Investigation of electromagnetic interference shielding effectiveness and electrical percolation of carbon nanotube polymer composites with various aspect ratios

Lee Dong-Kwan,Yoo Jongchan,Kim Hyunwoo,Park Sung-Hoon 한국탄소학회 2024 Carbon Letters Vol.34 No.1

Metals are recognized as electromagnetic interference (EMI) shielding materials owing to their high electrical conductivity. However, the need for light and flexible EMI shielding materials has emerged, owing to the heavyweight and inflexible nature of metals. Carbon nanotube (CNT)/polymer composites have been studied as promising flexible EMI shielding materials because of their lightweight nature due to the low density of CNTs and their high electrical conductivity. CNTs evenly dispersed in the polymer form an electrically conductive network, and the aspect ratio of the CNTs, which are one-dimensional nanofillers, is an important factor affecting electrical conductivity. In this study, we prepared three types of multi-walled carbon nanotubes (MWNTs) with different aspect ratios and fabricated polydimethylsiloxane (PDMS)/MWNT composites. Subsequently, the electrical conductivities and electrical percolation thresholds of the three PDMS/MWNT composites with different MWNT aspect ratios were measured to analyze the behavior of electrically conducting network formation according to the aspect ratio. Furthermore, the total EMI shielding effectiveness of each composite was determined to evaluate the effect of the MWNT aspect ratio on the EMI shielding. Reflection and absorption of electromagnetic wave were measured for the PDMS/MWNT composite with the largest aspect ratio to analyze the EMI shielding mechanism of the composite. Additionally, the effects of the MWNT content on the conductivity and EMI shielding performance were examined. The results provide valuable guidance for designing polymer MWNT composites with good electrical conductivity and EMI shielding performance under different aspect ratios of MWNTs.

시간부사 "증경(曾經)", "이경(已經)" 시상(時相) 자질 중한 대조분석

한경숙 ( Keung Shuk Han ) 경희대학교 비교문화연구소 2016 비교문화연구 Vol.42 No.-

본고는 현대중국어 시간부사 ‘曾經’과 ‘已經’의 관련 통사구조와 이에 상응하는 한국어 통사구조에 대한 고찰을 통하여 관련 구조 의미소 ‘時相(tense and aspect)’ 특징을 분석하였고 두 부사의 차이점을 찾아보았다. 아울러 중한 두 언어에서 이들이 나타내는 자질의 같은 점과 다른 점을 찾아냈고 이를 통하여 분석의 타당성(Descriptiveadequacy)을 확보하고 나아가 설명적 타당성(Explanatory adequacy)으로 이끌어 내고자 하였다. ‘曾經’은 상 범주의 하위 범주인 ‘과거경험상’, ‘성사상’, ‘과거지속상’ 등 자질을 갖고 있고 시제 범주의 하위 범주인 ‘과저시제’ ‘과거경험상’ 등 자질을 겸하고 있기도하다. 한국어의 ‘_었(았)_’, ‘_었었_’, ‘_적이 있_’과 대응관계를 이루고 있다. ‘曾經’은 하나의 통사구조에서 상과 시제 두 가지 자질을 갖고 있다. ‘已經’은 ‘완료상’과 완료상의 하위 범주인 ‘과거경험상’, 그리고 미완료상의 하위범주인 ‘과거지속상’ 등자질을 갖고 있고 시제 범주의 하위 범주인 ‘과거시제’, ‘현재시제’, ‘미래시제’ 등 시제 자질도 갖고 있으며 ‘상태의 변화’ 자질도 갖고 있다. 한국어의 ‘_었(았)_’, ‘_고_’,‘_었었_’, ‘곧’ 등과 대응관계를 이루고 있다. ‘曾經’과 동태조사 ‘過’를 비교하자면‘曾經’은 상 범주와 시제 범주를 겸하고 있다지만 ‘過’는 그 수식 범위가 술어밖에 없기에 상적 특징만 갖고 있다. 그리고 심층구조에서 ‘曾經’은 술어의 앞에서 술어를 포함한 술어 뒤에 출현한 조사, 목적어, 보어 모두와 통어 관계를 갖고 있지만, ‘過’는 그 앞의 술어만 수식한다. ‘已經’이 ‘진행상’ 자질을 가진 부사 ‘在’를 수식할 수 있지만, ‘曾經’은 불가능하다. 중국어와 한국어 두 언어는 이렇게 시간 표현에서 많은 차이를 보이고 있다. 중국어의 ‘과거경험상’, ‘성사상’, ‘과거지속상’ 등 상 자질과 ‘과거시제’ 자질을 갖고 있는 시간부사 ‘曾經’, 그리고 ‘과거경험상’, ‘과거지속상’ 등 상 자질 그리고 ‘과거시제’,‘현재시제’, ‘미래시제’ 등 시제 자질을 갖고 있는 시간부사 ‘已經’ 등이 한국어에서는 ‘완료상’, ‘지속상’ 자질과 ‘과거시제’ 자질로 대응된다는 것을 알 수 있다. 그만큼 중국어와 한국어 두 언어의 시간 체계는 서로 많은 차이를 보이고 있다. 이는 한중 두나라 사람들의 사유 방식의 차이와 문화적인 차이에서 비롯됐을 것으로 사료된다. Analysis of the syntactic structure of the modern Chinese adverbs for time ‘Cengjing (曾經)’ and ‘Yijing (已經)’ was performed to examine the tenses and aspects of the terms. The corresponding Korean words were examined and the terms in both languages were compared. The syntactic structures used in China and South Korea were found to be different. We hope the study of the Chinese language will help Korean students. ‘Cengjing (曾經)’ specific projects with ‘aspect’ of, ‘Past experience aspect’, ‘Past continuous aspect’, ‘Past continuous aspect’ in the past tense. [ED: unclear, please reword] These correspond to ‘_었 (았)_’, ‘_었었_’ in the Korean language. ‘Yijing (已經)’ has ‘finished phase’ of concrete projects, ‘Past experience aspect’, ‘Past continuous aspect’, also has a specific project tense, the ‘past tense’, ‘present tense’, ‘future tense’, and so tense. [ED: unclear, please reword] Adjectives can also be modified with a ‘change of status’. These correspond to ‘_었 (았)_’, ‘_고_’, ‘_었었_’, ‘곧’ etc. in Korean. ‘Cengjing (曾經)’ and the dynamic auxiliary ‘Guo (過)’ were compared to determine whether they have the aspect and tense features. However, ‘Guo (過)’ can only modify the predicate verb, so it possesses only aspect characteristics. ‘Cengjing (曾經)’ modifies the range more widely. ‘Yijing (已經)’ may be modified by the adverb ‘Zai (在)’ whereas ‘Cengjing (曾經)’ may not. Additionally, ‘Yijing (已經)’ can be modified by predicate adjectives and noun predicates, while ‘Cengjing (曾經)’ cannot.

Effects of interphase regions and tunneling distance on the electrical conductivity of polymer carbon nanotubes nanocomposites

Yasser Zare,Vesna Mišković‑Stanković,Kyong Yop Rhee 한국탄소학회 2019 Carbon Letters Vol.29 No.6

In this paper, an analytical model is developed for electrical conductivity of nanocomposites, particularly polymer/carbon nanotubes nanocomposites. This model considers the effects of aspect ratio, concentration, waviness, conductivity and percolation threshold of nanoparticles, interphase thickness, wettability between polymer and filler, tunneling distance between nanoparticles and network fraction on the conductivity. The developed model is confirmed by experimental results and parametric studies. The calculations show good agreement with the experimental data of different samples. The concentration and aspect ratio of nanoparticles directly control the conductivity. Moreover, a smaller distance between nanoparticles increases the conductivity based on the tunneling mechanism. A thick interphase also causes an increased conductivity, because the interphase regions participate in the networks and enhance the effectiveness of nanoparticles.

Effects of interphase regions and tunneling distance on the electrical conductivity of polymer carbon nanotubes nanocomposites

Zare Yasser,Mišković-Stanković Vesna,이경엽 한국탄소학회 2019 Carbon Letters Vol.29 No.6

In this paper, an analytical model is developed for electrical conductivity of nanocomposites, particularly polymer/carbon nanotubes nanocomposites. This model considers the effects of aspect ratio, concentration, waviness, conductivity and percolation threshold of nanoparticles, interphase thickness, wettability between polymer and filler, tunneling distance between nanoparticles and network fraction on the conductivity. The developed model is confirmed by experimental results and parametric studies. The calculations show good agreement with the experimental data of different samples. The concentration and aspect ratio of nanoparticles directly control the conductivity. Moreover, a smaller distance between nanoparticles increases the conductivity based on the tunneling mechanism. A thick interphase also causes an increased conductivity, because the interphase regions participate in the networks and enhance the effectiveness of nanoparticles.

탄소 나노튜브 나노유체의 열전도도에 대한 연구

김봉훈(Bong-Hun Kim) 대한설비공학회 2006 대한설비공학회 학술발표대회논문집 Vol.2006 No.6

An experimental study was conducted to investigate the effect of the morphology of CNT on the thermal conductivity of suspensions. The effective thermal conductivities of the samples were measured using asteady-state cut bar apparatus method. Enhancements based on the thermal conductivity of the base fluid are presented as functions of both the volume fraction and the temperature. Although functionalized SWNT produced a more stable and homogeneous suspension, the addition of small amounts of surfactant to suspensions of ""as produced"" SWNT demonstrated a greater increase in effective thermal conductivity than functionalized SWNT alone. The effective thermal conductivity enhancement corresponding to 1.0 percent by volume approached 10%, which was observed to be lower than expected, but more than twice the values, 3.5%, obtained for similar tests conducted using aluminum oxide suspensions. However, for suspensions of MWNT, the degree of enhancement was measured to be approximately 37%. It was postulated that the effect of clustering, resulting from the mutiple heat-flow passages constituted by interconnecting neighboring CNT clusters, played an important role in significant enhancement of effective thermal conductivity.

탄소 나노튜브 나노유체의 열전도도에 대한 연구

김봉훈(Bong-Hun Kim) 대한설비공학회 2007 설비공학 논문집 Vol.19 No.3

An experimental study was conducted to investigate the effect of the morphology of CNT (Carbon Nanotube) on the thermal conductivity of suspensions. The effective thermal conductivities of the samples were measured using a steady-state cut bar apparatus method. Enhancements based on the thermal conductivity of the base fluid are presented as functions of both the volume fraction and the temperature. Although functionalized SWNT (Single-Walled Carbon Nanotube) produced more stable and homogeneous suspensions, the addition of small amounts of surfactant to suspensions of ""as produced"" SWNT demonstrated a greater increase in effective thermal conductivity than functionalized SWNT alone. The effective thermal conductivity enhancement corresponding to 1.0% by volume approached 10%, which was observed to be lower than expected, but more than twice the values, 3.5%, obtained for similar tests conducted using aluminum oxide suspensions. However, for suspensions of MWNT (Multi-Walled Carbon Nanotube), the degree of enhancement was measured to be approximately 37%. It was postulated that the effect of clustering, resulting from the multiple heat-flow passages constituted by interconnecting neighboring CNT clusters, played an important role in significant enhancement of effective thermal conductivity.

현대중국어 조사 ‘中’, ‘着’ 상 자질 중한 대조 연구

한경숙(Han, Keung-Shuk) 동북아시아문화학회 2017 동북아 문화연구 Vol.1 No.51

Based on the analysis of the modern Chinese auxiliary ‘Zhong(中)’, ‘Zhe(着)’, The distinguishing features of the semantic features of ‘Zhong(中)’, ‘Zhe(着)’ are found out. The semantic features of ‘Zhong(中)’ correspond to ‘Zhe(着1)’ aspect features, But there are differences. Chinese auxiliary ‘Zhong(中)’ emphasizes the process of predicate verbs, And because it"s still a auxiliary in the process of Grammaticalization,So auxiliary ‘Zhong(中)’ can not bring the object behind. Moreover, Chinese auxiliary ‘Zhong(中)’ does not have the semantic features of ‘Zhe(着2), ‘Zhe(着3). ‘Zhong(中)’ equivalent to the Korean ‘_는 중_’, belonging to the continuing aspect. ‘Zhe(着1)’ is equivalent to the Korean ‘_고 있_’, Belong to dynamic continuous aspect. ‘Zhe(着2)’ is equivalent to the Korean ‘_어 있_’, belonging to the static aspect.In short, Chinese auxiliary ‘Zhong(中)’ is still in the development of aspect auxiliary, so, relatively speaking, the use is also subject to a lot of language environment and grammar constraints. In use, we must pay attention to the difference between the ‘Zhe(着)’. They have the following differences in the deep structure. [그림본문참조]

현대중국어 虚词 ‘的’ 상(aspect) 자질 중한 대조 분석

한경숙 대한중국학회 2015 중국학 Vol.51 No.-

In this paper, through the relevant syntactic structure and semantic comparison of Chinese and Korean Studies on Modern Chinese function words “De(的)”, “De(的)” was investigated whether has the character of aspect. Through the investigation discovery, Korean language in common and difference on time. In the concrete analysis, this paper also uses Chomsky Government and Binding Theory theory and Barriers theory, analyzes the tree diagram “De(的)” sentence, and through the investigation of the verb “De(的)” analysis, comparison of Chinese and Korean “De(的)” aspect feature. .

현대중국어 ?? '的' 상(aspect) 자질 중한 대조 분석

한경숙(Han Keung Shuk,韓京淑) 대한중국학회 2015 중국학 Vol.51 No.-

In this paper, through the relevant syntactic structure and semantic comparison of Chinese and Korean Studies on Modern Chinese function words "De(的)", "De(的)" was investigated whether has the character of aspect. Through the investigation discovery, Korean language in common and difference on time. In the concrete analysis, this paper also uses Chomsky Government and Binding Theory theory and Barriers theory, analyzes the tree diagram "De (的)" sentence, and through the investigation of the verb "De(的)" analysis, comparison of Chinese and Korean "De(的)" aspect feature. The results are as follows

시간부사 ‘在’의 형성 과정 및 도출 기제 연구 - 상 자질 비교분석을 중심으로 -

한경숙 단국대학교 동양학연구원 2016 東洋學 Vol.63 No.-

The syntax of Chinese adverb ‘Zai(在)’ and preposition ‘Zai(在)’, sememe, and the aspect of comparative analysis, examines the different point of time performance of Chinese adverbs ‘Zai (在)’ and prepositions ‘Zai(在)’. At the same time, through the investigation, the formation process of the adverb ‘Zai(在)’ is analyzed. The syntax of Chinese adverb ‘Zai(在)’ and reposition ‘Zai(在)’, is located in the time adverb and Preposition verb, their different syntactic functions. Preposition structure of adverbs of time ‘Zai(在)’ and behind it, the Predicate, dynamic auxiliary, complement, object, form commander, on the contrary, the Preposition ‘Zai(在)’ modify it behind the Predicate. In addition to these syntactic differences, there are some differences in aspect. When the Predicate is an action verb, the mental verb, the time adverb ‘Zai(在)’ and the Preposition ‘Zai(在)’ all have aspect. But when the Predicate is non repetitive verbs, if the subject is plural, adverb ‘Zai(在)’ will with AOP, Prepositional ‘Zai(在)’ but only said Predicate position, do not have the aspect. Preposition ‘Zai (在)’ with the adverb ‘Zai(在)’ environment at the same syntax, with the same aspect, can explain the adverb ‘Zai(在)’ from the Preposition ‘Zai(在)’ evolved. ‘Zai(在)+PREM+VP’ structure Presented Friendly ‘PREM’, After a change, ‘PREM’ fall off, forming a ‘Zai(在)+VP’ structure. That is, the Preposition ‘Zai(在)’ over a long period of grammar, they formed adverb usage. 본고는 현대중국어의 시간부사 ‘在’와 전치사 ‘在’의 통사구조, 의미소에 대한 분석 및 부사 ‘在’와 전치사 ‘在’ 의 상 자질에 대한 비교분석을 통하여 시간부사 ‘在’와 전치사 ‘在’ 사이의 시간 표현의 같음과 다름에 대해 규명하였다. 이런 공시적인 분석을 여러 시기 대표적인 중국어 문헌에 대한 통시적인 고찰과 더불어 중국어 시간부사 ‘在’의 형성 과정 및 도출 기제를 연구하였다. 부사 ‘在’가 그 뒤에 위치한 전치사구조, 술어, 술어에 따르는 조사, 보어, 목적어까지 통솔하여 이들과 ‘統 御’ 관계에 있는 반면 전치사 ‘在’구조는 그 뒤에 위치하고 있는 술어 동사만을 수식하고 있다. 이런 통사적 차이 외에도 시간부사 ‘在’와 전치사 ‘在’는 아래와 같은 상적 특징을 보이고 있다. 술어가 동작동사, 심리동사일때 부사 ‘在’와 전치사 ‘在’ 모두 상 자질을 구현하고 있고 술어가 순간동사이고 ‘反復性’을 가지고 있는 상황에서는 주어 어휘의 複數 여부와 상관없이 전치사 ‘在’와 부사 ‘在’ 모두 상 자질을 구현하고 있다. 그러나 술어가反復性이 없는 순간동사일 때 주어의 어휘 자질의 複數 여부에 따라 부사 ‘在’는 상 자질이 구현되지만, 전치사‘在’는 주어의 어휘 자질의 複數 여부와 상관없이 상 자질을 구현할 수 없고 오직 술어동사의 장소만을 나타내주고 있다. 심층구조에서 부사 ‘在’와 유사한 통사적 위치에 있고 서로 같은 상 자질을 갖고 있으며 동시에 술어 동사의장소를 나타내주고 있는 전치사 ‘在’는 일련의 문법화 과정을 거쳐 부사 ‘在’로 어휘화되었다. ‘在+PREM1)+VP’ 구조에서 ‘PREM’이라는 ‘處所詞(Premises)’에 ‘진행’ 의미가 강화되면서 일정한 문법화 과정을 거쳐 ‘處所詞’가대명사(Pronoun)인 ‘這裏’, ‘那裏’ 등으로 대체되었다가 ‘在+PRO2)+VP’ 구조에서 공간을 나타내는 전치사의목적어인 ‘PRO’가 탈락되면서 ‘在+VP’ 구조가 생겨나 전치사 ‘在’가 부사 ‘在’로의 어휘화과정을 마쳤다.