• Particle and aerosol research
• /
• v.18 no.4
• /
• pp.129-136
• /
• 2022

The line width of circuits in semiconductor devices continues to decrease down to a few nanometers. Since nanoparticles attached to the patterned wafer surface may cause malfunction of the devices, it is crucial to remove the contaminant nanoparticles. Physical cleaning that utilizes momentum of liquid for detaching solid nanoparticles has recently been tested in place of the conventional chemical method. Dropwise impaction has been employed to increase the removal efficiency with expectation of more efficient momentum exchange. To date, most of relevant studies have been focused on drop spreading behavior on a horizontal surface in terms of maximum spreading diameters and average spreading velocity of drop. More important is the local liquid velocity at the position of nanoparticle, very near the surface, rather than the vertical average value. In addition, there are very scarce existing studies dealing with microdroplet impaction that may be desirable for minimizing pattern demage of the wafer. In this study, we investigated the local velocity distribution in spreading liquid film under various impaction conditions through the CFD simulation. Combining the numerical results with the particle removal model, we estimated an effective cleaning diameter (ECD), which is a measure of the particle removal capacity of a single drop, and presented the predicted ECD data as a function of droplet's velocity and diameter particularly when the droplets are microns in diameter.

• The KIPS Transactions:PartD
• /
• v.13D no.3 s.106
• /
• pp.377-382
• /
• 2006

Advantageous features of flash memory are stimulating its exploitation in mobile and ubiquitous related devices. The hardware characteristics of flash memory however place restrictions upon this current trend. In this paper, a cleaning policy for flash memory is proposed in order to decrease the necessary penally for recycling of memory minimizing the degradation of performance at the same time. The proposed cleaning algorithm is based on partitioning of candidate memory regions, to be reclaimed as free, into a number of groups. In addition, in order to improve the balanced utilization of the entire flash memory space in terms of 'wearing-out', a free segment selection algorithm is discussed. The impact of the proposed algorithms is evaluated through a number of experiments. Moreover, the composition of the optimal configuration featuring the proposed methods is tested through experiments.

• Journal of Preventive Medicine and Public Health
• /
• v.31 no.4 s.63
• /
• pp.628-643
• /
• 1998

To investigate the exposure levels of organic solvents and subjective symptoms of dry-cleaning workers, 77 male and 52 female dry-cleaning workers who had been worked in a small city of Chungnam province, and a large city, Taejon were selected for the study group. Air concentrations of organic solvents in the working environment were analyzed, and subjective symptoms of dry-cleaning workers were surveyed, from July to August 1996. The results obtained were as follows : 1. The concentrations of organic solvents in the working environment were within permissible TLV-TWA limits. 2. For the 13 symptom clusters, the most frequently complained symptom clusters were fatigue as 71.3%, and followed by depression and urinary disturbances as 53.5% and 51.9%. Other symptom clusters complained were below 50%. 3. Positive response rates of subjective symptoms were significantly higher in worker groups such as lived in a large city, female, higher education level, more frequently alcohol drinking, higher concentration of organic solvent in working environment, work in alone. 4. Workers who had used solvent B showed 2.3 point higher scores of subjective symptoms than those of solvent A. Of the subjective symptoms scores, amnesia and nervousness were higher in solvent B user group than solvent B user group. 5. As a result of factor analysis, 3 factors such as depression, urinary disturbance and neurologic disturbance were selected. 6. As a result of the logistic regression analysis, sex, the number of fellow workers, working time, region, job tenure, smoking, alcohol drinking, ventilating system, concentration of organic solvent in working environment and place of residence were selected for the related variables. For the conclusion, even though the concentrations of organic solvents in the working environments of dry-cleaning workers were within permissible limit of TLV-TWA, many dry-cleaning workers complained symptoms, such as fatigue, depression, urinary disturbances and so on. And the factors affecting to the symptoms of dry-cleaning workers were the number of fellow workers, work hours, region, job tenure, smoking and alcohol drinking.

• Journal of Korean Institute of Industrial Engineers
• /
• v.37 no.4
• /
• pp.415-420
• /
• 2011

Snow removal system is named for machinery which manages roads for passing of pedestrians and automobiles when snow is piled up on the road. This paper studies configuration design of snow removal system that has several functions-melting snow in the street without moving it to other place, transferring snow to the melter and cleaning road by spraying water for cleaning road. These sorts of functions are analyzed by function decomposition method of Kirshman and Fadel and, based upon which, machine parts are selected. Layout design would follow functional design to testify if the selected component satisfies space which is allowed by constraints.

• Korean Journal of Materials Research
• /
• v.18 no.6
• /
• pp.307-312
• /
• 2008

In this study, a new cleaning process with a low cost of ownership (CoO) was developed with ozonated DI water ($DIO_3$). An ozone concentration of 40 ppm at room temperature was used to remove organic wax film and particles. Wax residues thicker than $200\;{\AA}$ remained after only a commercial dewaxer treatment. A $DIO_3$ treatment in place of a dewaxer showed a low removal rate on a thick wax layer of $8000\;{\AA}$ due to the diffusion-limited reaction of ozone. A dewaxer was combined with a $DIO_3$ rinse to reduce the wax removal time and remove wax residue completely. Replacing DI rinse with the $DIO_3$ rinse resulted in a surface with a contact angle of less than $5^{\circ}$, which indicates no further cleaning steps would be required. The particle removal efficiency (PRE) was further improved by combining a SC-1 cleaning step with the $DIO_3$ rinsing process. A reduction in the process time was obtained by introducing $DIO_3$ cleaning with a dewaxing process.

• Conservation Science in Museum
• /
• v.3
• /
• pp.29-36
• /
• 2001

The hat excavated from the tomb of Hojeo-myon Wonsung-gun in Kangwon province was dry-cleaned and restored. The hat was made of wool felt and decorated with several strands of silk cord. It was very dirty and moth-eaten. After getting rid of the particle soils on a surface with painting brush, the hat was dry-cleaned using perchloroethylene applying the minimum force, and blotting paper was used for drying. During cleaning, it was supported by the stainless steel net. The weight loss was 7.94% after cleaning. The soils sticked on the hat was removed clearly. The texture of the hat became softer after cleaning. Color difference(∆E) was 2.57, which is a noticeable change. The color became clear and changed to the red and yellow range. After dry-cleaning, the hat was repaired. Dislocated silk cords were fixed to the right place by stitching with silk yarn. To keep the shape of the hat, it should be supported by a hat-shaped stiff net during exibition and storing.

• Corrosion Science and Technology
• /
• v.9 no.6
• /
• pp.276-280
• /
• 2010

Copper(Cu) as an interconnecting metal layer can replace aluminum (Al) in IC fabrication since Cu has low electrical resistivity, showing high immunity to electromigration compared to Al. However, it is very difficult for copper to be patterned by the dry etching processes. The chemical mechanical polishing (CMP) process has been introduced and widely used as the mainstream patterning technique for Cu in the fabrication of deep submicron integrated circuits in light of its capability to reduce surface roughness. But this process leaves a large amount of residues on the wafer surface, which must be removed by the post-CMP cleaning processes. Copper corrosion is one of the critical issues for the copper metallization process. Thus, in order to understand the copper corrosion problems in post-CMP cleaning solutions and study the effects of DC biases and post-CMP cleaning solution concentrations on the Cu film, a constant voltage was supplied at various concentrations, and then the output currents were measured and recorded with time. Most of the cases, the current was steadily decreased (i.e. resistance was increased by the oxidation). In the lowest concentration case only, the current was steadily increased with the scarce fluctuations. The higher the constant supplied DC voltage values, the higher the initial output current and the saturated current values. However the time to be taken for it to be saturated was almost the same for all the DC supplied voltage values. It was indicated that the oxide formation was not dependent on the supplied voltage values and 1 V was more than enough to form the oxide. With applied voltages lower than 3 V combined with any concentration, the perforation through the oxide film rarely took place due to the insufficient driving force (voltage) and the copper oxidation ceased. However, with the voltage higher than 3 V, the copper ions were started to diffuse out through the oxide film and thus made pores to be formed on the oxide surface, causing the current to increase and a part of the exposed copper film inside the pores gets back to be oxidized and the rest of it was remained without any further oxidation, causing the current back to decrease a little bit. With increasing the applied DC bias value, the shorter time to be taken for copper ions to be diffused out through the copper oxide film. From the discussions above, it could be concluded that the oxide film was formed and grown by the copper ion diffusion first and then the reaction with any oxidant in the post-CMP cleaning solution.

• Korean Journal of Veterinary Service
• /
• v.41 no.2
• /
• pp.125-131
• /
• 2018

This study investigated the effects of the alkaline detergent and acid rinse used for cleaning milking machines on the rubber composition of the newly-developed teat cup liners. The samples prepared for use in the clean-in-place process were analyzed by ultraviolet spectrophotometer, ion chromatography and liquid chromatography. In the absorption spectrum of the first sample solution, the form of absorbance or absorption peak was largely different, compared to the absorption spectrum of alkaline detergent alone, but in the absorption spectra of the second and third sample solutions, the absorbance decreased, which was similar to the absorption spectrum in the pure acid detergent. In the ion chromatogram, two main peaks only, which might be shown by the pure alkaline detergent alone, were measured. In the liquid chromatograms, however, new peaks were observed in addition to the two main peaks caused by the pure alkaline detergent alone, which suggested that various molecular materials were created or eluted from the liner by the reaction with the alkaline detergent, but when washed with the acid detergent, any ion species were not produced. Therefore, we propose that an acid rinse should be applied, after cleaning the milking machine with the alkaline detergent.

• Journal of Animal Science and Technology
• /
• v.64 no.2
• /
• pp.343-352
• /
• 2022

Pig slaughterhouses harbor high humidity because of the necessary cleaning that takes place simultaneously with slaughter, which facilitates the existence of mold. Due to the enclosed space, there are several limitations to the control of mold growth with respect to cleaning, ventilation, and drying. In this study, the prevalence of fungi was investigated in four pig slaughterhouses in Korea. Four fungi (Aspergillus niger, Penicillium commune, Penicillium oxalicum, and Cladosporium cladosporioides) were detected with the highest frequency. These four strains were subjected to various treatments to reduce their growth. The fungi were inoculated onto stainless steel (SS) chips and treated with ultraviolet (UV)-C irradiation and hot water. Individual treatments with UV-C (15, 30, 90, 150, 300, and 600 mJ/cm²), and hot water (60, 65, 70, and 83℃) were performed to sanitize the SS chips. Simultaneous cleaning with 60℃ hot water and more than 150 mJ/cm² of UV-C reduced the fungal incidence by > 6.5 Log from 6.6-7.0 Log CFU/cm² (initial count). Our results demonstrate that a combined treatment of UV-C and hot water is the most economical and convenient way to prevent microbiological contamination of small tools (such as knives and sharpeners) and steel surfaces in slaughterhouses.

• English & American cultural studies
• /
• v.14 no.1
• /
• pp.27-51
• /
• 2014

Doris Lessing describes a band of revolutionaries who become involved in terrorist activities far beyond their level of competence in The Good Terrorist. Alice Mellings who is from a middle-class family has organized a squat house in London and seems capable of controlling everyone around her and anything about the house. She is seemingly like a housekeeper or a breadwinner. She also likes to be on the battlefront, for instance, demonstrating, picketing and spray-painting slogans. Such is able to easily exploit the others and she increasingly becomes the leader in the house. Recently some critics have focused on the political and social roles of the protagonist who represents a voice of terrorists in the 1980s England. Based on this, The Good Terrorist is read with the concept of the subject of feminism that Gillian Rose adopts in order to show that this subject tries to avoid the exclusion of the master subject. This subject imagines spaces which are not structured through masculinist claims to exhaustiveness. Alice as the subject of feminism shows different roles; she extorts or steals money for the maintenance of the house from her affluent parents; she spends all her time cleaning, fixing, decorating the deserted house; and she looks after the official affairs related to the house with her skills and experiences. She is systematically in charge of the house and sits at the head of the table in the kitchen. But when their activities turn into disaster and their plans fail, Alice willingly decides to close down the house after ousting the members. Here in her extorted gaze it is revealed that she takes control over the working class members of the house who are unable to lead a revolution because of their own problems and thereby the working class are dominated by the middle class. That is, the place is paradoxically recreated based on class differences, which the revolutionaries try to break. By representing the deconstruction and recreation of the place through squat houses, Lessing reveals her implicit feminism in which a new place should be produced crossing the principle of the dichotomy of gender and class.