• Journal of the Korean Society for Advanced Composite Structures
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• v.5 no.4
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• pp.24-35
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• 2014

An experimental study on the structural behavior of connection types between approach slab and integral abutment has been done for three typical bar connections. Typical hinge style reinforcing bar detail for its connection is preferred in order to accommodate rotation of the approach slab among engineers. However, the straight horizontal bars can be used as connection detail accomodate structural capacity. Total six specimens with three types of rebar detail are tested for direct tensile and bending load. The characteristic structural behaviors are carefully monitored and all the strain gauge data obtained are analyzed. It is shown that the structural performance of all the specimens well exceed its design allowance. Several design suggestions are given based on careful reviews on the experiment.

• Steel and Composite Structures
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• v.11 no.4
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• pp.291-305
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• 2011

The new structure consisting of continuous compound spiral hoop reinforced concrete (CCSHRC)column and steel concrete composite (SCC) beam has both the advantages of steel structures and concrete structures. Two types of beam-to-column connections applied in this structural system are presented in this paper. The connection details are as follows: the main bars in beam concrete pass through the core zone for both types of connections. For connecting bar connection, the steel I-beam webs are connected by bolts to a steel plate passing through the joint while the top and bottom flanges of the beams are connected by four straight and two X-shaped bars. For bolted end-plate connection, the steel I-beam webs are connected by stiffened extended end-plates and eight long shank bolts passing through the core zone. In order to study the seismic behaviour and failure mechanisms of the connections, quasi-static tests were conducted on both types of full-scale connection subassemblies and core zone specimens. The load-drift hysteresis loops show a plateau for the connecting bar connection while they are excellent plump for bolted end-plate connection. The shear capacity formulas of both types of connections are presented and the values calculated by the formula agree well with the test results.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.129-133
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• 1968

The writer reviewed the cutting method of webbing practiced in major countries. Cutting rhythm Bar cutting to Point Cutting) should be chosen to approach as straight as possible, therefore the knot cuttings or the side cuttings should be 1, if possile. According to calculation, an arbitrary solution to a mixed cutting was undertaken, while another cutting method, of calculation 5 and 6, was taken by a prepared table. In no case, it was consequently possible to use an unmixed cutting rhythm. Sometimes, the cutting calculated from approximate value differs from desired result, tut this defference should not be taken too significant in practice.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.7
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• pp.24-28
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• 1996

In this paper, a new measurement system has been developed for measuring servo errors of CNC machine tools. Unlike the ball link bar method using circular path, the developed system uses two orthogonal straight paths for measurement of errors, giving relatively short test length. For position measurment, linear displacement sensor and steel cube have been designed, and the software for relevant data sampling and error evaluation has been implemented.

• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.55-63
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• 2006

The purpose of this study is to prove the kinematical characteristics of Deff motion, the high bar performance, in terms of flying phases so that we can provide basic sources for improving gymnastic performance. To do this, we selected and analyzed the performance of two athletes who did Deff motion in the high bar competition of male artistic gymnastic in the 22nd Universiade 2003 Daegu. We drew the conclusions from the kinematical factors that were came out through analyzing three-dimensional cinematography of the athletes' movements, by using a high speed video camera. To make a successful performance, a performer releases the bar at a height of a high bar vertically and at a height of 82cm horizontally, and the flying performance should be made without moving forward, as maintaining the proper balance, in order to rise over 118cm high during the flying phase. When the performer is releasing the bar, an increase of the vertical speed in the center of the body and extension of a knee joint and a hip joint contribute to increasing a flying height. And when the moving body is twisted, leaning to left side is caused by the winding movement of a knee joint, which causes an unstable bar grasp. To grasp the bar stably, just before releasing the performer should gain propulsive force from twisting rotation through increasing the speed of shoulder rotation. And before the peak point, the performer should make sure of a body rotation distance over $164^{\circ}$ so that he or she can do an aerial rotary performance smoothly. When grasping the high bar, the center of the body should be above the bar and the angle of shoulder rotation should be maintained close to $540^{\circ}$ simultaneously. he high point performance(S1) has more speed on an ascending phase and less speed on a descending phase than the low point performance (S2). At the peak point, both the rotation angle of the body and that of the shoulder in high point performance are big as well. In conclusion, it is shown that a performer can make a jump toward the high bar easily with the body straight because the performer can hold the upper part of the body erect early in a descending phase.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.244-251
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• 2016

In this study, the relationship between flow characteristics and projection distance, depending on the shape was examined. A numerical investigation technique for fluid analysis of a foam monitor was developed for the prediction, comparison and validation of the actual injection performance. The foam monitor changes the flow pattern of fluid flow according to the shape, The fluid losses were calculated from the numerical investigation affecting the projection distance. The basic form of foam monitor was used as a designed shape in N. The modified model used the length increase model of the flow path, and straight line of the model. The inlet pressure was 6.5bar. The results showed that the length increase model of the flow path and straight line of the model in the nozzle projection distance had improved. The results comparing the error rates projection performance were well matched to the 7.43% obtained from the validity test of the analysis method.

• Progress in Superconductivity and Cryogenics
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• v.24 no.3
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• pp.62-67
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• 2022

Liquid hydrogen (LH₂) has a higher density than gaseous hydrogen, so it has high transport efficiency and can be stored at relatively low pressure. In order to use efficient bulk hydrogen in the industry, research for the LH₂ supply system is needed. In the high-pressure hydrogen station based on LH₂ currently being developed in Korea, a heat exchanger is used to heat up supercritical hydrogen at 700 bar and 60 K, which is pressurized by a cryogenic high-pressure pump, to gas hydrogen at 700 bar and 300 K. Accordingly, the heat exchanger used in the hydrogen station should consider the design of high-pressure tubes, miniaturization, and freezing prevention. A helical heat exchanger generates secondary flow due to the curvature characteristics of a curved tube and can be miniaturized compared to a straight one on the same heat transfer length. This paper evaluates the heat transfer performance through parametric study on the distance between coils, guide effect, and anti-icing design of helical heat exchanger. The helical heat exchanger has better heat transfer performance than the straight tube exchanger due to the influence of the secondary flow. When the distance between the coils is uniform, the heat transfer is enhanced. The guide between coils increases the heat transfer performance by increasing the heat transfer length of the shell side fluid. The freezing is observed around the inlet of distribution tube wall, and to solve this problem, an anti-icing structure and a modified operating condition are suggested.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.6
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• pp.107-115
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• 2017

This study illustrated the process of bar structure and vegetation coverage to understand historical changes of riverbed and suppose adaptive management in Tan-chun ecological landscape reserve. The study site that lower reach of the Tan-chun are known as habitats of migratory bird and aquatic species with dynamic riverbed. Aerial photos from 2006 to 2016 and surveyed vegetation data in 2006 and 2016 were used by analysis of landscape changes and comparison of vegetation coverage. Study area is classified into 3 sites (A: straight site, B: meandering site, C: meandering and junction with Yangjae-cheon). The result showed that bar area of A and C sites gradually increased, B site decreased during 10 years. Also, ratio of bar area to vegetation coverage and level of vegetation coverage increased in all sites during 10 years. All sites seem to have experienced the terrestrialization with time. On the other hand, ratio of annual vegetation increased and ratio of perennial vegetation decreased in C site in 2016 compare to 2006. Because area of Japanese Hops (Humulus japonicas) as one type of annual vegetation increased, other vegetation could not grow up by its powerful expandability. It is time to make active adaptive management based on not only continuos monitoring but also revaluation of river conditions in order to enhance habitat quality and quantity in Tan-chun ecological landscape reserve.

• Journal of KIBIM
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• v.11 no.1
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• pp.21-30
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• 2021

Reinforcing bars, a major component of the pre-fab structure, adheres to the existing on-site assembly method and attempts to develop and commercialize the technology of the pre-assembly method, but the effect is insignificant. Welded Wire / Bar Mat (WBM) has various advantages such as commercialization of rebar through machine manufacturing to improve workability, but it is different from the existing design and the construction method is different from the previous one. Therefore, to maximize the advantages of WBM and improve productivity, manufacturing, transportation, and construction from the design stage should be considered based on BIM from the initial design stage. In this paper, the concept of the design support system for the WBM was established based on the use of BIM in concrete reinforcement and the preliminary research on the WBM. WBM conversion design was performed for the existing prefabricated members, and based on this, the exchange format and system of the master prefabricated model with the WBM design data were set up. As a result of the pilot test, it was found that the traditional reinforcing bar information extracted from the master prefab model has transmitted 100% accurately. As for the WBM information, 100% of the information on the straight reinforcement was transmitted and represented, and the information on the bent reinforcement was found to have a 90% recall in the master BIM tool.

• Computational Structural Engineering
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• v.5 no.4
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• pp.133-142
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• 1992

An analytical model was developed for predicting the pullout behavior of straight beam longitudinal bars anchored at exterior beam-column connections. The model incorporates a local bond constitutive simulation capable of considering the effects of anchored bar diameter, yield strength and the spacing, concrete compressive strength, and column pressure on the bond characteristics of deformed bars in confined conditions of exterior joints. The analytical techniques adopted in this study were shown to satisfactorily predict the results of pullout tests on straight bars embedded in confined concrete specimens. An evaluation of the ACI-ASCE Committee 352 development length requirements in exterior joint conditions was made using the developed analytical approach. The results of this analytical evaluation are indicative of the conservatism of the current development length requirements in the confined conditions of exterior joints.