• Journal of the Institute of Convergence Signal Processing
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• v.19 no.2
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• pp.61-67
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• 2018

Welding preheating means that the surface of the base material to which the metal is welded before the main welding is heated to a constant temperature. It prevents the cracks of the adjacent influences such as reduction of material hardening degree by controlling the cooling rate, suppression of segregation of impurities, prevention of thermal deformation, and moisture removal. For this reason, it is a necessary operation for high quality welding. Induction heating is an efficient heating method that converts electric energy into heat energy by applying electromagnetic induction phenomenon. Compared with combustion heat generated by gas and liquid, it is clean, stable, and economical as well as rapid heating. It can be heated regardless of the shape, depth and material of the heating body by modifying the shape of the frequency and the coil with a simple structure. In this paper, we implemented a low frequency welding preheating system using induction heating technique and observed the temperature changes of coil resistance, inductance and automotive transmission parts according to the height of each transmission in winding coil for three kinds of automotive transmission parts. We confirmed that the change of current is a very important factor in the low frequency heating.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.115-130
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• 2012

These days, most of safety-critical systems, which are systems those failures or malfunction may result in death or serious injury to people, or loss or severe damage to social systems, or environmental harm, are being built of embedded software or loaded controlling software systems on computers, electrical and electronic components or devices. There are a lot kind of fault analysis methods to evaluate safety of the safety-critical systems equipped computers, electrical and electronic components or devices with software. However, the only assessment method to evaluate software safety of a safety-critical system is not enough to analysis properly on account of the various types and characteristic of software systems by progress of information technology. Therefore, this paper proposes the integrated evaluation method and carries out a case study for the software safety of safety-critical system which embedded or loaded software sizes are small and control response times are not sensitive by use of two security analysis methods which are Fault Tree Analysis (FTA) and Fault Modes and Effect Analysis (FMEA) for ubiquitous healthcare system.

• Composites Research
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• v.31 no.4
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• pp.128-132
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• 2018

Multi-material design with metals and composites can keep structural functions as well as reduce the weight of automotive parts. However, recycling of automotive parts should be considered due to the increasing emphasis on the environments and pollutions. We derived the key issues for increasing the recycling rate of automotive parts by carrying out a survey targeting representatives and workers related with automotive recycling. The core of the key issues was the separation technology of adhesively bonded metal-composite hybrid structures, so we conducted the basic research and suggested the separation technology which can easily be adopted into the recycling industries.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.941-944
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• 2012

Microprocessor is widely used in various industries. So it is very important to learn about it. But it is very difficult because students must know about both hardware and software of it. Student usually learn about it with a complete educational product in many technical high school. It make them to have no chance to mixed various electronic parts such as sensors, motors and so on. It cause them to low the creative product making ability. So we adjust new course with the arduino instead of the complete educational product to microprocessor education. It help student to high the electronic part mixing ability and the creative electronic product making ability.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.161.2-161.2
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• 2017

희토류계 영구자석은 대부분의 전기, 전자 제품의 핵심부품이며 높은 보자력, $BH_{max}$를 가지고 있어 자기기록저장매체, MEMS(엑츄에이터), 소형센서, 소형모터 등의 응용 분야에 적용시키기 위해 다양한 연구들이 진행되고 있다. 그러나 영구자석에 들어가는 희토류계 원소의 수급의 어려움 및 가격의 문제점으로 친환경 자석으로의 전환 및 희토류나 중희토류를 사용하지 않는 비희토류계 영구자석을 제조 및 개발하는데 많은 연구가 이루어지고 있다. 이 중 Fe-N 계 자성물질인 $Fe_{16}N_2$는 포화 자화 값이 현재까지의 비희토류계 자성물질 중 가장 높은 값(240emu/g)을 나타내며 상대적으로 높은 결정자기이방성 상수를 가지고 있어 비희토류계 영구자석 물질 중 하나로 주목받으며 연구되어지고 있다. 본 연구에서는 $Fe_{16}N_2$ 박막을 얻기 위해 DC Magnetron Sputtering 방법을 이용하여 Si wafer 위에 박막을 증착하고 증착시간에 따라 두께를 제어하여 제조한 후 박막의 미세구조, 상 분석, 자성 특성을 관찰을 통해 최적의 공정 조건을 찾고자 하였다. 증착 시간에 따른 박막의 성장 속도는 일정하게 증가하였으며, 증착 시간의 증가에 따라 박막 내 $Fe_{16}N_2$의 상대적인 분율은 감소하였다. 모든 공정 조건에서 $Fe_3N$, $Fe_4N$, $Fe_{16}N_2$ 상들이 섞여 성장하였으며 XRD를 통한 상분석과 더불어 VSM을 통한 자성 특성을 분석해본 결과 $Fe_{16}N_2$의 분율을 가장 높게 성장된 공정 조건은 증착 시간이 10분이며 박막의 두께가 ${\sim}1{\mu}m$ 일 때, 최적의 조건을 얻을 수 있었으며, 이 때의 자성 특성을 분석한 결과 ~2.45T의 포화 자화 값과 ~1.41T의 잔류 자화 값을 얻을 수 있었다.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.349-355
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• 2020

Social robots are attracting attention as an alternative to social problems in modern society, and the need for modularization has been raised to efficiently manage various robots. The study aims to reestablish the concept of 'Personal social service robot' and propose a new modularization method to apply it. For this study, literature research about the definition of social robots and service robots is conducted. In addition, we investigated the modularization of robots and analyzed the modularization cases of service robots. Based on this, we have deducted considerations for applying social service robot modularization and proposed a new modularization. This study divided the module into active module and passive module according to whether it is electric or electronic component of the module, and the active module was again classified into basic module and additional module according to the basic and replacement type of the robot. The modularization was verified by making the prototype of the actual robot.

• Clean Technology
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• v.18 no.4
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• pp.373-378
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• 2012

The end-of-life vehicles (ELV) are important recycling sources, and there are several stages involved in the recycling such as dismantling, shredding, and treatment of shredder residues (ASR). The legal recycling rate should be at least 95% on and after 2015, while we need a proper system to monitor recycling of ELV components and to calculate the practical recycling rate. The paper suggests a monitoring system that calculates practical recycling rates of dismantled components by use of a database of standard recycling rate as well as a web-based monitoring, which is linked to the Eco Assurance system for electric & electronic equipment and vehicle (EcoAS). Also the system supports dismantling and monitoring process by incorporating a standard vehicular component database, which facilitates recording dismantled weight data but also monitoring of dismantled components.

• Journal of the Korean Society of Safety
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• v.11 no.1
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• pp.27-38
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• 1996

The aim of this paper is to develop more fast algorithm for evaluation of the reliability of networks and system. It is illustrated with examples. This paper derived the algorithm to calculate the acyclic directed graph G(deals with the problem of the s-t graph). The language PASCAL was used to implement the algorithm. Three Examples are calculated and the calculation time is shorter than the time by program in $\ulcorner$21$\lrcorner.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.296-302
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• 2019

In this study, a basic durability assessment was performed by selecting the main part of a trial product of a shale shaker, which is one of components for a mud circular system. For a preliminary durability assessment, it was assumed that the lifetime of the bearing for the vibrator motor and the stiffness of the support spring are affected by the vibration when the motor operates continuously. In the case of the motor, the initial p-p level was 0.72 g, but after 100 hours of operation, the p-p level was rapidly increased to 1.26 g. Bearing defects could be estimated through ball defect frequency analysis. In the case of the spring, the stiffness of the spring was reduced by approximately 3.78% at the end of 2,000 hours of the fatigue-durability test by applying excitation conditions to shale shaker body. In the future, we will analyze the influence of the particle removal efficiency of the shale shaker.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.3
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• pp.441-447
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• 2020

In a situation in which around 50 million metric tons of electrical and electronic products is generated globally per year, the total installed base of Internet of Things (IoT) devices is projected to amount to around 75 billion worldwide by 2025. However, there is very little research on identification schemes for end-of-life treatment (EoLT) of IoT devices. To address this issue, this paper proposes new identifiers including EoLT information such as recyclability rate (Rcyc) and recoverability rate (Rcov) of an IoT device, recycling rate (RCR) and recovery rate (RVR) of each part in the IoT device, etc. and implements them by using object identifier (OID), mobile radio frequency identification (RFID) and quick response (QR) code. The implemented OID and mobile RFID can be used with cooperation of a remote server via communication networks and the implemented QR code can be used simply with a smartphone app.