검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 38

        21.
        2007.09 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 고려엉겅퀴 추출물의 항산화 효과, 사람섬유아세포에 자외선에 의해 유도된 MMP-1 발현에 대한 영향 및 피부탄력 개선효과에 대하여 연구하였다. 고려엉겅퀴 추출물의 DPPH radical과 superoxide anion radical 소거효과는 처리 농도가 증가함에 따라 농도 의존적으로 소거효과를 나타냈으며, 각각 1 mg/mL에서 87.47 %와 61.71 %로 DPPH radical과 superoxide anion radical을 소거하여 우수한 항산화 효과를 나타내었다. 고려엉겅퀴 추출물의 지질과산화 억제효과는 100 g/mL 농도에서 95.54 %의 지질과산화 저해효과를 나타내었다. 또한, 자외선 조사에 의해 사람 섬유아세포에서 증가되는 MMP-1의 단백질 발현은 고려엉겅퀴 추출물을 100 g/mL 농도로 처리하였을 때 54.69 % 감소하였다. 피부의 탄력 개선 효과를 알아보기 위해 고려엉겅퀴 추출물을 500 g/mL 함유한 O/W 에멀젼을 이용한 임상실험에서 피부의 탄력 개선 효과를 확인하였다. 본 연구를 통하여 고려엉겅퀴 추출물은 항산화 효과와 자외선으로부터 생성되는 MMP-1의 발현을 저해하고 피부의 탄력을 개선함으로써 항노화 소재로서의 응용가능성을 확인하였다.
        22.
        2007.03 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 돌나물추출물이 각질형성세포에서 hyaluronan synthase (HAS) mRNA 발현과 hyaluronan (HA) 생성에 미치는 영향을 알아 보았다. 또한 돌나물추출물이 가지는 인체 피부에서의 보습력 증진 효과를 평가하였다. 돌나물추출물 처리에 따른 각질형성세포에서의 HAS-1, -2, -3 mRNA 발현 변화는 semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR)을 통해 살펴보았고, HA의 생성량 변화는 enzyme-linked immunosorbent assay (ELISA)를 수행하여 확인하였다. 인체 피부에서의 수분함량 및 피부 수분 손실량에 미치는 영향은 Corneometer와 Tewameter를 이용하여 측정하였다. 그 결과, 돌나물추출물은 사람 각질형성세포의 HAS-2, -3 mRNA의 발현을 증가시켰고, HA의 생성량을 농도의존적으로 증가시킴을 확인하였다. 사람 피부에서는 수분 함량을 유지하는 효과가 우수하였으며, 표피 수분 손실량 또한 감소시켜 피부 보습제로서 매우 우수한 효과를 보였다. 이상의 결과를 통해 돌나물은 피부에서 HA 생산을 촉진시키며, 피부 보습력을 증진시키는 화장품 소재로 이용될 수 있을 것으로 사료된다.
        28.
        2005.01 KCI 등재 서비스 종료(열람 제한)
        Adsorption characteristics of toluene vapor, which is one of important source of volatile organic compounds (VOCs), by activated carbon were investigated using a fixed bed adsorption column. The operating parameters such as breakthrough curve, adsorption capacity, mass transfer zone (MTZ), and length of unused bed (LUB) were studied. The experimental results showed that the breakthrough time decreased with increasing inlet toluene concentration and gas flow rate. MTZ and LUB increased with the increase of inlet concentration, gas flow rate, and particle size of activated carbon. The adsorption capacity increased with the increase of inlet toluene concentration, while it decreased with increasing particle size. However, it was kept at constant value regardless of the increase of gas flow rate. Adsorption isotherm of toluene vapor could be represented by the Freundlich adsorption equation fairly well. From the adsorption experiments using some VOC gases such as toluene, xylene, butyl acetate. butanol and acetone, it was also found that the adsorption capacity was higher in the case of gas with higher boiling point and lower vapor pressure.
        30.
        2003.11 KCI 등재 서비스 종료(열람 제한)
        본 연구는 자기평가체형이 사회적 체형불안과 신체적 자기개념에 어떠한 영향을 미치는지 분석하는데 그 목적이 있다. 구체적인 방법으로는 남·여 중학생 332명(남: 173명, 여:159명)을 대상으로 자신의 체형을 너무마름, 약간마름, 보통, 약간살찜, 너무살찜으로 평가한 집단간 사회적 체형불만(Social Physique Anxiety Scale, SPAS)과의 관계를 이원 단일변량분산분석(two way ANOVA)을 통해 알아보았고, 신체적 자기개념(Physical Self-Description Questionnaire, PSDQ)의 하위요인간의 관계를 알아보기 위해 이원 다변량분산분석(two way MANOVA)을 통해 알아보았다. 그리고 사회적 체형불안과 신체적 자기개념의 하위요인간의 상관관계를 알아보았다. 비교결과, 사회적 체형불안은 성별에 있어서는 유의한 차이가 나타나지 않았으나, 자기체형 인식에 따라서는 보통이라고 평가한 집단이 가장 낮고, 너무 살찜이라고 평가한 집단이 가장 높게 나타났다. 신체적 자기개념에서는 남학생이 신체활동, 건강, 지구력, 스포츠유능감 요인에서 여학생보다 높게 나타났고, 자기체형 인식에 따른 집단간에는 보통과 약간 마름의로 평가한 집단에서 체지방, 외모, 건강, 자기존중, 유연성, 지구력, 신체전반의 7개 요인에서 가장 높은 점수를 나타내었다. 마지막으로, 남학생과 여학생 모두 체지방과 자기존중에서 사회적 체형불안과 높은 상관관계가 발견되었고, 여학생에게서 더 높은 상관관계가 나타났다. 이외에도 여학생은 스포츠유능감요인과 지구력요인에서도 사회적 체형불안과 유의한 관계가 있다는 것이 발견되었다. 결론적으로, 자기체형을 어떻게 인식하고 있느냐에 따라 신체적 자기개념의 각 하위 구성요인에 차이가 난다는 것을 보여주고 있고, 사회적 체형불안과 신체적 자기개념과의 상관관계를 설명하는데 있어서 남학생보다는 여학생에게서 더 높은 관계를 나타내고 있다는 것을 시사하고 있다.
        31.
        2003.10 KCI 등재 서비스 종료(열람 제한)
        The adsorption behaviors of strontium and cesium ions on fly ash, natural zeolites, and zeolites synthesized from fly ash were investigated. The zeolites synthesized from fly ash had greater adsorption capabilities for strontium and cesium ions than the original fly ash and natural zeolites. The maximum adsorption capacity of synthetic zeolite for strontium and cesium ions was 100 and 154 mg/g, respectively. It was found that the Freundlich isotherm model could fit the adsorption isotherm. The distribution coefficients (Kd) for strontium and cesium ions were also calculated from the adsorption isotherm data. The distribution coefficients decreased with increasing equilibrium concentration of strontium and cesium ions in solution. By studying the removal of cesium and strontium ions in the presence of calcium, magnesium, sodium, potassium, sulfate, nitrate, nitrite, and EDTA (in the range of 0.01 - 5 mM) it was found that these coexistence ions competed for the same adsorption sites with strontium and cesium ions.
        32.
        2003.10 KCI 등재 서비스 종료(열람 제한)
        Adsorption on goethite of individual component from a solution containing phosphate, sulfate, or copper ion was investigated. Competitive adsorption in the binary and ternary solution systems composed of phosphate, sulfate, and copper ions was also investigated. In competitive adsorption systems with phosphate and sulfate ions, the presence of phosphate ion reduced the adsorption of sulfate ion largely. On the other hand, the presence of sulfate ion caused only a small decrease in phosphate adsorption. This result suggests that phosphate ion is a stronger competitor for adsorption on goethite than sulfate ion, which is consistent with the higher affinity of phosphate for the surface compared to sulfate ion. Compared to the results from single-sorbate systems, adsorption of copper ion in the binary system of sulfate ion and copper ion was found to be enhanced in the presence of sulfate ion. Addition of sulfate ion to the binary system of copper ion and phosphate ion resulted in a small enhancement in copper sorption. This result implies that the presence of sulfate ion promotes adsorption of the ternary complex FeOHCuSO4. The adsorption isotherms could be well described by the Langmuir adsorption equation.
        33.
        2002.03 KCI 등재 서비스 종료(열람 제한)
        This study was conducted to know the removal characteristics of ammonia nitrogen by commercially available cation exchange resins. Eight acidic cation exchange resins were investigated in batch reactors. Among them, the most effective resin for ammonia removal in solution was PK228, which was a strong acidic resin of Na+ type. PK228 was compared with activated carbon and natural zeolite. The effects of cation exchange capacity, ammonia concentration, resin amount, temperature and pH on ammonia removal by PK228 were investigated in batch reactor, and the effect of effluent velocity in continuous column reactor. Strong acidic resins of porous type were more effective than week acidic resins or gel type resins for ammonia removal in solution. PK228 was more effective than activated carbon and natural zeolite for ammonia removal in batch reactor. With increasing initial ammonia concentration, the amount of ammonia removed by PK228 increased, but the proportion of removed ammonia to initial ammonia concentration decreased. The effect or temperature on ammonia removal by PK228 was very slight. The ammonia removal to acidic solution was more effective than that at basic solution. With decreasing effluent velocity of solution through column, breakthrough point extended, and ammonia removal capacity increased.
        34.
        2000.08 KCI 등재 서비스 종료(열람 제한)
        Nitrate-selective ion exchange resin which have bulky tertiary amine as functional group have been synthesized by the reaction of chloromethylated polystyrene-divinylbenzene copolymer and the corresponding tertiary amine [NR3=NEt3 1, N(C2H4OH)3 2] in ethanol, while commercial resin has NMe3 as functional group. The fundamental properties such as bulk density, water content, appearance index, exchange capacity, effective size, uniformity coefficient of synthesized anion exchange resin (1) have been measured. The ion exchange resin (1) and (2) exhibited the better selectivity for nitrate than sulfate in both batch and continuous column experiments.
        35.
        2000.06 KCI 등재 서비스 종료(열람 제한)
        A kinetic study for nitrate removal by anion exchange resin was performed using continuous column reactors. Kinetic approach from the packed bed showed the reaction rate constant k1 was 0.07∼0.17 ℓ/㎎·hr and maximum exchange quantity q0 was 27.75∼31.81 ㎎/g. The results from the continuous column well agreed with that from the batch reactor. An economic analysis of the water treatment plant by anion exchange resin with a regenerating system was performed to design plant and process. Based on the treatment of 20 ㎎/ℓ nitrate-contained wastewater of 10,000 gallons per day to 2 ㎎/ℓ , total capital cost and total annual cost are estimated to be 836 million wons and 211 million wons, respectively.
        37.
        2000.04 KCI 등재 서비스 종료(열람 제한)
        A kinetic study for anion exchange was performed for commercially available Cl- type anion exchange resin in use to remove nitrate in water. The obtained results from the batch reactor were applied to the Langmuir and Freundlich models. The constants for Langmuir model were qmax=29.82 and b=0.202, and for Freundlich model were K=5.509 and n=1.772. Langmuir model showed better fit than Frendlich model for the experimental results. Ion exchange reaction rate was also calculated and the approximate first-order reaction, rate constant k1 was 0.16 L/㎎·hr. Effective diffusion coefficient was obtained in the range from 9.67×10 exp (-8) to 1.67×10 exp (-6) ㎠/sec for initial concentration change, and from 6.09×10 exp (-7) to 3.98×10 exp (-6) ㎠/sec for reaction temperature change. Activation energy during the diffusion was calculated as 36 ㎉/㏖.
        38.
        1998.02 KCI 등재 서비스 종료(열람 제한)
        Ion exchange performance to remove nitrate in water was studied using commercially available strong base anion exchange resin of Cl^- type in the batch and continuous column reactors. The performance was tested using the effluent concentration histories for continuous column or equilibrium concentrations for batch reactor as a function of time until resins were exhausted or reached ionic equilibrium between resin and solution. Anion exchange resin used in this study was more effective than activated carbon or zeolite for nitrate removal. With large resin amount or low initial concentration, nitrate removal characteristics for a typical gel-type resin was increased. On considering the relation between the breakthrough capacity and nitrate concentration of the influent, the use of anion exchange resin were suitable for the higher order water treatment. The nitrate removal of above 90% could be possible until the effluent of above 650 BV was passed to the column. Thus, the commercially available strong base anion exchange resin of Cl^- type used in this study could be effectively used as economic material for treatment of the groundwater. The breakthrough curves showed the sequence of resin selectivity as SO_4^2- > NO_3, > NO^2- > HCO_3^-. The results of this study could be scaled up and used as a design tool for the water purification system of the real groundwater and surface water treatment processes.
        1 2