• Journal of the Institute of Convergence Signal Processing
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• v.23 no.1
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• pp.1-7
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• 2022

As a power transmission element, the timing belt is a toothed transmission belt that takes advantages of V-belts and gears. It has characteristics of non-slip and low noise. It is used as a power transmission device when transmitting power from a rotating shaft or linear motion in a mechanism. Rotation can be accurately transmitted through a belt pulley with grooves like a gear and a timing belt with grooves to precisely match with the belt pulley. In particular, in the mechanism in which the timing belt is used for the output shaft, the dynamic characteristics including the rigidity of the timing belt determine the transmission characteristics of the system, so its importance increases. In this paper, a stiffness reinforced belt that can be applied to a timing belt with a limited range of motion to increase its stiffness is proposed. To study the dynamic characteristics of the stiffness reinforced belt, the equation of motion for the stiffness reinforced belt was established, and a simulation model for the stiffness reinforced belt was created and analyzed. In order to confirm the analysis results of the motion equation and simulation model, a 1-axis rotation experimental equipment using a stiffness reinforcing belt was developed and the experiment was conducted. Through motion equations, simulation models, and experiment results, it was confirmed that the stiffness and dynamic characteristics of the timing belt could be improved by applying the proposed stiffness reinforcement belt.

• Journal of the Korean GEO-environmental Society
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• v.23 no.1
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• pp.39-49
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• 2022

Expandable steel pipe piles are installed by inserting expansion equipment to increase the cross-sectional area of steel pipes, which can improve the pile performance compared to micro-piles. In this paper, a hydraulic expansion device was developed to expand steel pipe piles in practice. A series of laboratory and field tests were conducted to verify the performance of the developed expansion device to expand steel pipes. The expansion capability and expandable range was evaluated by measuring the strain and expansion time at the maximum pressure of the hydraulic expansion device. The thinner steel pipe, the larger strain but longer expansion time required in the test. For example, the 4.0-mm-thick steel pipe showed strain reduction by 30% and a decrease in the required expansion time by 40% compared to the 2.9-mm-thick steel pipe. In addition, in-situ expansion tests were performed to verify the expandability of steel pipes under the ground, and the exhumed specimen showed clear expanded sections. The structural integrity was determined by comparing the material performance the original and expanded specimens.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.69-77
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• 2022

Physical experiment through MBL has been used in many schools for a long time since students can check the experiment results immediately and conduct the experiment easily. However, conducting the experiment, not knowing the principle of the device or simply concentrating on the derived data has been raised as the problem of MBL experiment. To supplement this problem, this study measured the acceleration of gravity with the picket fence method, which is often used in MBL experiment, utilizing Arduino, calculated the error rate through a comparison to the actual acceleration of gravity and discussed the educational application of the experiment to measure it. As a result of the experiment, the error rate between the acceleration of gravity calculated by the experiment and the actual acceleration of gravity was about 1%, so it turned out that relatively accurate measurements were possible. Also, the sample mean of the experimental value was included in the confidence interval of 95%, so it could be concluded that it was a significant experiment. In addition, this study showed the possibility of the educational application of the experiment to measure it through the following: It can supplement the structural disadvantages of MBL; it can consider the interaction between Physics and Math; it is possible to converge with information course in STEAM education; and it is inexpensive to be equipped with the equipment. Hopefully, the physical experiment utilizing Arduino will further be revitalized in science gifted education based on this study.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.23-29
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• 2023

Microfluidic reactors have been made to achieve significant development for the generation of new functional materials to apply in a variety of fields. Over the last decade, microfluidic reactors have attracted attention as a user-friendly approach that is enabled to control physicochemical parameters such as size, shape, composition, and surface property. Here, we develop a centrifugal microfluidic reactor that can control the flow of fluid based on centrifugal force and generate multifunctional particles of various sizes and compositions. A centrifugal microfluidic reactor is fabricated by combining microneedles, micro- centrifuge tubes, and conical tubes, which are easily obtained in the laboratory. Depending on the experimental control param- eters, including centrifuge rotation speed, alginate concentration, calcium ion concentration, and distance from the needle to the calcium aqueous solution, this strategy not only enables the generation of size-controlled microparticles in a simple and reproducible manner but also achieves scalable production without the use of complicated skills or advanced equipment. Therefore, we believe that this simple strategy could serve as an on-demand platform for a wide range of industrial and academic applications, particularly for the development of advanced smart materials with new functionalities in biomedical engineering.

• Journal of the Korean Geotechnical Society
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• v.38 no.5
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• pp.35-46
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• 2022

The in-situ resource utilization (ISRU) for sustainable lunar surface and deep space explorations has recently gained attention. Also, research on the development of construction material preparation technology using lunar regolith is in progress. Microwave sintering technology for construction material preparation does not require a binder and is energy efficient. This study applies microwave sintering technology to KLS-1, a Korean lunar simulant. It is crucial to secure the homogeneity to produce a sintered specimen for construction material. Therefore, understanding the interactions between microwaves, cavities, and raw materials is required. Using a numerical model in terms of efficient assessment of several cases and establishment of equipment operating conditions is a very efficient approach. Therefore, this study also proposes and verifies a coupled electric-thermal numerical model through cross-validation and comparison with experimental results. The numerical model proposed in this study will be used to present an efficient method for producing construction material using microwave sintering technology.

• Journal of the Korea Society of Computer and Information
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• v.27 no.9
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• pp.1-12
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• 2022

Traditional methods of measuring corneal ulcers were difficult to present objective basis for diagnosis because of the subjective judgment of the medical staff through photographs taken with special equipment. In this paper, we propose a method to detect the ulcer area on a pixel basis in corneal ulcer images using a semantic segmentation model. In order to solve this problem, we performed the experiment to detect the ulcer area based on the DeepLab model which has the highest performance in semantic segmentation model. For the experiment, the training and test data were selected and the backbone network of DeepLab model which set as Xception and ResNet, respectively were evaluated and compared the performances. We used Dice similarity coefficient and IoU value as an indicator to evaluate the performances. Experimental results show that when 'crop & resized' images are added to the dataset, it segment the ulcer area with an average accuracy about 93% of Dice similarity coefficient on the DeepLab model with ResNet101 as the backbone network. This study shows that the semantic segmentation model used for object detection also has an ability to make significant results when classifying objects with irregular shapes such as corneal ulcers. Ultimately, we will perform the extension of datasets and experiment with adaptive learning methods through future studies so that they can be implemented in real medical diagnosis environment.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.11
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• pp.449-456
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• 2021

An intrusion detection system is a technology that detects abnormal behaviors that violate security, and detects abnormal operations and prevents system attacks. Existing intrusion detection systems have been designed using statistical analysis or anomaly detection techniques for traffic patterns, but modern systems generate a variety of traffic different from existing systems due to rapidly growing technologies, so the existing methods have limitations. In order to overcome this limitation, study on intrusion detection methods applying various machine learning techniques is being actively conducted. In this study, a comparative study was conducted on data preprocessing techniques that can improve the accuracy of anomaly detection using NGIDS-DS (Next Generation IDS Database) generated by simulation equipment for traffic in various network environments. Padding and sliding window were used as data preprocessing, and an oversampling technique with Adversarial Auto-Encoder (AAE) was applied to solve the problem of imbalance between the normal data rate and the abnormal data rate. In addition, the performance improvement of detection accuracy was confirmed by using Skip-gram among the Word2Vec techniques that can extract feature vectors of preprocessed sequence data. PCA-SVM and GRU were used as models for comparative experiments, and the experimental results showed better performance when sliding window, skip-gram, AAE, and GRU were applied.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.5
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• pp.357-371
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• 2023

In cable tunnel construction using TBM, the vertical shaft is an essential structure for entrance and exit of TBM equipment and power lines. Since a shaft penetrates the ground vertically, it often encounters rock mass. Blasting or rock splitting methods, which are mainly used to the rock excavation, cause public complaints due to the noise, vibration and road occupation. Therefore, mechanical excavation using vertical shaft excavation machine are considered as an alternative to the conventional methods. However, at the current level of technology, the vertical excavation machine has limitation in its performance when applied for high strength rock with a compressive strength of more than 120 MPa. In this study, the potential utilization of waterjet technology as an excavation assistance method was investigated to improve mechanical excavation performance in the hard rock formations. Rock cutting experiments were conducted to verify the cutting performance of the abrasive waterjet. Based on the experimental result, it was found that ensuring excavation performance with respect to changing in ground conditions can be achieved by adjusting waterjet parameters such as standoff distance, traverse speed and water pressure. In addition, based on the relationship between excavation performance, uniaxial compressive strength and RQD, it was suggested that excavation performance could be improved by artificially creating joints using the abrasive waterjet. It is expected that these research results can be utilized as fundamental data for the introduction of vertical shaft excavation machines in the future.

• Journal of the Institute of Convergence Signal Processing
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• v.23 no.3
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• pp.115-122
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• 2022

With the outbreak of COVID-19 a few years ago, video conferencing and electronic document work have increased, and for this reason, the proportion of computer work among modern people's daily routines is increasing. However, as more and more people work on computers in the wrong posture for a long time, the number of patients with poor eyesight and text neck is increasing. Until recently, many studies have been published to correct posture, but most of them have limitations that users may experience discomfort because they have to correct posture by wearing equipment. A posture correction sensor algorithm is proposed to prevent access to the minimum distance between a computer monitor and a person using an ultrasonic sensor device. At this time, an algorithm for minimizing false alarms among warning alarms that sound at the minimum distance is also proposed. Because the ultrasonic sensor device is used, posture correction can be performed without attaching a device to the body, and the user can relieve discomfort. In addition, experimental results showed that accuracy can be improved by reducing false alarms by removing more than half of the noise generated during distance measurement.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.1-9
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• 2009

When a rock slope is excavated adjacent to a existing tunnel, the behavior of the existing tunnel in the jointed rock masses is greatly influenced by the joint conditions and slope status. In this study, the effects of joint dip and slope angle close to a tunnel are investigated through a large scale model using a biaxial test equipment ($3.1\;m\;{\times}\;3.1\;m\;{\times}\;0.50\;m$ (width $\times$ height $\times$ length)). The jointed rock masses were built by concrete blocks. The diameter of the modeled tunnel is 0.6 m and the dip angles of joint vary in the range of $0-90^{\circ}$. In addition, the excavated slope angle varies within $30{\sim}90^{\circ}$. Deformational behaviors of the tunnel were analyzed in consideration of joint dip and slope angle. With increase of the joint dip and slope angle, the magnitude of tunnel distortion and the moment of tunnel lining were increased. Rock mass displacement in horizontal was also dependent on the joint dip and the excavated slope angle, which indicated the optimal slope reinforcement for a specific rock mass conditions.