• 대한기계학회논문집A
• /
• 제35권12호
• /
• pp.1563-1571
• /
• 2011

본 연구에서는 인간중이의 소리전달특성 계산을 위한 유한요소모델을 개발하였다. 이소골의 형상을 얻기 위하여 한국인 사체에서 추출한 측두골을 마이크로 CT 촬영하여 3 차원 입체모델로 변환하였다. 유한요소모델은 이소골, 고막, 인대와 근육 등을 포함하여 구성하였다. 유한요소모델을 이용하여 고막에서 등골족판까지의 응답함수를 계산한 후 측정값을 갖는 선행연구와 비교하였고 그 결과 10 kHz 주파수 대역까지 소리전달특성을 잘 표현하고 있음을 보였다. 또한 유한요소 모델을 구성하는 주요 물성인자의 변화에 대한 소리전달특성의 변화를 살피고 침등골관절의 강성값이 중이의 소리전달특성에 큰 영향을 미침을 보였다.

• 대한기계학회논문집B
• /
• 제26권10호
• /
• pp.1427-1435
• /
• 2002

The main aim of the present article is numerically to investigate the micro-scale heat transfer phenomena in a silicon microstructure irradiated by picosecond-to-femtosecond ultra-short laser pulses. Carrier-lattice non-equilibrium phenomena are simulated with a self-consistent numerical model based on Boltzmann transport theory to obtain the spatial and temporal evolutions of the lattice temperature, the carrier number density and its temperature. Especially, an equilibration time, after which carrier and lattice are in equilibrium, is newly introduced to quantify the time duration of non-equilibrium state. Significant increase in carrier temperature is observed for a few picosecond pulse laser, while the lattice temperature rise is relatively small with decreasing laser pulse width. It is also found that the laser fluence significantly affects the N 3 decaying rate of Auger recombination, the carrier temperature exhibits two peaks as a function of time due to Auger heating as well as direct laser heating of the carriers, and finally both laser fluence and pulse width play an important role in controlling the duration time of non-equilibrium between carrier and lattice.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.283-291
• /
• 2011

수직발사 추진기관의 추력방향조종(TVC)용으로 사용되는 제트베인 조립체의 열전달 특성을 고찰하기 위해 수치해석을 수행하였다. 본 연구에서 제트베인 주위의 대류열전달계수는 열경계층 방정식의 해와 반실험식을 사용하여 구하였다. 제트베인 조립체의 3차원 온도분포에 대한 해석은 PATRAN과 ABAQUS 소프트웨어를 사용하여 수행되었다. 본 수치해석 기법의 타당성은 제트베인 축 내부에서 측정한 온도와 열해석 결과의 비교를 통해 검증하였다. 제트베인의 3개 편향각(0o, 12.5o, 25o)에 대해 연소시간별 제트베인의 온도변화를 고찰하였다.

• 대한인간공학회지
• /
• 제22권4호
• /
• pp.1-13
• /
• 2003

This study has investigated psychological responses to various TV advertisements by using EEG(electroencephalogram). In particular, it was assumed that the brain wave would show different patterns depending upon the style of the advertisement that could be categorized into two such as 'information transfer' type and 'emotional reaction' type. Ten healthy males participated in the experiment. EEG signal was extracted from six lobes such as right and left frontal, right and left occipital, right and left temporal while the subjects were watching TV advertisements. Alpha and beta relative power spectrum, and beta/alpha parameter were calculated to compare two kinds of advertisement each other. Additionally, subjective questionnaire was used to examine subject's response by using adjective words and preference test. In result, significant differences were found in left frontal and right occipital lobe in terms of beta/alpha between two different advertisements. And, subjects showed different preference between two advertisements. It was shown that the current method could analyze the brain reaction to advertisement quantitatively, that presented the possibility of using it to marketing research.

• The Journal of Korean Physical Therapy
• /
• 제12권1호
• /
• pp.163-172
• /
• 2000

The purpose of this study was to provide experimental evidence and theoretical background for the applicability of bilateral transfer paradigm to the rehabilitation programs for children with hemiplegic cerebral palsy. Children with hemiplegia, which means unilateral motor disabilities, display abnormal motor and postural patterns of the affected side due to hemiparesis, spasticity, and sensory disorders, resulting in a decreased motor abilities of the affected side compared to unaffected side. Accordingly, they tend to rely on the unaffected limb for everyday activities, which further deteriorates the functions of the affected side by causing associated reaction, abnormal postural patterns, and hypertonus. Rehabilitation programs developed for children with hemiplegic cerebral palsy include neurodevelopmental treatment, application of cast or splint to unaffected limb, neuromuscular electrical stimulation, and task oriented model. These programs, however, have several drawbacks, such as discontinuity in treatment effect and psychological hatred to the force use of the affected side. In order to solve these problems and enhance the efficiency of the rehabilitation programs, it is required to maximize the use of the affected side without hatred. Characteristics of the control system, such as temporal coupling and spatial assimilation between limbs and neural crosstalk at different levels of central motor pathway, suggest that the bilateral transfer paradigm may enhance the efficiency of the rehabilitation programs for children with hemiplegic cerebral palsy.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
• /
• pp.436-442
• /
• 2012

액체로켓 엔진의 제어 로직이나 제어 알고리즘을 설계하고 유량제어밸브의 작동 스킴을 결정하는데 있어서 엔진의 동특성을 파악하는 것은 무엇보다 중요한 일이다. 하지만 엔진의 동특성을 시험을 통해서 사전에 얻는 것은 상당히 어려운 일이기 때문에 해석적인 모델을 이용하는 경우가 많다. 이에 본 연구에서는 기존에 개발된 엔진의 정상상태 부근에서의 동특성 해석 모델을 이용하여 이러한 동특성 모델을 계산하였다. 해석 모델을 이용하여 외란을 가하여 얻어진 응답특성을 Levy 방법을 이용하여 엔진의 동특성 모델을 하나의 전달함수로 근사할 수 있음을 보였다.

• International Journal of Computer Science & Network Security
• /
• 제23권5호
• /
• pp.73-88
• /
• 2023

Brain tumors can also be an abnormal collection or accumulation of cells in the brain that can be life-threatening due to their ability to invade and metastasize to nearby tissues. Accurate diagnosis is critical to the success of treatment planning, and resonant imaging is the primary diagnostic imaging method used to diagnose brain tumors and their extent. Deep learning methods for computer vision applications have shown significant improvements in recent years, primarily due to the undeniable fact that there is a large amount of data on the market to teach models. Therefore, improvements within the model architecture perform better approximations in the monitored configuration. Tumor classification using these deep learning techniques has made great strides by providing reliable, annotated open data sets. Reduce computational effort and learn specific spatial and temporal relationships. This white paper describes transfer models such as the MobileNet model, VGG19 model, InceptionResNetV2 model, Inception model, and DenseNet201 model. The model uses three different optimizers, Adam, SGD, and RMSprop. Finally, the pre-trained MobileNet with RMSprop optimizer is the best model in this paper, with 0.995 accuracies, 0.99 sensitivity, and 1.00 specificity, while at the same time having the lowest computational cost.

• 한국통신학회논문지
• /
• 제29권1C호
• /
• pp.92-101
• /
• 2004

논문에서는 MPEG-4(Moving Picture Expert Group-4) 객체기반 부호화를 위하여 영상에서 실 시간적으로 변화영역(객체)을 추출하는 알고리즘에 대하여 제안한다. 기존의 객체 분리방법 들은 Off-Line 방법으로 객체를분리하므로 실시간 처리를 필요로 하는 영상전화나 영상회의 시스템에서는 사용할 수 없었다. 그리고 또 MPEG-4표준의 버전1에서 권장하는 객체분할 방식인 공간적인 분할(Spatial Segmentation)방법과 시간적인 분할(Temporal Segmentation)방법은 픽셀단위로 연산을 하므로 연산의 복잡도가 높아서 실시간 영상전송에 어렵다. 그러나 이 논문에서 제안하는 알고리즘은 연산단위를 픽셀단위로 연산하는 것이 아니라 매크로블록 단위로 연산이 이루어지므로 실시간 전송을 가능케 한다. 그러나MPEG-4권고 안에서 제시한 알고리즘처럼 이 번에 제안한 알고리즘도 한 영상에서 여러 개의 객체를 추출하는 것이 이루어지지 않았다. 그리고 전체 시스템 구성을 보면 크게 부호기와 복호기로 나누어지고 부호기에 본 논문에서 제안한 실시간 객체추출 알고리즘이 전처리 단으로 삽입되어 구현되었다.

• 설비공학논문집
• /
• 제28권8호
• /
• pp.305-310
• /
• 2016

A thermal storage systems was designed to correspond to the temporal or quantitative variation in the thermal energy demand, and most of its heat is stored using the latent and sensible heat of the heat storage material. The heat storage method using latent heat has a very complex phenomenon for heat transfer and thermal behavior because it is accompanied by a phase change in the course of heating/cooling of the heat storage material. Therefore, many studies have been conducted to produce an experimentally accessible as well as numerical approach to confirm the heat transfer and thermal behavior of phase change materials. The purpose of this study was to investigate the problems encountered during the actual heat transfer from an internal storage tank through simulation of the process of storing and utilizing thermal energy from the thermal storage tank containing charged PCM. This study used analysis methods to investigate the heat transfer characteristics of the PCM with simultaneous heating/cooling conditions in the rectangular space simulating the thermal storage tank. A numerical analysis was carried out in a state considering natural convection using the ANSYS FLUENT(R) program. The result indicates that the slope of the liquid-solid interface in the analysis field changed according to the temperature difference between the heating surface and cooling surface.

• Wind and Structures
• /
• 제7권4호
• /
• pp.265-280
• /
• 2004

This paper presents some fundamental results on the dynamics of the periodic Karman wake behind a circular cylinder. The wake is treated like a dynamical system. External forcing is then introduced and its effect investigated. The main result obtained is the following. Perturbation of the wake, by controlled cylinder oscillations in the flow direction at a frequency equal to the Karman vortex shedding frequency, leads to instability of the Karman vortex structure. The resulting wake structure oscillates at half the original Karman vortex shedding frequency. For higher frequency excitation the primary pattern involves symmetry breaking of the initially shed symmetric vortex pairs. The Karman shedding phenomenon can be modeled by a nonlinear oscillator. The symmetrical flow perturbations resulting from the periodic cylinder excitation can also be similarly represented by a nonlinear oscillator. The oscillators represent two flow modes. By considering these two nonlinear oscillators, one having inline shedding symmetry and the other having the Karman wake spatio-temporal symmetry, the possible symmetries of subsequent flow perturbations resulting from the modal interaction are determined. A theoretical analysis based on symmetry (group) theory is presented. The analysis confirms the occurrence of a period-doubling instability, which is responsible for the frequency halving phenomenon observed in the experiments. Finally it is remarked that the present findings have important implications for vortex shedding control. Perturbations in the inflow direction introduce 'control' of the Karman wake by inducing a bifurcation which forces the transfer of energy to a lower frequency which is far from the original Karman frequency.