• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.184-190
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• 2015

On wide variety of fields, studies on active twist control are becoming more active. For effective twist control, blades have to have low torsional stresses with high torsional deformations to the same magnitude of torque acting on its cross-section. In this study, 2D sectional analysis and 3D finite element analysis were made for 5 different blades with each having different cross - sections which have different spars. The results from 2D sectional analysis, were then put into 3D blade deformation and stress calculations which lead to analysis. Outcomes from 2D and 3D analysis, showed that on the same torque and concentrated load conditions, the blade with 'C' shaped spar was the best of all the blades which were used in this study.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.4
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• pp.319-326
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• 2015

In this paper, a 3D mechanical model based on pulmonary nodule segmentation method is proposed. The proposed method has three main parts. First, an initial 3D mechanical model is generated. The model is made up of many triangle elements resulting in forming whole shape of the model as sphere. Second, points of the model are deformed, and finally internal and external energies according to each deformation are calculated. The internal energy is determined by the model shape, and the external energy is determined by intensity. After the model is deformed, the process of searching the minimum energy generated by the deformation is executed repetitively. If the model energy converges, the nodule is segmented by using the proposed model. The proposed method greatly improves the result compared with conventional methods.

• Kyungpook Mathematical Journal
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• v.63 no.3
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• pp.425-435
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• 2023

The classical Hardy Theorem on R states that a function f and its Fourier transform cannot be simultaneously very small; this fact was generalized by Miyachi in terms of L¹ + L^∞ and log⁺-functions. In this paper, we consider the k-Hankel transform, which is a deformation of the Hankel transform by a parameter k > 0 arising from Dunkl's theory. We study Miyachi's theorem for the k-Hankel transform on ℝ^d.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.3
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• pp.254-259
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• 2013

Ball screw system is widely used as a precision mechanical linear actuator that translates rotational motion to linear motion for its high efficiency, great stiffness and long life. Recently, according to the requirements of high accuracy and stiffness, the pre-load on the ball screw which means of remove the backlash in the ball screw is usually used. Because of the preload which means the frictional resistance between the screw and nut, becomes a dominating heat source and it generates thermal deformation of ball screw which is the reason for low accuracy of the positioning decision. There are several methods to solve the problem that includes temperature control, thermal stable design and error compensation. In the past years, researchers focused on the error compensation technique for its ability to correct ball screw error effectively rather than the capabilities of careful machine design and manufacturing. Significant amounts of researches have been done to real-time error compensation. But in this paper, we developed a series of cooling methods to get thermal equilibrium in the ball screw system. So we find the optimum cooling type for improving positioning error which caused by thermal deformation in the ball screw system.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.1-8
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• 2013

In this study, 120 cases of damage due to ground subsidence of city gas pipeline which is hanging on apartment outer wall were investigated. From the survey results, it was determined to be approximately 100m~200mm ground subsidence occurred and at severe damage, pipeline was cut and the gap was about 50mm between two cut pipeline. Device for measuring the amount of deformation of standing gas pipeline was designed and fabricated. And installed it on apartment outer wall for measuring the deformation due to ground subsidence, after 5 months measurement the amount of ground subsidence was measured to 1.3mm. Stress assessment was conducted based on results of ground subsidence occurred on standing gas pipeline.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.482-487
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• 2001

Leaf type foil bearings have been used successfully in many aerospace applications such as air cycle machines, turbocompressors and turboexpander. These applications are characterized by light loads, constant speeds and low to moderate temperatures. But, as system on start-up or shutdown, sliding contact between the shaft and foil surfaces cause wear. So, in present study, to understand pressure-flow characteristics and deformation of foil bearing, flow/structure interaction analysis was used. and using this method, 2D and 3D calculation was peformed for shape of foil bearing to know circumferential direction flow and leakage flow characteristics of axial direction.

• Journal of the Korean Institute of Gas
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• v.5 no.3 s.15
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• pp.9-14
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• 2001

현재까지 국내에서는 지진에 대한 위험성을 인식하고 건축물 및 교량등에 대한 내진설계 연구가 활발하게 진행중이지만 지중에 매설된 관에 관한 연구는 미약한 실정이다. 지중매설관 중 가스관의 파손은 주변의 환경과 인명에 심각한 영향을 줄 수도 있으므로 인명보호와 타시설의 보호를 위해서는 가스관의 내진설계에 대한 검토가 요구된다. 본 연구에서는 지중매설관중 가스관의 내진성을 검토하기 위해서 가스관의 파손을 일으키는 원인 중에 하나인 액상화에 의한 영구지반변형에 대하여 매설관의 거동을 분석하였다. 이를 위하여 외국의 사례를 분석하고 우리나라 가스관에 대한 해석을 수행하여 지진에 대한 안정성을 검토하였다.

• Korean Journal of Remote Sensing
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• v.35 no.6_3
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• pp.1235-1249
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• 2019

Kilauea Volcano is one of the most active volcano in the world. In this study, we used the ALOS-2 PALSAR-2 satellite imagery to measure the surface deformation occurring near the summit of the Kilauea volcano from 2015 to 2017. In order to measure two-dimensional surface deformation, interferometric synthetic aperture radar (InSAR) and multiple aperture SAR interferometry (MAI) methods were performed using two interferometric pairs. To improve the precision of 2D measurement, we compared root-mean-squared deviation (RMSD) of the difference of measurement value as we change the effective antenna length and normalized squint value, which are factors that can affect the measurement performance of the MAI method. Through the compare, the values of the factors, which can measure deformation most precisely, were selected. After select optimal values of the factors, the RMSD values of the difference of the MAI measurement were decreased from 4.07 cm to 2.05 cm. In each interferograms, the maximum deformation in line-of-sight direction is -28.6 cm and -27.3 cm, respectively, and the maximum deformation in the along-track direction is 20.2 cm and 20.8 cm, in the opposite direction is -24.9 cm and -24.3 cm, respectively. After stacking the two interferograms, two-dimensional surface deformation mapping was performed, and a maximum surface deformation of approximately 30.4 cm was measured in the northwest direction. In addition, large deformation of more than 20 cm were measured in all directions. The measurement results show that the risk of eruption activity is increasing in Kilauea Volcano. The measurements of the surface deformation of Kilauea volcano from 2015 to 2017 are expected to be helpful for the study of the eruption activity of Kilauea volcano in the future.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.151-160
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• 2004

This research addresses the experimental application of the digital close-range photogrammetric technique for 3D deformation measurement and visualization of road slope. The 3D displacements were extracted by the photo-triangulation based on the bundle adjustment method using the digital imagery. In addition, we produced the digital elevation models, the digital orthorectified images and the 3D perspective view images of the slope employing a digital photogrammetric workstation. Also the inclination map of the slope was generated as the data for monitoring and managing dangerous slopes.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.167-173
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• 2005

The Berkovich nano-indentation is an indentation test method analyzing mechanical properties of materials such as hardness and elastic modulus. The length scale of the penetration is measured in nanometers. Therefore, this method becomes widely useful for analyzing the mechanical property of thin film which can not be measured before. In this paper, comparing two results of the load-displacement curve obtained by the Berkovich nano-indentation and the 3-D finite element analysis, it was confirmed that the 3-D finite element analysis is useful. The phenomenon of pile-up and sink-in due to material properties was discussed by the finite element analysis.