• Wind and Structures
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• v.7 no.6
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• pp.359-372
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• 2004

Wind tunnel model studies were carried out to determine the wind load distribution on tributary areas near the gable-end of large, low-rise buildings with high pitch planar and curved roof shapes. Background pressure fluctuations on each tributary area are described by a series of uncorrelated modes given by the eigenvectors of the force covariance matrix. Analysis of eigenvalues shows that the dominant first mode contributes around 40% to the fluctuating pressures, and the eigenvector mode-shape generally follows the mean pressure distribution. The first mode contributes significantly to the fluctuating load effect, when its influence line is similar to the mode-shape. For such cases, the effective static pressure distribution closely follows the mean pressure distribution on the tributary area, and the quasi-static method would provide a good estimate of peak load effects.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.893-895
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• 2013

In this paper, we propose the planar folded monopole antenna with an inverted T-shape notch in ground plane. The proposed antenna is not only varied to a width of inner and outer patch lines to broaden bandwidth, but also it is inserted to a modified inverted T-shape notch with the same length of horizontal and vertical slit, difference of its width is about twice in the ground plane to broaden bandwidth. It is designed and simulated.

• Journal of the Korea Computer Graphics Society
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• v.18 no.4
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• pp.1-8
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• 2012

We present improved deformation energy to enhance the visual quality of a shape deformation technique, where we preserve the local structure of an input planar shape. The deformation energy, in general, consists of several constraints such as Laplacian coordinate constraint to preserve the quality of deformed silhouette edges, mean value coordinates and edge length constraints to preserve the quality of deformed internal shape, and user-specified position constraints to control the shape deformation. When the positions of user-specified vertices change, shape deformation techniques compute the positions of the other vertices by means of nonlinear least squares optimization to minimize the deformation energy. When a user-specified vertex changes its position rapidly, it is frequently observed that the visual quality of the deformed shape decrease rapidly, which is mainly caused by unnecessary enlargement of the Laplacian vectors and unnecessary change of the edge directions along the boundary of the shape. In this paper, we propose improved deformation energy by prohibiting the Laplacian and edge length constraints from changing unnecessarily. The proposed deformation energy incorporated with well-known optimization technique can enhance the visual quality of shape deformation along the silhouette and within the interior of the planar shape while sacrificing only a little execution time.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.237-238
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• 2013

• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.518-523
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• 1999

In thi, study, we made experiments to fonn a mesa shape by meltback method with various concentration of solutions and found that unsaturated (20%) InGaAsP (1.55 !-tm) solution at a growth temperature was the most suitable for the formation of a mesa ,hape on the wafer which has an InGaAsP active layer and an InP cap layer on an n-InP substrate. It was difficult to form a proper mesa shape for the fabrication of PBH-LDs only by the meltback method; therefore, we fabricated PBH-LDs by forming the mesa shape with the meltback method after wet etching and by growing a current-blocking layer successively. As the electrical and optical charaleri,tiecs of MQW-PBH-LDs fabricated by above methods, when the cavity length was $300{\mu}m$, the threshold current was about 10 mA, internal quantum efficiency 82%, internal loss $9.2cm^{-1}$, and characteristic temperature was 65 K at $25~45^{\circ}C$ and 42 K at $45~65^{\circ}C$. /TEX>.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.812-817
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• 2008

A catalytic combustible sensor for LPG/LNG detection was fabricated on $Al_2O_3$ substrate using planar technology. The catalysts of Pd and Pt were added to ${\alpha}$- and ${\gamma}-Al_2O_3$ powders. The mixture of Pt, Pd and $Al_2O_3$ were homogenized by using a three roll mixer. TCR characteristics of Pt heater were optimized with the heat treatment temperature. Sensing properties were investigated as a function of the microstructure of $Al_2O_3$, the gas concentration and the variation of input voltage. ${\alpha}-Al_2O_3$ sintered at 500 $^{\circ}C$ is more suitable as LPG/LNG sensor due to good grain shape and size distribution of about 300 nm than that of ${\gamma}-Al_2O_3$ which is in irregular shape and with a particle size of 5-30 ${\mu}m$. The sensor has shown maximum output voltage of 14 mV for 1000 ppm $C_4H_{10}$ and 3.8 mV for 1000 ppm $CH_4$ at 5.0 V input voltage.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.1 no.3
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• pp.3-8
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• 2008

In this paper, an planar antenna which has omnidirectional radiation pattern in H-plane and low profile is proposed. By adding inductance elements of an ENG shell structure, a capacitance element of an electrically small antenna is easily achieved with impedance matching. An ENG shell structure is consist of a inductive loading structure which has symmetrical four stepped L-shape slots. The simulated result shows, the impedance bandwidth of the proposed antenna is 150MHz (2.5 ~ 2.65GHz). The simulated maximum radiation gain of proposed antenna is 1.12 dBi at center frequency 2.56GHz. Omnidirectional radiation pattern is achieved. The proposed antenna will be applied to wireless lan access point system.

• Journal of Korean Association for Spatial Structures
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• v.21 no.4
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• pp.23-30
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• 2021

In this paper, a twisted shape structure with an elevation form favorable to the resistance of vibration caused by wind loads is selected from among the forms of high-rise buildings. The analytical model is a square, triangular, and hexagonal plane with a plane rotation angle of one degree from 0 to 3 degrees per each story. As a result of the analysis, as the twist angle increased, story drift ratio is increased. Responses with different eccentricity rates were shown by analytical models. Therefore planar shapes designed symmetrically to the horizontal axis of X and Y are considered advantageous for eccentricity and torsion deformation. In the case of the bending moment of the column, the response was amplified in the column supporting the base floor, the roof floor, the floor in which the cross-section of the vertical member changes, and the floor having the same number of nodes as the base floor. Finally, the axial force response of the column is determined to be absolutely affected by the gravity load compared to the lateral load.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.267-272
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• 1998

A new signal processing technique, the directional harmonic wavelet map(dHWM), is presented to characterize the instantaneous planar motion of a measurement point in a structure from its transient complex-valued vibration signal. It is proven that the auto-dHWM essentially tracks the shape and directivity of the instantaneous planar motion, whereas the phase of the cross-dHWM indicates its inclination angle. Finally, the technique is successfully applied to an automobile engine for characterization of its transient motion during crank-on/idline/engine-off.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.250-254
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• 2002

In this paper, we design an optimized planar array structure with triangular lattice for side-lobe reduction using a genetic algorithm. A constraint optimization is implemented by optimally removing some outer array elements far from the array center. It is shown that only the proper array shape without optimizing the magnitudes and phases of each array antenna can give low side-lobe level with a slight main beam broadening.