• 한국산학기술학회논문지
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• 제8권5호
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• pp.1069-1075
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• 2007

본 논문에서는 암/복호화의 동시수행, 가변되는 입력데이터들에 대한 라운드 횟수 결정, 별도의 키 생성알고리즘 없이 결정된 라운드 횟수에 대한 키 생성, 인증기능 등의 특징을 갖는 새로운 블록암호알고리즘인 BESA 암호화 알고리즘에 대한 연구를 수행하였다.

• 상하수도학회지
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• 제22권5호
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• pp.571-580
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• 2008

The influence of bacterial stress on anaerobic hydrogen-producing microorganisms was investigated in batch tests using serum bottles. Several physical and chemical stresses (i.e., heating, adding methane producing inhibitor and chemical acidification) were adapted as a pretreament of the seed sludge. In this experiment, the cultivation temperature were set at mesophilic ($35^{\circ}C$) and thermophilic conditions ($55^{\circ}C$) with adjusting pH at 5, 6, and 7 when using the mixture of food waste and activated sludge as a substrate. In conjunction with the pretreatment, hydrogen production was significantly enhanced as compared with that from untreated sludge. However, less biogas (hydrogen and methane) was produced without the pH control, resulted from the decrease of pH to below 4, mainly due to the formation of VFAs. Hydrogen and carbon dioxide gas were analyzed as main components of the biogas while methane not detected. With an application of chemical acidification, the highest hydrogen production value of 248 ml/l/day achieved at pH 7 and $35^{\circ}C$. In addition, more hydrogen gas produced when the ratio of butyric/acetic acid ratio increased. The optimum pH and temperature for hydrogen production were found to be 7 and $35^{\circ}C$, respectively.