전단파괴가 발생한 기둥의 이력거동 예측을 위한 매개변수 결정방법 제안

이창석,한상환,고길보 한국지진공학회 2017 한국지진공학회논문집 Vol.21 No.1

Columns in existing reinforced concrete structures that are designed and constructed without considering seismic loads generally exhibit widely spaced transverse reinforcements without using seismic hooks. Due to the insufficient reinforcement details in columns compared to the reinforcement requirements specified in modern seismic codes, brittle shear failure is likely to occur. This may lead to sudden collapse of entire structure during earthquakes. Adequate retrofit strategy is required for these columns to avoid such catastrophic event. In order to do so, behavior of columns in existing reinforced concrete structures should be accurately predicted through computational analysis. In this study, an analytical model is proposed for accurately simulating the cyclic behavior of shear critical columns. The parameters for backbone, as well as pinching and cyclic deterioration in strength and stiffness are calibrated using test data of column specimens failed by shear.

An analysis on Landscape Structure and Biodiversity of the Bokha Stream as a Model to Restore the Degraded Urban Stream

이창석,문정석,우효섭,안홍규,조강현,배양섭,변봉규 한국생태학회 2006 Journal of Ecology and Environment Vol.29 No.2

Landscape structure, habitat types, vegetation structure and biodiversity in the Bokha streamchosen as a reference stream were investigated to get ecological information necessary for restoration of urban stream degraded by excesive artificial interference. Landscape structure showed a slight change betwen before and after flooding. Habitat types of nine sorts were identified based on ecological information obtained from field survey such as micro-topography, hydrological characteristics, disturbance regime, and so on. Each habitat holds specific organisms to each site. Consequently, the number of plant comunities, and species of benthos and fish increased as the kinds of habitat type increase. Ordination of habitat types based on vegetation, benthos, and fish data reorganized them into three groups of pool types of two kinds depending on whether they are connected to the water course or not and riffle one. Vegetation showed different stratification and species composition depending on topographical position in relation to disturbance cycle. Based on the results from this study, relationship between environmental heterogeneity and biodiversity was discussed and a restoration plan was suggested in a viewpoint of vegetation.

하천계획, 평가 및 적응관리 기술개발

이창석,Lee, Chang-Seok 한국수자원학회 2008 물과 미래(한국수자원학회지) Vol.41 No.9

Changes of Landscape Structure for the Recent 20 Years in the Wangsuk Stream Basin of the Central Korea

이창석,조용찬,신현철,이선미 한국생태학회 2006 Journal of Ecology and Environment Vol.29 No.4

Landscape changes for 20 years betwen 1981 and 2001 in the Wangsuk stream basin locatedon the central Korea were investigated on the basis of physiognomic vegetation map made from the aerialphotograph interpretation and field check. Changes of landscape structure were noticeable in agricultural fieldinto the institutional agriculture dominated landscape change, although urbanization also contributed to suchchange. The former change due to change of food production structure originated from socio-economicdevelopment during this period and the latter to the overpopulation of Seoul. As energy sources for heating andcooking, fertilizer, and fodder for livestock transform from plant materials to fossil fuel, manufactured one, andgrain, succession of forest escaped from direct human disturbance dominated change of landscape structure inforested land. Differently from the positive landscape change in the upper area, change in the lower areathe Wangsuk stream basin would influence water quality of the stream. In order to realize sustainable land-useagainst such environmental degradation, systematic environmental management based on landscape cologicalperspective such as an eco-plan for creating riparian vegetation belt, which is under preparation by Ministryof Environment, was recommended.

Which Environmental Factors Caused Lammas Shoot Growth of Korean Red Pine?

이창석,송혜경,김혜수,이빛나라,피정훈,초용찬,설은실,오우석,박송애,이선미 한국생태학회 2007 Journal of Ecology and Environment Vol.30 No.1

Lammas growth, a rare phenomenon for Korean red pine (Pinus densiflora), occurred in 2006.Lamas shoots showed higher frequency and longer length in Seoul's hotter urban center than in urban boundary or suburban forest sites. Frequency and length showed a close correlation with urbanization density and vegetation cover expressed in NDVI. Air temperature in the late summer of 2006 was more than 1℃ higher than an average year. Of the predominant environmental signals thatmodulate bud flush, only temperature changed significantly during the year. Differences in temperature between the urban centers, urban boundaries and suburban forests correlated with varying land-use density. The rise in temperature likely spurred lamas consequences wil be clearer in the future. Considerate interest in the responses of ecological systems to the variable changes is required to prepare for unforeseeable crises. Monitoring of diverse ecological phenomena at Long Term Ecological Research sites could offer harbingers of change.

Computationally Effi cient and Accurate Simulation of Cyclic Behavior for Rectangular HSS Braces

이창석,성민수,한상환,지현우 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.4

During earthquakes, braces behave in complex manners because of the asymmetric response nature of their responses in tension and compression. Hollow structural sections (HSS) have been popularly used for braces due to their sectional effi - ciency in compression. The purpose of this study is to accurately simulate the cyclic behavior of rectangular HSS braces using a computationally effi cient numerical model. A conceptually effi cient and simple physical theory model is used as a basis model. To improve the accuracy of the model, cyclic beam growth and buckling load, as well as the incidences of local buckling and brace fracture are estimated using empirical equations obtained from regression analyses using test data on rectangular HSS braces. The accuracy of the proposed model is verifi ed by comparing actual and simulated cyclic curves of brace specimens with various slenderness and width-to-thickness ratios.

민영아파트 발코니의 이용실태 분석 및 확장에 관한 연구

이창석,장림종 대한건축학회 2007 대한건축학회논문집 Vol.23 No.8

The study aims to project a space planning for apartment balcony corresponding to the case studies and related analysis. It is based on the investigation of the current uses and their changes of apartment balcony and further examination of the problems and needs on the balcony from the point of users.Accordingly the research focuses on the actual usage conditions of the balconies of existing residents and the requiring degree of satisfaction and demands. The apartments for the case study have been selected based on move-in time, number of households, and management system of maintenance. The survey was carried out throughout the actual residents of the selected complex.As a result, the balcony extension survey and the already-extended balcony categorize an area of 84m2 as 'livingroom + front small bedroom + back small bedroom' an area of 114m2 as 'livingroom + front bedrooms' and propose a segregated balcony space and an extended balcony type for the current residents.

면역매개성 용혈성 빈혈 이환견에 발생한 혈전색전증 1례

이창석,전형규,조성남,이정연,이상은,송근호,이영원,최호정,박성준,조성환 한국임상수의학회 2007 한국임상수의학회지 Vol.24 No.2

A Study on the Correlation between Pad Property and Material Removal Rate in CMP

이창석,이호준,정문기,정해도 한국정밀공학회 2011 International Journal of Precision Engineering and Vol. No.

Chemical mechanical polishing (CMP) is a process with relative motion between pad and wafer while supplying slurry which abrasive particles are dispersed. This process consists of mechanical action by contact between pad and wafer and chemical action by the slurry chemicals. There are various factors affecting on material removal rate (MRR) in CMP. Especially, the pad plays a role of mechanical action by direct contact with wafer. Real contact area (RCA) between pad and wafer is an important factor when considering real contact pressure, friction and wear of pad asperities, which affects on the MRR and within wafer non-uniformity (WIWNU). This paper proposes a correlation between pad property and MRR in CMP process. The pad after conditioning had sharp asperities and changed to blunt ones as the polishing time became longer. This phenomenon was clarified by the roughness parameter of Rku. The high Rku pad just after conditioning made a high real pressure to the wafer, resulting in high MRR during CMP.

전력 분배기와 위상 변환기를 이용한 광대역 스트립라인 발룬에 관한 연구

이창석,박웅희,Lee, Chang-Seok,Park, Ung-Hee 한국정보통신학회 2008 한국정보통신학회논문지 Vol.12 No.7

본 논문에서는 광대역 특성을 갖는 스트립라인 발룬을 설계 및 제작하였다. 제안된 스트립라인 발룬은 광대역 특성을 위하여 월킨슨 전력 분배기와 두 개의 광대역 위상 변환기로 구성된다. 광대역 발룬의 설계 주파수 대역은 $500{\sim}1500\;MHz$ 대역이고, 발룬 특성은 반사계수($S_{11}$) -10 dB 이하, 결합 손실이 -0.05 dB 이하가 되게 하기 위하여 세기차 ${\pm}0.5\;dB$ 이내, 위상차 $180{\pm}10$도 이내를 목표로 하였다. 제작된 광대역 스트립라인 발룬은 폭 12 mm, 길이 220 mm, 두께 2.3 mm로 크기를 가졌으며, 제작된 발룬 특설은 $500{\sim}1500\;MHz$ 대역에서 반사계수($S_{11}$) -10 dB 이하 위상차 약 $180{\pm}8$도 이내, 세기차 약 ${\pm}0.7\;dB$ 이내, 신호 손실 약 -2 dB를 보였다. This paper presents an wideband stripline balun. And, the proposed balun is composed of one power divider and two phase converters on stripline substrate. The target characteristics of the proposed balun is the combination loss of below -0.05 dB, an amplitude imbalance of ${\pm}0.5\;dB$ and a phase imbalance of $180{\pm}10$ degrees, with the reflection coefficient(S11) of below -10 dB over frequencies ranging from 500 to 1500 MHz. The fabricated balun occupies the area of $12(W){\times}220(L){\times}2.3(T)\;mm3$. Experimental measurement shows that the fabricated balun has an amplitude imbalance of ${\pm}0.7\;dB$, a phase imbalance of $180{\pm}8$ degrees and an insertion loss of about -2 dB with the reflection coefficient(S11) of below -10 dB over frequencies ranging from 500 to 1,500 MHz.