• Journal of the Korean Society for Nondestructive Testing
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• v.10 no.1
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• pp.24-28
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• 1990

Centrifugally Cast Stainless Steel generally shows similar structure to the weld in austenitic stainless steel in the point of casting. When examining this material ultrasonically, the beam does not generally propagate straightforward but rather deviates from its original direction and this phenomenon called skewing is originally caused by anisotropic material. In order to calculate the beam skewing effect theoretically, work has been performed based on a model approach which has regarded material itself as having been composed of multi-layered columnar dendrite structure and the result was compared with the one from experiment. The result from both theory and experiment showed good correlation and ultrasonic beam showed the least skewing with around 45 degree incident angle.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.906-909
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• 2006

The secondary electron emission coefficient $({\gamma})$ of the cathode is an important factor for improving the discharge characteristics of AC-PDPs because of its close relationship to discharge voltage. In AC-PDPs, MgO is most widely used as a surface protective layer. In this experimental, we have investigated the electronic structure of the energy band structure of the MgO layer responsible for the high ${\gamma}$. The MgO layers have been deposited by electron beam evaporation method, where the $O_2$ partial pressures have been varied as 0, $5.2{\times}10^{-5}$ torr, $1.0{\times}10^{-4}$ torr, and $4.1{\times}10^{-4}$ torr, in this experiment. It is noted that work function that is energy gap between surface and first defect level of MgO layer has the lowest value for the highest O2 partial pressure of $4.1^{\ast}10^{-4}$ Torr.

• Journal of architectural history
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• v.9 no.2 s.23
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• pp.7-17
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• 2000

The purpose of this study is the analysis of 'perpendicular crossing Dori' with a structural character of Ddeulzip in Andong cultural area. There are many structural methods to solve the problems of Ddeuljip which is connected space in the rectangular type. There are 'Slope Base', 'Woosangak' roof, 'Seosangak' roof, and '4 beam roof framing' Moreover, they have been used 'perpendicular crossing Dori'. Its characters are as follows ; 1. The 'perpendicular crossing Dori' structure is occurred in different depth of width and length space of 'ㄱ' typed plan. At that time the beam of width is crossed in the middle of the beam of length without the order under them. 2. The 'perpendicular crossing Dori' structure is the method of free depth of width in regular distance of column which is different from general usage of balcony order. 3. The 'perpendicular crossing Dori' structure is founded north-western area of Andong Cultural Area(Bonghwa, Andong, Youngju, and Yeacheun). The best old sample was in Andong(16C) and the next is Yeacheun(17C) and the last is Bonghwa(18C). 4. The frequency in use of roof type of 'perpendicular crossing Dori' structure is 64% of 'Seosangak' and 36% of 'Woosangak'. The sample of 'Woosangak' house of 'perpendicular crossing Dori' structure is concentrated in Bonghwa. 5. The best merit of the 'perpendicular crossing Dori' structure is usage of double swing window in front of Anbang, It is the spacial success which overcomes the structural limits. And it is the structural rationality.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.2
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• pp.182-190
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• 2009

GPS receivers can be disrupted by intentional or unintentional jamming, then it is unable to receive GPS signals and it is impossible to get the correct navigation results. Anti-jamming schemes using array antennas are being studied well due to high performance of those, and the efforts to apply them to GPS receiver are also being done. A GPS receiver structure for a multiple beam-forming scheme among those schemes has been proposed in this paper, and the performance is also compared with that using a general GPS receiver structure. For a general GPS receiver structure, each satellite signal which is formed by a beam-forming scheme is summed to be processed in a part of digital signal processing. For a proposed GPS receiver structure, however, each satellite signal is respectively processed by a designated channel in a part of digital signal processing. Finally, it is confirmed that the proposed GPS receiver structure is superior to a general GPS receiver structure in a point of the carrier to noise power ratio and the navigation accuracy using a software platform.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.675-682
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• 2002

The beam of composite structure composed of the RC structure in the end part and steel structure in the central palt were investigated during cyclic loading, in order to evaluate strength, stiffness, and deformational capacity. The parameters used in this study include the amount of reinforced steel bar between the steel beam and RC structure and the existence of the sticking plate. Test results showed that all specimens had stabilized hysteresis loops. Likewise, the specimens with sticking plate had higher load-carrying capacity compared with the one without it. In addition, the stiffness of the composite structure was higher than the steel structure. All specimens also showed good rotational capacity.

• Composites Research
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• v.28 no.4
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• pp.204-211
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• 2015

This paper presents a theory related to a two-dimensional linear cross-sectional analysis, recovery relationship and a one-dimensional nonlinear beam analysis for composite wing structure with initial twist. Using VABS including a related theory, the design process of the composite rotor blade has been described. Cross-sectional analysis was performed at cutting point including all the details of geometry and material. Stiffness matrix and mass matrix were linked to each section to make 1D beam model. The 3D strain distributions within the structure were recovered based on the global behavior of the 1D beam analysis and visualize numerical results.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.3450-3462
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• 2024

This paper presents a computational framework for drop time assessment of a control element assembly (CEA) under fuel assembly (FA) deformations. The proposed framework consists of three key components: 1) finite element modeling of CEA, 2) fluid-structure interaction to compute drag force, and 3) modeling of frictional contact between CEA and FA. Specially, to accommodate the large motion of CEA, beam elements based on absolute nodal coordinate formulation (ANCF) are adopted. The continuity equation is utilized to calculate the drag force, considering flow changes in the cross-sectional area during the CEA drop. Lastly, beam-inside-beam frictional contact model is employed to capture practical contact conditions between CEA and FA. The proposed framework is validated through experiments under two scenarios: free falls of CEA within FA, encompassing undeformed and deformed scenarios. The experimental validation of the framework demonstrated that the drop time of CEA can be accurately predicted under the complex coupling effects of fluid and frictional contact. The drop times of the S-shaped deformation case is longer than those of the C-shaped deformation case, affirming the time delay due to frictional force. The validation confirms the potential applicability to access the safety and reliability of nuclear power plants under extreme conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.133-133
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• 1998

In the thin film alloy formation of the transition metals ion-beam-mixing technique forms a metastable structure which cannot be found in the arc-melted metal alloys. Sppecifically it is well known that the studies about the electronic structure of ion-beam-mixed alloys pprovide the useful information in understanding the metastable structures in the metal alloy. We studied the electronic change in the ion-beam-mixed ppt-Ct alloys by XppS and XANES. These analysis tools pprovide us information about the charge transfer in the valence band of intermetallic bonding. The multi-layered films were depposited on the SiO2 substrate by the sequential electron beam evapporation at a ppressure of less than 5$\times$10-7 Torr. These compprise of 4 ppairs of ppt and Cu layers where thicknesses of each layer were varied in order to change the alloy compposition. Ion-beam-mixing pprocess was carried out with 80 keV Ae+ ions with a dose of $1.5\times$ 1016 Ar+/cm2 at room tempperature. The core and valence level energy shift in these system were investigated by x-ray pphotoelectron sppectroscoppy(XppS) pphotoelectrons were excited by monochromatized Al K ａ(1486.6 eV) The ppass energy of the hemisppherical analyzer was 23.5 eV. Core-level binding energies were calibrated with the Fermi level edge. ppt L3-edge and Cu K-edge XANES sppectra were measured with the flourescence mode detector at the 3C1 beam line of the ppLS (ppohang light source). By using the change of White line(WL) area of the each metal sites and the core level shift we can obtain the information about the electrons pparticippating in the intermetallic bonding of the ion-beam-mixed alloys.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.6
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• pp.399-405
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• 2023

This study presents an optimal seismic design method based on genetic algorithms to induce beam-hinge collapse mechanisms in reinforced concrete moment frames. Two objective functions are used. The first minimizes the cost of the structure and the second maximizes the energy dissipation capacity of the structure. Constraints include strength conditions of columns and beams, minimum conditions for column-to-beam flexural strength ratio, and conditions for preventing plastic hinge occurrence of columns. Linear static analysis is performed to evaluate the strength of members, whereas nonlinear static analysis is carried out to evaluate energy dissipation capacity and occurrence of plastic hinges. The proposed method was applied to a four-story example structure, and it was confirmed that solutions for inducing a beam-hinge collapse mechanism are obtained. The value of the column-beam flexural strength ratio of the obtained design was found to be larger than the value suggested by existing seismic codes. A more robust strategy is needed to induce a beam-hinge collapse mode.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.3-11
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• 2005

For monitoring of the civil and building structure, optical fiber sensors are very convenient. The fiber sensors are very small and do not disturb the structural properties. They also have several merits such as electro-magnetic immunity, long signal transmission, good accuracy and multiplexibility in one sensor line. Strain measurement technologies with fiber optic sensors have been investigated as a part of smart structure. In this paper, we investigated the possibilities of fiber optic sensor application to the monitoring of beam-column joints of structures. We expect that the fiber optic sensors replace electrical strain gauges. The commercial electric strain gauges show good stability and dominate the strain measurement market. However, they lack durability and long term stability for continuous monitoring of the structures. In order to apply the strain gauges, we only have to attach them to the surfaces of the structures. In this paper, we investigate the possibility of using fiber optic Bragg grating sensors to joint structure. The sensors show nice response to the structural behavior of the joint.