• 말소리와 음성과학
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• 제9권3호
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• pp.7-15
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• 2017

The purpose of this study was to investigate the different aspects of word-initial liquid sounds in Korean according to generations. Five women in their 50s and seven in their 20s participated in the experiment. We examined FL (formant of liquids) and voice sustained time by using Praat software. Three English native speakers were asked to judge the Korean speakers' recorded speech samples for marking [l] or [r] using evaluation sheet. The results of the two experiments revealed three important aspects. First, there was a statistically significant difference between the two groups in the FL of the words 'racket' and 'ruby.' Second, we found statistically significant differences in 'rhythm', 'ruby' and 'litter' from the measurement of the duration of the acoustic data. Third, there was no difference in pronunciation between the two groups according to the phonemes of the original language. The results of this study showed that it is difficult to say that the duration of word-initial liquids and the phoneme difference of the original language are indicators to distinguish the word-initial liquids between generations. Also, it was seen that the pronunciation of Korean word-initial liquid sounds varied across generations.

• 공업화학
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• 제21권2호
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• pp.129-136
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• 2010

이온성 액체는 휘발성이 거의 없고, 열적 안정성이 높으며, 탄화수소화물에 잘 섞이지 않고, 다양한 무기 및 유기금속 화합물을 쉽게 용해시킬 뿐만 아니라 전기전도도가 높고 산도와 염기도를 용이하게 조절할 수 있는 등 독특한 물리화학적 성질로 인하여 청정용매, 촉매, 분리, 전해질, 바이오 분야에서 다양하게 응용되고 있다. 본 총설에서는 이온성 액체에 대한 기본지식과 함께 현재 이온성 액체를 응용한 상용화 예를 포함하여 이온성 액체의 다양한 활용분야, 특히 $CO_{2}$ 흡수 및 전환분야에 대한 최근 연구 동향을 기술하였다.

• 한국군사과학기술학회지
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• 제16권5호
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• pp.690-702
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• 2013

Ionic liquids(ILs) have been the most investigated chemicals among green solvents including water, glycerol, supercritical carbon dioxdie($scCO_2$). ILs are attracting organic as well as inorganic chemicals because most ionic liquids' vapor pressures are very low so that ILs are liquids phase at ambient conditions. ILs are composed of various anions and cations, thus chemists can design functionalized solvents and/or catalysts that can be used in specific synthetic reactions by means of combinations of different ions. Many scientists believe ILs being green materials because of its low vapor pressure as well as the flexibility in controlling the chemical and physical properties. In this review the author describes recent development of ILs focused on imidazolium and pyridinium ILs which are being most investigated presently. In order to apply this materials in industrial level, the toxicity matter must be resolved first. In this regard, the author describes recent research trend regarding environmental effects by ILs as well as some meaningful results as well.

• 공업화학
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• 제23권5호
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• pp.510-513
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• 2012

전통적인 화학적 환원법에 이온성액체를 사용하여 팔라듐 입자를 제조하였다. 이온성액체를 구성하는 양이온의 종류에 따라 형성된 팔라듐 입자는 다양한 크기와 모양을 가지는 것이 관찰되었다. 이는 이온성액체의 양이온이 길이에 따라 합성 중에 이온성액체들 간에 형성되는 구조체의 안정성에 차이를 보이기 때문이다. [$BF_{4}$] 음이온을 가지는 이온성액체 중 양이온의 알킬기가 hexyl인 이온성액체를 이용하여 합성된 팔라듐 입자가 가장 작고 균일하게 형성되었다.

• 공업화학
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• 제27권5호
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• pp.551-554
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• 2016

화학적 환원법에 이온성액체를 분산제로 사용하여 은 입자를 제조하였다. 이온성액체를 구성하는 양이온의 종류에 따라 제조된 은 입자는 다양한 구조를 가지는 것으로 관찰되었다. 이온성액체의 음이온에 상관없이 양이온의 알킬기의 길이가 길어질수록 은 입자가 작고 균일하게 형성되었다. 이는 이온성액체의 양이온이 길이에 따라 합성 중에 이온성액체들 간에 형성되는 구조체의 안정성에 차이를 보이기 때문이다. 조사된 7가지 이온성액체 중 [Omim][$PF_6$]가 은 입자 합성에 가장 효과적이었다.

• 말소리와 음성과학
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• 제3권1호
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• pp.51-65
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• 2011

This study attempts to investigate the interlanguage speech intelligibility benefit for listeners (ISIB-L), examining Chinese talkers' production of English liquids and its perception of native listeners and non-native Chinese and Korean listeners. An Accent Judgment Task was conducted to measure non-native talkers' and listeners' phonological proficiency, and two levels of proficiency groups (high and low) participated in the experiment. The English liquids /l/ and /r/ produced by Chinese talkers were considered in terms of positions (syllable initial and final), contexts (segment, word and sentence) and lexical density (minimal vs. nonminimal pair) to see if these factors play a role in ISIIB-L. Results showed that both matched and mismatched interlanguage speech intelligibility benefit for listeners occurred except for the initial /l/. Non-native Chinese and Korean listeners, though only with high proficiency, were more accurate at identifying initial /r/, final /l/ and final /r/, but initial /l/ was significantly more intelligible to native listeners than non-native listeners. There was evidence of contextual and lexical density effects on ISIB-L. No ISIB-L was demonstrated in sentence context, but both matched and mismatched ISIB-L was observed in word context; this finding held true for only high proficiency listeners. Listeners recognized the targets better in the non-minimal pair (sparse density) environment than the minimal pair (higher density) environment. These findings suggest that ISIB-L for English liquids is influenced by talkers' and listeners' proficiency, syllable position in association with L1 and L2 phonological structure, context, and word neighborhood density.

• 한국음향학회지
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• 제29권4호
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• pp.251-257
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• 2010

본 논문에서는 액체 매질 내 기포운에 의한 초음파의 감쇠 및 분산 특성을 다룬다. 액체 내 기포운은 다양한 기작에 의해 발생되며 이에 따라 기포운을 구성하는 기포들의 크기와 분포가 다양한 양상을 가지게 된다. 따라서 기포들의 크기와 분포에 따라 기포운의 감쇠와 분산 특성이 어떻게 변화하는지에 중점을 둔다. 특히 아직 보고된 바 없는 나노 기포운의 감쇠 및 분산 특성에 대하여 조명하고자 한다. 수치해석 결과, 기포운의 음향 감쇠 및 분산 특성은 구성 기포들의 첨예도에 따라 크게 변화하는 것으로 나타났다. 본 연구는 기포운 내 음향 전파의 심도 있는 이해에 일조할 것으로 기대한다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.123-124
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• 2006

Ionic liquids (ILs) are collecting keen interests as an advanced substituent of electrolyte solution as well as novel solvents. In the present talk, I will introduce some strategies to fix IL structure on polymer chains to prepare polar polymers with low glass transition temperature. Namely, cationic, anionic, and zwitterionic monomers have been prepared, and they have been homopolymerized or copolymerized to prepare polymer electrolytes with different properties. The polymers themselves showed very poor ionic conductivity, but it was improved by suitable spacer between charged site and main chain. Other unique characteristics of functional ILs and new polymerized ionic liquids will also be mentioned.

• The Korean Journal of Ceramics
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• 제3권4호
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• pp.269-273
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• 1997

Chemical composition of cement powder influences the setting time and early compressive strength development. The setting time increases as the amounts of zinc oxide and magnesium oxide are increased. For one day compressive strength development, a cement powder with a composition 90% ZnO, 8% MgO and 2% silica resulted in the highest strength (greater than 1, 090 kg/$\textrm{cm}^2$). Cement-forming liquids also need to be buffered, with both aluminum and zinc ions, for a good consistency and a higher strength of the zinc phosphate cement. These liquids control the setting reactions.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.310-313
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• 2003

Complex permittivities of human head simulating liquids were measured by a sample holder of terminated slotted coaxial line with a movable probe at mobile communication frequencies. The validity of the liquid measurement system was checked by experiments with the reference liquids. Liquids of ingredients for human brain suggested in IEEE draft and those made by the authors were measured by this slotted line system.