• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4975-4983
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• 2010

In this paper, the ordinariest and strongest simulator that many used to power electronics circuits and many different control technology can apply to more easily understand modeling the element, PSPICE and MATLAB are adapted a micro IGBT, a macro IGBT, PWM generator and to library moeling of validity of the Induction motor is interpreted. Micro IGBT model of demagnetization quality proved for modeling accuracy to through experiment, macromodel IGBT were simulated which the applied to voltage type PWM inverter to the cyclo-converter and induction motor of demagnetization.

• Journal of Internet of Things and Convergence
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• v.3 no.2
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• pp.15-20
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• 2017

The purpose of this study is to understand the concept of transformative learning and the meaning and process of learning. Transformative learning explains that learning takes place in three aspects. First, Instrumental learning takes place in the process of acquiring knowledge based on facts, such as hypothesis testing. Secondly, Communicative learning recognizes the meaning of other people's thoughts or social norms, cultures and values through language. Thirdly, emancipatory learning makes through critical self-reflection by understanding oneself on the basis of psychological and cultural assumptions. The implications of outplacement convergence education, is that main purpose of outplacement education is to build theory and shift the perspective to learning conversion in general operation practice. The content of the outplacement convergence education is that it should shift from instrumental learning to communicative and emancipatory learning.

• Journal of Korea Foundry Society
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• v.40 no.3
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• pp.76-84
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• 2020

The effects of Alloying Element and Heat Treatment on the mechanical properties of ductile cast iron poured into shell stack molds were investigated. The strength and hardness were increased and the elongation was decreased roughly with the increased amounts of tin and copper added, respectively. Those were greatly increased with the increased amount of tin added and the elongation was roughly decreased with it. In the simultaneous addition of copper and tin, the strength and hardness of the tin increased, but the elongation rate decreased. Those were greatly increased and this was decreased with normalizing. In the case of specimens with smaller section sizes during austempering processing, the strength and hardness were higher than those with larger sections, but the elongation rate was lower.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.136-141
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• 2012

Performance improvement of local exhaust system used in toilet and cooking place are main concern in a field of ventilation. In Korea, There are many high riser residential apartments in recent years. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depends on stack effect. This study investigates on the performance improvement of terminal device, roof fan, of vertical spiral duct used in high riser residential apartments. This paper focuses mainly on the effect of accessories, number or shape of blades, composed of roof fan with function of exhaust air volume of toilet and cooking place. Roof fan with 10 blades is observed at optimum exhaust performance in this study.

• Journal of the Korean institute of surface engineering
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• v.52 no.4
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• pp.187-193
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• 2019

Electroless Ni-P coatings are widely used in the chemical, mechanical, and electronic industries because of their excellent wear and abrasion resistance. In this study, the effect of $TiO_2$ particles of composite coating was investigated. To improve the corrosion resistance, electroless $Ni-P-TiO_2$composite coating was studied by varying the $TiO_2$ content. The morphology and phase structure of $Ni-P-TiO_2$ composite coatings were analyzed by scanning electron microscopy(SEM), X-ray diffractometry(XRD) and X-ray photoelectron spectroscopy(XPS). The result showed that $Ni-P-TiO_2$composite coating is composed of Ni, P, Ti and O. It exhibits an amorphous structure, high hardness and good corrosion resistance to the substrate. $Ni-P-TiO_2$ composite coatings have higher open circuit potential than that of the substrate, which obtained at $TiO_2$ content of 5.0 g/L optimal integrated properties.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.3
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• pp.117-124
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• 2021

The development of IOT technology and artificial intelligence technology is promoting the smartization of manufacturing system. In this study, data extracted from acceleration sensor and current sensor were obtained through experiments in the cutting process of SKD11, which is widely used as a material for special mold steel, and the amount of tool wear and product surface roughness were measured. SVR (Support Vector Regression) is applied to predict the roughness of the product surface in real time using the obtained data. SVR, a machine learning technique, is widely used for linear and non-linear prediction using the concept of kernel. In particular, by applying GSVQR (Generalized Support Vector Quantile Regression), overestimation, underestimation, and neutral estimation of product surface roughness are performed and compared. Furthermore, surface roughness is predicted using the linear kernel and the RBF kernel. In terms of accuracy, the results of the RBF kernel are better than those of the linear kernel. Since it is difficult to predict the amount of tool wear in real time, the product surface roughness is predicted with acceleration and current data excluding the amount of tool wear. In terms of accuracy, the results of excluding the amount of tool wear were not significantly different from those including the amount of tool wear.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.255-260
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• 2021

The importance of electric vehicles is gradually increasing due to the recent depletion of fossil fuels. In order to use an electric vehicle, the battery built into the vehicle must be frequently charged. Electric vehicles has very good performance in terms of noise and vibration. However, due to the limitations of the battery, the mileage is considerably shorter than that of an internal combustion engine vehicle once it is charged, and the battery charging time is relatively long compared to the refueling time. There are two types of charging methods for electric vehicle batteries: plug-in and wireless charging. In this paper, we introduced the wireless charging technology for electric vehicles and the current state of technology development and standards in major countries.

• Journal of the Korean institute of surface engineering
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• v.52 no.3
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• pp.156-162
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• 2019

Electroless Ni-P coatings are widely used in the chemical, mechanical, and electronic industries because of their excellent wear and abrasion resistance. In this study, The influence of pH values on properties of Ni-P-PTFE composite coatings was investigated. To improve mold lubrication, Ni-P-PTFE composite coatings at different pH value were studied. The morphology and phase structure of Ni-P-PTFE composite coatings were analyzed by scanning electron microscopy(SEM) and X-ray diffractometry(XRD). The result showed that Ni-P-PTFE composite coating is composed of Ni, P and PTFE. It exhibits an amorphous structure and good Corrosion Resistance to the substrate. Ni-P-PTFE composite coatings have higher open circuit potential than that of the substrate, which obtained at pH value of 5.0 optimal integrated properties.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.2
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• pp.150-154
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• 2019

In the design of semiconductor integrated circuits, ESD is one of the important issues related to product quality improvement and reliability. In particular, as the process progresses and the thickness of the gate oxide film decreases, ESD is recognized as an important problem of integrated circuit design. Many ESD protection circuits have been studied to solve such ESD problems. In addition, the proposed device can modify the existing SCR structure without adding external circuit to effectively protect the gate oxide of the internal circuit by low trigger voltage, and prevent the undesired latch-up phenomenon in the steady state with high holding voltage. In this paper, SCR-based novel ESD(Electro-Static Discharge) device with the high holding voltage has been proposed. The proposed device has the lower triggering voltage without an external trigger circuitry and the high holding voltage to prevent latch-up phenomenon during the normal condition. Using TCAD simulation results, not only the design factors that influence the holding voltage, but also comparison of conventional ESD protection device(ggNMOS, SCR), are explained. The proposed device was fabricated using 0.35um BCD process and was measured electrical characteristic and robustness. In the result, the proposed device has triggering voltage of 13.1V and holding voltage of 11.4V and HBM 5kV, MM 250V ESD robustness.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.649-651
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• 2021

In Korea, there are around 30,000 cardiac arrest patients annually. Gradually the number is increasing. Against this background, CPR education and publicity programs were expanded nationwide, but the rate of witness CPR by the general public was 4.4%, which is significantly lower than the 20%~70% rate in other countries. Therefore, in this paper, we analyzed the factors affecting the performance of CPR by witnesses who discovered cardiac arrest patients. Based on the results, an application planning and development study was conducted to provide users with correct cardiorespiratory response tips and step-by-step CPR guidelines to help users effectively assist in increasing the rate of CPR by general eyewitnesses.