• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
• /
• pp.53-54
• /
• 2000

Measurements of the direct current resistivity, on multiwalled carbon nanotubes(MWNT) for field electron emitter source that had been screen printed in a thick film form were made as a function of temperature T in the range of 1.7K-390K. In this measuring temperature range, the electrical resistivity for the MWNT show that the main contribution to the conductivity comes form carries that hop directly between localized states executing variable range hopping processes. This thick-film form system for large area display showed a high bright light emission as well as very low turn-on field as like an individual MWNT system at room temperature. Furthermore, the electron emission characteristics followed well typical Fowler-Nordheim conduction under the vacuum.

• 한국전기전자재료학회논문지
• /
• 제17권2호
• /
• pp.242-247
• /
• 2004

Using Ar plasama and Fe-phthalocyanine, carbon nanofibers have been synthesized at a low temperature. Fe-phthalocyanine was used as a source material for this process. The carbon nanofibers were grown in random orientation with a diameter of about 100 nm and length up to 10${\mu}{\textrm}{m}$ on Si substrate. The synthesized carbon nanofibers exhibited excellent field emission characteristics. Protrusions with a nanometer size are observed at an angle of 60$^{\circ}$with respect to the nanofiber axis. Furthermore, we found the selective growth of nanofibers on a scratched substrates.

• Geomechanics and Engineering
• /
• 제8권2호
• /
• pp.133-152
• /
• 2015

Mathematical model has been developed for determination of temperature field in multilayer pavement and subgrade, which considers transfer of heat by conduction and convection, receiving of heat from total solar radiation and atmosphere emission, output of heat due to the emission from the surface of pavement. The developed model has been realized by the finite element method for two dimensional problem using two dimensional second order finite element. Calculations for temperature field have been made with the programme realized on the standard mathematical package MATLAB. Accuracy of the developed model has been evaluated by comparison of temperatures, obtained theoretically and experimentally. The results of comparison showed high accuracy of the model. Long-term calculation (within three months) has been made in pavement points in accordance with the data of meteorological station for air temperature. Some regularities have been determined for variation of temperature field.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
• /
• pp.154-154
• /
• 2000

FED(Field emission display)의 FEAs(Field emitter arrays)에 형성되어 있는 micro-tip 은 tip 표면의 오염이나 진공내부의 잔류가스에 대단히 민감하다. 특히, emitter 물질의 일함수 및 겉모양 같은 기하학적 요소에 민감한 전계방출 소자의 특성상 tip 선단이 oxidation 될 경우 일함수가 증가하여 전자방출에 필요한 구동전압이 증가하고 전자 방출의 불균일성이 커지는 문제점이 발생한다. 이에 고진공의 동작 환경 및 FEAs 제작과정이나 공기의 노출에 발생하는 tip 표면의 오염물질 제거가 요구된다. 따라서 본 연구에서는 40$\times$40mm2 FEAs에 laser power, scan speed을 달리하며 laser(cw Nd-YAG, 1064nm)을 조사하였다. laser cleaning 효과를 보기 위해 laser irradiation 전, 후에 진공도 5$\times$10-7torr irradiation 후에 emitter tip의 뚜렷한 기하학적 모양의 변화를 볼 수는 없었지만, I-V 특성이 향상 되는 것을 볼 수 있었다.

• Journal of Photoscience
• /
• 제9권3호
• /
• pp.51-55
• /
• 2002

The 77 K emission and excitation spectra, and 298 K infrared and absorption spectra of [Cr(progly)(2,2-tri)]CIO$_4$[progly=prolylglycinate,2,2-tri=N-(2-aminoethyl)-1,2-ethanediamine] have been measured. The vibrational intervals of the electronic ground state are extracted from emission and infrared spectra. The twelve electronic bands due to spin-allowed and spin-forbidden transitions were assigned. Using the observed electronic transitions, a ligand field analysis was performed to determine the metaligand bonding properties for the coordinated atoms. It is found that the carboxylate oxygen of the progly is a strong $\sigma$-and $\pi$-donor while the peptide nitrogen has weak $\pi$-donor property toward chromium(III) ion.

• Bulletin of the Korean Chemical Society
• /
• 제20권1호
• /
• pp.81-84
• /
• 1999

The emission and excitation spectra of [Cr(NH3)5(imH)](ClO4)3·H2O (imH=imidazole) taken at 77 K are reported. The 298 K visible and far-infrared spectra are also measured. The vibrational intervals of the electronic ground state are extracted from the far-infrared and emission spectra. The ten electronic bands due to spin-allowed and spin-forbidden transitions are assigned. Using the observed transitions, a ligand field analysis has been performed to determine the bonding properties of coordinated imidazole in the title chromium(Ⅲ) complex. It is confirmed that nitrogen atom of the imidazole ligand has a medium it-acceptor property toward chromium(Ⅲ) ion. The zero-phonon line in the excitation spectrum splits into two components by 181 cm-1, and the large 2Eg splitting can be reproduced by the ligand field theory.

• 한국농림기상학회지
• /
• 제17권4호
• /
• pp.326-332
• /
• 2015

우리나라 밭토양에서 국가고유의 온실가스 배출계수를 개발하기 위하여 2010년부터 2012년까지 봄 배추를 대상으로 재배기간 동안에 $N_2O$를 포집분석한 결과는 다음과 같다. 봄 배추 밭에서의 $N_2O$ 배출량은 정식 후 생육초기인 1개월 정도까지 높게 유지되다가 감소하는 경향을 보였다. 또한 생육초기에 수원지역의 $N_2O$ 배출량이 춘천지역보다 높았는데, 이는 수원의 강수량이 상대적으로 높은데 기인한다고 볼수 있다. 질소비료 시용량이 많을수록 $N_2O$ 배출량이 증가하는 경향을 보였으며, 회귀분석한 결과를 보면 99.8%의 상관성이 보였다. 본 연구에서 3년 동안의 봄 배추 재배기간 중 $N_2O$ 배출량을 분석하여 산정한 국가고유 $N_2O$ 배출계수는 0.0056kg Kg $N_2O-N/kg$ N이였다. 이러한 연구결과는 국가고유 $N_2O$ 배출계수를 등록과 더불어 국가 온실가스 배출량 산정에 적용하여 국가 및 지자체의 온실가스 배출량 감축에도 기여할 것이다.

• 한국환경농학회지
• /
• 제39권3호
• /
• pp.237-245
• /
• 2020

BACKGROUND: The closed chamber method is the most commonly used for measuring greenhouse gas emissions from upland fields. This method has the advantages of being simple, easily available and economical. However, uncertainty estimation is essential for accurate assessment of greenhouse gas emissions and verification of emission reductions. The nitrous oxide emissions from upland field is very important for the nitrogen budget in the agriculture sectors. Although assessment of uncertainty components affecting nitrous oxide emission from upland field is necessary to take account of dispersion characteristics, research on these uncertainty components is very rare to date. This study aims at elucidation of influencing factors on measurement uncertainty of nitrous oxide concentrations measured by an automated open closed chamber method from upland field. METHODS AND RESULTS: The nitrous oxide sampling system is located in the upland field in Gyeonggi-do Agricultural Research and Extension Services (37°13'22"N, 127°02'22"E). The primary measurement uncertainty components influencing nitrous oxide concentrations (influencing factors) investigated in this research are repeatability, reproducibility and calibration in the aspects of nitrous oxide sampling and analytical instrumentation. The magnitudes of the relative standard uncertainty of each influencing factor are quantified and compared. CONCLUSION: Results of this study show what influencing factors are more important in determination of nitrous oxide concentrations measured using the automated open closed chambers located in the monitoring site. Quantifying the measurement uncertainty of the nitrous oxide concentrations in this study would contribute to improving measurement quality of nitrous oxide fluxes.

• 전기전자학회논문지
• /
• 제28권1호
• /
• pp.38-45
• /
• 2024

간단한 자기장 감금이 레이저 유도 플라즈마의 전하 입자들에 미치는 영향이 논의 되었다. 자기장 영향에 대한 이전 연구들은 주로 플라즈마 방전 세기의 향상이나 수명시간 연장에 집중되었다. 이와 대조적으로, 본 개발은 과거에 거의 다뤄지지 않았던, 플라즈마 소멸에 대해 연구하였다. 이는 플라즈마를 활용한 기술개발에 혁신적인 도움이 될 것으로 기대한다. Nd:YAG 레이저(1064 nm, 6 ns)가 3가지 타입의 금속 물질(Al, Ti, STS)과 공기 중에 집광되었다. Nd₂Fe₁₄B 자석으로 0.4T 크기의 자기장을 만들었고, 이를 레이저 유도 플라즈마에 관통시켰다. 플라즈마 스펙트럼은 레이저 파워와 분광기의 딜레이 타임을 조정해 가면서 자기장 여부에 따른 수치가 측정되었다. O I(777.42 nm), Fe I (520.447 nm), Ti I (503.649 nm), Al I (396.147 nm) 스펙트럼 분석을 통해 자기장에 의한 플라즈마의 소멸이 특정 조건에 상관없이 항상 촉진됨을 독점적으로 발견하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.311-311
• /
• 2009

Carbon nanotubes (CNTs) belong to an ideal material for field emitters because of their superior electrical, mechanical, and chemical properties together with unique geometric features. Several applications of CNTs to field emitters have been demonstrated in electron emission devices such as field emission display (FED), backlight unit (BLU), X-ray source, etc. In this study, we fabricated a CNT cathode by using filtration processes. First, an aqueous CNT solution was prepared by ultrasonically dispersing purified single-walled CNTs (SWCNTs) in deionized water with sodium dodecyl sulfate (SDS). The aqueous CNT solution in a milliliter or even several tens of micro-litters was filtered by an alumina membrane through the vacuum filtration, and an ultra-thin CNT film was formed onto the alumina membrane. Thereafter, the alumina membrane was solvated by acetone, and the floating CNT film was easily transferred to indium-tin-oxide (ITO) glass substrate in an area defined as 1 cm with a film mask. The CNT film was subjected to an activation process with an adhesive roller, erecting the CNTs up to serve as electron emitters. In order to measure their luminance characteristics, an ITO-coated glass substrate having phosphor was employed as an anode plate. Our field emitter array (FEA) was fairly transparent unlike conventional FEAs, which enabled light to emit not only through the anode frontside but also through the cathode backside, where luminace on the cathode backside was higher than that on the anode frontside. Futhermore, we added a reflecting metal layer to cathode or anode side to enhance the luminance of light passing through the other side. In one case, the metal layer was formed onto the bottom face of the cathode substrate and reflected the light back so that light passed only through the anode substrate. In the other case, the reflecting layer coated on the anode substrate made all light go only through the cathode substrate. Among the two cases, the latter showed higher luminance than the former. This study will discuss the morphologies and field emission characteristics of CNT emitters according to the experimental parameters in fabricating the lamps emitting light on the both sides or only on the either side.