• 한국정밀공학회지
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• 제32권1호
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• pp.9-16
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• 2015

The machining-chatter stands for a sudden relative vibration appeared between a material and a tool while processing with a machine. This chatter is key factor that seriously affects the quality of processed materials as well as being a factor which causes serious damages to the tool and the machine. This study is related to the monitoring and smart control of chatter problem that can compensate machining-chatter faster and produce processed goods with more precision by autonomous compensation. The above-mentioned machining-chatter compensator includes the chatter vibration sensor and the chatter compensator that estimates the compensation value according to the sensor detecting the chatter vibration of machine-tool and the chatter vibration detected from the sensor while having a feature of being organized by interlocking with the machine-tool controller.

• 한국응용과학기술학회지
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• 제38권4호
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• pp.951-962
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• 2021

본 연구는 만 40-60세 비만 중년여성을 대상으로 10주간 스마트머신 순환운동이 체조성, 폐기능, 혈중지질 및 인슐린 저항성에 미치는 영향을 구명하기 위하여 운동군(n=8), 대조군(n=6)으로 구분하여 실시하였다. 스마트머신 순환운동은 주 3회, 회당 55분으로 유산소 운동의 강도는 스마트머신과 POLAR T31이 연동 되어 스마트머신에 적용되며, 1-4주차는 40-50%HRR, 5-8주차는 50-60%HRR, 9-10주차는 60-70%HRR을 적용하였고, 저항성 운동의 강도는 스마트머신을 이용하여 등속성 운동 기반으로 대상자들의 1-RM test의 데이터 값을 이용하여 1-4주차는 1-RM의 40%, 5-8주차는 1-RM의 60%, 9-10주차는 1-RM의 80%를 적용하여 실시하였다. 그 결과 체중, 체질량지수, 체지방율, 허리-엉덩이둘레비율에서 그룹×시기 간 상호작용 효과가 나타났다. 폐기능의 FVC는 시기 간 주 효과와 사후 그룹 간 유의한 차이가 나타났으며, FVC 및 FEV₁은 그룹×시기 간 상호작용 효과가 나타났다. TC 및 TG는 시기 간 주 효과가 나타났으며, TC, TG 및 HDL-C는 그룹×시기 간 상호작용 효과가 나타났다. Insulin, Glucose 및 HOMA-IR은 운동 전·후 시기 간 차이에서 운동군이 유의하게 감소한 것으로 나타났다. 따라서 10주간 스마트머신 순환운동 프로그램이 비만 중년여성의 체조성, 폐기능, 혈중지질 및 인슐린 저항성에 긍정적인 영향을 미쳤으며 이는 중년여성의 비만을 개선하거나 비만을 예방할 수 있는 운동 프로그램이라고 사료된다.

• Smart Structures and Systems
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• 제30권3호
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• pp.255-261
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• 2022

When no extensometer is available in a generic tensile-compression test carried out by a universal testing machine (for instance the model BIONIX from Material Testing Systems (MTS)), the test results only provide the relative displacement between the machine grips. The test does not provide any information on the local behaviour of the material. This contribution presents the potential of an application of Digital Image Correlation (DIC) toward the reconstruction of the behaviour along the specimen. In particular, the authors test a Ni-Ti shape memory alloys (SMA) specimen with emphasis on the coupling of the two measurement techniques.

• 디지털산업정보학회논문지
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• 제13권4호
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• pp.81-90
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• 2017

This paper presents a smart seat for correction of driver posture while driving. We introduce good postures with seat height, seat angle, head height, back of knees, distances of foot pedals, tilt of seat, etc. There have been some studies on correction of good posture while driving, effects of driving environment on driver's posture, sitting strategies based on seating pressure distribution, estimation of driver's standard postures, and others. However, there are a few studies on guide of good postures while driving for problem of driver's posture using machine leaning. Therefore, we suggest a smart seat for correction of driver's posture based on machine leaning, 1) developed the system to get postures by 10 piezoelectric effect element, 2) collect piezoelectric values from 37 drivers and 28 types of cars, 3) suggest 4 types of good postures while driving, 4) analyze test postures by kNN. As the results, we can guide good postures for bad or problems of postures while driving.

• 드라이브 ㆍ 컨트롤
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• 제17권3호
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• pp.1-8
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• 2020

Recently, a special purpose machine with two manipulators and quadruped crawler system has been developed for rapid life-saving and initial restoration work at disaster sites. This special purpose machine provides the driver with various environmental recognition functions for accurate and rapid task determination. In particular, the human detection technology assists the driver in poor working conditions such as low-light, dust, water vapor, fog, rain, etc. to prevent secondary human accidents when moving and working. In this study, a human detection module is developed to be mounted on a special purpose machine. A thermal sensor and CCD camera were used to detect victims and nearby workers in response to the difficult environmental conditions present at disaster sites. The performance of various AI-based life detection algorithm were verified and then applied to the task of detecting various objects with different postures and exposure conditions. In addition, image visibility improvement technology was applied to further improve the accuracy of human detection.

• 드라이브 ㆍ 컨트롤
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• 제19권4호
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• pp.62-69
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• 2022

Construction machinery is exposed to accidents such as collisions, narrowness, and overturns during operation. In particular, mobile crane is operated only with the driver's vision and limited information of the assistant worker. Thus, there is a high risk of an accident. Recently, some collision avoidance device using sensors such as cameras and LiDAR have been applied. However, they are still insufficient to prevent collisions in the omnidirectional 3D space. In this study, a rotating LiDAR device was developed and applied to a 250-ton crane to obtain a full-space point cloud. An algorithm that could provide distance information and safety status to the driver was developed. Also, deep-learning segmentation algorithm was used to classify human-worker. The developed device could recognize obstacles within 100m of a 360-degree range. In the experiment, a safety distance was calculated with an error of 10.3cm at 30m to give the operator an accurate distance and collision alarm.

• 센서학회지
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• 제32권5호
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• pp.267-274
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• 2023

LiDAR, one of the most important sensing methods used in mobile robots and cars with assistive/autonomous driving functions, is used to locate surrounding obstacles or to build maps. For real-time path generation, the detection of potholes or puddles on the driving surface is crucial. To achieve this, we used the coordinates of the reflection points provided by LiDAR as well as the intensity information to classify water areas, which was achieved by applying a linear regression method to the intensity distribution. The rationale for using the LiDAR index as an input variable for linear regression is presented, and we demonstrated that it is not affected by errors in the distance measurement value. Because of LiDAR vertical scanning, if the reflective surface is not uniform, it is divided into different groups according to the intensity distribution, and a mathematical basis for this is presented. Through experiments in an outdoor driving area, we could distinguish between flat ground, potholes, and puddles, and kinematic analysis was performed to calculate the maximum width that could be crossed for a given vehicle body size and wheel radius.

• 드라이브 ㆍ 컨트롤
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• 제21권1호
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• pp.1-7
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• 2024

The locking performance of a multi-plate clutch with a mechanical lock-up system is governed by the engagement algorithm. In this paper, a control algorithm to improve the locking performance of the clutch was studied. A 1D dynamic model was constructed and simulated according to the developed algorithm. The developed algorithm was composed of a method in which the locking device is engaged while generating artificial slip on the friction plate by controlling the piston pressure of the clutch. Furthermore, a case study of the parameters within the developed algorithm was conducted to explore combinations that maximize locking performance and analyze trends according to these parameters.

• 한국IT서비스학회지
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• 제11권3호
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• pp.241-255
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• 2012

Recently, smart home environments which provide complex services through smart appliances are becoming realized, due to the advances in connected devices and network technologies. Current smart home environments are mostly restricted, because of difficultly of integration of heterogeneous smart appliances. Therefore radical service integration is impracticable. In this paper, we analyze and implement Machine-to-Machine (M2M) standards which are established by European Telecommunications Standards Institute (ETSI) for integrating heterogeneous devices and services. Smart Home is one of the areas covered by ETSI M2M standards, however these standards are just standardized, so adaption and assessment in smart home are not proved yet. Therefore, this paper analyze ETSI M2M standards by focusing the data transport model and evaluate by selecting the most commonly used smart home scenarios and by implementing ETSI M2M standards compatible smart metering system. In some points ETSI M2M standards are not efficient because of its complexity of structure, however ETSI M2M provides sophisticated features for integrating M2M which are appropriate to adopt diverse smart home environments.

• 한국전산구조공학회논문집
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• 제36권2호
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• pp.121-130
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• 2023

기어의 구조 안정성 및 치물림 성능을 분석하기 위하여 유한요소해석이 널리 사용된다. 본 연구에서는 스퍼 기어의 유한요소 모델링 조건이 해석 결과 및 간소화 효과에 미치는 영향을 분석하였다. 기어 구조 해석의 간소화 방법으로 기어 몸체 및 잇수 간소화, 요소망 생성 방식, 접촉 및 마찰 조건, 해석 조건 등을 선정하였다. 기어의 성능해석 지표로써 1주기의 기어 치물림 사이클 동안의 정전달 오차를 계산하였고, 간소화 지표로써 해석 소요 시간을 측정하였다. 유한요소해석을 통해 치물림 주기에 따른 접촉 응력 분포 및 변화 양상을 확인하였다. 모델링 조건에 따라 최대 전달 오차와 해석 소요 시간에 차이를 확인하고 원인을 분석하였다.