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대전시 공공하수처리시설 유입수 수질자료의 통계적 특성 및 추계학적 모의
박기정 ( Gi Jung Park ),정민재 ( Min Jae Jung ),이한샘 ( Han Saem Lee ),김덕우 ( Deok Woo Kim ),윤재영 ( Jae Yong Yoon ),백경록 ( Kyung Rock Paik ) 한국물환경학회 2012 한국물환경학회지 Vol.28 No.1
In this study, we analyze statistical characteristics of influent water quality in Daejeon waste water treatment plant and apply a stochastic model for data generation. In the analysis, the influent water quality data from year 2003 to 2008, except for year 2006, are used. Among water quality variables, we find strong correlations between BOD and T-N; T-N and T-P; BOD and T-P; CODMn and T-P; and BOD and CODMn. We also find that different water quality variables follow different theoretical probability distribution functions, which also depends on whether the seasonal cycle is removed. Finally, we generate the influent water quality data using the multi-season 1st Markov model (Thomas-Fiering model). With model parameters calibrated for the period 2003~2005, the generated data for 2007~2008 are well compared with observed data showing good agreement in general. BOD and T-N are underestimated by the stochastic model. This is mainly due to the statistical difference in observed data itself between two periods of 2003~2005 and 2007~2008. Therefore, we expect the stochastic model can be applied with more confidence in the case that the data follows stationary pattern.
김경록(Kyoung-rock Kim),팜반트룽(Pham van Trung),윤근위(Guen-wui Yoon),이명기(Myeong-gi Lee),김경홍(Kyoung-hong Kim),안형준(Hyeong-joon Ahn),이원(Won Yi) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
본 논문은 유연보를 이용한 준영강성 제진기의 제어 모델에 관한 것이다. 유연보 이용 준영강성 제진기는 유연보에 가해지는 압축력에 의해 유발되는 음강성이 수직방향 스프링의 양강성과의 합이 0부근이 되는 준영강성 원리를 이용한다. 먼저 준영강성제진기의 핵심요소인 유연보의 무차원 엄밀해를 유도하고 테일러 전개로 간략하한 후 유한요소해석을 통해 검증하였다. 간략화한 유연보 모델로 유연보 이용 준영강성 제진기의 동역학 모델을 구성하고 비선형 진동특성을 확인하였다. 구성한 제진기 시스템 모델을 통해 설계 변수에 따른 제진기의 동특성 민감도를 분석하고, 압축력 이용 능동 제진을 위한 제어 모델을 유도하였다. 제진기의 동특성이나 능동 제어에 유연보 형상이 큰 영향이 있음을 확인하였다. This paper presents a control model of a quasi zero stiffness isolator using flexures. The isolator has the QZS characteristic acquired by combination of a negative stiffness of the flexure with compressive force and a positive stiffness of a vertical spring. First, non-dimensional exact model of the flexure or a key element of the QZS isolator is derived and the exact model of the flexure is simplified into an approximate model using Taylor series expansion, which is verrified with FE analysis. Based on the approximate model of flexure, a nonlinear dynamic model of the QZS isolator is constructed and its non-linear vibration characteristics are verified with simulations. Sensitivity analysis of dynamic characteristic of the QZS isolator according to design parameters is performed and an engineering model of the isolator for active control using compression force is derived. The shape of flexure has significant effect on the dynamics characteristic and control of the isolator.
김용식(Kim Yong-Sik),강기환(Kang Gi-Hwan),심상용(Sim Sang-Yong),이후락(Lee Hoo-Rock),이진섭(Lee Jin-Seob),홍진기(Hong Jin-Ki) 한국태양에너지학회 2009 한국태양에너지학회 논문집 Vol.29 No.1
This paper aims at enhancing the electric production efficiency of photovoltaic(PV) system. The electrical power of PV system is proportional to light intensity on a PV module surface. In this paper, we apply two types of systems to enhance power generation efficiency. First of all, concentring sunlight using specular surface and one-axis tracking system which traces the sun with vertical direction are applied in this project. From this, we analyze the fixed type method and power generation efficiency.
Processing of continuous poly(amide-imide) nanofibers by electrospinning
Lee, Seung Hwan,Kim, Seong Yun,Youn, Jae Ryoun,Seong, Dong Gi,Jee, Seung Yong,Choi, Jin Il,Lee, Jae Rock John Wiley Sons, Ltd. 2010 Polymer international Vol.59 No.2
<P>Continuous poly(amide-imide) nanofibers were fabricated using a novel electrospinning method with rotating and re-collecting cylindrical collectors. The nanofilaments were modified using various post-treatments, i.e. glycerol treatment and thermal imidization under tension, for possible application as high-performance reinforcements. Morphological and mechanical properties of continuous poly(amide-imide) nanofibers prepared by the electrospinning process and various post-treatments were measured. Severe adhesion between individual nanofibers within fiber bundles was inhibited through surface treatment of the electrospun nanofiber bundles by spraying with glycerol. The morphological and mechanical properties of the continuous poly(amide-imide) nanofibers and thermal stability were improved using thermal imidization at high temperature under tension. The morphological and mechanical properties of the continuous electrospun nanofibers were improved significantly by post-treatments after electrospinning because uniform and complete thermal imidization occurred through the core region of the nanofibers. Copyright © 2009 Society of Chemical Industry</P> <B>Graphic Abstract</B> <P>Continuous poly(amide-imide) nanofibers prepared by using dual cylindrical collectors were post-treated with glycerol spraying and thermal imidization under tension after electrospinning. <img src='wiley_img/09598103-2010-59-2-PI2710-gra001.gif' alt='wiley_img/09598103-2010-59-2-PI2710-gra001'> </P>