• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.61-66
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• 2020

Since the ocean accounts for 70.8 percent of the earth's surface, the success of IoT technology in the marine industry is to collect information from devices placed in a wider range. LPWA is a feature with a wide range of communication and is very suitable for deployment in the ocean. In this paper, the real-sea performance distance experiment was carried out based on Private LoRa, a key technology for executing the electronic phrase real-name system. A private LoRa module based on sx1276 was developed, and Gateway was developed to transfer data received by private LoRa to the server using SKT Cat. M1. After installing gateways at 599 meters above sea level and experimenting with data transmission and reception at 25 km, 40 km and 60 km, we were able to see that the communication success rate was obtained to be 96.1%. 97.1% and 96.2% respectively.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.3
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• pp.120-125
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• 2002

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. In the switching-mode power converter, the output voltage is generally controlled by varying the duty ratio of main switch. When a converter operates in steady state, duty ratio of the converter is kept constant. So the power of switching noise is concentrated in specific frequencies. Generally, to reduce the EMI and improve the immunity of converter system, the switching frequency of converter needs to be properly modulated during a rectified line period instead of being kept constant. Random Pulse Width Modulation (RPWM) is performed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300V/1kW with 5%~30% white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.

• KIISE Transactions on Computing Practices
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• v.20 no.9
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• pp.519-524
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• 2014

The operating systems in the system architecture, which is integrated several applications and modular electronic devices in the same computing device, demand partitioning technology for safety. Thus, operation system requires partition scheduler for partition scheduling. When we design partition scheduler in embedded system, which has small memory and low performance, such as space system, we must consider not only performance but also memory. In this paper, we introduces a linux-based memory efficient partition scheduler using partition bitmap. This partition scheduler demands small memory space and produce low partition switching overhead. The prototype was executed on a LEON4 processor, which is the Next Generation Multicore Processor (NGMP) in the space sector. In evaluation, this prototype shows accuracy, additional memory space and low partition switching overhead.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.41.2-41.2
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• 2011

Recently, scaling down of ULSI (Ultra Large Scale Integration) circuit of CMOS (Complementary Metal Oxide Semiconductor) based electronic devices become much faster speed and smaller size than ever before. However, very narrow interconnect line width causes some drawbacks. For example, deposition of conformal and thin barrier is not easy moreover metallization process needs deposition of diffusion barrier and glue layer. Therefore, there is not enough space for copper filling process. In order to overcome these negative effects, simple process of copper metallization is required. In this research, Cu-V thin alloy film was formed by using RF magnetron sputter deposition system. Cu-V alloy film was deposited on the plane $SiO_2$/Si bi-layer substrate with smooth and uniform surface. Cu-V film thickness was about 50 nm. Cu-V layer was deposited at RT, 100, 150, 200, and $250^{\circ}C$. XRD, AFM, Hall measurement system, and XPS were used to analyze Cu-V thin film. For the barrier formation, Cu-V film was annealed at 200, 300, 400, 500, and $600^{\circ}C$ (1 hour). As a result, V-based thin interlayer between Cu-V film and $SiO_2$ dielectric layer was formed by itself with annealing. Thin interlayer was confirmed by TEM (Transmission Electron Microscope) analysis. Barrier thermal stability was tested with I-V (for measuring leakage current) and XRD analysis after 300, 400, 500, 600, and $700^{\circ}C$ (12 hour) annealing. With this research, over $500^{\circ}C$ annealed barrier has large leakage current. However V-based diffusion barrier annealed at $400^{\circ}C$ has good thermal stability. Thus, thermal stability of vanadium-based thin interlayer as diffusion barrier is good for copper interconnection.

• Korean Journal of Materials Research
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• v.20 no.7
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• pp.370-373
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• 2010

In fabricating plasma display panels, the photolithographic process is used to form patterns of barrier ribs with high accuracy and high aspect ratio. It is important in the photolithographic process to control the refractive index of the photosensitive paste. The composition of this paste for photolithography is based on the $B_2O_3-SiO_2-Al_2O_3$ glass system, including additives of alkali oxides and rare earth oxides. In this work, we investigated the density, structure and refractive index of glasses based on the $B_2O_3-SiO_2-Al_2O_3$ system with the addition of $Li_2O$, $K_2O$, $Na_2O$, CaO, SrO, and MgO. The refractive index of the glasses containing K2O, Na2O and CaO was similar to that of the [BO3] fraction while that of the SrO, MgO and Li2O containing glasses were not correlated with the coordination fraction. The coordination number of the boron atoms was measured by MAS NMR. The refractive index increased with a decrease of molar volume due to the increase in the number of non-bridging oxygen atoms and the polarizability. The lowest refractive index (1.485) in this study was that of the $B_2O_3-SiO_2-Al_2O_3-K_2O$ glass system due to the larger ionic radius of $K^+$. Based on our results, it has been determined that the refractive index of the $B_2O_3-SiO_2-Al_2O_3$ system should be controlled by the addition of alkali oxides and alkali earth oxides for proper formation of the photosensitive paste.

• Journal of Welding and Joining
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• v.33 no.3
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• pp.25-31
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• 2015

Due to environmental regulations (RoHS, WEEE and ELV) of the European Union, electronics and automotive electronics have to eliminate toxic substance from electronic devices and system. Specifically, reliability issue of lead-free solder joint have an increasing demand for the car electronics caused by ELV banning. The authors prepared engine control unit and cabin electronics soldered with Sn-3.0Ag-0.5Cu (SAC305). To compare with the degradation characteristics of solder joint strength, thermal cycling test (TC), power-thermal cycling test (PTC) and series tests were conducted. Series tests were conducted for TC and PTC combined stress test using the same sample in sequence and continuously. TC test was performed at $-40{\sim}125^{\circ}C$ and soak time 10 min for 1000 cycles. PTC test was applied by pulse power and full function conditions during 100 cycles. Combined stress test was tested in accordance with automotive company standard. Solder joint degradation was observed by optical microscopy and environment scanning electron microscopy (ESEM). In addition, to compare with deterioration of bond strength of quad flat package (QFP) and chip components, we have measured lead pull and shear strength. Based on the series test results, consequently, we have validated of series test method for lifetime and reliability of Pb-free solder joint in automotive electronics.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.169-173
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• 1997

Most conventional lithography systems have been oriented to fabricate electronic devices. Therefore, it is not so easy to fabricate large aspect ratios of waveguide patterns with those systems. When considering costs and efficiencies, a laser lithography system provides number of benefit in realizing waveguide patterns. However, because the conventional laser lithography system could make only positive tone masks, it is inconvenient in determining the direction of the waveguide. A simple and reliable technique to produce negative tone masks was developed by using the laser beam writing. This technique was not sensitive to environmental situations such as dust, vibration, intensity variation. Making use of the technique a variety of device patterns such as Y-branch, directional coupler, and highly smooth S-shape bend could be successfully fabricated with a good contrast.

• The Journal of Society for e-Business Studies
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• v.14 no.2
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• pp.117-130
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• 2009

Lots of applications that represent and utilize geographic information on the Web have emerged on the Web. In addition, personal electronic devices equipped with GPS function, which can record personal location information in real time, are being increasingly adopted by people. Such geographic information enables Internet business companies to provide users more useful services based on the location information. Most successful Internet business companies have adopted and utilized Web 2.0 technologies, which promote users' participation and emphasize openness and information sharing. Especially, using open APIs (Application Programming Interfaces) can reduce the costs of a program development. In this study, we design and develop a banner advertisement system based on geographic information using open APIs. We propose a business model using the advertisement system, and a prototype system has been illustrated in order to explain the proposed business model. Finally, we summarize the benefits of our system by describing factors generating values of the proposed business model. Hopefully, main ideas proposed in this paper can be applied to real industry sectors that use geographic information widely such as travel, real estate and so on.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.7
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• pp.50-55
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• 1999

We have fabricated optical waveguide which utilizes intermixing of InGaAs/InGaAsP multi quantum well separate confinement heterostructure. The waveguide was fabricated by reactive ion etching technique using $CH_4/H_2$ gas mixture, and the width and depth of the waveguide ware $5{\mu}m$ and $1.2{\mu}m$, respectively. The propagation loss of the waveguide was measured by Fabry-Perot interference phenomena using tunable laser. For the waveguide after $800^{\circ}C$, 30s heat treatment, the measured loss was 3.76dB/cm and 3.95dB/cm for TE and TM mode, respectively. This value is very small compared to other waveguide made by IFVD technique. Hence, this technique can applied to integration of waveguide and electronic devices.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.61-66
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• 2008

Recently, portable devices which require small area and low power consumption employ applications using 3D graphics such as 3D games and 3D graphical user interfaces. We propose an efficient clipping engine algorithm which is suitable in 3D graphics pipeline. The clipping operation is divided into two steps: one is the selection process in the transformation engine and the other is the pixel clipping process in the scan conversion unit. The clipping operation is possible with addition of simple comparator. The clipping for the Y-axis is achieved in the edge walk stage and that for the X and Z-axis is performed in the span processing. The proposed clipping algorithm reduces the operation cycles and the area of of 3D graphics pipelines. We designed a 3D graphics pipeline with the proposed clipping algorithm using Verilog-HDL and verifies the operation using an FPGA.