• Journal of Korean Society for Geospatial Information Science
• /
• v.10 no.3 s.21
• /
• pp.115-122
• /
• 2002

The mainly used technique to rectify satellite images with distortion is to develop a mathematical relationship between the pixel coordinates on the image and the corresponding points on the ground. By defining the relationship between two coordinate systems, a polynomial model is designed and various linear transformations are used. These GCP based geometric correction has performed overall plane to plane mapping. In the overall plane mapping, overall structure of a scene is considered, but local variation is discarded. The highly variant height of region is resampled with distortion in the rectified image. To solve this problem, this paper proposed the TIN-based rectification on a satellite image. The TIN based rectification is good to correct local distortion, but insufficient to reflect overall structure of one scene. So, this paper shows the experimental result and the analysis of each rectification model. It also describes the relationship GCP distribution and rectification model. We can choose a geometric correction model as the structural characteristic of a satellite image and the acquired GCP distribution.

• Archives of Pharmacal Research
• /
• v.29 no.10
• /
• pp.840-844
• /
• 2006

For the exploration of pharmacophoric moiety of malloapelta B (1) possessing the inhibitory activity of $NF-{\kappa}B$ activation, structural variation of ${\alpha},{\beta}-unsaturated$ carbonyl motif was attempted. 1 was reduced by catalytic hydrogenation, sodium borohydride, and lithium aluminumhydride. Catalytic hydrogenation with 30 psi or 15 psi of $H_2$ gas of 1 generated 8-butyl-5,7-dimethoxy-2,2-dimethylchroman (2) and 1-(5,7-dimethoxy-2,2-dimethylchroman-8-yl)butan-1-one (3), respectively. Reduction with sodium borohydride occurred at the double bond of ${\alpha},{\beta}-unsaturated$ ketone of 1 to give 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)butan-1-one (4). Reduction of 1 with lithium aluminumhydride and then quenched with methanol and water produced unexpected products, 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-methoxy-1-butene (5) and 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-hydroxy-1-butene (6). These are formed from the isomerization of initial product 9 through the continuous conjugate carbocation intermediate 11. Addition of ethylmagnesium bromide and dimethyl malonate anion to 1 gave the conjugate adducts 7 and 8. Ethylmagesium bromide and sodium borohydride reduction unusually gave the conjugate addition due to steric congestion around carbonyl group of 1. Compound 2 exhibits the reduced inhibitory activity against $NF-{\kappa}B$ activation and the others do not show the activity. Therefore ${\alpha},{\beta}-unsaturated$ carbonyl group of 1 should be important for its inhibitory activity.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.10 no.1 s.47
• /
• pp.51-62
• /
• 2006

To dale, lots of types of tuned mass dampers are developed and investigated to reduce dynamic responses of a structure due to various causes. In this study, control performance of semi-active tuned mass damper(STMD), that can change the damping of tuned mass damper in real time based on structural responses, was investigated with respect to various types of excitation employing numerical simulation. Skyhook control algorithm was used to appropriately modulate the damping ratio of semi-active damper that composes STMD. The control effectiveness of a STMD under harmonic and random excitation were evaluated using a single-degree-of-freedom (SDOF) structure in comparison with a conventional passive tuned mass damper (TMD). The robustness of a STMD and a passive TMD were compared along with the variation of the mass of a SDOF structure. The control performance of STMD using magnetorheological (MR) damper was also investigated in this study. Based on the numerical studios, it was shown that the control effectiveness of the STMD was significantly superior to that of a passive TMD with respect to harmonic and random excitation.

• Composites Research
• /
• v.28 no.6
• /
• pp.372-377
• /
• 2015

In this study, we analyzed process numerically when a bogie frame skin is manufactured by applying resin transfer molding process using composite material instead of steel. Processing time was compared based on the various thickness of bogie frame skin and the weight variation of a skin was also considered. As a result, RTM processing time decreases and the weight of a bogie reduces as the thickness of frame skin increases with the assumption that fiber volume is constant inside the skin. By considering these results as the information to estimate the production cost, trade-off between two fields, processing time and structural properties, can be performed in design optimization to produce bogie frame.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.933-936
• /
• 2008

An engineered cementitious composite (Engineered Cementitious Composite) had been developed in previous study. Theoretical prediction of the tensile stress-strain relation of ECC is important in providing the material constitutive relation necessary for designing structural members. But, few studies have been reported with regard to predicting the tensile stress-strain relation of ECC. Prediction of the tensile stress-strain relation of ECC accounting for actual bridging curve, such as fiber dispersion is needed. The present study extends the work as developed by Kanda et al., by modeling the bridging curve, accounting for fiber dispersion, the degree of matrix spalling, and fiber rupture to predict the tensile stress-strain relation of ECC. The role of material variation in the bridging curve, such as number of effective fiber actually involved in the bridging capacity and how it affects the multiple cracking process is discussed. The approach for formulating the tensile stress-strain relation is discussed next, where the procedure for obtaining the necessary parameters, such as the crack spacing, is presented. Finally, the predicted stress-strain relation will be validated with experimental tests results.

• Journal of IKEEE
• /
• v.24 no.1
• /
• pp.284-292
• /
• 2020

SiC-based devices perform well in high-voltage environments of more than 1200V compared to silicon devices, and are particularly stable at very high temperatures. Therefore, 1700V UMOSFET has been actively researched and developed for the use of electric power systems such as electric vehicles and aircrafts. In this paper, we analysed thermal variations of critical variables (breakdown voltage (BV), on-resistance (R_on), threshold voltage (v_th), and transconductance (g_m)) for the three type 1700V UMOSFETs-Conventional UMOSFET (C-UMOSFET), Source Trench UMOSFET (ST-UMOSFET), and Local Floating Superjunction UMOSFET (LFS-UMOSFET). All three devices showed BV increase, R_on increase, v_th decrease, and g_m decrease with increasing temperature. However, there are differences in BV, R_on, v_th, g_m according to the structural differences of the three devices, and the degree and cause of the analysis were compared. All results were simulated using sentaurus TCAD.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.1727-1734
• /
• 2008

After the final closure of sea dyke, seepage behaviour of embankment is highly changed by variation of water head different between tide wave and controlled water level at fresh lake. Especially, the seepage behaviour of bottom protection layer of final closure section is more important factor for structural and functional stability of sea dyke, because of the bottom protection layer of final closure section is penetrated sea side to fresh lake. Even though bottom protection layer was filled with dredged fine sand, it has a high permeability. In this paper, mainly described about the seepage velocity and borehole image of bottom protection layer filled with dredged sand after final closure. Various in-situ tests such as BIPS (Borehole Image Processing System) and ABI (Acoustic Borehole Imager) survey, wave velocity measuring, and color tracer survey were conducted to evaluate the seepage behavior of bottom protection layer. Based on the in-situ tests, the bottom protection layer of final closure section was almost filled with dredged sand which is slightly coarse grain sand and there have sea water flow by water head different between tide wave and controlled water level at fresh lake. Also, comply with tracer survey results, the sea water flow path was not exist or generated in the bottom protection layer. However, because of this result not only short term survey but also just one test borehole survey results, additional long term and other borehole tests are needed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.06a
• /
• pp.239-242
• /
• 1998

Ca $F_2$ films have superior gate insulator properties than conventional gate insulator such as $SiO_2$, Si $N_{x}$, $SiO_{x}$, and T $a_2$ $O_{5}$ to the side of lattice mismatch between Si substrate and interface trap charge density( $D_{it}$). Therefore, this material is enable to apply Thin Film Transistor(TFT) gate insulator. Most of gate oxide film have exhibited problems on high trap charge density, interface state in corporation with O-H bond created by mobile hydrogen and oxygen atom. This paper performed Ca $F_2$ property evaluation as MIM, MIS device fabrication. Ca $F_2$ films were deposited at the various substrate temperature using a thermal evaporation. Ca $F_2$ films was grown as polycrystalline film and showed grain size variation as a function of substrate temperature and RTA post-annealing treatment. C-V, I-V results exhibit almost low $D_{it}$(1.8$\times$10$^{11}$ $cm^{-1}$ /le $V^{-1}$ ) and higher $E_{br}$ (>0.87MV/cm) than reported that formerly. Structural analysis indicate that low $D_{it}$ and high $E_{br}$ were caused by low lattice mismatch(6%) and crystal growth direction. Ca $F_2$ as a gate insulator of TFT are presented in this paper paperaper

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.2
• /
• pp.387-395
• /
• 2013

It is important to collect reliable measured data for proper bridge health monitoring. However, in reality incomplete and unreliable data may be acquired due to sensor problems and environmental effects. In case of sensor malfunction, parts of measured data are missing and thus health monitoring cannot be carried out reliably. Due to environmental effects such as temperature variation, dynamic characteristics of natural frequencies may change as if the structure is damaged. The paper proposes a systematic procedure of data processing and data analysis for reliable structural health monitoring. Also, it applies the Mahalanobis distance as a health index computed statistically using revised data. The proposed procedure has been examined using numerically simulated data from a truss structure and then applied to a set of field data measured from Seohae cable-stayed bridge.

• Wind and Structures
• /
• v.23 no.1
• /
• pp.1-18
• /
• 2016

This work experimentally and numerically analyzes the flow configurations and the dynamic wind loads on panels of rectangular L/h 5:1 cross section mounted on a structural frame of rectangular bars of L/h 0.5:1, corresponding to a radar structure. The fluid dynamic interaction between panels and frame wakes imposes dynamic loads on the panels, with particular frequencies and Strouhal numbers, different from those of isolated elements. The numerical scheme is validated by comparison with mean forces and velocity spectra of a panel wake obtained by wind tunnel tests. The flow configuration is analyzed through images of the numerical simulations. For a large number of panels, as in the radar array, their wakes couple in either phase or counter-phase configurations, changing the resultant forces on each panel. Instantaneous normal and tangential force coefficients are reported; their spectra show two distinct peaks, caused by the interaction of the wakes. Finally, a scaled model of a rectangular structure comprised of panels and frame elements is tested in the boundary layer wind tunnel in order to determine the influence of the velocity variation with height and the three-dimensionality of the bulk flow around the structure. Results show that the unsteady aerodynamic loads, being strongly influenced by the vortex shedding of the supporting elements and by the global 3-D geometry of the array, differ considerably on a panel in this array from loads acting on an isolated panel, not only in magnitude, but also in frequency.