• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.399-408
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• 2010

The characteristics of lifted laminar propane flames diluted with nitrogen have been investigated experimentally to elucidate self-excitation and the effects of flame curvature. Flame oscillation modes are classified as follows: oscillation induced by heat loss, a combination of oscillations induced by heat loss and buoyancy, and a combination of the oscillations induced by heat loss and diffusive thermal instability. It is shown that the oscillation induced only by heat loss is not relevant to the diffusive thermal instability and hydrodynamic instability caused by buoyancy; this oscillation is observed under all lift-off flame conditions irrespective of the fuel Lewis number. These experimental evidences are displayed through the analysis of the power spectrum for the temporal variation of lift-off height. The possible mechanism of the oscillation induced by heat loss is also discussed.

• Korean Journal of Logic
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• v.16 no.1
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• pp.45-59
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• 2013

In his book Worlds and Individuals: Possible and Otherwise, Takashi Yagisawa Yagisawa argues that his own theory is better than Lewis's theory by showing that his own theory can deal with important objections to modal realism more successfully than Lewis's. In particular, Yagisawa claims that by adopting modal tenses, he can respond to many important objections to modal realism in a uniform way. In this paper, I argue that Lewis can also successfully respond to Peacocke's objection in an exactly parallel way to Yagisawa's by distinguishing existence at the actual world from existence at other possible worlds and that Yagisawa's response to van Inwagen's objection does not succeed. I conclude that Yagisawa fails to show that his own theory is better than Lewis's.

• Polymer(Korea)
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• v.38 no.5
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• pp.650-655
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• 2014

The degradation characteristics of perfluoropolyether (PFPE) derivatives currently being used as computer hard disk lubricants have been investigated. Especially, we considered the effects of end group on degradation behavior of PFPE derivatives. It was found that the degradation of PFPE derivatives in the presence of $Al_2O_3$ involves two degradation mechanisms such as thermal degradation and Lewis acid disproportionation by $AlF_3$ which was mainly formed by oxide-to-halide reaction between $Al_2O_3$ and the degraded PFPE. The end groups were strongly related to Lewis acid disproportionation of PFPE derivatives, and it is due to the difference of electron donating ability in the each end groups. Even if PFPE derivatives have same repeating unit in the main chain, Lewis acid disproportionation was prohibited by higher electron donating ability by the end group which caused the high electron density at the acetal group in the repeating unit.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.8.1-8.1
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• 2005

• Korean Journal of Logic
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• v.6 no.1
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• pp.33-50
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• 2003

본 논문에서 필자는 기존의 양상 허구주의의 번역 체계가 가지고 있는 세가지 난점을 극복할 수 있는 양상 허구주의의 새로운 번역 체계를 제시한다. 이 세 난점이란 (1) 많은 세계들의 존재를 받아들이지 않을 수 없게 된다. (2) 세계 간의 비교를 하게 하는 양상 진술문을 제대로 번역할 수 없다 (3) 어떤 양상 진술문에 내해 잘못된 진리치를 부여한다 이다. 이 세 난점을 극복하기 위한 필자의 제안은 세계-양화사의 범위 안에 등장하는 양화사들이 주어진 세계 내의 사물들만을 범위 내에 포함하는 루이스의 초기 번역 체계나 비한정적 양회사를 도입하는 루이스의 후기 번역 체계를 받아들이는 대신, 양화사를 조금씩 조금씩 비한정시키는 (unrestrict) 시키는 것이며, 필지 공식 번역 체계는 우주 (세계)의 부분전체론적 합으르 정의되는 "다우주(muitiverse)"라는 새로운 용어를 도입함으로써 얻어진다. 필자의 공식 번역 체계는 다음과 같다: P가 가능하다 iff PW에 의하면 P가 잠인 다우주가 존재한다 P가 필연적으로 참이다 iff PW에 의하면 모든 다우주에서 P가 참이다 마지막으로 필자는 비한정적인 세계 간의 비교를 하게 하는 양상 진술문을 적절하게 번역하기 위해서 필자의 번역 체계에 약간의 수정을 가한다.

• Korean Journal of Logic
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• v.5 no.2
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• pp.23-38
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• 2002

시간에 따른 개체의 변화를 설명하기 위해서는 한 개체가 다른 시간에 서로 다른 속성을 소유할지라도 동일한 하나의 개체로 취급되어야 한다. 그러나 이러한 사실은 개체의 개별화를 위한 라이프니츠의 법칙에 적용될 경우 모순을 야기한다. 개체의 변화와 관련된 이러한 문제를 해결하려 시도한 가장 대표적인 이론은 루이스의 이론이라 할 수 있다. 루이스는 개체의 변화와 관련된 문제를 해결하려한 시도는 e-존속이론과 p-존속이론으로 구분되는데 자신의 이론인 p-존속이론만이 개체의 변화와 관련된 문제를 성공적으로 해결할 수 있는 대안이라 주장하고 있다. 그러나 필자의 생각으로는 그의 이론도 시공 속에서의 개체들의 변화에 대한 실질적인 설명을 포기한 것으로 보이고 시간적 부분이란 설명되지 않은 형이상학적 개념을 도입하고 있다는 결정적 약점을 안고 있다.

• 정보보호뉴스
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• s.138
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• pp.46-49
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• 2009

흑인으로서는 최초로 대중적 사랑을 받았던 유명한 권투선수 조 루이스는 빈정거리듯 상대 선수에게 말했다. "도망칠 수는 있지만 숨을 곳은 없으리라!" 일단 링에 올라서면 상대의 공격을 피할 수는 있지만 상대를 따돌리고 온전히 숨을 곳은 없다는 것이다. 어쩌면 오늘날 우리 모두는 '정보화 시대'라는 링 위에 이미 올라선 것인지도 모른다. 우리 모두의 개인정보는 백척간두에 놓였다. 달아나고 피해 볼 수는 있겠지만 안전하게 숨을 곳은 없는 것이다.

• Korean Journal of Logic
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• v.8 no.2
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• pp.59-84
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• 2005

Adams' Thesis, or the so-called equation Pr$(A{\rightarrow}C)$ = Pr(C|A) seems to express a correct relationship between the probabilities of conditionals and conditional probabilities. But D. K. Lewis has proved the remarkable fact that probabilities of conditionals are not conditional probabilities. In this paper 1 present a version of Lewis' triviality results and give an explanation why probabilities of conditionals are not conditional probabilities. A conditional probability of C given A has a peculiar properly in that its probability is insulated from not-A facts: the only thing relevant is the proportion of ways in which A is true which are also ways for C to be true. This peculiarity of conditional probability seems to put the great obstacle in the way of attempting to find a proposition such that its probability of being true systematically coincides with conditional probability of something else.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.4 s.247
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• pp.343-349
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• 2006

Systematic experiments in $CH_4/Air$ counterflow diffusion flames diluted with He have been undertaken to study the oscillatory instability in which lateral flame size was less than burner nozzle diameter and thus lateral heat loss could be remarkable at low global strain rate. The oscillatory instability arises for Lewis numbers greater than unity and occurs near extinction condition. The oscillation is the direct outcome from the advancing and retreating edge flame. The dynamic behaviors of extinction in this configuration can be classified into three modes; growing, harmonic and decaying oscillation mode near extinction. As the global strain rate decreases, the amplitude of the oscillation becomes larger. This is caused by the increase of lateral heat loss which can be confirmed by the reduction of lateral flame size. Oscillatory edge flame instabilities at low global strain rate are shown to be closely associated with not only Lewis number but also heat loss (radiation and lateral heat loss).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.9 s.252
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• pp.905-912
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• 2006

Experiments in low strain rate methane-air counterflow diffusion flames diluted with $CO_2$ have been conducted to investigate the flame extinction behavior and edge flame oscillation in which flame length is less than the burner diameter and thus lateral conductive heat loss in addition to radiative loss could be remarkable at low global strain rates. The critical mole fraction at flame extinction is examined in terms of velocity ratio and global strain rate. It is seen that flame length is closely relevant to lateral heat loss, and this sheets flame extinction and edge flame oscillation considerably. Lateral heat loss causes flame oscillation even at fuel Lewis number less than unity. Edge flame oscillations are categorized into three: a growing-, a harmonic- and a decaying-oscillation mode. Onset conditions of the edge flame oscillation and the relevant modes are examined with global strain rate and $CO_2$ mole fraction in fuel stream. A flame stability map based on the flame oscillation modes is also provided at low strain rate flames.