• 한국생산제조학회지
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• 제22권4호
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• pp.723-729
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• 2013

The contraction and expansion noise of a refrigerator are investigated, and some effective methods are proposed to reduce the level and occurrence frequency of noise. First, the noise of a refrigerator is measured to estimate the frequency spectrum and occurrence frequency of noise. Second, a sound visualization was conducted using an acoustic camera to determine the location of the noise source. From the results, it was observed that the internal part mainly producing noise was the third shelf in the freezer room. A method to estimate the acceleration on the location of the noise source is introduced to analyze the contraction and expansion noise precisely and accommodate experimental convenience. Noise reduction methods such as the replacement of the existing shelf with glass shelves, adoption of rail slides, and increase of roughness on the contact surface of the shelf are proposed and tested.

• International Journal of Control, Automation, and Systems
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• 제5권1호
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• pp.61-69
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• 2007

In this paper, we developed not only a reliable sound localization system including a VAD(Voice Activity Detection) component using three microphones but also a face tracking system using a vision camera. Moreover, we proposed a way to integrate three systems in the human-robot interaction to compensate errors in the localization of a speaker and to reject unnecessary speech or noise signals entering from undesired directions effectively. For the purpose of verifying our system's performances, we installed the proposed audio-visual system in a prototype robot, called IROBAA(Intelligent ROBot for Active Audition), and demonstrated how to integrate the audio-visual system.

• 한국주조공학회지
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• 제18권3호
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• pp.262-270
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• 1998

Gravity tilt pour casting can effectively guarantee the reduction of various casting defects by controlling the rotation speed and the tilting angle of the mold during tilt pouring. The relationship between casting process parameters and the soundness of castings has been investigated in order to determine the optimum process variables in the gravity tilt pour casting process. In order to evaluate the effect of rotation speed on mold filling patterns, a video camera was employed to visualize the in-situ fluid flow behavior of the molten metal, and the relevant fluid velocity was also estimated. X-ray and mechanical tests were also performed to evaluate the effect of fluid velocity on casting quality. With the rotation speed lower than 0.5 r.p.m., which is nearly corresponding to the critical velocity of stability in the fluid flow, sound castings were obtained without having any casting defects. It can be concluded that the gravity tilt pour casting process is an effective process for manufacturing sound casting products with enhanced physical and mechanical properties.

• 한국콘텐츠학회논문지
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• 제12권5호
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• pp.81-90
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• 2012

2008년 Full HD 동영상 촬영이 가능한 Canon EOS 5D Mark II가 출시된 이래, 영상 제작 현장에서 DSLR 카메라의 활용이 매우 증가하고 있다. 본 논문에서는 5D Mark II 카메라가 지니고 있는 동영상 기능의 장단점을 분석하고, 오늘날 영화 제작 현장에서 가장 널리 사용되고 있는 RED 카메라와 비교해 볼 것이다. 이를 통하여 영화 제작 현장에서의 DSLR 카메라의 활용성에 대해서 살펴보도록 하겠다. DSLR 카메라는 면적이 큰 이미지 센서를 사용하여 화질이 뛰어나고, 좋은 품질의 다양한 렌즈를 활용할 수 있다는 장점을 지니고 있으며, 기존의 HD 카메라들과 비교하면 아주 작아진 크기와 가벼운 무게를 지니고 있다. 물론 동영상 촬영 시의 음향 녹음 문제나 다양한 부가 장비의 개발과 같은 더욱 개선되어야 할 부분이 남아있기는 하지만 DLSR 카메라가 지닌 뛰어난 활용성은 영화 제작의 새로운 가능성을 제시하고 있다.

• 대한기계학회논문집A
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• 제35권7호
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• pp.737-743
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• 2011

서비스 로봇은 비전 카메라, 초음파 센서, 레이저 스캐너, 마이크로폰 등과 같은 다양한 센서를 장착하고 있다. 이들 센서들은 이들 각각의 고유한 기능을 가지고 있기도 하지만, 몇몇을 조합하여 사용함으로써 더욱 복잡한 기능을 수행할 수 있다. 음성영상 융합은 서로가 서로를 상호보완 해주는 대표적이면서도 강력한 조합이다. 사람의 경우에 있어서도, 일상생활에 있어 주로 시각과 청각 정보에 의존한다. 본 발표에서는, 음성영상 융합에 관한 두 가지 연구를 소개한다. 하나는 음원 방향 검지 성능의 향상에 관한 것이고, 나머지 하나는 음원 방향 검지와 얼굴 검출을 이용한 로봇 어텐션에 관한 것이다.

• 한국컴퓨터정보학회논문지
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• 제15권2호
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• pp.75-81
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• 2010

타격감은 슈팅 게임이 가져야할 중요한 요소 중의 하나이다. 게임 개발자들은 시각(특수) 효과, 음향 효과, 진동효과, 애니메이션, 카메라 테크닉 등 다양한 기법을 사용하여 타격감을 높이려 노력해왔다. 이 논문은 이러한 다양한 기법들이 2D 슈팅게임에서 타격감에 어떠한 영향을 미치는지에 대한 실험 결과를 소개하고자 한다. 우리는 사용자를 대상으로 2 가지 실험을 수행하였는데, 첫 번째 실험은 발사체에 적용된 4 가지 효과(시각, 애니메이션(반동), 음향, 진동)에 대한 16 가지 실험 세트로 구성하였고 두 번째 실험은 발사체와 피사체 각각에 시각 효과와 음향 효과만 적용하여 마찬가지로 16 가지 실험 세트로 구성하였다. 실험 결과 모든 개별적인 기법은 모두 유의한 분석 결과를 나타내었으며, 시각 효과와 애니메이션보다는 음향 효과와 진동 효과가 더욱 효과적인 기법이고 발사체 보다는 피사체가 더 중요하다는 것을 알 수 있었다.

• 한국수소및신에너지학회논문집
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• 제28권1호
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• pp.106-112
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• 2017

The present study describes flow induced noise generated from a ball valve used for a gas pipeline. Noise generation from a ball valve mainly induces by interference between unstable(or fluctuating) leakage flow and pipe wall when the ball valve is working closed or opened. To measure the positions of the noise source and the amplitude of noise with respect to measuring frequencies, a commercial acoustic camera is introduced. Noise characteristics generated by the ball valve have been performed by four valve opening rates: 30, 50, 70 and 100 percents. It is noted that 100 percent opening rate means that the valve is fully opened. Throughout the experimental measurements using the acoustic camera, the location of the noise source and the noise amplitude with respect to the frequencies for the test ball valve are clearly evaluated. It is found that the dominant frequencies come from the fluctuating flow at the downstream of the ball valve for four opening rates are observed between 3,000Hz and 3,200Hz. Maximum noise amplitude comes from the ball valve reaches 75dB at the valve opening rate of 50 percent.

• 한국분무공학회지
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• 제18권3호
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• pp.126-131
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• 2013

This paper describes the effect of ultrasonic frequency(f) on the atomization and deformation characteristics of single water droplet in an acoustic levitation field. To achieve this, the ultrasonic levitator that can control sound pressure and velocity amplitude by changing frequency was installed, and visualization of single water droplet was conducted with high resolution ICCD and CCD camera. At the same time, atomization and deformation characteristics of single water droplet was studied in terms of normalized droplet diameter($d/d_0$), droplet diameter(d) variation and droplet volume(V) variation under different ultrasonic frequency(f) conditions. It was revealed that increase of ultrasonic frequency reduces the droplet diameter. Therefore, it is able to levitate with low sound pressure level. It also induces the wide oscillation range, large diameter and volume variation of water droplet. In conclusion, the increase of ultrasonic frequency(f) can enhance the atomization performance of single water droplet.

• Journal of Welding and Joining
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• 제23권5호
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• pp.14-19
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• 2005

In high speed $CO_2$ welding, it has been blown to produce no sound bead with undercut or humping bead. In this study welding phenomena through synchronized high speed camera and output welding voltage and current waveform has been analyzed. For the purpose to improve a welding bead, effect of short circuit current rise slope has been examined. With commercial power source it was produced no sound bead by instantaneous short circuit, long arc period and stubbing at welding speed 2.5mm/min Humping bead or undercut were showed by instantaneous short circuit and long arc period. Also, the weld bead was not formed during the long short circuit period after stubbing start and long arc extinguishment period after wire sticking by failure of arc regeneration, because the droplet was not transferred to weld pool. With increasing short circuit current rise slope the frequency of stubbing was decreased and the normal short circuit rate was increased. A control of short circuit current rise slope was effective factor in high speed welding.

• 디지털산업정보학회논문지
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• 제19권1호
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• pp.119-127
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• 2023

Recently, deep learning has been used in the development of various institutional devices and services to help the visually impaired people in their daily lives. This is because not only are there few products and facility guides written in braille, but less than 10% of the visually impaired can use braille. In this paper, we propose a system that recognizes beverage cans in real time and outputs the beverage can name with sound for the convenience of the visually impaired. Five commercially available beverage cans were selected, and a CNN model and a YOLO model were designed to recognize the beverage cans. After augmenting the image data, model training was performed. The accuracy of the proposed CNN model and YOLO model is 91.2% and 90.8%, respectively. For practical verification, a system was built by attaching a camera and speaker to a Raspberry Pi. In the system, the YOLO model was applied. It was confirmed that beverage cans were recognized and output as sound in real time in various environments.