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유한요소법을 이용한 3차원 염해 침투 예측 모델의 개발
최원,김한중,Choi, Won,Kim, Hanjoong 한국농공학회 2015 한국농공학회논문집 Vol.57 No.5
Most of agricultural structures located in seashore could not avoid rapid deterioration of concrete because chloride-ion and $CO_2$ gradually penetrate into concrete. However, since most of models can be able to describe the phenomenon of penetration by using one or two dimensional models based on finite difference method (FDM), those modes can not simulate the real geometry and it takes a lot of computational time to complete even the calculation. To overcome those weaknesses, three dimensional numerical model considering time dependent variables such as surface concentration of chloride and diffusion coefficient of domain based on finite element method (FEM) was suggested. This model also included the neutralization occurred by the penetration of $CO_2$. Because the model used various sizes of tetrahedral mesh instead of equivalent rectangular mesh, it reduced the computational time to compare with FDM. As this model is based on FEM, it will be easily extended to execute multi-physics simulation including water evaporation and temperature change of concrete.
UV-VIS 초분광 위성센서 모의복사휘도를 활용한 다양한 관측환경에서의 에어로솔 유효고도에 대한 O4 대기질량인자 민감도 조사
최원이 ( Wonei Choi ),이한림 ( Hanlim Lee ),최철웅 ( Chuluong Choi ),이양원 ( Yangwon Lee ),노영민 ( Youngmin Noh ) 대한원격탐사학회 2020 大韓遠隔探査學會誌 Vol.36 No.2
본 연구에서는 복사전달모델을 사용하여 다양한 변수환경(파장 (340 nm, 477 nm), 에어로솔 종류(스모크, 황사, 황산염), AOD (aerosol optical depth), 지표면 반사도, 관측기하)에 따라 에어로솔 유효 고도(aerosol peak height; APH)에 대한 O<sub>4</sub> 대기질량인자(air mass factor; AMF)의 민감도를 조사하였다. 전반적으로, 477 nm의 O<sub>4</sub> AMF 가 340 nm 보다 APH에 대한 민감도가 크고 안정적으로 산출 가능한 것으로 확인하였다. AOD가 높을 때 APH에 대한 O<sub>4</sub> AMF의 민감도가 커지는 것을 확인하였다. 477 nm에서는 340 nm 보다 지표면 반사도의 영향이 큰 것으로 나타났다. 태양천정각 증가에 따라 340 nm에서의 O<sub>4</sub> AMF가 감소하는 추세를 발견하였으며, 이러한 경향은 태양천정각 40°인 환경에서 높은 Rayleigh 및 Mie 산란에 의한 장벽효과로 인해 O<sub>4</sub> 흡수가 발생하는 광경로 길이가 줄어들기 때문인 것으로 사료된다. 477 nm에서는 태양천정각이 증가함에 따라 Rayleigh 및 Mie 산란에 의한 다중산란이 일부 발생하여 O<sub>4</sub> AMF가 비선형함수 형태로 증가하는 경향을 보였다. 마지막으로, AOD의 불확실성이 APH 산출오차에 미치는 영향을 조사하였다. 황산염 타입에 대한 APH 산출 시, AOD의 불확실성으로 인한APH 산출오차가 다른 에어로솔 타입보다 크게 나타났으며, 황사의 경우 AOD 불확실성에 대한 APH 산출오차에 대한 영향이 미미하게 나타났다. 이러한 결과는 각 에어로솔 타입의 흡수 산란 특성이 다양하기 때문에, 에어로솔 타입이 APH 산출 오차에 영향을 미칠 수 있음을 의미한다. In this present study, the sensitivity of O<sub>4</sub> Air Mass Factor (AMF) to Aerosol Peak Height (APH) has been investigated using radiative transfer model according to various parameters (wavelength (340 nm and 477 nm), aerosol type (smoke, dust, sulfate), aerosol optical depth (AOD), surface reflectance, solar zenith angle, and viewing zenith angle). In general, it was found that O<sub>4</sub> AMF at 477 nm is more sensitive to APH than that at 340 nm and is stably retrieved with low spectral fitting error in Differential Optical Absorption Spectroscopy (DOAS) analysis. In high AOD condition, sensitivity of O<sub>4</sub> AMF on APH tends to increase. O<sub>4</sub> AMF at 340 nm decreased with increasing solar zenith angle. This dependency is thought to be induced by the decrease in length of the light path where O4 absorption occurs due to the shielding effect caused by Rayleigh and Mie scattering at high solar zenith angles above 40°. At 477 nm, as the solar zenith angle increased, multiple scattering caused by Rayleigh and Mie scattering partly leads to the increase of O<sub>4</sub> AMF in nonlinear function. Based on synthetic radiance, APHs have been retrieved using O<sub>4</sub> AMF. Additionally, the effect of AOD uncertainty on APH retrieval error has been investigated. Among three aerosol types, APH retrieval for sulfate type is found to have the largest APH retrieval error due to uncertainty of AOD. In the case of dust aerosol, it was found that the influence of AOD uncertainty is negligible. It indicates that aerosol types affect APH retrieval error since absorption scattering characteristics of each aerosol type are various.
난치성 봄철각결막염에서 유두절제술과 상안검판 트리암시놀론 주사의 동시 치료 효과
최원,임성규,윤경철,Won Choi,Seong-Gyu Lim,Kyung Chul Yoon 대한안과학회 2010 대한안과학회지 Vol.51 No.4
Purpose: To evaluate the therapeutic effect of the combined treatment of excision of the papillae and a supratarsal injection of triamcinolone on refractory vernal keratoconjunctivitis (VKC). Methods: Twenty-three eyes of 14 patients with refractory vernal keratoconjunctivitis were included. Patients were treated with the combined excision of papillae and supratarsal injection of triamcinolone. Best corrected visual acuity (BCVA), intraocular pressure, symptoms of itching, tearing, discomfort, secretion and epiphora, and signs including limbal hypertrophy, hyperemia, papilla size, keratitis, corneal neovascularization and blepharitis were evaluated before and two weeks, four weeks, and eight weeks after treatment. The CCL11 level in the tears of each eye were analyzed before and two weeks after treatment. Results: The mean scores of subjective symptoms and objective signs as well as BCVA were significantly improved two weeks after treatment. CCL11 levels in the tears were 389.5±474.9 pg/ml before treatment and were undetectable two weeks after treatment. Improvement of symptom and sign parameters was maintained up to eight weeks after treatment. However, seven eyes (30.4%) recurred within two weeks after treatment. Conclusions: Combined excision of the papillae and a supratarsal injection of triamcinolone may be effective in the treatment of refractory VKC. J Korean Ophthalmol Soc 2010;51(4):492-497