• Korean Journal of Materials Research
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• v.16 no.2
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• pp.75-79
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• 2006

The effect of ozone and/or ultrasound treatments on the efficiency of slurry removal in post sliced cleaning (PSC) of silicon ingot was studied. Efficiency of slurry removal was evaluated as functions of time, temperature and surfactant with DOE (Design of Experiment) method. Residual slurries were observed on the wafer surface in case of cleaning by ozone or ultrasound separately. However, a clean wafer surface was appeared when cleaned with ozone and ultrasound simultaneously. It has found that cleaning time was the main effect among temperature, time and surfactant. Elevated temperature, addition of surfactant and high ozone concentration helped to accelerate efficient removal of slurry. The improvement of removal efficiency seems to be related to the formation of more active OH radicals. The highly cleaned surface was achieved at 10 wt% ozone, 1 min and 10 vol% surfactant with ultrasound. Application of ozone and ultrasound might be a useful method for PSC process in wafer cleaning.

• Wind and Structures
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• v.13 no.5
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• pp.385-412
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• 2010

This article provides a time-resolved characterisation of the wind field in a recently-commissioned, downdraft outflow simulator at The University of Western Ontario. A large slot jet approach to physical simulation was used. The simulator performance was assessed against field observations from a 2002 downdraft outflow near Lubbock, Texas. Outflow wind speed records were decomposed according to classical time series analysis. Length scales, characterising the coarse and fine flow structure, were determined from the time-varying mean and residual components, respectively. The simulated downdraft outflow was approximately 1200 times smaller in spatial extent than the 2002 Lubbock event.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.215-221
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• 1999

The object of the thermal error compensation system in machine tools is improving the accuracy of a machine tool through real time error compensation. The accuracy of the machine tool totally depends on the accuracy of thermal error model. A thermal error model can be obtained by appropriate combination of temperature variables. The proposed method for optimal variable selection in the thermal error model is based on correlation grouping and successive regression analysis. Collinearity matter is improved with the correlation grouping and the judgment function which minimizes residual mean square is used. The linear model is more robust against measurement noises than an engineering judgement model that includes the higher order terms of variables. The proposed method is more effective for the applications in real time error compensation because of the reduction in computational time, sufficient model accuracy, and the robustness.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.9
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• pp.807-813
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• 2016

Recently, a spherical pendulum attached to an end-effector of a robot manipulator has been frequently used for a test bed of residual vibration suppression control in a multi-dimensional motion. However, there was no automatic tracking system to detect the current bob position on-line, and there was inconvenience to not be able to store the bob position in real time and plot the trajectory. In this study, we developed a two-dimensional, real-time bob-detecting system using a digital USB camera, of which the key is hardware component design and software C programming for fast image processing and interfacing. The developed system was applied to residual vibration suppression control of a two-dimensional spherical pendulum that is attached at the end-effector of a two degree-of-freedom SCARA robot, and the effectiveness of the developed system has been demonstrated.

• Analytical Science and Technology
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• v.13 no.1
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• pp.34-40
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• 2000

The optimum conditions for the half-life time and residual analysis of the iminoactadine triacetate fungicide on soils were investigated by using the gas chromatography. Iminoctadine triacetate(IOTA) was extracted from soils with 2.0 M-NaOH/methanol and chloroform. The extracted IOTA was derivatized to pyrimidine hexafluroacetylacetone by the acetylation and analyzed with GC/ECD after elimination of moisture and impurities on the Sep-Pak column. From the standard addition experiments with 0.1 and 1.0 ppm, the average recoveries were ranged from 83.8 to 93.2 % and the detection limit was 0.005 ppm. The half-life time of iminoctadine triacetate in the silty clay was 30 days in the laboratory and 19.5 days in the field test whereas it was 27 days and 17.5 days for each in case of silty loam.

• Steel and Composite Structures
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• v.50 no.4
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• pp.383-401
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• 2024

The research comprehensively studies the axial compression performance of T-shaped concrete-filled thin-walled steel tubular (CTST) long columns after fire exposure. Initially, a series of tests investigate the effects of heating time, load eccentricity, and stiffeners on the column's performance. Furthermore, Finite Element (FE) analysis is employed to establish temperature and mechanical field models for the T-shaped CTST long column with stiffeners after fire exposure, using carefully determined key parameters such as thermal parameters, constitutive relations, and contact models. In addition, a parametric analysis based on the numerical models is conducted to explore the effects of heating time, section diameter, material strength, and steel ratio on the axial compressive bearing capacity, bending bearing capacity under normal temperature, as well as residual bearing capacity after fire exposure. The results reveal that the maximum lateral deformation occurs near the middle of the span, with bending increasing as heating time and eccentricity rise. Despite a decrease in axial compressive load and bending capacity after fire exposure, the columns still exhibit desirable bearing capacity and deformability. Moreover, the obtained FE results align closely with experimental findings, validating the reliability of the developed numerical models. Additionally, this study proposes a simplified design method to calculate these mechanical property parameters, satisfying the ISO-834 standard. The relative errors between the proposed simplified formulas and FE models remain within 10%, indicating their capability to provide a theoretical reference for practical engineering applications.

• Journal of Korea Water Resources Association
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• v.57 no.3
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• pp.151-164
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• 2024

In water treatment plants supplying potable water, the management of chlorine concentration in water treatment processes involving pre-chlorination or intermediate chlorination requires process control. To address this, research has been conducted on water quality prediction techniques utilizing AI technology. This study developed an AI-based predictive model for automating the process control of chlorine disinfection, targeting the prediction of residual chlorine concentration downstream of sedimentation basins in water treatment processes. The AI-based model, which learns from past water quality observation data to predict future water quality, offers a simpler and more efficient approach compared to complex physicochemical and biological water quality models. The model was tested by predicting the residual chlorine concentration downstream of the sedimentation basins at Plant, using multiple regression models and AI-based models like Random Forest and LSTM, and the results were compared. For optimal prediction of residual chlorine concentration, the input-output structure of the AI model included the residual chlorine concentration upstream of the sedimentation basin, turbidity, pH, water temperature, electrical conductivity, inflow of raw water, alkalinity, NH₃, etc. as independent variables, and the desired residual chlorine concentration of the effluent from the sedimentation basin as the dependent variable. The independent variables were selected from observable data at the water treatment plant, which are influential on the residual chlorine concentration downstream of the sedimentation basin. The analysis showed that, for Plant, the model based on Random Forest had the lowest error compared to multiple regression models, neural network models, model trees, and other Random Forest models. The optimal predicted residual chlorine concentration downstream of the sedimentation basin presented in this study is expected to enable real-time control of chlorine dosing in previous treatment stages, thereby enhancing water treatment efficiency and reducing chemical costs.

• Journal of Bio-Environment Control
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• v.33 no.1
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• pp.30-36
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• 2024

This study was conducted to determine the optimal working conditions when a recently developed blower-type onion stem cutter is utilized for cutting onion leaves at harvest time. The June 20 leaf cutting treatment group had the highest leaf dryness among the treatment groups (leaf dryness: 66.3%; leaf moisture content: 50.5%); the residual leaf length was 6.7 ± 3.5 cm. It is considered to have the best mechanical leaf cutting performance among the treatment groups because it is included in the optimal range of 4-10 cm. The average working speed of mechanical onion leaf cutting using the stem cutter was 0.17 m·s^-1, which is approximately 3.4 times faster than the average working speed of 0.05 m·s^-1 in the human leaf cutting treatment group. This is expected to save approximately 2.6 hours compared to human labor (based on one person) when working on a 10a area using this machine. In addition, the incidence of damaged bulbs in the machine leaf cutting treatment group was 1.3%, compared to 0.0% in the manual leaf cutting treatment group. This suggests that the mechanical leaf cutting treatment group had a higher average onion bulb decay rate during storage than the manual leaf cutting treatment group. When the storage characteristics of each treatment group were examined, the decay rate by bulb part (leaf connected or root connected) after 8 months of storage was higher in the treatment group with a residual leaf length of less than 5.0 cm after mechanical leaf cutting than in the treatment with a residual leaf length of more than 5.0 cm. This is thought to be due to the fact that treatments with a residual leaf length of less than 5.0 cm are more susceptible to infection by pathogens that cause decay during storage than treatments with a residual leaf length of 5.0 cm or more. Based on the results of this experiment, performance target of the experimental machine (residual leaf length after operation: 5 cm), and existing research on the optimal residual leaf length for onion harvesting, it is recommended to cut onion leaves so that the residual leaf length is 5-10 cm when using the stem cutter.

• Tuberculosis and Respiratory Diseases
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• v.59 no.1
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• pp.69-76
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• 2005

Background : Residual pleural thickening (RPT) is the most common complication of tuberculous pleurisy (TP), despite adequate anti-tuberculous chemotherapy. At the conclusion of treatment, 43-50% of patients present RPT, with its incidence varying according to the time of evaluation. To assess the spontaneous resolution of RPT, the RPT at the completion of treatment was compared with that at the final follow-up. The factors related to the development of RPT after the completion of treatment were also studied. Methods : The medical records of sixty four patients, diagnosed with TP between March 2001 and June 2003, were retrospectively. The RPT was measured at the completion of treatment and at the time of the final follow-up and the degree and frequency of RPT compared between the two measurements. Each time, the patients were divided into two groups: those with and without RPT. The clinical characteristics and the radiographic and pleural fluid findings of the two groups were compared. Results : Thirty six (56%) and 27 patients had RPT at the completion of treatment and at the time of the final follow-up, respectively (median follow up period: 8 months). Spontaneous resolution of the RPT was found in 9 patients (24%), and had decrease below 10mm in 15 (42%) during the follow-up period after treatment. The patients were initially divided into two groups: 36 and 27 patients with and without RPT, respectively. There was no predicting factor of RPT, with the exception of the presence of CRP, between the two groups. The patients were also separated into two groups at the time of final visit: 27 and 37 patients with and without RPT, respectively. The patients with RPT were found to have a lower total WBC count in pleural fluid. Conclusion : 57% of patients with RPT were found to have spontaneous resolution of the residual pleural thickening after completion of the chemotherapy. The time of evaluation for RPT and its predicting factors were decided after adequate follow-up, irrespective of the completion of treatment.

• Horticultural Science & Technology
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• v.34 no.1
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• pp.77-83
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• 2016

The measurement of total fresh weight of plants provides an essential indicator of crop growth for monitoring production. To measure fresh weight without damaging the vegetation, image-based methods have been developed, but they have limitations. In addition, the total plant fresh weight is difficult to measure directly in hydroponic cultivation systems because of the amount of nutrient solution. This study aimed to develop a real-time, precise method to measure the total fresh weight of Romaine lettuce (Lactuca sativa L. cv. Asia Heuk Romaine) with growth stage in a plant factory using a nutrient film technique. The total weight of the channel, amount of residual nutrient solution in the channel, and fresh shoot and root weights of the plants were measured every 7 days after transplanting. The initial weight of the channel during nutrient solution supply (Wi) and its weight change per second just after the nutrient solution supply stopped were also measured. When no more draining occurred, the final weight of the channel (Ws) and the amount of residual nutrient solution in the channel were measured. The time constant (${\tau}$) was calculated by considering the transient values of Wi and Ws. The relationship of Wi, Ws, ${\tau}$, and fresh weight was quantitatively analyzed. After the nutrient solution supply stopped, the change in the channel weight exponentially decreased. The nutrient solution in the channel slowly drained as the root weight in the channel increased. Large differences were observed between the actual fresh weight of the plant and the predicted value because the channel included residual nutrient solution. These differences were difficult to predict with growth stage but a model with the time constant showed the highest accuracy. The real-time fresh weight could be calculated from Wi, Ws, and ${\tau}$ with growth stage.