• Advances in concrete construction
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• 제2권2호
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• pp.125-144
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• 2014

The development in roller compacted concrete (RCC) is replacing the conventionally vibrated concrete (CVC) for faster construction of dam during last three-four decades. Notwithstanding, there have been relatively less works reported on the utilization of RCC in dam constructions, especially the dams having considerable height. Further, the Ghatgar dam was the only dam in the tropical country like India constructed using the technology of RCC until two years back. However, with the completion of 102.4 m high Middle Vaitarana Dam (MVD), owned by Muncipal Corporation of Greater Mumbai (MCGM), India, has become the first largest roller compacted concrete dam. The paper traces step by step aspects of the mix design of RCC in respect of the afore-mentioned project besides the construction aspects; and also, demonstrates as to how 12.15 lacs cubic meter of roller compacted concrete was placed within the record duration of 15.2 months, thus, rendering the MVD as the ninth fastest RCC dam in the world. The paper also discusses the various mix proportioning, quality control, constructional features and instrumentation with respect to the high RCC dam such as Middle Vaitarana.

• 한국운동역학회지
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• 제16권4호
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• pp.147-152
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• 2006

The purpose of this study was to develop the experimental machine for the putting strokes. This experimental machine is called Pendulum Putting Machine(PPM). The height of PPM is 75cm and the mass is 10kg. To make the frame of this machine, 24 and 20 diameters of iron pipes were used. Bottom of the frame(bottom girdle) was made with circle shape and top of the frame(top girdle) was made with rectangular shape. Above the top girdle, iron plate($12{\times}17{\times}0.5cm$) was placed to connect the ball bearing. At the top of the frame two ball bearings with axis were placed for the diverse lies of putters and irons. To verify usefulness of this machine, experiments were executed with the PPM. Two major experimental conditions were hitting points(sweet spot, toe side, heel side) and hitting places(bottom, 3cm before bottom, 3cm after bottom). Eleven different cases were tested. The results showed that the diversity of the ball placement(distance and direction) was acceptable(distance range, 2.70-5.87 standard deviation; direction range, 1.71-4.65 standard deviation). Overall the Pendulum Putting Machine is very useful for the study of putting and driving strokes.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.359-360
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• 2009

본 연구는 실제 현장 적용 타설고를 고려한 Mock-up 시험을 통해 슬래그 시멘트와 저발열 시멘트 및 유로폼과 리브라스 거푸집 적용에 따른 매스콘크라트의 거동을 알아보고자 하였다. 먼저 시험체의 수화열 계측을 실시하여 각각의 수화발열특성을 살펴보았다. 모르타르 유출량 시험, 코어 및 표준수중양생 공시체의 압축강도, 염소이온침투저항생시험을 통한 내구성을 비교하여 해양 환정에 노출된 매스콘크리트 타설 시 공기단축 및 수화열 저감, 내구성 확보와 같은 안정적 품질확보를 위한 기초자료를 제공하는데 그 목적을 두었다.

• 한국공간구조학회논문집
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• 제16권1호
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• pp.73-84
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• 2016

This study analyzes the four composition elements : profile, anchorage and connection, material and member rigidity, stability, as the main composition design elements of flexure structure systems, in order to explore possibilities for more various structure designs in architectures with flexure structure system. It also examines typical design methods that use the mentioned four composition elements. At the results, this research presents an understanding of the differences between funicular shape and non-funicular shape and mechanical features of the shapes in the profile element, regarding to the ratio of rise height to span length(f/l). Also, the typical design methods are presented for the designable usages of the hinge joints and the fix joints, and for the applications of member rigidity expressed by the index of the ratio of member depth to span length(d/l). And it was presented that connection styles, addition of brace members, placement of shear walls are the main design methods in the stability element. This data would be useful to architectural designs concerning integrated design with structures.

• Computers and Concrete
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• 제26권5호
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• pp.429-438
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• 2020

To shorten the construction times of nuclear facility structures, three high-strength concrete mixtures were developed with specific consideration given to their curing temperatures, their economic efficiency, and the practicality of their quality control. This study was conducted to examine the temperature rise profiles of these three concrete mixtures and the potential for early-age thermal cracking in the primary containment vessel of a nuclear reactor with a wall thickness of 1200 mm. The one-layer placement height of the concrete for the primary containment vessel was increased from the conventional 3 m to 3.5 m. A nonlinear finite element analysis (FEA) was conducted using the thermal properties of concrete determined from the isothermal hydration and adiabatic hydration tests, and tuned through comparisons made with temperature rise profiles obtained for 1200-mm-thick mock-up wall specimens cured at temperatures of 5, 20, and 35℃. The hydration heat performance of the three concrete mixtures and their potential to produce thermal cracking in nuclear facilities indicate that the mixtures have considerable potential for practical application to the primary containment vessel of a nuclear reactor at various curing temperatures, fulfilling the minimum requirements of the ACI 301 and minimizing the likelihood of the occurrence of thermal cracks.

• 한국가정과학회지
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• 제1권2호
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• pp.100-112
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• 1998

The purpose of this study is to investigate the torso patterns by analyzing sensory evaluations. The anthropometric measurements for female college students were obtained between March and October in 1998, and a total of 197 anthropomatric data was used for the somatotype analysis. The appearance and fit of three kinds of torso patterns(ESMOD, FIT, and Muller & sohn) were evaluated by expert panel and the subjects. The results of the anthropometric measurements and sensory evaluations are as follows; The mean height of the anthropometric data for 197 students is 158.98cm. The largest proportion of the three somatotypes(H, M and A type) is big hip type(A type) consisting of 47.7% of all the respondents. The result of the torso pattern evaluations by expert panel indicates that the ESMOD pattern obtains the highest rating in general acceptability. A significant difference(p<.05) in the responses to two questions, the placement of the waist dart, and the gapping & creasing at back hip area was found. The ESMOD and Muller & sohn patterns are given the highest rating in the general acceptability. The result of the evaluation was obtained by the subjects. (Korean J. Human Ecology 1(2):100∼112, 1998)

• Structural Engineering and Mechanics
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• 제23권1호
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• pp.43-61
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• 2006

An investigation of the effectiveness of the interface treatment when column concrete jacketing is performed is presented. Alternative methods of interface connection were used in order to investigate the performance of strengthened concrete columns. These connecting techniques involved roughening the surface of the original column, embedding steel dowels into the original column and a combination of these two techniques. The experimental program included three strengthened specimens, one original specimen (unstrengthened) and one as-built specimen (monolithic). The specimens represented half height full-scale old Greek Code (1950's) designed ground floor columns of a typical concrete frame building. The jackets of the strengthened specimens were constructed with shotcrete. All specimens were subjected to displacement controlled earthquake simulation loading. The seismic performance of the strengthened specimens is compared to both the original and the monolithic specimens. The comparison was performed in terms of strength, stiffness and hysteretic response. The results demonstrate the effectiveness of the strengthening methods and indicate that the proper construction of a jacket can improve the behaviour of the specimens up to a level comparable to monolithic behaviour. It was found that different methods of interface treatment could influence the failure mechanism and the crack patterns of the specimens. It was also found that the specimen that combined roughening with dowel placement performed the best and all strengthened columns were better at dissipating energy than the monolithic specimen.

• Wind and Structures
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• 제14권1호
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• pp.55-70
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• 2011

This study investigates the design criteria required for wind barriers to protect vehicles running on an expressway under a high side wind. At the first stage of this study, the lateral deviations of vehicles in crosswinds were computed from the commercial software, CarSim and TruckSim, and the critical wind speeds for a car accident were then evaluated from a predefined car accident index. The critical wind speeds for driving stability were found to be 35 m/s for a small passenger car, yet 30 m/s for a truck and a bus. From the wind tunnel tests, the minimum height of a wind barrier required to reduce the wind speed by 50% was found to be 12.5% of the road width. In the case of parallel bridges, the placement of two edge wind barriers plus one wind barrier at center was recommended for a separation distance larger than 20 m (four lanes) and 10 m (six lanes) respectively, otherwise two wind barriers were recommended.

• 한국산업융합학회 논문집
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• 제23권6_1호
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• pp.907-915
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• 2020

Specification selection, Layout, specifications and combinations of Power Drives, and Ship motions were studied for FGPP(Floating Gas-fired Power Plants), which are still needed in areas such as the Caribbean, Latin America, and Southeast Asia where electricity is not sufficiently supplied. From this study, the optimal equipment layout in ships was derived. In addition, the difference between engine and turbine was verified through LCOE(Levelized Cost of Energy) comparison according to the type and combination of Power Drives. Analysis of Hs(Significant Height of wave) and Tp(spectrum Peak Period of wave) for places where this FGPP will be tested or applied enables design according to wave characteristics in Brazil and Indonesia. Normalized Sloshing Pressures of FGPP and LNG Carrier are verified using a sloshing analysis program, which is CFD(Computational Fluid Dynamics) software developed by ABS(American Bureau of Shipping). Power Transmission System is studied with Double bus with one Circuit Breaker Topology. A nd the CFD analysis allowed us to calculate linear roll damping coefficients for more accurate full load conditions and ballast conditions. Through RAO(Response Amplitude Operator) analysis, we secured data that could minimize the movement of ships according to the direction of waves and ship placement by identifying the characteristics of large movements in the beam sea conditions. The FGPP has been granted an AIP(Approval in Principle) from a classification society, the ABS.

• Ocean Systems Engineering
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• 제14권2호
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• pp.157-169
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• 2024

The sudden release of water from a dam failure can trigger bores on a flat surface and exert substantial impact forces on structures. This flow poses a high-risk flood hazard to downstream urban areas, making it imperative to study its impact on structures and devise effective energy dissipators to mitigate its force. In this study, a combination of Genetic Algorithm optimization and numerical modeling is employed to identify the optimal energy dissipator. The analysis reveals that a round arc-shaped structure proves most effective, followed by a triangular shape. These shapes offer wide adaptability in terms of structure dimensions. Structures with higher elevation, especially those with round or triangular shapes, demonstrate superior energy dissipation capabilities. Conversely, square-shaped structures necessitate minimal height to minimize impact forces. The optimal width for dissipating energy is found to be 0.9 meters, allowing for effective wave run-up and propagation. Furthermore, the force exerted on structures increases with higher initial water levels, but diminishes with distance from the dam, highlighting the importance of placement in mitigating impact forces.