• Journal of Pharmaceutical Investigation
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• 제30권1호
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• pp.33-37
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• 2000

One of the methods to increase the solubility of a drug is to use complexation with a cyclodextrin. Due to the hydrophobic nature of the interior cavity of the cyclodextrin, it has been known that undissociated lipophilic drugs can be included within the cyclodextrin by hydrophobic interaction. Recently, inclusion of hydrophilic or dissociated form of a drug has been investigated. In this study, the synergism of pH and complexation with $hydroxypropy-{\beta}-cyclodextrin\;(HP\;{\beta}\;CD)$ to increase the solubility of two oxicam derivatives was investigated. In addition, the effect of partition coefficient of dissociated and undissociated form of the drug on the extent of complexation with HP ${\beta}$ CD was studied. The solubility was measured by equilibrium solubility method. The solubility of tenoxicam and piroxicam increased exponentially with an increase in solution pH above the pKa of the drug in the presence and absence of HP ${\beta}$ CD. The solubility of the drugs increased linearly as a function of HP ${\beta}CD$ concentration at fixed pH. Although the stability constant of ionized species is less than that of the unionized species, the concentration of the ionized drug complex is greater than that of the unionized drug complex due to higher concentration of ionized species at pH 7.3.

• 한국전자파학회논문지
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• 제23권4호
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• pp.415-423
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• 2012

본 논문에서는 유전 알고리즘을 이용한 광대역 부배열 최적화 설계에 대해 기술하였다. 먼저 무한 주기 구조의 삼각 배열을 이용하여 광대역 복사 소자를 설계하였다. 너치 구조의 복사 소자로 정면 빔 조향 시 능동 반사 계수 -10 dB 이하를 만족하는 최대 및 최소 주파수 비가 약 2:1 정도로 광대역 특성을 가지고 있다. 이러한 광대역 배열 소자 1,100여개로 이루어진 안테나 구조의 부배열 최적화를 위해 유전 알고리즘을 이용하였다. 대조군인 규칙 부배열 안테나 구조와 비교해서 최적화(불규칙) 부배열 안테나 구조의 최대 부엽 준위가 4.5-5.5dB 정도 개선되었음을 확인하였다.

• Archives of Pharmacal Research
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• 제9권2호
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• pp.111-114
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• 1986

Bretylium tosylate is a quaternary ammonium compound used for the treatment of ventricular fibrilation in humans. It is advantageous to other cationic compound in the study of biliary excretion in that negligible amount is bound to plasma protein and metabolite is not likely is to be formed. Some researchers reported that the formation of ion-pair complex caused to increase the lipothilicity of cationic compound. The partition of bretylium between water and organic phase was increased with the addition of sodium taurodeoxycholate. Also sensitive gas chromatographical assay procedure using flame ionization detector was studied. This procedure can detect as low as 0.1 mg/ml using 0.1 ml biological sample, but contamination by previous injection is the major problem of this method.

• Journal of Pharmaceutical Investigation
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• 제16권2호
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• pp.55-67
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• 1986

Inclusion complexation of tiaprofenic acid (TPA) with cyclodextrins $({\alpha}-,\;{\beta}-,\;{\gamma}-CyDs)$ in aqueous solution and in solid phase was investigated by solubility method, measurement of partition coefficient, ultra-violet, circular dichroism, infrared spectroscopies, powder X-ray diffractometry and differential scanning calorimetry. Investigations were made to prepare inclusion complexes of TPA with ${\beta}-CyD$ in solid powdered form by coprecipitation, freeze-drying, spray-drying and co-pulverization methods. The coprecipitation, freeze-drying and spray-drying methods were successful in obtaining inclusion complexes. The results showed that the latter two methods might be originally superior to the former in obtaining powdered inclusion completes. Especially, it was shown by powder X-ray diffractometry that spray-dried ${\beta}-CyD$ alone, TPA-spray-dried ${\beta}-CyD$ physical mixture, and spray-dried $TPA-{\beta}-CyD$ complex were amorphous. The dissolution behaviours of $TPA-{\beta}-CyD$ systems prepared by above four methods were compared with those of TPA alone and $TPA-{\beta}-CyD$ physical mixture, and the rates of dissolution of TPA in pH 1.2 buffer were greatly enhanced by inclusion complexation and copulverization.

• 한국잠사곤충학회지
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• 제24권2호
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• pp.81-84
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• 1983

견사에 대한 산성염료인 Orange II의 평형수착을 pH 2.2 HCl염욕중에서 온도 50$^{\circ}$, 70$^{\circ}$ 및 9$0^{\circ}C$로 변화시켜, 또한 온도 $50^{\circ}C$에서 pH를 1.5, 2.2 및 4.0으로 조절하여 수착식을 검토하였다. pH 1.5 및 2.2에서의 수착식은 이원 model 즉 Langmuir형과 Nernst형의 합으로 표시됨을 알았다. Langmuir 수착평행상수 $K_{L}$ 은 온도의 상승과 pH의 증가에 따라 감소하였고, Nernst분배계수 $K_{P}$ 도 비슷한 경향을 보였다. 수착 반응은 발열반응임을 알 수 있었고 표준 entropy는 정의 값임을 알았다.

• 한국물환경학회지
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• 제20권3호
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• pp.296-300
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• 2004

The rejection properties of 6 aromatic pesticides were evaluated by a continuous flow system equipped with a hollow fiber NF membrane. Different from the separation experiment of batch cell, the rejection and the removal could be calculated exactly because the concentration of feed, permeate and retentate was separately obtained. The lowest and the highest rejection were found in carbaryl(54.8%) and methoxychlor(99.2%), respectively, and the removals were always shown higher than rejections. This may be caused by some reasons such as the solute adsorption on the membrane, the variation of feed concentration. Although molecular weight, molecular width regarded as solute characteristics and log P(n-octanol/water partition coefficient) as hydrophobicity could be applied to explain the rejection property, these factors should be considered together for better analysis. According to the higher relationship between log B(solute permeability) and molecular weight, it was revealed that the solute separation with this membrane was influenced more by molecular weight.

• 한국염색가공학회지
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• 제2권3호
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• pp.36-42
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• 1990

The effect of urea and its derivatives, which are known as structure breakers of water, in the dyeing of silk with acid dyes was investigated. Without ureas the maximum dye uptake was observed at $60^{\circ}C$ when dyed with Milling Cyanine 5R, but in the presence of ureas the maximum dye uptake was decreased and its temperature also shifted to lower regin in the order of urea >N-methyl urea > N,N-dimethyl urea>tetramethyl urea. These tendencies were more marked in the dyeing of silk fiber with Orange II, a typical levelling type acid dye. These can be interpreted as the decrease in the hydropholic interaction between fiber molecules which results in the broadening of the inter micelie spacing. The increased partition coefficient of dye molecules in the bath by the action of ureas also contributes to dyeing results, and it can be seen from the spectral characteristics of dyes in aqueous urea solution.

• Bulletin of the Korean Chemical Society
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• 제5권3호
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• pp.104-108
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• 1984

The self-diffusion experiment of THO was performed across a series of copolymer hydrogel membranes at different temperatures. Copolymer hydrogel membranes were prepared by copolymerizing 2-hydroxyethyl methacrylate (HEMA) and 2-aminoethyl methacrylate (AEMA) in the presence of the solvent and the crosslinker, ethylene glycol dimethacrylate (EGDMA). By changing the crosslinker content and the ratio of HEMA and AEMA monomer, two series of copolymer hydrogel membranes were synthesized. The tagging material was THO and efflux of THO was counted on a Liquid Sc-intillation Counter. The experimental data show that the permeability decreases as the amount of EGDMA and the mole fraction of HEMA increase, and the permeability is proportional to the temperature. The partition coefficient shows a parallel trend with permeability. Using the relationship between viscosity and diffusivity, the viscosity of water within the membrane was obtained. According to the result, the viscosity of watler within the membrane has the same value with those of supercooling water. And we obtained the activation energy of THO for transport in the membrane by using Arrhenius plotting.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권4호
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• pp.33-48
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• 2017

An optimum disposal plan of disused sealed radioactive sources (DSRSs) should be established to ensure long-term disposal safety at the low- and intermediate-level radioactive waste (LILW) disposal facility in Gyeongju. In this study, an optimum disposal system was suggested and preliminary post-closure safety assessment was performed. The DSRSs disposal system was composed of a rock cavern and near surface disposal facilities at the Gyeongju LILW disposal facility. The assessment was conducted using GoldSim program, and probabilistic assessment and sensitivity analysis were implemented to evaluate the uncertainties in the input parameters of natural barriers. Deterministic and probabilistic calculations indicated that the maximum dose was below the regulatory limits ($0.1mSvyr^{-1}$ for the normal scenario, $1mSvyr^{-1}$ for the well scenario). It was concluded that the DSRSs disposal system would maintain environmental safety over a long-time. Moreover, the partition coefficient of Np in host rock, Darcy velocity in host rock, and density of the host rock were the most sensitive parameters in predicting exposure dose in the safety assessment.

• 공업화학
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• 제32권5호
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• pp.581-588
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• 2021

In this study, soil slurry bioreactors were used to treat soils containing 16 polycyclic aromatic hydrocarbons (PAHs) for 35 days. Five different soil samples were taken from manufactured gas plant (MGP) and coal tar disposal sites. Soil properties, such as carbon content and particle distribution, were measured. These properties were significantly correlated with percent biodegradation and degradation rate. The cumulative amount of PAH degraded (P), degradation rate (K_m), and lag phase (𝜆) constants of PAHs in different MGP soils for 16 PAHs were successfully obtained from nonlinear regression analysis using the Gompertz equation, but only those of naphthalene, anthracene, acenaphthene, fluoranthene, chrysene, benzo[k]fluoranthene, benzo(a)pyrene, and benzo(g,h,i)perylene are presented in this study. A comparison between total non-carcinogenic and carcinogenic PAHs indicated higher maximum amounts of PAH degraded in the former than that in the latter owing to lower partition coefficients and higher water solubilities (S). The degradation rates of total non-carcinogenic compounds for all soils were more than four times higher than those of total carcinogenic compounds. Carcinogenic PAHs have the highest partitioning coefficients (K_oc), resulting in lower bioavailability as the molecular weight (MW) increases. Good linear relationships of K_m, 𝜆, and P with the octanol-water partitioning coefficient (K_ow), MW, and S were used to estimate PAH remaining, lag time, and biodegradation rate for other PAHs.