• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.602-602
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• 2013

산화아연(ZnO)은 직접 천이 와이드 밴드갭(3.37 eV)과 큰 excitation binding energy (60 meV)를 갖는 II-VI 반도체로 광촉매, light emitting diodes (LED), dye-sensitized solar cell 등의 여러 가지 분야에서 각광받고 있는 물질이다. ZnO는 열역학적으로 안정한 polar terminated (001)면과 nonpolar low-symmetry (100)면을 갖으며 (100)면이 (001)면보다 더 안정하기 때문에 (100)방향의 일차원구조가 쉽게 합성된다. 이러한 일차원 구조는 빛의 산란을 유도하여 더 많은 빛의 흡수를 야기 시킬 뿐만 아니라 일차원 구조를 따라 효율적인 전하 전달을 가능하게 한다. 본 연구에서는 일차원 구조의 장점을 살리면서 더 넓은 표면적을 갖는 hierarchical ZnO nanowire 구조를 수열합성법과 스퍼터링증착법을 이용하여 합성하였다. Hierarchical ZnO nanowire는 SEM, TEM을 이용하여 구조를 관찰하였고 UV-visable spectroscopy를 이용하여 일차원 구조의 ZnO nanowire와의 absorbance, transmittace 차이를 확인하였다.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.1
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• pp.35-45
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• 2017

In order to improve the anaerobic digestion efficiency of the sewage sludge, the methane potential of the hydrolysate generated from the hydro-thermal reaction at 170, 180, 190, 200, 210, $220^{\circ}C$ was analyzed and the constitutional characteristics of the organic materials were estimated by dividing organic materials of hydro-thermal hydrolysate into easily biodegradable, decomposition resistant, and non-biodegradable organic materials applying the parallel first order kinetics model. The ultimate methane potential of sewage sludge hydro-thermal hydrolysate increased to 0.39, 0.39, 0.40, 0.44, 0.45, and $0.46Nm^3/kg-VS_{added}$ as hydro-thermal reaction temperature increased from 170, 180, 190, 200, 210, $220^{\circ}C$. It has been shown that the organic matter of sewage sludge is solubilized to increase the content of biodegradable organic material($VS_B$). The easily degradable organic matter($VS_e$) content was highest at hydro-thermal reaction temperature of 200 and $210^{\circ}C$, and optimum hydro-thermal reaction temperature for organic matter solubilization of sewage sludge was in the range of $200{\sim}210^{\circ}C$. In addition, the amount of biodegradable organic material($VS_B$) and easily biodegradable organic matter ($VS_e$) in the hydrolysate of sewage sludge was the highest at hydro-thermal reaction temperature of $200^{\circ}C$.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.21-25
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• 1997

우수한 세라믹스 제조를 위해서는 작은 입자지름, 좁은 입도분포, 구형의 입자형태, dopant와 matrix가 균일한 고용체를 갖고, 응집입자가 없으며 고순도인 원료 분말의 제조가 선행되어야 한다. 이를 위하여 본 연구에서는 수열 합성법을 이용하여$\alpha$-Al$_2$O$_3$, $\alpha$-SiO$_2$, PZT, PSZT, BTO등의 미세분말을 제조하는 공정에서 반응온도, 광화제의 양과 종류, 반응시간, 출발물질의 양과 종류, 전처리공정, 교반공정 등이 평균입자지름과 결정성 및 입도분포에 미치는 영향을 조사하였다. 그결과 미세분말의 종류에 관계없이 반응온도, 반응시간, 성장기질의 농도, 종자결정의 농도 등이 증가할수록 평균입경은 커지며, 광화제의 농도가 증가할수록 평균 입자지름이 작아지고, 광화제의 농도가 종자결정의 농도가 증가할수록 입도분포가 좁아짐을 알 수 있었다. 특히 $\alpha$-SiO$_2$에 대해 수열합성실험으로부터 평균입자지름과 수열합성의 조업변수간의 특성방정식을 얻었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8C
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• pp.735-741
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• 2005

In this paper, we derived the autocorrelation distributions, i.e., the values and the number of occurrences of each value of the autocorrelation function of Sidel'nikov sequences. The frequency of each autocorrelation value of an M-ary Sidel'nikov sequence is expressed in terms of the cyclotomic numbers of order M. It is also pointed out that the total number of distinct autocorrelation values is dependent not oかy on M but also on the sequence, but always less than or equal to ($\frac{M}{2}$)+1.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.07a
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• pp.307-311
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• 2003

Okeya-Sakurai는［12］에서 단순한 형태의 랜덤한 덧셈-뺄셈 체인의 대응방법［14］은 SPA공격에 취약함을 보였다. 그러나 그들의 분석 방법은 복잡한 형태［14］에는 적용되지 않는다. 본 논문에서는 Okeya-Sakurai의 공격 알고리듬에 두 가지 잠재된 문제가 있음을 보인다. 또한［12,15］와는 다른 강하고 견고한 새로운 공격 알고리듬을 제안한다. 본 논문에서 제안하는 공격 알고리듬을 사용하면 복잡한 형태의 랜덤한 덧셈-뺄셈 체인［14］또한 완벽하게 분석된다. 본 논문의 결과를 표준에서 제안된 163비트로 실험한 결과 단순한 형태에서는 20개의 AD수열로 대략 94%의 확률로 공격이 성공하며 30개의 AD수열로는 대략 99%의 확률로 공격이 성공한다. 또한, 복잡한 형태에서는 40개의 AD수열로 94%의 확률로 70개의 AD수열로는 99%로의 확률로 공격이 성공한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.6
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• pp.42-48
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• 2010

Joint Tactical Information Distribution System (JTIDS) uses cyclic code shift keying (CCSK) for baseband symbol modulation, in which 5-bit information is mapped to one of thirty two 32-chip sequences. It is a kind of direct sequence based spread spectrum communication. In this paper, the performance of non-coherent detection of CCSK using non-orthogonal 32-chip sequence is evaluated. And a 32-chip sequence with better performance is also proposed and compared with the conventional one.

• Journal of the Society of Disaster Information
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• v.16 no.2
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• pp.383-391
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• 2020

Purpose: To identify internal self ignition and ignition caused by external flames in energy storage rooms, and to analyze the difference between ignition due to overheating and ignition caused by external heat sources. Method: membrane melting point measurement, battery external hydrothermal experiment, battery overcharge experiment, comparative analysis of electrode plate during combustion by overcharge and external heat, overcharge combustion characteristics, external hydrothermal fire combustion characteristics, 3.4 (electrode plate comparison) / 3.5 (overcharge) /3.6 (external sequence) analysis experiment. Result: Since the temperature difference was very different depending on the position of the sensor until the fire occurred, it is judged that two temperature sensors per module are not enough to prevent the fire through temperature control in advance. Conclusion: The short circuit acts as an ignition source and ignites the mixed gas, causing a gas explosion. The electrode breaks finely due to the explosion pressure, and the powder-like lithium oxide is sparked like a firecracker by the flame reaction.

• The Journal of the Korea Contents Association
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• v.5 no.6
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• pp.343-350
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• 2005

During the design of a successful digital watermarking systems, Pseudo-Noise(PN) sequences are widely used to modulate information bits into watermark signals. In this method, the number of bits that can be hidden within a small image by means of frequency domain watermarking is limited. In this paper, we show the possibility of introducing chaotic sequences into digital watermarking systems as potential substitutes to commonly used PN-sequences. And we propose a method that transforms the text to chaotic sequence. In our current implementation, we show how the sample text is expressed by an implied unit data(watermark) and the implied unit data is regenerated into the original left. Because we use this implied data as watermark for information hiding, we can insert much more watermark compared with previous method.

• Korea Journal of Geothermal Energy
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• v.5 no.2
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• pp.17-23
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• 2009

• Korea Journal of Geothermal Energy
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• v.7 no.1
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• pp.43-50
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• 2011