• 한국방사선학회논문지
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• 제8권1호
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• pp.19-26
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• 2014

본 논문에서는 프랙탈 부호화시 변환식의 계수를 찾는 과정에서 블럭의 탐색영역을 줄이기 위해 탐색영역인 도메인 블럭의 특성을 화소의 밝기의 평균에 의한 클래스와 분산에 의한 클래스로 분류하여 리스트를 구성한 후 레인지 블럭과 같은 클래스를 가지는 도메인 블럭만 검색하도록 하면서 도메인 블록 탐색시 1차 허용 오차 한계값을 제어하여 리스트 탐색시 RMS값에 일정 허용오차 이내의 값을 가지면 리스트를 끝까지 탐색하지 않고 변환값을 결정하도록 하여 부호화 시간을 향상시켰다. 또한 퀴드트리 분할법으로 레인지 블럭의 크기를 가변시켜 변환($w_i$)의 수를 줄임으로서 압축효율을 높이고 도메인 레인지 블럭의 크기에 따라 탐색 영역의 탐색 밀도와 허용오차를 변화시켰을 때 화질 개선 여부를 검토하였다. 제안된 방법으로 부호화한 결과 부호화 시간은 허용오차의 범위에 따라 향상되며 압축효과는 높아 졌고 PSNR값은 다소 떨어졌으나 거의 무시할 수 있을 정도의 변화가 있었다.

• 한국환경과학회지
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• 제19권5호
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• pp.549-563
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• 2010

The environmental behaviors of polycyclic aromatic hydrocarbons (PAHs) are mainly governed by their solubility and partitioning properties on soil media in a subsurface system. In surfactant-enhanced remediation (SER) systems, surfactant plays a critical role in remediation. In this study, sorptive behaviors and partitioning of naphthalene in soils in the presence of surfactants were investigated. Silica and kaolin with low organic carbon contents and a natural soil with relatively higher organic carbon content were used as model sorbents. A nonionic surfactant, Triton X-100, was used to enhance dissolution of naphthalene. Sorption kinetics of naphthalene onto silica, kaolin and natural soil were investigated and analyzed using several kinetic models. The two compartment first-order kinetic model (TCFOKM) was fitted better than the other models. From the results of TCFOKM, the fast sorption coefficient of naphthalene ($k_1$) was in the order of silica > kaolin > natural soil, whereas the slow sorbing fraction ($k_2$) was in the reverse order. Sorption isotherms of naphthalene were linear with organic carbon content ($f_{oc}$) in soils, while those of Triton X-100 were nonlinear and correlated with CEC and BET surface area. Sorption of Triton X-100 was higher than that of naphthalene in all soils. The effectiveness of a SER system depends on the distribution coefficient ($K_D$) of naphthalene between mobile and immobile phases. In surfactant-sorbed soils, naphthalene was adsorbed onto the soil surface and also partitioned onto the sorbed surfactant. The partition coefficient ($K_D$) of naphthalene increased with surfactant concentration. However, the $K_D$ decreased as the surfactant concentration increased above CMC in all soils. This indicates that naphthalene was partitioned competitively onto both sorbed surfactants (immobile phase) and micelles (mobile phase). For the mineral soils such as silica and kaolin, naphthalene removal by mobile phase would be better than that by immobile phase because the distribution of naphthalene onto the micelles ($K_{mic}$) increased with the nonionic surfactant concentration (Triton X-100). For the natural soil with relatively higher organic carbon content, however, the naphthalene removal by immobile phase would be better than that by mobile phase, because a high amount of Triton X-100 could be sorbed onto the natural soil and the sorbed surfactant also could sorb the relatively higher amount of naphthalene.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.271-279
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• 2004

The aroma component of Hallabong peel has been characterized by GC-MS with two different extraction techniques: solid-phase trapping solvent extraction (SPTE) and headspace solid-phase microextraction (HSSPME). Aroma components emitted from Hallabong peel were compared with those of other citrus varieties: lemon, orange and grapefruit by SPTE and GC-MS. d-Limonene (96.98%) in Hallabong was the main component, and relatively higher peaks of cis- ${\beta}$-ocimene, valencene and -farnesene were observed. Other volatile aromas, such as sabinene, isothujol and ${\delta}$-elemene were observed as small peaks. Also, principal components analysis was employed to distinguish citrus aromas based on their chromatographic data. For HSSPME, the fiber efficiency was evaluated by comparing the partition coefficient ($K_{gs}$Kgs) between the HS gaseous phase and HS-SPME fiber coating, and the relative concentration factors (CF) of the five characteristic compounds of the four citrus varieties. 50/30 ${\mu}$m DVB/CAR/PDMS fiber was verified as the best choice among the four fibers evaluated for all the samples.

• Journal of Korean Society for Atmospheric Environment
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• 제22권E1호
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• pp.35-43
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• 2006

Ambient particle size distributions of PCBs and their dry deposition fluxes were measured at a site in Seoul to quantify dry deposition fluxes of PCBs and size characteristics of PCBs in the air, and to estimate ambient concentrations of gaseous PCBs and dry deposition fluxes. The dry deposition plate was used to measure dry deposition fluxes of particulate mass and PCBs and a cascade impactor and rotary impactor were used to measure ambient particle size distributions for small ($D_p<9{\mu}m$) and large ($D_p>9{\mu}m$) particles, respectively. Six sample sets were collected from April to July 1999. The fluxes of particulate total PCBs (the sum of 43 congeners) ranged from 160 to $607ng\;m^{-2}day^{-1}$. The size distribution of total PCBs was bimodal with two peaks in small particle size ($D_p{\sim}0.6\;and\;6{\mu}m$, respectively) and, thus, mass concentration being dominant in small particles. The mean particulate PCBs concentration was $6.9{\mu}g$ PCBs/g. The concentrations of PCB homologues in the gas phase were estimated based on the particle/gas partition coefficient ($K_p$) with the measured values of particulate PCBs in this study and they were comparable to those observed in other previous studies. Dry deposition fluxes were estimated by calculating dry deposition velocities.

• 정보처리학회논문지D
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• 제9D권2호
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• pp.259-266
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• 2002

소프트웨어 개발시 중요하게 제기되는 문제점으로 소프트웨어 생명주기의 초기단계에서 개발에 투입될 노력과 비용을 추정하는 능력이다. 측정된 소프트웨어 규모인 기능점수 (FP, Function Point)로부터 프로젝트 개발에 소요되는 노력과 비용을 추정하는 회귀모델들이 제안되었다. 그러나 이들 제안된 모델들은 사용한 표본의 크기가 작고, 과거에 개발된 프로젝트를 대상으로 하고 있다. 1990년대에 개발된 789개 소프트웨어 개발 프로젝트들에 투입된 개발노력에 이들 모델을 적용한 결과 결정계수 $R^2$가 0.53 이하로 데이터의 변동을 설명하였다. 본 논문은 프로젝트 인도율(PDR)을 이용하여 동질성을 갖는 그룹으로 분류하여 개발노력을 추정하는 모델을 제안하였다. 제안된 모델은 랜덤한 잔차 분포를 갖고 있고, 대부분의 PDR 범위에서 0.99이상의 결정계수로 데이터의 변동을 설명하였다.

• 대한화장품학회지
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• 제30권4호
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• pp.471-477
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• 2004

피부 세포는 외부의 유해 요소 즉, 스트레스 환경에 노출되었을 때 세포 자신을 보호하기 위하여 다양한 방어 및 복구 체계를 가지고 있는데 그 중 하나가 보호단백질인 열충격단백질 70 kDa의 발현이다 Glucuronic acid를 피부세포에 다양한 농도로 전처리한 다음 유해자극(열, 활성산소)을 주었을 경우, western blottting을 통해 $0.12\%$ 농도에서 세포 내 열충격단백질이 발현됨을 알 수 있었다 그리고 confocal microscopy 및 세포생존율 실험을 이용하여 열 및 활성 산소에 대한 우수한 세포보호 효과를 확인하였다. 또한 마우스 피부를 이용하여 glucuronic acid 및 수중유(O/W)형 에멀젼에 적용하였을 때 경피 흡수 양상을 비교한 결과, glucuronic acid는 빠른 경피흡수거동을 보였다(투과속도 $0.83114 mg/cm^2/h,$ 지연시간 1.2 h, 분배계수 0.114). 에멀젼에서는 투과속도는 $0.04153{\;}{\mu}g/cm^{2}/h,$ 누적투과량은 $1456.25{\;}{\mu}g/cm^{2}$로 감소하였지만 지연시간은 2.48 h으로 증가하였고 지속적인 경피흡수(서방성)를 보였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권5호
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• pp.20-28
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• 2021

Perfluorinated compounds(PFCs), an emerging environmental pollutant, are environmentally persistent and bioaccumulative organic compounds that possess a toxic impact on human health and ecosystems. PFCs are distributed widely in environment media including groundwater, surface water, soil and sediment. PFCs in contaminated solid can potentially leach into groundwater. Therefore, understanding PFCs partitioning between the aqueous phase and solid phase is important for the determination of their fate and transport in the environment. In this study, the sorption equilibrium batch and kinetic experiment of PFCs were carried out to estimated the sorption coefficient(K_d) and the fraction between aqueous-solid phase partition, respectively. Sorption branches of the PFDA(Perfluoro-n-decanoic acid), PFNA(Perfluoro-n-nonanoic acid), PFOA(Perfluoro-n-octanoic acid), PFOS(Perfluoro-1-octane sulfonic acid) and PFHxS(Perfluoro-1-hexane sulfonic acid) isotherms were nearly linear, and the estimated K_d was as follow: PFDA(1.50) > PFOS(1.49) > PFNA(0.81) > PFHxS(0.45) > PFOA(0.39). The sorption kinetics of PFDA, PFNA, PFOA, PFOS and PFHxS onto soil were described by a biexponential adsorption model, suggesting that a fast transport into the surface layer of soil, followed by two-step diffusion transport into the internal water and/or organic matter of soil. Shorter times(<20hr) were required to achieve equilibrium and fraction for adsorption on solid(F₁, F₂) increased with perfluorinated carbon chain length and sulfonate compounds in this study. Overall, our results suggested that not only the perfluorocarbon chain length, but also the terminal functional groups are important contributors to electrostatic and hydrophobic interactions between PFCs and soils, and organic matter in soils significantly affects adsorption maximum capacity than kinetic rate.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권1호
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• pp.66-72
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• 2010

The partitioning tracer method is to estimate the residual saturation of nonaqueous phase liquid (NAPL) in soils by analyzing tracer's retardation induced by the reversible partitioning of tracer with NAPL. This study is to estimate the residual diesel saturation in soils using the partitioning tracer method. Two-dimensional soil box was used to represent the 2-dimensional flows of groundwater and tracer solution in the saturated aquifer, and the soil box was filled with soil and then saturated with water. The residual diesel saturation was induced in saturated soil, and the partitioning tracer method was applied. The results from batch-partitioning experiment indicated that the diesel-water partitioning was linear with respect to tracer's concentration, and the partition coefficient of tracer between diesel and water was measured by their linearities. The groundwater flow in the saturated aquifer was simulated in the 2-dimensional soil box, and the residual diesel contamination was visually identified. The results from the partitioning tracer method with or without diesel in soils confirmed that 4-methyl-2-pentanol, 2-ethyl-1-butanol and 1-hexanol, can be used as a detecting method for diesel contamination. By the accuracies of estimations for diesel contamination using the partitioning tracer method, 2-ethyl-1- butanol showed the highest accuracy with 83%.

• 한국물환경학회지
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• 제20권5호
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• pp.512-519
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• 2004

Hybrid barriers using reduction and immobilization were tested to remediate the groundwater contaminated with multi-pollutants in this study. Iron filings and HDTMA(hexadecyltrimethylammonium)-bentonite were simulated in columns to assess the performance of hybrid barriers for remediation of trichloroethylene(TCE)-contaminated water. TCE reduction rate for the mixture of iron filings and HDTMA-bentonite was about 7 times higher than that for iron filings, only suggesting the reduction of TCE was accelerated when HDTMA-bentonite was mixed with iron filings. TCE reduction rate for the two layers of iron and HDTMA-bentonite was nearly similar to that for iron filings alone, but the partition coefficient($K_d$) for the two layers was 4.5 times higher than for that iron filings only. TCE was immobilized in the first layer with HDTMA-bentonite, and then dechlorinated in the second layer with iron filings. HDTMA-bentonite may contribute to the increase in TCE concentration on iron surface so that more TCE can be reduced. Also, TCE removal in the hybrid barriers was not affected by chromate and naphthalene while the reduction rate of TCE with the co-existing contaminants by iron filings was significantly decreased. Significant TCE removal in this research indicates that the proposed hybrid barrier system has the potential to become the effective remediation alternative during the occurrence of oil shock. Also, if subsurface environments are contaminated with multi-pollutants that contain non-reducible compounds as well as reducible compounds such as TCE, the conventional reactive barriers cannot be applied to this subsurface environment, while the proposed hybrid system can be applied successfully.

• Journal of Pharmaceutical Investigation
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• 제25권4호
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• pp.353-363
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• 1995

The purpose of this study was to investigate the intestinal and nasal absorption enhancement of cefotaxime (CTX) by ion-pairing with counterions and to design an effective oral and intranasal drug delivery system for antibiotics. Counterions for absorption promotion were cationic surfactants [cetylpyridinium chloride (CP), cetrimide (CT) and benzalkonium chloride (BA)]. In the presence of counterions, the apparent partition coefficient of cefotaxime was increased depending on the molar concentration of the counterions. Anion interference was observed for ion-pairing of cefotaxime with counterions because of the counterbalance between an anion and counterions. The present study employed the in situ simultaneous nasal and intestinal perfusion technique in rats. The apparent permeabilities $(P_{app})$ of cefotaxime were $1.43{\pm}0.04{\times}10^{-5}\;cm/sec(mean{\pm}S.E)$ in the nasal cavity and 0 in the jejunum, respectively, which indicated that the intrinsic absorptivity of cefotaxime was greater in the nasal cavity than in the jejunum. When ionupairing formers were used, the decreasing order of apparent cefotaxime permeability $(P_{app},\;10^{-5}\;cm/sec)$, corrected for surface area of absorption, was as followings: $BA\;(7.50{\pm}0.36)\;>\;CT\;(4.92{\pm}0.24)\;>\;CP\;(3.01{\pm}0.17)$ in the jejunum and $BA\;(22.31{\pm}1.36)\;>\;CP\;(18.24{\pm}0.81)\;>\;CT \;(16.22{\pm}1.87)$ in the nasal cavity. The increase in permeability of cefotaxime was about 13-fold in the rat nasal cavity and was marked in the rat jejunum for ion-pairing with counterions as compared to those without ion-pairing. The damages of jejunal and nasal mucosal membrane by counterions were observed within approximately 2hrs after removal of ion-pair of cefotaxime with counterions from the nasal cavity and jejunum. These results suggest that CP can be used as an ion-pairing former in the jejunum and CP and CT can be used as ion-pairing formers in the nasal cavity for cefotaxime, as well as for poorly absorbed drugs with a negative charge due to ionization.