• 혜화의학회지
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• 제16권2호
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• pp.267-280
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• 2007

Gupoongjeseuptang(GPJST) is a traditional herbal medicine used for the treatment of dermatitis. The aim of this study was to confirm whether or not GPJST has a preventive effect on development of atopic dermatitis in dinitrochlorobenzene(DNCB)-applied Nc/Nga mouse. This study was undertaken to develop a reliable mouse model demonstrating similar immunologic phenomena as human atopic dermatitis characterized with predominance of type-2 immune response. NC/Nga mouse were sensitized with $200\;{\mu\ell}$ of 1% 2,4-dinitrochlorobenzene(DNCB) (acetone : olive oil = 3 : 1 mixture) and challenged twice or three times with $150\;{\mu\ell}$ of 0.2% DNCB in a week for the following 4 weeks. GPJST was administered orally to Nc/Nga mouse for 6 weeks, which led to the remarkable suppression on the development of dermatitis, as determined by various immune factors related to pathogenesis of atopic dermatitis in splenocytes and DLN cells. In this study, GPJST selectively suppressed T ce11 (CD4+, CD3+CD69+, CD4+CD25+) activation, which may be essential for ratio of IL-4 versus INF-$\gamma$ produced in the splenic T cell culture supernatants was approximately 3-fold higher in the mouse treated with DNCB than their control mouse respectively. Immunologic studies showed down-regulated that the capacity of spleen T cells to produce IL-4, but IFN-$\gamma$ was up-regulated by means of oral intake of these GPJST. These results strongly suggest that GPJST is a promising candidate for treatment of human atopic dermatitis.

• KSBB Journal
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• 제15권5호
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• pp.469-473
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• 2000

본 연구는 실험실 규모의 biofilter를 이용하여 공기 중에 혼합되어 있는 대표적인 휘발성 유기화합물인 toluene기체를 제거하는 실험이다. 생물여과실험은 일반적인 조건하에서 오 염된 공기를 바이오필터의 상단으로부터 하단으로 흐르게 하 여 수행하였다. 반웅기 컬럼의 내부는 peat와 calstone (부피 비 5:3) 혼합물로 충진 되었으며, 충진재는 반응기에 채우기 전에 미생물 (Pseudomonas putida type A)과 잘 혼합하였다. 접종된 미생물은 충진 고체충에 고정화되어 생물막을 형성하 게 된다. 바이오필터는 다양한 툴루엔 농도와 유속조건에서 약 90일 이상 운전 되었으며, 최대 제거량은 유입 toluene량 $30 g/m^3hr$에서 $20 g/m^3hr$임을 알 수 있었다. 오염왼 공기는 체류시간 1-2 min에서 제거율이 20-90%끼지 변화하는 것을 보여 주었다 한편 운전중에 발생하는 압력강하는 $1.062 cmH_2O/m$ 정도로서 반응기 전체를 통하여 무시할 수 있을 정도로 낮았다.

• 한국항공우주학회지
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• 제37권10호
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• pp.1038-1047
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• 2009

추력 30톤급 펌프공급방식 액체로켓엔진을 위한 가스발생기 개발 과정에 관하여 기술하였다. 액체산소와 케로신을 추진제로 연료 과농 조건에서 작동하는 가스발생기의 개발을 위해 분사기 개발에서부터 시작하여 축소형, 실물형 개발시제를 거쳐 가스발생기 단품 개발을 성공적으로 완료하였다. 가스발생기 설계 과정에서 다양한 해석적 방법을 적용하였으며 점화 시험, 연소성능 및 연소안정성 평가시험, 내구성 평가시험 등을 통해 가스발생기의 성능요구사항을 시험적으로 검증하였다. 개발된 가스발생기는 연소압 및 혼합비 운용 영역 내에서 안정적으로 작동하며 성능 및 수명 요구조건을 만족시킴을 확인하였다.

• 한국재료학회지
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• 제20권3호
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• pp.167-173
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• 2010

In this study, we used activated carbon (AC) and titanium oxysulfate as a titanium precursor to prepare carbon/titania composites. We then mixed it with bentonite in different ratios to make a carbon/titania/bentonite monolith for use in architecture bricks by using Phenolic rosin (PR) as a bonding agent. The physicochemical properties of the prepared composites were analyzed by BET surface area, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), self-cleaning effect and bactericidal tests. The BET surface areas increased as the ratio of carbon/titania composites increased. The SEM microscopy showed that the $TiO_2$ and bentonite were coated on the surface of the AC. The XRD patterns showed a mixture structure of anatase and rutile of $TiO_2$ with a clear $SiO_2$ structure. The EDX spectra of the carbon/titania/bentonite monolith confirmed the presence of various elements, namely C, O, Ti and Si, as well as other, impure elements. Moreover, to determine the self-cleaning effect of the carbon/titania/bentonite monolith, we used methylene blue (MB, $C_{16}H_{18}N_3S{\cdot}Cl{\cdot}3H_2O$) in an aqueous solution under the irradiation of visible light. Accordingly, all of the samples had excellent degradation of the MB solution. Furthermore, it was observed that the composites with sunlight irradiation had a greater effect on E. coli than any other experimental conditions.

• 한국응용과학기술학회지
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• 제14권3호
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• pp.23-28
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• 1997

N-도데카노닐-N-메틸 아미도 폴리올 카르복시알킬 에테르(DGC)/N-도데카노실-N-알킬글루카민(DG)/물 혼합계에서의 상도를 편광현미경, 시차주사열량계(DSC) 및 레올로지를 이용하여 관찰하였다. 편광현미경으로 계면활성제 농도와 온도의 함수로써 얻어지는 액정상의 형태를 관찰할 수 있었고, DSC측정에 의해서는 비등방성 액정과 등방성 액체 사이의 상전이를 관찰할 수 있었다. 헥사고날과 라멜라 액정상 사이에서 레올로지에 의해 측정된 계면활성제 수용액의 점탄성은 편광현미경과 시차주사열량계에서 얻은 결과와 일치됨을 확인할 수 있었다. DGC/DG(5:5 몰비)/물계의 상에 대하여 조사한 결과, 25${\sim}$65wt% 사이에서는 큐빅 액정상, 70wt% 이상에서는 라멜라 액정상이 나타남을 알 수 있었다.

• 방사선산업학회지
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• 제6권2호
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• pp.153-158
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• 2012

In this research, poly(acrylic acid) (PAAc) hydrogels containing zinc oxide particle were prepared by gamma-ray irradiation. PAAc powder was completely dissolved in distilled water at room temperature. Water-insoluble zinc oxide powder were added into the PAAc solution and stirred until totally dissolved. Finally, the mixture was irradiated by gamma-ray irradiation to make crosslinking. The effects of various parameters such as zinc ions' concentration, irradiation doses were varied and investigated in detail. PAAc hydrogels containing zinc oxide particle were characterized by gel content and swelling ratio. Moreover, the antibacterial properties of this material were evaluated by paper diffusion test against the Gram positive and Gram negative bacteria.

• Steel and Composite Structures
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• 제33권4호
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• pp.509-523
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• 2019

In the present work, the buckling analysis of micro sandwich plate with an isotropic/orthotropic cores and piezoelectric/polymeric nanocomposite face sheets is studied. In this research, two cases for core of micro sandwich plate is considered that involve five isotropic Devineycell materials (H30, H45, H60, H100 and H200) and an orthotropic material also two cases for facesheets of micro sandwich plate is illustrated that include piezoelectric layers reinforced by carbon and boron-nitride nanotubes and polymeric matrix reinforced by carbon nanotubes under temperature-dependent and hydro material properties on the elastic foundations. The first order shear deformation theory (FSDT) is adopted to model micro sandwich plate and to apply size dependent effects from modified strain gradient theory. The governing equations are derived using the minimum total potential energy principle and then solved by analytical method. Also, the effects of different parameters such as size dependent, side ratio, volume fraction, various material properties for cores and facesheets and temperature and humidity changes on the dimensionless critical buckling load are investigated. It is shown from the results that the dimensionless critical buckling load for boron nitride nanotube is lower than that of for carbon nanotube. It is illustrated that the dimensionless critical buckling load for Devineycell H200 is highest and lowest for H30. Also, the obtained results for micro sandwich plate with piezoelectric facesheets reinforced by carbon nanotubes (case b) is higher than other states (cases a and c).The results of this research can be used in aircraft, automotive, shipbuilding industries and biomedicine.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.367-376
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• 2012

연소불안정 현상을 제거하거나 효과적으로 제어하기 위해서는 화염구조에 대한 이해가 매우 중요하다. 이에 본 연구에서는 OH 자발광 및 He-Ne 레이저 광흡수 계측기법을 이용하여 연소불안정과 화염구조사이의 상관관계에 대한 실험적 연구를 다양한 실험조건에서 수행하였다. 실험에서는 673K로 가열되어진 swirl 형태로 공급되는 건조한 공기와 LNG(CH4) 연료를 사용하였으며 전체 당량비는 1.2 조건에서 속도를 25 ~ 70 m/s까지 바꾸어가며 실험을 수행하였다. 이를 통하여 연소불안정 현상이 낮은 속도조건과 높은 속도조건에서 발생하는 것을 확인할 수 있었고, 낮은 속도조건의 불안정에서는 화염의 와동구조가 연소불안정현상에 영향을 끼친다는 것을 알 수 있었다.

• 한국추진공학회지
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• 제22권5호
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• pp.125-131
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• 2018

다단연소사이클 엔진의 추진제는 예연소기에서 일부 연소되고, 연소된 고온의 가스는 터빈을 구동하고 터빈은 터보펌프를 작동시킨다. 터보펌프의 터빈을 통과한 연소가스는 고온 고압의 상태로 연소기로 공급되는데, 이때 연료 또는 산화제의 양에 따라 연소가스는 연료 과잉 또는 산화제 과잉 상태로 공급된다. 산화제 과잉상태의 환경에서 금속 배관은 작은 입자의 충격에 의해서도 발화 또는 폭발될 수 있다. 이를 방지하기 위해 로켓 선진 국가에서는 산화제가 이동하는 공간에 내산화 코팅을 한다. 본 연구에서는 해외 내산화 코팅 물질 분석을 통해 국산 조합분말을 개발하였고 내산화 코팅 공정을 확립하였다.

• Structural Engineering and Mechanics
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• 제87권6호
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• pp.529-540
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• 2023

A novel laminated-hybrid-composite-beam (LHCB) of glass-epoxy infused with flyash and graphene is constructed for this study. The conventional mixture-rule and constitutive-relationship are modified to incorporate filler and lamina orientation. Eringen's non-local-theory is used to include the filler effect. Hamilton's principle based on fifth-order-layer-wise-shear-deformation-theory is applied to formulate the equation of motion. The analogous shear-spring-models for LHCB with multiple-cracks are employed in finite-element-analysis (FEA). Modal-experimentations are conducted (B&K-analyser) and the findings are compared with theoretical and FEA results. In terms of dimensionless relative-natural-frequencies (RNF), the dynamic-response in cantilevered support is investigated for various relative-crack-severities (RCSs) and relative-crack-positions (RCPs). The increase of RCS increases local-flexibility in LHCB thus reductions in RNFs are observed. RCP is found to play an important role, cracks present near the end-support cause an abrupt drop in RNFs. Further, multiple cracks are observed to enhance the nonlinearity of LHCB strength. Introduction of the first to third crack in an intact LHCB results drop of RNFs by 8%, 10%, and 11.5% correspondingly. Also, it is demonstrated that the RNF varies because of the lamina-orientation, and filler addition. For 0° lamina-orientation the RNF is maximum. Similarly, it is studied that the addition of graphene reduces weight and increases the stiffness of LHCB in contrast to the addition of flyash. Additionally, the response of LHCB to moving mass is accessed by appropriately modifying the numerical programs, and it is noted that the successive introduction of the first to ninth crack results in an approximately 40% to 120% increase in the dynamic-amplitude-ratio.