• KEPCO Journal on Electric Power and Energy
• /
• v.5 no.4
• /
• pp.257-262
• /
• 2019

Lattice steel towers for overhead transmission lines have been replaced by tubular steel poles due to the visual impact of large and complex shape of truss type. Demand for tubular steel poles consisting of a single frame member continues to grow because of its advantages such as visual minimization, architectural appeal and minimal site consumptions. However, there are some constraints on the transportation and construction. As the diameter of tower base has been enlarged, it may exceed minimum height limit required to pass the tunnel in case of land transportation. Also, in a narrow place where it is not easy to secure the installation areas such as mountainous places, there might be some areas wherein it must secure a wide working space so that large vehicles and working cranes will be allowed to enter. In this paper, we presented a vertical separated tubular steel pole, which is a new type of support that can be implemented for general purpose such as mountainous areas or narrow areas to improve the issues raised by breaking away from the conventional design and fabrication methods. Technical approaches for overcoming the limit of the cross-sectional size is to separate and modularize the cross-section of the tubular steel pole designed with a size that cannot be carried or assembled, and to lighten it with a weight capable of being transported and assembled in a narrow space or mountainous area. As a result of this research, it will be possible to enter small and medium sized vehicles in locations where it is restricted to transport by large-sized vehicles. In the case of mountainous areas, it will be possible to divide it into a weight capable of being carried by a helicopter and it will be easy to adjust and fabricate it with individual modules. Furthermore, in order to break away from the traditional construction method, we proposed the equipment that can be applied to the assembly of Tubular Steel Pole without using a large crane in locations where there is no accessible road or in locations wherein large cranes cannot enter. In particular, this paper shows the movable assembling equipment and some methods that are specialized for vertical separated tubular steel pole consisting of members with reduced weight. The proposed assembly equipment is a device for assembling the body of the Tubular Steel Poles. It will be installed inside the support and the modules can be lifted by using the support itself.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.4
• /
• pp.409-417
• /
• 2013

Mu-communication board supported by multi-communication is designed with Atxmega 128A1 which is a low power energy consuming of 8-bit microcontroller. ATxmega128A1 microcontroller consists of 8 UART(Universal asynchronous receiver/transmitter) ports which can be setting appropriate user interface having command line interpreter(CLI) program with each port, 2 kbytes EEPROM, 128 kbytes flash memory, 8 kbytes SRAM. 8 URAT ports are used for the multi communication modem, GPS module, etc. and EEPROM is used for saving a configuration for program running, and flash memory of 128 kbytes is used for storing a Firm Ware, and 8 kbytes SRAM is used for stack, storing memory of global variables while program running. If we uses the hybrid communication of path optimization of VHF, TRS and CDMA to remote control AtoN(aid to navigation), it is able to remove the communication shadow area. Even though there is a shadow area for individual communication method, we can select an optimum communication method. The compatibility of data has been enhanced as using of same data frame per communication devices. For the test, 8640 of data has been collected from the each buoy during 30 days in every 5 minutes and the receiving rate of the data has shown more than 99.4 %.

• Journal of the Korean association of regional geographers
• /
• v.9 no.4
• /
• pp.461-480
• /
• 2003

This paper is to consider the new urbanization process of Daegu in the 1990s, especially with its economy, politics, social culture, environment and space. In the economic aspect, the industrial structure of Daegu has shifted from the manufacturing- centered economy to the service economy. But it has not yet overcome the linear frame of industrial structure still relying on the textile industry, though the degree of industrial specialization has increased in the part of the fabricated metal products and the precision and optical instrument. In the political situation that the implementation of the local self-government has made the relation between localities more competitive, the local government of Daegu has led a boom for boosting the regional economic growth, organizing private-public-research relations to improve the weakening regional investment and production function. In the social and cultural aspect of the new urbanization, the investment into the soft-ware facilities has been increased, and the urban festivals have been changed so as to revitalize the regional economy. In the environmental aspect, as the self-government system has launched, conflicts around values and interests of local governments have revealed frequently due to locations of infra-structures and of abhorrence facilities. Finally, seen from the spatial dimension of the city, the extension of residential areas and unregulated use of urban space have a result of inefficience of land-use, and this kind of unplanned outer expansion of the city has brought about with further separation of house and working place, and increasing distance of movements and the an urban spatial structure which requires more energy consumption.

• Korean Journal of Environmental Agriculture
• /
• v.8 no.2
• /
• pp.142-147
• /
• 1989

In this report, we set up a simple device which enabled us to obtain data useful to estimate the relative capacity of thermal energy retention of greenhouse built with various plastic coverings. A box($20cm{\times}20cm{\times}30cm$) framed with flexiglass at the edges and covered with thin plastic films was made, in which were placed a thermostat-controlled nichrom wire heater and a thermal probe made of thermister to monitor temperature changes. A wheaston-bridge type transducer and a chart recorder were used to record the changes of temperature inside the box The data obtained by using the device showed that the relative rate of heat toss through plastic films with identical thickness decreased in the order of PE film>EVA film>PVC film and that IR additives such as fine silica gel improved the insulating power of plastic films. This observations are in well accord with general information, demostrating the feasibility of the device in usefulness for the purpose of screening of various commercial plastic coverings.

• Journal of the Korean Society for Advanced Composite Structures
• /
• v.2 no.4
• /
• pp.1-10
• /
• 2011

This study investigates the performance of composite (steel-concrete) frame structures through numerical experiments on individual connections. The innovative aspects of this research are in the use of connections between steel beams and concrete-filled tube (CFT)columns that utilize a combination of low-carbon steel and shape memory alloy (SMA) components. In these new connections, the intent is to utilize the recentering provided by super-elastic shape memory alloy tension bars to reduce building damage and residual drift after a major earthquake. The low-carbon steel components provide excellent energy dissipation. The analysis and design of these structures is complicated because the connections cannot be modeled as being simply pins or full fixity ones they are partial restraint (PR). A refined finite element (FE) model with sophisticated three dimensional (3D) solid elements was developed to conduct numerical experiments on PR-CFT joints to obtain the global behavior of the connection. Based on behavioral information obtained from these FE tests, simplified connection models were formulated by using joint elements with spring components. The behavior of entire frames under cyclic loads was conducted and compared with the monotonic behavior obtained from the 3D FE simulations. Good agreement was found between the simple and sophisticated models, verifying the robustness of the approach.

• Journal of Korean Society of Steel Construction
• /
• v.28 no.6
• /
• pp.439-448
• /
• 2016

Extended end-plate connections(EEPC) are a type of connection applied in Pre-Engineered Building structures comprising beam-column connections of steel structures or tapered members. Extended end-plate connections(EEPC) show different behavioral characteristics owing to the influence of plate thickness, gauge distance of high strength bolt, diameter of high strength bolt frame, and the number of high strength bolts. In the USA and Europe, extended end-plate connections(EEPC) are applied in beam-column connections of steel structures in various forms; however, these are not widely applied in structures in Korea.This can be attributed to the fact that the proposal of design strength types for extended end-plate connections(EEPC), proposal of connection specifications, evaluation of seismic performance, and are not being performed appropriately. Therefore, the purpose of this study is to provide basic data for the domestic application of Unstiffened extended endplate connections. To realize this, nonlinear finite element analysis was conducted on a 12-mm thick Unstiffened extended endplate connections.

• Journal of Technology Innovation
• /
• v.21 no.1
• /
• pp.303-330
• /
• 2013

Korea has started new value creation which is the post catch-up innovation system from the catch-up innovation. Post catch-up innovation system is becoming the main R&D issue for Korea and is needed for the new concept of R&D management and planning frame. This study posed questionnaires : how to promote the knowledge creation in technology planning and what the role of organizational learning in the technology planning is. This paper suggests the relationship of success factors of knowledge creation in technology planning which is organized and operated by experts with different background. Based on the prior research on organizational learning, communications and collaborative interactions, four hypotheses that factors of knowledge creation in technology planning have positive relationship with organizational learning are extracted. This study adopts Structural Equation Modeling(SEM) to analyze the relationship between organizational learning and successful technology planning. The approach based on organizational learning and interaction will be useful for constructing the planning framework in the era of post catch-up innovation. This paper, therefore, suggests the possibility of new theoretical development and new research agenda.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.4
• /
• pp.567-576
• /
• 2017

In a performance-based design, the structural safety is estimated from pre- defined damage states and corresponding damage indices. Both damage states and damage indices are well defined for above-ground structures, but very limited studies have been performed on underground structures. In this study, we define the damage states and damage indices of a cut-and-cover box tunnel which is one of typical structures used in metro systems, under a seismic excitation from a series of inelastic frame analyses. Three damage states are defined in terms of the number of plastic hinges that develop within the structure. The damage index is defined as the ratio of the elastic moment to the yield moment. Through use of the proposed index, the inelastic behavior and failure mechanism of box tunnels can be simulated and predicted through elastic analysis. In addition, the damage indices are linked to free-field shear strains. Because the free-field shear strain can be easily calculated from a 1D site response analysis, the proposed method can be readily used in practice. Further studies are needed to determine the range of shear strains and associated uncertainties for various types of tunnels and site profiles. However, the inter-linked platform of damage state - damage index - shear wave velocity - shear strain provides a novel approach for estimating the inelastic response of tunnels, and can be widely used in practice for seismic designs.

• Journal of the Society of Naval Architects of Korea
• /
• v.39 no.3
• /
• pp.48-56
• /
• 2002

The flow characteristics around KRISO 3600TEU container ship model have been experimentally investigated in a circulating water channel. The instantaneous velocity vectors were measured using 2-frame PIV measurement system. The mean velocity fields and turbulent statistics including turbulent kinetic energy and vorticity were obtained by ensemble-averaging 400 instantaneous velocity fields. The free stream velocity was fixed at 0.6m/s and the corresponding Reynolds number was $9{\times}10^5$. The test sections were divided into two regions, three transverse sections of the wake region(Station -0.5767, -1, -3) and five longitudinal sections of the wake((Z/(B/2)=0, 0.1, 0.2, 0.4, 0.6). In the wake region, large-scale longitudinal vortices of nearly same strength are symmetric with respect to the wake centerline and a relatively weak secondary vortex is formed near the waterline. With going downstream, the strength of longitudinal vortex is decreased and the wake region expands.

• Journal of the Korea Concrete Institute
• /
• v.24 no.3
• /
• pp.259-266
• /
• 2012

A general earthquake resistant design philosophy of ductile frame buildings allows beams to form plastic hinges adjacent to beam-column connections. In order to carry out this design philosophy, the ultimate bond or shear strength of the beam should be greater than the flexural yielding force and should not degrade before reaching its required ductility. The behavior of RC members dominated by bond or shear action reveals a dramatic reduction of energy dissipation in the hysteretic response due to the severe pinching effects. In this study, a method was proposed to predict the deformability of reinforced concrete members with short-span-to-depth-ratios, which would result in bond failure after flexural yielding. Repeated or cyclic loading produces a progressive deterioration of bond that may lead to failure at lower cyclic bond stress levels. Accumulation of bond damage is caused by the propagation of micro-cracks and progressive crushing of concrete in front of the lugs. The proposed method takes into account bond deterioration due to the degradation of concrete in the post yield range. In order to verify bond deformability of the proposed method, the predicted results were compared with the experimental results of RC members reported in the technical literature. Comparisons between the observed and calculated bond deformability of the tested RC members showed reasonably good agreement.