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나영수(Na, Young-Soo),노삼영(Noh, Sam-Young) 대한건축학회 2020 대한건축학회 학술발표대회 논문집 Vol.40 No.2
For the Analysis of the progressive collapse resistance performance of a structure mode It is recommended to use 3-D structure model, considering the 3-D effect of the slab, the continuity of the adjacent span, and the redistribution of stress through the alternated path of the upper level. Although 3-D structure is applied with 1-D members and joints, 2-D slab models to reduce analysis time and amount of data, the large size of the target structure still requires a lot of modeling time and analysis time. Thus, in this study, the sub-assemblage structure modeling method was presented in three levels considering the number of impacted span by the sudden column removal and the bending rigidity of the columns to located out of the sub assemblage structure model.
전기화학 계면반응에 기초한 DSA 전극을 사용한 고성능 폐수처리 시스템
나영수 ( Young Soo Na ),이만성 ( Man Sung Lee ),김경호 ( Kyoungho Kim ) 한국접착및계면학회 2018 접착 및 계면 Vol.19 No.3
도시의 산업화와 인구의 빠른 증가로 인해, 지구상에서 여전히 7억 8천만명이 물자원 사용에 어려움을 격고 있으며, 이에 따라 깨끗하고 저렴한 물자원 확보 방안에 대한 관심이 집중되고 있다. 그러나, 현존하는 폐수처리 시스템은 낮은 공정효율, 높은 운영비용, 그리고 넓은 부지 요구 등의 다양한 이슈에 직면하여 있는 실정이다. 따라서, 저렴하고 효율적인 폐수 처리 시스템의 개발이 시급히 요구된다. 이러한 노력의 일환으로 rutile type RuO<sub>2</sub>를 기반으로 한 DSA전극을 이용한 전기 화학적 방법에 기초한 폐수 처리 시스템을 제안하였고, 이를 성공적으로 시연하였다. 우리의 폐수 처리 시스템은 생활폐수의 경우, 생화학적 산소 요구량 (BOD), 화학적 산소 요구량 (COD) 및 총 유기탄소 (TOC) 제거 효율이 52.0 %, 77.8 % 및 65.6 % 로 우수한 특성을 보였다. 또한 축산 폐수의 경우, BOD, COD, 총 질소(TN), 총 인 (TP)의 제거 효율이 각각 92.9 %, 75.6 %, 35.1 %, 100 %로 획기적인 감축 효과를 거두었습니다. 이 장치의 탁월한 제거 효율과 작은 크기를 고려할 때, rutile RuO2로 코팅된 DSA를 사용한 전기화학적 폐수 처리는 생활 및 축산 폐수의 처리를 위한 유망한 방안이 될 수 있음을 제안하고자 합니다. With the rapidly growing of the population and industrization of cities, the clean and affordable water resources have gained immense interest because of remaining about 780 million people still lack access to it. However, present wastewater treatment systems have been faced with various issues, such as low processing efficiency, high operational costs and the requirement of a large area for manufacturing. It is therefore urgently required to develop an inexpensive and efficient wastewater treatment system. As the one of these efforts, we suggested and successfully demonstrated the wastewater treatment system using and electrochemical method via a dimensionally stable anode (DSA) based on rutile type RuO<sub>2</sub>. Our system achieved biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) removal efficiently at the respective rates of 52.0%, 77.8%, and 65.6% from household wastewater. In addition, we were able to remove BOD, COD, total nitrogen (TN), and total phosphorus (TP) from animal husbandry wastewater at rates of 92.9%, 75.6%, 35.1%, and 100%, respectively, thereby achieving dramatic reductions. Considering the excellent removal efficiency and the small size of this device, electrochemical wastewater treatment using a DSA coated in rutile RuO2 presents a promising option for the treatment of both household and animal husbandry wastewater.
나영수(Na, Young-Soo),노삼영(Noh, Sam-Young),이업(Li, Ye) 대한건축학회 2021 대한건축학회논문집 Vol.37 No.9
For the analysis of the progressive collapse resistance performance of a structure, it is recommended to use a 3-D structure model that considers the 3-D effect of the slab, the continuity of the adjacent spans, and the redistribution of stress through the alternated path of the upper stories. Although a structure is modeled with reduced modeling concepts, the large size of the target structure still requires a lot of time on modeling and analysis. In this study, the sub-assemblage structure modeling concept was presented. The area of the sub-assemblage structure was determined by the analysis of the number of affected spans using the stress variation in the members before and after the sudden column removal in the entire structure model. The modeling concept was suggested in three levels according to the degree of the modelled detail of members located in the outer area of the sub-assemblage structure. They are evaluated by comparing the load-displacement relationship, girder stresses and plastic hinging locations with those resulted by the simulation of entire structure model.
대류 유동조건에서 Al₂O₃ 나노유체의 유효 열전도율과 비열
나영수(Young Su Na),오동욱(Dong-Wook Oh),이준식(Joon Sik Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
This study aims to figure out the effect of convective flow on the conventional specific heat and the formally reported effective thermal conductivity of Al2O3 nanofluid which has been obtained at a stationary state. The experimental conditions are fully developed laminar flow at a constant heat flux boundary condition through a circular tube. As a result, the Nusselt number of nanofluid is observed lower than the analytic value of 4.36. It implies that the specific heat of nanofluid under convective flow decreases through the increment of the volume flow rate.
대류 유동조건에서 알루미나-물 나노유체의 유효 열확산율에 대한 유동 영향
나영수(Young-Su Na),이준식(Joon Sik Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
This study aims to figure out the effect of convective flow on the effective thermal diffusivity of Al₂O₃-DI water nanofluids. The conventional thermal diffusivity is defined by the thermal conductivity and the heal capacity under a static state. In this study, the thermal diffusivity under convective flow is defined in terms of the temperatures of fluids and heated wall when the velocity and the temperature profiles are assumed fully developed in a circular tube under laminar flow and constant heat flux. The significant distinction between the effective thermal diffusivity under convective flow and that under a static state is observed due to flow dependence at the same thermal condition. The effective thermal diffusivity under convective flow shows stronger dependence on the velocity than the temperature.
알루미나 나노유체의 유효 열확산율에 대한 대류 유동조건의 영향
나영수(Young Su Na),이준식(Joon Sik Lee),김경덕(Kenneth D. Kihm) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
This study compares the effective thermal diffusivities of water-based Alumina nanofluid under convective flow condition with those under static condition. In general, the thermal diffusivity is defined by the thermal conductivity and heat capacity under static condition. In this study, the thermal diffusivities under fully developed laminar flow in a circular tube were calculated by measuring temperatures without using the thermal properties. In contrast with the strong temperature dependence on the effective thermal diffusivities under static condition, those under convective flow condition increased with decreasing mean fluid temperature induced by increasing volume flow rate at constant heat flux. This opposite trend of the temperature dependence on the effective thermal diffusivities under convective flow condition was explained by particle migration due to stronger thermophoresis diffusivity than Brownian diffusivity.
대류유동조건에서 나노입자를 포함한 콜로이드의 유효열전도율
나영수(Young Su Na) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
The effective thermal conductivity of a convective flowing colloidal system, called as the dynamic thermal conductivity, was measured, and it was compared with the effective thermal conductivity of a stationary colloid, called as the static thermal conductivity. Nano-sized alumina particles suspended in water are under the fully developed laminar tube flow with uniformly heating and cooling condition. In the heating condition, the dynamic thermal conductivity is lower than the static thermal conductivity, and it increases with the increment of the Reynolds number. In opposition to the heating condition, the dynamic thermal conductivity in the cooling condition is higher than the static thermal conductivity, and it decreases with the increment of the Reynolds number. This contrary trend of the dynamic thermal conductivity between heating and cooling conditions can be explained by thermophoresis that determines the behavior of nano-sized particles. The concentration of nano-sized particles suspended in water will be coarse or dense locally near the heating or cooling surface, respectively, and the thermophoretic velocity of dispersed particles depends on the temperature regarding the Reynolds number.