• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.1153-1154
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• 2006

This paper proposes the optimal design method based on NDZ analysis to secure the islanding defection ability and to maintain the stability and power quality when the grid is connected. A PSiM-based model and analysis of the system is presented, specialty aimed at improving the effectiveness of phase shift anti-islanding method with frequency feedback, which causes the inverter current to be generated slightly lower or higher in frequency than the frequency of the terminal voltage. The proposed method can cause frequency jump with leading and lagging phase of output current in two line cycles. As a result, the proposed algorithm is more sensitive and reliable than the conventional phase shift method. Experimental results, on a 3 kW inverter connected to 220 V, 60 Hz utility, are discussed.

• 한국멀티미디어학회논문지
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• 제24권10호
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• pp.1319-1325
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• 2021

It is important to remove fog for accurate object recognition and detection during preprocessing because images taken in foggy adverse weather suffer from poor quality of images due to scattering and absorption of light, resulting in poor performance of various vision-based applications. This paper proposes an end-to-end deep learning-based single image de-fogging method using U-Net architecture. The loss function used in the algorithm is a loss function based on Mahalanobis distance with fog features, which solves the problem of domain shifts, and demonstrates superior performance by comparing qualitative and quantitative numerical evaluations with conventional methods. We also design it to generate fog through the VGG19 loss function and use it as the next training dataset.

• 정신신체의학
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• 제25권2호
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• pp.166-175
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• 2017

연구목적 교대근무는 수면장애를 포함한 다양한 건강상의 문제와 연관이 있고 결국에는 삶의 질을 떨어뜨리는 것으로 알려져 있다. 그러나 임상현장에서는 주로 대상자의 주관적인 보고에 의하여 수면을 평가하고 있다. 본 연구는 정신과 교대근무 간호사의 수면을 주관적인 수면평가와 활동기록기를 이용한 수면평가를 통해 주간근무자와 비교해 보고자 하였다. 방 법 교대근무 간호사 23명과 주간근무 간호사 25명을 대상으로 하였다. PSQI를 이용하여 주관적인 수면의 질을 평가하였고 기타 자기보고척도를 이용하여 정신사회적 측면을 평가하였다. 객관적인 수면을 측정하기 위해 활동기록기를 총 7일간 착용하도록 하였고, 그 기간 동안 수면일지를 함께 작성하였다. 교대근무군과 주간근무군간에 활동기록기의 수면변수, PSQI 총점과 구성요소 그리고 자기보고척도로 평가한 결과를 비교하였다. 결 과 PSQI 총점은 양군 간 유의한 차이를 보이지는 않았으나 PSQI 구성요소 중에서 교대근무군이 유의하게 수면의 질(C1)이 나쁘고, 수면장애(C5)와 수면제 사용(C6)이 많으며, 주간기능장애(C7)가 심한 것으로 나타났다. 활동기록기로 측정한 수면변수에서 교대근무군이 주간근무군에 비해 유의하게 잠자리에 누워있는 시간과 총 수면시간이 짧으며, 수면효율이 떨어지고, 평균각성시간이 긴 것으로 나타났다. 결 론 교대근무 간호사가 주간근무 간호사에 비해 주관적 수면평가 및 활동기록기를 통한 객관적 지표 모두에서 수면에 문제를 보이는 것으로 나타났다. 본 연구는 활동기록기가 수면장애를 평가하는데 있어 주관적 설문만으로는 측정이 어려운 객관적 수면변수를 측정하는 데 유용한 도구일 가능성을 시사한다.

• 동서간호학연구지
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• 제17권2호
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• pp.117-124
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• 2011

Purpose: This study was done to compare organizational commitment, job satisfaction and job stress according to nurses' adult attachment styles. Methods: Data were collected by self-report questionnaires measuring Adult attachment style, Organizational commitment, Job satisfaction and Job stress from a convenience sample of 253 shift nurses in a hospital. Results: There were security style (31.2%), dismissing-avoidance (18.6%), preoccupation (17.8%) and fearful-avoidance (32.4%) among 4 attachment styles in these shift nurses. Their organizational commitment level (M=3.2), job satisfaction (M=2.7) and job stress (M=3.3) were revealed. Subjects who were in security attachment style showed significantly higher scores of organizational commitment (F=5.09, p=.002) and job satisfaction (F=13.02, p<.001) than subjects in fearful-avoidance attachment style. Meanwhile, this study showed that subjects who were in fearful-avoidance attachment style recorded significantly higher scores of job stress than subjects in any other attachment style (F=3.15, p=.026). Conclusion: This study demonstrated a relevant difference in organizational commitment, job satisfaction and job stress in accordance with the attachment style of shift nurses. These results indicate the need for attachment promotion program for shift nurses. And nurses' attachment styles should be considered in future interventions to enhance quality of nursing care.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.723-729
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• 2001

Electro-hydraulic shift control of a vehicle automatic transmission has been predominantly carried out via an open-loop control based on numerous time-consuming calibrations. Despite remarkable success in practice, the variations of system characteristics inevitably deteriorate the performance of the tuned open-loop controller. As a result, the controller parameters need to be continuously updated in order to maintain satisfactory shift quality. This paper presents a self-learning algorithm for automatic transmission shift control in a construction vehicle during inertia phase. First, an observer reconstructs the turbine acceleration signal (impossible to measure in a construction vehicle) from the readily accessible turbine speed measurement. Then, a control algorithm based on a quadratic function of the turbine acceleration is shown to guarantee the asymptotic convergence (within a specified target bound) of the error between the actual and the desired turbine accelerations. A Lyapunov argument plays a crucial role in deriving adaptive laws for control parameters. The simulation and hardware-in-the-loop simulation (HILS) studies show that the proposed algorithm actually delivers the promise of satisfactory performance despite the system characteristics variations and uncertainties.

• 드라이브 ㆍ 컨트롤
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• 제14권4호
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• pp.29-36
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• 2017

Electronic control technologies that have long been developed for passenger cars spread to construction equipment and agricultural vehicles because of its outstanding performance achieved by embedded software. Especially, system program of transmission control unit (TCU) plays a crucial role for the superb shift quality, driving performance and fuel efficiency, etc. Since the control algorithm is embedded in software that is rarely analyzed, development of such a TCU cannot be conducted by conventional reverse engineering. Transmission simulator is a kind of electronic device that simulates the electric signals including driver operation command and output of various sensors installed in transmission. Standalone TCU can be run in normal operation mode with the signals provided by transmission simulator. In this research, transmission simulator for the tracked vehicle TCU is developed for the analysis of shift control algorithm from the experiments with standalone TCU. It was confirmed that shift experimental data for the simulator setup conditions can be used for the analysis of control algorithms on proportional solenoid valves and shift map.

• 드라이브 ㆍ 컨트롤
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• 제18권2호
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• pp.46-55
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• 2021

A forklift is a powered industrial vehicle used to lift and move materials over short distances. Nowadays, almost all forklifts are equipped with an automatic transmission due to its improved operator comfort and increased productivity. Thanks to marked improvement of transmission control unit equipped with highly-advanced microcontrollers, recently developed automatic transmission for forklift have various auxiliary functions such as creep, auto retardation, and automatic shift with excellent shift quality. This paper deals with the creep function which enables one to maneuver a forklift at the designated low speed by slip control of clutches. The design of creep function was based on four modes of creep operation depending on the status of the operator's shift lever and accelerator pedal. Control algorithms and control parameters for each mode were designed to achieve the desired static and dynamic performance. Vehicle test for the designed creep function was carried out with an independently developed embedded controller. Test results confirmed good creep speed control without speed error at a steady state with a mild shift shock during mode changes by stepping or releasing the accelerator.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권6호
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• pp.176-185
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• 2021

This paper aims to develop a new paradigm for groundwater management which is compatible with integrated water management policies in Korea. Three key roles of groundwater are defined for addressing water cycle distortion, high water stress, water quality degradation, aquatic ecosystems deterioration, and water-related hazards. Firstly, groundwater plays an important role in contributing soundness of water cycle as a component of water cycle. Secondly, it is a local water resource to ensure water supply sustainability. Thirdly, groundwater is an essential water resource for drought and emergencies. In order to support the groundwater roles, we propose a paradigm shift for groundwater management and policy directions towards integrated water management. The new paradigm consists of managements for sound water cycle on a watershed scale and groundwater environment(quantity, quality, and groundwater dependent ecosystems) managements for both human and nature. A prospective management also constitutes the new paradigm. In addition, this paper proposes four policy directions in groundwater management. The policies emphasize the integrated management of groundwater and surface water, management of groundwater environment(quantity, quality, and groundwater dependent ecosystems), management of groundwater uses for water sustainability and security, and enhancement of groundwater publicity.

• 품질경영학회지
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• 제47권1호
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• pp.87-96
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• 2019

Purpose: The purpose of this paper is to determine an optimal production time for economic production quantity model with preventive maintenance and random defective rate as the function of a machinery deteriorates. Methods: If a machinery shifts from "in-control" state to "out-of-control" state, a proportion of defective items being produced increases. It is assumed that time to state shift is a random variable and follows an arbitrary distribution. The elapsed time until process shift decreases stochastically as a production cycle repeats and quasi-renewal process is used to implement for production facilities to deteriorate. Results: When the exponential parameter for exponential distribution increases, the optimal production time increases. When Weibull distribution is considered, the optimal production time is closely affected by the shape parameter of Weibull distribution. Conclusion: A mathematical model is suggested to find optimal production time and optimal number of production cycles and numerical examples are implemented to validate the patterns for changes of optimal times under different parameters assumptions. The real application is implemented using the proposed approach.

• 한국콘텐츠학회논문지
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• 제6권9호
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• pp.19-27
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• 2006

Mean shift 방법은 중심 모드를 찾기 위한 비모수적 통계 방법으로 컬러 영상을 분할하는데 효율적이다. 그러나 입력되는 윈도우 크기에 따라 분할된 결과가 달라지며 윈도우의 크기 값이 작을 경우 많은 영역으로 분할되는 단점이 있다. 본 논문은 이러한 단점을 개선하여 mean shift 알고리즘에 의한 분할 영상이 과도하게 분할되었을 경우 영역 병합 방법을 이용하여 유사 영역을 병합하는 방법을 제안한다. 제안 방법은 과분할된 영상을 HSI 컬러 공간으로 변환하여 색상 정보를 이용하여 유사 영역으로 병합하며 이때 경계 영역을 보존하기 위해 영역 병합 제한자를 이용하여 병합 유무를 결정한다. 그 후 RGB 컬러 공간을 이용하여 HSI 컬러 공간에서 병합되지 않은 영역들을 병합하였다. 실험 결과는 다양한 영상에 대해 주요 영역들의 분할 결과에서 우수한 성능을 보여준다.