• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.134-135
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• 2007

Growth of cubic SiC has been carried out on oxided Si substrate using atmospheric pressure chemical vapor deposition (APCVD). Hexamethyldisilane (HMDS) was used as the single precursor and nonflammable mixture of Ar and $H_2$ was used as carrier gas. Epitaxial growth had performed depositions under the various $H_2$ conditions which were adjusted from 0 to 100 seem. The effects of $H_2$ was characterized by surface roughness, thickness uniformity, films quality and elastic modulus. Thickness uniformity and films quality were performed by SEM. Surface roughness and elastic modulus were investigated by AFM and Nano-indentor, respectively. According to the $H_2$ flow rate, Poly 3C-SiC thin film quality was improved not only physical but also mechanical properties.

• Particle and aerosol research
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• v.7 no.1
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• pp.31-44
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• 2011

The hourly volatile organic compounds(VOCs) concentrations between 2005 and 2008 at Bulgwang photochemical assessment monitoring station were investigated to establish a method for quality assurance and quality control(QA/QC) procedure. Systematic error, erratic error, and random error, which was manifested by outlier and highly fluctuated data, were checked and removed. About 17.3% of the raw data were excluded according to the proposed QA/QC procedure. After QA/QC, relative standard deviation for representing 15 species concentrations decreased from 94.7-548.0% to 63.4-125.8%, implying the QA/QC procedure is proper. For further evaluation about the adequacy of QA/QC procedure, principal components analysis(PCA) was carried out. When the data after QA/QC procedure was used for PCA, the extracted principal components were different from the result from the raw data and could logically explain the major emission sources(gasoline vapor, vehicle exhaust, and solvent usage). The QA/QC procedure based on the concept of errors is inferred to proper to be applied on VOCs. However, an additional QA/QC step considering the relationship between species in the atmosphere needs to be further considered.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.7-11
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• 2006

In this paper, it is reported that film-bulk-acoustic resonator with high c-axis oriented AIN film on $Mo/SiO_2/Si(100)$ using metal-organic-chemical-vapor deposition was fabricated. The resonant frequency and anti-resonant frequency of the fabricated resonator were observed with 3.189[GHz] and 3.224[GHz], respectively. The quality factor and the effective electromechanical coupling coefficient(${k_{eff}}^2$) were measured with 24.7 and 2.65[%], respectively. The conditions of AIN deposition were substrate temperature of $950[^{\circ}C]$, pressure of 20Torr, and V-III ratio of 25000. A high c-axis oriented AIN film with $4{\times}10^{-5}[\Omega{cm}]$ resistivity of Mo bottom electrode and $4[^{\circ}]$ of AIN(0002) full-width at half-maximum(FWHM) on $Mo/SiO_2/Si(100)$ was grown successfully. The FWHM value of deposited AIN film is useful for the RF band pass filter specification for GHz-band wireless local area network.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.141-144
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• 1997

High quality 3C-SiC epilayer was grown on Si(111) at 125$0^{\circ}C$ using chemical vapor deposition(CVD) technique by pyrolyzing tetramethylsilane(TMS). 3C-SiC epilayer was doped by tetramethylgallium(TMGa) during the CVD growth. The crystallinity of 3C-SiC was significantly enhanced by doping the gallium impurity.

• Carbon letters
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• v.14 no.3
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• pp.145-151
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• 2013

Graphene is a fascinating material with excellent electrical, optical, mechanical, and chemical properties. Remarkable progress has been made in the development of methods for synthesizing large-area, high-quality graphene. Recently, the chemical vapor deposition method has opened up the possibility of using graphene for electronic devices and other applications. This review covers simple and inexpensive methods to grow graphene using polymers as solid carbon sources; which do not require an additional process to transfer graphene from the growth substrate to the receiver substrate.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.3
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• pp.381-388
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• 2003

An experimental study was carried out to measure the heat transfer coefficient in flow boiling to mixtures of HFC-l34a and HCFC-123 in a uniformly heated horizontal tube. Tests were run at a pressure of 0.6 MPa and in the ranges of heat flux 1-50 kw/$m^2$, vapor quality 0-100 % and mass velocity 150-600 kg/$m^2$s. Heat transfer coefficients of mixture were less than the interpolated values between pure fluids both in the low quality region where the nucleate boiling is dominant and in the high quality region where the convective evaporation is dominant. Measured data of heat transfer are compared to a few available correlations proposed for mixtures. The correlation of Jung et. al. satisfactorily predicted the present data, but the data in lower quality was overpredicted and underpredicted the high quality data. The correlation of Kandlikar considerably underpredicted most of the data. and showed the mean deviation of 35.1%.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.5
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• pp.37-46
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• 2010

This study was carried out to develop new application field and obtain the basic data of mixed paper with wood pulp and chitosan fiber for producing functional paper. Two types of wood pulp, such as SwBKP and HwBKP, were mixed with chitosan fiber. Physical and optical properties, water vapor absorption, air permeability, antibacterial activity and ash were measured. And the surface morphology of manufactured paper was observed using SEM. The results are as follows. It was revealed that density, breaking length, burst index, tear index, folding endurance and brightness were reduced but water vapor absorption and air permeability were on the rise in the structural view of SwBKP according to increasing the chitosan fiber ratio. Those HwBKP added chitosan fiber were great not only in the strength but also water vapor absorption and air permeability except for brightness. The water vapor absorption was lower and the air permeability was higher in the HwBKP added various chitosan fiber ratios than those with no chitosan fiber. It is estimated that these properties were related with various mixed rate of chitosan fiber. Particularly, air permeability was strongly dependent on the mixed rate of chitosan fiber. The chitosan fiber has superior antibacterial property, comparing with wood fiber. Adding chitosan fiber to the wood pulp was found to have an excellent antibacterial activity, more than 90%. The ashes were determined within 0.5%. Special bonds between chitosan fiber and wood pulp was observed by SEM and it means that the chitosan fiber were combined equally in the interior of wood pulp. In conclusion, mixing wood pulp with chitosan fiber can not only improves the quality of paper but also extend the usage of paper as a functional paper by using inherent property of chitosan. After all, production of functional paper added chitosan fiber is expected for new valuable industry of paper.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.785-789
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• 2021

Paprika productivity is different even in the same quality greenhouse and in the same region. These differences are known to due to differences in various environmental factors. This study was conducted to investigate the difference in the level of various environmental factors between high-productivity (HPF) and low-productivity (LPF) greenhouses. The largest difference between the two greenhouses in the daily or weekly average values of major environmental factors was the CO₂ concentration, but the LPF was higher than the HPF, so it was not determined as a factor for the difference in productivity. Correlation analysis among 14 environmental factors showed a high correlation among irradiation or related factors in moisture. The regression coefficients of the linear regression model between vapor pressure deficit and relative humidity were -0.0202kpa in HPF and -0.0262kpa in LPF. In particular, in February and March, the vapor pressure deficit in LPF was 1.5kpa or more, and the cumulative vapor pressure deficit compared to the cumulative irradiation at the early period of cultivation increased rapidly. The reason for the low productivity in LPF is thought to be that the plant was affected by moisture stress due to high vapor pressure deficit and transpiration under low irradiation conditions in the early period of cultivation and in winter.

• Korean Journal of Materials Research
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• v.18 no.12
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• pp.664-668
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• 2008

Vapor phase polymerization of a conductive polymer on a $SiO_2$ surface can offer an easy and convenient means to depositing pure and conductive polymer thin films. However, the vapor phase deposition is generally associated with very poor adhesion as well as difficulty when patterning the polymer thin film onto an oxide dielectric substrate. For a significant improvement of the patternability and adhesion of Poly(3-hexylthiophene) (P3HT) thin film to a $SiO_2$ surface, the substrate was pre-patterned with n-octadecyltrichlorosilane (OTS) molecules using a ${\mu}$-contact printing method. The negative patterns were then backfilled with each of three amino-functionalized silane self-assembled monolayers (SAMs) of (3-aminopropyl) trimethoxysilane (APS), N-(2-aminoethyl)-aminopropyltrimethoxysilane (EDA), and (3- trimethoxysilylpropyl)diethylenetriamine (DET). The quality and electrical properties of the patterned P3HT thin films were investigated with optical and atomic force microscopy and a four-point probe. The results exhibited excellent selective deposition and significantly improved adhesion of P3HT films to a $SiO_2$ surface. In addition, the conductivity of polymeric thin films was relatively high (${\sim}13.51\;S/cm$).

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.391-392
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• 2012

Graphene is a perfectly two-dimensional (2D) atomic crystal which consists of sp2 bonded carbon atoms like a honeycomb lattice. With its unique structure, graphene provides outstanding electrical, mechanical, and optical properties, thus enabling wide variety of applications including a strong potential to extend the technology beyond the conventional Si based electronic materials. Currently, the widespread application for electrostatically switchable devices is limited by its characteristic of zero-energy gap and complex process in its synthesis. Several groups have investigated nanoribbon, strained, or nanomeshed graphenes to induce a band gap. Among various techniques to synthesize graphene, chemical vapor deposition (CVD) is suited to make relatively large scale growth of graphene layers. Direct growth of graphene on hexagonal boron nitride (h-BN) using CVD has gained much attention as the atomically smooth surface, relatively small lattice mismatch (~1.7％) of h-BN provides good quality graphene with high mobility. In addition, induced band gap of graphene on h-BN has been demonstrated to a meaningful value about ~0.5 eV.[1] In this paper, we report the synthesis of grpahene / h-BN bilayer in a chemical vapor deposition (CVD) process by controlling the gas flux ratio and deposition rate with temperature. The h-BN (99.99％) substrate, pure Ar as carrier gas, and $CH_4$ are used to grow graphene. The number of graphene layer grown on the h-BN tends to be proportional to growth time and $CH_4$ gas flow rate. Epitaxially grown graphene on h-BN are characterized by scanning electron microscopy, atomic force microscopy, and Raman spectroscopy.