• 소성∙가공
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• 제19권4호
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• pp.224-229
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• 2010

During the multi-pass wire drawing process, wires suffer a great amount of plastic deformation that is through the cross-section. This generates tensile residual stress at surface of drawn wires. The generated residual stress on surface is one of the problems for quality of wires so that prediction and reduction of residual stresses is important to avoid unexpected fracture. Therefore, in this study, the effect of process variables such as semi-die angle, bearing length and reduction ratio on the residual stress was evaluated through Finite Element Analysis. Based on the results of the Analysis, a prediction model was established for predicting residual stress on the surface of high carbon steel(AISI1072, AISI1082). To identify the effectiveness of the proposed model, X-ray diffraction is used to measure the residual stresses on the surface. As the result of the comparison between calculated residual stresses and measured residual stresses, the model could be used to predict residual stresses in cold drawn wire.

• 설비공학논문집
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• 제13권9호
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• pp.853-859
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• 2001

A pulsed tracer gas technique is applied to measure distributions of local mean age and residual life time of air in a half-scale experimental chamber. The room airflow patterns are flow-visualized by a Helium bubble generator for three different exhaust locations. A supply slot is located at the top of a right wall, and an exhaust slot is either at bottom-left(Case 1), bottom-right(Case 2), or top-left(Case 3) location. Results show that the distribution of LMA and LMR are different from each other, but both of them are closely related to the airflow pattern in the space. Results on overall room ventilation effectiveness are provided depending upon ventilation airflow rates for three different supply-exhaust configurations.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.80-85
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• 1999

Residual stress in the forged products directly affects material stability, resistance to deformation, accuracy, and fatigue life of products. It is very important to study the residual stress distributions in forged products and to monitor operating conditions for the minimum tensile or maximum compressive residual stresses. As a way to study the residual stress formation due to radial forging, a three dimensional theoretical model was developed using ANSYS finite element program. Using the developed model, residual stress distributions in forged product were calculated and selected results were compared with the published experimental data to verify the effectiveness of the developed model.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.96.3-96
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• 2002

A scheme of clarifying fault feature in the residual is given for model-based fault detection and diagnosis of control systems. It is based on the residual generation using a robust filter and the noise suppresion in test statistics of the residual by multi-scale discrete wavelet transform. By clarifying the fault feature in the residual, the difficulties of existing model based approaches via adopting a threshold can be overcomed and it has advantage of taking the false alarm and missed detection into acount at the same time, which can make the fault detection and diagnosis easy and correct. To show the effectiveness of our approach, the simulation results are illustrated for a linear syste...

• 한국생산제조학회지
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• 제7권5호
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• pp.120-126
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• 1998

Second step shot peening was applied on both smooth specimen and U-notch specimen in order to investigate the stress distribution and the improvement in fatigue strength. Various experiments and measurements such as rotary bending fatigue test and the measurement of compressive residual stress were performed. The results showed that the fatigue strength of second step shot peened specimens increased by 34 percent compared to that of unpeened ones. Compressive residual stress also considerably increased, which resulted in the increase of fatigue strength. finite element analysis showed that shot peening is effective in decreasing the bending stress by external force. The effectiveness of shot peening in reducing the compressive residual stress was anticipated by the superposition of the concentrated stress and the compressive residual stress.

• Journal of Korean Neurosurgical Society
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• 제38권5호
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• pp.344-349
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• 2005

Objective : The Bertrand's method of selective peripheral denervation for spasmodic torticollis has already been established as being an effective and safe method. However, such effectiveness has not yet been established in Korea. The authors have performed several cases of selective denervation for the treatment of spasmodic torticollis and we hereby describe the details of the operative method to determine the effectiveness of the method. Methods : Ten patients who had the selective denervation for the spasmodic torticollis from October 1997 to December 2003, were analyzed. There were 4 rotational and 6 combined types [3 rotational plus retrocollis, 3 rotational plus laterocollis]. We performed preoperative electromyograms and neck muscle tonograms in all cases. The technique was used to involve denervation of the ipsilateral posterior paraspinal muscles. Denervation of the sternocleidomastoid muscle was performed on the contralateral side for rotational torticollis and on the ipsilateral side for laterocollis combined type. The surgery was followed by a rigorous physical therapy program. Results : The surgical results were divided into 4 groups labeled excellent, good, fair, and poor. There were 5 excellent patients who showed no detectable abnormal movements, 4 good patients who showed slight residual deviations or slight residual abnormal movements, and 1 fair patient with appreciable residual abnormal movements. Postoperative pain was well tolerated. There was no significant surgical complications. Conclusion : The study confirms that selective peripheral denervation for the treatment of spasmodic torticollis is a very useful and safe surgical technique.

• Journal of Periodontal and Implant Science
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• 제28권2호
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• pp.371-376
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• 1998

This study presents an evaluation of the effectiveness of nonsurgical subgingival scaling and root planing related to initial pocket depth, type of teeth, and individual root surfaces. A total of 110 teeth designated for periodontal surgery in 67 patients with marginal periodontitis were selected and received thorough scaling and root planing with standard rigid Gracey curettes. After a healing period of 4 to 8 weeks, residual calculus was assessed at the time of periodontal surgery following the reflection of mucoperiosteal flap. The results demonstrated a high correlation between the percentage of residual calculus and initial pocket depth. It was further noted that tooth type and involved root surface also influenced the rate of calculus remnant. The results of this study suggest that complete removal of subgingival calculus utilizing conventional instrumentation via closed approach is rare.

• 대한기계학회논문집A
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• 제22권2호
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• pp.258-267
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• 1998

This study reviews the influence function method(IFM) for calculating stress intensity factors (SIFs, K) and modifies it to apply for the estimating the residual fatigue life for the cracked components under complex stress fields. An IFM has been developed to analyze SIFs for surface cracks which are subjectedto nonuniformly distributed stresses. Through elastic superposition, the influence function method properly accounts for redistribution of stress as the crack grows through the component. This influence function is unique to the given geometry and independent of the loading. Some examples have been provided to show the effectiveness of the IFM including the distributions of K in a residual stress field. The significant effect of residual stress upon fatigue crack growth in a welded component has been demonstrated with the IFM.

• 제어로봇시스템학회논문지
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• 제18권4호
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• pp.308-313
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• 2012

Robust tuning rules of the motion profile are proposed to minimize the residual vibration. For asymmetric S-curve profile, tuning rules are analytically formulated using Laplace-domain approach. When the system modeling is known exactly, by placing a single zero of the motion profile on the pole of the system, the residual vibration can be perfectly eliminated under undamped system. However, if there are some amounts of the modeling errors, the residual vibration significantly increases. To track this issue, the robust tuning rules against modeling error are discussed. One of the proposed robust tuning rules is placing the multiple zeros of the motion profile on the pole of the system, and the other is placing the zeros of the motion profile around the pole of the system. Thanks to the proposed robust tuning rules, motion profile becomes more robust to modeling errors while minimizing the residual vibration. By simulation, the effectiveness of the proposed robust tuning rules is verified.

• 융합정보논문지
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• 제11권10호
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• pp.45-52
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• 2021

본 논문에서는 U-Net 기반의 semantic segmentation 방법에서 정확도를 개선하기 위한 Atrous Residual U-Net (AR-UNet)을 제안하였다. U-Net은 의료 영상 분석, 자율주행 자동차, 원격 감지 영상 등의 분야에서 주로 사용된다. 기존 U-Net은 인코더 부분에서 컨볼루션 계층 수가 적어 추출되는 특징이 부족하다. 추출된 특징은 객체의 범주를 분류하는 데 필수적이며, 부족할 경우 분할 정확도를 저하시키는 문제를 초래한다. 따라서 이 문제를 개선하기 위해 인코더에 residual learning과 ASPP를 활용한 AR-UNet을 제안하였다. Residual learning은 특징 추출 능력을 개선하고, 연속적인 컨볼루션으로 발생하는 특징 손실과 기울기 소실 문제 방지에 효과적이다. 또한 ASPP는 특징맵의 해상도를 줄이지 않고 추가적인 특징 추출이 가능하다. 실험은 Cityscapes 데이터셋으로 AR-UNet의 효과를 검증하였다. 실험 결과는 AR-UNet이 기존 U-Net과 비교하여 향상된 분할 결과를 보였다. 이를 통해 AR-UNet은 정확도가 중요한 여러 응용 분야의 발전에 기여할 수 있다.