• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.375-376
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• 2012

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2005.09a
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• pp.78-79
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• 2005

• Journal of the Semiconductor & Display Technology
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• v.22 no.1
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• pp.1-5
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• 2023

Most of the production process is performed in a cleanroom in the case of facilities that produce semiconductor chips or display panels. Therefore, environmental management of cleanrooms is very important for product yield and quality control. Among them, airborne particles are a representative management item enough to be the standard for the actual cleanroom rating, and it is a part of the Fab or Facility monitoring system, and the sequential particle monitoring system is mainly used. However, this method has a problem in that measurement efficiency decreases as the length of the sampling tube increases. In addition, a statistically significant test of deterioration in efficiency has rarely been performed. Therefore, in this study, the statistically significant test between the number of particles measured by InSitu and the number of particles measured for each sampling tube ends(Remote). Through this, the efficiency degradation problem of the sequential particle monitoring system was confirmed by a statistical method.

• Smart Structures and Systems
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• v.20 no.1
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• pp.43-52
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• 2017

Structural health monitoring has drawn great attention in the field of civil engineering in past two decades. These structural health monitoring methods evaluate structural integrity through high-quality sensor measurements of structures. Due to electronic deterioration or aging problems, sensors may yield biased signals. Therefore, the objective of this study is to develop a fault detection method that identifies malfunctioning sensors in a sensor network. This method exploits the autoregressive modeling technique to generate a bank of Kalman estimators, and the faulty sensors are then recognized by comparing the measurements with these estimated signals. Three types of faults are considered in this study including the additive, multiplicative, and slowly drifting faults. To assess the effectiveness of detecting faulty sensors, a numerical example is provided, while an experimental investigation with faults added artificially is studied. As a result, the proposed method is capable of determining the faulty occurrences and types.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.619-624
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• 2004

In this research, the structural health monitoring method using wavelet packet analysis and artificial neural network (ANN) is developed. Wavelet packet Transform (WPT) is applied to the response acceleration of a 3 element-cantilever beam which is subjected to impulse load and Gaussian random load to decompose the response signal, then the energy of each component is calculated. The first ten largest components in magnitude among the decomposed components are selected as input to an ANN to identify the damage location and severity. This method successfully predicted the amount of damage in the structure when the structure is subjected to impulse load. However, when the beam is subjected to Gaussian random load which can be considered as ambient vibration it did not yield satisfactory results. This method is applicable to structures such as machinery gears that are subjected to repetitive loads.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.182-192
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• 2014

Objectives: The aim of this study is to analyze the current status of possession of measurement and analytical instruments at work environment monitoring organizations and their relationships with human resources, including the number of professional engineers and evaluation scores resulting from evaluation programs in 2012. Materials: Data for measurement and analytical instruments were gathered by inspectors who had been assigned by the Korea Occupational Safety and Health Agency(KOSHA) and the Ministry of Employment and Labor(MoEL) during the evaluation program for 2012. Data for 11 monitoring instruments and nice pieces of analytical equipment were collected from 103 organizations. Additional data such as the type of service provides and the number of professional engineers employed were also recorded by the inspectors. Evaluation scores could be acquired from KOSHA. Results: Comprehensive Occupational Health Service Providers showed good operation quality, while University or Hospital Subsidiary and Work Environment Monitoring Organizations recorded relatively poor results. Evaluation scores correlated well with the possession of measurement instruments and human resources for each organization. High yields provided by professional engineers also showed statistically-associated contributions to evaluation scores and monitoring instrument possession. Compared with monitoring instruments, the amount of analytical equipment had little positive impact on organizations' competence. Conclusions: The evaluation results for domestic monitoring organizations revealed that human resources, possession of instruments, and the quality of employees were critical factors for operating the corporations. Each organization should give considerable effort to improving their ability to strengtheninternal quality, resulting in high-yield production for workers and employers by providing improved workplace monitoring services.

• Journal of IKEEE
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• v.23 no.1
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• pp.22-28
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• 2019

This paper presents the monitoring method of machining error and quality check to improve the productivity of boring manufacturing process. Machining error usually appears as the offset of spatial location of actual cutting path compared to ideal cutting path. In order to monitor an error of workpiece, multiple factors affecting quality of boring, such as distortion of workpiece, clamping error, radial rotation error of the spindle and motion error of machine tools, were took into account. To verify the productive quality, we propose the quality check system. The system based on IT convergence analyzes the process error rate and saves the analyzed data in memory. Also, these play important roles in detecting an inferior production goods and can decrease the production cost and loss of bearing.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.353-353
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• 2017

Rice yield of South Korea in 2015 was the highest of the last 30 years. It is important issue to establish food policy whether the historically highest yield in 2015 can be continued or just one-off event. Therefore, it is necessary to understand whether such a high yield as 2015 will be reoccurred. The aim of this study was to find out what climatic factor affect rice yield and how often these climatic factor could occur. For this study, the yield monitoring data from National Institute of Crop Science, Rural Development Administration and the meteorological data provided by Korea Meteorological Administration are used to identify the weather conditions could cause high yield, and how often these conditions occurred in the past. Our results indicated that such as high yield as 2015 could occur only when the mean sunshine hours of July and the mean sunshine hours from the end of August to early September was more than 5.1 hours and 6 hours, respectively. Mean sunshine hour of July may be related to grain number. The mean sunshine hour from the end of August to early September was presumed to relate to grain filling ratio. The relationship between monthly mean temperature and yield or yield component was not clear in this study. In this study, any cycle of high weather condition was not found. Therefore, the probability of high yield weather condition was expressed by frequency. The frequency of the sunshine hour, could make high yield, were 8/35 (23%) over the past 35 years. And the frequency of two years consecutive sunshine hour condition, which could cause high yield, was 1/35 (2.9%). The frequency of recurrence of sunshine hour making high yield within the next 5 years or 10 years after high yield weather condition were 4/35 (11.4%). After all, the high yield as much as yield of 2015 could not be one-off event. But it was not also consecutive event.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.370-377
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• 2000

The red ginseng is very popular as a health food. It has been manufactured with raw ginseng by the conventional method. But, the yield of the heaven grade ginseng (the best quality red ginseng) among the whole products is around 5-7％, Therefore, the yield should be improved in order to increase economic returns. In this study, a new model of drying system was developed to improve the yield of heaven grade ginseng from 7% to 15% or more. For this system, temperature and relative humidity were controlled by the feedback control system, and a solenoid valve for steam supply and other variables were controlled by the PC. The special features of this system developed are an image processing system for monitoring the red ginseng during the drying process in the drying chamber, and a cylindrical porous tray for holding ginseng that is rotating with the speed of 0-10rpm in the drying chamber and makes uniform drying of red ginseng possible.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.1
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• pp.87-97
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• 2004

The paper presents the results from the applications of the Water Erosion Prediction Project (WEPP) model to a single plot, and also a small watershed in the Mid Korean Peninsula which is comprised of hillslopes and channels along the water courses. Field monitoring was carried out to obtain total runoff, peak runoff and sediment yield data from research sites. For the plot of 0.63 ha in size, cultivated with com, the relative error of the simulated total runoff, peak runoff rates, and sediment yields using WEPP ranged from -16.6 to 22％, from -15.6 to 6.0％, and from 23.9 to 356.4％ compared to the observed data, respectively. The relative errors for the upland watershed of 5.1 ha ranged from -0.7 to 11.1 ％ for the total runoff, from -6.6 to 35.0 ％ for the sediment yields. The simulation results seem to justify that WEPP is applicable to the Korean dry croplands if the parameters are correctly defined. The results from WEPP applications showed that the major source areas contributing sediment yield most are downstream parts of the watershed where runoff concentrated. It was suggested that cultural practice be managed in such a way that the soil surface could be fully covered by crop during rainy season to minimize sediment yield. And also, best management practices were recommended based on WEPP simulations.