• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1810-1814
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• 2008

A small L-type megasonic module for nano-pattern cleaning was designed and manufactured. The impedance graph of the quartz waveguide with a piezoelectric actuator was predicted using finite element method (FEM). The peak value of the piezoelectric actuator alone was 3.373 MHz, which was the same as the experimentally measured value of 3.373 MHz (0.0% error). In addition, the maximum impedance value of the quartz waveguide with the actuator was 3.373 MHz, which agreed well with the measured value of 3.362 MHz (0.3% error). The acoustic pressures of a conventional megasonic system (3 MHz) and the developed system under similar conditions were measured and compared. The results showed that the maximum values and standard deviations of the developed system decreased by 29% and 18%, respectively, compared with the conventional type. This suggests that the small L-type would have higher particle removal efficiency with lower possibilities of pattern damages.

• The Journal of Advanced Prosthodontics
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• v.6 no.3
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• pp.233-240
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• 2014

PURPOSE. To evaluate the effects of different abutment geometries in combination with varying luting agents and the effectiveness of different cleaning methods (prior to re-cementation) regarding the retentiveness of zirconia copings on implants. MATERIALS AND METHODS. Implants were embedded in resin blocks. Three groups of titanium abutments (pre-fabricated, height: 7.5 mm, taper: $5.7^{\circ}$; customized-long, height: 6.79 mm, taper: $4.8^{\circ}$; customized-short, height: 4.31 mm, taper: $4.8^{\circ}$) were used for luting of CAD/CAM-fabricated zirconia copings with a semi-permanent (Telio CS) and a provisional cement (TempBond NE). Retention forces were evaluated using a universal testing machine. Furthermore, the influence of cleaning methods (manually, manually in combination with ultrasonic bath or sandblasting) prior to re-cementation with a provisional cement (TempBond NE) was investigated with the pre-fabricated titanium abutments (height: 7.5 mm, taper: $5.7^{\circ}$) and SEM-analysis of inner surfaces of the copings was performed. Significant differences were determined via two-way ANOVA. RESULTS. Significant interactions between abutment geometry and luting agent were observed. TempBond NE showed the highest level of retentiveness on customized-long abutments, but was negatively affected by other abutment geometries. In contrast, luting with Telio CS demonstrated consistent results irrespective of the varying abutment geometries. Manual cleaning in combination with an ultrasonic bath was the only cleaning method tested prior to re-cementation that revealed retentiveness levels not inferior to primary cementation. CONCLUSION. No superiority for one of the two cements could be demonstrated because their influences on retentive strength are also depending on abutment geometry. Only manual cleaning in combination with an ultrasonic bath offers retentiveness levels after re-cementation comparable to those of primary luting.

• Journal of the Korean Geosynthetics Society
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• v.23 no.2
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• pp.63-75
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• 2024

Drinking water is an essential element to ensure the basic human right to live, and the quality of clean water must always be ensured. However, domestic water facilities, which were installed intensively in the early 2000s, are deteriorating. The accidents such as discoloration of water such as chromaticity and turbidity as well as leakage of substances frequently occur. However, since it is virtually impossible to replace all water pipes, the detailed standards for maintenance of water pipe network facilities established in 2021 require water pipe cleaning. The swab pig method, one of the water pipe cleaning methods, is a method of physically removing substances in pipes and is evaluated as having the highest cleaning efficiency. However, Swab is highly likely to be damaged or deformed during the cleaning process, and may even be lost. Therefore, in this study, the material of the pig was changed to a material with high compressibility, and it was made as close as possible to the inner wall of the water pipe. And, to maximize cleaning efficiency, a rotation swab pig with a rotation blade was developed. In addition, high-strength wire and winding equipment were additionally developed to eliminate the possibility of loss and to determine the location of the pig. The inlet and outlet are connected with wires, and after verifying the performance of each detailed technology, the technology was applied on a test bed with a 30m section. As a result of the application, the performance of the technology was verified by measuring the process time and evaluating applicability.

• Korean journal of food and cookery science
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• v.24 no.5
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• pp.706-712
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• 2008

This study was conducted to evaluate the sanitation level and use of dish cloths, chopping board, and drawer in the refrigerator in 50 university students' houses located in Seoul and Kyonggido. The survey questionnaire evaluated general information, frequency of the washing, cleaning method, drying method and the associated factors. The highest percentage of the cleaning and drying methods of dish cloths were “boiling(76.0%)”, and “dry in the kitchen or on the sink(78.0%)”, respectively. For the chopping board and drawer in the refrigerator, the highest percentage of cleaning method was “use detergent” and drying method was “dry in the kitchen”. The mean of coliforms for dish cloths, chopping board, and drawer in the refrigerator was 4.46${\pm}$1.95 log CFU/100 $cm^2$, 3.92${\pm}$1.64 log CFU/100 $cm^2$, 3.48${\pm}$2.01 log CFU/ 100 $cm^2$, respectively. Salmonella spp. were not detected from all samples. But E. coli were detected from dish cloths(4.0%) and S. aureus were detected from dish cloths(16.0%), chopping board(12.0%), and drawer in the refrigerator(8.0%). The results of microbiological test of kitchen utensils indicated that the sanitary conditions of dish cloths, chopping board, drawer in the refrigerator should be improve promptly.

• Journal of Information Processing Systems
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• v.19 no.2
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• pp.149-163
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• 2023

Affected by external factors, errors in time series data collected by sensors are common. Using the traditional method of constraining the speed change rate to clean the errors can get good performance. However, they are only limited to the data of stable changing speed because of fixed constraint rules. Actually, data with uneven changing speed is common in practice. To solve this problem, an online cleaning algorithm for time series data based on dynamic speed change rate constraints is proposed in this paper. Since time series data usually changes periodically, we use the extreme learning machine to learn the law of speed changes from past data and predict the speed ranges that change over time to detect the data. In order to realize online data repair, a dual-window mechanism is proposed to transform the global optimal into the local optimal, and the traditional minimum change principle and median theorem are applied in the selection of the repair strategy. Aiming at the problem that the repair method based on the minimum change principle cannot correct consecutive abnormal points, through quantitative analysis, it is believed that the repair strategy should be the boundary of the repair candidate set. The experimental results obtained on the dataset show that the method proposed in this paper can get a better repair effect.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.5
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• pp.674-681
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• 1994

In this study, four kinds of vapor-permeable waterproofed fabrics were selected and their properties and the changes of properties were investigated after laundering, petroleum drycleaning or tetrachloroethylene drycleaning (each 1, 5, 10 times). The results were as follows: 1) In the water resistance, only Gore Tex satisfied its minimum property requirements, $1.0kg/cm^2$ It decreased after laddering and drycleaning. Hipora-1000, Hipora-2000, Aitac decreased slightly by petroleum drycleaning and Gore Tex decreased slightly by all three methods. 2) In the moisture vapor transmission, three except Hipora-2000 satisfied its minimum property requirement, $4000g/m^2{\cdot}24hr$.24hr. After laundering and drycleaning, it increased regardless of cleaning methods. 3) In the water repellency, Hipora-lOOG, Hipora-2000 were not almost decreased after laundering and drycleaning. Aitac decreased slightly by petrolem drycleaning and Gore Tex decreased slightly by laundering and petroleum drycleaning. 4) Air permeability of Aitac increased with increasing of cleaning times regardless of cleaning methods. 5) In the bond strength, only Gore Tex dissatisfied its minimum property requirements, 250g/cm. Regardless of cleaning method, bond strength decreased with increasing of cleaning times. 6) Color difference was large in case of Hipora-1000 by laundering, Hipora-2000 by laundering and tetrachloroethylene drycleaning Aitac by tetrachloroethylene drycleaning, Gore Tex by laundering. To diminish property change of vaper-permeable waterproofed fabric, petroleum drycleaning is more effective than laundering and tetrachloroethylene drycleaning.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.177-184
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• 2011

Membrane fouling is an unavoidable phenomenon in operation of seawater reverse osmosis (SWRO) and major obstacle for economic and efficient operation. When fouling occurs on the membrane surface, the permeate flux is decreased, on the contrary, the trans-membrane pressure (TMP) is increased, therefore operation and maintaining costs and potential damage of membranes are able to the pivotal risks of the process. Chemical cleaning process is essential to prevent interruptions for effective RO membrane filtration process. This study focused on proper chemical cleaning condition for polyamide RO membranes of 4 companies. Several chemical agents were applied for chemical cleaning under numbers of operating conditions. Additionally, a monitoring tool of FEEM as autopsy analysis method is adapted for the prediction of organic bio-fouling.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.66-71
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• 2023

This paper describes a hybrid cleaning method of silicon wafer combining nano-bubble and ultrasound to remove sub-micron particles and contaminants with minimal damage to the wafer surface. In the megasonic cleaning process of semiconductor manufacturing, the cavitation induced by ultrasound can oscillate and collapse violently often with re-entrant jet formation leading to surface damage. The smaller size of cavitation bubbles leads to more stable oscillations with more thermal and viscous damping, thus to less erosive surface cleaning. In this study, ultrasonic energy was applied to the wafer surface in the DI water to excite nano-bubbles at resonance to remove contaminant particles from the surface. A patented nano-bubble generator was developed for the generation of nano-bubbles with concentration of 1×10⁹ bubbles/ml and nominal nano-bubble diameter of 150 nm. Ultrasonic nano-bubble technology improved a contaminant removal efficiency more than 97% for artificial nano-sized particles of alumina and Latex with significant reduction in cleaning time without damage to the wafer surface.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.125-140
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• 2011

The remnant of temporary cement on the intaglio surface of cast restoration may have a negative effect on the retentive strength of permanent cement. This study was to evaluate the effect of temporary cement cleaning methods on the retentive strength of cementation type implant prostheses. Prefabricated implant abutments - height 5.5mm, diameter 4.5mm, 6 degree axial wall taper with chamfer margins were used. Forty copings-abutment specimens were divided into four groups(each n=10) according to the cleaning methods for temporary cement(Temp-$Bond^{(R)}$) as follows : no temporary cementation(the control group), orange solvent, ultrasonic cleaning, air borne-particle abrasion. After the application of temporary cement and the separation, the cleaning procedure was performed according to the protocol of each group. The specimens were cemented with $Premier^{(R)}$ Implant $Cement^{TM}$. After the permanent cementation, the specimens were subjected to thermocycling and pulled out from the specimens with a universal testing machine at a cross-head speed of 0.5mm/min. After the retentive strength test, all the specimens were cleaned using ultrasonic cleaning, abraded with air borne-particles, and steam-cleaned. Likewise, the specimens were temporarily cemented(Temp-$Bond^{(R)}$ NE), cleaned according to the protocol of each group, cemented with $Premier^{(R)}$ Implant $Cement^{TM}$ and subjected to thermocycling and measurement of their retentive strength. The mean of group with orange solvent were significantly lower than those of other groups(p<0.05). There was no significance between group with ultrasonic cleaning and group with air borne-particle abrasion. Group with ultrasonic cleaning and group with air-particle abrasion were no significance at control group. There was no significance between group cemented with Temp-$Bond^{(R)}$ and group cemented with Temp-$Bond^{(R)}$ NE. Within the limitation of this study, it can be concluded that the temporary cement cleaning method with only orange solvent may have a negative effect on the retentive strength of permanent cement. Ultrasonic cleaning and air borne-particle abrasion methods are recommended for the temporary cement cleaning method on cementation type implant prostheses.

• Journal of Korean Society of Steel Construction
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• v.20 no.5
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• pp.583-590
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• 2008

Blasting has been applied in newly-built steel structures for cleaning forged surfaces and increasing the adhesive property of applied painting systems. However, the effect of the blast cleaning on fatigue behavior of welded joints is not clear. In this paper, fatigue tests were carried out on out-of-plane gusset welded joints and the effect of the blast cleaning on the fatigue behavior was studied. The curvature radius at the weld toe of the surface-treated specimens by using the blast method is larger than that of as-welded specimens. By the blast cleaning compressive residual stresses were induced into weld toes. The experimental results showed that the fatigue life of surface-treated specimens is longer than that of as-welded specimens, even though the fatigue life of surface-treated specimens and that of as-welded specimens are not clearly different in the high stress range. About a 160% increase in fatigue limit could be realized by using blast cleaning.