• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.364-372
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• 2016

In this paper, a voltage controller for the seamless transition of a grid-connected inverter for ESS is proposed. The single-phase inverter is operated as a current controller when the grid is connected and as a voltage controller in the stand-alone mode when the grid is disconnected. Generally, in the case of grid recovery, the overcurrent may flow into the system because of the mismatch phase between the inverter output and grid voltages. The proposed controller resolves the overcurrent problem through phase delay problems with initial value feed-forward control of the integrator when the grid voltage is restored. The effects of the control method are simulated through PSIM, and the usefulness of the control method is verified through experiments.

• Applied Microscopy
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• v.48 no.2
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• pp.43-48
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• 2018

Transition metal dichalcogenide (TMD) materials have distinctive structures in comparison with other two-dimensional materials. TMD materials' structure is held together by van der Waals and covalent intralayer interactions; consequently, TMDs exhibit multiple phases and properties depending on their structure. This article reviews some of the research currently being undertaken to control TMD phases to utilize their different properties. This review introduces some trials for changing the phase of TMDs.

• Journal of the Korean Home Economics Association
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• v.44 no.12
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• pp.53-64
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• 2006

The purpose of this study was to investigate the variables on employees' retirement expectations divided into imposed frustration, new beginning, transition to rest, and continuing. Independent variables were individual(gender, age, occupation, income, education, and health condition), psychological(self-esteem, locus of control, attitude of leisure, and attitude of family), and job-related variables(job attitude, job satisfaction, and job stability). In order to achieve this purpose, a survey was conducted with 515 employees from Daegu and Kyungpook. Retirement expectations were measured with questionnaire based on several studies. The data analyzed by frequency, percentage, mean, factor analysis, Cronbach's $\alpha$, correlation, and multiple regression. The major findings were as follows. First, imposed frustration was affected by income, self-esteem, locus of control, job satisfaction, job attitude, and job stability. Second, new beginning was affected by self-esteem, locus of control, attitude toward leisure and family, and job stability. Individual variables were not statistically significant predictors of new beginning. Third, transition to rest was affected by locus of control, attitude toward family, job satisfaction, job attitude, and job stability. Individual variables were not statistically significant predictors of transition to rest. Finally, continuing was affected by age, education, job satisfaction. Psychological variables were not statistically significant predictors of continuing.

• Journal of Digital Convergence
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• v.9 no.6
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• pp.153-163
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• 2011

This study analyzes the military and political factors that influenced the Participatory Government's resolution in Wartime Operational Control (OPCON) Transition. The research on key factors in OPCON transition firstly implemented literature research and then increased feasibility through additional use of AHP. The analysis results showed that there was a negative effect for Korean Peninsular Defense in the 'ROK-US Alliance Asymmetry' area, a positive effect to increase ROK-led Capability of Theater Operation in the 'ROK and U.S. Alliance Interdependence' area and a positive effect for Invocation of ROK Self-Defense Power in the 'Interests of Participatory Government's Liberal Regime' area respectively. After applying AHP, "ROK exercise of Self-defense" in the 'Interests of Participatory Government's Liberal Regime' area received the highest assessment, while the "Increasement of North Korea's Threat" in the 'ROK-US Alliance Asymmetry' area received the lowest assessment. This study is meaningful in that it analyzed the key military and political factors in the Participatory Government's resolution of Wartime OPCON Transition using AHP.

• Journal of Digital Convergence
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• v.12 no.7
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• pp.37-47
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• 2014

This study applies Policy Streams and Expert Group Standing Change Framework (PSECF) proposed by SangJung Park and Chan KOH to analyze the Roh's Participatory government's decision making process on the wartime Operational Control (OPCON) transition. PSECF case study's results are as follows: Strong commitments of the former president Roh Moohyun and the progressive National Security Committee (NSC) were primary drivers in the policy developing process. But military expert groups such as the Ministry of National Defense (MND) and the Joint Chiefs of Staffs (JCS) were thoroughly excluded due to their passive role against the wartime OPCON transition. After the policy resolution, the standing of expert groups changed: the standing of advocate effects, the former progressive NSC who led the wartime OPCON transition in the Roh's Participatory government, went down but the conservatives such as ROK MND and JCS improve their standing because the conservative government kicks off 8 months later from the policy decision. In conclusion, the proposed PSECF through the Roh's Participatory government's case-study is worthy as an explanatory framework for high level national policies.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2006-2009
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• 2005

This paper presents a method for registering images using phase correlation technique in fourier domain, hough transform and multi-resolution wavelet. To register images, source and input images are transformed to wavelet domain. An angular transition can be obtained by applying hough transform technique followed by phase correlation. Then we apply phase correlation technique to find x-axis and y-axis transition. We apply wavelet transform to reduce processing time and also use its coefficients as edge information instead of canny detector. With multi-resolution property of wavelet transform, registration time can be greatly reduced. After we get all transition parameters, we transform the input images according to these parameters. Then, we compose and blend all images into a new large image with details of all source images. From our experiment, we can find the accurate transition both x-y translation and angular transition with less error.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.29-36
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• 2024

Recently, the concept of Urban Air Mobility (UAM) has expanded to Advanced Air Mobility (AAM). A tilt rotor type of vertical take-off and landing aircraft has been actively studied and developed. A tilt-rotor aircraft can perform a transition flight between vertical and horizontal flights. A blade pitch angle control system can be used for flight stability during transition flight time. In addition, Individual Blade Control (IBC) can reduce noise and vibration generated in transition flight. This paper proposed Disturbance Observer Based Control (DOBC) and Time Delay Control (TDC) for individual blade control of an Electro-Mechanical Actuator (EMA) based blade pitch angle control system. To compare and analyze proposed controllers, numerical simulations were conducted with DOBC and TDC.

• International Journal of Control, Automation, and Systems
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• v.1 no.4
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• pp.431-443
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• 2003

This paper presents an efficient method to evaluate the performance of an extended stochastic Petri net by simple algebraic operations. The reachability graph is derived from an extended stochastic Petri net, and then converted to a timed stochastic state machine, using a semi-Markov process. The n-th moments of the performance index are derived by algebraic manipulations with each of the n-th moments of transition time and transition probability. For the derivation, three reduction rules are introduced on the transition trajectories in a well-formed regular expression. Efficient computation algorithms are provided to automate the suggested method. The presented method provides a proficient means to derive both the numerical and the symbolic solutions for the performance of an extended stochastic Petri net by simple algebraic manipulations.

• Journal of Ship and Ocean Technology
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• v.8 no.4
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• pp.10-16
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• 2004

A response of a swept wing boundary layer to a single free-stream stationary axial vortex of a limited spanwise extent is considered as an example of typical problems that one can find in laminar-turbulent transition research and control. The response is dominated by streamwise velocity perturbations that grow quasi-exponentially downstream. It is shown that the formation of the boundary layer disturbance occurs for the most part close to the leading edge. The disturbance represents itself a wave packet consisted of the waves with characteristics specific for cross-flow instability. However, an admixture of growing disturbances whose origin can be attributed to transient effects and to a distributed receptivity mechanism is also identified.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.8
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• pp.786-793
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• 2010

This paper proposes a new method called the path-history coverage to generate a test suite to test the state transition behavior of the robot SW component. The proposed method generate a test suite which includes abnormal state transitions based on FSM of target component. Especially the proposed method covers the disadvantage of the mutation test method that the size of the test suite is explosively increasing. Examples including OPRoS Component[1] show the validity of the proposed method.