• 멤브레인
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• 제14권4호
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• pp.312-319
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• 2004

졸겔법에 의해 Si(OC$_2$$H_5$/)$_4$-($CH_3$O)$_3$B-C$_2$$H_5$OH-$H_2O$계로부터 다공성의 SiO$_2$-B$_2$O$_3$ 막을 제조하였다. SiO$_2$-B$_2$O$_3$막의 특성을 BET, IR spectrophotometer, X-ray diffractometer, SEM 과 TEM을 사용하여 조사하였다. $700^{\circ}C$에서 얻어진 SiO$_2$-B$_2$O$_3$ 막의 평균 기공직경은 0.0048 $\mu\textrm{m}$이고, 표면적은 354.398 $m^2$/g이었으며, 입자의 크기는 7 nm인 무정형의 다공체이었다. SiO$_2$-B$_2$O$_3$ 막의 수소/질소 혼합 기체 분리 특성은 기체분리 압력을 달리하여 조사하였다. $25^{\circ}C$, ΔP 155.15cmHg에서 수소/질소 혼합 기체를 분리하여 본 결과 SiO$_2$-B$_2$O$_3$ 막의 수소에 대한 real separation factor($\alpha$)는 4.68이었다. 그리고 투과셀의 압력차(ΔP)값이 증가할수록 real separation factor($\alpha$), head separation factor($\beta$), tail separation factor((equation omitted))값이 증가하였다.

• 한국토양비료학회지
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• 제16권4호
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• pp.353-357
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• 1983

본(本) 실험(實驗)은 20개소(個所)의 초지토양(草地土壤)에서 토양(土壤)을 column으로 채취(採取)하여 탈질계(脫窒系)에 아세틸렌 가스를 주입(注入) 함으로서 모든 탈질최종생성물(脫窒最終生成物)을 $N_2O$로 유도(誘導)하는 방법(方法)으로 초지(草地)에서의 탈질(脫窒)을 측정(測定)하였던 바 그 결과(結果)는 다음과 같다. 1. 탈질계(脫窒系)에 $C_2H_2$를 주입(注入)하지 않았을 경우, 대부분의 시험구(試驗區)에서 $N_2O$의 발생(發生)은 탐지(探知)되지 않았으나, $C_2H_2$를 주입(注入)함으로서 모든 탈질생성물(脫窒生成物)은 $N_2O$로 탐지(探知)되었다. 2. 탈질계(脫窒系)를 물로 포화시켰을 때는 거의 모든 구(區)에서 탈질(脫窒)이 발생(發生)했으나, 자연상태(自然狀態)의 토양(土壤)column에서는 거의 탈질(脫窒)이 일어나지 않았다. 3. 요소(尿素)를 시비(施肥)한 후 13일(日)째로부터 16일(日)째 사이의 3일간(日間) 토양(土壤)column을 배양(培養)했을 경우 각(各) 구(區)의 평균(平均) 탈질양(脫窒量)은 4.2%였으며, 최대(最大)는 14.2%였다. 4. 탈질(脫窒)과 탈질계토양(脫窒系土壤)의 화학적성질(化學的性質)과의 사이에는 거의 상관(相關)이 없는 것으로 나타났으나 이는 토양(土壤)의 화학성(化學性)을 배양(培養)이 끝난 후에 행했기 때문인 것으로 판단(判斷)했다.

• 통합자연과학논문집
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• 제8권1호
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• pp.19-29
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• 2015

In view of the growing medicinal importance of chromene and its derivatives, the single crystal X-ray diffraction study was carried out for the potential active 4,6-dimethyl-9-phenyl-8,12-dioxa-4,6-diazatetracyclo [8.8.0.02,7.013,18]octadeca-2(7),13,15,17-tetraene-3,5,11-trione-2-ethoxyphenyl (2E)-but-2-enoate ($C_{18}H_{20}N_2O_5$). In the title compound are two molecules exist in the asymmetric unit. It crystallizes in the monoclinic space group $P2_1/c$ with unit cell dimension a=14.608(3) ${\AA}$, b=12.845(3) and c= 17.781(4) [alpha & gamma=$90^{\circ}$ beta=$91.233(5)^{\circ}$]. Both pyran and pyran ring of the chromene moiety adopts sofa conformation in the molecule A & B. The crystal structure is stabilized by intramolecular C-H...O hydrogen bond interaction.

• 한국대기환경학회지
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• 제19권5호
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• pp.529-540
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• 2003

A closed chamber system was used for measuring $N_2$0 fluxes from an agriculturally managed upland soil in Kunsan during the growing season from May to July 2002. It is known that soil is one dominant source of atmospheric $N_2$O, contributing to about 57% (9 Tg y $^{-1}$ ) of the total annual global emission. Hence, its increasing emissions and concentrations are largely associated with agricultural activities. In order to elucidate characteristics of soil nitrogen emissions from intensively managed agricultural soils and to understand the roles of soil parameters (soil moisture, soil pH, soil temperature, and soil nitrogen) in the gas emission, $N_2$O soil emissions were measured at every hour during the experimental period (21 days). Soil $N_2$O fluxes were calculated based on changes of $N_2$O concentrations measured inside a closed chamber at every hour. The analysis of $N_2$O was made by using a Gas Chromatography (equipped with Electron Capture Detector). Soil parameters at sampling plots were also analyzed. Monthly averaged $N_2$O fluxes during May, June, and July were 0.14, 0.05, and 0.13 mg-$N_2$O m$^{-2}$ h$^{-1}$ , respectively. Soil temperature and soil pH did not significantly vary over the experimental period; soil temperatures ranged from 12∼$25^{\circ}C$, and soil pH ranged 4.56∼4.75. However, soil moisture varied significantly from 32% to 56% in WFPS. Relationships between soil parameters and $N_2$O fluxes exhibited positive linear relationships. Strong positive correlation ($R^2$ = 0.57, P< 0.0001) was found between $N_2$O flux and sil moisture. It suggests that soil moisture has affected strongly soil $N_2$O emissions during the experimental periods, while other parameters have remained relatively at constant levels. $N_2$O flux from agricultural soils was significant and should be taken account for the national emission inventory.

• 한국미생물·생명공학회지
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• 제14권5호
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• pp.385-389
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• 1986

Rhodopseudomonas sp. KCTC 1437은 N $H_4^+$나 빛에 무관하게 수소를 발생할 수 있다. 이 사실로부터 이 균주는 nitrogenase뿐만 아니라 hydrogenase 에 의해서도 수소를 생성할 수 있다는 것을 확인했다. 이 두 효소의 수소생성 능력을 in vivo에서 측정할 수 있는 조건을 확립한 뒤 여러 가지 조건에 대해 발생한 수소양을 측정하였다. Hydrogenase 는 nitrogenase의 수소생성을 저해하는 $O_2$나 $N_2$, $C_2$ $H_2$ 등에 대해서도 그 활성의 감소가 없거나 작았으며, $H_2$에 의해서는 오히려 수소생성능이 증대되었단. 또 이 균주는 hydrogenase에 의해 수소를 밭아들여 $CO_2$를 광환원시킬 수도 있음도 알았다. 이상의 결과, hydrogenase가 혐기적이면서 빛이 있는 조건에서만 수소를 생성하는 nitrogenase보다 더 광범위하고 유리한 조건에서 수소를 생성할 수 있음을 확인하였다. 이러한 사실은 이 균주로 대량의 수소생산을 할 때 유리하게 이용될 수 있을 것이다.

• 한국전기전자재료학회논문지
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• 제37권1호
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• pp.101-105
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• 2024

4H-SiC power metal-oxide-semiconductor field effect transistors (MOSFETs) have been developed to achieve lower specific-on-resistance (R_on,sp), and the gate oxides have been thermally grown. The poor channel mobility resulting from the high interface trap density (D_it) at the SiO₂/4H-SiC interface significantly affects the higher switching loss of the power device. Therefore, the development of novel fabrication processes to enhance the quality of the SiO₂/4H-SiC interface is required. In this paper, NO post-oxidation annealing (POA) by using the conditions of N₂ diluted NO at a high temperature (1,300℃) is proposed to reduce the high interface trap density resulting from thermal oxidation. The NO POA is carried out in various NO ambient (0, 10, 50, and 100% NO mixed with 100, 90, 50, and 0% of high purity N₂ gas to achieve the optimized condition while maintaining a high temperature (1,300℃). To confirm the optimized condition of the NO POA, measuring capacitance-voltage (C-V) and current-voltage (I-V), and time-of-flight secondary-ion mass spectrometry (ToF-SIMS) are employed. It is confirmed that the POA condition of 50% NO at 1,300℃ facilitates the equilibrium state of both the oxidation and nitridation at the SiO₂/4H-SiC interface, thereby reducing the D_it.

• Bulletin of the Korean Chemical Society
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• 제18권2호
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• pp.213-217
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• 1997

Magnesium reduction of Mo(N-C6H3-2,6-i-Pr2)2Cl2(DME) in the presence of trimethylphosphine led to a mixture of Mo(N-C6H3-2,6-i-Pr2)(PMe3)2Cl3, 1, and Mo2(PMe3)4Cl4, 2. In solution 1 is slowly air-oxidized to Mo(N-2,6-i-Pr2-C6H3)(OPMe3)(PMe3)Cl3, 3. 1 is chemically inert to carbon nucleophiles (ZnMe2, ZnEt2, AlMe3, AlEt3, LiCp, NaCp, TlCp, NaCp*, MeMgBr, EtMgBr), oxygen nucleophiles (LiOEt, LiO-i-Pr, LiOPh, LiOSPh), and hydrides (LiBEt3H, LiBEt3D). Crystal data for 1: orthorhombic space group P212121, a=11.312(3) Å, b=11.908(3) Å, c=19.381(6) Å, Z=4, R(wR2)=0.0463 (0.1067). Crystal data for 2: monoclinic space group Cc, a=18.384(3) Å, b=9.181(2) Å, c=19.118(3) Å, b=124.98(1)°, Z=4, R(wR2)=0.0228 (0.0568). Crystal data for 3: orthorhombic space group P212121, a=11.464(1) Å, b=14.081(2) Å, c=16.614(3) Å, Z=4, R(wR2)=0.0394 (0.0923).

• Restorative Dentistry and Endodontics
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• 제2권1호
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• pp.11-14
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• 1976

The purpose of this study was to the observe effects of the various bleaching agents on blood clot. Absorbent papers(N9.5) were coated with O type blood and were dried in shadow for 72 hours. Bleaching agents used were 5% NaOCl 30% $H_2O_2$, saturated solutions of $NaBO_3$ $4H_2O$, $Ca(OCl)_2$ and $Na_2O_2$ at $20^{\circ}C$. After the specimens, blood cloted papers were dipped in 10CC of solution for 1 minute, 5 minutes, 30 minutes, 2 hours and 24 hours, specimens were washed with distilled water and dried. Hue Value/Chroma contrived by Munsell was measured in each specimen. The following results were obtained. 1. Superoxol changes 2.5YR 4.5/2 into N9.5 (white) after 24 hours. 2. All bleaching agents except superoxol change YR into Y.

• Journal of Microbiology and Biotechnology
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• 제14권4호
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• pp.751-758
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• 2004

The NCS(Non-Cariogenicity Sugar) from Bacillus sp. S-1013 was purified by cold acetone and methanol precipitation, and DEAE-cellulose ion-exchange and Sephadex G-100 column chromatographies, to yield an amorphous yellow syrup. The melting point and $[\alpha]_D^{20}$ were 155-$157^{\circ}C$ and +53, respectively. Instrumental analyses such as FT-IR, $^1H-NMR, and ^{13}C-NMR$ showed that the NCS contained an O-H group, C-H, C=O, $NH_2$, anomeric carbon, anomeric proton, N-acetylgalactose, fucose, and neuramic acid, thus, the NCS was determined to be a trisaccharide of Fuc($1\longrightarrow4$)GalNAc($2\longrightarrow6$) NeuAc.

• 한국결정학회지
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• 제17권2호
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• pp.41-45
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• 2006

[ $cis-[Co(13-aneN_4)(N_3)_2]Cl{\cdot}H_2O$ ] (1) (13-ane$N_4$ = 1,4,7,10-tetraazacyclotridecane) 착물(錯物)을 합성(合成)하고 구조(構造)를 규명(糾明)하였다. 이 착물(錯物)은 단사정계(單斜晶系), 공간군(空間群) Pbca, a = 7.8282(4) ${\AA}$, b = 14.3197(7) ${\AA}$, c = 29.9021(15) ${\AA}$, V= 3351.9(3) ${\AA}^3$, Z = 8로 결정화(決定化) 되었다. 착물(錯物) 1의 코발트(III)이온은 거대(巨大)고리 리간드의 4개(個)의 질소원자(窒素原子)와 시스 위치에 2개(個)의 azide 리간드가 결합(結合)한 고천(若干) 일그러진 팔면체(八面體) 구조(構造)를 갖는데, 착물(錯物)의 양이온, 염소(鹽素) 음이온 및 물분자(分子)를 통하여 1차원의 수소결합(水素結合)을 형성(形成)한다.