• 대한의용생체공학회:의공학회지
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• 제44권3호
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• pp.182-189
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• 2023

CT is a medical device that acquires medical images based on Attenuation coefficient of human organs related to X-rays. In addition, using this theory, it can acquire sagittal and coronal planes and 3D images of the human body. Then, CT is essential device for universal diagnostic test. But Exposure of CT scan is so high that it is regulated and managed with special medical equipment. As the special medical equipment, CT must implement quality control. In detail of quality control, Spatial resolution of existing phantom imaging tests, Contrast resolution and clinical image evaluation are qualitative tests. These tests are not objective, so the reliability of the CT undermine trust. Therefore, by applying an artificial intelligence classification model, we wanted to confirm the possibility of quantitative evaluation of the qualitative evaluation part of the phantom test. We used intelligence classification models (VGG19, DenseNet201, EfficientNet B2, inception_resnet_v2, ResNet50V2, and Xception). And the fine-tuning process used for learning was additionally performed. As a result, in all classification models, the accuracy of spatial resolution was 0.9562 or higher, the precision was 0.9535, the recall was 1, the loss value was 0.1774, and the learning time was from a maximum of 14 minutes to a minimum of 8 minutes and 10 seconds. Through the experimental results, it was concluded that the artificial intelligence model can be applied to CT implements quality control in spatial resolution and contrast resolution.

• 디지털산업정보학회논문지
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• 제15권2호
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• pp.43-52
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• 2019

The recent technological developments of smart devices, multiple services are provided to enhance the users' quality of life including smart city, smart energy, smart car, smart healthcare, smart home, and so on. Academia and industries try to provide the users with convenient services upon seamless technological research and developments. Also, whenever and wherever a variety of services can be used without any limitation on the place and time upon connecting with different types of devices. However, security weaknesses due to integrations of multiple technological elements have been detected resulting in the leakage of user information, account hacking, and privacy leakage, threats to people's lives by device operation have been raised. In this paper, safer communication framework is suggested by device control and user authentication in the mobile network environment. After implementations of registration and authentication processes by users and devices, safe communication protocol is designed based on this. Also, renewal process is designed according to the safe control of the device. In the performance evaluation, safety was analyzed on the attack of protocol change weakness occurred in the existing system, service halt, data leakage, illegal operation control of message, and so on, which confirmed the enhanced speed approximately by 8% and 23% in the communication and verification parts, respectively, compared to the existing system.

• 한국IT서비스학회지
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• 제11권1호
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• pp.239-246
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• 2012

The user increases around the WiBro and in which the mobile broad band service is the wireless internet base technology HSDPA, that is the cellular phone foundation technique, and moreover the issue about the user effective quality guarantee emerges but the quality control of the wireless network is the incomplete actual condition. Therefore, the reliability verification according to the development of the system for the performance measure for the continued wireless data service and it and evaluation are needed for the quality control. In this paper, the wireless data service quality measurement system was implemented with the design. The same test environment as the existing network performance measurement program was built for the reliability verification of the embodied device for measuring quality and evaluation and the cost performance was performed. It could confirm that design and embodied wireless data service quality measurement system operated accurately in this paper through the quality measure result value analysis.

• Journal of Power Electronics
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• 제15권4호
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• pp.1054-1065
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• 2015

Multi-functional voltage source inverters (VSIs) have attracted increasing attention in recent years for their advantageous auxiliary services for power quality enhancement in autonomous microgrids. These types of VSIs can not only achieve a proper control scheme in autonomous mode but also cope with the prescribed power quality and stability requirements. These functionalities are integrated within the same device, thereby significantly improving the cost-effectiveness of microgrids while decreasing the investment and bulk compared with those of multiple devices with independent functionalities. Control strategies for power quality enhancement in autonomous microgrids using multi-functional VSIs are comprehensively reviewed in this paper. In addition, such VSIs are discussed in detail, and comparisons of which are also provided. Lastly, a number of future research directions for multi-functional VSIs are recommended.

• 한국응급구조학회지
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• 제18권1호
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• pp.107-116
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• 2014

Purpose : The purpose of this study is to demonstrate the effectiveness of using a digital sensor device during CPR by analyzing the results from that chest compressions with a digital sensor device are applied to cardiac arrest patients. Methods : This study analyzed the results from the experiment that 42 people were selected randomly among Korean 119 rescuers, and they divided into the experimental group using a digital sensor device and the control group only using their hands, then they had been observed to conduct chest-compressions to mannequins for 10 minutes. Results : The results were found that compression depth in both the control and experimental group was gradually decreased over time, but the experimental group not only kept the depth but also maintained the speed of chest-compressions close to 100 times a minute. In addition, due to the use of the digital sensor device, the insufficient recoil ratio of chest-compressions was significantly reduced. Conclusion : The results show that conducting chest-compressions with a digital sensor device keeps the compression-death, maintains the speed of chest-compression properly and makes the insufficient relaxation ratio of chest-compressions reduce significantly.

• 전기전자학회논문지
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• 제25권3호
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• pp.462-466
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• 2021

DVR은 배전선로의 전압 변동을 보상하는 장치로 일반적으로 계통의 무효전력 보상, 역률개선 문제를 해결하는 장치와 결합하여 사용된다. 이러한 결합보상기기는 상대적으로 제어가 어렵고 부피가 커지는 단점을 갖는다. 본 논문에서는 DVR의 전력위상제어(Power Angle Contorl)방법을 적용하여 부가적인 보상기기의 결합이 없이 DVR 단독으로 배전선로의 무효전력과 전압변동을 동시에 보상하기 위해 보상 전압의 최대 크기와, 위상, 보상 가능한 무효전력 및 유효전력에 대한 수학적 해석을 수행하였다. 유효전력을 배터리에 충전하고 전압 변동시 저장된 에너지를 공급하기 위한 제어알고리즘을 개발하고 Matlab 시뮬레이션을 통해 결과를 확인하였다.

• 품질경영학회지
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• 제41권3호
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• pp.405-412
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• 2013

Purpose: In this paper, the improvement of the image quality is investigated. The image quality is degraded by the drift phenomenon of EO/IR (Electro-Optical/Infrared) device on UAV. The drift phenomenon means that the image of EO/IR equipment on UAV(Unmanned Aerial Vehicle) moves to the unintended direction. This phenomenon should be improved for successful flight mission. Methods: To improve the drift phenomenon, the drift compensation method, the combination algorithm of FMC(Forward Motion Compensation) and AMC(Angular Motion Compensation) method, are introduced to calculate pitch and azimuth angle. Result values of pitch and azimuth angle are used for the improvement of image quality in EO/IR control logic. Results: The image quality is quantitatively improved more than 15 times through field test data of flight. Conclusion: Using the drift compensation technique, the image quality for EO/IR equipment is improved over 15 times than existing methods. This means the user of UAV with EO/IR device can perform a successful mission by keeping the line of sight for the target accurately.

• 한국지반공학회논문집
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• 제38권11호
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• pp.97-106
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• 2022

국내 매입말뚝 시공방법은 선굴착 후 최종단계의 항타 관입량으로 관리하는 것이 일반적이다. 관입량은 오래전부터 수기 측정방식에 의해 이루어지고 있으며, 작업자의 안전문제와 측정값의 신뢰도 부족 등에도 작업성의 한계와 비용 문제로 자동화 기술이 적용되지 않고 있다. 본 연구에서는 비접촉식 말뚝 관입량 측정 장치를 개발하고 기존 장치와 비교계측을 통해 현장 성능을 검증하였다. 또한 관입량 측정장치를 활용하여 현장 품질관리 방법에 대해 분석하였다. 실제 현장 실험을 통해 개발 장치를 활용한 관입량 측정과 수정 Hiley공식 및 동적감쇠계수 산정을 통해 보다 신뢰도 높은 지지력 추정이 가능한 것을 확인하였다. 연구결과에 따라 각 현장마다 수행된 동재하시험으로 부터 현장 보정 절차가 이루어지면 보다 신뢰성 높은 지지력 추정이 가능하며, 실제 현장에서는 동재하시험이 수행되지 않은 말뚝에 대해서도 지지력 관점의 말뚝 시공관리에 활용할 수 있을 것으로 판단된다.

• International Journal of Control, Automation, and Systems
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• 제5권5호
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• pp.515-525
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• 2007

In this paper, we develop a co-design methodology of stochastic optimal controllers and network parameters that optimizes the overall quality of control (QoC) in networked control systems (NCSs). A new dynamic model for NCSs is provided. The relationship between the system stability and performance and the sampling frequency is investigated, and the analysis of co-design of control and network parameters is presented to determine the working range of the sampling frequency in an NCS. This optimal sampling frequency range is derived based on the system dynamics and the network characteristics such as data rate, time-delay upper bound, data-packet size, and device processing time. With the optimal sampling frequency, stochastic optimal controllers are designed to improve the overall QoC in an NCS. This co-design methodology is a useful rule of thumb to choose the network and control parameters for NCS implementation. The feasibility and effectiveness of this co-design methodology is verified experimentally by our NCS test bed, a ball magnetic-levitation (maglev) system.

• 한국의료질향상학회지
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• 제23권1호
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• pp.55-67
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• 2017

Purpose:The purpose of this study was to apply the disinfection method using chlorhexidine in practice on disinfection of vascular access for hemodialysis. Methods: This study was designed as a randomized controlled trial for examining effectiveness on infection of the vascular access device for hemodialysis when using chlorhexidine and betadine/alcohol. One-hundred-thirty study participants were separated into two groups randomly. Infection signs of the vascular access device for hemodialysis were observed and recorded before disinfection on vascular access device. Result: Before the study, there was no difference between the experimental group (chlorhexidine group) and the control group (betadine/alcohol group) in general characteristics and hematological index. Incidence of infection rate of chlorhexidine group was 0 percent and the betadine/alcohol group was 1.5 percent. There was no significant difference between the two groups. Conclusion: This study examined the effectiveness of prevention of infection with the disinfection method using chlorhexidine and betadine/alcohol. The disinfection method using chlorhexidine is considered an effective and alternative method of betadine/alcohol.