• Interdisciplinary Bio Central
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• 제3권3호
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• pp.10.1-10.8
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• 2011

Introduction: Hash functions are computer algorithms that protect information and secure transactions. In response to the NIST's "International Call for Hash Function", we developed a biological hash function using the computing capabilities of bacteria. We designed a DNA-based XOR logic gate that allows bacterial colonies arranged in a series on an agar plate to perform hash function calculations. Results and Discussion: In order to provide each colony with adequate time to process inputs and perform XOR logic, we designed and successfully demonstrated a system for time-delayed bacterial growth. Our system is based on the diffusion of ${\ss}$-lactamase, resulting in destruction of ampicillin. Our DNA-based XOR logic gate design is based on the op-position of two promoters. Our results showed that $P_{lux}$ and $P_{OmpC}$ functioned as expected individually, but $P_{lux}$ did not behave as expected in the XOR construct. Our data showed that, contrary to literature reports, the $P_{lux}$ promoter is bidirectional. In the absence of the 3OC6 inducer, the LuxR activator can bind to the $P_{lux}$ promoter and induce backwards transcription. Conclusion and Prospects: Our system of time delayed bacterial growth allows for the successive processing of a bacterial hash function, and is expected to have utility in other synthetic biology applications. While testing our DNA-based XOR logic gate, we uncovered a novel function of $P_{lux}$. In the absence of autoinducer 3OC6, LuxR binds to $P_{lux}$ and activates backwards transcription. This result advances basic research and has important implications for the widespread use of the $P_{lux}$ promoter.

• Interdisciplinary Bio Central
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• 제4권3호
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• pp.10.1-10.12
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• 2012

Introduction: We investigated frameshift suppressor tRNAs previously reported to use five-base anticodon-codon interactions in order to provide a collection of frameshift suppressor tRNAs to the synthetic biology community and to develop modular frameshift suppressor logic devices for use in synthetic biology applications. Results and Discussion: We adapted eleven previously described frameshift suppressor tRNAs to the BioBrick cloning format, and built three genetic logic circuits to detect frameshift suppression. The three circuits employed three different mechanisms: direct frameshift suppression of reporter gene mutations, frameshift suppression leading to positive feedback via quorum sensing, and enzymatic amplification of frameshift suppression signals. In the course of testing frameshift suppressor logic, we uncovered unexpected behavior in the frameshift suppressor tRNAs. The results led us to posit a four-base binding hypothesis for the frameshift suppressor tRNA interactions with mRNA as an alternative to the published five-base binding model. Conclusion and Prospects: The published five-base anticodon/codon rule explained only 17 of the 58 frameshift suppression experiments we conducted. Our deduced four-base binding rule successfully explained 56 out of our 58 frameshift suppression results. In the process of applying biological knowledge about frameshift suppressor tRNAs to the engineering application of frameshift suppressor logic, we discovered new biological knowledge. This knowledge leads to a redesign of the original engineering application and encourages new ones. Our study reinforces the concept that synthetic biology is often a winding path from science to engineering and back again; scientific investigations spark engineering applications, the implementation of which suggests new scientific investigations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.12-14
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• 1997

The analysis of eigenvalue and eigenvector is a crucial procedure for many electromagnetic computation problems. However, eigenpair computation is timing-consuming task. Thus, its parallelization is required for designing large-scale and precision three-dimensional electromagnetic machines. In this paper, the Davidson method is parallelized on a cluster of workstations. Performance of the parallelization scheme is reported. This scheme is applied to a ridged waveguide design problem.

• 산업기술연구
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• 제17권
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• pp.255-260
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• 1997

The analysis of eigenvalue and eigenvector is a crucial procedure for many electromagnetic computation problems. Although it is always the case in practice that only selected eigenpairs are needed, computation of eigenpair still seems to be a time-consuming task. In order to compute the eigenpair more quickly, there are two resorts: one is to select a good algorithm with care and another is to use parallelization technique to improve the speed of the computing. In this paper, one of the best eigensolver, the Davidson method, is parallelized on a cluster of workstations. We apply this scheme to a ridged waveguide design problem and obtain promising linear speedup and scalability.

• 논리연구
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• 제9권2호
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• pp.99-116
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• 2006

There has been several proposals to resolve the gentle murder paradox; Forrester claims that the paradox shows that the deontic closure principle should be abandoned, while Sinnott-Armstrong claims that the paradoxical result arises from the scope ambiguity. However, I shall argue, the gentle murder paradox hinges on the logical structure of adverbial expressions. Although Davidson shows an insightful way of understanding logical structure of adverbs, there has been misunderstandings concerning the nature of his account. Especially what is called neo-Davidsonian event semantics is based upon combination of two fundamentally conflicting ideas. I shall propose a new way of understanding Davidson's account, on the basis of which I continue to give a new diagnosis of the gentle murder paradox.

• 논리연구
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• 제16권2호
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• pp.131-154
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• 2013

마이클 윌리엄스는 그의 논문에서 데이빗슨의 원초적 해석은 진리 조건적 의미 설명에 해당한다는 통설에 반대하면서, 해석에서는 실제로 팽 창적 진리가 설명적 역할을 수행하지 않으므로 해석은 진리 축소주의와 조화될 수 있다는 제안을 내놓는다. 본 논문을 통해 필자는 원초적 해석 내에서 진리와 의미 사이의 설명적 구도에 관한 올바른 이해를 모색하고, 이를 바탕으로 윌리엄스의 주장이 적절한가의 여부를 검토하고자 한다. 필자의 진단은 해석에 포함된 몇 가지 중심적인 요소들을 어떻게 바라볼 것인가에 따라서 윌리엄스의 대안적 해석 이론이 수용될 여지가 결정된다는 것이다. 특히 진리 조건에 대한 축소 또는 팽창적 이해는 원초적 해석을 이해하는 방식에서도 차이를 낳는 전제조건이며 그에 따라서 원초적 해석을 축소주의적으로 이해할 수 있는 가능성 도 결정됨을 본 논문은 논증할 것이다. 아울러 이와 비슷한 평가가 호위치의 사용 의미론과 데이빗슨 사이의 유사성을 주장하는 윌리엄스의 또 다른 주장에 대해서도 동일하게 적용될 수 있음을 서술할 것이다.

• 대한조선학회지
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• 제4권1호
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• pp.35-48
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• 1967

• 대한기계학회논문집
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• 제19권3호
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• pp.741-750
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• 1995

The turbulent buoyancy-driven flow in 2-dimensional enclosed cavities heated from the vertical side is numerically calculated for both cases of a Rayleigh number of 5*10$^{10}$ for air and 2.5*10$^{10}$ for water. Three different turbulence models are considered : standard k-.epsilon. model of Ozoe and low-Reynolds-number model of Lam and Bremhorst, and another low-Reynolds-number model of Davidson. The results indicate that the use of low-Reynolds number models is recommended for the indoor airflow computation, and the results from Davidson model are reasonably close to the reported experimental data. A sensitivity study shows that the amounts of wall-heat transfer and the velocity profiles with the Lam and Bremhorst model largely depend on the choice of the wall function for .epsilon..

• 대한화학회지
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• 제36권2호
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• pp.329-334
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• 1992

단백질 수용액 중의 초음파흡수 mechanism을 규명하기 위하여 pH 7의 소혈청 albumin(BSA)수용액의 초음파흡수 측정을 주파수 100 kHz에서 1600 MHz에 걸쳐 행하였다. 측정방법은 plano-concave 공명법(0.1${\sim}$10 MHz)과 고분해능 Bragg 반사법(120${\sim}$1600 MHz)을 사용하였다. pH7에서의 초음파흡수스펙트럼은 Davidson-Cole 분포식의 거울상인 분포함수를 사용한 완화곡선과 일치하였다. 이 완화현상을 BSA 분자의 수화평행에 의한 것으로 해석하였다.

• 한국유변학회:학술대회논문집
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• 한국유변학회 2001년도 Australian-Korean Rheology Conference 2001
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• pp.152.5-153
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• 2001

(No abstract, see full-text)