• 한국정보통신학회논문지
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• 제24권2호
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• pp.325-328
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• 2020

This paper demonstrated a voltage-controlled oscillator (VCO) using cost-effective (1-poly 6-metal) mixed signal standard CMOS process. To have the high-quality factor inductor in LC resonator with thin metal thickness, patterned-ground shields (PGS) was adopted under the spiral to effectively reduce the ac current of low resistive Si substrate. And, because of thin top-metal compared with that of RF option (2 ㎛), we make electrically connect between the top metal (M6) and the next metal (M5) by great number of via array along the metal traces. The circuit operated from 2.48 GHz to 2.62 GHz tuned by accumulation-mode varactor device. And the measured phase noise of LC VCO has -123.7 dBc/Hz at 1MHz offset at 2.62 GHz and the dc-power consumption shows 2.07 mW with 1.8V supply voltage, respectively.

• 전기학회논문지P
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• 제58권2호
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• pp.207-213
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• 2009

Electrolytic capacitors have been widely used in power electronics system because of the features of large capacitance, small size, high-voltage, and low-cost. Electrolytic capacitors, which is most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. Therefore it is important to estimate the parameter of an electrolytic capacitor to predict the failure. This paper proposed a novel fault diagnosis method of an electrolytic capacitor used for voltage smoothing in boost DC converter. The equivalent series resistance(ESR) of electrolytic capacitor estimated from FFT result of filtered waveform of capacitor voltage/current. Main advantage of the proposed method include circuit simplicity and easy implementation. Simulation and experimental results are shown to verify the performance of the proposed method.

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권3호
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• pp.136-145
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• 2006

Two major processing technologies of GaAs HBT and pHEMT have been released in production at Win Semiconductors corp. to address the strong demands of power amplifiers and switches for both handset and WLAN communications markets. Excellent performance with low processing cost and die shrinkage features is reported from the manufactured MMICs. With the stringent tighter manufacturing quality control WIN has successfully become one of the major pure open foundry house to serve the communication industries. The advancing of both technologies to include E/D-pHEMTs and BiHEMTs likes for multifunctional integration of PA, LNA, switch and logics is also highlighted.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.140-143
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• 2001

Digital shearography, a speckle pattern method is based on the superposition of two laterally sheared images. Therefore, object points which are positioned in some distance from each other are superposed in the image plane. This shearography, one of NDT methods without contact, is able to inspect defects in pipelines and pressure vessels that are used in nuclear power plants. This is can inspect whole fields and has a low sensitivity to environmental noise. Because optical setting is very simple, it has a little exhaustion of time, cost and man power. And also it can find a defect position through real time monitoring of a part. This paper, finds out the relationship among shearing quantity image quality and defect size with this method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.105-107
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• 2018

This paper presents a new hybrid multilevel converter topology, which consists of a combination of the series connected switched capacitor units with boost ability, and an H-bridge with T-type bidirectional switches. The proposed converter boosts the input voltage without any bulky inductors, and has the small number of components, which can make the size and cost of a power converter greatly reduced. The output filter size and harmonics are also reduced by the high quality multilevel output. In addition, there is no need for complicated methods to balance the capacitor voltage. Simulation and experimental results with a nine-level converter system are presented to validate the proposed topology and modulation method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.120-122
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• 2007

A new power quality disturbance generator is proposed. The proposed scheme overcomes the problem of voltage drop of the conventional generator in normal mode. Therefore, the output voltage of the proposed generator is constant in normal mode and the efficiency of the series transformer is improved. The proposed generator has good feature of simple structure, cost effective implementation, high reliability and easy control. The usefulness of the scheme is verified through simulation and experiments.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.547-553
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• 2024

Hydrogen is considered a key energy source to achieve carbon neutrality through the global goal of 'Net Zero'. Due to limitations in domestic green hydrogen production, Korean companies are interested in importing green hydrogen produced overseas. Because Australia and the Middle East possess high-quality renewable energy resources, they are attracting attention as suitable regions for producing green hydrogen using renewable energy. The cost of constructing and operating a green ammonia plant varies depending on the region. In this study, an economic feasibility comparison of green ammonia plant construction in Australia and the Middle East is conducted. Through this, it is expected to contribute to the economic analysis and feasibility analysis of the project to import hydrogen in the form of green ammonia into Korea.

• 한국환경과학회지
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• 제13권2호
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• pp.143-148
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• 2004

In this paper, the properties of inter - locking block using fly ash are discussed in order to provide economical advantages and improve quality, and protect environment and recycle resources. Fly ash is the by-product of coal in thermal power plant. The experimental parameters are fly ash content, the amount of AE water - reducing agent and mixing proportion of cement mortar. According to the experimental results, the improvement of quality in the side of strength, absorption ratio and freeze - thaw resistance for manufacturing inter -locking block and the curtailment of cost can be achieved in case of 15% of fly ash and 0.3% of AE water- reducing agent are mixed into mortar mixture of 1 :6(C:S).

• 소음진동
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• 제7권4호
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• pp.689-700
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• 1997

There are many difficulties in designing the engine structure properly due to the strong conflicts between NVH characteristics and the high performance, light weight and low product cost. Many feasible noise reduction techniques should be carefully incorporated to meet such stringent noise requirements. It is also required that the engine development be carried out by introducing concurrent engineering, in which the analysis and test database are usefully applied to the detail designs from the 1st stage. This paper reviews the significance of the noise characteristics of the structure elements in relation to the combustion pressure. The mechanisms of the crank shaft rumbling, which is the main source having the bad influence on the sound quality, are also explained. The influences of dynamic behavior of engine structure on its noise are investigated, followed by discussions on experimental results of the features necessary for the design of low noise engine concepts.

• 한국대기환경학회지
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• 제2권1호
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• pp.103-110
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• 1986

Since sulfur dioxide is released from the oxidation of sulfur in fuel, the level of $SO_2$ in industrial areas can be effectively managed by optimizing the allocation of fuels: the fuel should be allocated to each industries so as to achieve the air quality goal in the area with minimum fuel cost. The solution for this can be by solved using linear programming technique incorporated with the Gaussian dispersion equation. When this method was applied in Ulsan Industrial Complex, 39.3% of fuel expense could be saved compared with the present uniform fuel policy. With this method, bituminous coal generally was allocated to big emission sources such as power plants or to industries sparsely located in remote areas, and LPG or low-sulfur oils to small or medium-size sources in dense indurstrial aras. However, the particulates emission will increase with this policy, because it maximizes the use of coal within the limit to achieve the air quality goal in the area.