• Elastomers and Composites
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• 제55권1호
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• pp.59-66
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• 2020

Herein, we investigated the thermal conductivity and thermal stability of natural rubber composite systems containing hybrid fillers of boron nitride (BN) and aluminum nitride (AlN). In the hybrid system, the bimodal distribution of polygonal AlN and planar BN particles provided excellent filler-packing efficiency and desired energy path for phonon transfer, resulting in high thermal conductivity of 1.29 W/mK, which could not be achieved by single filler composites. Further, polyethylene glycol (PEG) was compounded with a commonly used naphthenic oil, which substantially increased thermal conductivity to 3.51 W/mK with an excellent thermal stability due to facilitated energy transfer across the filler-filler interface. The resulting PEG-incorporated hybrid composite showed a high thermal degradation temperature (T₂) of 290℃, a low coefficient of thermal expansion of 26.4 ppm/℃, and a low thermal distortion parameter of 7.53 m/K, which is well over the naphthenic oil compound. Finally, using the Fourier's law of conduction, we suggested a modeling methodology to evaluate the cooling performance in thermal management system.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.409-409
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• 2014

Recently hexagonal boron nitride (h-BN), III-V compound of boron and nitrogen with strong covalent $sp^2$ bond, is a 2 dimensional insulating material with a large direct band gap up to 6 eV. Its outstanding properties such as strong mechanical strength, high thermal conductivity, and chemical stability have been reported to be similar or superior to graphene. Because of these excellent properties, h-BN can potentially be used for variety of applications such as dielectric layer, deep UV optoelectronic device, and protective transparent substrate. Ultra flat and charge impurity-free surface of h-BN is also an ideal substrate to maintain electrical properties of 2 dimensional materials such as graphene. To synthesize a single or a few layered h-BN, chemical vapor deposition method (CVD) has been widely used by using an ammonia borane as a precursor. Ammonia borane decomposes into hydrogen (gas), monomeric aminoborane (solid), and borazine (gas) that is used for growing h-BN layer. However, very active monomeric aminoborane forms polymeric aminoborane nanoparticles that are white non-crystalline BN nanoparticles of 50~100 nm in diameter. The presence of these BN nanoparticles following the synthesis has been hampering the implementation of h-BN to various applications. Therefore, it is quite important to grow a clean and high quality h-BN layer free of BN particles without having to introduce complicated process steps. We have demonstrated a synthesis of a high quality h-BN monolayer free of BN nanoparticles in wafer-scale size of $7{\times}7cm^2$ by using CVD method incorporating a simple filter system. The measured results have shown that the filter can effectively remove BN nanoparticles by restricting them from reaching to Cu substrate. Layer thickness of about 0.48 nm measured by AFM, a Raman shift of $1,371{\sim}1,372cm^{-1}$ measured by micro Raman spectroscopy along with optical band gap of 6.06 eV estimated from UV-Vis Spectrophotometer confirm the formation of monolayer h-BN. Quantitative XPS analysis for the ratio of boron and nitrogen and CS-corrected HRTEM image of atomic resolution hexagonal lattices indicate a high quality stoichiometric h-BN. The method presented here provides a promising technique for the synthesis of high quality monolayer h-BN free of BN nanoparticles.

• 약학회지
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• 제42권3호
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• pp.257-264
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• 1998

5-Methylthebaine was obtained by treating thebaine with n-butyllithium and methylfluorosulfonate. Hetero Diels-Alder reaction of thebaine and 5-methylthebaine with trifluoroacet aldehyde afforded 14-${\beta}$-(triflu-oro-2-hydroxyethyl)codeine (2) and 14-${\beta}$-(trifluoro-2-hydroxyethyl)-5-methylcodeinone (9). 6-${\alpha}$-OH compound (4) was obtained by employing $CeCl_2$ and $NaBH_4$. After synthesized a derivative substituted for 3-OH (5), using boron tribromied, We synthesized a new derivative that make double bond in C-7, C-8 into epoxode (6), (10). Through inspecting an influence on structure-activity and analgetic action, we are going to examine which opiold acceptor has a selectivity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.900-902
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• 1999

This paper deals with the interrupting characteristics of fuses element in different media of arc extinguisher. Aluminum hydro-oxide, boron nitride, silica and there size have been investigated here for their prospects as filling media in heavy current, high breaking capacity fuses. The result of these study are compared with those on silica sand at high current. This study demonstrates that silica sand is far superior filler in fuses for heavy current interrupting then the compound tested.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.473-474
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• 2006

Boron Phosphide films were deposited on (111) Si substrate at $650^{\circ}C$, by the reaction of B2H6 with PH3 using APCVD. N2 was carried out as carrier gas. The optimal gas rates were $20\;m{\ell}/min$ for B2H6, $60\;m{\ell}/min$ for PH3 and $1\;{\ell}/min$ for N2. After as grown the films were insitu annealed for 1hour in N2 ambient at $550^{\circ}C$ and measured. The measurement of AFM shows that the RMS is $29.626{\AA}$ for the reaction temperature at $650^{\circ}C$. The measurement of XRD shows that the films have the orientation of (101). Also, the measurement of AES is shown that the films have B13P2 stoichiometry.

• Carbon letters
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• 제5권3호
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• pp.113-117
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• 2004

The mesophase pitch was prepared by adding 1~10 wt% of the borane-pyridine complex (BPC) to decant oil. It was prepared in a reactor held at $450^{\circ}C$ for 2 h in $N_2$ atmosphere. The mesophase pitches were analyzed using thermogravimetric analyzer (TGA), melting point apparatus, X-ray diffraction (XRD) and polarized optical microscope. The coke yield, softening point, toluene insoluble, density and content of anisotropy in the mesophase pitches were increased with BPC contents. The XRD profiles did not show any effect of addition of BPC on the formation of mesophase pitch, while the crystallinity of mesophase pitches was increased when the materials were heat treated with boron compound.

• Bulletin of the Korean Chemical Society
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• 제9권3호
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• pp.176-179
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• 1988

3-Methoxy-4-cyano-2,9-dioxabicyclo[4.3.0]non-3-e ne (1) was prepared by (4 + 2) cycloaddition reaction of methyl ${\alpha}$-cyanoacrylate with 2,3-dihydrofuran. Compound 1 was ring-open polymerized by cationic catalyst such as boron trifluoride etherate to obtain alternating head-to-head (H-H) copolymer (2) of methyl $\alpha$ -cyanoacrylate and 2,3-dihydrofuran. For comparison, head-to-tail (H-T) copolymer (3) was also prepared by free radical copolymerization of the corresponding monomers. The H-H copolymer exhibited minor differences in its $^1H$-NMR and IR spectra, but in the $^{13}C$-NMR spectra significant differences were observed between the H-H and H-T copolymers. All of the H-H and H-T copolymers were soluble in common solvents and the inherent viscosities were in the range 0.2-0.3 dl/g.

• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1642-1651
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• 2021

In this study, isophtalic neopentyl glycol polyester (NPG-PES) based composites with different loading ratios of pure tungsten metal (W), tungsten (VI) oxide (WO₃), tungsten boron (WB) and tungsten carbide (WC) composites were prepared as alternative shielding materials for ionizing electromagnetic radiation (IEMR) shielding. Structural characterizations of the composites were done. Gamma spectrometric analysis of composites for 80-2000 keV energy range was performed and their usability as IEMR shielding was discussed. As a result, the produced composites showed a shielding performance of 60-100% of the lead (the most widely used IEMR shielding material) depending on the reinforcement material, reinforcement loading rate and experimental conditions. Thus, it was reported that produced composites could be an alternative to lead shieldings that have several disadvantages as toxic properties, difficulty of processing and inelasticity.

• 한국화재소방학회논문지
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• 제34권1호
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• pp.1-10
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• 2020

본 연구는 건축 및 내구재용 목재인 편백 목재에 붕소/실리콘 졸 화합물을 처리한 후 화재위험성을 연기 유해성에 대하여 연기성능지수(SPI), 연기성장지수(SGI)와 연기강도(SI)를 중심으로 조사하였다. 화합물은 Tetraethoxyorthosilicate를 Boronic acid와 Boric acid 유도체와 반응시켜 합성하였다. 연기 특성은 편백목재에 대하여 Cone calorimeter (ISO 5660-1) 장비를 이용하여 조사하였다. 화재강도는 50 kW/㎡의 외부 열 유속(External heat flux)으로 고정시켰다. 연소 반응 후 측정된 연기성능지수는 편백목재와 비교하여 13.4~126.7% 증가하였다. 연기성능지수에 의한 화재위험성은 편백목재, PBA/Si, IBBA/Si, BA/Si 순서로 감소하였다. 연기성장지수는 편백목재와 비교하여 12.0~57.5% 감소하였다. 연기성장지수에 의한 화재위험성은 편백목재, PBA/Si, IBBA/Si, BA/Si 순서로 낮아졌다. 연기강도에 의한 화재위험성은 3.2~57.8% 감소하였으며 편백목재, PBA/Si, IBBA/Si, BA/Si 순서로 낮아졌다. CO_peak 농도는 85~93 ppm였으며 공시편과 비교하여 37~43% 감소하였다. 화재위험성을 연기유해성에 대해 종합적으로 평가하면 편백목재, PBA/Si, IBBA/Si, BA/Si순서로 낮아졌다.

• 한국산림과학회지
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• 제58권1호
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• pp.17-22
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• 1982

은기(銀寄)밤나무 4년생(年生)을 1979년(年)부터 1980년(年)까지 2년간(年間) 시비시험(施肥試驗)을 실시(實施)하던 중(中) 1980년도(年度)에 일기불순(日氣不順)으로 일조량(日照量)이 부족(不足)하게 되었던 바 각처리별(各處理別) 시비시험중(施肥試驗中) 특(特)히 고토첨가시용구(苦土添加施用區)가 밤나무의 생장(生長)도 양호(良好)하고 밤 수확량(收穫량量)도 증대(增大)되었다. 1) 밤나무 생장(生長)에 있어서 동일시비수준(同一施肥水準)에서도 비료삼요소(肥料三要素)와 붕소(硼素) 및 고토(苦土) 시용구(施用區)가 삼요소시비구(三要素施肥區)보다 약(約)20% 정도생장(程度生長)이 양호(良好)하였다. 2) 밤수확량(收穫量)에 있어서도 시비시험일차년도(施肥試驗一次年度)인 1979년(年) 11月(월) 14일(日) 이상난동(異常暖凍)으로 인(因)하여 다소(多小)의 냉해피해(冷害被害)는 있었으나 일조량(日照量)은 정상적(正常的)이여서 6월(月)서 9월(月)까지 1일(日) 평균일조량(平均日照量)은 7시간(時間)으로 밤수확량(收穫量)은 시료삼요소(試料三要素)의 시비지수(施肥指數) 100에 대(對)하여 비료삼요소(肥料三要素) 및 붕소시비구(硼素施肥區)가 167이고 비료삼요소(肥料三要素) 붕소(硼素) 및 고토시비구(苦土施肥區)는 207dldT다. 3) 시비시험삼차년도(施肥試驗三次年度)인 1980년도(年度)에는 일기불순(日氣不順)으로 일조량(日照量)이 1일(日) 평균(平均) 3.8시간(時間)으로서 이와 같은 일조량(日照量) 부족(不足) 현상하(現狀下)에서는 밤수확량(收穫量)은 비료삼요소시비구(肥料三要素施肥區)의 시비지수(施肥指數) 100에 대(對)하여 비료삼요소(肥料三要素) 및 붕소함유복비시비구(硼素含有複肥施肥區)는 620이고 비료삼요소(肥料三要素), 붕소(硼素) 및 고토함유복비구(苦土含有複肥區)에서는 741로서, 비료삼요소(肥料三要素) 및 붕소시비구(硼素施肥區)보다도 비료삼요소(肥料三要素), 붕소(硼素) 및 고토(苦土) 시비구(施肥區)가 약(約) 21%가 더 증수(增收)되었으며 비료삼요소시비구(肥料三要素施肥區)보다는 7배이상(倍以上)의 밤수확(收穫)이 있었다. 4) 이상(以上)의 결과(結果)로 보아 고토(苦土)(MgO)가 토양중(土壤中) 0.82me/100g 미만(未滿)일때에는 MgO의 시비효과(施肥效果)가 크게 나타날 뿐더러 일조량부족시(日照量不足時)는 MgO의 시비(施肥)로 녹색식물(綠色植物)의 탄소동화작용(炭素同化作用)을 활발(活潑)히 하게 하며 엽록소(葉綠素)를 조성(造成)하는 작용(作用)을 돕는 동시(同時)에 탄수화물형성(炭水化物形成)에도 큰 역할(役活)을 하게 되는 것으로 입증(立證)되었다.