Proposed approach for determination of tributary areas for scattered pressure taps

Aly, Aly Mousaad Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.16 No.6

In wind load calculations based on pressure measurements, the concept of 'tributary area' is usually used. The literature has less guidance for a systematic computational methodology for calculating tributary areas, in general, and for scattered pressure taps, in particular. To the best of the author's knowledge, there is no generic mathematical equation that helps calculate the tributary areas for irregular pressure taps. Traditionally, the drawing of tributary boundaries for scattered and intensively distributed taps may not be feasible (a time and resource consuming task). To alleviate this problem, this paper presents a proposed numerical approach for tributary area calculations on rectangular surfaces. The approach makes use of the available coordinates of the pressure taps and the dimensions of the surface. The proposed technique is illustrated by two application examples: first, quasi-regularly distributed pressure taps, and second, taps that have scattered distribution on a rectangular surface. The accuracy and the efficacy of the approach are assessed, and a comparison with a traditional method is presented.

Proposed approach for determination of tributary areas for scattered pressure taps

Aly Mousaad ALY 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.16 No.6

In wind load calculations based on pressure measurements, the concept of ‘tributary area’ is usually used. The literature has less guidance for a systematic computational methodology for calculating tributary areas, in general, and for scattered pressure taps, in particular. To the best of the author’s knowledge, there is no generic mathematical equation that helps calculate the tributary areas for irregular pressure taps. Traditionally, the drawing of tributary boundaries for scattered and intensively distributed taps may not be feasible (a time and resource consuming task). To alleviate this problem, this paper presents a proposed numerical approach for tributary area calculations on rectangular surfaces. The approach makes use of the available coordinates of the pressure taps and the dimensions of the surface. The proposed technique is illustrated by two application examples: first, quasi-regularly distributed pressure taps, and second, taps that have scattered distribution on a rectangular surface. The accuracy and the efficacy of the approach are assessed, and a comparison with a traditional method is presented.

낙동강 지류·지천 모니터링 결과를 이용한 수질환경 평가

임태효 ( Tae Hyo Im ),손영규 ( Younggyu Son ) 한국환경과학회 2016 한국환경과학회지 Vol.25 No.12

Water quality in Nakdong river was analyzed using 699 monitoring data sets including flow rates and water quality concentrations collected at 195 tributary monitoring stations (the priority management areas: 35 stations, the non-priority management areas: 160 stations) in 2015. The highest average concentrations of all data for BOD, COD, T-N, T-P, SS, and TOC were 30~600 times higher than the lowest concentrations while the highest average loading rates were 800,000~2,700,000 times higher than the lowest loading rates. Because of the very large differences in the concentrations and loading rates, the variation of the concentrations and loading rates in a priority management monitoring station for BOD, T-P, and TOC was analyzed using the coefficient of variation, the ratio of the standard deviation value to the mean value. For BOD, T-P, and TOC, the coefficients of variation for concentration were mostly less than 100%, whereas the coefficients of variation for loading rate ranged from 31.1% to 232.2%. The very big difference in the loading rates was due to the large variation in flow rates. As a result of this, the estimation of water quality at each monitoring station using the average values of the concentrations and loading rates might be not rational in terms of their representativeness. In this study, new water quality analysis methods using all collected monitoring data were suggested and applied according to the water quality standard in medium-sized management areas.

고려시대 차산지와 공납차(貢納茶) 생산에 관한 一考

박영식(Youngsik Park) 한국차학회 2017 한국차학회지 Vol.23 No.1

In Korea s history, the tea culture flourished the most during the Goryeo dynasty. Tea was used a great deal, but few records of it remain. With regard to the tea which was heavily consumed during this flourishing Goryeo tea culture, this study sought to reveal the tea production areas and the types of tea produced. Goryeo imposed taxes according to the Gun and Hyun (counties and provinces), thereby creating the taxation ledgers known as Gongan, and required the tea production to be shared by villages within such administrative units. In addition, Goryeo implemented the Bugokjedo (a lower administrative unit classification system) within such Gun and Hyeon, where there were the Daso (tea specialist production villages). Based on the early Joseon Jiriji Geographical Records, there were 35 tea production areas during the Goryeo era, four of which had 17 Daso, whereas most of the other records did not mention the presence of Daso. Also, tributary tea was produced according to the state system by mobilizing villages workers. Based on the tea production view of Hwagae, as described in Yi Gyu-bo s poem in the mid-Goryeo period, it is presumed that Goryeo produced tea not only in Daso, but also in Bugok areas by mobilizing workers. The tea produced was transported by mobilized workers to the royal household or to the various central government offices. This study estimated the Goryeo tea production areas and provides an outline of the system of production and transportation of tributary tea and its supply to the government. In addition, we reexamined the prejudice against the tea produced in the Daso during the Goryeo period.

통⋅근학으로 본 충청지역의 도시세력권

정환영 한국사진지리학회 2019 한국사진지리학회지 Vol.29 No.3

본 연구에서는 2000년과 2015년 인구센서스 통근⋅통학 마이크로 데이터를 활용하여 도시 위계에 따른 충청지역의 도시세력권을 분석하고자 하였다. 2000년과 2015년 충청지역의 도시시스템을 분석한 결과 전체적인 틀은변함이 없었으나, 대전광역시보다 청주시가 상대적으로 확장되는 경향을 보이고 있고, 천안, 아산시 등 충남 서북부도시의 위상이 강화되고 있음을 알 수 있다. 외부통근율의 변화를 살펴보면, 대전, 청주, 천안 등의 대도시와 이격되어 있는 지역에서 외부통근율이 낮게 나타나고 있다. 통⋅근학에 의한 도시세력권의 변화를 분석한 결과, 대전광역시는 2000년에는 반경 30km 내외였던 것이 2015년에는 반경 50km 내외로, 청주시는 반경 20-30km에서 반경40km 정도 범위까지, 천안시는 반경 15km에서 반경 35km 정도 범위까지 확대되었다. 세종시의 인구는 급격하게늘고 있으나, 도시계층의 형성은 아직 미약한 단계라고 할 수 있다. 향후 세종특별자치시의 도시기능 확충과 도시위상의 변화에 따라 대전-세종-청주로 이어지는 삼각 거대도시권의 형성이 예상된다.

지류론과 암주 강도의 추정에 의한 주방식 지하구조의 무지보 암주 설계

장수호(Soo-Ho Chang),이철호(Chulho Lee),최순욱(Soon-Wook Choi),허진석(Jinsuk Hur),황제돈(Jedon Hwang) 한국암반공학회 2014 터널과지하공간 Vol.24 No.5

무지보 암주에 의해 채굴적의 안정성을 확보하는 주방식 채광법은 전 세계적으로 가장 일반적이며 널리 활용되고 있는 지하 채광법이다. 경제적이고 운용 중에 확장이 가능한 주방식 채광법을 지하공간 건설에 적용하기 위한 기초 연구로서, 본 연구에서는 주방식 지하구조에서 가장 중요한 무지보 암주의 설계방법을 고찰하고 주요 설계변수들에 대한 총 125개 조건의 변수해석을 실시하였다. 이상의 연구결과, 암주의 폭과 암주의 안전율은 매우 뚜렷한 선형관계를 보이며, 암석의 압축강도가 동일할 경우에는 공간 폭과 암주 폭의 비율이 증가할수록 무지보 암주의 안전율이 음지수 함수 형태로 감소하는 것으로 나타났다. 또한 변수해석 결과들을 바탕으로, 암석의 압축강도와 설계 안전율에 따라 무지보 암주의 설계 형상변수를 쉽게 추정할 수 있는 도표를 제시하였다. Room-and-pillar mining method is one of the most popular underground mining method in the world. If the room-and-pillar mining method is able to be adopted in civil works, it would be highly probable to reduce underground construction costs and to expand a underground structure in use. Therefore, this study aims to analyze the design procedure of unsupported rock pillars which are indispensable to ensure the stability of a room-and-pillar underground structure. Parametric studies on their key design parameters are also carried out for 125 different kinds of design conditions. From the study, the width of a rock pillar is found to show a linear relationship with its corresponding safety factor. The safety factor of a unsupported rock pillar decreased drastically like a negative exponential function as the ratio of room width to pillar width increases in the same rock strength condition. Based on the parametric studies, a design chart to simply evaluate the geometric design parameters of a unsupported rock pillar satisfying a design safety factor is also proposed in this study.

관리 우선순위 선정을 위한 낙동강 지류·지천 지점의 수질 오염 특성 분석

임태효(Tae Hyo Im),나승민(Seungmin Na),신상민(Sangmin Shin),손영규(Younggyu Son) 대한환경공학회 2016 대한환경공학회지 Vol.38 No.10

낙동강 195개 지류․지천 지점에서 2015년 수집된 699회의 유량 및 BOD/COD/T-N/T-P/SS/TOC 농도 등의 수질 자료를 이용하여 중점관리지점 선정 연구를 수행하였다. 각 모니터링 지점에서 BOD, T-P, TOC 농도 및 오염부하량에 대한 변동계수가 매우 크게 확인되어 1년 평균 자료를 이용한 중점관리지점 선정이 경우에 따라 불합리할 수 있을 것으로 지적되었다. 이러한 이유로 본 연구에서는 각 모니터링 자료를 평균화하지 않고 독립적으로 이용할 수 있는 두 가지 방법을 제시하였다. 첫 번째 방법으로 각 모니터링 시점별로 수집된 BOD, T-P, TOC 농도를 낙동강 중권역별 목표수질과 비교하여 목표수질을 초과하는 횟수를 각 지점별로 산정하였다. 두 번째로 BOD, T-P, TOC 항목에 대한 오염부하량을 각 모니터링 시점별 및 지점별로 산정하여 % 순위를 산정하는 방법을 적용하였다. 이상의 방법을 통해 결정된 중점관리지점을 서로 비교하였으며, 이를 통해 낙동강 유역의 수질의 전반적 특성을 분석하였다. Water quality data including flow rates and BOD/COD/T-N/T-P/SS/TOC concentrations in Nakdong river tributaries were analyzed to determine priority management areas using 699 data sets from 195 locations in 2015. It was pointed out that the coefficients of variation, the ratio of the standard deviation to the mean, for the concentrations and loading rates of BOD, T-P, and TOC in each monitoring location were so large that average values of water quality monitoring data might be not appropriate to determine the priority management areas among all 195 monitoring stations in Nakdoing river. Therefore we suggested two evaluation methods using each water quality data independently. In the first method the excess numbers of the BOD, T-P, and TOC concentrations comparing to the water quality standards in the medium-sized management areas in Nakdong river was evaluated for each monitoring station. In the second method the percentile ranks of the loading rates of the BOD, T-P, and TOC were obtained for each monitoring data. The two groups of the priority management areas determined by each method were compared and the water quality characteristics in Nakdoing river were investigated.

편지붕형 지붕면에 작용하는 풍압계수 특성분석

유기표,조슬기,김영문 한국공간구조학회 2009 한국공간구조학회지 Vol.9 No.4

Damage on low‐rise buildings caused by typhoons and storms is increasing every year. Thus, this study examined the distribution of wind pressure coefficient at each position according to the height of monosloped roof, and measured wind pressure coefficient according to tributary area and compared it with the current wind load standard. We analyzed six areas in order to analyze characteristics at each position of a half‐span roof, and found that the wind pressure coefficient was around 25% higher at the high corner (HC) than at the low corner (LC). The distribution pattern of peak pressure coefficient at each position was the same as the AIK load standard, but in the results of our experiment, wind pressure was around 40% lower than the load standard at HC and around 37% higher than the load standard at LC. 요 약 매년 발생하는 태풍이나 강풍에 의해 저층건물의 피해가 증가하고 있는 실정이다. 본 논문에서는 편지붕에 대한 높이변화에 따른 위치별 풍압계수 분포와 하중부담면적 변화에 따른 풍압계수의 평가를 통하여 현재 풍하중기준과 비교해보고자 한다. 편지붕의 위치별 특징을 알아보기 위해 6개 영역으로 나누어서 분석을 하였으며 지붕에서 각도가 높은(high) 모서리(HC)가 낮은 (low) 모서리(LC)보다 25%정도 크게 나타나고 있었다. AIK 하중기준과 위치별 피크 외압계수 분포가 동일한 양상으로 나타나고 있지만 실험결과 HC영역의 경우 하중기준보다 40%정도 작은 값을, LC영역의 경우 하중기준보다 37%정도 큰 값을 나타내고 있었다.

Use of vibration characteristics to predict the axial deformation of columns

H.N. Praveen Moragaspitiya,David P. Thambiratnam,Nimal J. Perera,Tommy H.T. Chan 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.1

Vibration characteristics of columns are influenced by their axial loads. Numerous methods have been developed to quantify axial load and deformation in individual columns based on their natural frequencies. However, these methods cannot be applied to columns in a structural framing system as the natural frequency is a global parameter of the entire framing system. This paper presents an innovative method to quantify axial deformations of columns in a structural framing system using its vibration characteristics, incorporating the influence of load tributary areas, boundary conditions and load migration among the columns.

Use of vibration characteristics to predict the axial deformation of columns

Moragaspitiya, H.N. Praveen,Thambiratnam, David P.,Perera, Nimal J.,Chan, Tommy H.T. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.1

Vibration characteristics of columns are influenced by their axial loads. Numerous methods have been developed to quantify axial load and deformation in individual columns based on their natural frequencies. However, these methods cannot be applied to columns in a structural framing system as the natural frequency is a global parameter of the entire framing system. This paper presents an innovative method to quantify axial deformations of columns in a structural framing system using its vibration characteristics, incorporating the influence of load tributary areas, boundary conditions and load migration among the columns.