• 한국분말재료학회지
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• 제25권2호
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• pp.120-125
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• 2018

Boron nitride nanotubes (BNNTs) are receiving great attention because of their unusual material properties, such as high thermal conductivity, mechanical strength, and electrical resistance. However, high-throughput and high-efficiency synthesis of BNNTs has been hindered due to the high boiling point of boron (${\sim}4000^{\circ}C$) and weak interaction between boron and nitrogen. Although, hydrogen-catalyzed plasma synthesis has shown potential for scalable synthesis of BNNTs, the direct use of $H_2$ gas as a precursor material is not strongly recommended, as it is extremely flammable. In the present study, BNNTs have been synthesized using radio-frequency inductively coupled thermal plasma (RF-ITP) catalyzed by solid-state ammonium chloride ($NH_4Cl$), a safe catalyst materials for BNNT synthesis. Similar to BNNTs synthesized from h-BN (hexagonal boron nitride) + $H_2$, successful fabrication of BNNTs synthesized from $h-BN+NH_4Cl$ is confirmed by their sheet-like properties, FE-SEM images, and XRD analysis. In addition, improved dispersion properties in aqueous solution are found in BNNTs synthesized from $h-BN+NH_4Cl$.

• 분석과학
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• 제5권2호
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• pp.199-202
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• 1992

$BF_2$를 50keV, 90keV로 에너지를 달리하여 주입한 실리콘 기판에 타이타늄을 sputter하여 Ti-slicide를 형성한 시편과 composite target을 사용하여 Ti-silicide를 형성한 시편을 준비하였다. Ti-silicide 형성시 boron의 거동을 SIMS(secondary ion mass spectrometry)로 분석하였다. Metal-Ti target을 사용한 경우 Ti-silicide 형성시 불순물들이 재분포하였으며 이온 주입 에너지가 작은 경우 심한 out-diffusion이 발생하였다. 한편 Composite target을 사용한 경우 거의 재분포가 발생하지 않고 안정된 boron의 분포를 보였다.

• 원예과학기술지
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• 제30권2호
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• pp.144-151
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• 2012

미량원소인 붕소(B)의 시비농도를 인위적으로 조절한 관비용액으로 '금향', '매향' 및 '설향' 딸기를 재배하면서 시비수준이 생육에 미치는 영향, 생육을 우수하게 유지할 수 있는 식물체의 한계농도, 그리고 B 과잉시비로 유발되는 생리장해의 특징을 구명하기 위하여 본 연구를 수행하였다. 0.25mM B 시비구에서 세 종류 딸기 품종의 생체중 및 건물 중이 가장 무거웠고 관부직경도 가장 굵었지만 B 시비농도가 높아짐에 지상부 생장량이 급격하게 감소하였다. B가 과다하게 시비되면 신생엽에서는 황화현상, 중간에 위치한 잎들에서는 잎 가장자리의 갈변 및 괴사현상, 그리고 하위엽들이 괴사하면서 안쪽으로 말리는 증상이 나타났다. 하위엽에서 나타나는 증상은 '금향'의 경우 2mM 이상의 처리구, '매향'과 '설향'은 0.5mM 이상의 시비구에서 잎 선단부의 갈변 및 괴사, 그리고 잎 내부에 갈변 및 괴사현상이 나타났다. B 시비농도가 증가하여도 다량원소중 양이온인 K, Ca 및 Mg 함량에는 차이가 나타나지 않았으며, 음이온인 인산 함량이 감소하는 경향을 나타냈다. B 시비농도가 증가할 때 '금향'과 '설향' 딸기에서 Fe 함량이 감소하였으며, Zn 함량이 증가하는 경향을 보였다. 건물중에 기초한 지상부 생장량의 90%와 이 때의 B 함량을 정상생육을 위한 최대한계점으로 간주할 때 '금향', '매향' 및 '설향' 딸기에서 식물체내 B 함량이 각각 25.1, 44.2 및 $62.5mg{\cdot}kg^{-1}$ 이하를 유지하도록 B 시비농도를 조절하여야 과잉피해를 방지할 수 있다고 판단하였다.

• Smart Structures and Systems
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• 제18권5호
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• pp.1029-1062
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• 2016

In this research, the nonlinear free vibration analysis of boron-nitride micro ribbon (BNMR) on the Pasternak elastic foundation under electrical, mechanical and thermal loadings using modified strain gradient theory (MSGT) is studied. Employing the von $K{\acute{a}}rm{\acute{a}}n$ nonlinear geometry theory, the nonlinear equations of motion for the graphene micro ribbon (GMR) using Euler-Bernoulli beam model with considering attached mass and size effects based on Hamilton's principle is obtained. These equations are converted into the nonlinear ordinary differential equations by elimination of the time variable using Kantorovich time-averaging method. To determine nonlinear frequency of GMR under various boundary conditions, and considering mass effect, differential quadrature element method (DQEM) is used. Based on modified strain MSGT, the results of the current model are compared with the obtained results by classical and modified couple stress theories (CT and MCST). Furthermore, the effect of various parameters such as material length scale parameter, attached mass, temperature change, piezoelectric coefficient, two parameters of elastic foundations on the natural frequencies of BNMR is investigated. The results show that for all boundary conditions, by increasing the mass intensity in a fixed position, the linear and nonlinear natural frequency of the GMR reduces. In addition, with increasing of material length scale parameter, the frequency ratio decreases. This results can be used to design and control nano/micro devices and nano electronics to avoid resonance phenomenon.

• Advances in materials Research
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• 제3권1호
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• pp.259-269
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• 2014

The boron-nitrogen-containing phenol-formaldehyde resin (BNPFR)/$SiO_2$ nanocomposites (BNPFR/$SiO_2$) were synthesized in-situ, and structure of BNPFR/$SiO_2$ nanocomposites was characterized by FTIR, XRD and TEM. The loss modulus peak temperature $T_p$ of BNPFR/$SiO_2$ nanocomposites cured with different nano-$SiO_2$ content are determined by torsional braid analysis (TBA). The thermal degradation kinetics was investigated by thermogravimetric analysis (TGA). The results show that nano-$SiO_2$ particulate with about 50 nm diameter has a more uniformly distribution in the samples. The loss modulus peak temperature $T_p$ of BNPFR/$SiO_2$ nanocomposite is $214^{\circ}C$ when nano-$SiO_2$ content is 6 wt%. The start thermal degradation temperature $T_{di}$ is higher about $30^{\circ}C$ than pure BNPFR. The residual rate (%) of nanocomposites at $800^{\circ}C$ is above 40 % when nano-$SiO_2$ content is 9 %. The thermal degradation process is multistage decomposition and following first order.

• 한국토양비료학회지
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• 제11권1호
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• pp.9-16
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• 1978

사과나무용 복합비료(複合肥料)의 합리적(合理的) 조성비(組成比)를 찾고자 사소첨가(硼素添加) 복비(複肥) 시제품(試製品)($N-P_2O_5-K_2O-B_2O_5-MgO$: 10-10-0.2-1.0)을 요소(尿素), 중과석(重過石), 염화가리(鹽和加里) 일반복비(一般複肥)(22-22-11)와 붕사(硼砂)를 사용(使用) 왜성(矮性)후지 일년생묘목(一年生苗木)과 수퍼타입스서크림슨 삼년생(三年生)을 비교적(比較的) 척박(瘠薄)한 삼개토양(三個土壤)에 주당총엽중(株當總葉重), 또는 주당신초장등(株當新稍長等) 생육량조사(生育量調査)로 실시(實施)하여 다음과 같은 결과(結果)를 얻었다. 1. 후지에서는 붕소첨가(硼素添加) 복비(複肥)>일반복비(一船複肥)>삼요소단비(三要素單肥)>삼요소단비(三要素單肥)+붕소(硼素)>붕소첨가복비(硼素添加複肥)+붕소증시(硼素增施)(17배(培))>무인산(無燐酸)의 순(順)으로 효과가 적어졌다. 2. 스타크림슨 삼년생(三年生)은 붕소복비(硼素複肥)+붕소(硼素) 및 인산증시(燐酸增施)>붕소복비(硼素複肥)>일반복비(一般複肥)>단비(單肥)>붕소복비(硼素複肥)+(붕소증시)硼素增施>단비(單肥)+붕소(硼素)>무인산(無燐酸)의 순(順)이었으며 척박(瘠薄)한 토양(土壤)에 퇴비(堆肥)를 사용(使用)치 않으면 붕소증시(硼素增施)에서 극히 불량(不良)하고 단비붕소(單肥硼素)가 가장 좋고 붕소첨가(硼素添加) 복비(複肥)가 다음이었다. 3. 붕소(硼素)만 증시(增施)되면 생육(生育)이 불량(不良)하였으나 인산(燐酸)과 동시(同時)에 증시(增施)되는 경우 효과가 나타나고 토양중(土壤中)에 붕소(硼素)가 삼요소(三要素)와 동일(同一)한 위치(位置)에 분포(分布)할 때 효과가 좋은 것으로 추정(推定)되었다. 4. 사과나무에 대(對)한 시비반응(施肥反應)은 엽폭(葉幅)에는 없으며 엽장(葉長)에서 인정(認定)되고 엽당중량(葉當重量)에서 잘 반영되는 것으로 보아 시비효과지표로 표고신장량(標高伸長量), 간주장(幹周長) 간비대량(幹肥大量)보다도 주당신초장(株當新稍長) 및 주당총엽중(株當總葉重)이 좋을것으로 보였다. 5. 사과용 붕소첨가(硼素添加) 복비(複肥)의 조성(組成)은 10-10-10-0.2보다 10-20-10-0.6($N-P_2O_5-K_2O-B_2O_5$)이 척박지(瘠薄地) 및 중간비옥도지용(中間肥沃度地用)으로 좋을 것으로 보였다. 6. 엽분석결과(葉分析結果) 붕소첨복비중(硼素添加複肥中) Mg가 Fe와 함께 엽중증가(葉重增加)에 기여(寄與)한 것으로 보여 Mg 효과가 인정(認定)되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.179-179
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• 2016

A radio-frequency (RF) Inductively Coupled Plasma (ICP) torch system was used for boron-nitride nano-tube (BNNT) synthesis. Because of electrodeless plasma generation, no electrode pollution and effective heating transfer during nano-material synthesis can be realized. For stable plasma generation, argon and nitrogen gases were injected with 60 kW grid power in the difference pressure from 200 Torr to 630 Torr. Varying hydrogen gas flow rate from 0 to 20 slpm, the electrical and optical plasma properties were investigated. Through the spectroscopic analysis of atomic argon line, hydrogen line and nitrogen molecular band, we investigated the plasma electron excitation temperature, gas temperature and electron density. Based on the plasma characterization, we performed the synthesis of BNNT by inserting 0.5~1 um hexagonal-boron nitride (h-BN) powder into the plasma. We analysis the structure characterization of BNNT by SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy), also grasp the ingredient of BNNT by EELS (Electron Energy Loss Spectroscopy) and Raman spectroscopy. We treated bundles of BNNT with the atmospheric pressure plasma, so that we grow the surface morphology in the water attachment of BNNT. We reduce the advancing contact angle to purity bundles of BNNT.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.2072-2077
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• 2020

The purpose of this study was to demonstrate the feasibility of sensing changes in a tumor during boron neutron capture therapy (BNCT) using a Monte Carlo simulation tool. In the simulation, an epi-thermal neutron source and a water phantom including boron uptake regions (BURs) were simulated. Moreover, this simulation also included a detector for positron emission tomography (PET) scanning and an adaptively-designed collimator (ADC) for PET. After the PET scanning of the water phantom, including the 511 keV source in the BUR, the ADC was positioned in the PET's gantry. Single prompt gamma rays were collected through the ADC during neutron irradiation. Then, single prompt gamma ray-based tomography images of different sized tumors were acquired by a four-step process. Both the signal-to-noise ratio (SNR) and tumor size were analyzed from each step image. From this analysis, we identified a decreasing trend of both the SNR and signal intensity as the tumor size decreased, which was confirmed in all images. In conclusion, we confirmed the feasibility of sensing changes in a tumor during BNCT using PET and an ADC through Monte Carlo simulation.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2004년도 International Conference Global Environmental Problems and their Health Consequences
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• pp.217-222
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• 2004

This study was conducted to estimate if the level of several chemical ingredients including alkanolamines or ethanolamines (EA) examined in the specific synthetic metalworking fluid (MWF) ‘A’ can cause anti-microbial activity and health effect. Three water-based MWF products (‘A’, ‘B’, and ‘C’) were studied every week for two months. Chemical ingredients such as formaldehyde, boron, EA, and copper were examined. In the sump where MWF ‘A’ was used, not only the total level of EA, monoethanolamine(MEA), diethanolamine(DEA) and triethanolamine(TEA), but also boron level were significantly higher than those of the other MWFs. ANOVA statistical tests indicated that levels of pH, alkalinity, boron, MEA, DEA and TEA in MWF ‘A’ were significantly higher than those in other MWF types. Correlation tests also found that levels of pH, alkalinity, boron, MEA, DEA and TEA in MWF ‘A’ are significantly correlated. We suggested the assumptions that excessive concentrations of EA, and borate at a high pH level, may cause anti-microbial resistance synergically. To demonstrate this assumption, additional study is needed to examine the relationship between the levels of microbes and excessive concentrations of EA, and borate at a high pH level.

• KSTLE International Journal
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• 제4권2호
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• pp.52-55
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• 2003

This study was conducted to estimate if the level of several chemical ingredients including alkanolamines or ethanolamines (EA) examined in the specific synthetic metalworking fluid (MWF) "A" can cause anti-microbial activity and health effect. Three water-based MWF products ("A", "B", and "C") were studied every week for two months (from June 1, 2002 to July 30, 2002). Chemical ingredients such as formaldehyde, boron, EA, and copper were examined. In the sump where MWF "A" was used, not only the total level of EA, monoethanolamine(MEA), diethanolamine(DEA) and triethanolamine(TEA), but also boron level were significantly higher than those of the other MWFs. ANOVA statistical tests indicated that levels of pH, alkalinity, boron, MEA, DEA and TEA in MWF "A" were significantly higher than those in other MWF types. Correlation tests also found that levels of pH, alkalinity, boron, MEA, DEA and TEA in MWF "A" are significantly correlated. We suggested the assumptions that excessive concentrations of EA, and borate at a high pH level, may cause anti-microbial resistance synergically. To demonstrate this assumption, additional study is needed to examine the relationship between the levels of microbes and excessive concentrations of EA, and borate at a high pH level.