• Steel and Composite Structures
• /
• 제26권6호
• /
• pp.793-808
• /
• 2018

In this study, the seismic performance of the connections between L-shaped columns composed of concrete-filled steel tubes (L-CFST columns) and H-beams used in high-rise steel frame structures was investigated. Seven full-scale specimens were tested under quasi-static cyclic loading. The variables studied in the tests included the joint type, the axial compression ratio, the presence of concrete, the width-to-thickness ratio and the internal extension length of the side plates. The hysteretic response, strength degradation, stiffness degradation, ductility, plastic rotation capacity, energy dissipation capacity and the strain distribution were evaluated at different load cycles. The test results indicated that both the corner and exterior joint specimens failed due to local buckling and crack within the beam flange adjacent to the end of the side plates. However, the failure modes of the interior joint specimens primarily included local buckling and crack at the end plates and curved corners of the beam flange. A design method was proposed for the flexural capacity of the end plate connection in the interior joint. Good agreement was observed between the theoretical and test results of both the yield and ultimate flexural capacity of the end plate connection.

• Steel and Composite Structures
• /
• 제32권3호
• /
• pp.337-346
• /
• 2019

The present paper tries to contribute fill the gap of application of the component method to tubular connections. For this purpose, one typical joint configuration in which just one component can be considered as active has been studied. These joints were selected as symmetrically loaded welded connections in which the beam width was the same as the column width. This focused the study on the component 'side walls of rectangular hollow sections (RHS) in tension/compression'. It should be one of the main components to be considered in welded unstiffened joints between I beams and RHS columns. Many experimental tests on double-sided I-beam-to-RHS-column joint with a width ratio 1 have been carried out by the authors and a finite element (FE) model was validated with their results. Then, some different analytical approaches for the component stiffness and strength have been assessed. Finally, the stiffness proposals have been compared with some FE simulations on I-beam-to-RHS-column joints. This work finally proposes the most adequate equations that were found for the stiffness and strength characterization of the component 'side walls of RHS in tension/compression' to be applied in a further unified global proposal for the application of the component method to RHS.

• 한국지진공학회논문집
• /
• 제17권3호
• /
• pp.97-105
• /
• 2013

In this paper, the a static experiment of on two reinforced concrete (RC) frame sub-assemblages was conducted to evaluate the seismic behaviors of existing RC frames that were not designed to support a seismic load. The specimens were a one span and actual-sized. One of them had two columns with the same stiffness, but the other had two columns with different stiffness values. As Regarding the test results, lots of many cracks occurred on the surfaces of the columns and beam-column joints for the two specimens, but the cover concrete splitting hardly occurred was minimal until the test ends. In the case of the specimen with the same stiffness offor the two columns, the flexural collapse of the left-side column occurred. However, in the case of the specimen with different stiffness values for of the two columns, the beam-column joint finally collapsed, even though the shear strength of the joint was designed to be strong enough to support the lateral collapse load. The nonlinear Nonlinear static analysis of the two specimens was also conducted using the uniaxial spring model, and the analytical results successfully simulated the nonlinear behaviour of the specimens in accordance with the test results.

• 동력기계공학회지
• /
• 제9권2호
• /
• pp.88-92
• /
• 2005

The experiment of thermal performance about closed-wet cooling tower was conducted in this study. A closed cooling tower is a device similar to a general cooling tower, but with cooling tower replaced by a heat exchanger. The test section for this experiment has the process that the cooling water flows from the top of the heat exchanger to the bottom side in the inner part of the tube, and spray water flows in the gravitational direction in the outer side. Air comes in direct contact with the spray water at the outer side of the tube while passing from the lower the upper part having a counterflow to the spray water. The heat transfer pipe used in this experiment is a bare-type tube having an outer diameter of 15.88mm. The heat exchanger is consisted of seven rows and fifteen columns. In this experiment, thermal performance of the cooling tower is derived from overall heat transfer coefficients between the process fluid and sprayed water and volumetric overall mass transfer coefficient between sprayed water and air.

• Applied Microscopy
• /
• 제24권1호
• /
• pp.59-76
• /
• 1994

Fine structure of the distal femoral epiphysis of growing mouse was studied by electron microscopy. The first morphological evidence of developing secondary center of ossification in the distal femoral epiphysis was found at newborn mouse. Ossification center was in the form of multiple foci of calcification and its cells were represented by remnant of degenerated cells within large lacunae that were separated by mineralized cartilaginous septa. Endochondral ossification beneath the articular cartilage proceeded in a less orderly manner than metaphyseal endochondral ossification. Columns of hypertrophied chondrocytes were not distinctly parallel to intercellular mineralized septa in all direction. Hypertrophied chondrocytes in the inner zone of the epiphseal center of ossification showed disintegrated. Resorption of mineralized cartilaginous septa was undertaken by perivascular cells and multinucleated chondroclasts. Resorption of the calcified cartilage was restricted to the region of ruffled border of the chondroclast. Growth along the metaphyseal side of the epiphyseal center of ossification was different from that along the articular surface. As the secondary center expanded toward the metaphyseal side, many vascular buds penetrated unmineralized cartilaginous septa and invaded viable chondrocytes. Many hypertrophied chondrocytes bodering the metaphyseal side of bone center remained viable after they became embedded in mineralized cartilaginous septa. This result suggested that the hypertrophied.

• Steel and Composite Structures
• /
• 제27권3호
• /
• pp.285-295
• /
• 2018

In this paper, the bearing capacity of a non-eccentric and eccentric tubular, concrete-filled, steel bridge pier was studied through the finite element method. Firstly, to verify the validity of the numerical analysis, the finite element analysis of four steel tube columns with concrete in-fill was carried out under eccentric loading and horizontal cyclic loading. The analytical results were compared with experimental data. Secondly, the effects of the eccentricity of the vertical loading on the seismic performance of these eccentrically loaded steel tubular bridge piers were considered. According to the simulated results, with increasing eccentricity ratio, the bearing capacity on the eccentric side of a steel tubular bridge pier (with concrete in-fill) is greatly reduced, while the capacity on the opposite side is improved. Moreover, an empirical formula was proposed to describe the bearing capacity of such bridge piers under non-eccentric and eccentric load. This will provide theoretical evidence for the seismic design of the eccentrically loaded steel tubular bridge piers with concrete in-fill.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
• /
• pp.21-22
• /
• 2015

The CFT(Concrete Filled Tube) system has been developed to behave well in a structural performance such as stiffness, stress, ductility, fire resistance that is derived from its mechanical advantages of composite structure. There were number of studies about unprotected CFT columns for improving their fire resistance through reinforcing bars or plates being placed inside the steel tube. It was also known that reinforcing plates of flat type need stiffeners in a certain distance to avoid their buckling failure so it cost as much as their using consequentially. This paper is planned to test the work of beam elements attached inner side of CFT depending on its shape. More discussions on beam's design could be followed after some fire tests accordingly conducted within this project.

• 건축역사연구
• /
• 제9권1호
• /
• pp.7-25
• /
• 2000

The purpose of this study is focused to the historic changes of Yungnam-Ru(嶺南樓), which are based on the site layout, and architectural forms in architectural building history and historic periods analyzed with the historic reference, paintings, and photos. This study is to search the alteration of the types of axis and the formation of spaces in Yungnam-Ru which is the Ru-Gak(樓閣) The conclusion of the architectural changes from the historic period and architectural form which is the belows. The first Yungnam-Ru by name had been used to be called, before it was re-called Yungnam-Ru by Kim Ju in 1365. Therefore, the hypothesis in naming Yungnam-Ru form assumption that the building under the name of Yungnam-Ru was re-named by Kim Ju from the Old Budist Temple called Yungnam-Sa, should re-considered in history. The second, it is considered that Milyang-Sibyi-Kyungdo(密陽十二景圖) as the painting can only be seen the site layout in 1542. It could be compared the differences of the site layouts from in 1542 to the present time. At that time Nyungpadang(凌派堂) was connected the main buildings called Yungnam-Ru Chimrudang(沈流堂),building was seperated with the Yungnam-Ru at that period. In 1542, the main Building(Yungnam-Ru) was consist of 5 spans of columns(from the front) and 2 spans of columns(from the side). Now, the main Building(Yungnam-Ru) has the 5 spans of columns from the front, and two spans of columns short from the side, compared to the present facade. At the past, Chimrudang(building) has the two spans of columns and one span of columns short, compared to the present facade. The third, It supposed that main building, Nyungpadang and Chimrudang in the composite of facade was connected with Wolrang(月廊) and Hunrang(軒廊) after invatioin from japan in 1592. 1844, (Chosun dynasty, Hunjong 10) the Yungnam-Ru was re-builted by maintaining the same concept in site layout of the past, and finally the three buildings was put together with Wolrang and Hunrang. As a result, the plan of the Yungnam-Ru was expanded with many aspects. From 1542 to 1844, the present site-layout gradually completed with three buildings which was spatially connected. The forth, in the middle age of Chosun dynasty, after added Gaeksa(客舍), the building is for the government officer staying temporally from outside province) in the site, the site layout was greatly changed with volume of building. In 1844, the Yungnam-Ru as the Nugak belongs to Miljukwan(密州館) was expanded spacially and formally. After that time, the burned buildings could not have been re-built because of aspects in government ability and economical ability.

• Journal of the Korean Data and Information Science Society
• /
• 제16권4호
• /
• pp.735-744
• /
• 2005

The number of electronic mail(E-mail) has been increased dramatically as a result of expanding internet and information technology. Although there are many conveniences of E-mail in the bright side, some serious problems occur because of E-mail in its dark side. One of the problems is spam-mail which is unsolicited mail and also called bulk mail. This paper presents a set of patterns of spam-mail occurrences within a week using the correspondence analysis. The correspondence analysis is an exploratory multivariate technique that converts data into a particular type of graphical display in which the rows and columns are depicted as points. One of the meaningful patterns is a great increment of adult and phishing related spam-mails at weekends so any spam-mail filters should be designed to cope with this pattern.

• KSBB Journal
• /
• 제10권5호
• /
• pp.482-490
• /
• 1995

The relationship between pressure drop and liquid flow rate, for an axial and a radial flow chromatographic column packed with compressible porous media was theoretically analyzed using modified Kozeny-Carman equation. The results were compared with experimental observations obtained using compressible DEAE-agarose as a model medium. At 2-9 psi range studied, the theoretical derivation accounting for 'gel compression' effect predicted simple Langmuirian type response of volumetric flow rate to changes in pressure drop. On the other hand, the experimental response was more or less sigmoidal. At the same pressure drop, radial column showed 2-3 times higher flow rates than those of axial column both theoretically and experimentally. Using r-HBsAg crude extract, protein resolution effects between the two types of columns at different flow rates were compared side-by-side. It turned out that, though general chromatographic behavior was very similar, axial column was somewhat superior in terms of r-HBsAg recovery yield and specificity. However, the number of theoretical plates analysis indicated the protein resolution effects were comparable.