• Journal of Korean Society for Atmospheric Environment
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• v.18 no.2
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• pp.113-126
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• 2002

This study was carried out to evaluate the temporal (daily, weekly, and seasonal) variations of volatile organic compounds (VOCs) concentrations at a road-side site in a heavy-traffic central area of Metropolitan Taegu. Ambient air sampling was undertaken continuously for 14 consecutive days in each of four seasons from the spring of 1999 to the winter of 2000. The VOC samples were collected using adsorbent tubes, and were determined by thermal desorption coupled with GC/MS analysis. A total of 10 aromatic VOCs of environmental concern were determined, including benzene, toluene, ethylbenzene, m＋p-xylenes, styrene, o-xylene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, and naphthalene. Among 10 target VOCs, the most abundant compounds appeared to be toluene (1.5 ∼ 102 ppb) and xylenes (0.1 ∼ 114 ppb), while benzene levels were in the range of 0.3 ∼6 ppb. It was found that the general trends of VOC levels were significantly dependent on traffic conditions at the sampling site since VOC concentrations were at their maximum during rush hours (AM 7∼9 and PM 7 ∼9). However, some VOCs such as toluene, xylenes, and ethylbenzene were likely to be affected by a number of unknown sources other than vehicle exhaust, being attributed to the use of paints, and/or the evaporation of solvents used nearby the sampling site. In some instances, extremely high concentrations were found for these compounds, which can not be explained solely by the impact of vehicle exhaust. The results of this study may be useful for estimating the relative importance of different emission sources in large urban areas. Finally, it was suggested that the median value might be more desirable than the arithmetic mean as a representative value for the VOC data group, since the cumulative probability distribution (n=658) does not follow the normal distribution pattern.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.3-5
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• 2008

An increase in oil and gas plants caused by development of process industry have brought into the increase in use of flammable and toxic materials in the complex process under high temperature and pressure. There is always possibility of fire and explosion of dangerous chemicals, which exist as raw materials, intermediates, and finished goods whether used or stored in the industrial plants. Since there is the need of efforts on disaster damage reduction or mitigation process, we have been conducting a research to relate explosion model on the background of real 3D terrain model. By predicting the extent of damage caused by recent disasters, we will be able to improve efficiency of recovery and, sure, to take preventive measure and emergency counterplan in response to unprepared disaster. For disaster damage prediction, it is general to conduct quantitative risk assessment, using engineering model for environmental description of the target area. There are different engineering models, according to type of disaster, to be used for industry disaster such as UVCE (Unconfined Vapour Cloud Explosion), BLEVE (Boiling Liquid Evaporation Vapour Explosion), Fireball and so on, among them, we estimate explosion damage through UVCE model which is used in the event of explosion of high frequency and severe damage. When flammable gas in a tank is released to the air, firing it brings about explosion, then we can assess the effect of explosion. As 3D terrain information data is utilized to predict and estimate the extent of damage for each human and material. 3D terrain data with synthetic environment (SEDRIS) gives us more accurate damage prediction for industrial disaster and this research will show appropriate prediction results.

• Fire Science and Engineering
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• v.25 no.3
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• pp.91-98
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• 2011

This study is about fire resistance performance of wood framed lightweight wall including a middle lintel as a traditional wall form in Korea. The target wall is non-loadbearing system which constructed with $38{\times}89$ mm ($2"{\times}4"$) wood frame and fireproof gypsum board covering, including a middle lintel made of $150{\times}150$ mm section glue-laminated timber. As a test results, all specimens have showed fire resistant performance over 90 minutes and tests were maintained until flame occuring on Specimen-l, 2, 3 at 91 min, 97 min and 98 min respectively. Fire resistance of the heat side gypsum board was 45 minutes and charring rate of middle lintel was equivalant with that of usual timber. The wood stud inside wall system showed relatively quick combution characteristic when exposed to high temperature with no temperature rising delaying time caused by moisture evaporation because of the dehydration preceded during the early period of fire side gypsum board resist to heat.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.612-616
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• 2009

Transparent conductive oxide (TCO) films have been widely used in the field of flat panel display industry. Transparent conductive indium zinc oxide (IZO) thin films with excellent chemical stability have attracted much attention as an alternative material for indium tin oxide (ITO) films. In this study, using a $In_2O_3$ and ZnO powder mixture with a ratio of 90 : 10wt% as a target, IZO films were prepared on polynorbornene (PNB) substrates by electron beam evaporation. The effect of substrate temperature and $O_2$ introduction flow rate were investigated in terms of electrical and optical properties of deposited IZO films. The best electrical and optical properties we obtained from this study were sheet resistance value of $5.446{\times}10^2{\Omega}/{\boxempty}$ and optical transmittance of 87.4% at 550 nm at $O_2$ introduction flow rate of 4 sccm, deposition rate of $2{\AA}$/sec, thickness of 1000 $\AA$ and substrate temperature of $150^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.103-103
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• 1999

CeO2 는 cubic 구조의 일종인 CeF2 구조를 가지며 격자 상수가 0.541nm로 Si의 격자 상수 0.543nm와 거의 비슷하여 Si과의 부정합도가 0.35%에 불과하여 CeO2를 Si 기판 위에 에피택셜하게 성장시킬 수 있는 가능성이 크다. 따라서 SOI(Silicon-On-Insulator) 구조의 실현을 위하여 Si 기판위에 CeO2를 에피택셜하게 성장시키려는 많은 노력이 있었다. 또한 CeO2 는 열 적으로 대단히 안정된 물질로서 금속/강유전체/반도체 전계효과 트랜지스터(MFSFET : metal-ferroelectric-semiconductor field effect transistor)에서 ferroelectric 박막과 Si 기판사이에 완충층으로 사용되어 강유전체의 구성 원자와 Si 원자들간의 상호 확산을 방지함으로써 경계면의 특성을 향상시기키 위해 사용된다. e-beam evaporation와 laser ablation에 의한 Si 기판 위의 CeO2 격자 성장에 관한 많은 보고서가 있다. 이 방법들은 대규모 생산 공정에서 사용하기 어려운 반면 RF-magnetron sputtering은 대규모 반도체 공정에 널리 쓰인다. Sputtering에 의한 Si 기판위의 CeO2 막의 성장에 관한 보고서의 수는 매우 적다. 이 논문에서는 Ce target을 사용한 reactive rf-magnetron sputtering에 의해 Si(100) 과 Si(111) 기판위에 성장된 CeO2 의 구조 및 전기적 특성을 보고하고자 한다. 주요한 증착 변수인 증착 power와 증착온도, Seed Layer Time이 성장막의 결정성에 미치는 영향을 XRD(X-Ray Diffractometry) 분석과 TED(Transmission Electron Diffration) 분석에 의해 연구하였고 CeO2 /Si 구조의 C-V(capacitance-voltage)특성을 분석함으로써 증차된 CeO2 막과 실리콘 기판과의 계면 특성을 연구하였다. CeO2 와 Si 사이의 계면을 TEM 측정에 의해 분석하였고, Ce와 O의 화학적 조성비를 RBS에 의해 측정하였다. Si(100) 기판위에 증착된 CeO2 는 $600^{\circ}C$ 낮은 증착률에서 seed layer를 하지 않은 조건에서 CeO2 (200) 방향으로 우선 성장하였으며, Si(111) 기판 위의 CeO2 박막은 40$0^{\circ}C$ 높은 증착률에서 seed layer를 2분이상 한 조건에서 CeO2 (111) 방향으로 우선 성장하였다. TEM 분석에서 CeO2 와 Si 기판사이에서 계면에서 얇은 SiO2층이 형성되었으며, TED 분석은 Si(100) 과 Si(111) 위에 증착한 CeO2 박막이 각각 우선 방향성을 가진 다결정임을 보여주었다. C-V 곡선에서 나타난 Hysteresis는 CeO2 박막과 Si 사이의 결함때문이라고 사료된다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.35-35
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• 2001

agnesium Oxide (MgO) with a NaCI structure is well known to exhibit high secondary electron emission, excellent high temperature chemical stability, high thermal conductance and electrical insulating properties. For these reason MgO films have been widely used for a buffer layer of high $T_c$ superconducting and a protective layer for AC-plasma display panels to improve discharge characteristics and panel lifetime. Up to now MgO films have been synthesized by lE-beam evaporation, Molecular Beam Epitaxy (MBE) and Metalorganic Chemical Vapor Deposition (MOCVD), however there have been some limitations such as low film density and micro-cracks in films. Therefore magnetron sputtering process were emerged as predominant method to synthesis high density MgO films. In previous works, we designed and manufactured unbalanced magnetron source with high power density for the deposition of high quality MgO films. The magnetron discharges were sustained at the pressure of O.lmtorr with power density of $110W/\textrm{cm}^2$ and the maximum deposition rate was measured at $2.8\mu\textrm{m}/min$ for Cu films. In this study, the syntheses of MgO films were carried out by unbalanced magnetron sputtering with various $O_2$ partial pressure and specially target power densities, duty cycles and frequency using pulsed DC power supply. And also we investigated the plasma states with various $O_2$ partial pressure and pulsed DC conditions by Optical Emission Spectroscopy (OES). In order to confirm the relationships between plasma states and film properties such as microstructure and secondary electron emission coefficient were analyzed by X-Ray Diffraction(XRD), Transmission Electron Microscopy(TEM) and ${\gamma}-Focused$ Ion Beam (${\gamma}-FIB$).

• Journal of the Korean Institute of Landscape Architecture
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• v.41 no.5
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• pp.68-77
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• 2013

Change in the Global Climate causes flood, drought, heavy snow, and rainfall patterns in the Korean Peninsula. A variety of alternatives related to climate change are considered. The foreign researchers are interested in Low Impact Development(LID); the utilization of water resources and eco friendly development, over 10 years ago. The research and development of related technology has been advanced to apply LID techniques in order to develop several projects in the country. However, sharing of technology or system that can be used easily in the private sector is insufficient. The performance of the elements of LID Technology has not been fully agreed. LID elements of this technology are easy to apply to Apartment complex. The elements are classified technology. The infiltration of elements performs the functions of apartment complex landscaping space technology applied to the target. The water cycle simulation(SWMM 5.0) and technology the implementation of the effectiveness is also verified. For this purpose, three different places in apartment complex to target by SWMM5.0 U.S. EPA conducted utilizing simulated rainfall and applying LID techniques before and after the simulated water cycle (infiltration, surface evaporation, and surface runoff) were conducted. The importance of green space in the LID techniques of quantitative and qualitative storm water control as well as the role of Apartment Housing is to promote Amenity. Remember that the physical limitations of apartment complex and smooth water circulation system for the application of LID integrated management techniques should be applied. To this end, landscapes, architecture, civil engineering, environmental experts for technical consilience between the Low Impact Development efforts are required.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.66-66
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• 2008

본 연구에서는 ITO/Ag/ITO 다층 박막을 유기발광소자와 플렉시블 광전소자의 전극으로 적용하기 위하여 선형 대항 타겟 스퍼터(Linear facing target sputter) 시스템을 이용하여 성막하였고, ITO/Ag/ITO 다층박막의 전기적, 광학적, 구조적 특성을 분석하였다. 선형 대항 타겟 스퍼터 시스템은 강한 일방항의 자계와 타겟에 걸린 음극에 의해 전자의 회전, 왕복 운동이 가능해 마주보는 두 ITO 타겟 사이에 고밀도의 플라즈마를 구속 시켜 플라즈마 데미지 없이 산화물 박막을 성막시킬 수 있는 장치이다. 대항 타겟 스퍼터 시스템을 이용하여 성막한 ITO 전극을 DC power, working pressure, Ar/O2 ratio 에 따른 특성을 각각 분석하였다. glass 기판위에 최적화된 ITO 전극을 bottom layer로 두고, bottom ITO layer 위에 thermal evaporation 을 이용하여 Ag 박막을 6~20nm의 조건에 따라 두께를 다르게 성막하고, Ag 박막을 성막한 후에 다시 bottom ITO 전극과 같은 조건으로 ITO 전극을 top layer로 성막 하였다. 두 비정질의 ITO 전극 사이에 매우 앓은 Ag 박막을 성막 함으로 해서 glass 기판위에 ITO/Ag/ITO 다층 박막전극은 매우 낮은 저항과 높은 투과도를 나타낸다. ITO/Ag/ITO 박막의 전기적 광학적 특성을 보기 위해 hall measurement와 UV/visible spectrometer 분석을 각각 진행하였다. ITO/Ag/ITO 다층 박막 전극이 매우 얇은 두께임에도 불구하고 $4\Omega$/sq.의 낮은 면저항과 85%의 높은 투과도를 나타내는 이유는 ITO/Ag/ITO 전극 사이에 있는 Ag층의 표면 플라즈몬 공명 (SPR) 현상으로 설명할 수 있다. ITO/Ag/ITO 전극의 Ag의 거동을 분석 하기위해 FESEM분석과 synchrotron x-ray scattering 분석을 하였다. ITO/Ag/ITO 전극의 Ag층이 islands의 모양에서 연속적으로 연결되는 변화과정 중에 SPR현상이 일어남을 알 수 있다. 여기서, 대항 타겟 스퍼터 시스템을 이용하여 성막한 ITO/Ag/ITO 다층박막을 OLED 또는 inverted OLEDs의 top 전극으로의 적용 가능성을 보이고 있다.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.78.2-78.2
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• 2010

Cu(In,Ga)Se2 (CIGS)박막태양전지는 간단한구조와 가격경쟁력 및 고효율화 가능성에 대한 기대감에 의해 많은 연구가 수행되어오고 있다. 특히 높은 흡수계수와 적절한 밴드갭, 큰 결정크기와 같은 물질의 특성들이 장점으로 작용하고 있기 때문이다. 또한 CIGS박막태양전지는 다른 태양전지에 비해 광열화가 적다는 장점도 가지고 있다. CIGS 박막은 CuInSe2내의 In 사이트에 Ga을 도핑함으로서 형성이 되는데 그때의 밴드갭은 약 1.4eV이며 이를 형성하기 위해 많은 방법들이 제안되고 있는데, CIGS박막 형성 시 가장 중요시 여겨야 될 인자는 구성원소로부터 최적화된 조성비를 찾는 것이다. 이러한 관점에서 볼때 evaporation법이나 sputtering법같은 진공방식의 공정법이 비진공방식에 비해 최적의 조성비를 찾는 것이 수월할 것으로 생각된다. selenization을 하기전에, 동시증착이나 다층박막형성을 통해 Cu-In-Se의 조합이 일반적으로 이루어진다. 어떤방법이든 Se의 부가적인 공급이 이루어지는데 시작 전구체의 조합에서 그 해법을 제시하는 것에 대한 논의가 많이 부족한 현실로서, CuInSe2의 단일전구체에 의한 박막형성과 특성평가에 대해 구체적인 논의가 필요하다. 본 실험에서는 Cu-In-Se 전구체를 CuInSe2 단일 타겟에서부터 RF 마그네트론 스퍼터링법을 이용하여 박막증착을 하여 Se의 Rapid Thermal Process(RTA)법을 통해 Se이 순차적으로 공급되었다. 이때 형성되는 박막의 태양전지 흡수층 적용을 위한 광학적, 전기적 및 구조적에 대한 논의된다. Soda lime glass(SLG)와 Corning 1737 유리를 기판으로 하여 아세톤-에탄올을 이용, 초음파세척을 실시하였다. 스퍼터 공정을 하기전에 흡착된 물분자를 제거하기 위하여 약 30분간 $120^{\circ}C$로 열을 가해주었으며, 공정을 위한 총 아르곤 가스의 양은 약 50sccm이며 이때의 공정압력은 20mtorr로 고정하였다. 우선 RF power와 기판온도에 따른 단일전구체 형성을 관찰하기 위하여 각각 30~80W, RT~$400^{\circ}C$로 변화를 주어 박막을 형성한 후 모든 sample에 대하여 $500^{\circ}C$분위기에 effusion cell을 이용하여 Se 분위기에서 결정화를 실시하였다. 샘플의 두께는 Surface profiler로 측정하였고 단면은 전자주사현미경으로 관찰되었다. 동시에 SEM이미지를 통하여 morphology와 grain size 및 EDX를 통하여 조성분석을 하였다. 밴드갭, 투과율 및 흡수계수는 UV-VIS-NIR분광분석법을 통하여 수행되었으며, 전기적 특성분석을 위해 4-point-probe와 Hall effect측정을 수행하였다. 공정변수에 따른 단일타겟으로 얻어 결정화된 CuInSe2박막의 자세한 결과와 논의에 대하여 발표한다.

• Journal of the Korean Electrochemical Society
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• v.3 no.1
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• pp.44-48
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• 2000

Amorphous $V_2O_5$ cathode thin films were prepared by DC-magnetron sputtering at room temperature and the thin film rechargeable lithium batteries were fabricated with the configuration of $V_2O_5/LIPON/Li$ using sequential ex-situ thin film deposition techniques. The electrochemical characteristics of $V_2O_5$ cathode materials Prepared at 80/20 of $Ar/O_2$ ratio showed high capacity and cycling behaviors by half cell test. LIPON solid electrolytes films were prepared by RF-magnetron sputtering using the self-made $Li_3PO_4$ target in pure $N_2$ atmosphere, and it was very stable for lithium contact in the range of 1.2-4.0 V vs. Li. Metallic lithium were deposited on LIPON electrolyte by thermal evaporation methode in dry room. Vanadium oxide based full cell system showed the initial discharge capacity of $150{\mu}A/cm^2{\mu}m$ in the range of $1.2\~3.5V$.