• Wind and Structures
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• v.17 no.3
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• pp.299-315
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• 2013

Numerical research on four typical configurations of noise mitigation structures and their characteristics of wind loads are reported in this paper. The turbulence model as well the model parameters, the modeling of the equilibrium atmospheric boundary layer, the mesh discretization etc., were carefully considered in the numerical model to improve the numerical accuracy. Also a numerical validation of one configuration with the wind tunnel test data was made. Through detailed analyses of the wind load characteristics with the inclined part and the wind incidence angle, it was found that the addition of an inclined part to a noise mitigation structure at-grade would affect the mean nett pressure coefficients on the vertical part, and that the extent of this effect depends on the length of the inclined part itself. The magnitudes of the mean nett pressure coefficients for both the vertical part and the inclined part of noise mitigation structure at-grade tended to increase with length of inclined part. Finally, a comparison with the wind load code British/European Standard BS EN 1991-1-4:2005 was made and the envelope of the mean nett pressure coefficients of the noise mitigation structures was given for design purposes. The current research should be helpful to improve current wind codes by providing more reasonable wind pressure coefficients for different configurations of noise mitigation structures.

• Journal of the Korean Geotechnical Society
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• v.25 no.5
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• pp.65-73
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• 2009

Large scale model tests and numerical analyses are performed to investigate the stress distribution of pillar due to surface loading nearby two-arch tunnel which is constructed in the regularly jointed rocks. It is observed that the influence of discontinuities on the stress distribution in the discontinuous rock mass and the underground stresses induced by surface loading are greater than those of linear elastic theory. Especially, lines of equal stresses are developed to the direction of inclination according to the inclined grade. In cases of discontinuities imbedded in parallel with or vertical to the ground, the pressure bulbs are formed symmetrically, however, the inclined ones result in stress distribution in parallel with and vertical to the planes of discontinuities. Results indicated that stress distribution is seriously affected by the angle of discontinuity. When stresses propagating to the pillar need to be estimated, relative location of surface loading, grade of discontinuous plane, and location of two-arch tunnel should be carefully considered.

• International Journal of High-Rise Buildings
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• v.3 no.1
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• pp.35-48
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• 2014

In designing a 300 meter high skyscraper expected to be the tallest building in Japan, an earthquake-ridden country, we launched on the full-scale performance based design to ensure redundancy and establish new specifications using below new techniques. The following new techniques are applied because the existing techniques/materials are not enough to meet the established design criteria for the large-scale, irregularly-shaped building, and earth-conscious material saving and construction streamlining for reconstructing a station building are also required: ${\bullet}$ High strength materials: Concrete filled steel tube ("CFT") columns made of high-strength concrete and steels; ${\bullet}$ New joint system: Combination of outer diaphragm and aluminium spray jointing; ${\bullet}$ Various dampers including corrugated steel-plate walls, rotational friction dampers, oil dampers, and inverted-pendulum adaptive tuned mass damper (ATMD): Installed as appropriate; and ${\bullet}$ Foundation system: Piled raft foundation, soil cement earth-retaining wall construction, and beer bottle shaped high-strength CFT piles.

• Korean Institute of Interior Design Journal
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• v.13 no.6
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• pp.107-114
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• 2004

The purpose of this study is to propose the unit plan for home office which can substitute the existing unvaried unit plan in housing and homogeneous working space in office building through the recognition of necessity and possibility about whether home-basedworkandhomeofficecanbeformedornot. Based on the above contents of a research, the following conclusions were summarized; 1. The unit plan of home office was divided into 'jointly-used type' and 'independent-separated type' in accordance with the relationship between housing and working space, 'dwelling-emphasis type' and 'working-emphasis type' in accordance with the grade of ranks between housing and working space. And the universal validity which could accept properly the dweller's characteristics was drawn by the above classification of unit types. 2. The required characteristics in a unit plan for home office were classified into flexibility, privacy, efficiency, identity, amenity. And the analyzing system of planning methodology was assigned according to dividing interior components into space-functional, space-designing interior facts. The planning methodology would have to be considered on the correlation with each required characteristic. As a result of the study, through a planning of independent-separated type, In especial, 'vertical-separated type', it was certificated that vertical-separated type could satisfy a variety of required characteristic in space-designing as well as space-functional aspect.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.47-55
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• 2012

This work deals with dynamic analysis of a monorail system with magnetic caterpillar where magnets are embedded inside each articulated element of the caterpillar, augmenting traction force of main rubber wheels to climb up slope up to 15 degree grade. Considerations are first given to determine stiffness of the primary and secondary suspension springs in order for the natural frequencies of car body and bogie associated with vertical, pitch, roll and yaw motion to be within generally accepted range of 1-2 Hz. Equations for calculating magnetic force needed to climb up given slope are derived, and a magnetic caterpillar system for 1/6 scale monorail is designed based on the derivation. To assess the hill climbing ability and cornering stability, and make sure smooth operation of the side and vertical guiding wheels which is critical for safety, a multibody model that takes into account of every component level design characteristics of car, bogie, and caterpillar is set up. Through hill climbing simulation and comparison with measurement of the limit slope, the validity of the analysis and design of the magnetic caterpillar system are demonstrated. Also by studying the curving behavior, maximum curving speed without rollover, functioning of lateral motion constraint system, the effects of geometry of guiding rails are studied.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.601-612
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• 2013

In the construction of nuclear power plants using massive walls, the use of high-strength re-bars for shear design is necessary to enhance the constructability and economy. In this study, low-rise walls (aspect ratio of 1.0) with grade 550 MPa bars were tested under cyclic loading to investigate the shear capacity and deformation capacity. The test parameters were the grade of horizontal re-bars (550 MPa, 420 MPa), strength of concrete compressive strength (46 MPa, 70 MPa), horizontal/vertical reinforcement ratio, use of lateral confinement hoops, shape of cross section, and failure modes (shear failure before or after flexural yielding). The test results were compared with those of walls with grade 420 MPa bars and predicted strength by current design codes. The results showed that the shear strength of the walls with 550 MPa bars was comparable to that of the walls with 420 MPa bars though the safe margin slightly decreased. ACI 349 provides underestimated shear strength for the walls with 550 MPa bars. In case of the wall with flexural yielding, a large deformation capacity was achieved. This result indicates that the ACI 349 provisions can be safely applied to seismic design of the low-rise walls (aspect ratio of 1.0) with grade 550 MPa bars.

• Journal of the Korean Society of Safety
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• v.35 no.4
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• pp.32-39
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• 2020

The fire compartments with fire-resistant construction are installed in the principal structural parts of a building in order to reduce damage in the event of a building fire. As a fire may spread through a crack in the fire compartment, the firestop with secured performance is used according to the procedure, methods, and standards specified in the detailed operation guideline. According to the current detailed operation guideline, vertical members (wall penetration) and horizontal members (floor penetration) are classified into different categories respective to each other for the classification of the firestop. Therefore, an accreditation applicant must apply for the performance test for each structure even if the wall and the floor have the same structure. Also, Grade T is used for the firestop that penetrates the fire compartment. However, in the case of foreign countries, the use of Grade F for the firestop is allowed even if it penetrates the fire compartment. The result of the precedent studies also showed that there was a significantly low possibility of fire to spread even if Grade F was applied for a metallic duct that penetrated the fire compartment. In this study, the improved scheme for the classification and performance standard of firestops was presented by analyzing the results of precedent studies regarding the firestop and domestic and overseas firestop qualification systems.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1821-1833
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• 2021

The gas-liquid counter-current flow limitation (CCFL) is closely related to efficient and safety operation of many equipment in industrial cycle. Air-water countercurrent flow experiments were performed in a tube with diameter of 25 mm to understand the triggering mechanism of CCFL. A parallel electrode probe was utilized to measure film thickness whereby the time domain and frequency domain characteristics of liquid film was obtained. The amplitude of the interface wave is small at low liquid flow rate while it becomes large at high liquid flow rate after being disturbed by the airflow. The spectral characteristic curve shows a peak-shaped distribution. The crest exists between 0 and 10 Hz and the amplitude decreases with the frequency increase. The analysis of visual observation and characteristic of film thickness indicate that two flooding mechanisms were identified at low and high liquid flow rate, respectively. At low liquid flow rate, the interfacial waves upward propagation is responsible for the formation of CCFL onset. While flooding at high liquid flow rate takes place as a direct consequence of the liquid bridging in tube due to the turbulent flow pattern. Moreover, it is believed that there is a transition region between the low and high liquid flow rate.

• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.109-117
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• 2006

The purpose of this study was done in order to investigate the Kinematical variables of the Rybalko motion on the Horizontal bar using the 3-dimensional cinematographic method. For this study, three excellent athletes take part in a 2003 Daegue universid game were chosen. The subject,s Rybalko motion was filmed with S-VHS camera at the speed of 60 fields per second and digitized the each fields. And the Kwon3D 3.1 version program was employed to obtain 3-dimensional data. As a result of this study. 1. A total time spent for performing Rybalko skill was Mean $2.52{\pm}0.13sec$. From starting down swing to releasing right hand the Mean $0.84{\pm}0.24sec$ was taken. 2. In the event 3 of Rybalko motion, that is, the moment which the right-hand is released on the bar, the center of mass must is employed at the position above the horizontal line of bar. In this research, the average vertical displacement(z axe) of center of mass shows $47.87{\pm}3.14cm$. 3. In the event 5, that is, the moment which the right-hand is catched again on the bar, the center of mass is employed at the position before the vertical line of bar. In this research, the average horizontal displacement(z axe) of center of mass shows $47.87{\pm}3.14cm$. 4. It has been seen that, at the moment of release of right-hand, lateral variation of center of mass is 13.395cm, vertical variation of center of mass is 7.41cm Thus, it is concluded that lateral variation of center of mass should be reduced for high grade to be acquired. 5. It has been founded that high speed of down swing influences speed of up swing, and that, in the motion of twist, the horizontal speed is little changed.

• Fashion & Textile Research Journal
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• v.6 no.1
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• pp.51-60
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• 2004

The purpose of the study was to investigate the lifestyle and individualism/collectivism of adolescents nowadays and the relationship to preferred sensation. We collected 1386 middle and high school students' data which have the answers about lifestyle, individualism/collectivism, self-esteem, school location, family members and other socio-statistical variables. The results are followings; The types of adolescents' lifestyle composed of 5 clusters, which are Pursuit of hedonic (18.9%), Adventure materialism (19.9%), Depending and pursuit of entertainment (21.4%), Internet & study (22.5%), and Strong will - economic (17.3%). Distribution of individualism/collectivism is even, and Egoist (29.8%) which belong to vertical individualism is the biggest portion. Adolescent's lifestyle has relationship to the external factors, such as school location and family income, while individualism/collectivism does rather to adolescent's own nature, such as gender and grade. Their lifestyle than their individualism/ collectivism is connected with their preferred sensation more.