• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.130-137
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• 2017

The purpose of this study is to provide a reasonable analytical method for the reinforced concrete beams which shows failure mode of shear and flexure-shear by proposing a modified formulation to consider the effect of shear deformation on the beam-column fiber element based on the flexibility method and a new constitutive law of inelastic shear response history for the section. A total of 6 specimens of reinforced concrete beams which is designed to cause shear failure before yielding longitudinal reinforcement to investigate the influence of the main experimental variables on the shear behavior characteristics and the analysis was performed by using a non-linear finite element analysis program (RCAHEST) applying the newly modified constitutive equation by the authors. The failure mode and the overall behavior characteristics until fracture are predicted appropriately for all specimens and the results are expected to be useful enough for the 3 - D analysis to carry out reliable results of large-scale and complicated structures in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.554-561
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• 2016

In this study, loading tests and a strength evaluation of the bogie frame were conducted to verify the structural safety of the bogie system in an intermodal tram, which runs with cars on a road track. The loads were calculated taking into account the features of the road track with many sharp curves and steep gradients, which are different from the track of conventional railway. They were compared with the loads specified in the previous standard specifications. After the comparison, it was confirmed that the loads acting on the bogie system operating on a road track are slightly different from the specified loads. The specified vertical load of the standard specification for all kinds of trains is conservative, but the specified lateral and longitudinal loads are less than the calculated loads. The application of the actual loads was proven to be reasonable in the development of a new railway system. Based on the defined loads, the bogie frame was fabricated on which strain gauges were attached. It was set on the large loading frame so that the stresses could be measured when loads were applied by hydraulic actuators. After measuring the stresses, it was shown that they were below the allowable stress, which verified the structural safety of the bogie frame.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.520-525
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• 2019

Mines are an important infrastructure for securing resources, but safety problems can arise in the course of operation. Recently, the mining process is very complicated due to the large scale and mechanization. Therefore, it is necessary to construct accurate geospatial information on mine for systematic and safe mine operation. The geospatial information construction using the existing total station has a disadvantage that a lot of work time is required because the target must be collimated and measured. In this study, the data of the mines were acquired with the total station and the 3D laser scanner, and the mine spatial information was constructed by using the shape based registration method. By using the static scanner data of some area applying the reference point surveying result of the total station, it was possible to construct the accurate result on the wide area acquired by the mobile scanner effectively. Also, the accuracy of the constructed geospatial information was evaluated and the deviation of mean 0.083m was shown. Point cloud products constructed through the research can contribute to the efficiency improvement of mine management by enabling quantitative analysis such as visualization of mine shape, distance, area and slope, and automation of drawing creation for cross section shape.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1222-1230
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• 2022

The rotor blade is an important component of a tidal stream turbine and is affected by a large thrust force and load due to the high density of seawater. Therefore, the performance must be secured through the geometrical and structural design of the blade and the blade structural safety to which the composite material is applied. In this study, a 1 MW class large turbine blade was designed using the blade element momentum (BEM) theory. GFRP is a fiber-reinforced plastic used for turbine blade materials. A sandwich structure was applied with CFRP to lay-up the blade cross-section. In addition, to evaluate structural safety according to flow variations, static load analysis within the linear elasticity range was performed using the fluid-structure interactive (FSI) method. Structural safety was evaluated by analyzing tip deflection, strain, and failure index of the blade due to bending moment. As a result, Model-B was able to reduce blade tip deflection and weight. In addition, safety could be secured by indicating that the failure index, inverse reserve factor (IRF), was 1 or less in all load ranges excluding 3.0*Vr of Model-A. In the future, structural safety will be evaluated by applying various failure theories and redesigning the laminated pattern as well as the change of blade material.

• Journal of the Korea Institute of Construction Safety
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• v.6 no.1
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• pp.12-18
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• 2024

High-rise, large-scale, and diversification of buildings are possible, and the reduction of concrete cross-sections reduces the weight of the structure, thereby increasing or decreasing the height of the floor, securing a large number of floors at the same height, securing a large effective space, and reducing the amount of materials, rebar, and concrete used for designating the foundation floor. In terms of site construction and quality, a low water binder ratio can reduce the occurrence of dry shrinkage and minimize bleeding on the concrete surface. It has the advantage of securing self-fulfilling properties by improving fluidity by using high-performance sensitizers, making it easier to construct the site, and shortening the mold removal period by expressing early strength of concrete. In particular, with the rapid development of concrete-related construction technology in recent years, the application of ultra-high-strength concrete with a design standard strength of 100 MPa or higher is expanding in high-rise buildings. However, although high-rise buildings with more than 120 stories have recently been ordered or scheduled in Korea, the research results of developing ultra-high-strength concrete with more than 130 MPa class considering field applicability and testing and evaluating the actual applicability in the field are insufficient. In this study, in order to confirm the applicability of ultra-high-strength concrete in the field, a preliminary experiment for the member of a reduced simulation was conducted to find the optimal mixing ratio studied through various indoor basic experiments. After that, 130 MPa-class ultra-high-strength concrete was produced in a ready-mixed concrete factory in a mock member similar to the life size, and the flow characteristics, strength characteristics, and hydration heat of concrete were experimentally studied through on-site pump pressing.

• Journal of the Korean Wood Science and Technology
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• v.13 no.1
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• pp.3-18
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• 1985

In Korea, a study on the anatomical features of pitch pine (pinus rigida Miller) branch wood through photo-microscopical method was reported in 1972 by Lee. Therefore, as a further study of Lee's on the anatomical features in branch wood of pinus rigida miller that grows in Korea, compression wood, opposite wood, and side wood were selected and treated for the purpose of comparing their structures revealed on cross and radial surface through scanning electron microscope in this study. The obtained results in this study were summarized as follows; 1. The trachied transition from earlywood to late wood is very gradual and the tracheids are nearly regular in both arrangement and size in compression wood but this transition in opposite wood and side wood is abrupt and the tracheids in opposite wood and side wood are less regular than those in compression wood. Also, the annual ring width of opposite wood is narrower than that of compression wood or side wood and the rays revealed on cross surface of side wood are more distinct than compression wood and opposite wood rays. 2. The tracheids of compression wood show roundish trends especially in earlywood but those of opposite wood and side wood show some angular trends. And intercellular space, helical cavity, and spiral check are present in both earlywood and latewood of compression wood but not present in opposite wood and side wood irrespective of earlywood and latewood. 3. The wall thickness of latewood tracheid is similar to that of earlywood tracheid in compression wood whereas the wall thickness of latewood tracheid is by far thicker than that of earlywood tracheid in opposite wood and side wood and the S3 layer of secondary wall is lack in compression wood tracheid unlike opposite wood and side wood tracheid. 4. The tracheids in compression wood are often distorted at their tips unlike those in opposite wood and side wood and the bordered pit in compression wood tracheid is located at the bottom of helical groove unlike that in opposite wood and side wood tracheid. 5. The bordered pits in radial wall of opposite wood and side wood tracheids are oval in shape but those of compression wood tracheids show some modified oval shape. 6. In earlywood of side wood, the small apertures of cross-field pits are roundish triangle to rectangle and the large one are fenestriform through the coalition of two small ones. However, the small apertures of cross-field pits are upright oval and the large ones are procumbent oval shape in earlywood of opposite wood and the apertures of cross-field pits in compression wood are tilted bifacial convex lens shape in earlywood and slit in late wood because of the border on tracheid side.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.203-210
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• 2001

In order to environmentally use wood chips manufactured from low valued forest resources by forest tendering, wood chips were used for the evaluation on chips characteristics, decomposition capability of organic wastes, and field experiment and determination of conditions for decomposer. Bioclusters manufactured by Cryptomeria japonica, commercially available wood chips in Japan, showed higher pore ratio, water reservation and water resistance, and higher cellulose content with lower hot water solubles than domestic wood chips. The useful size of wood chips for swine manure decomposition was 10 (length) ${\times}$ 5 (width) ${\times}$ 2 (thickness) mm, and cellulose contents and alkali solubles of Pinus densiflora and Populus tomentiglandulosa were similar to those of bioclusters. According to the decomposition ratio depending on wood species, it was ordered as Pinus densiflora > Pinus koraiensis > Cryptomeria japonica. The swine manure decomposition ratio depending on treatment hours by Pinus koraiensis was constant with the ratio of 15 to 16 g per hour by 1 kg of chip, indicating of daily swine decomposition amount of 390 kg by 1 ton of chips which was equal to the amount of daily swine manure production by 70 swines. Analyzing by long term used wood chips during 40 days treatment, the treated wood chips characteristically showed stable total nitrogen content, suitable pH, high accumulation of inorganic contents such as calcium, phosphorus, potassium and sodium, and no odor. During winter, the inner temperature of decomposer was kept at $43^{\circ}C$, but air bubble was occurred due to high pH and viscosity of swine manure. The most appropriate mixing ratio between wood chips and swine manure was 1 versus 2 or 3, and at more than ratio 1 versus 3, ammonia gas was caused because of anaerobic fermentation status by high moisture content of wood chips. The mixing interval of decomposer was 3 mins. per hour for the best swine decomposition.

• Journal of Bio-Environment Control
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• v.22 no.1
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• pp.27-33
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• 2013

In order to provide basic data for the development of a controlled environment cultivation system and standardization of the structures, structural status and improvement methods were investigated for the fruit tree greenhouses of grape, pear, and peach. The greenhouses for citrus and grape cultivation are increasing while pear and persimmon greenhouses are gradually decreasing due to the advance of storage facilities. In the future, greenhouse cultivation will expand for the fruit trees which are more effective in cultivation under rain shelter and are low in storage capability. Fruit tree greenhouses were mostly complying with standards of farm supply type models except for a pear greenhouse and a large single-span peach greenhouse. It showed that there was no greenhouse specialized in each species of fruit tree. Frame members of the fruit tree greenhouses were mostly complying with standards of the farm supply type model or the disaster tolerance type model published by MIFAFF and RDA. In most cases, the concrete foundations were used. The pear greenhouse built with the column of larger cross section than the disaster tolerance type. The pear greenhouse had also a special type of foundation with the steel plate welded at the bottom of columns and buried in the ground. As the results of the structural safety analysis of the fruit tree greenhouses, the grape greenhouses in Gimcheon and Cheonan and the peach greenhouses in Namwon and Cheonan appeared to be vulnerable for snow load whereas the peach greenhouse in Namwon was not safe enough to withstand wind load. The peach greenhouse converted from a vegetable growing facility turned out to be unsafe for both snow and wind loads. Considering the shape, height and planting space of fruit tree, the appropriate size of greenhouses was suggested that the grape greenhouse be 7.0~8.0 m wide and 2.5~2.8 m high for eaves, while 6.0~7.0 m wide and 3.0~3.3 m of eaves height for the pear and peach greenhouses.

• Korean Journal of Heritage: History & Science
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• v.39
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• pp.95-130
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• 2006

Japanese government college researchers, including Sekino Tadashi(關野貞), have conducted research studies and collected data, on overall Korean cultural relics as well as Silla tumuli(新羅古墳) in the early modern times under the Japanese imperialistic rule. They were supported by the Meichi government in the early stage of research, by the Chosun government-general, and by their related organizations after Korea was coIonialized to carry out investigations on Korean antiquities, fine arts, architecture, anthropology, folklore, and so on. The objective for which they prosecuted inquiries into Korean cultural relics, including Silla tumuli, may be attributed to the purport to find out such data as needed for the theoretical foundation to justify their colonialization of Korea. Such a reason often showed locally biased or distorted views. Investigations and surveys had been incessantly carried out by those Japanese scholars who took a keen interest in Korean tumuli and excavated relics since 1886. 'Korea Architecture Survey Reports' conducted in 1904 by Sekino in Korea gives a brief introduction of the contents of Korean tumuli, including the Five Royal Mausoleums(五陵). And in 1906 Imanishi Ryu(今西龍) launched for the first time an excavation survey on Buksan Tumulus(北山古墳) in Sogeumgangsan(小金剛山) and on 'Namchong(南塚)' in Hwangnam-dong, which greatly contributed to the foundation of a basic understanding of Wooden chamber tombs with stone mound(積石木槨墳) and stone chambers with tunnel entrance(橫穴式石室墳). The ground plan and cross section of stone chambers made in 1909 at his excavation survey of seokchimchong(石枕塚) by Yazui Seiyichi(谷井第一) who majored in architecture made a drawing in excavation surveys for the first time in Korea, in which numerical expressions are sharply distinguished from the previous sketched ones. And even in the following excavation surveys this kind of drawing continued. Imanishi and Yazui elucidated that wooden chambers with stone mound chronologically differs from the stone chambers with tunnel entrance on the basis of the results of surveys of the locational characteristics of Silla tumuli, the forms and size of tomb entrance, excavated relics, and so forth. The government-general put in force 'the Historic Spots and Relics Preservation Rules' and 'the Historic Spots Survey Council Regulations' in 1916, establishing 'Historic Spots Survey Council and Museum Conference. When museums initiated their activities, they exhibited those relics excavated from tumuli and conducted surveys of relics with the permission of the Chosun government-general. A gold crown tomb(金冠塚) was excavated and surveyed in 1921 and a seobong tomb(瑞鳳塚) in 1927. Concomitantly with this large size wooden chamber tombs with stone mound attracted strong public attention. Furthermore, a variety of surveys of spots throughout the country were carried out but publication of tumuli had not yet been realized. Recently some researchers's endeavors led to publish unpublished reports. However, the reason why reports of such significant tumuli as seobong tomb had not yet been published may be ascribed to the critical point in those days. The Gyeongju Tumuli Distribution Chart made by Nomori Ken(野守健) on the basis of the land register in the late 1920s seems of much significance in that it specifies the size and locations of 155 tumuli and shows the overall shape of tumuli groups within the city, as used in today's distribution chart. In the 1930s Arimitsu Kyoichi(有光敎一) and Saito Tadashi(齋藤忠) identified through excavation surveys of many wooden chamber tombs with stone mound and stone chambers with tunnel entrance, that there were several forms of tombs in a tomb system. In particular, his excavation survey experience of those wooden chamber tombs with stone mound which were exposed in complicated and overlapped forms show features more developed than that of preceding excavation surveys and reports publication, and so on. The result of having reviewed the contents of many historic spots surveyed at that time. Therefore this reexamination is considered to be a significant project in arranging the history of archaeology in Korea.