• 한국전자파학회논문지
• /
• 제18권4호
• /
• pp.372-378
• /
• 2007

본 논문에서는 Schroeder 방식의 QRD(Quadratic Residue Diffuser)를 사용하여 전자파 잔향실 내부의 필드 균일도를 향상시키고, 전자파 잔향실 내벽 전체 면적 대비 QRD가 차지하는 면적비를 변화시키면서 필드 균일도를 향상시키는 최적의 면적비에 대하여 연구하였다. $1{\sim}3\;GHz$의 주파수 대역에서 QRD를 설계하였고, 전자파 잔향실의 전계 특성 및 필드 균일도 향상을 조사하기 위해 FDTD(Finite-Difference Time-Domain) 방법의 수치 해석이 이루어졌다. 2 GHz에서 QRD 크기가 잔향실 한쪽 내벽의 약 $30{\sim}60\;%$일 경우 표준 편차가 가장 작았으며, 20 % 이하, 70 % 이상에서는 점차로 필드 균일도가 나빠짐을 알 수 있었다. 특히 QRD의 면적이 30 %일 때와 적용되지 않은 경우를 비교한 결과, 전자의 경우 표준 편차가 후자의 경우에 비하여 1.53 dB가 향상되는 것을 확인하였다.

• 한국전산응용수학회:학술대회논문집
• /
• 한국전산응용수학회 2003년도 KSCAM 학술발표회 프로그램 및 초록집
• /
• pp.1-1
• /
• 2003

In this talk, a reduced-order modeling methodology based on centroidal Voronoi tessellations (CVT's)is introduced. CVT's are special Voronoi tessellations for which the generators of the Voronoi diagram are also the centers of mass (means) of the corresponding Voronoi cells. The discrete data sets, CVT's are closely related to the h-means clustering techniques. Even with the use of good mesh generators, discretization schemes, and solution algorithms, the computational simulation of complex, turbulent, or chaotic systems still remains a formidable endeavor. For example, typical finite element codes may require many thousands of degrees of freedom for the accurate simulation of fluid flows. The situation is even worse for optimization problems for which multiple solutions of the complex state system are usually required or in feedback control problems for which real-time solutions of the complex state system are needed. There hava been many studies devoted to the development, testing, and use of reduced-order models for complex systems such as unsteady fluid flows. The types of reduced-ordered models that we study are those attempt to determine accurate approximate solutions of a complex system using very few degrees of freedom. To do so, such models have to use basis functions that are in some way intimately connected to the problem being approximated. Once a very low-dimensional reduced basis has been determined, one can employ it to solve the complex system by applying, e.g., a Galerkin method. In general, reduced bases are globally supported so that the discrete systems are dense; however, if the reduced basis is of very low dimension, one does not care about the lack of sparsity in the discrete system. A discussion of reduced-ordering modeling for complex systems such as fluid flows is given to provide a context for the application of reduced-order bases. Then, detailed descriptions of CVT-based reduced-order bases and how they can be constructed of complex systems are given. Subsequently, some concrete incompressible flow examples are used to illustrate the construction and use of CVT-based reduced-order bases. The CVT-based reduced-order modeling methodology is shown to be effective for these examples and is also shown to be inexpensive to apply compared to other reduced-order methods.

• 대한토목학회논문집
• /
• 제8권1호
• /
• pp.165-172
• /
• 1988

도로망(道路網)의 신설(新設) 및 개량사업(改良事業)의 적정화(適正化)를 위하여, 연속적(連續的) 설계변수(設計變數)를 채택(採擇)한 가로망(街路網) 설계기법(設計技法)을 제시(提示)하였다. 이를 위하여 수정(修正)된 Hooke-and-Jeeves 알고리듬을 사용(使用)함으로써, 통행시간(通行時間) 및 통행비용(通行費用)과 도로건설비용(道路建設費用)의 합(合)으로 구성(構成)되는 가로망(街路網) 설계문제(設計問題)의 해(解)를 풀었다. 여러 가지 형태(形態)의 건설비용함수(建設費用凾數)와 초기해(初期解)의 위치(位置), 도로구간별(道路區間別) 개선정도(改善程度)의 초기치별(初期値別)로 이 기법(技法)의 적용도(適用度)를 검토(檢討)하였다. 본(本) 논문(論文)의 연구결과(硏究結果), 가로망(街路網) 설계(設計)의 평가회수(評價回數)를 크게 줄였으며, 효율적(効率的)인 초기해(初期解), 초기용량증감치(初期容量增減値), 근사기법(近似技法) 등이 제시(提示)되었다.

• 패션비즈니스
• /
• 제20권3호
• /
• pp.17-29
• /
• 2016

To develop baseball catcher leg guards, 3-dimensional (3D) methodologies, which are 3D human body data, reverse engineering, modeling, and printing, optimized guard design for representative positions. Optimization was based on analysis of 3D body surface data and subjective evaluation using 3D printing products. Reverse engineering was used for analysis and modeling based on data in three postures: standing, $90^{\circ}$ knee flexion, and $120^{\circ}$ knee flexion. During knee flexion, vertical skin length increased, with the thigh and knee larger in anterior area compared to the horizontal dimension. Moreover, $120^{\circ}$ knee flexion posture had a high radius of curvature in knee movement. Therefore, guard designs were based on increasing rates of skin deformation and numerical values of radius of curvature. Guards were designed with 3-part zoning at the thigh, knee, and shin. Guards 1 and 2 had thigh and knee boundaries allowing vertical skin length deformation because the shape of thigh and knee significantly affects to its performance. Guard 2 was designed with a narrower thigh and wider knee area than guard 1. The guards were manufactured as full-scale products on a 3D printer. Both guards fit better in sitting than standing position, and guard 2 received better evaluations than guard 1. Additional modifications were made and an optimized version (guard 3) was tested. Guard 3 showed the best fit. A design approach based on 3D data effectively determines best fitting leg guards, and 3D printing technology can customize guard design through immediate feedback from a customer.

• 전기학회논문지
• /
• 제66권9호
• /
• pp.1392-1401
• /
• 2017

In this study, the design methodology of pattern classification is introduced for avoiding faults through partial discharge occurring in the power facilities and local sites. In order to classify some partial discharge types according to the characteristics of each feature, the model is constructed by using the Radial Basis Function Neural Networks(RBFNNs) and Particle Swarm Optimization(PSO). In the input layer of the RBFNNs, the feature vector is searched and the dimension is reduced through Principal Component Analysis(PCA) and PSO. In the hidden layer, the fuzzy coefficients of the fuzzy clustering method(FCM) are tuned using PSO. Raw datasets for partial discharge are obtained through the Motor Insulation Monitoring System(MIMS) instrument using an Epoxy Mica Coupling(EMC) sensor. The preprocessed datasets for partial discharge are acquired through the Phase Resolved Partial Discharge Analysis(PRPDA) preprocessing algorithm to obtain partial discharge types such as void, corona, surface, and slot discharges. Also, when the amplitude size is considered as two types of both the maximum value and the average value in the process for extracting the preprocessed datasets, two different kinds of feature datasets are produced. In this study, the classification ratio between the proposed RBFNNs model and other classifiers is shown by using the two different kinds of feature datasets, and also we demonstrate the proposed model shows superiority from the viewpoint of classification performance.

• 한국의류산업학회지
• /
• 제20권4호
• /
• pp.464-473
• /
• 2018

The objective of this study is to develop a sizing system of fitness clothing that can properly accommodate various body sizes of Korean senior women. The sizing system of upper and lower fitness clothing was developed in the present study by selection of key variables, identification of size category candidates, and determination of an optimal sizing system. First, key anthropometric dimensions (stature and bust circumference for upper clothing and stature; waist circumference for lower clothing) were identified by factor analysis on the direct body measurements (n = 272) and 3D whole-body scan data (n = 271) of Korean senior women in Size Korea. Second, sizing system candidates based on the key dimensions of upper and lower clothing were explored using a grid method and an optimization method. Lastly, among the sizing system candidates, optimal sizing systems of upper and lower clothing were selected in terms of accommodation rate. Five size categories (short/small, short/medium, tall/small, tall/medium, and tall/large) were selected as the optimal sizing systems of upper and lower clothing with 89% and 78% of accommodation rate, respectively, for the Korean senior women. The anthropometric characteristics of the representative humans of the optimal size categories would be of use in the design of fitness compressive wear for the better fit and effectiveness of exercise and health of Korean senior women.

• 한국의학물리학회:학술대회논문집
• /
• 한국의학물리학회 2002년도 Proceedings
• /
• pp.150-153
• /
• 2002

High dose rate (HDR) brachytherapy in the treatment of cervix carcinoma has become popular, because it eliminated many of the problems with conventional brachytherapy. In order to improve clinical effectiveness with HDR brachytherapy, dose calculation algorithm, optimization procedures, and image registrations should be verified by comparing the dose distributions from a planning computer and those from a humanoid phantom irradiated. Therefore, the humanoid phantom should be designed such that the dose distributions could be quantitatively evaluated by utilizing the dosimeters with high spatial resolution. Therefore, the small size of thermoluminescent dosimeter (TLD) chips with the dimension of 1/8" and film dosimetry with spatial resolution of <1mm used to measure the radiation dosages in the phantom. The humanoid phantom called a pelvic phantom is made of water and tissue-equivalent acrylic plates. In order to firmly hold the HDR applicators in the water phantom, the applicators are inserted into the grooves of the applicator supporters. The dose distributions around the applicators, such as Point A and B, can be measured by placing a series of TLD chips (TLD-to- TLD distance: 5mm) in three TLD holders, and placing three verification films in orthogonal planes.

• 전자공학회논문지SC
• /
• 제42권2호
• /
• pp.33-38
• /
• 2005

신체 내 혈당 변화량과 $^1H$ 원자핵의 스핀-격자 완화시간의 변화량이 관련 있음과 원자핵의 스핀-격자 완화시간을 측정하는 방법으로 자기공명흡수법이 제안된 바 있다. 자기공병흡수법에 의하여 신체 내 혈당 변화량을 감지하기 위해서는 검출 영역내 고수준의 자기장의 세기와 균일도의 확보가 필수적이다. 가정에서 손쉽게 혈당의 변화량을 측정할 수 있도록, 본 논문에서는 가정용으로 적합한 크기와 무게를 가지면서 요구되는 자기장의 세기와 균일도를 확보한 무혈혈당측정기를 디자인하였다. 여러 형상과 재질을 갖는 초기 모델들을 설계, 제작하였고, 검출 영역의 자기 특성을 비교하여 최종 재질을 결정하였다. 또한, 유한요소 해석모델을 구축하고 형상 최적화를 통하여 최종 모델을 선정하였다.

• 반도체디스플레이기술학회지
• /
• 제14권3호
• /
• pp.1-5
• /
• 2015

In photolithography process, resolution enhancement techniques such as optical proximity correction (OPC) and phase shift mask (PSM) have been applied to improve resolution. Especially, sub-resolution assist feature (SRAF) is one of the most important OPC to enhance image quality including depth of focus (DOF). However, imaging performance of the mask could be varied with the diffraction order amplitude changed by inserting SRAF. Therefore, in this study, we investigated the imaging properties and process margin of attenuated PSM with SRAF. Reflectivities of attenuated PSMs at 13.5 nm were 3, 6, 9% and simulation was performed by $PROLITH^{TM}$. As a result, aerial image properties and DOF as well as diffraction efficiency were improved by increasing the reflectivity of attenuated PSM. Additionally, printed critical dimension variations depending on SRAF width and space error were also reduced for attenuated PSM with high reflectivity. However, SRAF could be printed when reflectivity of attenuated PSM is high enough. In conclusion, optimization of reflectivity of attenuated PSM and SRAF to prevent side-lobe from being printed is needed to be considered.

• 한국광학회지
• /
• 제17권2호
• /
• pp.175-180
• /
• 2006

리튬나이오베이트 기판의 분극 반전 기술을 이용하여 5.5 GHz대역의 SSB(Single Sideband) 광변조기를 설계 및 제작하였다. 분극 반전을 통해 광이 인가받는 유효전계가 마흐젠더 두 도파로에서 $90^{\circ}$ 위상차를 갖도록 할 수 있었다. 제작된 광변조기는 5.8 GHz의 중심주파수로, 1.9 V DC 인가 시 약 33 dB의 USB 억제율을, -10.6 V 인가 시 약 25 dB의 LSB 억제율을 나타내었다. 또한 2.5 GHz의 대역폭에서 15 dB 이하의 Sideband 억제율을 보이고 있다.