• Journal of Internet of Things and Convergence
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• v.7 no.3
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• pp.63-68
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• 2021

Domestic electric heater manufacturers are focusing on technology development to improve the efficiency of existing products. The electric heater for ship fuel is large in size and has high difficulty in miniaturization/high efficiency, so there are not many companies that try to develop technology yet. The existing electric heater has a structure of low heating efficiency because the contact time with the heat exchange tube of the heating medium is very short because the flow path of the ship engine fuel is monotonous. Since it is manufactured in a tubular shape, the volume is very large regardless of the heating efficiency. As a result, the tubular electric heater device applied by overseas advanced companies has difficulty in maintaining and repairing because it is necessary to decompose all tubular heaters when a specific part of the inside is damaged and if the heat exchange tube is damaged, all the heat exchange tubes must be decomposed. In this study, a basic study on plate type electric heaters capable of heating 10 tons of ship engine fuel per hour and setting a maximum temperature of up to 150℃ was conducted through a 250kW capacity plate type electric heater.

• Journal of vocational education research
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• v.37 no.4
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• pp.23-44
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• 2018

The purpose of the study was to examine the vocational competency of students enrolled in vocational high schools including specialized vocational high school and meister vocational high school, and vocation program of general high school. We analyzed their vocational competency, based upon the vocational competency data of KCCI (Korea Chamber of Commerce & Industry). The results were as follow. First, latent profiles of subjects were categorized into four folds: general cognition-low adaption, cognition adaption general, pursuit of job adaption, low cognition-job mal-adaption. Each percentage of four groups was 39%, 30%, 11%, and 20%. Second, mainly, specialized vocational high school pattern is matched with vocational high schools' pattern. However, the cognitive competency of students in meister vocational high school was higher than that of student in vocation program of general high school. Third, latent profile group was clarified in terms of non-cognition aspect. Fourth, The higher the job adaption is, the higher the career decision level. We suggested some policy implications for improve the vocational competency.

• Journal of Internet of Things and Convergence
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• v.10 no.1
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• pp.1-6
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• 2024

In order to increase the use of electric vehicles (EVs) and minimize grid strain, microgrid using renewable energy must take an important role. Microgrid may use fossil fuels such as small diesel power, but in many cases, they can be supplied with energy from renewable energy, which is an eco-friendly energy source. However, renewable energy such as solar and wind power have variable output characteristics. Therefore, in order to meet the charging and discharging energy demands of electric vehicles and at the same time supply load power stably, it is necessary to review the configuration of electric vehicle charging infrastructure that utilizes diesel power or electric vehicle-to-grid (V2G) as a parallel energy source in the microgrid. Against this background, this study modelized a microgrid that can stably supply power to loads using solar power, wind power, diesel power, and V2G. The proposed microgrid uses solar power and wind power generation as the primary supply energy source to respond to power demand, and determines the operation type of the load's electric vehicles and the rotation speed of the load synchronous machine to provide stable power from diesel power for insufficient generations. In order to verify the system performance of the proposed model, we studied the stable operation plan of the microgrid by simulating it with MATLAB /Simulink.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.7
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• pp.550-559
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• 2018

The effectiveness of deep neural networks (DNNs) for detection and classification of micro-Doppler signals generated by human walking and background noise sources is investigated. Previous research included a complex process for extracting meaningful features that directly affect classifier performance, and this feature extraction is based on experiences and statistical analysis. However, because a DNN gradually reconstructs and generates features through a process of passing layers in a network, the preprocess for feature extraction is not required. Therefore, binary classifiers and multiclass classifiers were designed and analyzed in which multilayer perceptrons (MLPs) and DNNs were applied, and the effectiveness of DNNs for recognizing micro-Doppler signals was demonstrated. Experimental results showed that, in the case of MLPs, the classification accuracies of the binary classifier and the multiclass classifier were 90.3% and 86.1%, respectively, for the test dataset. In the case of DNNs, the classification accuracies of the binary classifier and the multiclass classifier were 97.3% and 96.1%, respectively, for the test dataset.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.161-170
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• 2012

There are many factors to consider when attempting to improve the efficiency of fuel cell operation, such as the operation temperature, humidity, stoichiometry, operation pressure, geometric features, etc. In this paper, the effects of the operation pressure were investigated to find the current density and water saturation behavior on a cross section designated by the design geometry. A two-dimensional geometric model was established with a gas channel that can provide $H_2$ to the anode and $O_2$ and water vapor to the cathode gas diffusion layer (GDL). The results from this numerical modeling revealed that higher operation pressures would produce a higher current density than lower ones, and the water saturation behavior was different at operation pressures of 2 atm and 3 atm in the cathode GDL. In particular, the water saturation ratios are higher directly below the collector than in other areas. In addition, this paper presents the dependence of the velocity behavior in the cathode on pressure changes, and the velocity fluctuations through the GDL are higher in the output area than in inlet area. This conclusion will be utilized to design more efficient fuel cell modeling of real fuel cell operation.

• Industry Promotion Research
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• v.2 no.1
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• pp.101-106
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• 2017

The purpose of this study is to analyze the effects of individual characteristics of college students on the basic skills of the profession. The results of this study are as follows. First, the effect of personal characteristics of college students on self - development ability was significantly influenced by outward personality (.423) at p <.001 level. Second, introspective personality (p <.05, ${\beta}=.268$) and outward personality (p <.001, ${\beta}=5.862$) had a significant effect on the information ability and $R^2=.389$ showed an explanatory power of 38.9%. Third, personal characteristics did not have a statistically significant effect on interpersonal abilities. Fourth, personal characteristics are related to self - development ability and outward personality (.144), self - development ability and information ability (.201), self - development ability and introvert personality (.120) There is a correlation. The purpose of this study was to investigate the effects of job characteristics on the basic competence of the upper and lower group through the diagnosis of the basic competence of individual characteristics and to verify the effectiveness of the study.

• Journal of the Korean Applied Science and Technology
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• v.37 no.3
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• pp.516-525
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• 2020

The densities of aqueous solutions of the amphiphile 2-(2-hexyloxyethoxy)ethanol (C₆E₂) were measured at 279.15 K and 282.15 K by vibrating-tube densitometry. Then using the density data of the binary C₆E₂ (1)/water(2) system, the excess volumes and partial molar volumes were determined at various compositions. Excess volume V^E exhibits negative deviation for the whole region of composition, which implies relatively stronger attraction between molecules. At the C₆E₂ mole fraction of around 0.45, V^E was at its minimum. Partial molar volume ${\bar{V}}_1$ increases monotonously with the mole fraction x₁(=x) and ${\bar{V}}_2$ decreases with x. Any particular point in ${\bar{V}}_1$ and ${\bar{V}}_2$, which may point to molecular association, was unobserved.

• Journal of IKEEE
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• v.21 no.4
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• pp.368-374
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• 2017

In this Paper, we developed a low power type LED security light using LED lighting that substitutes a 220[V] commercial power source for a solar cell module instead of a halogen or a sodium lamp. in addition, a PWM type drive control circuit is designed to minimize the heat generation problem and the drive current of the LED drive controller. in developed system, The light efficiency measurement value is 93.6[lm/W], and a high precision temperature sensor is used inside the controller to control the heat generation of the LED lamp. In order to eliminate the high heat generated from the LED lamp, it is designed to disperse quickly into the atmosphere through the metal insertion type heat sink. The heat control range of LED lighting was $50-55[^{\circ}C]$. The luminous flux and the lighting speed of the LED security lamp were 0.5[s], and the beam diffusion angle of the LED lamp was about $110[^{\circ}C]$ by the light distribution curve based on the height of 6[m].

• Journal of Practical Engineering Education
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• v.15 no.3
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• pp.557-570
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• 2023

The purpose of this study is to develop a digital-based non-face-to-face instructional design model for national public servants. For this purpose, we reviewed the direction of non-face-to-face instructional design based on previous research, and interviewed a total of 10 instructors and learners with experience in non-face-to-face education to identify the success factors of non-face-to-face instructional design for government employees. In addition, to ensure the validity of the instructional design model, a Delphi survey was conducted with experts in instructional design and educational management. As a result, the digital-based instructional design model for national public servants reflects the importance of learning objectives and content design to enhance learning motivation and improve educational effectiveness, and includes detailed implementation plans to support specific and clear performance activities for instructors in non-face-to-face education situations. The instructional design model developed through this study can be expanded as a standard for improving the quality of education in public human resource development, and can be used as a teaching and learning guide according to learner types and characteristics.

• Journal of Practical Engineering Education
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• v.16 no.3_spc
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• pp.309-325
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• 2024

The purpose of this study was to develop self-evaluation criteria for objective verification and performance analysis of LINC 3.0. To achieve this goal, evaluation indicators in the fields of human resources development and skill development and commercialization were developed and their validity was verified. We investigated previous evaluation-related studies and similar cases to construct an evaluation model and system and develop indicators. The validity of the developed evaluation indicators was secured through two round Delphi surveys. As a result of the research, LINC 3.0 evaluation indicators can be divided into the field of human resources development and skill development and commercialization. A total of 66 evaluation indicators were developed. CIPP in the field of human resources development was developed with 13 categories and 38 evaluation indicators, and CIPP in the field of skill development and commercialization was developed with 12 categories and 28 evaluation indicators. The significance of this study is that it suggests a way to increase the objective verification and validity of the university industry-academia cooperation model by developing self-evaluation indicators for the LINC 3.0 project. The evaluation indicators developed in the research need to be continuously upgraded based on field usability, and it is necessary to improve the quality and competitiveness of university education by sharing and spreading excellent affairs.