows;. The dye content in the walnut shell extract increased with increasing extraction temperature to 90℃ and extraction time to 120min, and thereafter the dye content decreased a little. The dry cleaning and water fastness of non-mordanted silk fabrics were better than those of mordanted silk fabrics.