• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.4
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• pp.427-438
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• 2023

Objectives: This study aims to create a safer working environment by examining the working environment of cleanroom cleaning workers through a survey and comparing the differences in perception between workers and managers. Methods: The survey was written based on the working environment and the safety and health management system. In order to improve the quality of the study, we visited the sites in person and conducted an in-depth interview. SPSS Statistics 26 (IBM, USA) was used to analyze the data. Results: Based on the survey, differences were found in chemical used, MSDS sharing methods, risk factors during cleaning work, work environment measurement results, special health examination items, places considered dangerous, and work. Conclusions: It is necessary that there be different work environments and risk factors for cleanroom cleaning workers at respective workplaces. As a result of the survey, there was found to be a difference in perception between workers and managers, and both workers and managers should try to reduce this difference.

• Journal of Animal Science and Technology
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• v.62 no.5
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• pp.682-691
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• 2020

Careful cleaning and disinfection of pigpens is essential to prevent disease spread and avoid the resultant economic losses. Hygiene in pigpens is generally evaluated by visual monitoring supplemented with bacteriological monitoring, which includes counting the total aerobic bacteria (TAB) and/or fecal indicator bacteria (FIB). However, these methods present drawbacks such as time and labor requirements. As adenosine triphosphate (ATP) is ubiquitous in all living organisms including microorganisms, this study aimed to directly compare the results of microbial assessment and ATP quantification, and to suggest possible detailed application methods of the ATP test for hygiene evaluation in pigpens of a farrowing unit. Before and after standard cleaning procedures, samples were collected from the floor corner, floor center, and feeding trough of four pigpens at different time points. No FIB were detected and both the TAB and ATP levels were significantly decreased in the floor center area after cleaning. FIB were continuously detected after cleaning and disinfection of the floor corners, and there was no significant ATP level reduction. The feeding trough did not show any significant difference in these values before and after cleaning, indicating insufficient cleaning of this area. The levels of TAB and ATP after cleaning were significantly correlated and the average ATP value was significantly lower in the absence of FIB than in their presence. In the absence of standard references, a more thorough hygiene management could be achieved evenly by supplementing cleaning or disinfection based on the lowest ATP results obtained at the cleanest test site, which in the present study was the floor center. Overall, these results indicate that the on-farm ATP test can be used to determine the cleanliness status, in addition to visual inspection, as an alternative to laboratory culture-based testing for the presence of microorganisms.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.5
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• pp.150-156
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• 2009

The removal of tiny particles adhered to surfaces is one of the crucial prerequisite for a further increase in IC fabrication, large area displays and for the process in nanotechnology. Various cleaning techniques (wet chemical cleaning, scrubbing, pressurized jets and ultrasonic processes) currently used to clean critical surfaces are limited to removal of micrometer-sized particles. Therefore the removal of sub-micron sized particles from silicon wafers is of great interest. For this purpose various cleaning methods are currently under investigation. In this paper, we report on experiments on the cleaning effect of 100nm sized fluorescence particles on silicon wafer using the plasma shockwave occurred by femtosecond laser. The plasma shockwave is main effect of femtosecond laser cleaning to remove particles. The removal efficiency was dependent on the gap distance between laser focus and surface but in some case surface was damaged by excessive laser intensity. These experiments demonstrate the feasibility of femtosecond laser cleaning using 100nm size fluorescence particles on wafer.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.688-694
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• 2009

A spray-type cleaning agent in utilizing dust-remover on PCB was chosen to study the cleanliness test and efficiency. In order to choose alternative environmental-friendly cleaning agents, it is important that the systematic selection procedures should be introduced and applied through the evaluation of their cleaning ability, environmental characteristics, and economical factors, and that the objective and effective evaluation methods of cleanliness should be established for the industry. A novel cleaning evaluation method with scanning electron microscopy/energy-dispersive X-ray analysis of surface observation evaluation method and an infra-red thermography camera(THERMOVISION A20 model) was studied in this work. The sound card(CT-2770 model) cut by $2{\times}2cm$ size was used as a part, and before and after the spray cleaning, the cleanliness was observed by the image analyzer of SEM and further the removal efficiency of dust was quantitatively evaluated by the component analysis of EDX. For the parts of P4TE model motherboard and IPC-A-36 PCB plate, before and after the spray cleaning, temperature differences were measured and compared at room temperature and 50 oven temperature by an infra-red thermography camera in the contaminants of dust and iron powder.

• Journal of the Korean Society of Costume
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• v.65 no.7
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• pp.47-59
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• 2015

This paper studies the conservation treatment of Lady Shim's costume, which was excavated in Jecheon Province in 2012. There were the significant problems, which were encountered in the treatment of the costume ; First the Jeogoris were transformed during the excavation, Second fibers were seriously deteriorated, Third most of the fabrics such as Chusa were readily deformed. To overcome these problems and to secure stability in the conservation treatment, we decided to alternate between two different washing methods ; dry cleaning by n-hexane and wet cleaning by water. The costume shape was recovered by steaming and by swelling with Hanji(Korean traditional paper). The combined cleaning method proved to be relatively efficient and stable. In addition, the shape of Chusa was well preserved by dry cleaning.(using n-hexane also solved the problem of bad smell after washing with organic solvents.) The effects of the conservation treatment on the excavated costumes could be seen in the change of Lab color difference. Washing made the distribution of Lab color difference narrower, which may suggest that the impurities on the fiber was removed by washing. In addition, the value of L was greater than a-value and b-value after the treatment. This result indicates that the change of value represents the change of color difference by cleaning.

• Restorative Dentistry and Endodontics
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• v.45 no.2
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• pp.19.1-19.8
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• 2020

Objective: This study aimed to evaluate the effect of ultrasonic cleaning of the intracanal post space on the bond strength of fiber posts in oval canals filled with a premixed bioceramic (Bio-C Sealer [BIOC]) root canal sealer. Materials and Methods: Fifty premolars were endodontically prepared and divided into 5 groups (n = 10), based on the type of root canal filling material used and the post space cleaning protocol. A1: gutta-percha + AH Plus (AHP) and post space preparation with ultrasonic cleaning, A2: gutta-percha + BIOC and post space preparation with ultrasonic cleaning, B1: gutta-percha + AHP and post space preparation, B2: gutta-percha + BIOC and post space preparation, C: control group. Fiber posts were cemented with a self-adhesive luting material, and 1 mm thick slices were sectioned from the middle and cervical third to evaluate the remaining filling material microscopically. The samples were subjected to a push-out test to analyze the bond strength of the fiber post, and the results were analyzed with the Shapiro-Wilk, Bonferroni, Kruskal-Wallis, and Mann-Whitney tests (p < 0.05). Failure modes were evaluated using optical microscopy. Results: The results showed that the fiber posts cemented in canals sealed with BIOC had lower bond strength than those sealed with AHP. The ultrasonic cleaning of the post space improved the bond strength of fiber posts in canals sealed with AHP, but not with BIOC. Conclusions: BIOC decreased the bond strength of fiber posts in oval canals, regardless of ultrasonic cleaning.

• Membrane and Water Treatment
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• v.8 no.2
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• pp.113-123
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• 2017

This study investigated effects of physical and chemical cleaning methods on the initial flux recovery of fouled membrane in membrane distillation process. A laboratory scale direct contact membrane distillation (DCMD) experiment was performed to treat digested livestock wastewater with 3.89 mg/L suspended solids, 874.7 mg/L COD, 543.7 mg/L nitrogen, 15.6 mg/L total phosphorus, and pH of 8.6. A hydrophobic PVDF membrane with an average pore size of $0.22{\mu}m$ and a porosity of 75 % was installed inside a direct contact type membrane distillation module. The temperature difference between feed and permeate side was maintained at $40^{\circ}C$ with the feed and permeate stream velocity of 0.18 m/s. The results showed that the permeate flux decreased from $22.1L{\cdot}m^{-2}{\cdot}hr^{-1}$ to $19.0L{\cdot}m^{-2}{\cdot}hr^{-1}$ after 75 hours of distillation. The fouled membrane was cleaned first by physical flushing and consecutively by chemicals with NaOCl and citric acid. After the physical cleaning the flux was recovered to 92 % as compared with the initial clean water flux of the virgin membrane. Then 94 % of the flux was recovered after cleaning by 2,000 ppm NaOCl for 90 minutes and finally 97 % of flux recovered after 3 % citric acid for 90 minutes. SEM-EDS and FT-IR analysis results presented that the foulants on the membrane surface were removed effectively after each cleaning step. The contact angle measurement showed that the hydrophobicity of the membrane surface was also restored gradually after each cleaning step to reach nearly the same hydrophobicity level as the virgin membrane.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.4
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• pp.419-426
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• 2023

Objectives: This study aims to develop an Occupational Safety and Health (OSH) guide for the safe cleaning of contaminated machinery, equipment, and parts used in the electronics manufacturing process. Methods: A literature review, field investigations, and discussions were conducted. An initial draft of an OSH guide was developed and reviewed by experts with significant experience in maintenance work in the electronics manufacturing process in order to refine the guide. Results: Workers involved in cleaning processes with chemicals, solvents, and abrasive blasting can face exposure to a wide range of chemicals, abrasives, and noise. Identifying potential risks associated with each cleaning technique was an essential first step toward enhancing safety measures. The OSH guide comprises approximately eleven to twelve sections spanning 20-25 pages. It includes engineering and administrative protocols systematically organized to address the necessary actions before, during, and after cleaning tasks, depending on the technique. It is recommended that airline respirator masks be used in conjunction with an air purification system to ensure adherence to air quality standard "D" for atmosphere level. The use of an oil-free air compressor is advised, preferably a stationary model that does not rely on fuel sources like diesel. Conclusions: This OSH guide is designed to protect workers involved in maintenance activity in the electronics industry and aligns with global standards, such as those from the International Organization for Standardization (ISO) and Semiconductor Equipment and Material International, ensuring a higher level of safety and compliance.

• Journal of radiological science and technology
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• v.41 no.3
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• pp.241-247
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• 2018

The purpose of this study was to compare the ultrasound gel container washing methods for the sterilization of contaminants and to find the useful methods for the prevention of infection caused by the ultrasonic gel containers. In this experiment, a 250 mL ultrasonic gel container was used, and the ultrasonic gel used was a non-sterile gel (ECO GEL 99, SeungWon Medical, Korea). In order to evaluate the degree of contamination, new 250 mL 15 containers were divided into 5 groups to perform five types of washing by no treatment, washing with water, washing with soap, washing with bottle cleaner and high disinfection level washing. After the washing process, filled the gel container with gel and after 2 weeks, the number of colonies in the gel container was sampled repeatedly twice in the same ultrasonic laboratory and compared before and after washing. As a result of among the five cleaning methods used in this study, 87.2% and 88.9% of the soapy water washing (p = 0.028) and high level washing (p = 0.027) showed significant bacterial reduction rates, respectively. Our findings conclusively an ultrasonic gel container cleaning method for removing contaminants has been found to be an effective sterilization method at a low cost with a soapy water cleaning method. Therefore, it is expected that it will be helpful to prevent the infection caused by the ultrasonic gel container by suggesting the sterilization cleaning method that is practically useful in this study.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.9_10
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• pp.1134-1143
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• 2003

The purpose of this study is to investigate surface color change and effects of mordants on the K/S values of silk and wool fabrics dyed with Lac extract, according to the mordanting methods and conditions such as temperature, concentration and time of the mordanting bath. The results were as follow; 1 K/S values of the silk and wool fabrics according to the temperature of the mordanting bath were shown a slight decline beyond 40$^{\circ}C$. 2. Surface color of the silk changed from red to reddish purple and that of the wool showed red tone when mordanted with Aluminum postassium sulfate, Copper acetate and Copper (II) sulfate regardless of the mordanting conditions. 3. The light and dry cleaning fastness of silk and wool fabrics dyed with Lac extract according to the mordanting methods were very good.