• 한국재료학회지
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• 제24권3호
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• pp.129-134
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• 2014

Pure $MgH_2$ was milled under a hydrogen atmosphere (reactive mechanical grinding, RMG). The hydrogen storage properties of the prepared samples were studied at a relatively low temperature of 423 K and were compared with those of pure Mg. The hydriding rate of the Mg was extremely low (0.0008 wt% H/min at n = 4), and the $MgH_2$ after RMG had higher hydriding rates than that of Mg at 423 K under 12 bar $H_2$. The initial hydriding rate of $MgH_2$ after RMG at 423 K under 12 bar $H_2$ was the highest (0.08 wt% H/min) at n = 2. At n = 2, the $MgH_2$ after RMG absorbed 0.39 wt% H for 5 min, and 1.21 wt% H for 60 min at 423K under 12 bar $H_2$. At 573 K under 12 bar $H_2$, the $MgH_2$ after RMG absorbed 4.86 wt% H for 5 min, and 5.52 wt% H for 60 min at n = 2. At 573 K and 423 K under 1.0 bar $H_2$, the $MgH_2$ after RMG and the Mg did not release hydrogen. The decrease in particle size and creation of defects by reactive mechanical grinding are believed to have led to the increase in the hydriding rate of the $MgH_2$ after RMG at a relatively low temperature of 423 K.

• The Korean Journal of Ecology
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• 제3권1_2호
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• pp.11-16
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• 1980

무시비구, 질소시비구(6.67gN/$m^2$) 및 과질소비구(13.34gN/$m^2$)의 질소구배처리에 따른 대두개체군의 생육과정별 제 생장해석적특징 및 일차생산성을 비교검토하였다. 질소시비구 및 과질소시비구에서는 대조구에 비해 8~10배의 순질소흡수율과 비교적 높은 생산성 및 최대 LAI의 도달이 2주정도 빨리 나타났고 SLA의 증가를 보였으나, 근립의 형성은 1/3~1/4의 감소를 보였다. 그러나, H, F/C, T/R, RGR, NAR, 및 CGR 등 생장해석적특징에는 큰 유의차가 없었다.

• 멤브레인
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• 제8권4호
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• pp.228-234
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• 1998

다양한 수질 오염원 중 페놀과 같은 유기화합물은 배출조건이 비정상적인 경우 기존의 처리방법으로 제거하거나 파괴하기 어렵다. 수용액으로부터 페놀을 분리하기 위한 최근의 연구들은 활성탄에 의한 흡착, 용매 추출 등에 의해 수행되어져 왔으며, 물-기름 유화에 기초를 둔 액막법이 기존의 기술들을 대체하기 위한 방법으로 시험되어져 왔다. 본 연구에서는 tri-n-butyl phosphate(TBP)와 액상 고분자를 지지액막의 액막용액으로 선정하여 수용액상의 페놀을 분리하였다. 공급측 페놀 농도를 변화시키고 다양한 액막용액을 사용하여 이들이 페놀분리에 미치는 효과를 연구하였다. TBP를 운반체로 사용한 경우의 실험결과들은 용매추출에서 주로 사용되고 있는 methyl isobutyl ketone(MIBK)보다 높은 물질전달속도를 보여주었으며, 선택한 액상고분자 중 polypropylene glycol 4000(PPG-4000), polybutylene glycol 500(PBG 500)의 경우 MIBK와 유사하거나 조금 높은 값을 나타내었다.

• The Korean Journal of Ecology
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• 제5권4호
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• pp.204-210
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• 1982

Comparative study of the biomass productioin and the cyclings of nitrogen, phosphorus and potassium was carried out on the east and the northwest facing slope in the montane grassland of Mt. Soback. The maximum productin during the growing season in the east and the northwest slope were 1, 150g/m2.yr, and 755g/m2.yr. in the August, respectively. The positive correlation was appearent between biomass production and A-layer depth of the soil and the correlation coefficient (r=.964) was very significant at 1% level. In the above ground materials, the nutrients contents were high at the early of the growing season but decreased gradually. In roots, however, there are no significant trend throughout the growing season. Total amounts of minerals uptaken by plants during the growing season in the east and the northwest site were 18.20 and 10.66g/m2.yr for N, 0.06 and 0.03g/m2.yr for P, 0.23 and 0.11g/m2.yr for K, respectively. the minerals returned to the soil by litter decomposition and roots decay in the east and the northwest site were 16.19 and 9.62g/m2.yr for N, 0.046 and 0.021g/m2.yr for P, 0.211 and 0.099g/m2.yr for K, respectively. The turnover the rate (absorbed/returned) of the nutrients in the east and the northwest site were 1.13 and 1.14 for N, 1.30 and 1.43 for P, 1.09 and 1.11 for K, and the absorption rates of minerals were 0.39 and 0.29% for N, 3.16 and 1.88% for P, 0.91 and 0.57% for K, respectively.

• 한국전자파학회논문지
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• 제10권7호
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• pp.1095-1103
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• 1999

현재 helix와 monopole로 구성되는 안테나를 갖는 수납형 전화기(retractble phone)가 셀룰라 이동통신에서 가장 널리 사용되고 있다. 그러나 안테나의 monopole의 길이가 약 $\lambda$/4이므로, 강한 복사 전기장이 전화기를 사용하는 인체 두부의 외이 주변에 주로 분포한다. 이러한 전기장 분포는 두부 내에 매우 높은 국부 SAR(specific abs$\alpha$ption rate)을 야기한다. 본 논문은 이동통신단말기의 안테나 배치가 반대인 전화기 형상에 대한 두부 내 전자파 흡수율을 기존의 단말기 형상의 것과 비교, 고찰한다. 이것은 단말기 옴체의 상부가 아닌 바닥 에 안테나를 배치하는 것이다. 인체와 단말기 모델을 포함하는 계산 공간의 시간-평균 전자기장 분포를 얻기 위해 시간영역 유한차분( FDTD) 기법을 사용하였다. 그리고 SAR 분포와 국부 SAR 값이 시간-명균 전기장 분포로부터 계산되었다. 실제 상황을 고려하기 위해 해부학적 인체 두부 모델과 근사된 사용자 손이 고려되었 다. 분석된 데이터는 안테나의 이 같은 배치가 인체 두부 내에 국부 SAR을 상당히 감소시킴을 보인다.

• Journal of Pharmaceutical Investigation
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• 제34권6호
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• pp.443-452
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• 2004

Habit is the description of the outer appearance of a crystal. If the environment of a growing crystal affects its external shape without changing its internal structure, a different habit results. Crystal habit and the internal structure of a drug can affect bulk and physicochemical properties, which range from flowability to chemical stability. A polymorph is a solid crystalline phase of a given compound resulting from the possibility of at least two different arrangements of the molecules of that compound in the solid state. Chemical stability and solubility changes due to polymorphism can have an impact on a drug's bioavailability and its development program. During crystallization from a solution, crystals separating may consist of a pure component or be a molecular compound. Solvates are molecular complexes that have incorporated the crystallizing solvent molecule in their lattice. When the solvent incorporated in the solvate is water, it is called a hydrate. To distinguish solvates from polymorphs, which are not molecular compounds, the term pseudopolymorph is used. Identification of possible hydrate compounds is important since their aqueous solubilities can be significantly less than their anhydrous forms. Conversion of an anhydrous compound to a hydrate within the dosage form may reduce the dissolution rate and extent of drug absorption. An amorphous solid may be treated as a supercooled liquid in which the arrangement of molecules is random. Amorphous solids lack the three-dimensional long-range order found in crystalline solids. Since amorphous forms are usually of higher thermodynamic energy than corresponding crystalline forms, solubilities as well as dissolution rates are generally greater. A study on crystal form includes characterization of (l)crystal habit, (2)polymorphism, (3)pseudopolymorphism, (4)amorphous solid.

• Journal of Pharmaceutical Investigation
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• 제16권2호
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• pp.43-54
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• 1986

To increase the bioavailability of clonixin, clonixin argininate was prepared and compared with clonixin by determining solubility, pKa, lipid-water partition coefficient, dissolution rate and in vivo tests. The results are summerized as followings; 1) The solubility of clonixin argininate was increased by 20 times in water, about 1.2 times in pH 1.2 and pH 8.0 buffer solution, and about 1.8 times in pH 6.8 buffer solution compared with that of clonixin. 2) pKa values of clonixin, clonixin lysinate and clonixin argininate were 6.32, 7.20 and 7.45, respectively. 3) The lipid-water partition coefficient of clonixin argininate was increased more than that of the clonixin in n-hexane, carbon tetrachloride, chloroform, methylene chloride, and n-butanol, but the partition coefficient of clonixin was increased more than that of clonixin argininate in benzene/pH 1.2 buffer solution, ether/pH 8.0 buffer solution, and 3-methylbutyl acetate/pH 1.2, pH 8.0 buffer solution. 4) The time required to dissolve 60% $(T_{60%},\;min.)$ of clonixin argininate was about 1.5 min. in water and pH 1.2 buffer solution, and about 5 min. in pH 6.8 buffer solution. $T_{60%}$ of clonixin lysinate was about 1.5 min. in water, about 1.8 min. in pH 6.8 buffer solution, and about 8 min. in pH 1.2 buffer solution. But $T_{60%}$ of clonixin was about 96 min. in pH 6.8 buffer solution, over 2 hours in water and pH 1.2 buffer solution. 5) Anti-inflammatory effect of clonixin argininate was increased more than that of clonixin over 6 hours, and that of clonixin lysinate was followed by lapse of time. 6) Analgesic effect of clonixin argininate was increased by 1.5 times more than that of clonixin and the effect of clonixin argininate was nearly identical with that of clonixin lysinate. 7) The absorption rates (Ka) of clonixin, clonixin lysinate and clonixin argininate were $0.169\;hr^{-1},\;0.652\;hr^{-1}$ and $0.723\;hr^{-1}$ in situ, respectively.

• Journal of Biosystems Engineering
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• 제27권1호
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• pp.39-44
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• 2002

In order to obtain the information of bio-environment control, the thermal characteristics of soil in the greenhouse heated by the heat pump and latent heat storage system were experimentally analyzed. The experimental systems were composed of the greenhouse with a heat pump and a latent heat storage system (system I), the greenhouse with a heat pump (system II), the greenhouse with a latent heat storage system (system III), and the greenhouse without auxiliary heating system (system IV). The thermal characteristics experimentally analyzed in each system were temperature of soil layers, soil heat storage and release, soil heat capacity and soil heat storage ratio. The results could be summarized as follows. 1. Time to reach the highest temperature at 20cm deep in soil layers of the crop routs in case of system I was shown to be delayed by 6 hours in comparison to the time of the highest temperature at the soil surface. 2. In the clear winter days, the stored heat capacity values fur the system I and the system II were shown to be 22.3% and 11.0% higher than the released heat capacity respectively, and the stored heat capacity values for the system III and the system IV were shown to be 6.2% and 29.6% lower than the released heat capacity respectively This confirms that the system I provided the best heat storage effect. j. The heat quantity values stored or released were shown to be highest at 5 cm depth of soil layers. And it was reduced with increasing of depth of soil layers until 20 cm and was not changed under the soil layer of 20 cm depth. 4. The heat absorption rates of soil, the ratio between supplied and stored heat energy, fur both the system I and system II were lower than 23%.

• 펄프종이기술
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• 제41권3호
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• pp.49-59
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• 2009

The bast fibers of paper mulberry were dyed by using sappan wood, gardenia, and gallnut extracted under various extraction conditions. The surface absorption rates, color, and sunlight fastness of the dyed fibers were compared to those of the dyed cotton and silk. The K/S values of silk showed the highest values, followed by gallnut, gardenia, and sappan wood. The optimum extraction conditions of the dye materials were 20 g/L (input amount of dye materials per liter), $90^{\circ}C$ (extraction temperature), and 30 minutes (extraction time). The values of saturation were observed to increase with the increase of the amount of dye materials, extraction time, and extration temperature. However, no effect were found on the values of hue and lightness. In all samples, the developed colors dyed by sappan wood and gardenia were the series of YR, and Y, respectively. The colors of dyed cotton and bast fibers of paper mulberry by gallnut were the series of Y and the dyed silk showed the series of YR. The values of saturation of the bast fibers of paper mulberry by sappan wood and gardenia showed the highest values of saturation, followed by cotton, and silk. In the case of gallnut, cotton showed the highest values of saturation, followed by the bast fibers of paper mulberry, and silk. The sunlight fastness were not improved in all dyeing conditions.

• 한국방사선학회논문지
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• 제8권4호
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• pp.155-161
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• 2014

유방촬영의 경우 대부분 양쪽 유방에 대해 연속촬영이 시행되고 있으며, 검사 시 규정하고 있는 3 mGy의 평균유선선량 보다 낮다 하더라도 추가 검사 및 연속촬영으로 인해 실제는 더 많은 선량을 받게 된다. 또한 검사 유방 외에 주변장기선량에 대해 인지하기 어렵다. 이에 본 연구는 유방영상시스템에서 수학적 모의피폭체를 이용하여 필터의 두께 변화(25, 30, $50{\mu}m$)에 따른 주변장기 선량분포와 검사측 유방을 기준으로 한 상대적 흡수선량률을 알아보았다. 그 결과 검사 반대 유방의 선량이 검사 유방을 기준으로 79.26~86.31%정도로 많은 영향이 미치는 것으로 나타났으며, Mo/Mo, W/Rh 조합에서 실제 사용되고 있는 필터 두께 $30{\mu}m$, $50{\mu}m$ 보다 얇은 $25{\mu}m$를 사용했을 때 검사 반대 유방과 주변장기의 상대적 흡수선량률이 낮게 나타났다.