• 한국환경보건학회지
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• 제39권4호
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• pp.360-368
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• 2013

Objectives: Phthalates are used in a large variety of products including as coatings of pharmaceutical tablets, film formers, stabilizers, dispersants, emulsifying agents, and suspending agents. They have been the subject of great public concern in recent years. The extensive uses of this material have attracted attention and issues regarding its safety have been raised. Methods: In this study, three types of phthalate skin permeation were studied using matrixes such as ointments, creams and lotions in vitro. The absorption of phthalate diesters [Dimethyl phthalate (DMP), Di-n-propyl phthalate (DPP) and Di-n-pentyl phthalate (DNPP)] using film former has been measured in vitro through rat skin. Epidermal membranes were set up in Franz diffusion cells and their permeability to PBS measured in order to establish the integrity of the skin before the phthalates were applied to the epidermal surface. Results: Absorption rates for each phthalate ester were determined and permeability assessment made to quantify any irreversible alterations in barrier function due to contact with the esters. Types of phthalate in vitro experimental results quickly appeared in the following order DMP > DPP ${\geq}$ DNPP. Conclusions: In the experimental results, lotion> cream> ointment, and the permeation rate of lotion with a great amount of moisture was the fastest. Skin permeation rate is generally influenced by the chemical characteristics of a given chemical, such as molecular weight and lipophilicity. As the esters became more lipophilic and less hydrophilic, the rate of absorption decreased.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.441-441
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• 2012

Franz Keldysh Oscillation (FKO)은 p-n 접합 구조의 Photoreflectance (PR) spectra에서 표면 및 계면의 전기장(electric field) 특성을 반영한다. InAs/GaAs 양자점 태양전지(Quantum Dot Solar Cell, QDSC) 구조에서 InAs 양자점 층 전후에 AlGaAs 층을 삽입하여 퍼텐셜 장벽(potential barrier) 두께에 따른 PR spectra 및 GaAs-matrix에서 FKO 주파수 특성을 비교 분석하였다. InAs/GaAs 양자점 태양전지는 p-i-n 구조의 i-GaAs에 2.0 monolayer (ML), 8주기의 InAs 양자점 층을 삽입하여 Molecular Beam Epitaxy (MBE) 방법으로 성장하였다. 각 양자점 층 전후에 두께가 각각 0.0, 1.6, 2.8, 6.0 nm인 AlGaAs 층을 삽입하여 퍼텐셜 장벽 두께에 따른 FKO 주파수 변화를 관측하였다. 또한 태양전지 구조의 전기장 분포를 좀 더 용이하게 관측하기 위해 여기 광의 세기(power intensity)를 충분히 낮추어 Photovoltaic effect에 의한 내부 전기장의 변화를 최소화하여 비교 분석하였다. InAs/GaAs 양자점 태양전지 구조에서 AlGaAs 장벽층이 없는 경우, PR spectra의 Fast Fourier Transform 결과에 반영되는 FKO 주파수 특성은 p-i-n 구조 계면에서 공핍층(depletion region)의 space charge field보다 양자점 층의 내부 전기장에 의한 FKO 주파수가 더 큰 진폭(amplitude)을 보였다. 반면에, AlGaAs 장벽층이 삽입되면 두께가 커짐에 따라 p-i-n 구조 계면의 space charge field에 의해 더 큰 진폭의 FKO 주파수가 관측되었다. 이는 AlGaAs 장벽층이 삽입됨으로써 양자점 층 내 양자 상태 수 및 여기광에 의한 캐리어의 수와 관련이 있음을 확인하였으며, 결과적으로 GaAs-matrix에서 p-i-n 구조 계면의 space charge field에 영향을 미치게 됨을 알 수 있다. 이러한 PR 특성 결과들을 InAs/GaAs 양자점 태양전지의 설계 및 제조에 반영함으로써 양자효율 증대에 기여할 것으로 기대된다.

• Journal of Pharmaceutical Investigation
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• 제38권5호
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• pp.319-323
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• 2008

For transdermal delivery of ceramides, various liposomes formulations were studied and evaluated. Sodium deoxycholate (SDC), Tween 20 and Span 85 were used as edge activators. The skin permeation of ceramides was performed using a Franz cell apparatus with hairless mouse skin. Among edge activators, SDC showed the higher values of deformability index and skin permeation than did others. For optimization of formulations, we varied the ratios of lipids to edge activators and the compositions between phosphatidylcholine (PC) and ceramides. The optimal ratio of lipid to SDC was observed to be 6:1 (w:w) and that of PC and ceramide was 1:1. Our results suggest that the skin permeation of ceramides could be enhanced by optimized deformable formulations of liposomes containing SDC as a major edge activator.

• Structural Engineering and Mechanics
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• 제12권4호
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• pp.363-376
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• 2001

Sandwich plates are widely used in lightweight design due to their high strength and stiffness to weight ratio. Due to the heterogeneous structure of sandwich plates, they can exhibit local instabilities (wrinkling), which lead to a sudden loss of stiffness in the structure. This paper presents an analytical solution to the wrinkling problem of sandwich plates. The solution is based on the Rayleigh-Ritz method, by assuming an appropriate deformation field. In contrast to the other approaches up to now, this model takes arbitrary and different orthotropic face layers, finite core thickness and orthotropic core material into account. This approach is the first to cover the wrinkling of unsymmetric sandwiches and sandwiches composed of orthotropic FRP face layers, which are most common in advanced lightweight design. Despite the generality of the solution, the computational effort is kept within bounds. The results have been verified using other analytical solutions and unit cell 3D FE calculations.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.296.1-296.1
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• 2003

Purpose. External gel formulations of prostaglandin E1 ethyl ester (PGE1-EE), a prod rug of PGE1 as a therapeutic agent for erectile dysfunction, were tried and evaluated by in vitro skin penetration characteristics and in vivo pharmacodynamic effects in cat. Method. The in vitro skin penetration was performed with Franz diffusion cell and examined in aspects of alcohol/polyol ratios and various enhancers. (omitted)

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.236.2-236.2
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• 2003

For the purpose to treatment of skin disease genipoiside and hydrolyzed product of Gardeniae Fructus were studied on skin permeation and crosslinking of a biologied tissue. Geniposide was hydrolyzed to genipin by ${\beta}$-glucosidase and the rate of hydrolysis was rapid on the condition of high temperature of medium and high concentration of ${\beta}$-glucosidase. The permeation enhancing effects of geniposide and genipin under cream and gel preparations were tested using Franz type diffusion cell and the skin of hairless mouse. (omitted)

• 한국응용과학기술학회지
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• 제24권4호
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• pp.410-415
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• 2007

Functional cosmetics are intensively investigated for the effectiveness of skin whitening, anti-aging and slimming. For enhancing the effectiveness, active ingredients should be delivered into the cell in the dermis. The amounts of penetration of caffeine and $Arbutin^{(R)}$ were tested, in vitro, using Franz diffusion cell. Oil-in-water emulsions were used for the vehicles of the transport. For the measuring the amounts of active ingredients delivered into the dermal skin, tape stripping was done after finishing the penetration experiments. The amounts of delivered caffeine were $8.45{\pm}$ 1.26ug/ml before tape stripping and $3.45{\pm}$ 1.80ug/ml after tape stripping, however, the amounts of delivered $Arbutin^{(R)}$ was quite small to detect. From now on, proper vehicles are considered for enhancing the delivery of $Arbutin^{(R)}$ Hairless mouse skin was compared with pig skin as a transdermal delivery membrane. The aspects of delivery were similar, but the amount of delivered ingredients using pig skin was larger than that of using hairless mouse skin. Therefore, the pig skin would be considered as a membrane for drug delivery experiments.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.429-429
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• 2012

본 연구에서는 분자선 박막 성장법(MBE)으로 성장된 GaAs single junction solar cell의 광학적 특성 변화를 photoreflectance (PR)을 이용하여 연구하였다. 본 연구에 사용된 태양전지 구조는 n+-GaAs (100)기판 위에 n+-GaAs buffer를 200 nm 성장 후 그 위에 i-GaAs 250 nm와 p+-GaAs 200 nm 성장 하였다. 상온에서 PR 측정 결과, 변조빔 세기가 증가할수록 Franz-Keldysh oscillation (FKO)의 주파수가 증가하는 현상이 관측되었다. 이는 변조빔의 세기가 강해질수록 광케리어수의 증가로 인한 스크리닝 효과에 기인한 것으로 사료된다. 아울러 Fast Fourier transform (FFT) 결과, 변조빔의 세기가 약할 때는 세 개의 주된 피크가 나타났으며, 이러한 현상은 GaAs에서 가전자대의 heavy hole (HH)과 light hole (LH)의 전이로 인해 나타나는 FKO 신호가 중첩되어 HH과 LH 피크가 HH과 HH-,LH과 LH-로 나뉘어진 것으로 사료된다. 여기광의 세기가 $1.40mW/cm^2$ 이상일 때는 주된 세 개 피크 이외에 부가적인 피크가 상대적으로 고 주파수 영역에서 관측되었다. 이러한 고주파수 영역에서의 나타나는 FKO 주파수는 시료의 내부전기장이 여기광의 세기가 증가할수록 감소하는 결과로 사료된다.

• 대한화장품학회지
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• 제45권2호
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• pp.175-184
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• 2019

상피세포성장인자(epidermal growth factor, EGF)는 인간의 표피 및 진피에서 세포막 수용체와 상호작용을 통하여 세포의 생장 및 증식을 유도하는 기능을 갖고 있다. 이 같은 EGF의 기능은 의료 및 화장품 분야에서 상처치유 의약품 및 노화방지 화장품의 주요원료로 사용되고 있다. 화장품 원료로서 EGF는 피부장벽으로 알려져 있는 피부 각질층의 투과가 잘 안되기 때문에 가지고 있는 본연의 효능을 구현하는 데 문제가 있다. 본 연구에서는 EGF의 경피투과 효율을 개선하기 위하여 피부 투과능이 확인된 거대분자 전송 도메인(macromolecule transduction domain, MTD) 151이 융합된 형태로 재조합 인간 상피세포성장인자 ($MTD_{151}-EGF$)를 개발하였다. $MTD_{151}-EGF$의 유전자가 coding된 vector로 형질전환된 대장균에서 $MTD_{151}-EGF$ 발현시킨 후 정제를 진행하였다. 정제된 MTD-EGF를 대상으로 세포증식시험, 세포독성시험, 생체외 피부흡수시험 그리고 인공피부를 이용한 경피투과능을 평가하였다. 99% 이상 고순도로 정제된 $MTD_{151}-EGF$의 세포증식 활성은 EGF 대비 동등 이상의 수준이었으며, 세포독성은 관찰되지 않았다. 또한, 인공피부 투과모델에서 FITC로 표지된 EGF와 $MTD_{151}-EGF$의 진피층까지의 투과를 공초점 현미경으로 관찰한 결과, $MTD_{151}-EGF$는 EGF 대비 우수한 투과능을 보였으며, 경피흡수 시스템을 이용한 투과물질의 정량분석 결과, EGF 대비 약 16 배 이상 투과량이 많은 것으로 확인되었다. 이러한 결과들은 다양한 활성물질들의 화장품용 원료로서의 경피투과에 MTD가 기존의 물리적인 경피투과 방법을 효율적으로 개선한 대안이 될 것으로 판단된다.

• International Journal of Stem Cells
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• 제16권3호
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• pp.293-303
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• 2023

Background and Objectives: The physiological oxygen tension in fetal brains (~3%, physioxia) is beneficial for the maintenance of neural stem cells (NSCs). Sensitivity to oxygen varies between NSCs from different fetal brain regions, with midbrain NSCs showing selective susceptibility. Data on Hif-1𝛼/Notch regulatory interactions as well as our observations that Hif-1𝛼 and oxygen affect midbrain NSCs survival and proliferation prompted our investigations on involvement of Notch signalling in physioxia-dependent midbrain NSCs performance. Methods and Results: Here we found that physioxia (3% O₂) compared to normoxia (21% O₂) increased proliferation, maintained stemness by suppression of spontaneous differentiation and supported cell cycle progression. Microarray and qRT-PCR analyses identified significant changes of Notch related genes in midbrain NSCs after long-term (13 days), but not after short-term physioxia (48 hours). Consistently, inhibition of Notch signalling with DAPT increased, but its stimulation with Dll4 decreased spontaneous differentiation into neurons solely under normoxic but not under physioxic conditions. Conclusions: Notch signalling does not influence the fate decision of midbrain NSCs cultured in vitro in physioxia, where other factors like Hif-1𝛼 might be involved. Our findings on how physioxia effects in midbrain NSCs are transduced by alternative signalling might, at least in part, explain their selective susceptibility to oxygen.