• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.343-344
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• 2008

본 논문에서는 고층건물의 철골 구조물의 자동화된 볼트 체결을 위해 볼팅로봇에 장착된 카메라에 의한 영상정보를 처리하여 볼트 구멍을 인식하고 제어시스템에게 볼트 구멍의 위치를 알려주는 시스템을 제안한다. 볼팅로봇 전면에 설치된 광각 카메라를 이용하여 목표물까지 이동하고 로봇의 팔에 장착된 소형 카메라로 볼트 구멍을 인식하는 알고리즘을 제안하고 실제 볼팅로봇에 적용하여 그 성능을 평가하였으며 이는 볼팅로봇의 성능향상에 기여할 것이다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.4
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• pp.12-17
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• 2011

This paper gives a review of finite element model for the analysis of fastening as practical points of view. Different mechanical properties of plate-fastener systems are analyzed. Calculations of the system properties are described as well as the technique of their application in model. Analysis has been performed for calculating the load distribution in multi-joint and the results are compared using the several models. The effects of fastener-hole clearance on the load distribution in multifastener joints are presented. And the stress analysis method have been reviewed for failure analysis of mechanical joint of composite laminate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.820-825
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• 2004

The floating ring seal is used in an oxidizer and a fuel pump of the turbo pump unit in the liquid rocket engine to optimize a leakage without rubbing phenomenon. The damper floating ring seal, one of the floating ring seals, is with round hole pattern surfaces. It can reduce the leakage by increased friction factor that obtained from experimental data. In this paper, the leakage test about floating ring seal and damper floating ring seal was conducted. The test result showed the leakage performance of damper floating ring seal was better than the leakage performance of floating ring seal. With the leakage test the lock-up and rotation test about seal was conducted and that position is measured. The relatively large lock-up eccentric ratio was obtained from the test result of damping floating ring seal. The attitude angle of seal increases with increasing of shaft rotation

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.232-238
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• 1997

In this paper, a theoretical method is presented to design a hydraulic control valve system that consist of an important component in the hydraulic snubber. The hydraulic snubber is used essentially to support the piping systems at power plants. To calculate the force due to pressure drop and flow rate in the valve orifice and by-pass hole, Bernoulli equation is used. The Reynolds equation are numerically analyzed in the clearance gap between the valve cone and valve seat to estimate the friction force and leakage flow rate. Based on the detailed theoretical data, we developed successfully the hydraulic snubber for power plants.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.161-164
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• 1999

In order to investigate the effect of punching condition on the stretch flange formability of sheet for deep drawing hole expansion tests at various edge condition were done. Edge conditions were changed by altering tool clearances artifical defects grinding and deburring. For a determination of optimum edge condition of side panel of automobile punched section analysis and forming results were studied and the laboratory test results were used. In case of considered side panel tool clearance should be less than 15% and punched edge should be uniform without defects for safe forming

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.648-651
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• 2008

Numerical calculations are performed to simulate the film cooling effect of turbine blade tip with squealer rim. Because of high temperature of inside rim, squealer rim is damaged easily. Therefore many various cooling systems were used. The calculations are based on 100,000 Reynolds number in linear cascade model. A blade has 2% tip clearance and 8.4% rim height. The axial chord length and turning angle is 237mm, 126$^{\circ}$. Numerical calculations are performed without and with film cooling. In a film cooling in the cavity, hot spots of cavity were cooled effectively. However hot spots of suction side rim still remains. The CFD results show that the circulation flow in cavity of squealer tip affects the temperature rise of squealer rim. To maintain the blade integrity and avoid the excessive hot spot of blade, rearrangement of cooling hole is needed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.9 s.252
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• pp.913-920
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• 2006

Three-dimensional flow and aerodynamic loss in the tip-leakage flow region of a high-turning first-stage turbine rotor blade with a squealer tip have been measured with a straight miniature five-hole probe for the tip gap-to-chord ratio, h/c, of 2.0%. This squealer tip has a indent-to-chord ratio, $h/{st}/c$, of 5.5%. The results are compared with those for a plane tip $(h_{st}/c=0.0%)$. The squealer tip tends to reduce the mass flow through the tip gap and to suppress the development of the tip-leakage vortex. Therefore, it delivers lower aerodynamic loss in the near-tip region than the plane tip does. At the mid-span, however, the aerodynamic loss has nearly the same value for the two different tips.

• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.109-121
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• 2022

Twelve push-out test specimens were conducted with various parameters to study the static and fatigue performance of a new through-bolt shear connector transferring the shear forces of interface between prefabricated hybrid fiber reinforced concrete (HFRC) slabs and steel girders. It was found that the fibers could improve the fatigue life, capacity and initial stiffness of through-bolt shear connector. While the bolt-hole clearance reduced, the initial stiffness, capacity and slippage of through-bolt shear connector increased. After the steel-concrete interface properties were improved, the initial stiffness increased, and the capacity and slippage reduced. Base on the test results, the equation of the load-slip curve and capacity of through-bolt shear connector with prefabricated HFRC slab were obtained by the regression of test results, and the allowable range of shear force under fatigue load was recommended, which could provide the reference in the design of through-bolt shear connector with prefabricated HFRC slabs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.1664-1670
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• 2015

As journal bearing has a sliding motion between the shaft and bearing with lubricating oil, it produces a hydrodynamic lubrication condition. Journal bearing can receive a large force because it takes a distributed load at the large friction face. As the oil groove or oil hole is made in the journal bearing surface for the journal bearing smoothly working under a hydrodynamic lubrication condition, sufficient lubricating oil is supplied through the clearance of journal bearing. The performance of the journal bearing is changed according to the shapes, sizes and positions of an oil groove. In this paper, the flow rate according to the oil groove shapes (triangle, semicircle and rectangle) among the various oil supply conditions was measured. The shape that discharges the highest flow rate was observed and the groove shape of optimal performance for the journal bearing was determined. The results showed that the flow rate increases with decreasing operating temperature, the influence of temperature on the flow rate decreased with increasing rotational speed, and flow rate in the triangular groove shape was greater than in other shapes.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.313-319
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• 2019

The A-KRS (Advanced Korean Reference Disposal System) is the disposal concept for pyroprocessed waste, which has been developed by the Korea Atomic Energy Research Institute. In this disposal concept, the amount of high-level radioactive waste is minimized using pyrochemical process, called pyroprocessing. The produced pyroprocessed waste is then solidified in the form of monazite ceramic. The final product of ceramic wastes will be disposed of in a deep geological repository. By the way, the decay heat is generated due to the radioactive decay of fission products and raises the temperature of buffer materials in the near field of radioactive waste repository. However, the buffer temperature must be kept below $100^{\circ}C$ according to the safety regulation. Usually, the temperature can be controlled by variation of the canister interdistance. However, KAERI has modelled thermal analysis under the boundary condition, where the waste canisters are in direct contact with each other. Therefore, a reliable temperature analysis in the disposal system may fail because of unknown thermal resistence values caused by the spatial gap between waste canisters. In the present work, we have performed thermal analyses considering the gap between heating elements and canisters at the beginning of canister loading into the radioactive waste repository. All thermal analyses were performed using the COMSOL software package.