• Tribology and Lubricants
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• 제35권3호
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• pp.158-168
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• 2019

This paper presents the investigation of two types of rotordynamic modeling issues for 2.2 kW-class, rated speed of 1,800 rpm, squirrel-cage type induction motors. These issues include the lamination structure of rotor cores, and the radial clearance of ball bearings that support the shaft of the motor. Firstly, we focus on identifying the effects of rotor core lamination on the rotordynamic analysis via a 2D prediction model. The influence of lamination is considered as the change in the elastic modulus of the rotor core, which is determined by a modification factor ranging from 0 to 1.0. The analysis results show that the unbalanced response of the rotor-bearing system significantly varies depending on the value of the modification factor. Through modal testing of the system, the modification factor of 0.079 is proven to be appropriate to consider the effects of lamination. Next, we investigate the influence of ball bearing clearance on the rotordynamic analysis by establishing a bearing analysis model based on Hertz's contact theory. The analysis results indicate that negative clearance greatly changes the bearing static behavior. Rotordynamic analysis using predicted bearing stiffness with various clearances from -0.005 mm to 0.010 mm reveals that variations in clearance result in a slight difference in the displacement of the system up to 18.18. Thus, considering lamination in rotordynamic analysis is necessary as it can cause serious analysis errors in unbalanced response. However, considering the effect of the bearing clearance is optional because of its relatively weak impact.

• 실천공학교육논문지
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• 제9권1호
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• pp.7-13
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• 2017

종합 설계 교과를 이수하고 성과 결과물로 졸업 조건 만족하기 위한 작품제작이 연결되는 전공중심의 학습활동을 통해 공학교육의 실천 방안을 제시한다. 설계 구성된 주제는 초음파 센서의 장애물 감지 기능을 이용하여 주행 도중 최소 안전거리를 측정하고, 가속도 자이로 센서의 측정값을 기반으로 회피 알고리즘을 수행하는 것으로 한다. 드론과 주변 사물, 사람의 피해를 최소화하며 공중 이동 성능을 향상 시키는 접근 감시 시스템을 제안한다. 실험 결과 5개의 초음파센서를 통해 드론 주변의 장애물을 감지하며, 드론 각각의 모터에 출력값의 차이가 적용되고, 장애물 회피를 확인하였다. 또한 공학교육인증 프로그램의 학습성과 성취도 측정을 위한 자료의 내용과 수준으로 과정에서 얻어진 결과를 사용하였고, 4년제 공과대학 졸업예정자에게 요구되는 공학문제수준설명에 부합함을 확인하였다.

• PNF and Movement
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• 제17권1호
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• pp.119-127
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• 2019

Purpose: The purpose of this study is to show the effect of elastic band on balance and functional ability in chronic stroke patients living in community. Methods: The subjects who participated in the study were 9 patients with chronic stroke. One of them gave up during the study, finally 8 patients performed. The intervention was conducted once a week for 10 weeks. In this study functional reach test (FRT), timed up and go test (TUG), Tinetti performance oriented mobility assessment (Tinetti-POMA) were measured for balance. The coordination training of arms and legs using the elastic band was performed in three positions as supine, side lying, sitting. One arm performed flexion-adduction- external rotation with elbow flexion pattern and the opposite side(diagonal) leg was performed flexion-adduction-external rotation with knee flexion pattern, the other arm's pattern was extension-abduction-internal rotation with elbow extension and the opposite side (diagonal) leg was in extension-abduction-internal rotation with knee extension pattern. The training was performed in each position for 15 minutes in per position. The participants had a five minute break after each training. Results: The results are as follows. FRT and Tinetti-POMA showed significant increase statistically in each position. The TUG showed significant decrease statistically in each position. Conclusion: Even though the coordination training with elastic band had performed once a week, it showed positive effects on balance in chronic stroke patients. Therefore, if we can suggest the appropriate frequencies of coordination training of arms and legs using the elastic band, it can be a method to improve daily life and life quality to patients with chronic stroke.

• 융합정보논문지
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• 제11권2호
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• pp.229-237
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• 2021

노인과 경증 뇌질환(치매 및 뇌졸중 등) 환자들 중 일정 정도의 자력 행동 능력과 인지 능력이 있는 경우에는 운동과 인지 재활을 병행해야만 하는 경우가 많다. 그러나 기존의 재활 시스템은 대부분 운동 또는 인지 재활로 분리 또는 특화 되어 있는 경우가 많아서 두 가지 모두를 연계하는 형태에 대한 필요성이 있다고 생각된다. 본 논문에서는 ICT 기술의 하나인 CAN 통신 프로토콜을 이용하여 운동과 인지 재활을 병행할 수 있도록 하는 게임형 재활시스템을 제안하고자 한다. 이 시스템은 CAN BUS 구조를 이용하여 재활 시스템을 구성하는 각각의 개별 모듈들을 다양한 형태로 분리 및 결합 사용이 가능하도록 한다. 환자(또는 노인)의 인지 능력과 운동 능력의 정도에 따라 다양한 형태의 재활 환경을 구현할 수 있음을 보이고자 제안된 시스템의 프로토 타입을 실제로 제작하였다. 아울러 이 시스템을 이용한 몇 가지 실험을 통하여 여러 환경에 적용 가능한 운동/인지 병행 재활의 구현 가능성을 보이고 있다.

• Journal of Dental Anesthesia and Pain Medicine
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• 제20권6호
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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.

• 한국정보통신학회논문지
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• 제25권1호
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• pp.36-43
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• 2021

본 논문에서는 제조 공장 내 AGV (Automated Guided Vehicle) 주행 중 객체 인식을 위한 YOLO v3 알고리즘의 정확도에 대해 살펴보았다. 실험을 위해 2D LiDAR 및 스테레오 카메라가 장착된 AGV를 준비하였다. AGV 주행 중 2D LiDAR를 활용한 SLAM 기법으로 지도 정보를 획득하였고 스테레오 카메라를 활용한 객체 인식이 이루어졌다. 그리고 YOLO v3 알고리즘 기반의 학습 정도에 따른 재현율, AP, mAP 등을 측정하였다. 실험 결과, 4000장의 train data 와 500장의 test data 로 훈련된 YOLO v3 알고리즘에 AGV에 장착된 스테레오 카메라의 시점과 높이에서 획득한 1200장의 이미지를 추가로 학습할 경우 mAP가 약 10% 향상되었다. 정밀도(precision) 와 재현율 역시 각각 6.8%와 16.4% 향상되었다.

• 한국정보통신학회논문지
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• 제24권4호
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• pp.459-466
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• 2020

멀티로터 UAV(Unmanned Aerial Vehicle)를 이용해서 수집한 음향 데이터는 모터나 프로펠러에서 발생하는 자체 소음이나 비행 중 발생하는 바람 소리 등으로 인해 음향 품질이 크게 손상되는 문제가 발생한다. 멀티로터 UAV 환경에서는 목표 음향의 크기뿐만 아니라 위상도 크게 손상되기 때문에 크기와 위상을 모두 고려해서 음향을 향상시킬 필요가 있다. 하지만 위상은 크기와 달리 구조적인 특징이 잘 나타나지 않으므로 향상시키는 것이 쉽지 않다. 따라서 본 연구에서는 크기와 위상을 모두 표현할 수 있는 복소 스펙트로그램을 기초로 잡음을 제거해서 목표 음향의 품질을 향상시키는 CNN 기반 복소 스펙트로그램 향상 방법을 제안한다.

• Biomolecules & Therapeutics
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• 제30권4호
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• pp.320-327
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• 2022

Neurodevelopmental disorders are complex conditions that pose difficulty in the modulation of proper motor, sensory and cognitive function due to dysregulated neuronal development. Previous studies have reported that an imbalance in the excitation/inhibition (E/I) in the brain regulated by glutamatergic and/or GABAergic neurotransmission can cause neurodevelopmental and neuropsychiatric behavioral deficits such as autism spectrum disorder (ASD). NMDA acts as an agonist at the NMDA receptor and imitates the action of the glutamate on that receptor. NMDA however, unlike glutamate, only binds to and regulates the NMDA receptor subtypes and not the other glutamate receptors. This study seeks to determine whether NMDA administration in mice i.e., over-activation of the NMDA system would result in long-lasting behavioral deficits in the adolescent mice. Both gender mice were treated with NMDA or saline at early postnatal developmental period with significant synaptogenesis and synaptic maturation. On postnatal day 28, various behavioral experiments were conducted to assess and identify behavioral characteristics. NMDA-treated mice show social deficits, and repetitive behavior in both gender mice at adolescent periods. However, only the male mice but not female mice showed increased locomotor activity. This study implies that neonatal exposure to NMDA may illicit behavioral features similar to ASD. This study also confirms the validity of the E/I imbalance theory of ASD and that NMDA injection can be used as a pharmacologic model for ASD. Future studies may explore the mechanism behind the gender difference in locomotor activity as well as the human relevance and therapeutic significance of the present findings.

• International Journal of Computer Science & Network Security
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• 제22권3호
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• pp.37-44
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• 2022

Plug-in Hybrid electric vehicles (PHEV) show great potential to reduce gas emission, improve fuel efficiency and offer more driving range flexibility. Moreover, PHEV help to preserve the eco-system, climate changes and reduce the high demand for fossil fuels. To address this; some basic components and energy resources have been used, such as batteries and proton exchange membrane (PEM) fuel cells (FCs). However, the FC remains unsatisfactory in terms of power density and response. In light of the above, an electric storage system (ESS) seems to be a promising solution to resolve this issue, especially when it comes to the transient phase. In addition to the FC, a storage system made-up of an ultra-battery UB is proposed within this paper. The association of the FC and the UB lead to the so-called Fuel Cell Battery Electric Vehicle (FCBEV). The energy consumption model of a FCBEV has been built considering the power losses of the fuel cell, electric motor, the state of charge (SOC) of the battery, and brakes. To do so, the implementing a reinforcement-learning energy management strategy (EMS) has been carried out and the fuel cell efficiency has been optimized while minimizing the hydrogen fuel consummation per 100km. Within this paper the adopted approach over numerous driving cycles of the FCBEV has shown promising results.

• 대한물리의학회지
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• 제17권3호
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• pp.31-40
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• 2022

PURPOSE: This study was conducted to investigate the effects of postural control training using a visual blind board, on head control, trunk control, and the sitting abilities of children with moderate-to-severe cerebral palsy. METHODS: Ten children with moderate to severe cerebral palsy participated in this study. Postural control training with a visual blind board was given for 40 minutes per session, 3 times a week for 4 weeks (12 sessions). Before and after the intervention, head control, trunk control, and sitting abilities were quantified using the head control scale, Korean version-trunk control measurement scale, and the sitting part of the Korean version-gross motor function measure-88, respectively. RESULTS: Postural control with the visual blind board significantly improved the head control ability of children with moderate to severe cerebral palsy (p = .015). Their trunk control abilities also showed significant improvement after the intervention (p = .016). However, their sitting ability did not show a significant change. CONCLUSION: These results showed that postural control training using a visual blind board is effective in improving the head and trunk control abilities of children with cerebral palsy. Further studies with suitable sample sizes and control groups are needed to reach a conclusion about the use of postural control training with visual blind boards for improvement of postural control of children with moderate to severe cerebral palsy.