• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.2
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• pp.73-77
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• 2004

The color enhancement for natural Zambian amethyst of low quality was carried out by the hydrothermal treatment method. The hydrothermal treatment conditions were as follows: reaction temperature; $300^{\circ}C$, duration; 30 hrs, filling; 40%, solvent; 6 M-HCI solution. The reddish purple amethyst of high quality was obtained under these conditions. From the result of ICP/AES, it was known that color enhancement was affected by a Fe elemental content to exist in the inside of natural Zambian amethyst. Also, from the result of UY-VIS-NIR, it was shown that the absorption peak at 550 nm after hydrothermal treatment is slightly lower than those of non-treated natural Zambian amethyst. In this study, it was known that hydrothermal treatment method was a way to suitable for increase of commercial value of natural Zambian amethyst.

• 전자공학회논문지 IE
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• v.45 no.3
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• pp.5-12
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• 2008

We propose efficient scan testing method capable of reducing the test data and power dissipation for digital logic circuits. The proposed testing method is based on a hybrid run-length encoding which reduces test data storage on the tester. We also introduce modified Bus-invert coding method and scan cell design in scan cell reordering, thus providing increased power saving in scan in operation. Experimental results for ISCAS'89 benchmark circuits show that average power of 96.7% and peak power of 84% are reduced on the average without fault coverage degrading. We have obtained a high reduction of 78.2% on the test data compared the existing compression methods.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1303-1312
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• 2008

Satellite WiBro system has high PAPR characteristics in addition to the nonlinear characteristics of the power amplifier. These characteristics reduce amplifying efficiency of the power amplifier and also cause high error rate and interference with adjacent channels. This paper proposed satellite WiBro based system to reduce input signal's IBO of TWTA remarkably by adapting simultaneously PAPR reduction techniques, active-constellation extension technique and pre-distortion technique.

• The Korean Journal of Rheology
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• v.9 no.4
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• pp.163-173
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• 1997

Polystyrene/polycarbonate 조성이 약 50/50인 3종류의 Poly(carbonate-g-styrene) 공중합체의 동적 탄성율, E*($\omega$)와 동적 스트레인-광학계수 O*($\omega$)을 유리전이 영역부근의 여러온도에서 동시에 측정하여 연구하였다. 두 개의 공중합체는 각각의 스티렌 그라프트쇄 에 5, 10 wt%의 MAH를 함유하고 있다. 이들 공중합체의 E*($\omega$)와 O*($\omega$)완화거동과 그라 프트 공중합체의 상용성과 연관하여 비교 고찰하였다. 공중합체들의 E*($\omega$)는 전형적인 무 정형 고분자의 유리전이 완하거동을 보였으며 정성적인 차이를 발견할수 없었다. 그러나 고 강도의 단일 tan$\delta$분산의 저주파수 영역에 미세분산을 나타내, 공중합체는 2상으로 분리되 어 있음이 추정되엇다. 폴리스티렌 그라프트체에 무수 말레인산 함유량이 증가함에 따라, 저 주파수 영역의 미세피크가 $\alpha$주분산에 병합되어 성분 고분자간의 상호 형동성이 증가함을 알수 있었다. 3공중합체의 유사한 기계적 특성과는 달리, 광학적 완화 스펙트럼 O*($\omega$)는 정 성적으로 명확한 차이를 보여 공중합체들의 광학완화 거동이 명확히 다름을 나타냈다. 기계 적 특성보다는 광학적 특성이 공중합체내의 성분 고분자의 미세한 완하 거동에 훨씬 민감한 응답을나타냈다. 이러한 특성적인 공중합체의 O*($\omega$)차이를 공중합체의 조성단일 고분자 PS, PC의 O*($\omega$)의 가성성을 가정하여 모사하였다 모사에서 구한 광학적 부분 기여 파라메 터를 사용하여 공중합체의 상용성을 고찰하였다.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.1
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• pp.53-59
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• 2004

In case of load forcasting the most important problem is to deal with the load of special days. According this paper presents forecasting method for speaial days peak load by neural networks model. by means of neural networks mothod using the historical past special- days load data, special-days load was directly forecasted, and forecasting % error showed good result as 1∼2% except vacation season in summer Consequently, it is capable of directly special days load, With the models, precision of forecasting was brought satisfactory result. When neural networks was compared with the orthogonal polynomials models at a view of the results of special-days load forecasting, neural networks model which used pattern conversion ratio was more effective on forecasting for special-days load. On the other hand, in case of short special-days load forecasting, both were valid.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.1
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• pp.71-78
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• 2016

This paper proposes the new electric power demand forecast model which is based on an artificial neural network and considers time and weather factors. Time factors are selected by measuring the autocorrelation coefficients of load demand in summer and winter seasons. Weather factors are selected by using Pearson correlation coefficient The important weather factors are temperature and dew point because the correlation coefficients between these factors and load demand are much higher than those of the other factors such as humidities, air pressures and wind speeds. The experimental results show that the proposed model using time and seasonal weather factors improves the load demand forecasts to a great extent.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.165-166
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• 2015

Due to the international economic downturn and the increasing competition, container terminals have been trying to achieve cost effectiveness and high service levels. Shipping companies want to get better services from container terminals but container terminals only have limited space and equipment. Frequently, too many external trucks come to the terminal at the same time, and create bottle necks at the terminals. Ouside the container terminals traffic jams occur as well. As a result, stakeholders need a vehicle booking system. By VBS, container terminals can plan efficiently in advance to avoid work delay and the truck drivers can finish their jobs quickly. This paper aims to search efficient models for the container terminals by using VBS.

• Journal of Adhesion and Interface
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• v.12 no.1
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• pp.1-10
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• 2011

An automated reaction calorimeter was used to directly monitor the rate of emulsion polymerization of vinyl acetate using poly(vinyl alcohol) (PVAs) having different degrees of blockiness. By using this technique in conjunction with other off-line measurements of the evolution of particle size distributions, important details of the process were observed. No constant graft rate period was observed for both low and high initial monomer-water ratios. The gel effect was observed for the low monomer-water ratio recipe. The particle size distributions were broad (particle diameter 40~100 nm) and bimodal. Continuous nucleation was observed to be accompanied by 'limited aggregation' and flocculation during the particle growth stages. It was speculated to be due to the occurrence of the extensive 'limited aggregation' and chain transfer to PVA leading to grafting.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.296-297
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• 2007

PMN-PZT 단층 및 다층 후막을 알루미나 기판위에 켄티레버 형태로 제작하여, 외부의 미소 진동에 의한 마이크로 발전 특성을 고찰하였다. 미소 변위에 의한 마이크로 발전 특성은 켄티레버의 무게(load), 진동수, 켄티레버의 길이 등에 밀접한 영향을 미치므로 이에 준한 요소를 고려하여 여러 가지 변수로 실험하였다. 연구 결과 서로 다른 소재의 기판과 발전체의 계면 분리 현상, 전극과 발전체의 분리 현상, 소결 온도 등이 소재 측면의 문제점으로 크게 대두되었으며, $5{\times}20mm$ 기판위에 형성된 발전체의 특성은 $1.1k{\Omega}{\sim}1M{\Omega}$의 부하에 따른 전압변동이 0.01V에서 3.6V로 큰 차이가 났다. 켄티레버의 로드의 변화에 대한 피크 전압은 $1.9{\sim}{\pm}2.8V$로 조사되었으며, 출력은 $0.45{\sim}4{\mu}W$로 측정되었다. 그러나 이런 외부 조건 보다 압전체의 공진 특성과 진동수는 가장 중요한 요인으로 나타났으며, 몇몇 문제가 해결될 경우 마이크로 발전소자로의 활용 가능성이 있는 것으로 조사되었다.

• Polymer(Korea)
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• v.35 no.3
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• pp.272-276
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• 2011

The induction mechanisms of planar arrangements in cholesteric liquid crystals (CLC) which showed selective reflections of visible light were investigated by measuring the selective reflectivity and FTIR peak intensity of $C{\equiv}N$ stretching band. Although the planar arrangement of CLC was not as perfectly induced as the cases prepared with using alignment layers, it could be also induced by stretching polymer substrate or by applying shear forces. The planar arrangements were induced by forming CLC helical structures on top of liquid crystal molecules which were in contact with the substrate and oriented all in the same direction.