• International Journal of Fluid Machinery and Systems
• /
• 제8권3호
• /
• pp.209-219
• /
• 2015

A robust multi-fidelity optimization methodology has been developed, focusing on efficiently handling industrial runner design of hydraulic Francis turbines. The computational task is split between low- and high-fidelity phases in order to properly balance the CFD cost and required accuracy in different design stages. In the low-fidelity phase, a physics-based surrogate optimization loop manages a large number of iterative optimization evaluations. Two derivative-free optimization methods use an inviscid flow solver as a physics-based surrogate to obtain the main characteristics of a good design in a relatively fast iterative process. The case study of a runner design for a low-head Francis turbine indicates advantages of integrating two derivative-free optimization algorithms with different local- and global search capabilities.

• 한국군사과학기술학회지
• /
• 제26권2호
• /
• pp.149-158
• /
• 2023

To predict the aerodynamic characteristics of the grid fins from subsonic to supersonic speeds, low fidelity SW as well as CFD SW were applied. VLM(Vortex Lattice Method) and SE(Shock-Expansion) method were used at subsonic and supersonic speed domain respectively for the rapid prediction of low fidelity SW. For 2 configurations of the grid fins, the CFD computations and tests using the trisonic wind tunnel were also performed to compare the results of the grid fins. The results of low fidelity SW, CFD SW and the wind tunnel tests data were agreed well each other. Through further research on the grid fins, the effective parameters of the grid fin configurations according to the speed regime will be investigated.

• 한국시뮬레이션학회:학술대회논문집
• /
• 한국시뮬레이션학회 2001년도 The Seoul International Simulation Conference
• /
• pp.131-135
• /
• 2001

A method for modeling and simulation of a satellite system is presented. The characteristics of a typical satellite system is discussed. for high fidelity modeling and simulator development of a satellite, the object-oriented analysis and design methodology is discussed and applied.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제7권4호
• /
• pp.247-253
• /
• 2007

In this paper, a high throughput multiple transform architecture for H.264 Fidelity Range Extensions (FRExt) is proposed. New techniques are adopted which (1) regularize the $8{\times}8$ integer forward and inverse DCT transform matrices, (2) divide them into four $4{\times}4$ sub-matrices so that simple fast butterfly algorithm can be used, (3) because of the similarity of the sub-matrices, mixed butterflies are proposed that all the sub-matrices of $8{\times}8$ and matrices of $4{\times}4$ forward DCT (FDCT), inverse DCT (IDCT) and Hadamard transform can be merged together. Based on these techniques, a hardware architecture is realized which can achieve throughput of 1.488Gpixel/s when processing either $4{\times}4\;or\;8{\times}8$ transform. With such high throughput, the design can satisfy the critical requirement of the real-time multi-transform processing of High Definition (HD) applications such as High Definition DVD (HD-DVD) ($1920{\times}1080@60Hz$) in H.264/AVC FRExt. This work has been synthesized using Rohm 0.18um library. The design can work on a frequency of 93MHz and throughput of 1.488Gpixel/s with a cost of 56440 gates.

• 한국항공우주학회지
• /
• 제36권1호
• /
• pp.31-38
• /
• 2008

본 논문은 헬리콥터 기동비행문제를 비선형 최적제어기법으로 정식화 하고 이를 indirect method를 적용하여 해석하는 기법에 대한 연구결과이다. 주어진 기동비행 경로에 대한 오차를 벌칙함수 형태의 가격함수로 채택하고 이를 최소화하도록 정식화하면 기동비행은 구속조건이 없는 최적제어문제로 정식화 된다. 정식화 결과로 얻어지는 이점 경계값 문제는 Multiple Shooting Method (MSM)를 적용하여 해석하였다. 본 논문은 high fidelity 헬리콥터 모델링을 적용할 경우 수치해의 불안정성과 과도한 계산시간에 따른 해석의 어려움을 해소하는 방안을 찾는데 초점을 두고 있다. 이를 위해 2가지의 선형모델과 로터의 비선형 모델링을 포함한 2개의 비선형 모델을 정의하였다. 각 모델링 방법의 적용에 따른 수치해석결과를 상대적인 계산시간과 함수계산 횟수 등을 비교하여 헬리콥터 모델 선정 시 활용할 수 있도록 하였다.

• Archives of Plastic Surgery
• /
• 제50권6호
• /
• pp.621-626
• /
• 2023

In the first half of the third century B.C., Herophilus and Erasistratus performed the first systematic dissection of the human body. For subsequent centuries, these cadaveric dissections were key to the advancement of anatomical knowledge and surgical techniques. To this day, despite various instructional methods, cadaver dissection remained the best way for surgical training. To improve the quality of education and research through cadaveric dissection, our institution has developed a unique method of perforator-preserving cadaver injection, allowing us to achieve high-fidelity perforator visualization for dissection studies, at low cost and high efficacy. Ten full body cadavers were sectioned through the base of neck, bilateral shoulder, and hip joints. The key was to dissect multiple perfusing arteries and draining veins for each section, to increase "capture" of vascular territories. The vessels were carefully flushed, insufflated, and then filled with latex dye. Our injection dye comprised of liquid latex, formalin, and acrylic paint in the ratio of 1:2:1. Different endpoints were used to assess adequacy of injection, such as reconstitution of eyeball volume, skin turgor, visible dye in subcutaneous veins, and seepage of dye through stab incisions in digital pulps. Dissections demonstrated the effectiveness of the dye, outlining even the small osseous perforators of the medial femoral condyle flap and subconjunctival plexuses. Our technique emphasized atraumatic preparation, recreation of luminal space through insufflation, and finally careful injection of latex dye with adequate curing. This has allowed high-fidelity perforator visualization for dissection studies.

• 한국정보통신학회논문지
• /
• 제14권2호
• /
• pp.462-468
• /
• 2010

본 논문에서는 기존의 full color LED 전광판 영상 처리 방식을 개선시킨 획기적인 영상 구동 처리 기술을 제안하였다. 이 기술은 고화질의 대형 TV나 LCD Display에 적용 가능하며 선명한 표출구동의 영상제어를 가능하게 한다. 제안한 구동 제어 방식은 기존의 영상처리 기능을 효율적으로 보강할 수 있다. 자동 또는 수동으로 contrast, bright, tint, color, 감마보정 등의 영상 변화처리 조절이 가능하므로 선명한 화질을 얻을 수 있다. 그리고 경제적인 가격으로 구현이 가능하다.

• 한국간호교육학회지
• /
• 제23권3호
• /
• pp.319-329
• /
• 2017

Purpose: This study evaluated the acquisition and retention effects on diabetes knowledge and academic self-efficacy of patient simulation-based hypoglycemia scenario using a high-fidelity simulator. Methods: A nonequivalent control group pretest/posttest repeated measures quasi-experimental design determined if nursing simulation using a high-fidelity simulator helps students acquire and retain diabetes knowledge and academic self-efficacy. A total of 101 nursing students from two universities participated in this study, comprising the experimental and control groups. The experimental group (n=52) at a university in S city comprised participants in an adult nursing class, nursing practicum, and simulation education. The control group (n=49) at a university in C city participated in an adult nursing class and nursing practicum without simulation education. Results: The experimental group had statistically significant group-time interaction effects on diabetes knowledge (p=.044) and self-confidence (p<.001) of academic self-efficacy compared to the control group. Conclusion: The results indicated that the patient simulation-based hypoglycemia scenario using a high-fidelity simulator applied to nursing education is useful in encouraging nursing students to engage in strategies with acquisition and retention effects, enhancing their diabetes knowledge and self-confidence of academic self-efficacy. Therefore, educators should use simulation programs effectively with nursing classes and practicum to enhance the effects of nursing competencies.

• 한국정보통신설비학회:학술대회논문집
• /
• 한국정보통신설비학회 2007년도 학술대회
• /
• pp.350-353
• /
• 2007

This paper presents an real-time implementation of H.264/AVC High 4:4:4 Predictive profile decoder using general-purpose processors by exploiting multi-threading technique and Single Instruction Multiple Data (SIMD) instructions without any quality degradation. We analyze differences between the existing High profile and High 4:4:4 Predictive profile decoder, and show various optimization techniques to decode high fidelity and high definition (HD) video in real-time. Simulation results show that the proposed decoder can play high fidelity HD video at average 40 frames per seconds (fps) for the IBBrBP bistream and about 50 fps for the Intra-only bitstream.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제54권5호
• /
• pp.327-329
• /
• 2005

Conventional CDDA(Compact Disc Digital Audio) system has limitation which means that bandwidth and resolution of the sign릴 are determined by the sampling frequency and quantization bit, 44.1kHz and 16 bit respectively. Though, new medium such as DVD-audio is developed for high-resolution audio recording, it has high complexity and difficulty in manufacturing process. So, CDDA is a widely used medium for high fidelity audio yet. In this paper, we design a new encoding system for high-resolution audio signal which has backward compatible with conventional CDDA. By evaluating for the encoding and decoding process. we verify the availability of our proposed system.