• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.451-460
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• 2010

There are many types of remodeling, however, engineers and architectures preferred to merge two or more separate units to one very spacious unit. Performing this type of remodeling, in the case of wall dominant apartments, requires partial removal of structural wall causing a concern of structural integrity. However, there are insufficient studies about partial removal, that is, openings. Presently, ACI standard have no clear way to evaluate the effect of opening on the structural wall. AIJ has the provision about strength reduction factor '$\gamma$'. However, this reduction factor cannot exactly evaluate the reduction effect of openings because this factor '$\gamma$' was determined through the elastic analysis. Therefore, in this study, 2 structural wall specimens were tested and many test results from previous studies were collected. Using these data, this study performed statistical analysis about strength of structural wall which have the opening in wall panel. And this study performed parametric study verifying shear strength reducing effect by opening area. In the results of statistical study, previous reduction factor show very conservative results because this equation did not consider other factors, reinforcement ratio and aspect ratio of openings, which was affect the shear strength of shear walls. Therefore we performed parametric study based on the test data and suggest new equation for shear strength reduction factor '$\gamma$'.

• Magazine of the Korea Concrete Institute
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• v.6 no.1
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• pp.120-130
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• 1994

The purpose of this study is to propose the analytical model for the hysteretic behavior of Reinforced Concrete bearn-column joints under various loading history. Discrete line elernents , YVith inelastic rotational spring was adopted to consider the movement of plastic hinging zone influenced by the details of longitudinal reinforcements. Also hysteretic model was constructed by excluding such variables which can not be utilized in dynamic analysis of Reinforced Concrete. structure that it will be adoptable in two-dimensional inelastic frame ardysis with 6-DOF. From the analysis of previous test results, it was found that stiffness deterioration caused by inelastic hysteretic loadings can be predicted by the functron of basic pinching coefficients, ductility ratio.and yield strength ratio of members. Strength degradation coefficients were newly proposed to explain the difference of inelastic behavior of members caused by spacing ratio of transverse steel and sectlon aspect ratio. The energy dissipation capacities calculated using the analytical model proposed in thls paper show a good agreements w~lh test results by an error of 10~20%.

• Journal of Korean Society of Steel Construction
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• v.15 no.1
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• pp.69-76
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• 2003

This paper described the ultimate strength and deformation limit of new uniplanar T-joints in cold-formed square hollow sections. The new T-joint had the configuration that only a branch member was oriented at 45 degrees to a chord member in the plane of the truss. This study focused on the branch-rotated T-joints governed by chord web failure. Based on the test results of the T-joint in cold-formed square hollow sections, the deformation lirnit was found to be 3%B for $16.7{\leq}2(B/T){\leq}33.3$ and $0.63{\leq}(b_1/B)=0.7$. Existing strength formulas for traditional T-joint were investigated, and the new strength formula for the branch-rotated T-joint was proposed. This proposed formula was based on column buckling theory considering the rounded corners of cold-formed square hollow sections. Finally, the optimization condition of yield stress and $2{\gamma}$ was recommended to select the optimized chord section.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.1
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• pp.120-130
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• 2009

This study focuses on the methodology of an ecological interpretation of Korean traditional landscapes through both life-oriented philosophy and traditional Korean philosophy which are similar to ecology. Also, useful tools for discovering an ecological technique of formation based on the ecological thoughts in ancestors' life are shown. Ecological key words as interpretative tools on the traditional landscape replaced ecological concepts in Korean culture and landscape. There are 'Bonsung(本性; the original nature)', 'Chungjeol(中絶; moderation)', 'Hyoyul(效率; efficiency)', 'Sangsaeng(相生; symbiosis)', 'Jasaeng(自生; self-generation)', 'Chunghwa(中和; neutralization)', 'Bangtong(旁通; communication)', and 'Byuntong(變通; variableness)'. For the case study, the concepts of 'spatial structure', 'constructive elements in the traditional gardens', and 'structural elements in the dwelling houses' were extracted from $\ulcorner$Imwonkyeongjeji$\lrcorner$ as an interpretative subject. As a result, Jeongon house, Jongtaek of Choi's family(the first incoming resident) showed us an ecological technique of formation by interpretation on the composing elements. Namely, they are natural dwelling houses in harmony with natural conditions and delicate relational styles. Five kinds of ecological characteristics were exposed. They are: 1. land use method following natural features('本性' '相生' '中和'), 2. physical and spatial elements in a body with nature('中絶' '相生' '中和'), 3. sustainable circulation system by recycling limited resources('效率' '自生' '旁通'), 4. use of natural materials based on the regional climate ('中絶' '效率' '自生') and 5. plane and structural decision by microclimate('效率' '自生' '變通'). Consequently, the dwelling houses and their traditional gardens aimed at the consuming space of the efficient resources by utilizing and circulating natural energy more than different types of the traditional spaces.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.56-63
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• 2009

The IEEE 802.11 standard has been used for wireless data networks such as wireless LAN, ad-hoc network, and vehicular ad-hoc network. Thus, the performance analysis of the IEEE 802.11 specification has been one of the hottest issues for network optimization and resource management. Most of the analysis studies were performed in a data plane of the IEEE 802.11 unicast. However, IEEE 802.11 broadcast is widely used for topology management, path management, and data dissemination. Thus, it is important to understand the performance of the broadcast scheme for the design of efficient wireless data network. In this contort, we analyze the IEEE 802.11 broadcast scheme in terms of the broadcast frame reception probability according to the distance from a sending node. Unlike the other works, our analysis framework includes not only the system parameters of the IEEE 802.11 specification such as transmission range, data rate, minimum contention window but also the networking environments such as the number of nodes, network load, and the radio propagation environments. Therefore, our analysis framework is expected to be used for the development of protocols and algorithms in a dynamic wireless data network.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.3
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• pp.257-268
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• 2018

We have studied the damage mechanism of a metallic thin plate by the highly energetic fragments generated from high explosive(HE) warhead. The penetration process has presumed that the velocity of a fragment is in the range of 350 m/s to 3353 m/s, the thickness of Aluminum 2024 target plate is in the range of 1 mm~6.3 mm thick. The mass of fragment with hemisphere nose shape is in the range of 0.32 g to 16 g. The analytical solution for penetration process has been derived by using the report of the project THOR. The results of analysis implied that the closed forms by an exponentially decay function well fit the change of the ballistic limit velocity, loss velocity and loss mass of fragment as the mass of fragment and the thickness of target plate increase.

• Journal of Korea Water Resources Association
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• v.42 no.5
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• pp.397-406
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• 2009

River is able to change by various environmental factors. In order to conduct restoration design of abandoned river channels, it is necessary to evaluate the river through the analysis of past and present river channels. River evaluation requires various data, such as geometry, hydraulic and hydrology, but there is a lot of difficulty to understand topographical information of river change on time and space due to a lack of past data by domestic conditions. This study analyzes the changes in past and present river channels and examines the applicability of river channel evaluation through image analysis using aerial photographs and 1918 year's map. Aerial photograph analysis was conducted by applying the image analysis method and GIS analysis method on Cheongmicheon. As a result of this analysis, we have quantitatively identified the form and size of abandoned channels, changes in the vertical-section and cross-section length of rivers, and micro-landform changes. More importantly, we verified that morphological changes in sandbars due to artificial straightening are important data in identifying the state of current river channels. In these results, although image analysis technique has limitations in two-dimensional information from aerial photographs, we were able to evaluate the changes in river channel morphology after artificial maintenance of the river.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.714-721
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• 2016

This paper proposes a simple process to fabricate tin and brass metal discs with a large surface area from molten droplets for the wet-refining process of nonferrous metals by assuming they have precious metal elements. To optimize the droplet condition in a graphite crucible, the appropriate nozzle size was determined using a simulation program (STAR-CCM+) by varying the diameters (0.5, 1.0, and 2.0 mm). The simulation results showed that both tin and brass do not fall out with a 0.5 mm diameter nozzle but they do fall out in continuous ribbon mode with a 2.0 mm nozzle. Only the 1.0mm nozzle was expected to fabricate droplets. Finally, solidified metal discs were fabricated successfully with the 1.0 mm nozzle within 10 minutes by impacting the droplets with a cooling water flowing over a Ti plate placed at the $40^{\circ}$ falling direction. The weight, average thickness, and surface area of the tin discs were 0.15 g, $107.8{\mu}m$, and $3.71cm^2$, respectively. The brass discs were 1.16 g, $129.15{\mu}m$, and $23.98cm^2$, respectively. The surface area of the tin and brass disc were 8.2 and 17.6 times the size of the tin and brass droplets, respectively. This process for precious metal extraction is expected to save cost and time.

• Cartoon and Animation Studies
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• s.46
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• pp.207-231
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• 2017

Printmaking is a field of fine arts and is placed on a vague boundary that is perceived as a commercial product with a popular character due to the speciality of editions. Advances of modern science and technology has developed a new technique of printmaking, and the fusion of printmaking and computer has shown the possibility of reproduction art. Reproduction printmaking has been heavily influenced by photography and extended areas, and the various forms of printing have brought about many changes and attempts by stimulating the possibilities of indirect art at various angles. As the history of printmaking and technology closely relate, the development of computer makes widespread expansion of plural artistry, technological and artistic change. A new conceptual shape can be created on the copied image simply by placing the material of the print on the smoothly flat surface expressed in digital form. The process and the result of such work show the area of unique work which is different from the value of the $\grave{a}$ la carte art or the characteristics of the material given by the print. The deprecated perception of reproducibility evaluated the value of the work in a direct sense of printmaking. It is undeniable that it is devalued by a bundle of works regardless of the value of each edition. However, the physical properties of the prints on the paper are brought up with hand drawings drawn on the canvas by hand. And it becomes an opportunity to show new aspect and change through the process of combining digital print information on paper. The diversity of media is sometimes a controversy of identity between art and technology. In the future, it should be discussed how the limit of the media which can be enjoyed in the field of art can be set as a standard.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.871-885
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• 2017

Nowadays, the construction of tunnels with a shallow depth drastically in urban areas increases. But the effect of sidewall displacement in shallow tunnel on its behavior is not well known yet. Most studies on the shallow tunnel have been limited to the stability and the failure of the tunnel and the adjacent ground in plane strain state. Therefore, the model tests were conducted in a model ground which was built with carbon rods, in order to investigate the impact of the tunnel sidewall displacement on the lateral load transfer to the adjacent ground. The lateral displacement of the tunnel sidewall and the load transfered to the adjacent ground were measured in model tests for various overburdens (0.50D, 0.75D, 1.00D, 1.25D). As results, if the cover depth of tunnel was over a constant depth (0.75D) in a shallow tunnel, the tunnel sidewall was failed with a constant shape not depending on the tunnel cover depth and also not affected by the opposite side of the wall. But, if the cover depth of tunnel was under a constant depth (0.75D), the failure of the tunnel sidewall could affect the opposite sidewall. In addition, if the displacement of tunnel sidewall with 50% of the critical displacement occurred, the tunnel failure was found to be at least 75%. However, additional studies are deemed necessary, since they may differ depending on the ground conditions.