• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.9-16
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• 2004

Performing adjustments where the observation equations involve more than a single measurement are General Least Squares(GLS) and Total Least Squares(TLS). This paper introduces theory of the GLS and TLS and compared experimentally accuracy and efficiency of those through 2D conformal coordinate transformation and 2D affine coordinate transformation. In conclusion, in case of 2D coordinate transformation, GLS can produce a little more accurate and efficient than TLS. In survey fields, The GLS and TLS can be used cooperatively for adjusting the actual coordinate measurements.

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.473-478
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• 2002

Circular slab waveguides are conformally mapped into straight waveguides. In the outer cladding region with monotonically increasing index profile, modified Airy functions (MAF) of traveling-wave form are introduced to express the leaky mode. Field distributions and losses calculated by the proposed method are compared with those obtained by the WKB (Wentzel-Kramers-Brillouin) method. Detailed numerical examples are presented and compared with the conventional WKB methods, demonstrating our method not only allows a converging field at turning points but also guarantees fine accuracy.

• Current Optics and Photonics
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• v.1 no.4
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• pp.336-343
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• 2017

A wide field-of-view (FOV) image contains more visual information than a conventional image. This study proposes a new type of hyperbolic mirror for wide FOV image acquisition. The proposed mirror consists of a hyperbolic cylindrical section and a bowl-shaped hyperbolic omnidirectional section. Using an imaging system with this mirror, it is possible to achieve a $213.8^{\circ}$ horizontal and a $126.94^{\circ}$ vertical maximum FOV. Parameters of each section of the mirror are designed to be continuous at the junction of the two parts, and the resultant image is seamless. The image-acquisition model is obtained using ray-tracing optics. To rectify the geometrical distortion of the original image due to the mirror, an image-restoration algorithm based on conformal projection is presented in this study. The performance of the proposed imaging system with the hyperbolic mirror and its image-restoration algorithm are verified by experiments.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.1
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• pp.25-40
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• 2015

Understanding the effects of the parameters affecting the interaction of tandem hydrofoil system is a crucial subject in order to fully comprehend the aero/hydrodynamics of any vehicle moving inside a fluid. This study covers a parametric study on tandem hydrofoil interaction in both potential and viscous fluids using iterative Boundary Element Method (BEM) and RANSE. BEM allows a quick estimation of the flow around bodies and may be used for practical purposes to assess the interaction inside the fluid. The produced results are verified by conformal mapping and Finite Volume Method (FVM). RANSE is used for viscous flow conditions to assess the effects of viscosity compared to the inviscid solutions proposed by BEM. Six different parameters are investigated and they are the effects of distance, thickness, angle of attack, chord length, aspect ratio and tapered wings. A generalized 2-D code is developed implementing the iterative procedure and is adapted to generate results. Effects of free surface and cavitation are ignored. It is believed that the present work will provide insight into the parametric interference between hydrofoils inside the fluid.

• Journal of Powder Materials
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• v.25 no.1
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• pp.60-68
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• 2018

The design and fabrication of photoelectrochemical (PEC) electrodes for efficient water splitting is important for developing a sustainable hydrogen evolution system. Among various development approaches for PEC electrodes, the chemical vapor deposition method of atomic layer deposition (ALD), based on self-limiting surface reactions, has attracted attention because it allows precise thickness and composition control as well as conformal coating on various substrates. In this study, recent research progress in improving PEC performance using ALD coating methods is discussed, including 3D and heterojunction-structured PEC electrodes, ALD coatings of noble metals, and the use of sulfide materials as co-catalysts. The enhanced long-term stability of PEC cells by ALD-deposited protecting layers is also reviewed. ALD provides multiple routes to develop improved hydrogen evolution PEC cells.

• Bulletin of the Society of Naval Architects of Korea
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• v.14 no.2
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• pp.1-9
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• 1977

Streamlines around a ship's hull can be calculated by using streamline tracing method replacing the ship section with distribution of singularity. The influence of frame lines on the stream surrounding a hull surface, however, can not be found. Jinnaka studied on streamlines for Lewis form by applying the slender body theory. The influence of frame lines on stream surrounding a hull surface is well found in Jinnaka's method. In this paper streamline calculation method for chine type has been developed by using conformal transformation and applying slender body theory as Jinnaka did. Three kinds of model-one of series 62 for chine type, V.L.C.C. and high speed craft built in Korea for Lewis form-were used for streamline calculation;

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.282-285
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• 1999

Fabrication and pakaging method for low delve voltage and 10Gbps Ti diffused waveguide LiNbO$_3$ optical intensity modulator are described. Optical waveguides were prepared by conventionaly electron-beam evaporation and Ti-indiffusion into Z-cut plate LiNbO$_3$. Traveling-wave electrodes were used for obtaining the wideband frequency response and impedance matching. Microwave effective index and characteristic impedance measured by time domain reflectometry and compared with the calculated value by conformal mapping. The characteristics of 10Gbps modulator at the 1550nm wavelength are as follows : perfect modulation voltage Is about 5V, optical insertion loss Is about 5dB, 3-dB bandwidth is 10GHz, and characteristic impedance is about 50$\Omega$.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.67-69
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• 1998

In order to design or predict the performance of a cylindrical electrostatic motor it is necessary to analyze the torque generated by such a structure. In this paper a simple but sufficiently accurate analytical model is developed for use in design. Conformal mapping are used to model the capacitance and torque of the motor as a function of the rotor position, using a quasi-static, two-dimension approximation, the effect of an insulating dielectric layer on the stator or rotor is also evaluated.

• Bulletin of the Society of Naval Architects of Korea
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• v.18 no.4
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• pp.13-20
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• 1981

The hydrodynamic added mass of two dimensional cylinders oscillating vertically at high frequencies in the free surface is of interest to ship vibration problems. Conformal transformation is one of the methods commonly in use for computing the inertia coefficient. Especially, Schwarz-Christoffel transformation has been employed to evaluate the inertia coefficient for the cylinders of straight frames and chines. In this paper, the inertia coefficient for the cylinders with round corners in vertical oscillation at high frequencies are evaluated by employing the Schwarz-Christoffel transformation for the concave corner. The results of calculation by employing the Schwarz-Christoffel transformation are found to be well within the expected range of values compared to Lewis form and the results obtained by source distribution method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.11
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• pp.25-31
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• 1990

We analyze the spherical-rectangular patch microstrip resonator with conformal surface by the cavity model and derive the formulas to calculate resonant frequency in the consideration of effective dielectric constant in order to minimize the errors of resonant frequency due to the fringing fields. A transmission type spherical-rectangular patch microstrip resonator operating at 3GHz, for example, is designed and fabricated on Epsilam-10 substate. Measuring data of resonant frequency and return loss are 2.985 GHz and -44.4dB respectively. Those well agreed with theoretical values.