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양정직(Yang, Jeong-Jik),이동주(Lee, Dong-Ju) 한국소음진동공학회 2010 한국소음진동공학회 논문집 Vol.20 No.11
The relation between the vibration induced from machinery and the radiated sound is complicated. Acoustic intensity method is widely used to obtain the accuracy of noise measurement and noise identification. In this study, as groundwork, the complex acoustic intensity method is performed to identify noise source and transmission path on different free space point source fields. As an industrial application, the complex acoustic intensity method is applied to HVAC to identify sound radiation characteristics in the near field. Experimental complex acoustic intensity method was applied to HVAC, it is possible to identify noise sources in complicated sound field characteristics which noise sources are related with each other, and certificate the validity of complex acoustic intensity. Especially, it can be seen that complex acoustic intensity method using both of active and reactive intensity is vital in devising a strategy for identification of noise. Also, the vector flow of acoustic intensity was investigated to identify sound intensity distributions and energy flow in the near field of HVAC.
3D프린팅 주형의 표면품질 향상을 위한 도형제 적용기술 연구
이환종,양정직,현효진 한국생산제조학회 2018 한국생산제조학회지 Vol.27 No.6
Three-dimensional (3D) printing technology is a new and widely use technology in the manufacturing industry. However, the domestic manufacturing industry is underutilized due to various manufacturing flaws and surface quality problems. This study intended to derive ways to improve the surface quality of products by improving the surface roughness of the sand mold manufactured by 3D printing. The test results confirmed improved viscosity control of the mold wash coated on the surface of the sand mold. In conclusion, it was possible to derive that the mold wash had a direct effect on the sand mold surface and to improve surface quality through coating methods on the mold and core.
Mask R-CNN과 겹침 처리 알고리즘을 활용한 상단의 원형 객체 검출 및 자세 추정
윤석현,양정직,김청준,황면중 제어·로봇·시스템학회 2023 제어·로봇·시스템학회 논문지 Vol.29 No.12
. This paper proposes an algorithm for detecting and estimating the pose of top objects in a complex environment where thin metal circular plates are randomly stacked. In complex environments where multiple instances of the same object are randomly stacked, the robot needs to detect and compare objects to identify the top ones for grasping. Our approach involves a combination of deep learning-based instance segmentation and an overlap handling algorithm for precise top object detection. Subsequently, leveraging three-dimensional geometric data, we estimate the object's pose by determining its plane. To validate the proposed algorithm, we constructed two environments consisting of objects with different sizes and thicknesses. The first experiment quantitatively validated the object detection and overlap handling algorithm. The second experiment quantitatively compared different plane estimation algorithms. The third experiment quantitatively compared the pose of objects using the G-ICP (Generalized Iterative Closest Point) algorithm and the proposed algorithm against the ground truth pose. Additionally, we performed a qualitative comparison by visualizing the poses estimated by each algorithm in the images. In the experimental results, the overlap handling algorithm had an average success rate of 84.21%. Additionally, pose estimation using G-ICP before plane estimation frequently resulted in issues like drift in the center point and frequent misalignment with areas other than the object. On the other hand, pose estimation using G-ICP after plane estimation and the proposed algorithm yielded similar performance with average ADD-S values of 6mm or less. However, the pose estimated using the proposed algorithm resulted in a minimum 0.25x reduction in execution time compared to the G-ICP algorithm.
사형 주조 3D 프린팅용 소재의 기계적 특성 및 신뢰성
손현진,장성완,이환종,양정직,정영근,배창준,Son, Hyeon Jin,Jang, Seongwan,Lee, Hwan Jong,Yang, Jeong Jik,Jeong, Yeong Geun,Bae, Chang-Jun 한국재료학회 2020 한국재료학회지 Vol.30 No.1
Sand casting 3D printing uses a binder jetting method to produce a mold having complicated shape by spraying a binder on sand coated with activator. Appropriate heat treatment process in sand mold fabrication can increase the degree of polymerization to improve flexural strength. However, long heat treatment of over 24 hours decreases flexural strength and reliability due to chemical bond decomposition through thermal degradation. The main role of the activator is to control the reaction rate between the polymer chains. As a result, when the activator composition is increased from 0.15 wt% to 0.25 wt%, the flexural strength is increased by 218 N/㎠. However, excess activator (0.40 wt%) has been shown to decrease reliability without increasing flexural strength. The main role of the binder is to control the flexural strength of the specimen. As the binder composition is increased from 2.00 wt% to 4.00 wt%, the flexural strength increases to about 255 N/㎠, indicating the maximum flexural strength increase. Finally, the reliability of the flexural strength of the fabricated specimens is evaluated by a Weibull plot. Weibull modulus calculations are used to evaluate the flexural strength reliability of the specimens, and maximum reliability value of 11.7 is obtained at 0.20 wt% activator composition. Therefore, it is confirmed that this composition has maximum flexural strength reliability.
서지원(Ji-Won Seo),양정직(Jeong-Jik Yang),김진호(Jin-Ho Kim),임종완(Jong-Wan Lim) 한국가스학회 2017 한국가스학회지 Vol.21 No.3
국내 CNG Bi-fuel Kit를 개조한 차량들은 대부분 Diaphragm 감압방식을 적용한 기계식 레귤레이터를 장착하여 운행 중에 있다. 하지만 Diaphragm의 재질 특성 및 기계식 압력제어 방식의 특성 상 다양한 문제점들이 발생되고 있으며, 이를 개선하기 위한 연구들이 진행되고 있다. 본 연구에서는 CNG 차량용 레귤레이터의 압력제어방식에 따른 성능특성 확인 및 비교 분석 진행을 통해 개선방안을 도출하고자 하였다. 실험 결과에 따르면 Diaphragm을 적용한 감압방식이 Piston을 적용한 방식보다 일반적인 성능에서 유리하였으나 주변 온도환경 변화에 따른 변동 폭이 큰 것을 확인하였다. 또한 전자식 압력제어를 통해 레귤레이터의 일반적인 성능을 향상시킬 수 있음을 확인하였다. The domestic vehicles remodeling the “CNG Bi-fuel Kit” are mostly in operation with installing the mechanical regulator applying the Diaphragm. However, due to the material characteristics of Diaphragm and characteristics of mechanical pressure control method, various problems are happening. This study tries to deduce the improvement plan through the checking of performance characteristics according to the pressure control method of CNG regulator and progress of comparative analysis. According to the test result, the decompression method applying the Diaphragm has advantage compared to the method applying the Piston. Furthermore, it was confirmed that through the electronic pressure control, it is possible to improve the general performance of the regulator.