• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.38.2-38.2
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• 2011

폴리머 박막은 그 고유한 특성으로 인해 여러 산업적으로 널리 사용되고 있는 재료이다 예로 의약품이나 식품 포장지의 배리어, 전자부품의 절연체, 반도체 공정에서의 사용, 혹은 부식방지를 위해 사용 되어지기도 한다. 이 폴리머 박막을 증착 하기 위한 방법으로 이전부터 CVD (Chemical Vapor Deposition) 방법이 많이 사용되었고 지금까지도 가장 많이 사용되는 방법이다. CVD를 사용하여 $SiO_2$-like 필름의 증착은 전구체(precursor)로 Silane ($SiH_4$)을 사용하였으며, 플라즈마 발생 소스(source)로 열 혹은 전기장 등을 사용 하며 공정 시 압력 또한 대부분 저압 하에서 실시 하였다. 이와 같은 이전 CVD 방법의 문제는 사용되는 Silane 자체가 인체에 해로울 정도로 독성이 있으며 폭발성도 같이 가지고 있어 작업환경의 위험성이 높으며 열을 사용한 CVD의 경우 높은 공정 온도로 인해 증착 할 수 있는 대상이 제한 되어 지며 높은 열의 발생을 위해 많은 에너지의 소비가 필요하다. 저압 플라즈마를 사용한 CVD 는 공정상 높은 열의 발생이 일어나지 않아 기판 운용상 문제가 되지 않지만 저압 환경에서 해당 공정이 이루어기 때문에 인해 필수적으로 고가의 진공 챔버가 필수적이며 저압을 유지할 고가의 진공 펌프나 추가 장비들이 필요하게 된다, 또한 챔버 내에서 이루어지는 공정으로 인해 공정의 연속성이 떨어져 시잔비용 또한 많이 잡아 먹는다. 이러한 열 혹은 저압 플라즈마등을 사용한 공정의 단점을 해결하기 위해 여러 연구자들이 다양한 방법을 통해 연구를 하였다. 대기압 유전체 배리어 방전(AP-DBD: Atmospheric Pressure-Dielectric Barrier Discharge)을 사용한 폴리머 박막의 증착은 이전 전통적인 방법에 비해 낮은 장비 가격과 낮은 공정 온도 그리고 연속적인 공정 등의 장점이 있는 폴리머 박막 증착 방법 이다. 대기압 유전체 배리어 방전 공정 변수로 공급 전압 및 주파수 그리고 공급 전압의 영향, 전구체를 유전체 배리어 방전 전극으로 이동 시키기 위해 사용된 캐리어 가스의 종류 및 유량, 화학양론적 계수를 맞추기 위해 같이 포함되는 산소 가스의 유량, DBD 전극의 형태에 따른 증착 박막의 균일성 등 이 존재하며 이런 많은 변수 들에 대한 연구가 진행 되었지만 아직 이 대기압 DBD를 이용한 폴리머 박막의 증착에 대한 명확한 이해는 아직 완전 하다 할 수 없다. 본 연구에서는 이러한 대기압 DBD를 이용하여 폴리머 박막의 증착시 영향을 미치는 많은 공정 변수 등이 박막생성에 미치는 영향과 증착된 박막의 성질에 대한 연구를 진행 하였다.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.48-53
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• 2006

The purpose of this paper is to investigate the optimal condition of the SynGas production by reforming of propane using plasmatron. Plasma was generated by air and arc discharge. The effects of applied steam, $CO_2$ or Ni-catalyst on propane conversion, yield of hydrogen and $H_2/CO$ ratio as well as correlation of syngas were studied. When the variations of $O_2/C_3H_8$ flow ratio, $H_2O/C_3H_8$ flow ratio and $CO_2/C_3H_8$ flow ratio were $0.94{\sim}1.48,\;4.3{\sim}10\;and\;0.8{\sim}3.05$ respectively, Under the condition mentioned above, result of $H_2O/C_3H_8$ flow ratio was maximum $H_2$ concentration, or $28.2{\sim}31.6%$, and result of $H_2O/C_3H_8$ flow ratio with catalyst was minimum CO concentration or $6.6{\sim}7.1%$ and the ratio of hydrogen to carbon monoxide($H_2/CO$) were $3.89{\sim}4.86$.

• Polymer(Korea)
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• v.36 no.3
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• pp.357-363
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• 2012

Surface-modified poly(L-lactic acid) (PLLA) films and scaffolds were treated with plasma discharge in oxygen gas and subsequently subjected to $in$ $situ$ grafting of acrylic acid (AA) in order to increase the cell compatibility. The surface of AA-grafted PLLA was converted to hydroxyapatite (HA)-deposited PLLA in stimulated body fluid (SBF). After the samples were immersed in phosphate-buffered saline (PBS), fetal bovine serum (FBS), normal saline, or cell medium, the water contact angles were significantly reduced on the surface of HA-deposited PLLA. Chondrocyte and osteoblast showed a higher attachment and cell proliferation on HA-deposited surfaces and in particular, it was confirmed that chondrocyte was considerably influenced by HA. However, osteoblast showed better cell proliferation on the surfaces immersed in FBS, cell medium or HA-deposited surface. In addition, the cell proliferation in 3D scaffolds was much higher than that on film type, irrespective of chondrocyte and osteoblast. Therefore, such surface-modified PLLAs are expected to be useful as organic-inorganic hybrid scaffolds in the regeneration of cartilage and bone.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.433-433
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• 2012

As the requirement in patterning geometry continuously shrinks down, the termination of etch process at the exact time became crucial for the success in nano patterning technology. By virtue of real-time optical emission spectroscopy (OES), etch end point detection (EPD) technique continuously develops; however, it also faced with difficulty in low open ratio etching, typically in self aligned contact (SAC) and one cylinder contact (OCS), because of very small amount of optical emission from by-product gas species in the bulk plasma glow discharge. In developing etching process, one may observe that coupon test is being performed. It consumes costs and time for preparing the patterned sample wafers every test in priority, so the coupon wafer test instead of the whole patterned wafer is beneficial for testing and developing etch process condition. We also can observe that etch open area is varied with the number of coupons on a dummy wafer. However, this can be a misleading in OES study. If the coupon wafer test are monitored using OES, we can conjecture the endpoint by experienced method, but considering by data, the materials for residual area by being etched open area are needed to consider. In this research, we compare and analysis the OES data for coupon wafer test results for monitoring about the conditions that the areas except the patterns on the coupon wafers for real-time process monitoring. In this research, we compared two cases, first one is etching the coupon wafers attached on the carrier wafer that is covered by the photoresist, and other case is etching the coupon wafers on the chuck. For comparing the emission intensity, we chose the four chemical species (SiF2, N2, CO, CN), and for comparing the etched profile, measured by scanning electron microscope (SEM). In addition, we adopted the Dynamic Time Warping (DTW) algorithm for analyzing the chose OES data patterns, and analysis the covariance and coefficient for statistical method. After the result, coupon wafers are over-etched for without carrier wafer groups, while with carrier wafer groups are under-etched. And the CN emission intensity has significant difference compare with OES raw data. Based on these results, it necessary to reasonable analysis of the OES data to adopt the pre-data processing and algorithms, and the result will influence the reliability for relation of coupon wafer test and whole wafer test.

• Journal of the Korean Magnetics Society
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• v.22 no.3
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• pp.79-84
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• 2012

Nano-magnetic materials such as iron-nitrides have been actively studied as an alternative to the application of high density, high performance needs for next generation information storage and also alternative to the rare earth and neodymium magnet. $Fe_4N$ is the basic materials for magnetic storage media and is one of the important magnetic materials in focus because of its higher magnetic recording density and chemical stability. Single phase ${\gamma}^{\prime}-Fe_4N$ nanoparticles have been prepared by a PAD (Plasma Arc Discharge) method and nitriding in a $NH_3-H_2$ mixed gases at temperature, $400^{\circ}C$ for 4 hrs. Also $Fe_{17}Sm_2N_x$ powders were synthesized by nitriding after reduction/diffusion of $Fe_{17}Sm_2$ to compare the magnetic properties with nano-sized $Fe_4N$ particles. The saturation magnetization of $Fe_4N$ and $Fe_{17}Sm_2N_x$ were 149 and 117 emu/g, respectively, but the coercive force was considerably smaller than that of bulk or acicular $Fe_4N$.

• Korean Journal of Food Science and Technology
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• v.48 no.5
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• pp.525-529
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• 2016

Twenty-nine pepper products commercially available in the market were collected and investigate for contamination levels. Pepper products purchased from traditional markets had a degree of contamination of $10^6-10^7CFU/g$ aerobic bacteria, $10^4-10^5CFU/g$ Bacillus sp., and less than $10^2CFU/g$ yeast and molds. Organic pepper showed a degree of contamination of $10^4$ aerobic bacteria, $10^2-10^3$ Bacillus sp., and less than $10^1$ yeast and molds. Intense pulsed light (IPL) treatment of 10 min (1,000 V, 5 pps and 4 cm sample-to-lamp distance) showed a bacterial death rate of 1.45-1.55 log for whole peppers, and of 0.8-0.85 log for black and white pepper powder. The sterilization rate using IPL was higher than that using other non-thermal sterilization methods, such as ozone treatment or low-pressure discharge plasma sterilization, indicating that the IPL sterilization method may find potential application in the industry. However, further studies may need to be conducted to enhance the effect of sterilization.

• Journal of the Society of Disaster Information
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• v.18 no.3
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• pp.566-573
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• 2022

Purpose: This study attempted to verify the effectiveness of the application of air sterilizers in elementary schools at risk of group infection among vulnerable groups in order to address fears of new infectious diseases that have increased since the outbreak of Middle East Respiratory Syndrome (MERS) and Coronavirus infection-19 (COVID-19). Method: One air sterilizer was installed in each classroom, cafeteria, and bathroom of an elementary school in Seoul, and surface and air samples were collected at a distance of 2m from the air sterilizer, and the bacterial reduction effect was analyzed compared to the uninstalled control group. Result: The sterilization effect on the surface was less than 2log CFU/cm² in both the control group and the test group, and the test group showed 54 to 87% less general bacterial colony formation than the control group. In addition, the sterilization effect in the air differed depending on the location of the air sterilizer, and the wall installation showed a reduction effect of up to 91% compared to the control group, and the central installation showed a reduction effect of up to 93%. Conclusion: As a result of the study, it is expected that the prevention of infectious diseases can be increased by maintaining the current quarantine program in elementary schools that conduct regular disinfection while applying air sterilizers. In addition, it is considered desirable to facilitate the inflow of air into the air sterilizer.

• Electrical & Electronic Materials
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• v.12 no.7
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• pp.7-11
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• 1999

Fully sealed field emission display in size of 4.5 inch has been fabricated using single-wall carbon nanotubes-organic vehicle com-posite. The fabricated display were fully scalable at low temperature below 415$^{\circ}C$ and CNTs were vertically aligned using paste squeeze and surface rubbing techniques. The turn-on fields of 1V/${\mu}{\textrm}{m}$ and field emis-sion current of 1.5mA at 3V/${\mu}{\textrm}{m}$ (J=90${\mu}{\textrm}{m}$/$\textrm{cm}^2$)were observed. Brightness of 1800cd/$m^2$ at 3.7V/${\mu}{\textrm}{m}$ was observed on the entire area of 4.5-inch panel from the green phosphor-ITO glass. The fluctuation of the current was found to be about 7% over a 4.5-inch cath-ode area. This reliable result enables us to produce large area full-color flat panel dis-play in the near future. Carbon nanotubes (CNTs) have attracted much attention because of their unique elec-trical properties and their potential applica-tions [1, 2]. Large aspect ratio of CNTs together with high chemical stability. ther-mal conductivity, and high mechanical strength are advantageous for applications to the field emitter [3]. Several results have been reported on the field emissions from multi-walled nanotubes (MWNTs) and single-walled nanotubes (SWNTs) grown from arc discharge [4, 5]. De Heer et al. have reported the field emission from nan-otubes aligned by the suspension-filtering method. This approach is too difficult to be fully adopted in integration process. Recently, there have been efforts to make applications to field emission devices using nanotubes. Saito et al. demonstrated a car-bon nanotube-based lamp, which was oper-ated at high voltage (10KV) [8]. Aproto-type diode structure was tested by the size of 100mm $\times$ 10mm in vacuum chamber [9]. the difficulties arise from the arrangement of vertically aligned nanotubes after the growth. Recently vertically aligned carbon nanotubes have been synthesized using plasma-enhanced chemical vapor deposition(CVD) [6, 7]. Yet, control of a large area synthesis is still not easily accessible with such approaches. Here we report integra-tion processes of fully sealed 4.5-inch CNT-field emission displays (FEDs). Low turn-on voltage with high brightness, and stabili-ty clearly demonstrate the potential applica-bility of carbon nanotubes to full color dis-plays in near future. For flat panel display in a large area, car-bon nanotubes-based field emitters were fabricated by using nanotubes-organic vehi-cles. The purified SWNTs, which were syn-thesized by dc arc discharge, were dispersed in iso propyl alcohol, and then mixed with on organic binder. The paste of well-dis-persed carbon nanotubes was squeezed onto the metal-patterned sodalime glass throuhg the metal mesh of 20${\mu}{\textrm}{m}$ in size and subse-quently heat-treated in order to remove the organic binder. The insulating spacers in thickness of 200${\mu}{\textrm}{m}$ are inserted between the lower and upper glasses. The Y\ulcornerO\ulcornerS:Eu, ZnS:Cu, Al, and ZnS:Ag, Cl, phosphors are electrically deposited on the upper glass for red, green, and blue colors, respectively. The typical sizes of each phosphor are 2~3 micron. The assembled structure was sealed in an atmosphere of highly purified Ar gas by means of a glass frit. The display plate was evacuated down to the pressure level of 1$\times$10\ulcorner Torr. Three non-evaporable getters of Ti-Zr-V-Fe were activated during the final heat-exhausting procedure. Finally, the active area of 4.5-inch panel with fully sealed carbon nanotubes was pro-duced. Emission currents were character-ized by the DC-mode and pulse-modulating mode at the voltage up to 800 volts. The brightness of field emission was measured by the Luminance calorimeter (BM-7, Topcon).

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.395-403
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• 2006

It is known that $MgAl_2O_4$ has higher resistance to moisture than MgO, in humid ambient MgO is chemically unstable. It reacts very easily with moisture in the air. In this study, the characteristic of $MgAl_2O_4$ and $MgAl_2O_4/MgO$ layers as dielectric protection layers for AC- PDP (Plasma Display Panel) have been investigated and analysed in comparison for conventional MgO layers. MgO and $MgAl_2O_4$ films both with a thickness of $1000\AA$ and $MgAl_2O_4/MgO$ film with a thickness of $200/800\AA$ were grown on the Cu substrates using the electron beam evaporation. $1000\AA$ thick aluminium layers were deposited on the protective layers in order to avoid the charging effect of $Ga^+$ ion beam while the focused ion beam(FIB) is being used. We obtained sputtering yieds for the MgO, $MgAl_2O_4$ and $MgAl_2O_4/MgO$ films using the FIB system. $MgAl_2O_4/MgO$ protective layers have been found th show $24{\sim}30%$ lower sputtering yield values from 0.244 up to 0.357 than MgO layers with the values from 0.364 up to 0.449 for irradiated $Ga^+$ ion beam with energies ranged from 10 kV to 14 kV. And $MgAl_2O_4$ layers have been found to show lowest sputtering yield values from 0.88 up to 0.109. Secondary electron emission coefficient(g) using the ${\gamma}$- FIB. $MgAl_2O_4/MgO$ and MgO have been found to have similar g values from 0.09 up to 0.12 for indicated $Ne^+$ ion with energies ranged from 50 V to 200 V. Observed images for the surfaces of MgO and $MgAl_2O_4/MgO$ protective layers, after discharge degradation process for 72 hours by SEM and AFM. It is found that $MgAl_2O_4/MgO$ protective layer has superior hardness and degradation resistance properties to MgO protective layer.