• 한국전산유체공학회:학술대회논문집
• /
• 2009.11a
• /
• pp.193-200
• /
• 2009

Recently, there have been efforts to construct hybrids among the existing methodologies for multiphase flow such as VOF, Level Set, and Front Tracking with the intention of facilitating simulations of general three-dimensional problems. As one of the hybrid method, we have developed the Level Contour Reconstruction Method (LCRM) for general three-dimensional multiphase flows including phase change. The main idea was focused on simplicity and a robust algorithm especially for the three-dimensional case. It combines characteristics of both Front Tracking and Level Set methods. While retaining an explicitly tracked interface using interfacial elements, the calculation of a vector distance function plays a crucial role in the periodic reconstruction of the interface elements in the LCRM method to maintain excellent mass conservation and interface fidelity. In addition, compact curvature formulation is incorporated for the calculation of the surface tension force thereby reducing parasitic currents to a negligible level.

• Current Optics and Photonics
• /
• v.7 no.6
• /
• pp.692-700
• /
• 2023

We present a method for improving the accuracy of the modal wavefront reconstruction in the radial shearing interferometers (RSIs). Our approach involves expanding the reduced radial terms of Zernike polynomials to high-order, which enables more precise reconstruction of the wavefront aberrations with high-spatial frequency. We expanded the reduced polynomials up to infinite order with symbolic variables of the radius, shearing amount, and transformation matrix elements. For the simulation of the modal wavefront reconstruction, we generated a target wavefront subsequently, magnified and measured wavefronts were generated. To validate the effectiveness of the high-order Zernike polynomials, we applied both low- and high-order polynomials to the wavefront reconstruction process. Consequently, the peak-to-valley (PV) and RMS errors notably decreased with values of 0.011λ and 0.001λ, respectively, as the order of the radial Zernike polynomial increased.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.2
• /
• pp.720-726
• /
• 2010

Haplotype-based research has become increasingly important in the field of personalized medicine since the haplotype reflects a set of SNPs (Single Nucleotide Polymorphisms) that are genetically associated and inherited together. Currently, the most widely used application softwares available for haplotype reconstruction, based on in silico method, include PL-EM, Haplotyper, PHASE and HAP. PL-EM, Haplotyper and PHASE are command-line application running on LINUX or Unix system and HAP is a web-based client-server application. This paper deals with an integrated haplotype reconstruction system that have been developed with PL-EM and Haplotyper selected from the accuracy test with experimentally verified data on public application softwares. This integrated system is a kind of client-sever one with user friendly web interface and can provide end-users with a high quality of haplotype analysis. SNPs genotype data with a length of 5 derived from 5 people and SNPs genotype data with a length of 13 derived from 15 people were used to test the analysis results of Haplotyper and PL-EM respectively. As a result, this system has been confirmed to provide the systematic and easy-to-understand analysis results that consist of two main parts, i.e. individual haplotype information and haplotype pool information. In this respect, the integration system will be utilized as a useful tool for the discovery of disease related genes and the development of personalized drugs through facilitating the reconstruction of haplotype maps.

• 유체기계공업학회:학술대회논문집
• /
• 2006.08a
• /
• pp.475-478
• /
• 2006

In electrical impedance tomography (EIT) an array of electrodes is attached on the boundary of an object and small alternating currents are injected through these electrodes, and then the resulting voltages are measured. An estimation for the cross-sectional resistivity distribution in the object is obtained by using these current and voltage data in a nondestructive manner. In this paper, the electrical impedance imaging of two-phase flows undergoing rapid transient is considered with a special emphasis on the effect of the current pattern on the image reconstruction. The trigonometric current pattern, which is commonly used in the conventional static electrical impedance imaging, shows poor performance in case of the dynamic imaging considered in this work. Extensive numerical experiments are conducted with various kinds of current patterns and their effects on the image reconstruction performance are examined.

• Journal of Power Electronics
• /
• v.16 no.5
• /
• pp.1791-1801
• /
• 2016

This paper considers a carrier based signal injection method for use in the three shunt sensing inverter (TSSI) for sensorless motor control. It also analyzes the loss according to the injection axis of the voltage signal. To remove both the phase current and rotor position sensors, a sensorless method and a phase current reconstruction method can be simultaneously considered. However, an interaction between the two methods can be incurred when both methods inject voltage signals simultaneously. In this paper, a signal injection based sensorless method with the 120° OFF Discontinuous PWM (DPWM) is implemented in a TSSI to avoid this interaction problem. Since one leg does not have a switching event for one sampling period in the 120° OFF DPWM, the switching loss is altered according to the injection axis. The switching loss in the d-axis injection case can be up to 32% larger than that in the q-axis injection case. Other losses according to the injection axis are also analyzed.

• Journal of the Optical Society of Korea
• /
• v.13 no.4
• /
• pp.451-455
• /
• 2009

We present a numerical procedure that compensates for tilt phase aberration in in-line digital holography by computing the period of interference patterns in the reconstructed phase image. This method enables the reconstruction of correct and accurate phase information, even if strong tilt aberrations exist. Example applications of tilt aberration compensation are shown for a tilted plate, a micro-lens array, and a thin film transistor. This method is convenient because it uses only one hologram and no hardware to minimize the tilt aberration.

• Journal of information and communication convergence engineering
• /
• v.21 no.1
• /
• pp.90-97
• /
• 2023

Digital holographic microscopy (DHM) is a three-dimensional (3D) imaging technique that uses the phase information of coherent light. In the reconstruction process of DHM, a narrow region around the positive or negative sideband from the Fourier domain is windowed to avoid noise due to the DC spectrum of the hologram spectrum. However, the limited size of the window also degrades the high-frequency information of the 3D object profile. Although a large window can have more detailed information of the 3D object shape, the noise is increased. To solve this trade-off, we propose phase difference averaging (PDA). The proposed method yields high-frequency information of the specimen while reducing the DC noise. In this paper, we explain the reconstruction algorithm for this method and compare it to various conventional filtering methods including Gaussian, Wiener, average, median, and bilateral filtering methods.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2008.05a
• /
• pp.165-167
• /
• 2008

We present the basic theory on phase filtering of hologram to improve the image quality on image reconstruction.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.04b
• /
• pp.313-315
• /
• 2004

SNP(Single Nucleotide Polymorphism)은 생물학적 다양성에 관한 연관성 연구(Association Study)에서 이용되어지고 있다. haplotype을 구하기 위해 genotype data를 Haplotype Reconstruction을 하여 한 가닥씩 분리를 한다. Haplotype Reconstruction의 방법은 생물학적 접근법(molecular method)과, 계산적 접근방법(in-silico method)으로 연구되고 있다 계산적 접근법은 생물학적 접근법에 비해 적은 비용과 시간이 소요되는 장점을 지니지만, phase problem으로 인하여 생물학적 접근법에 비해 정확도가 낮다는 단점을 갖는다. 이런 문제를 해결하기 위한 설러 알고리즘들과 프로그램들이 연구 및 개발되고 있다. 본 논문에서는 현재 개발된 프로그램들에 대해서 다양한 테스트를 통한 각 프로그램의 성능 비교를 하였고, 특성과 문제점을 파악하였다.

• Archives of Craniofacial Surgery
• /
• v.18 no.3
• /
• pp.149-154
• /
• 2017

Computer-aided surgery (CAS) started being used for head and neck reconstruction in the late 2000s. Its use represented a paradigm shift, changing the concept of head and neck reconstruction as well as mandible reconstruction. Reconstruction using CAS proceeds through 4 phases: planning, modeling, surgery, and evaluation. Thus, it can overcome a number of trial-and-error issues which may occur in the operative field and reduce surgical time. However, if it is used for oncologic surgery, it is difficult to evaluate tumor margins during tumor surgery, thereby restricting pre-surgical planning. Therefore, it is dangerous to predetermine the resection margins during the presurgical phase and the variability of the resection margins must be taken into consideration. However, it allows for the preparation of a prebending plate and planning of an osteotomy site before an operation, which are of great help. If the current problems are resolved, its applications can be greatly extended.