• 한국전기전자재료학회논문지
• /
• 제13권9호
• /
• pp.770-775
• /
• 2000

A new photo-polymer material of the copoly (PM4Ch-ChMA), copoly (poly (4-methacryloyloxy)chalcone-cholesteryl methacrylate) for homeotropic alignment was synthesized and the electro-optical (EO) performance for the photo-aligned vertical-aligned (VA)-LC display (LCD) was studied. Good thermal stabilities of synthesized copolymer were obtained by TGA(Thermogravimetric Analysis) measurement. Good voltage-transmittance (V-T) and response time characteristics for the photo-aligned VA-LCD with polarized UV exposure in oblique direction($\theta$$_{i}$=30$^{\circ}$) on a copolymer-1 (2%) surfaces for 1 min were observed. but, light leakage in the off-state was observed. Therefore, we achieved excellent V-T and response time characteristics for the photo-aligned VA-LCD with UV exposure on a copolymer-3 (30%) surfaces for 3 min.n.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2009년도 추계학술대회 초록집
• /
• pp.155-155
• /
• 2009

The copper plating was deposited by pulse reverse current (PRC) method with additives. The all specimens were first immersted in 10% H2SO4 for 10 minutes, and then were rinsed with deionized water. The current densities of forward pulse were 400mA/$cm^2$, and those of reverse pulse were 1900mA/$cm^2$ and 100mA/$cm^2$. Results are compared for different additives for pulse plating conditions. When it added in Only CH4N2S (TU) or only C10H13NO3S (SVH), the effect of surface side growth of Cu was not different. But when it added in TU and SVH, surface side growth of Cu decreased. Polarization curves were measured from OCP to -0.7 V at a rate of 1mV/sec. Each specimen was observed under the PHENOM to see surface morphology.

• 한국지반환경공학회 논문집
• /
• 제9권6호
• /
• pp.13-19
• /
• 2008

사용 종료된 매립지의 환경적 영향에 따른 매립 후 변화에 대한 안전성 평가를 위하여 매립 폐기물의 성상 및 가스분석을 통한 연구의 결과는 매립폐기물의 물리적 성상분석의 유기성분이 29.72~63.84%이었고, 비닐 플라스틱류는 평균 32.88%로 가연성 물질의 대부분을 차지하고 있었으며, 침출수의 성분 중 $BOD_5$/CODcr비가 0.18정도로 나타났다. TS의 62.71%중 VS는 30.37%, FS는 32.34%로 FS의 비중이 약간 높게 나타났으며, 매립폐기물의 C/N비는 21.8로 나타났다. 매립지 주변 지표수는 BOD 10.7mg/g, SS의 경우 37.8mg/g, 대장균 31,157(MPN/$100m{\ell}$)로 나타났고, 지하수는 $COD_{Mn}$은 1.13-1.38mg/g, $NO_3-N$은 1.025-4.075mg/g로 나타났다. 침출수는 T-P 0.002-0.028mg/g, $NH_3-N$ 4.0-21.0mg/g로 나타났으며, BOD/CODcr비가 평균 0.18로 나타났다. 토양은 토양오염우려기준에 하회하는 농도분포를 나타내었으며, 매립가스의 $CH_4$와 $CO_2$가스는 각각 13.25%, 6.17%로 나타났고, $H_2S$나 CO가스는 검출되지 않았다. 지표 가스는 $CO_2$, $CH_4$, $H_2S$, CO가스 농도는 검출되지 않았으며, $NH_3$가스 농도는 평균 7.56ppm으로 분석되었다.

• Applied Biological Chemistry
• /
• 제49권2호
• /
• pp.149-152
• /
• 2006

산겨릅나무(A. tegmentosum)의 성분 연구를 위하여 줄기를 MeOH로 추출하여 $CH_2Cl_2$, n-BuOH 및 $H_2O$ 순으로 분획하였다. n-BuOH fraction에 대하여 silica gel과 RP-18 column chromatography를 행하여 2종의 화합물을 분리하였다. 이들 화합물의 구조는 spectral data를 문헌치와 비교하여 methyl gallate $4-O-{\beta}-D-glucoside(1)$와 salidroside(2)로 동정하였다. 이들 화합물은 산겨릅나무에서 처음으로 분리되었다.

• Natural Product Sciences
• /
• 제4권2호
• /
• pp.100-104
• /
• 1998

The antimutagenic activity of a methanol extract of roasted Cassia tora seed against aflatoxin $B_1(AFB_1)$ was demonstrated with the Salmonella typhimurium assay. The numbers of revertants per plate decreased significantly when this extract was added to the assay system using Salmonella typhimurium TA100 and or TA98. The MeOH extract was then sequentially partitioned with $CH_2Cl_2$, EtOAc, n-BuOH, and $H_2O$. The $CH_2Cl_2$ and n-BuOH fractions possessed antimutagenic activity, but the EtOAc and $H_2O$ fractions were inactive. Both the MeOH extract and its fractions were capable of inhibiting the indirect-acting mutagen $AFB_1$, suggesting that these fractions may prevent the metabolic activation of $AFB_1$, or scavenge the electrophilic intermediate capable of inducing mutations. Column chromatography using silica gel yielded pure alaternin from the $CH_2Cl_2$ a fraction, and adenosine and isorubrofusarin gentiobioside from the n-BuOH fraction. Alaternin and isorubrofusarin gentiobioside demonstrated significant antimutagenic activities.

• Journal of Animal Science and Technology
• /
• 제65권2호
• /
• pp.459-472
• /
• 2023

Korea is currently developing country-specific emission factors to support the 2050 zero-carbon campaign. Dairy cattle represent one of the largest livestock industries in Korea, and the industry is estimated to continue increasing because of an increase in milk demand. However, country-specific emission factors for dairy cattle are currently only available for calculating methane (CH₄) emissions from enteric fermentation. Two experiments were conducted to evaluate CH₄ and nitrous oxide (N₂O) fluxes from sawdust-bedded barn in dairy cow and steer, as well as dairy cattle manure composting lots. The greenhouse gas (GHG) fluxes were quantified using the open-chamber method and gas chromatography. CH₄ fluxes from steer, dairy cow, and manure compost were 27.88 ± 5.84, 36.12 ± 10.85, and 259.44 ± 61.78 ㎍/head/s, respectively. N₂O fluxes from steer, dairy cow, and manure compost were 14.04 ± 1.27, 4.11 ± 1.57, and 3.97 ± 1.08 ㎍/head/s, respectively. The result of this study can be used to construct country-specific data for GHG emissions from manure management. Thus, the application of mitigation strategies can be prioritized based on the GHG profile and targeted source.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.167-167
• /
• 2011

Magnetic random access memory (MRAM) is one of the prospective semiconductor memories for next generation. It has the excellent features including nonvolatility, fast access time, unlimited read/write endurance, low operating voltage, and high storage density. MRAM consists of magnetic tunnel junction (MTJ) stack and complementary metal-oxide semiconductor (CMOS). The MTJ stack is composed of various magnetic materials, metals, and a tunneling barrier layer. For the successful realization of high density MRAM, the etching process of magnetic materials should be developed. Among various magnetic materials, FePt has been used for pinned layer of MTJ stack. The previous etch study of FePt magnetic thin films was carried out using $CH_4/O_2/NH_3$. It reported only the etch characteristics with respect to the variation of RF bias powers. In this study, the etch characteristics of FePt thin films have been investigated using an inductively coupled plasma reactive ion etcher in various etch chemistries containing $CH_4$/Ar and $CH_4/O_2/Ar$ gas mixes. TiN thin film was employed as a hard mask. FePt thin films are etched by varying the gas concentration. The etch characteristics have been investigated in terms of etch rate, etch selectivity and etch profile. Furthermore, x-ray photoelectron spectroscopy is applied to elucidate the etch mechanism of FePt thin films in $CH_4$/Ar and $CH_4/O_2/Ar$ chemistries.

• Animal Bioscience
• /
• 제37권3호
• /
• pp.481-491
• /
• 2024

Objective: This study determined fermentation characteristics of commonly used feedstuffs, especially tropical roughages, for dairy cattle in Southeast Asia. This information is considered relevant in the context of the observed low milk fat content and milk production in Southeast Asia countries. Methods: A total of 29 feedstuffs commonly used for dairy cattle in Vietnam and Thailand were chemically analysed and subjected to an in vitro gas production (GP) test. For 72 h, GP was continuously recorded with fully automated equipment and methane (CH₄) was measured at 0, 3, 6, 9, 12, 24, 30, 36, 48, 60, and 72 h of incubation. A triphasic, nonlinear, regression procedure was applied to analyse GP profiles while a monophasic model was used to obtain kinetics related to CH₄ production. Results: King grass and VA06 showed a high asymptotic GP related to the soluble- and non-soluble fractions (i.e. A1 and A2, respectively) and had the highest acetate to propionate ratio in the incubation fluid. The proportion of CH₄ produced (% of GP at 72 h) was found to be not different (p>0.05) between the various grasses. Among the selected preserved roughages (n = 6) and whole crops (n = 4), sorghum was found to produce the greatest amount of gas in combination with a relatively low CH₄ production. Conclusion: Grasses belonging to the genus Pennisetum, and whole crop sorghum can be considered as suitable ingredients to formulate dairy rations to enhance milk fat content in Vietnam/Thailand.

• 대한화학회지
• /
• 제55권2호
• /
• pp.199-203
• /
• 2011

일차원 수소결합형 배위고분자 $[Cu^{II}(C_{13}H_{17}N_3OBr)(C_8H_5O_4)]{\cdot}2H_2O.CH_3OH$을 합성하여 단결정 X-선 회절 연구로 특성을 규명하였다. 단량체 단위는 사각평면의 중심 $Cu^{II}$를 갖고 있다. 네개의 배위자리 중 세자리는 $N_2O$-주개 세트를 갖는 Schiff 염기형 리간드 (4-bromo-2-[(2-piperazin-1-yl-ethylimino)-methyl]-phenol)가 차지하고, 네 번째 자리는 옆에 있는 테레프탈레이트 단위의 산소 원자가 차지한다. 두개의 인접한 중성분자는 분자간 N-H---O 및 O-H---N 수소결합에 의해 연결되어 이합체 쌍을 형성한다. 각 이합체 쌍은 불연속적인 물 및 메탄올 분자에 의해 수소결합으로 다시 연결되어 일차원 초분자 네트워크를 형성한다.

• Advances in environmental research
• /
• 제9권2호
• /
• pp.123-133
• /
• 2020

A time series dataset was conducted to ascertain the effect of water table on the variability in and emission of CH₄ and CO₂ concentrations at a closed landfill site. An in-situ data of methane/carbon dioxide concentrations and environmental parameters were collected by means of an in-borehole gas monitor, the Gasclam (Ion Science, UK). Linear regression analysis was used to determine the strength of the correlation between ground-gas concentration and water table. The result shows CH₄ and CO₂ concentrations to be variable with strong negative correlations of approximately 0.5 each with water table over the entire monitoring period. The R² was slightly improved by considering their concentration over single periods of increasing and decreasing water table, single periods of increasing water table, and single periods of decreasing water table; their correlations increased significantly at 95% confidence level. The result revealed that fluctuations in groundwater level is the key driving force on the emission of and variability in groundgas concentration and neither barometric pressure nor temperature. This finding further validates the earlier finding that atmospheric pressure - the acclaimed major control on the variability/migration of CH₄ and CO₂ concentrations on contaminated sites, is not always so.