• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.12
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• pp.565-569
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• 2006

Plasma enhanced chemical vapor deposition(PECVD) is a well established technique for the deposition of hydrogenated film of silicon nitride (SiNx:H), which is commonly used as an antireflection coating as well as passivating layer in crystalline silicon solar cell. PECVD-SiNx:H films were investigated by varying the deposition and annealing conditions to optimize for the application in silicon solar cells. By varying the gas ratio (ammonia to silane), the silicon nitride films of refractive indices 1.85 - 2.45 were obtained. The film deposited at $450^{\circ}C$ showed the best carrier lifetime through the film deposition rate was not encouraging. The film deposited with the gas ratio of 0.57 showed the best carrier lifetime after annealing at a temperature of $800^{\circ}C$. The single crystalline silicon solar cells fabricated in conventional industrial production line applying the optimized film deposition and annealing conditions on large area substrate of size $125mm{\times}125mm$ (pseudo square) was found to have the conversion efficiencies as high as 17.05 %. Low cost and high efficiency silicon solar cells fabrication sequence has also been explained in this paper.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.6
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• pp.526-534
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• 2022

The modular multilevel converter (MMC) has been widely applied to various industrial areas because of its various advantages and structural characteristics. Therefore, many methods for synthesizing the output voltage of MMC have been studied. Among these methods, phase-shifted pulse width modulation (PSPWM) is frequently used in MMC systems because it has diverse merits, such as excellent output qualities even with a small number of cells and uniform power distribution among cells. In this study, the total harmonic distortion (THD) of the output voltage is analyzed in accordance with the number of cells in one arm of a single-delta bridge cell MMC in order to compare PSPWM methods in terms of the THD of the output voltage. The physical characteristics of the triangle and sawtooth carrier waves used for the PSPWM and the mathematical modeling of output voltage are introduced. Then, the obtained results are verified through real-time simulation of a 1 MW single-delta bridge cell MMC system.

• Journal of Industrial Technology
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• v.20 no.A
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• pp.229-238
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• 2000

Simulation analysis for an auto body manufacturing system has been performed in this study. The major goal is to figure out the condition yielding the production rate, 70 per hour. It is, however, very difficult to maintain this rate due to inherent system factors such as machine failure rates, machine repair rates, number of carriers between manufacturing lines(shops), carrier speed etc. We first carefully examined the system and developed a simulation model using ARENA. We then applied statistical experimental design concepts for performance analysis. Our results indicate that the buffer size of 30 and quick repair of failed robots are required for the desired production rate. Other factors, on the other hand, are seen to have minor effects on the throughput. The approach taken in this study and the results obtained may provide a practical guideline for performance analysis and thus be applied without trepidation for similar cases.

• Journal of Korean Institute of Industrial Engineers
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• v.17 no.1
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• pp.109-115
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• 1991

In automated manufacturing systems, Automated Guided Vehicle(AGV) Systems are increasingly important in material handling and manufacturing operations. A considerably flexible AGV system needs to be operated with maximum effectiveness. This paper develops an algorithm for the determination of the entering point and the number of AGVs required in the Flow Shop Type FMS. We consider an AGV used as a carrier and mobile workstation. For the limited number of AGV, the entering point of an AGV on a simple loop is determined in order to maximize the utilization of AGVs. For the unlimited number of AGVs, the number of AGVs required in the FMS is determined on the basis of the entering point of AGVs. The result by the algorithm may be used as a criterion on the control of material flow and the assignment of AGVs in the FMS. A numerical example is given to illustrate the algorithm.

• Proceedings of the Korean Society for Quality Management Conference
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• 2010.04a
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• pp.161-167
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• 2010

Recently, the number of input method by Smart-Phone increasing in handheld digital product released. According to the development of telecommunication speed of middle carrier, demand for the multimedia contents is high so, it demands that the display of smart-phone shall be large. It is expected that the market share of smart-phone will be constantly getting bigger. For the robust changes, related study is not done too much for smart-phone. As the market of smart-phone, it is expected that the necessity of relevant study is salient issue.

• Journal of Industrial Technology
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• v.29 no.B
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• pp.101-105
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• 2009

A 1.571GHz LC VCO with optimized spiral inductor for GPS receiver is designed in 130nm CMOS process. The phase noise of the VCO has been reduced the use of high Q inductor and on chip filter. It has phase noise of -91dBc/Hz, -111dBc/Hz, and -131dBc/Hz at 10kHz, 100kHz, and 1MHz offset frequencies from the carrier, respectively. This VCO consumes 2mA from a 0.6V supply.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.32
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• pp.1-6
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• 1994

Many vehicle routing methods have been suggested, which minimize the routing distances of vehicles to reduce the total transportation cost. In describing a distribution network, we have stated that it is basically a system or a set of locations that, receive or store material plus the routes that connect these locations. Whether the network is spread over some geographic region or is whitin a single facility, the definition remains the same. Implicit in this definition, however, is that both the locations and the transportation between these locations must be considered in any decisions regarding the design of the operation of the overall network. The purpose of this paper is optimal layout using transportation quantity and distance in the total system operation. And we minimize the sum of load-carrier costs and spur costs in this flow network.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1164-1169
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• 2009

In this study, the bracket for car was designed in 3D using Cimatron Die Design, one of the automatic modules. To facilitate the stamping of the product, the layout of the strip was adjusted slightly. The blank layout of the double-width, 2-line, 2-pull out inner carrier was then optimized as a single arrangement. 3D design was completed in 11 processes.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.1
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• pp.1-7
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• 2014

We consider a human contact social network that has connections through cellphone addresses. To construct such a social network, we use real call records provided by a large carrier, and connect to each other if there exists a call record between any two cellphone users. Due to its huge amount of data, we down-sample it in a way that the smallest-degree nodes are removed, in turn, from the network. For a moderate size of the networks we show that the degree distribution of the network follows a power-law distribution via linear regression analysis, implying the so-called scale-free property. We finally suggest some alternative measures to analyze a social network.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.326-332
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• 2018

In this study,the result shows that polyvinyl alcohol-sodium alginate (PVA-SA) gel bead crosslinked with sodium sulfate are better among the different methods by comparing the relative mechanical strength, mechanical strength swelling and expansion coefficient of beads in water. Subsequently, anammox biomass entrapment by PVA-SA gel was introduced into continuous stirred tank reactor (CSTR). After 24 operation days, the nitrogen removal efficiency achieved 60%, while the nitrogen loading rate (NLR) was $0.14kgN/m^3/d$ and the experiment data indicated that PVA-SA gel bead crosslinked with sodium sulfate can be used to initiate anammox process. Furthermore, it is an alternative for culturing anammox in a long-term operation.