• Journal of Dental Anesthesia and Pain Medicine
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• v.20 no.6
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• pp.397-402
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• 2020

Background: Inferior alveolar nerve block (IANB) is the most common, painful, and anxiety-provoking procedure involving needle insertion for anesthetic solution deposition. DentalVibeⓇ (DV) delivers vibration at a sustained frequency as a counter-stimulation to the site of injection, thereby alleviating pain. The aim of this study was to evaluate and compare the effectiveness of DV and lignocaine hydrochloride 2% gel (Lox 2% jelly) in pain reduction during IANB in children. Methods: A split-mouth randomized clinical trial was designed with a sample of 60 children (age, 6 to 12 years) requiring bilateral IANB for various dental procedures; DV was used while administering IANB and Lox 2% jelly was used as the topical anesthetic before administering IANB at subsequent appointments. During both appointments, pain perception was measured using the sound, eye, motor (SEM) scale and Wong-Baker faces pain rating scale (WBFPRS); oxygen saturation (SpO2) and pulse rate were measured using a pulse oximeter before, during, and after the IANB procedure. The obtained values were tabulated and subjected to statistical analysis. Wilcoxon test was used for intergroup comparison, and Friedman test, for intragroup comparison of measured variables at different treatment phases. Results: The medians and interquartile ranges of the WBFPRS scores recorded during the IANB procedure for DV and Lox 2% jelly were 2 (2-4) and 2 (0-2), respectively (P < 0.05). The SEM scale scores, mean SpO2, and pulse rate did not show any significant differences during the IANB procedure between both treatments. Conclusion: Both DV and Lox 2% jelly were found to be effective in pain reduction during IANB in children.

• Fashion & Textile Research Journal
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• v.24 no.5
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• pp.647-654
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• 2022

Wearable devices come in a variety of shapes and sizes in numerous fields in numerous fields and are available in various forms. They can be integrated into clothing, gloves, hats, glasses, and bags and used in healthcare, the medical field, and machine interfaces. These devices keep track individuals' biological and behavioral data to help with health communication and are often used for injury prevention. Those with hearing loss or impaired vision find it more difficult to recognize an approaching person or object; these sensing devices are particularly useful for such individuals, as they assist them with injury prevention by alerting them to the presence of people or objects in their immediate vicinity. Despite these obvious preventive benefits to developing Internet of Things based devices for the disabled, the development of these devices has been sluggish thus far. In particular, when compared with people without disabilities, people with hearing impairment have a much higher probability of averting danger when they are able to notice it in advance. However, research and development remain severely underfunded. In this study, we incorporated a wearable detection system, which uses an infrared proximity sensor, into a backpack. This system helps its users recognize when someone is approaching from behind through visual and tactile notification, even if they have difficulty hearing or seeing the objects in their surroundings. Furthermore, this backpack could help prevent accidents for all users, particularly those with visual or hearing impairments.

• Clinical Pain
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• v.19 no.2
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• pp.116-119
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• 2020

Cervical transforaminal epidural steroid injection (TFESI) is commonly performed to provide relief of pain caused by radiculopathy. Intra-arterial injection of particulate steroid or direct needle injury can lead to spinal artery embolism or thrombosis. Also there is a possibility of vascular spasm. To our knowledge, this is the first reported case of spinal cord infarction that occurred after TFESI with non-particulate steroid in Korea. A 47-year-old female patient underwent C7 TFESI at local pain clinic. Injected materials were dexamethasone and mepivacaine. Right after the intervention, she felt muscle weakness and decreased sensation. On physical examination, she had decreased sensation from C4 to T2 dermatome in light touch and pin-prick test. Proprioception and vibration were intact. The motor grades of upper extremities were grade 1. Cervical and thoracic spine MRI was checked. Diffusion-weighted image and apparent diffusion coefficient image showed long extension of spinal cord infarction from C2 to T1 level.

• The Journal of the Acoustical Society of Korea
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• v.42 no.1
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• pp.1-6
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• 2023

Sound radiated from a structure in vibration is an important physical characteristic to evaluate vibro-acoustic problem. Although sound radiation power can be typically obtained by intensity measurement, long measuring time and strict measuring condition remain difficult. As an alternative method, simulation-based estimation can be taken into account and its accuracy is known to be acceptable. However, difficulty still lies in that specialized softwares may be necessary to obtain sound radiation power and radiation efficiency. In this context, this study suggests two methods using an ordinary FE method to calculate sound radiation power. They are well-known reciprocity technique and p-p method, which are basically test methods. It is shown that either method can practically estimate sound radiation in the frame of conventional Finite Element Method (FEM). The methods and their corresponding limit are discussed with some results.

• Journal of the Korean Society of Safety
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• v.38 no.3
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• pp.27-34
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• 2023

With the technological development of the semiconductor industry, the roles of electrical and thermal energy supply and control of semiconductor equipment in ultrafine processes have become very important. However, instances of electrical fires in the chiller heater, which is used for cooling in the semiconductor manufacturing process, are increasing. A fire occurs in combustibles due to high heat at the connection part of the chiller heater, that is, when the number of electrical wires in the connection part is reduced or when the wires are completely disconnected. In this study, the temperature characteristics were compared and analyzed through experiments and 3D simulations. The number of electrical wires, which is the connection part of the chiller heater, was reduced by 90%, 50%, 30%, 10%, and 5%, and the wires were completely disconnected. When the number of electrical wires was reduced by 5%, heat of up to 80℃ was generated, which is a relatively high temperature but insufficient to cause a fire in combustibles. Complete disconnection occurred due to the vibration of the motor and other components, and sparks and arcs were generated, resulting in a rapid increase in temperature to up to 680℃. When completely disconnected, the temperature increase was sufficient to cause a fire in the combustibles covering the terminal block. Therefore, in this study, the causes of electrical fires in chiller heaters were investigated and preventive measures were proposed by analyzing abnormal signals and thermal characteristics caused by the electrical wiring being reduced and completely disconnected.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.755-760
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• 2016

The demand for independent generators using renewable energy has been increasing. Among those independent generators, small wind turbine generators have been actively developed. Permanent magnets are generally used for small wind turbine generators to realize a simple structure and small volume. On the other hand, cogging torque is included due to the structure of the permanent magnet synchronous machine, which can be the source of noise and vibration. The cogging torque can be varied by the shape of the permanent magnet and core, and it can be reduced using the appropriate design techniques. This paper proposes a design technique that can reduce the cogging torque by changing the shape of the permanent magnets for SPMSM (Surface Permanent Magnet Synchronous Motor), which is used widely for small wind turbine generators. Evolution Strategy, which is one of non-deterministic optimization techniques, was adopted to find the optimal shape of the permanent magnets that can reduce the cogging torque. The angle and outer diameter of permanent magnet were set as the design variable. A 300W class wind turbine generator, whose pole/slot combination was 8 poles/18 slots, was designed with the proposed design technique. The properties of the generator, including the cogging torque and output voltage, were calculated. The calculation results showed that the cogging torque of the optimized model was reduced compared to that of the initial model. The design technique proposed by this paper can be an effective measure to reduce the cogging torque.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.2
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• pp.147-156
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• 2017

The white cane, walking assistive device of visually impaired person, has disadvantages for acquiring the information by contacting obstacles directly and detecting low obstacle on the ground. Recently, new devices have been developing to solve these problems, but these were not widely used due to high price and appearance. Therefore, in this study, we developed two types of walking assistive shoes which were manufactured with infrared sensors, pressure sensors and vibrating motors. Two types of shoes were classified with single sensor (SS) and double sensor (DS) type according to the number of infrared sensor. To evaluate the effectiveness, we compared required time and number of collisions during walking with walking assistive shoes and white cane on obstacle area. As the results, required time was increased than white cane while number of collisions was decreased when walking with developed walking assistive shoes. In addition, required time and number of collisions was more reduced when using walking assistive device than white cane. Therefore, we suggests that developed walking assistive shoes can a great help to provide safe walking condition and reducing time to adapt new types of walking assistive shoes.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.10
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• pp.473-478
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• 2017

Drones require altitude holding in order to achieve flight objectives. The altitude holding of the drone is to repeat the operation of raising or lowering the drone according to the altitude information being measured in real-time. When the drones are maintained altitude, the drone's altitude will continue to change due to external factors such as imbalance in thrust due to difference in motor speed or wind. Therefore, in order to maintain the altitude of drone, we have to exactly measure the continuously changing altitude of the drone. Generally, the acceleration sensor is used for measuring the height of the drones. In this method, there is a problem that the measured value due to the integration error accumulates, and the drone's vibration is recognized by the altitude change. To solve the difficulty of the altitude measurement, commercial drones and existing studies are used for altitude measurement together with acceleration sensors by adding other sensors. However, most of the additional sensors have a limitation on the measurement distance and when the sensors are used together, the calculation processing of the sensor values increases and the altitude measurement speed is delayed. Therefore, it is necessary to accurately measure the altitude of the drone without considering additional sensors or devices. In this paper, we propose a measurement algorithm that improves general altitude measurement method using acceleration sensor and show that accuracy of altitude holding and altitude measurement is improved as a result of applying this algorithm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.10
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• pp.738-746
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• 2019

Instead of hydraulic actuation systems, an electromechanical actuation system is more efficient in terms of weight, cost, and test evaluation in the thrust vector control of the 7-ton gimbal engine used in the Korea Space Launch Vehicle-II(KSLV-II) $3^{rd}$ stage. The electromechanical actuator is a kind of servo actuator with position feedback and uses a BLDC motor that can operate at high vacuum. In the case of the gimballed rocket engine, a synthetic resonance phenomenon may occur due to a combination of a vibration mode of the actuator itself, a bending mode of the launcher structure, and an inertial load of the gimbals engine. When the synthetic resonance occurs, the control of the rocket attitude becomes unstable. Therefore, the requirements for the stiffness have been applied in consideration of the gimbal engine characteristics, the support structure, and the actuating system. For the 7-ton gimbal engine of the KSLV-II $3^{rd}$ stage, the stiffness requirement of the actuation system is $3.94{\times}10^7N/m$, and the direct drive type electromechanical actuator is designed to satisfy this requirement. In this paper, an equivalent stiffness analysis model of a direct drive electromechanical actuator designed based on the stiffness requirements is proposed and verified by experimental results.

• Journal of the Korea Computer Graphics Society
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• v.30 no.3
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• pp.171-178
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• 2024

Exercises using a Balance Board (BB) are effective in developing balance, strengthening core muscles, and improving physical fitness and concentration. In particular, the Smart Balance Board (SBB), which integrates with various digital content, provides appropriate feedback compared to traditional balance boards, maximizing the effectiveness of the exercise. However, most systems only offer visual and auditory feedback, failing to evaluate the impact on user engagement, interest, and the accuracy of exercise postures. This study proposes an Immersive Smart Balance Board (I-SBB) that utilizes multiple sensors to enable training with various feedback mechanisms and precise postures. The proposed system, based on Arduino, consists of a gyro sensor for measuring the board's posture, a communication module for wired/wireless communication, an infrared sensor to guide the user's foot placement, and a vibration motor for tactile feedback. The board's posture measurements are smoothly corrected using a Kalman Filter, and the multi-sensor data is processed in real-time using FreeRTOS. The proposed I-SBB is shown to be effective in enhancing user concentration and engagement, as well as generating interest, by integrating with diverse content.