• Proceedings of the KOSOMBE Conference
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• v.1991 no.11
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• pp.25-29
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• 1991

In the field of prosthesis arm control, tile pattern classification of the EMG signal is a required basis process and also the estimation of force from col looted EMG data is another necessary duty. But unfortunately, what we've got is not real force but an EMG signal which contains the information of force. This is the reason why he estimate the force from the EMG data. In this paper, when we handle the EMG signal to estimate the force, spatial prewhitening process is applied from which the spatial correlation between the channels are removed. And after the orthogonal transformation, which is used in the force estimation process the transformed signal is inputed into the probabilistic model for pattern classification. To verify the different results of the multiple channels, SNR(signal to noire ratio) function is introduced.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.3
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• pp.181-189
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• 2000

The aerodynamic characteristics of large transport vehicle has become more and more important in recent vehicle design to improve driving performance in high speed cruising and raise the product valve with regard to a comfortable driving condition. Hence, detailed knowledge of the flow field around truck coner vane is essential to improve fuel efficiency and reduce the dirt contamination on vehicle body surface. In this study, three-dimensional flow characteristics around corner vane attached to truck cabin were computed for the steady, incompressible, and high speed viscous flow, adopting the RNG k-$\varepsilon$ turbulence model. In order to investigate the influence of configuration and structure of corner vane, computations were carried out for four cases at a high Reynolds number, Re=4.1$\times$106 (based on the cabin height). The global flow patterns, drag coefficient and the distributions such as velocity magnitude, turbulent kinetic energy around the corner vane, were examined. As a result of this study, we could identify the flow characteristics around corner vane for the variation of corner vane length and width. Also, suggest the improved structure to reduce the dirt contamination in cabin side.

• Transactions of Materials Processing
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• v.19 no.6
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• pp.329-336
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• 2010

Ring forging process is more appropriate for high-length and thin walled ring, because it utilizes the forging press and hence does not require heavy-duty ring rolling mill. Although ring forging process is very simple and economic for facilities, the process is not efficient because of multi-forging-step and low material utilization. An effective ring forging process is developed using a hollow ingot. When a hollow ingot is used with a workpiece, the ingot can be forged into a final ring without multi-stage pre-forging process, such as, cogging, upsetting, and piercing, etc.. Finally it has advantages of the material utilization and process improvement because a few reheating and forging process are not necessary to make workpiece for ring forging. The important design variables are the applied plastic deformation energy to eliminate cast structure and make uniform properties. In this study, the mechanical properties after forging of hollow cast ingot were investigated from the experiment using circumferential sectional model. Also, the effects of process variables were studied by FEM simulation on the basis of thermo-visco-plastic constitutive equation. Applied strain is different at each position in length direction because diameter of hollow ingot is different in length direction. The different strain distribution become into a narrow gap by additional plastic deformation during diameter extension process.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.800-811
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• 2018

This paper presents a regenerative braking control scheme for Switched Reluctance Machine (SRM) drive in Electric Vehicles (EVs). The main purpose is to maximize the recovered energy during battery charging by taking into account the nonlinear physical characteristics of the Switched Reluctance Machine. The proposed regenerative braking method employs the back-EMF in the generation process as a complicated position-dependent voltage source. The proposed maximum power recovery (MPR) operation of the regenerative braking is first based on the maximization of the extracted power from the machine and then the maximization of the power transferred to the battery. The maximum power extraction (MPE) from SRM is based on maximizing the energy conversion ratio by the calculation of the optimum PWM switching duty cycle, turn-on, and turn-off angles. By using the impedance matching theorem that allows the maximum power transfer (MPT) of the MPE, the proposed MPR is achieved. The parametric averaged value modeling of the machine phase currents in the chopping control mode is used for MPR realization. By following this model, a nonlinear equivalent input resistance is derived for the battery internal resistance matching. The effectiveness of the proposed regenerative braking method is demonstrated through simulation results and experimental implementation.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.4
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• pp.1136-1146
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• 2015

The purpose of this study was to clarify the meaning of marine officer's self-efficacy, job satisfaction, definition of self-development and factors of determination. It shows that how their self-efficacy affects job satisfaction, self-development and that how their job satisfaction affects self-development. To achieve the purpose of the research, checked the definition and factors of marine officer's duty, self-efficacy, job satisfaction and self-development. Furthermore, cultivated a research model about the factors to influence between self-efficacy and job satisfaction, self-efficacy and self-development, job satisfaction and self-development. A result of hypothesis test by regression analysis is that 11 hypotheses were adopted among 17, and the rest of them were dismissed. The contents of hypotheses were set as follows; self-efficacy and internal job satisfaction, self-efficacy and external job satisfaction, self-efficacy and self-development, job satisfaction and self-development.

• The Journal of Society for e-Business Studies
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• v.14 no.3
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• pp.107-129
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• 2009

The person who realize e-business must understand Information Technology(IT) and business process. Current policy and system should be attained new change for domestic e-business manpower training. Divided for manpower training in new dimension justice about present e-business manpower and manpower classification. The capacity about course of study of e-business manpower and program development classified in a new comer, expert, administrator, manager's process. And the process divided ten details job according to business and functions that achieve in enterprise and major in university. Present capacity that needs in details line of duty by ASK(Attitude, Skill, Knowledge) model and focused for program development.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.9
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• pp.74-82
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• 2013

This paper presents a novel maximum power point tracking for a photovoltaic power (PV) system with a direct control plan. Maximum power point tracking (MPPT) must usually be integrated with photovoltaic (PV) power systems so that the photovoltaic arrays are able to deliver maximum available power. The maximum available power is tracked using specialized algorithms such as Perturb and Observe (P&O) and incremental Conductance (indCond) methods. The proposed method has the direct control of the MPPT algorithm to change the duty cycle of a dc-dc converter. The main difference of the proposed system to existing MPPT systems includes elimination of the proportional-integral control loop and investigation of the effect of simplifying the control circuit. The proposed method thus has not only faster dynamic performance but also high tracking accuracy. Without a conventional controller, this method can control the dc-dc converter. A simulation model and the direct control of MPPT algorithm for the PV power system are developed by Matlab/Simulink, SimPowerSystems and Matlab/Stateflow.

• Journal of Power Electronics
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• v.18 no.1
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• pp.81-91
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• 2018

This paper proposes a double line voltage synthesis (DLVS) strategy for three-to-five phase direct matrix converters. In the proposed strategy, the input and expected output voltages are divided into 6 segments and 10 segments, respectively. In addition, in order to obtain the maximum voltage transfer ratio (VTR), the input line voltages and "source key" should be selected reasonably according to different combinations of input and output segments. Then, the corresponding duty ratios are calculated to determine the switch sequences in different segment combinations. The output voltages and currents are still sinusoidal and symmetrical with little lower order harmonics under unbalanced or distorted input voltages by using this strategy. In addition, the common mode voltage (CMV) can be suppressed by rearranging some of the switching states. This strategy is analyzed and studied by a simulation model established in MATLAB/Simulink and an experimental platform, which is controlled by a DSP and FPGA. Simulation and experimental results verify the feasibility and validity of the proposed DLVS strategy.

• Safety and Health at Work
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• v.6 no.4
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• pp.345-352
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• 2015

Background: Goal-oriented communication of risk of hazards is necessary in order to reduce risk of workers' exposure to chemicals. Adequate training of workers and enterprise priority setting are essential elements. Cleaning enterprises have many challenges and the existing paradigms influence the risk levels of these enterprises. Methods: Information on organization and enterprises' prioritization in training programs was gathered from cleaning enterprises. A measure of enterprises' conceptual level of importance of chemical health hazards and a model for working out the risk index (RI) indicating enterprises' conceptual risk level was established and used to categorize the enterprises. Results: In 72.3% of cases, training takes place concurrently with task performances and in 67.4% experienced workers conduct the trainings. There is disparity between employers' opinion on competence level of the workers and reality. Lower conceptual level of importance was observed for cleaning enterprises of different sizes compared with regional safety delegates and occupational hygienists. Risk index values show no difference in risk level between small and large enterprises. Conclusion: Training of cleaning workers lacks the prerequisite for suitability and effectiveness to counter risks of chemical health hazards. There is dereliction of duty by management in the sector resulting in a lack of competence among the cleaning workers. Instituting acceptable easily attainable safety competence level for cleaners will conduce to risk reduction, and enforcement of attainment of the competence level would be a positive step.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.2
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• pp.36-48
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• 2019

As the importance of Knowledge Management System (KMS) in the military increases, Republic of Korea Army (ROK Army) developed Army Knowledge Portal. Although the members in the military are encouraged to use the portal, few members currently use it. This study was conducted to find variables to predict the user's intention to use the portal, which contributes to activating the use of Army Knowledge Portal in the army. On the basis of Technology Acceptance Model (TAM), ten variables such as perceived ease of use, general information security awareness, information security awareness, expectation for external rewards, expectation for relationships, sense of self-worth, attitude toward compliance with security policy, attitude toward knowledge sharing, intention of non-combat knowledge sharing, and intention of combat knowledge sharing were considered as independent variables. 105 participants on active duty who currently use or have experience to use the portal participated in this study. The results indicated that general information security awareness and information security awareness increases compliance with the information security policy. In addition, the attitude toward knowledge sharing is enhanced by expectations for relationship and sense of self-worth. Based on the results, the authors propose the need for policy alternatives to reinforce the reward system and security policy, which activates the use of Knowledge Portal Service for ROK Army.