• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권7호
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• pp.329-333
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• 2001

The pulsed poser system has been widely used to many applications, such as E/P(Electrostatic Precipitator), DeNox/DeSOx power system, ozon generator, etc. A pulse energy efficiency for load depends on the rising time, peak value, pulse duration and impedance matching, etc. The pulse generator generally required for short pusle duration and high peak value was forced to consider its volume and economy. In this study, developing a compact pulse generator that applied for cascading method to be made of two pulse transformers, we compared cascading voltage with non cascading one by applying the pulse energy to load. Adopting cascading technique to pulse transformer, we found that average cascading voltage was about 60[%] of theoretical value. Maximum cascading ratio was calculated at 60 times compared with non cascading voltage.

• 한국컴퓨터산업학회논문지
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• 제2권3호
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• pp.363-368
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• 2001

이동통신(Mobile Telecommunication), X선 발생장치, 오존발생기, 레이저시스템 등에 사용되는 임펄스의 지속시간(pulse duration)은 충분히 짧고 빠른 상승률을 갖는 임펄스 전압을 발생시킬 수 있는 펄스발생장치(Pulse Generator)가 필요하다. 펄스발생장치 설계시 회로정수, 전력용 스위치는 임펄스 특성을 직접적으로 결정하게 된다. 펄스발생장치는 출력에너지가 순간적으로 부하에 전달될 때 최소의 손실로 전류지속시간 동안 안정성을 갖고 전류차단시 소호특성이 우수한 전력용 스위치가 요구된다. 펄스에너지 효율은 펄스 상승시간(rising time), 첨두치(peak value), 지속시간(pulse duration), 부하와의 임피던스 매칭(impedance matching) 등에 따라 민감하게 반응한다. 또한, 짧은 펄스지속시간과 높은 첨두치의 펄스에너지를 얻기 위해서는 펄스발생장치의 크기 및 경제성을 고려하지 않을 수 없다. 본 연구에서는 수$\mu$s의 펄스지속시간(pulse duration), 수 l00ns의 상승시간(rising time) 및 수 10kV의 첨두값(peak value), 수 10~100회의 반복율 갖는 안정적인 임펄스 형성을 위해 소형 펄스트랜스 2개를 조합한 cascading 방식을 적용하여 컴팩트(compact)한 펄스발생장치(pulse generator)를 구성하여 부하에 직접 제작한 임펄스를 인가한 결과 우수한 효과를 거둘 수 있었고, 그 적용에 대한 연구는 차후에 진행하고자 한다.

• 전자공학회논문지D
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• 제36D권7호
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• pp.66-79
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• 1999

본 논문에서는 얕은 양자 우물(extremely shaliow quantum wells, ESQWs)을 사용한 광 쌍안정 대칭형 자기 전광 소자(symmetric self elctrooptic effect device, S-SEED)의 성능에 있어서 높은 입사 광전력의 영향을 조사한다 . 다음과 같은 네 가지 ESQWs S-SEED 구조를 고려하였다. 무 반사 입힘(AR-coated) ESQWs S-SEED, back-to-back ARcoated ESQWs S-SEED, 비대칭 공명구조(AFP) ESQWs S-SEED, back-toback AFP ESQWs S-SEED. 입사 광 전력이 증가함에 따라 On/Off 대조비, On/Off 반사율 차이와 같은 소자성능은 ohmic heating 과 여기자 포화(exciton saturation)의 영향으로 심각하지 않게 저하된다. 한편 소자의 스위칭 속도는 지속적으로 증가하다가 특정 입사 광 전력 하에서 점차 감소하기 시작한다. 직렬 광 연결 시스템(cascading optical interconnection system)에 있어서 소자의 최대 속도 스위칭 동작을 위한 최대 입사 광 전력의 최적화를 바탕으로 0 V와 5 V의 외부 전압 조건에서 양자우물의 수를 변화시키면서 $5{\times}5{\mu}m^2$의 mesa 영역에 대하여 네 가지 ESQWs S-SEED의 시스템 비트 레이트를 모의 실험하고 그 결과를 분석하였다.

• 대한안전경영과학회지
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• 제16권3호
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• pp.451-469
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• 2014

The purpose of this study is to implement and develop the integrated Economic Value Added (EVA) and Time-Driven Activity-Based Costing (TDABC) model to seek both improvement of Net Operating Profit Less Adjusted Tax (NOPLAT) and reduction of Capital Charge (CC). Net Operating Profit Less Adjusted Tax (NOPLAT) can be maximized by reducing the indirect cost of an unused resource capacity increased by Cost Capacity Ratio (CCR) of TDABC. On the other hand, Capital Charge (CC) can be minimized by improving the efficiency of Invested Capital (IC) considered by Weighted Average Cost of Capital (WACC) of EVA. In addition, the integrated system of TDABC using Balance Scorecard (BSC) and EVA is developed by linking between the lagging indicators and the three leading indicators. The three leading indicators include customer, internal process and growth and learning perspectives whereas the lagging indicator includes NOPLAT and CC in terms of financial perspective. When the Critical Success Factor (CSF) of BSC is cascading as a cause and an effect relationship, time driver of TDABC and capital driver of EVA can be used efficiently as Key Performance Indicator (KPI) of BSC. For a better understanding of the proposed EVA/TDABC model and BSC/EVA/TDABC model, numerical examples are derived from this paper. From the proposed model, the time driver of TDABC and the capital driver of EVA are known to lessen indirect cost from comprehensive income statement when increasing the efficiency of operating IC from the statement of financial position with unified KPI cascading of aligned BSC CSFs.

• 한국멀티미디어학회논문지
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• 제20권1호
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• pp.17-31
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• 2017

The aim of the paper is to present an object recognition method toward augmented reality system that utilizes existing education instruments that was designed without any consideration on image processing and recognition. The light reflection, sizes, shapes, and color range of the existing target education instruments are major hurdles to our object recognition. In addition, the real-time performance requirements on embedded devices and user experience constraints for children users are quite challenging issues to be solved for our image processing and object recognition approach. In order to meet these requirements we employed a method cascading light-weight weak classification methods that are complimentary each other to make a resultant complicated and highly accurate object classifier toward practically reasonable precision ratio. We implemented the proposed method and tested the performance by video with more than 11,700 frames of actual playing scenario. The experimental result showed 0.54% miss ratio and 1.35% false hit ratio.

• ETRI Journal
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• 제28권5호
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• pp.664-667
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• 2006

We propose an efficient audio transcoding algorithm that can convert audio streams from terrestrial digital television broadcasting service stations to those for terrestrial digital multimedia broadcasting hand-held receivers. The proposed algorithm avoids the complicated psychoacoustic analysis by calculating the scalefactors of the bit-sliced arithmetic coding encoder directly from the signal-to-noise ratio parameters of the AC-3 decoder. The bit-allocation process is also simplified by cascading the nested distortion control loop. Through subjective evaluation, it is shown that the proposed algorithm provides comparable audio quality to tandem coding but it requires much smaller complexity.

• 한국분말재료학회지
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• 제10권6호
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• pp.415-421
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• 2003

The study for producing the flake powders by milling of aluminum foil and gas atomized powders was carried out. The effects of lifter bars on the ball motions and milling of aluminum foils were also investigated. The aluminum foils were laminated each other, elongated, fragmented into small foils and finally formed into the flake powders during the dry ball-milling. The spherical atomized-powders were milled to coarse flake powders with high aspect ratio and then changed to fine flake powders with lower aspect ratio. Even though long times were required for making flake powders by milling of foils, the water covering areas of them were higher than those of powders milled using gas-atomized powders, suggesting aluminum foils were more plastically deformed by micro-forging. On the other hand, as the number of lifter bars increased, the necessary rotation speeds of milling jar for cascading mode and cataracting mode decreased drastically. It was possible to achieve same quality of milled flake powder by using the lifter bars under the lower milling speeds. The painting test showed that the appearance of painted surface was good and optimum content range of aluminum paste in car paint to maximize the degree of gloss was 3-5%.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.179-184
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• 2006

Rapid and high-precision positioning with a Global Navigation Satellite System (GNSS) is feasible only when very precise carrier-phase observations can be used. There are two kinds of mathematical models for ambiguity resolution. The first one is based on both pseudorange and carrier phase measurements, and the observation equations are of full rank. The second one is only based on carrier phase measurement, which is a rank-defect model. Though the former is more commonly used, the latter has its own advantage, that is, ambiguity resolution will be freed from the effects of pseudorange multipath. Galileo will be operational. One of the important differences between Galileo and current GPS is that Galileo will provide signals in four frequency bands. With more carrier-phase data available, frequency combinations with long equivalent wavelength can be formed, so Galileo will provide more opportunities for fast and reliable ambiguity resolution than current GPS. This paper tries to investigate phase only fast ambiguity resolution performance with four Galileo frequencies for short baseline. Cascading Ambiguity Resolution (CAR) method with selected optimal frequency combinations and LAMBDA method are used and compared. To validate the resolution, two tests are used and compared. The first one is a ratio test. The second one is lower bound success-rate test. The simulation test results show that, with LAMBDA method, whether with ratio test or lower bound success rate validation criteria, ambiguity can be fixed in several seconds, 8 seconds at most even when 1 sigma of carrier phase noise is 12 mm. While with CAR method, at least about half minute is required even when 1 sigma of carrier phase noise is 3 mm. It shows that LAMBDA method performs obviously better than CAR method.

• 대한전자공학회논문지SD
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• 제37권5호
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• pp.23-30
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• 2000

지수함수형태의 전달함수를 갖는 전계흡수 광변조기(electroabsorption modulator： EAM)의 비선형성 보상을 위해 로그함수형태의 전달함수를 갖는 반도체 광증폭기(semiconductor optical amplifier : SOA)를 이용한다. 우선 SOA의 전달함수는 EAM의 전달함수와 역함수 관계를 갖기 때문에 EAM의 상호변조왜곡 (intermodulation distortion： IMD)을 보상한다. 더불어 SOA가 제공하는 이득에 의해 변조신호는 증폭되어진다. 이 두 가지에 의해 EAM의 SFDR(spurious free dynamic range)은 증가한다. 이때 SOA는 EAM 뒷단에 직렬로 연결되어 이득포화영역에서 동작되어진다. EAM의 IMD 보상을 향상시키기 위해서는 SOA의 이득을 증가시켜 이득포화영역 기울기를 증가시켜야 한다. 하지만 SOA의 이득 증가에 따라 ASE 잡음도 증가하여 시스템의 잡음레벨을 높여 EAM의 SFDR은 감소한다. 즉 SOA의 이득포화영역 기울기와 ASE 잡음은 이득에 대해 trade-off를 가지게 되고 모의실험 결과 이득이 약 8㏈일 때 최적화 된다. 이 지점에서 EAM의 SFDR 향상은 약 9㏈였다. SOA를 사용한 EAM 선형성 향상 방법은 구성이 간편하고 3개의 소자를 집적할 경우 낮은 삽입손실, 낮은 편광의존성, 낮은 처핑 등 효율적인 아날로그 광변조기로 이용될 수 있다.