• Journal of Welding and Joining
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• v.32 no.3
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• pp.74-80
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• 2014

Due to environmental regulations (RoHS, WEEE and ELV) of the European Union, electronics and automotive electronics have to eliminate toxic substance from their devices and system. Especially, reliability issue of lead-free solder joint is increasing in car electronics due to ELV (End-of-Life Vehicle) banning from 2016. We have prepared engine control unit (ECU) modules soldered with Sn-40Pb and Sn-3.0Ag-0.5Cu (SAC305) solders, respectively. Degradation characteristics of solder joint strength were compared with various conditions of automobile environment such as cabin and engine room. Thermal cycle test (TC, $-40^{\circ}C$ ~ ($85^{\circ}C$ and $125^{\circ}C$), 1500 cycles) were conducted with automotive company standard. To compare shear strength degradation rate with eutectic and Pb-free solder alloy, we measured shear strength of chip components and its size from cabin and engine ECU modules. Based on the TC test results, finally, we have known the difference of degradation level with solder alloys and use environmental conditions. Solder joints degradation rate of engine room ECU is superior to cabin ECU due to large CTE (coefficient of thermal expansion) mismatch in field condition. Degradation rate of engine room ECU is 50~60% larger than cabin room electronics.

• The Korean Journal of Applied Statistics
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• v.32 no.5
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• pp.683-692
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• 2019

It is hard to imagine teaching statistics without the help of technology. Technology is changing the way in which the content of introductory statistics is taught and the forms of textbook used. Almost all students carry mobile devices all the time that allows them to learn anytime and anywhere if we provide them with statistical electronic textbook. The use of smartphones for asking questions and finding answers in class, it can encourage students to engage more in lectures. This paper analyzes the data obtained using e-textbook in traditional classroom and discusses the future research direction of e-textbooks.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.1
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• pp.1-5
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• 2011

In this paper, we introduce knowledge sharing platform for production technology. Surface mount technology (SMT) is one of the important production technologies to fabricate electronic devices. The production technology of the SMT, however, has been propagated from an experienced worker to an inexperienced worker in a manufacturing field. The objective of the knowledge sharing platform is to convert the production experiences like a solder printing knowhow into quantitative values, to construct the database of the process technologies, and to share the technologies systematically via web portal service. In addition, the knowledge sharing platform contains the total production process of mobile products, the information of experts and facilities, and recent R&D output. In this manner, the knowledge sharing platform for production technology could strengthen the technological competitiveness of small and medium manufacturing companies in Korea.

• The Journal of Korean Association of Computer Education
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• v.16 no.3
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• pp.31-39
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• 2013

We developed a smart learning system by using the 'bring your own device' concept, which means the policy of permitting teacher and learners to bring personally owned mobile devices such as laptops, tablets, smart phones, etc. and applied the system to school classes. In addition, we analyzed the learner's satisfaction related to interfaces, interactions, applications, technical support, and evaluation areas. The evaluation system consists of App program for tablet PC's and smartphones, web program for desktop PC and electronic teaching desk, and server program for evaluation and database. Because all the teaching materials, feedback data and evaluation materials about learners are stored on the server, students can receive the necessary data through real-time feedback using their smartphones and desktop PC's. As a result, it could increase educational achievement with interest in learning.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.4
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• pp.448-457
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• 1998

A neural network based control algorithm with fuzzy compensation is proposed for the automated adjustment in the production of electronic end-products. The process of adjustment is to tune the variable devices in order to examine the specified performances of the products ready prior to packing. Camcorder is considered as a target product. The required test and adjustment system is developed. The adjustment system consists of a NNC(neural network controller), a sub-NNC, and an auxiliary algorithm utilizing the fuzzy logic. The neural network is trained by means of errors between the outputs of the real system and the network, as well as on the errors between the changing rate of the outputs. Control algorithm is derived to speed up the learning dynamics and to avoid the local minima at higher energy level, and is able to converge to the global minimum at lower energy level. Many unexpected problems in the application of the real system are resolved by the auxiliary algorithms. As the adjustments of multiple items are related to each other, but the significant effect of performance by any specific item is not observed. The experimental result shows that the proposed method performs very effectively and are advantageous in simple architecture, extracting easily the training data without expertise, adapting to the unstable system that the input-output properties of each products are slightly different, with a wide application to other similar adjustment processes.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.4
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• pp.371-380
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• 2001

In this paper, lightness mapping for uniform color distribution and gamut mapping for maximum chroma reproduction are proposed. In the conventional lightness mapping, the average lightness difference between the two gamut is increased and different color changes in bright and dark regions are also increased. To solve these problems, a lightness mapping is proposed that minimizes the lightness difference of the cusps at each hue angle and produces same color changes in bright and dark regions. Also, gamut mapping that utilize variable anchor point and an anchor point are proposed for maximum chroma reproduction and uniform color change. Accordingly, the proposed algorithm can reproduce high quality images with low-cost color devices.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.4
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• pp.53-59
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• 2000

Based on the polarization selectivity of fiber-to-planar waveguide coupler, a novel fiber optic polarizer has been designed and fabricated. The large structural birefringence of a metal-clad planar waveguide enables the polarizer to have wide operating wavelength range. The polymer and gold were used for the guiding layer and cladding layer of the planar waveguide, respectively. The experimental results showed that either TE or TM polarized lightwave could be created by adjusting the thickness of planar waveguide. Operating wavelegth range satisfying more than 16㏈ polarization extinction ratio was 130nm. The average insertion loss of fabricated devices was order of 0.5㏈.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1722-1724
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• 1996

Enhancing the electrical conductivity of the ultrathin organic films is one of the important factors for the development of molecular electronic devices. The Langmuir-Blodgett(LB) technique has recently been attracted as out of the ways of deposition ultrathin films. We have studied manufacturing conditions and physical properties of Hexadecyl Dipyridinium-$(TCNQ^-)_2$ LB films made by Kuhn type apparatus. A ${\pi}-A$ isotherm shows that a limiting area is around $180{\AA}^2/molecule$ and a proper surface pressure for a deposition is around 22mN/m. A transfer ratio shows that Hexadecyl Dipyridinium-$(TCNQ^-)_2$ is able to be deposited as an Y-type. UV /visible absorption spectra shows that TCNQ dimer peak is apeared at about 600nm in LB films. In solution, $TCNQ^-$ peak is observed at about 400nm and charge transfer band at $830{\sim}900nm$. A horizontal conductivity of the Hexadecyl Dipyridinium-$(TCNQ^-)_2$ LB film is about $10^{-7}(S/cm)$.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.2
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• pp.114-121
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• 2016

This paper is Instant space vector PWM(Pulse Width Modulation)power conversion devices in switching power semiconductors from my generation to losses and switching when the voltage surge and current surge of electronic noise(EMI: Electro Magnetic Interference / RFI: Radio Frequency Interference)to effectively minimize the power soft-switching power conversion circuit topologies of auxiliary resonant DC tank for the purpose of high performance realization of the electric power conversion system by the high-speed switching of a semiconductor device(AQRDCT simultaneously : an active auxiliary resonance using auxiliary Quasi-resonant DC tank)DC link snubber switch has adopted a three-phase voltage inverter. AQRDCL proposed in this paper can reduce the effective and current peak stress of the power semiconductors of the auxiliary resonant snubber circuit compared to the conventional active-resonant DC link snubber, it is not necessary to install the clamp switch of the auxiliary resonant DC link, DC the peak current and power loss of the bus line can be reduced.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2251-2252
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• 2008

Recently, voltage sag from sudden increasing loads is also one of the major problems inside the utility network. In order to compensate the voltage sag problem, power compensation device systems could be a good solution method. In case of voltage sag, an energy source is needed to overcome the energy loss caused by the voltage sag. Superconducting Magnetic Energy Storage (SMES) is a very promising source of this energy due to its fast response of charging and discharging time. Before constructing the power electronic delivering system for the SMES, it is necessary to simulate the system to understand its behavior. Nowadays, a lot of devices have been developed to compensate voltage sag such as Dynamic Voltage Restorer (DVR), Distribution Static Compensator (D-STATCOM) and Uninterruptible Power Supply (UPS). In this paper, focus is given only on DVR system which will be simulated by using PSCAD/EMTDC software.