• Bulletin of the Korean Chemical Society
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• 제15권9호
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• pp.724-729
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• 1994

The effect of oxygen for the HF chemical laser performance has been theoretically investigated. Due to the inhibition mechanism of $O_2$ in $H_2$/$F_2$ chain reaction, the rate for the formation of HF is reduced by the addition of $O_2$. As the concentration of $O_2$ in the reaction mixture increases, the pulse power and temperature of the system becomes lower, while total output energy does not change significantly. But addition of $O_2$ makes the system easy to be controlled and the composition of $H_2$+$F_2$ can be high at constant total pressure. With this system, it is possible to obtain higher output energy than oxygen free environment.

• 청정기술
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• 제14권1호
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• pp.40-46
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• 2008

MCM 48, USY, beta 등과 같은 제올라이트를 세라믹종이에 실리카와 함께 도포하여 제습소자를 제조하였고, $H_2O$ 흡수 및 재생에 대한 평가를 고정층반응기에서 실시하였다. 제올라이트가 도포된 제습소자의 $H_2O$ 흡수력은 제올라이트가 도포되지 않은 제습소자보다 약 $1.5{\sim}2$배 가량 높은 것을 볼 수 있었다. 특히 콜로이드 실리카와 MCM 48을 도포한 제습소자는 약 42.1g $H_2O/g$ absorbent의 매우 우수한 제습 능력을 보여 주었다. 이러한 결과는 넓은 비표면적과 큰 기공부피를 가지고 있는 제올라이트에 의해 $H_2O$를 흡수할 수 있는 실리카 겔이 함침될 수 있는 공간이 증가하고 이에 따른 $H_2O$의 흡수량도 증가하는 것으로 판단된다. 또한 제올라이트가 도포된 제습소자는 $80^{\circ}C$의 재생 온도에서도 쉽게 $H_2O$가 탈착되고, 이 때 탈착된 $H_2O$의 양은 제습소자가 흡수한 $H_2O$의 양과 동일하였다. 반복순환실험을 통한 $H_2O$의 흡수력 감소는 발견되지 않았고 초기 흡수력이 유지되었다.

• Journal of Ginseng Research
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• 제29권3호
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• pp.145-151
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• 2005

식물조직배양기술을 이용하여 Ge를 함유한 인삼 root를 생산하고자, 0.5mg/L BAP와 3.0mg/L NAA조합의 식물생장 조절물질로 유도된 인삼 root를 이용하여 배양을 위한 최적 $GeO_2$농도, $GeO_2$ 첨가시기 및 배지의 pH를 조사하였다. 인삼 root의 생장에 가장 좋은 $GeO_2$ 농도는 10ppm, $GeO_2$ 첨가시기는 배양 초기(0주), pH는 5.5였고, 인삼 root내 Ge의 함량이 가장 높았을 때의 $GeO_2$농도는 100ppm이었다. $GeO_2$를 첨가하여 배양한 기간이 길수록 Ge함량이 증가하였으나 6주 이후부터 생장율이 둔화되어 $GeO_2$ 100ppm에서는 생장율이 아주 낮아 대조구의 1/2 정도였다. 배양 초기에 $GeO_2$를 첨가하여 8주간 배양한 인삼 root의 Ge 함량이 $29.4mg\%$인데 반해, 배양 2주째에 $GeO_2$를 첨가한 인삼 root의 경우는 Ge 함량이 $38.6mg\%$이므로, 배양 후 2주 후에 $GeO_2$를 첨가하는 것이 인삼 root의 Ge흡수에 더욱 효과적이었다. Ge흡수가 가장 잘 이루어지는 최적 pH는 5.5였으며 사포닌 함량은 $GeO_2$의 첨가농도가 증가할수록 감소하였다.

• 한국균학회지
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• 제24권3호통권78호
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• pp.223-227
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• 1996

팽이버섯 병 재배에 있어서 사과가공부산물의 첨가효과를 시험한 결과 배지재료별 화학적 특성은 사과가공부산물이 톱밥보다 산도(pH)가 낮았으며 T-N, $P_2O_5$, CaO, MgO는 비슷하였으나 T-C는 사과가중부산물이 다소 높았다 톱밥+미강배지에 사과가공부산물을 첨가하여 균사생장정도를 조사한 결과, 사과가공부산물 $5{\sim}20%$ 처리구는 톱밥+미강 20% 배지와 비슷하였으나 사과가공부산물 50%, 80% 처리구에는 pH가 5.1, 4.7로 강산성을 나타내어 균사생장이 불량하였다. 초발이 소요일수는 톱밥+미강 20% 처리구는 사과가공부산물 $5{\sim}20%$ 처리구의 $10{\sim}20$일과 비슷한 경향을 나타내었다. 배지종류별 수량을 보면 팽이버섯 재배에서 톱밥 사용량의 15%를 사과가공부산물로 대체 사용시 9%정도 증수되었다. 경제성 분석결과 톱밥사용량의 15%를 사과기공부산물로 대체 사용 시 소득지수가 29% 높게 나타났다.

• 한국자기공명학회논문지
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• 제26권1호
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• pp.10-16
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• 2022

The phase transition temperatures of CsCoCl₃·2H₂O crystals are investigated via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Three endothermic peaks at temperatures of 370 K (=T_C1), 390 K (=T_C2), and 416 K (=T_C3) were observed for phase transitions from CsCoCl₃·2H₂O to CsCoCl₃·1.5H₂O, to CsCoCl₃·H₂O, and then to CsCoCl₃·0.5H₂O, respectively. In addition, the spin-lattice relaxation time T_1ρ in the rotating frame and T₁ in the laboratory frame as well as changes in chemical shifts for ¹H and ¹³³Cs near T_C1 were found to be temperature dependent. Our analyses results indicated that the changes of chemical shifts, T_1ρ, and T₁ are associated with structural phase transitions near temperature T_C1. The changes of chemical shifts, T_1ρ, and T₁ near T_C1 were associated with structural phase transitions, owing to the changes in the symmetry of the structure formed of H₂O and Cs⁺ ions. Consequently, the structural symmetry in CsCoCl₃·2H₂O crystals based on temperature is discussed by the environments of their H and Cs nuclei.

• 천문학회지
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• 제49권6호
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• pp.261-288
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• 2016

We present the results of simultaneous monitoring observations of $H_2O$ $6_{1,6}-5_{2,3}$ (22GHz) and SiO J=1-0, 2-1, 3-2 maser lines (43, 86, 129GHz) toward five post-AGB (candidate) stars, using the 21-m single-dish telescopes of the Korean VLBI Network. Depending on the target objects, 7 - 11 epochs of data were obtained. We detected both $H_2O$ and SiO maser lines from four sources: OH16.1-0.3, OH38.10-0.13, OH65.5+1.3, and IRAS 19312+1950. We could not detect $H_2O$ maser emission toward OH13.1+5.1 between the late OH/IR and post-AGB stage. The detected $H_2O$ masers show typical double-peaked line profiles. The SiO masers from four sources, except IRAS 19312+1950, show the peaks around the stellar velocity as a single peak, whereas the SiO masers from IRAS 19312+1950 occur above the red peak of the $H_2O$ maser. We analyzed the properties of detected maser lines, and investigated their evolutionary state through comparison with the full widths at zero power. The distribution of observed target sources was also investigated in the IRAS two-color diagram in relation with the evolutionary stage of post-AGB stars. From our analyses, the evolutionary sequence of observed sources is suggested as OH65.5+1.3${\rightarrow}$OH13.1+5.1${\rightarrow}$OH16.1-0.3${\rightarrow}$OH38.10-0.13, except for IRAS 19312+1950. In addition, OH13.1+5.1 from which the $H_2O$ maser has not been detected is suggested to be on the gateway toward the post-AGB stage. With respect to the enigmatic object, IRAS 19312+1950, we could not clearly figure out its nature. To properly explain the unusual phenomena of SiO and $H_2O$ masers, it is essential to establish the relative locations and spatial distributions of two masers using VLBI technique. We also include the $1.2-160{\mu}m$ spectral energy distribution using photometric data from the following surveys: 2MASS, WISE, MSX, IRAS, and AKARI (IRC and FIS). In addition, from the IRAS LRS spectra, we found that the depth of silicate absorption features shows significant variations depending on the evolutionary sequence, associated with the termination of AGB phase mass-loss.

• KSBB Journal
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• 제10권3호
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• pp.292-297
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• 1995

Vero 세포를 이용한 뉴캐슬병 바이러스 생산에서 pH, 온도, 혈청농도, M.O.I. 등의 최적조건을 구하고 polycation, 항산화제, 그리고 DMSO 등의 첨가제가 바이러스 생산에 미치는 영향에 대한 연구를 수행하였다. 뉴캐슬병 바이러스의 최적 배양조건은 초기 p pH 7.2, 혈청농도 2 % FBS, 바이러스 접종량 0.1 M.O.I. 및 바이러스 증식온도 $34^{\circ}C$로 확인하였다. Polycation 인 DEAE-dextran, poly-L-Iysine과 항 산화제인 ascorbic acid는 각 $15\mu\textrm{g}/ml, 3\mu\textrm{g}/ml$그리고 0.1mM의 최적농도로 첨가했을 때 대조군에 비해 상당히 증대된 최대 바이러스 수율을 얻을 수 있었다.

• 전기학회논문지
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• 제60권4호
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• pp.801-804
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• 2011

Electrical properties and microstructure were investigated on the effects of $MnO_2$ and the lead-free $(Na_{0.44}K_{0.52}Li_{0.04})(Nb_{0.83}Sb_{0.07}Ta_{0.1})O_3$ ceramics with the addition of $MnO_2$ were fabricated by a conventional mixed oxide method. A gradual change in the crystal and microstructure was observed with the increase of $MnO_2$ addition. For the NKN-LST-xmol%$MnO_2$ sintered at $1100^{\circ}C$, bulk density increased with the addition of $MnO_2$ and showed maximum value at addition 1.0mol% of $MnO_2$. Curie temperature of the NKN-LST ceramics slightly decreased with adding $MnO_2$. The dielectric constant, piezoelectric constant ($d_{33}$) and electromechanical coupling factor ($k_p$) increased below 0.25mol% of $MnO_2$ addition, which might be due to the increase in density. The high piezoelectric properties = 145 pC/N, electromechanical coupling factor = 0.421 and dielectric constant = 2883 were obtained for the NKN-LST-0.25mol%$MnO_2$ sintered at $1100^{\circ}C$ for 4h.

• 한국재료학회지
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• 제19권3호
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• pp.163-168
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• 2009

$Eu^{3+}$-doped $Y_2O_3$ red phosphor was synthesized in a flux method using the chemicals $Y_2O_3,\;Eu_2O_3,\;H_3BO_3$ and $BaCl_2{\cdot}2H_2O$. The effect of a flux addition on the preparation of $Y_2O_3:Eu_{3+}$ red phosphor used as a cold cathode fluorescence lamp was investigated. $H_3BO_3$ and $BaCl_2{\cdot}2H_2O$ fluxes were used due to their different melting points. The crystallinity, thermal properties, morphology, and emission characteristics were measured using XRD, TG-DTA, SEM, and a photo-excited spectrometer. Under UV excitation of 254 nm, $Eu_2O_3$ 3.7 mol% doped $Y_2O_3$ exhibited a strong narrow-band red emission, peaking at 612 nm. From this result, the phosphor synthesized by firing $Y_2O_3$ with 3.7 mol% of $Eu_2O_3$, 0.25 mol% of $H_3BO_3$ and 0.5 mol% of $BaCl_2{\cdot}2H_2O$ fluxes at $1400^{\circ}C$ for 2 hours had a larger particle size of $4{\mu}m$ on average compared to the phosphor of the $H_3BO_3$ flux alone. In addition, a phosphor synthesized by the two fluxes together had a rounder corner shape, which led to the maximum emission intensity.

• 대한전기학회논문지
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• 제44권4호
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• pp.479-482
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• 1995

In this study, to improve sintering condition, anisotropic properties ( $k_{t}$/ $k_{p}$) of electromechanical coupling coefficient and piezoelectric constant $d_{h}$ and $g_{h}$, Mn $O_{2}$ impurity was added to the (P $b_{0.76}$C $a_{0.24}$)[( $Co_{1}$2/ $W_{1}$2/)$_{0.04}$ $Ti_{0.96}$] $O_{3}$ ceramics for application to hydrophone devices. Electromechanical coupling coefficients of the specimen with 1.5 [mol%] Mn $O_{2}$ sintered at 1150.deg. C were $k_{t}$=49% and $k_{p}$ = O, which exibited the highest value in piezoelectric anisotropic properties (kt/kp). Without relations with sintering temperature, the highest value of hydrostatic piezoelectric constant $d_{h}$ & $g_{h}$ were shown at the specimen with 1.5 [mol%] Mn $O_{2}$. Accordingly, the best addition amount of Mn $O_{2}$ was 1.5 [mol%] and proper sintering temperature was 1150.deg. C. Hydrostatic piezoelectric constant values of $d_{h}$=64.52[10$^{-12}$ C/N], $g_{h}$=35.92[10$^{-3}$ Vm/N] in the above condition were effectiely extended for hydrophone applications.pplications.ons.