• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.377-384
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• 2010

We perform a comparative study to investigate the properties of the new energetic chain extender (AzPD). A series of poly(glycidyl azide)/poly(tetramethylene oxide)-based energetic segmented polyurethane (GAP/PTMG ESPU) with different chain extender, which is 3-azidopropane-1,2-diol (AzPD), 1,4-butane diol (1,4-BD), or 1,5 pentane diol (1,5-PD), was synthesized by solution polymerization in dimethyl formamide (DMF) and their phase behaviors were investigated. The ESPUs were characterized with Fourier transform infrared-attenuated total reflection spectroscopy (ATR FT-IR), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). The results of the ATR FT-IR analysis of the urethane carbonyl group region showed that the 'free' C=O fraction was higher in GAP/PTMG AzESPU (0.5) than GAP/PTMG BDESPU (0.44) and GAP/PTMG PDESPU (0.41) for 7 days samples after preparation and that it was similar in the range of 0.26~0.29 for three 60 days ESPU samples. DMA curves of the GAP/PTMG AzESPU for 7 days samples showed amorphous polymers, but GAP/PTMG BDESPU and GAP/PTMG PDESPU showed viscoelastic behaviors with rubbery plateau and the flow region. However, DMA curves of the GAP/PTMG AzESPU for 60 days samples showed viscoelastic behaviors with rubbery plateau and the flow region like GAP/PTMG PDESPU, but GAP/PTMG BDESPU did not show the flow region. From phase behaviors with ATR FT-IR, DSC and DMA analysis, GAP/PTMG AzESPU showed good phase-mixing between components. However, it represented viscoelastic behavior of TPE similar to GAP/PTMG PDESPM according to phase equilibrium progress with aging time.

• Journal of Korean Philosophical Society
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• no.116
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• pp.251-281
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• 2017

The Parmenidean tradition of logos which previous researches fail to fully appreciate has three dimensions of reality-knowledge-discourse. Parmenides is not just an ontologist, as the traditional view emphasizes, but also an epistemologist, as the revisionist view begins to emphasize, and, at the same time, a meta-discourser, as those two established views fail to embrace. In order to reach the third view which fully grasps such a dynamic and integrated feature of Parmenides, we should closely pay attention to the organic interconnectedness of three discourse parts of truth-doxa-proem, especially the significance of proem and meta-discourse. In the Eleatic tradition of discourse, the figure who clearly appreciated and further developed such an authentic feature of Parmenides' discourse is not, as one might easily expect, one of the second-generation Eleatics, but Gorgias who has commonly been positioned at the opposite side of Eleatism. This paper investigates how he actually both innovated and succeeded the Parmenidean tradition of logos; especially, it characterizes his discourse as an antilogy(antilogia) from within the tradition: as a 'devil' advocate' who complemented and completed Parmenidean persuasion by positing the Parmenidean tradition of logos as an arena of a huge intellectual discipline and cultivation, offering himself as a sparring partner to it, and bringing up an antilogy. In the process of this antilogy he performed in his rhetorical speeches such as the Encomium of Helen and the Defense of Palamedes he experimented and examined a possibility of persuasion operating independently from truth, which, however, is not merely sacrificing truth in favor of persuasiveness and probability (to eikos) as Plato criticized mainly focussing on his 'philosophical' writing On not-being. Rather, it was an 'opposition for opposition's sake' and serious play which purported to provide balance and flexibility to contemporary intellectual society which had too much inclined towards truth and knowledge and become stiff and to put weight on the opposite side of mainstream. It is wholly our eranos (i.e. our share of contribution) to summon and examine such sophistic tradition for the sake of the task of our times, not for the sake of Plato's task, that we should build up a healthy culture of discourse where we can share serious play.

• Strategy21
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• s.34
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• pp.236-261
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• 2014

The future role of nuclear extended deterrence in the security alliance between the United States and the Republic of Korea is currently a central concern. The gradually lessening role of reliance on nuclear weapons in US security policies broadly, combined with increasing North Korean nuclear capabilities and belligerence, raise fresh questions about the sufficiency of the "nuclear umbrella" as a pillar of the US-ROK defense posture. This article addresses the current and future role of nuclear extended deterrence in Korea in this dynamic context. The article reviews the longstanding trend toward reducing the overall size of the US nuclear arsenal, and assesses developments in US-ROK outlooks toward extended deterrence in response to the Obama administration's nuclear policies and North Korea's recent smaller-scale aggressions. The analysis finds that the challenges of deterrence credibility and allied reassurance are difficult and long-term. The analysis explains how these challenges emerge less from a shrinking US numerical arsenal size than from the sufficiency of specific nuclear and non-nuclear capabilities to meet emerging smaller-scale threats. The analysis also highlights the importance of broader strategic and political interaction in sustaining allied confidence in any joint security posture. The evaluation concludes that a strong US-ROK alliance relationship can be maintained while the size of the US nuclear arsenal continues to decline, in part because nuclear weapons in any deployment configuration are relatively ineffective means for deterring smaller-scale aggression. Nevertheless, continuing adjustment of the US-ROK extended deterrence posture to the evolving, complex and uncertain Korean peninsula security environment will remain an ongoing challenge. Finally, the article encourages further examination of the potential specific role ROK maritime forces might serve in enhancing deterrence of smaller-scale threats while minimizing risks of conflict escalation.