• Journal of Powder Materials
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• v.26 no.5
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• pp.369-374
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• 2019

The properties of powder metallurgy products are related to their densities. In the present work, we demonstrate a method to apply artificial neural networks (ANNs) trained on experimental data to predict the bulk density of barium titanates. The density is modeled as a function of pressure, press rate, heating rate, sintering temperature, and soaking time using the ANN method. The model predictions with the training and testing data result in a high coefficient of correlation (R2 = 0.95 and Pearson's r = 0.97) and low average error. Moreover, a graphical user interface for the model is developed on the basis of the transformed weights of the optimally trained model. It facilitates the prediction of an infinite combination of process parameters with reasonable accuracy. Sensitivity analysis performed on the ANN model aids the identification of the impact of process parameters on the density of barium titanates.

• Journal of the Korean Society of Visualization
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• v.17 no.1
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• pp.43-52
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• 2019

'Ionic wind' is phenomenon induced by corona discharge which occurs when large electric potential is applied to electrodes with high curvature. The ionic wind has advantage that it could generate forced convective flow without any external energy like separate pump. In this study, 'pin-mesh' arrangement is utilized for experiments. First, optimization of configuration is conducted with local momentum of ionic wind behind the mesh. Empirical equation for prediction about velocity profile was derived using the measured results. Secondly, the enhancement of mass transfer rate of acetone with ionic wind was analyzed. Also, the drying efficiency using a fan which has same flow rate was compared with ionic wind for identification of additional chemical reaction. At last, the drying process of organic solvent was visualized with image processing. As a result, it was shown that the use of ionic wind could dry organic matter four times faster than the natural condition.

• Environmental Engineering Research
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• v.24 no.2
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• pp.298-308
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• 2019

This work deals with the membrane fouling mode and the unclogging in seawater ultrafiltration process. The identification of the fouling mechanism by modeling the experimental flux decline was performed using both the classical models of Hermia and the combined models of Bolton. The results show that Bolton models did not bring more precise information than the Hermia's and the flux decline can be described by one of the four Hermia's models since the backwash interval is ${\leq}60$ min. An experimental screening study has been then conducted to choose among 5 parameters (backwash interval, duration, pulses and the flow-rate or injected hypochlorite concentration) those that are the most influential on the fouling and the net water production. It has emerged that fouling is mainly affected by the backwash interval; its prolongation from 30 to 60 min engenders an increase in the reversible fouling and a decrease in the irreversible fouling. This later is also significantly reduced when the hypochlorite concentration increases from 4.5 to 10 ppm. Moreover, the net water production significantly increases with increasing the filtration duration up to 60 min and decreases with decreasing the backwash duration and backwash flow-rate from 10 to 40 s and from 15 to ${\geq}20L.min^{-1}$, respectively.

• Biomedical Science Letters
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• v.27 no.2
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• pp.45-50
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• 2021

Coagulase-negative staphylococci (CoNS) are a typical group of microorganisms, and the recent advances in laboratory technology and medicine has dramatically modified their significance in medical practice. CoNS, which were previously classified as normal bacterial flora, have recently been reported to be associated with serious infectious diseases, such as surgical wound infection or periprosthetic joint infection. Representative CoNS include Staphylococcus epidermidis, S. haemolyticus, and S. saprophyticus, which are known to cause serious problems in biomaterial-based and prosthetic device infections, as well as to cause simple urinary tract infections in sexually active women. Over the last decade, the clinical isolation rate of CoNS has been increasing, and antibiotic resistance has also been occurring. This review aimed to investigate the incidence of CoNS infection and to use the results as basic data for the management of CoNS, with a focus on the isolation rate and antibiotic resistance in clinical surgery.

• Tuberculosis and Respiratory Diseases
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• v.84 no.2
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• pp.89-95
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• 2021

Lung cancer is one of the leading causes of cancer-related deaths in Korea. Although the smoking rate has decreased over time, the prevalence of lung cancer still remains high. In this study, we reviewed recent trends on the incidence, epidemiology, screening, diagnosis, and treatment of lung cancer in Korea by analyzing data from the national lung cancer registry and recently-published studies. Although approximately 40% of patients with non-small cell lung cancer (NSCLC) were diagnosed as stage IV, the 5-year relative survival rate improved from 11.3% (1993-1995) to 30.2% (2013-2017), possibly due to advances in methods of diagnosis and therapy. In addition, the 2019 implementation of the national lung cancer screening program with low-dose computed tomography may have also contributed to these improvements in survival rates. Recently, molecular diagnosis has become more widely used in the identification of genetic mutations in tissue specimens. Target therapy and immune checkpoint inhibitors have also been successfully used, particularly in cases of advanced NSCLC. In the future, further research on the optimal management of lung cancer remains necessary.

• Journal of the Korea Safety Management & Science
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• v.24 no.2
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• pp.25-32
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• 2022

The rate of industrial accident reduction is slowing down as the attention of the Ministry of Employment and Labor and related agencies on risk assessment systems decreased. this paper focuses on weakness of legal system for the risk assessment in recent years. A survey was conducted to identify the status and condition of the risk assessment system applying on small and medium-sized manufacturing companies. A set of questionnaires is designed to reflect various perspectives of the companies regarding the problems and solutions of the system. The results refer that differentiated instructions and support systems in response to the actual conditions of the companies are mandatory to reinforce the efficiency of risk assessment system.

• Korean Journal of Construction Engineering and Management
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• v.25 no.2
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• pp.69-80
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• 2024

Currently rebar spacing inspection is carried out by human inspectors who heavily rely on their individual experience, lacking a guarantee of objectivity and accuracy in the inspection process. In addition, if incorrectly placed rebars are identified, the inspector need to correct them. Recently, laser scanning and AR technologies have been widely used because of their merits of measurement accuracy and visualization. This study proposes a technology for rebar spacing inspection and fixing by combining laser scanning and AR technology. First, scan data acquisition of rebar layers is performed and the raw scan data is processed. Second, AR-based visualization and fixing are performed by comparing the design model with the model generated from the scan data. To verify the developed technique, performance comparison test is conducted by comparing with existing drawing-based method in terms of inspection time, error detection rate, cognitive load, and situational awareness ability. It is found from the result of the experiment that the AR-based rebar inspection and fixing technology is faster than the drawing-based method, but there was no significant difference between the two groups in error identification rate, cognitive load, and situational awareness ability. Based on the experimental results, the proposed AR-based rebar spacing inspection and fixing technology is expected to be highly useful throughout the construction industry.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.813-821
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• 2000

The engineering of satellite communication systems at frequencies above 10GHz requires a method for estimating rain-caused outage probabilities on the earth-satellite path. A procedure for predicting a rain attenuation distribution from a point rainfall rate distribution is, therefore, needed. In order to predict rain attenuation on the satellite link, several prediction models such as ITU-R, Global, SAM, DAH model, have been developed and used at a particular propagation condition, they may not be appropriate to a propagation condition in Korean territory. In this paper, a new rain attenuation prediction method appropriate to a propagation condition in Korea is introduced. Based on the results from ETRI measurements, a new method has been derived for an empirical approach with an identification on the horizontal correction factor as in current ITU-R method, and the vertical correction factor has been suggested with decreasing power law as a function of rainfall rate. This proposed model uses the entire rainfall rate distribution as input to the model, while the ITU-R and DAH model approaches only use a single 0.01% annual rainfall rate and assume that the attenuation at other probability levels can be determined from that single point distribution. This new model was compared with several world-wide prediction models. Based on the analysis, we can easily know the importance of the model choice to predict rain attenuation for a particular location in the radio communication system design.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.195-197
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• 2001

The shorted-turn sensor for generator's field winding has been developed. The sensor, installed in the generator air-gap, senses the slot leakage flux of field winding and produces a voltage waveform proportional to the rate of change of the flux. For identification of reliability for sensor, a shorted-turn test was performed at the Seoinchon & Sininchon combined cycle power plant on gas turbine generator. This sensor will be used as a detecting of shorted-turn for generator's field winding.

• The Journal of Korean Medicine
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• v.34 no.1
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• pp.179-191
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• 2013

Kleine-Levin syndrome is a rare disorder characterized by recurrent episodes of hypersomnia, hyperphagia, hypersexuality and delusion and hallucination with spontaneous recovery. A 17-year-old female suddenly showed hypersomnia, severe fatigue, and compulsive hyperphagia. She was diagnosed with suspected Kleine-Levin Syndrome. The precipitating factor was an upper respiratory tract infection that the patient had undergone 2 weeks prior. Past psychiatric history included somnambulism and ADHD; her symptoms of ADHD included attention deficit, impulsiveness, hyperactivity, and irritability. This was her third episode. Her hypersomnia was longer in duration but lower in frequency compared with usual KLS. Her low LF/HF ratio in heart rate variability measurement showed high parasympathetic nerve activity. A MMPI report showed some psychological problem. The patient was diagnosed of gastric fever by pattern identification. Her hypersomnia episode improved 6 weeks after onset. This is the first reported case of suspected Kleine-Levin Syndrome in the field of Oriental Medicine in Korea.