• 지구물리와물리탐사
• /
• 제22권2호
• /
• pp.49-55
• /
• 2019

본 연구에서는 주기적 송신원 추출 기법을 사용한 완전 파형 역산 시 목적함수의 안정적인 수렴을 위해 참조 송신원 부분집합을 사용하는 방법을 제안하였다. 완전 파형 역산은 반복적인 파동 전파 모델링을 통해 수행되며, 송신원 개수가 증가할수록 계산 시간이 증가하게 된다. 완전 파형 역산의 계산량을 줄이기 위한 기법들 중 하나로, 주기적 송신원 추출 기법을 사용할 수 있지만 이 경우 역산 초기부터 목적함수가 진동하며 수렴하기 때문에 수렴 판별에 문제가 생기게 된다. 이러한 문제를 해결하고자 본 연구에서는 주기적 송신원 추출 기법을 이용해 모델을 갱신하되, 고정된 참조 송신원 부분집합을 이용해 목적함수를 계산하는 방법을 제안하였다. Marmousi 속도 모델을 이용한 완전 파형 역산 예제를 통해 참조 송신원 부분집합을 이용하면 주기적 송신원 추출 기법을 사용하더라도 목적함수가 안정적으로 수렴할 수 있음을 확인하였다.

• Wind and Structures
• /
• 제36권6호
• /
• pp.367-377
• /
• 2023

This study proposes a few-shot learning model for extrapolating the wind pressure of scaled experiments to full-scale measurements. The proposed ML model can use scaled experimental data and a few full-scale tests to accurately predict the remaining full-scale data points (for new specimens). This model focuses on extrapolating the prediction to different scales while existing approaches are not capable of accurately extrapolating from scaled data to full-scale data in the wind engineering domain. Also, the scaling issue observed in wind tunnel tests can be partially resolved via the proposed approach. The proposed model obtained a low mean-squared error and a high coefficient of determination for the mean and standard deviation wind pressure coefficients of the full-scale dataset. A parametric study is carried out to investigate the influence of the number of selected shots. This technique is the first of its kind as it is the first time an ML model has been used in the wind engineering field to deal with extrapolation in wind performance prediction. With the advantages of the few-shot learning model, physical wind tunnel experiments can be reduced to a great extent. The few-shot learning model yields a robust, efficient, and accurate alternative to extrapolating the prediction performance of structures from various model scales to full-scale.

• Tribology and Lubricants
• /
• 제13권2호
• /
• pp.39-45
• /
• 1997

The shot peening treatment were conducted for improving the strength of rolling contact fatigue of machine element like a gear. This paper was undertaken to analyze the influence of shot peening treatment for inner race of ball bearing on the rolling contact fatigue. Shot peening treatment were applied to the full hardened and the carbonitrided bearing. And the rolling contact fatigue life test and X-ray diffraction test were carried out. The results of this study showed that the fatigue life of ball bearing in the clean and the contaminated oil could be improved by shot peening treatment. This effect was found to be more pronounced to the full hardened bearing. These facts might be due to the generation of compressive residual stress and the strain hardening of surface layer by shot peening treatment. The failure of the shot peened bearing were presumed to initiate at surface.

• 한국정보과학회 언어공학연구회:학술대회논문집(한글 및 한국어 정보처리)
• /
• 한국정보과학회언어공학연구회 2022년도 제34회 한글 및 한국어 정보처리 학술대회
• /
• pp.47-52
• /
• 2022

환자와 주변인들에게 다양한 문제를 야기하는 치매와 조현병 진단을 위한 모델을 제안한다. 치매와 조현병 진단을 위해 프로토콜에 따라 녹음한 의사와 내담자 음성 시료를 전사 작업하여 분류 태스크를 수행하였다. 사전 학습한 언어 모델의 MLM Head를 이용해 분류 태스크를 수행하는 Prompt 기반의 분류 모델을 제안하였다. 또한 많은 수의 데이터 수를 확보하기 어려운 의료 분야에 효율적인 Few-Shot 학습 방식을 이용하였다. CLS 토큰을 미세조정하는 일반적 학습 방식의 Baseline과 비교해 Full-Shot 실험에서 7개 태스크 중 1개 태스크에서 macro, micro-F1 점수 모두 향상되었고, 3개 태스크에서 하나의 F1 점수만 향샹된 것을 확인 하였다. 반면, Few-Shot 실험에서는 7개 태스크 중 2개 태스크에서 macro, micro-F1 점수가 모두 향상되었고, 2개 태스크에서 하나의 F1 점수만 향상되었다.

• 한국기계연구소 소보
• /
• 통권15호
• /
• pp.75-87
• /
• 1985

A review was performed on fatigue life prediction and strength evaluation of shot peened parts. Fatigue strength of machine parts can be improved by shot peening due to compressive residual stresses on such parts. Compressive residual stress cannot be uniquely define by peening intensity. Several measuring methods of residual stress and the principle of hole drilling method are presented. Exploratory measurement of residual stress was performed on the shot peened SM35C plate with the hole drilling method. Fatigue life and failure location of shot peened parts under bending load can be predicted by a damage parameter which is incorporated with material properties, residual stress, and applied stress conditions. Some method are presented to predict the fatigue strength of shot peened parts at any given life. Shot peening gives its full benefit to the notched machine parts of high strength steels.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 추계학술대회 논문요약집
• /
• pp.193-193
• /
• 2003

• 한국운동역학회지
• /
• 제17권2호
• /
• pp.177-185
• /
• 2007

Even though there were no clear definitions of the short game and short game distance, short game capability is crucial for a good golf score. Generally, chip shot and pitch shot are regarded as two principal components of the short game. Chip shot is a short, low trajectory shot played to the green or from trouble back into play. Pitch shot is a high trajectory shot of short length. Biomechanical studies were conducted usually to analyze full swing and putting motions. The purpose of the study was to reveal the kinematical differences between professional golfers' 30 yard $53^{\circ}wedge$ chip shot and $56^{\circ}wedge$ pitch shot motions. Fifteen male professional golfers were recruited for the study. Kinematical data were collected by the 60 Hz three-dimensional motion analysis system. Statistical comparisons were made by paired t-test, ANOVA, and Duncan of the SPSS 12.0K with the $\alpha$ value of .05. Results show that both the left hand and the ball were placed left of the center of the left and right foot at address. The left hand position of the chip shot was significantly left side of that of the pitch shot. But the ball position of the pitch shot was significantly right side of that of the chip shot. All body segments aligned to the left of the target line, open, at address. Except shoulder, there were no significant pelvis, knee, and feet alignment differences between chip shot and pitch shot. These differences at address seem for the ball height control. Pitch shot swing motions(the shoulder and pelvis rotation and the club head travel distance) were significantly bigger than those of the chip shot. Club head velocity of the pitch shot was significantly faster than that of the chip shot at the moment of impact. This was for the same shot length control with different lofted clubs. Swing motion differences seem mainly caused by the same shot length control with different ball height control.

• 한국정보과학회논문지:소프트웨어및응용
• /
• 제27권3호
• /
• pp.201-209
• /
• 2000

샷 경계 검출 알고리즘은 영상 제작시 사용된 컷, 와이프, 디졸브 등의 편집 효과로 인해 완벽한 결과를 기대하기 어렵다. 따라서 정확한 샷 경계를 얻기 위해서는 수작업에 의한 검증이 필요하다. 본고에서는 시각 율동을 이용한 샷 경계 검증 방법을 제시한다. 시각 율동은 영상의 내용 변화를 요약한 한 장의 이미지이다. 편집 효과는 수직선, 사선, 곡선, 점진적 색상의 변화 등 시각적으로 인지 가능한 형태로 시각 율동에 표현된다. 따라서 영상을 재생시키지 않고도 시각 율동의 변화만을 파악하여 샷 경계로 의심되는 부분들을 쉽고 빠르게 찾아낼 수 있다. 또한 이 특성을 이용한 샷 검증기를 구현하여 시각 율동의 유용성을 보인다.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2002년도 춘계학술대회 논문집
• /
• pp.112-118
• /
• 2002

Injection molding process factors such as molding temperature, injection pressure, flow rate and flow velocity, must be controlled properly in filling and packing phases in the injection molding process. In this study, effects of these factors on the injection molding were investigated through the flow analysis fur the filling and packing phases. Molding troubles like flow mark, weld line, sink mark, short shot and warpage can be caused by these injection molding process factors. Among them, the short shot was caused by that the packing pressure could not reach properly to the filling end part in the packing phase and hence the flow rate could not be supplied to the full. In addition, as the flow rate for the volumetric shrinkage during the frozen phase could not be supplied properly by the packing pressure, the short shot appeared. Here, the volumetric shrinkage reduced with increasing the packing pressure and also the warpage of molded part increased with increasing the packing pressure.

• 한국공작기계학회논문집
• /
• 제11권4호
• /
• pp.44-53
• /
• 2002

Injection molding process factors such as molding temperature, injection pressure, flow rate and flow velocity, must be controlled properly in filling and packing phases in the injection molding process. In this study, effects of these factors on the injection molding were investigated through the flow analysis for the filling and packing phases. Molding troubles like flow mark weld line, sink ma가 short shot and warpage car be caused by these injection molding process factors. Among them the short shot was caused by the fact that the packing pressure could not reach properly to the filling end part in the packing phase and hence the flow rate could not be supplied to the full. In addition as the flow rate for the volumetric shrinkage during the f개zen phase could not be supplied Properly by the packing pressure, the short shot appeared. Here, the volumetric shrinkage reduced with increasing the packing pressure and also the warpage of molded part increased with increasing the packing Pressure.