• 한국유기농업학회지
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• 제28권4호
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• pp.579-589
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• 2020

고추역병 다발생 포장에서 녹비작물인 호밀재배에 따른 토양환경 변화와 고추역병 경감 효과를 조사하였다. 토양 물리성을 분석한 결과에서는 호밀재배에서 용적밀도와 공극률이 증가하였다. 또한, 토양 삼상의 분포는 고상에서는 관행재배와 차이가 없었으나, 기상은 관행재배 보다 증가하고 액상은 감소하였다. 토양 내 인지질 지방산을 추출하여 지표 지방산으로 분석한 미생물 군락의 상대밀도는 호밀재배에서 유의성 있게 증가하였으며, 호기성균/혐기성균의 비율의 비율도 호밀재배에서 높게 나타났다. 환경스트레스 지표인 포화지방산/불포화지방산 비율과 cyclo-지방산/전구체 비율은 호밀재배가 관행재배 보다 낮아 토양환경이 개선 된 것으로 나타났다. 호밀재배에 따른 고추역병의 경감효과를 조사한 결과 호밀재배가 관행재배 보다 30.7% 낮은 발병률을 나타냈다. 이상의 결과를 요약해볼 때, 고추역병 다발생 포장에서 녹비작물인 호밀재배는 토양환경을 개선하고 고추역병 발병을 감소시킬 것으로 사료된다.

• 한국대기환경학회지
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• 제34권5호
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• pp.639-650
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• 2018

Identification of the major sources contributing to PM is of importance in order to understand their quantitative contributions to atmosphere. In the viewpoint of the meat cooking in Korea, only a few analyses of organic molecular markers have been conducted due to analytical difficulties. In this study, ten different parts of meat (i.e., blade shoulder, belly, and arm shoulder of pork; ribeye roll, top blade muscle, and short plate of beef; leg quarter, breast, and wing of chicken; duck; mackerel) were pyrolyzed to generate the cooked PM using an electronic heating plate. Generated PM were collected by the pyrolysis sampling system to identify total carbon (TC) using a carbon analyzer and cholesterol using a Liquid chromatography tandem-mass spectrometry (LC-MSMS) based on fragmentor voltage (FV), precursor ion, collision energy, product ion. In addition, oxydative potential (OP) analysis using dithiothreitol (DTT) method were discussed to investigate the toxicity relates. Highly correlated pairwise scatterplots between the cholesterol and TC indicate that oxydative potential was highly associated with different parts of meat. This study provides insight into the meat cooking components of PM, which could be drivers of the oxidative potential relates.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.19-19
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• 2002

Perovskite-type titanate dielectrics have attracted much attention in memory devices such as DRAMs or FeRAMs due to their high dielectric constants. However, low volatility of the Ba, Sr, Pb or Zr precursors with only thd ligands has limitations in obtaining high quality thin films by liquid source metal organic chemical vapor deposition (LS-MOCVD) processes. To improve the volatility of these precursors, many attempts have been made such as adding polyether ligands to satisfy the coordinative saturation. We report the synthesis of new precursors Ba(thd)₂(tmeea) and Sr(thd)₂(tmeea), where tmeea = tris[2-(2-methoxyethoxy)ethyl]amino, and LS-MOCVD of barium strontium titanate (BSTO) thin films using these precursors. Due to increased basicity of amines compared with ethers, it is expected that the nitrogen-donor ligand will make a strong bond to a metal than an analogous oxygen-donor ligand, consequently improving the volatility and thermal behavior of these precursors. Thin films of BSTO were grown on Pt(111)/SiO₂/Si(100) substrates by LS-MOCVD using a cocktail source consisting of the conventional Ti precursor Ti(thd)₂(O/sup i/Pr), and these new Ba and Sr precursors. As-grown films were characterized by XPS, SEM, XRD, XRF, and C-V and I-V measurements. BSTO films grown at 420℃ were stoichiometric barium strontium titanate with very smooth surface morphology and their dielectric constants were found to be as targe as 450. Dependence of the composition, microstructure and the electrical properties of the BSTO films on the growth temperature, annealing temperature, working pressure, and the composition of the cocktail source will be discussed.

• 한국산학기술학회논문지
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• 제1권1호
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• pp.37-42
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• 2000

유기금속 화학기상증착기술에 의해 폴리이미드 기판과 질화티탄 기판 위에 구리박막을 형성하였다. 구리박막을 화학기상증착기술에 의해 형성하면 종래의 물리적증착기술에 비하여 증착속도가 빠르고 층덮힘 성질이 좋아 산업체의 제품생산 응용에서 많은 장점이 있다. 이 장점은 제품의 생산성과 신뢰성에 영향을 미친다. 기판의 온도와 구리전구체 증기압력 조건을 변화시키며 반복실험을 실시하였으며, 시편에 따라서는 전기적 성질 향상을 위하여 후속 열처리를 수행하였다. 형성된 구리박막의 미세구조는 전자현미경으로 관찰하였으며, 전기비저항은 4점 프로브를 이용하여 측정하였다. 질화티탄을 기판으로 사용한 경우 구리박막에서는 섭씨 180도의 기판온도에서 만들어진 시편에서 가장 좋은 전기적 성질이 측정되었다. 한편, 폴리이미드 기판을 사용한 경우, 기상과 액상의 혼합상태 전구체를 이용하여 250 nm/min의 매우 높은 증착속도를 얻을 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.362-362
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• 2014

Atomic layer deposition (ALD) can be regarded as a special variation of the chemical vapor deposition method for reducing film thickness. ALD is based on sequential self-limiting reactions from the gas phase to produce thin films and over-layers in the nanometer scale with perfect conformality and process controllability. These characteristics make ALD an important film deposition technique for nanoelectronics. Tantalum pentoxide ($Ta_2O_5$) has a number of applications in optics and electronics due to its superior properties, such as thermal and chemical stability, high refractive index (>2.0), low absorption in near-UV to IR regions, and high-k. In particular, the dielectric constant of amorphous $Ta_2O_5$ is typically close to 25. Accordingly, $Ta_2O_5$ has been extensively studied in various electronics such as metal oxide semiconductor field-effect transistors (FET), organic FET, dynamic random access memories (RAM), resistance RAM, etc. In this experiment, the variations of chemical and interfacial state during the growth of $Ta_2O_5$ films on the Si substrate by ALD was investigated using in-situ synchrotron radiation photoemission spectroscopy. A newly synthesized liquid precursor $Ta(N^tBu)(dmamp)_2$ Me was used as the metal precursor, with Ar as a purging gas and $H_2O$ as the oxidant source. The core-level spectra of Si 2p, Ta 4f, and O 1s revealed that Ta suboxide and Si dioxide were formed at the initial stages of $Ta_2O_5$ growth. However, the Ta suboxide states almost disappeared as the ALD cycles progressed. Consequently, the $Ta^{5+}$ state, which corresponds with the stoichiometric $Ta_2O_5$, only appeared after 4.0 cycles. Additionally, tantalum silicide was not detected at the interfacial states between $Ta_2O_5$ and Si. The measured valence band offset value between $Ta_2O_5$ and the Si substrate was 3.08 eV after 2.5 cycles.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.377-377
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• 2012

Microprocessor technology now relies on copper for most of its electrical interconnections. Because of the high diffusivity of copper, Atomic layer deposition (ALD) $TaN_x$ is used as a diffusion barrier to prevent copper diffusion into the Si or $SiO_2$. Another problem with copper is that it has weak adhesion to most materials. Strong adhesion to copper is an essential characteristic for the new barrier layer because copper films prepared by electroplating peel off easily in the damascene process. Thus adhesion-enhancing layer of cobalt is placed between the $TaN_x$ and the copper. Because, cobalt has strong adhesion to the copper layer and possible seedless electro-plating of copper. Until now, metal film has generally been deposited by physical vapor deposition. However, one draw-back of this method is poor step coverage in applications of ultralarge-scale integration metallization technology. Metal organic chemical vapor deposition (MOCVD) is a good approach to address this problem. In addition, the MOCVD method has several advantages, such as conformal coverage, uniform deposition over large substrate areas and less substrate damage. For this reasons, cobalt films have been studied using MOCVD and various metal-organic precursors. In this study, we used $C_{12}H_{10}O_6(Co)_2$ (dicobalt hexacarbonyl tert-butylacetylene, CCTBA) as a cobalt precursor because of its high vapor pressure and volatility, a liquid state and its excellent thermal stability under normal conditions. Furthermore, the cobalt film was also deposited at various $H_2/NH_3$ gas ratio(1, 1:1,2,6,8) producing pure cobalt thin films with excellent conformality. Compared to MOCVD cobalt using $H_2$ gas as a reactant, the cobalt thin film deposited by MOCVD using $H_2$ with $NH_3$ showed a low roughness, a low resistivity, and a low carbon impurity. It was found that Co/$TaN_x$ film can achieve a low resistivity of $90{\mu}{\Omega}-cm$, a low root-mean-square roughness of 0.97 nm at a growth temperature of $150^{\circ}C$ and a low carbon impurity of 4~6% carbon concentration.

• 한국산업보건학회지
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• 제21권3호
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• pp.156-161
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• 2011

Objectives: Tetrahydrofuran (THF) is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. THF has been used as a solvent and a precursor for various syntheses of polymers. However, THF is known to irritate to the eyes, skin and mucus membranes. Overexposure by inhalation, ingestion or skin contact may produce nausea, dizziness, headaches, respiratory irritation and possible skin burns. The purpose of this study is to evaluate of the worker exposure and characteristics of workers in the workplaces that use or manufacture THF. Methods: Sixteen factories in Korea, which manufacture or use THF, were selected for this study and a total of 130 air samples including 104 time-weighted average (TWA) samples and 26 short-term exposure limit (STEL) samples, were collected. Air samples were collected with charcoal tube (100mg/50mg) and analyzed by gas chromatograph/flame ionization detector(GC/FID). Results: The TWA concentration of THF was 16.05ppm (GM) at PS script printing, 2.32ppm (GM) at PVC stabilizer, 1.03ppm (GM) at Lithium triethylborohydride, 0.63ppm (GM) at Polytetramethylene ether glycol(PTMEG), 0.42ppm (GM) at Manufacturing THF, 0.13ppm (GM) at Glue and 0.12ppm (GM) at synthetic rubber/resins. Two out of sampes for PS script printing exceeded 50ppm as 8-hour exposure limit of MOEL. The short term exposure to THF was 54.77ppm (GM) at PS script printing, 17.10ppm (GM) at PTMEG, 13.76ppm (GM) at Manufacturing THF, 2.86ppm (GM) at Lithium triethylborohydride, 0.87ppm (GM) at synthetic rubber/resins and 0.13ppm (GM) Glue. We found that the highest exposure process for both the TWA and STEL samples was PS script process. Two samples exceeded 100ppm as short term exposure limit of Ministry of Employment and Labor(MOEL). Conclusions: Characteristic of STEL concentration for THF is considerably different from TWA concentration in workplaces because workers could exposure high concentration of THF in a moment when they work irregularly schedule. So exposure controls for momentary works have to be prepared, and considered the skin absorption and inhale of THF.