비접촉 초음파 탐상기법을 이용한 스폿용접부 및 탄소복합체의 내부 결함평가

곽남수(Kwak, Nam-Su),이승철(Lee, Seung-Chul) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.11

NAUT(Non contact Air coupled Ultrasonic Testing)기법은 초음파 탐상법 중의 하나로서 공기중 음향 임피던스의 차이로 생기는 에너지 손실을 High Power 초음파 Pulser Receiver, PRE-AMP, 고감도의 탐촉자로 보완하여 비접촉식으로 초음파 탐상을 가능하게 하는 탐상 방법이다. NAUT는 초음파의 송신 및 수신이 안정된 상태에서 이루어지므로 기존의 접촉식 탐상으로는 불가능하였던 고온, 저온의 물질이나 시험편의 표면이 거친 부분, 좁은 지점 등에서도 탐상이 가능하다. 본 연구에서는 NAUT기법의 산업체 실용여부를 알아보기 위해 자동차생산 공정에서 많이 사용하는 스폿용접부 및 CFRP 제품에 있어 상용화 연구를 통해 다음과 같은 결과를 얻었다. 본 연구에서는 NAUT기법의 사용 여부를 알아보기 위해 자동 차 부품에서 많이 사용하는 스폿용접부 및 CFRP 부품의 내부결함 검출을 검출하였다. 스폿용접부에서는 초음파의 투과율이 높아 적색으로 나타났으며, 복층으로 된 부분은 투과율이 낮아 청색 화상이 나타났다. 또한 측정 속도를 결정하는 중요요소인 PRF(Pulse Repetition Frequency;송신펄스주기)에 따라 색상 선명도의 차이를 보였다. CFRP 시험편 또한 화상장치를 통해 취득된 각 화상 결과를 보고 내부 결함의 모양, 크기, 위치 등의 파악이 단시간에 가능하였다. 실험을 통해 NAUT기법과 화상화가 동시에 이루어짐을 확인하였고, 스폿 용접부와 CFRP 탐상에 NAUT의 적용이 가능한지 그 실현여부를 확인하였다. The NAUT (Non-contact Air coupled Ultrasonic Testing) technique is one of the ultrasonic testing methods that enables non-contact ultrasonic testing by compensating for the energy loss caused by the difference in acoustic impedance of air with an ultrasonic pulser receiver, PRE-AMP and high-sensitivity transducer. As the NAUT is performed in a state of steady ultrasonic transmission and reception, testing can be performed on materials of high or low temperatures or specimens with a rough surface or narrow part, which could not have been tested using the conventional contact-type testing technique. For this study, the internal defects of spot weld, which are often applied to auto parts, and CFRP parts, were tested to determine if it is practical to make the NAUT technique commercial. As the spot welded part had a high ultrasonic transmissivity, the result was shown as red. On the other hand, the part with an internal defect had a layer of air and low transmissivity, which was shown as blue. In addition, depending on the PRF (Pulse Repetition Frequency), an important factor that determines the measurement speed, the color sharpness showed differences. With the images obtained from CFRP specimens or an imaging device, it was possible to identify the shape, size and position of the internal defect within a short period of time. In this paper, it was confirmed in the above-described experiment that both internal defect detection and image processing of the defect could be possible using the NAUT technique. Moreover, it was possible to apply NAUT to the detection of internal defects in the spot welded parts or in CFRP parts, and commercialize its practical application to various fields.

에어와이핑 시스템 고속유동장 연구

곽남수(Nam-Su Kwak),김재열(Jae-Yeol Kim),최승현(Seung-Hyun Choi),한재호(Jae-Ho Han) 한국생산제조학회 2010 한국공작기계학회 추계학술대회논문집 Vol.2010 No.-

The air wipping system that is erupted the compressibility of a fluid through microscopic nozzle, it removes the surface of dust and heteromorphy material contact to the surface of manufacture material the spreaded air with high speed and in case of the necessity for surface coating, according to manufacture material that it can plate melted coating material to the surface, constantly. This system was applicating the dry, cooling, clean, platting plant etc. of product, usefully in the whole instruction line. The most useful application of filed is using for product an auto a galvanized steel sheet in continuous fusion zinc galvanizing. For this paper, we performed base research about that the analyzation of flowing characteristics of compressibility fluid in air wipping system for flowing fluid and the flowing visualization of air wipping flowing characteristics for using the method of ultrahigh speed image processing.

비접촉 초음파 탐상 기법을 이용한 항공기 브레이크 디스크의 신뢰성 평가

곽남수(Nam-Su Kwak),김재열(Jae-Yeol Kim),고가진(Jia-Chen Gao),박대광(Dae-Kwang Park) 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.3

Carbon fiber-reinforced silicon carbide (Cf-SiC) and SiC / SiC composites have high thermal conductivity, and excellent corrosion and wear resistance, a low coefficient for thermal expansion and are lightweight. This is why they are commonly used in parts of the aerospace industry to develop an aircraft thrust deflector, jet vane, combustion chamber, elevens, body flap, and a shingle. So, understanding how this state-of-the-art Cf-SiC affects both internal and external crack detection and determining issues during the manufacturing process of composite materials, should be evaluated according to valuation techniques in the external environment. In this paper, we apply a non-contact air ultrasonic technique of non-destructive testing techniques to perform a study on internal defect detection identification and assessment of carbon-fiber reinforced silicon carbide composites to perform basic research and applied research.

초정밀 선삭가공을 위한 글로벌스테이지의 재현성 실험

박대광(Dae-kwang Park),곽남수(Nam-su Kwak),권대주(Dae-ju Kwon),김재열(Jae-yeol Kim) 한국생산제조학회 2013 한국생산제조학회지 Vol.22 No.6

광섬유 레이저 엔코더의 실시간 피드백 및 환경보상

김재열(Jae-Yeol Kim),곽남수(Nam-Su Kwak),윤성운(Seong-Un Yun),유신(Sin You),곽이구(Lee-Gu Kwac) 한국생산제조학회 2006 한국공작기계학회 춘계학술대회논문집 Vol.2006 No.-

Recently, according to the development of mechatronics industry that was composed of NT, ST, IT, RT and the necessity of nano-parts was increased. And It was require motion accuracy of high resolution of ㎚ order in stroke of 100㎜ according as diameter of processing object. However, most machine tool has processing accuracy that do not reach in design targets by several variables. Therefore, in this research, mastered correct position information using environment compensation unit that optical fiber laser encoder and pneumatic refractive index and temperature, vibration compensation is available to solve these problem. Also, composed so that optical fiber laser encoder system using optical interference and displacement measurement and position control are available.

유한요소법을 이용한 탄성힌지 구조체의 응력 및 변형량 분석

김재열(Jae-Yeol Kim),곽남수(Nam-Su Kwak),이건(Geon Lee),한정철(Jung-Chul Han),박인우 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.4

Recently, the world is preparing for new revolution, called, ‘IT(Information Technology), NT(Nano-Technology), and BT(Bio-Technology).’ NT can be applied to various fields such as semiconductor-micro technology. Ultra precision processing is required for NT in the field of mechanical engineering. Because of radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts. In this paper, stability of ultra precision cutting unit is investigated and this unit is the kernel unit in ultra precision processing machine. According to alteration of shape and material of hinge, stability investigation is performed. Hinge shapes of micro stage in Flexure Hinge are designed in two types, where, hinge shapes are composed of round and rectangularity. Elasticity and strength are analyzed on micro stage with respect to hinge shapes by FEM analysis.

전산유체해석을 이용한 에어와이핑 노즐의 거동분석

이건(Geon Lee),김재열(Jae-Yeol Kim),곽남수(Nam-Su Kwak),나선영(Sun-Young Na) 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.4

The air wipping system that is erupted the compressibility of a fluid through microscopic nozzle, it removes the surface of dust and heteromorphy material contact to the surface of manufacture material the spreaded air with high speed and in case of the necessity for surface coating, according to manufacture material that it can plate melted coating material to the surface, constantly. This system was applicating the dry, cooling, clean, platting plant etc. of product, usefully in the whole instruction line. The most useful application of filed is using for product an auto a galvanized steel sheet in continuous fusion zinc galvanizing. For this paper, we performed base research about that the analyzation of flowing characteristics of compressibility fluid in air wipping system for flowing fluid.

7FA 가스 터빈 코팅층 건전성 평가를 위한 적외선 열화상카메라 기법 활용에 관한 연구

김재열(Jea-Yeol Kim),최철준(Choul-Jun Choi),곽남수(Nam-Su Kwak),안역식(Yeon Sik Ahn),박상기(Sang-ki Park) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.3

Key part of main equipment in a gas turbine may be likely to be damaged due to operation under high temperature, high pressure, high-speed rotation, etc. Accordingly, the cost for maintenance increases and the damaged parts may cause generation to stop. Blades are made of precipitation hardening Ni superalloy IN738 and the like for keeping hot strength. The surface of a blade is thermal-sprayed, using powder with main compositions such as Ni, Cr, Al, etc. in order to inhibit hot oxidation. Conventional regular maintenance of the coating layer of a blade is made by FPI (Fluorescent Penetrant Inspection) and MTP (Magnetic Particle Testing). Such methods, however, are complicated and take long time and also require much cost. In this study, defect diagnostics were tested for the coating layer of an industrial gas turbine blade, using an infrared thermography camera. It can advantageously save expenses and time as compared to conventional test methods. For the infrared thermography method, however, thermo-load must be applied onto a tested specimen and it is difficult to quantify the measured data. To solve the problems, this essay includes description about producing a specimen of a gas turbine blade (bucket), applying thermo-load onto the produced specimen, photographing thermography images by an infrared thermography camera, analyzing the thermography images, and pre-testing for analyzing defects on the coating layer of the gas turbine blade.

고로의 연소효율을 높이기 위한 화염영상 정밀 검출 및 화염제어

김재열(Jae-Yeol Kim),이승철(Seung-Chul Lee),곽남수(Nam-Su Kwak),한재호(Jae-Ho Han) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.6

Pulverized coal (PC) has become an important auxiliary fuel in the iron and steel industry since the technique of pulverized coal injection (PCI) was developed for iron making. The combustion efficiencies of pulverized coal in blowpipes and tuyeres under various operational conditions are numerically predicted to determine the performance levels with regard to different locations of the nozzles in a blast furnace. A variety of parameters, including the pulverized coal quantities, oxygen amounts, inlet temperatures of the tuyeres, and the mass flow rate of coal carrier gas are taken into consideration. Also, in order to develop greater efficiency than those of existing coal injection systems, this study applies a flame measurement system using a charge-coupled device (CCD) camera and a frame grabber. It uses auto sampling algorithms from the flame shape information to determine the device for the optimal location control for PCI. This study finds further improvements of the blast furnace performance via the control of the PCI locations.

폴리우레탄 성형머신 설계 및 제작

김재열(Jae-Yeol Kim),고명석(Myung-Seok Ko),곽남수(Nam-Su Kwak),최철준(Chol-Jun Choi),한재호(Jae-Ho Han) 한국기계가공학회 2006 한국기계가공학회 춘추계학술대회 논문집 Vol.2006 No.-

Present filter manufacture is circumstance that is producing all in medium and small enterprises. Department filter makes through various complicated process. Specially, Urethan Forming process among manufacturing process requires worker's high work strength. Constituent that is uneasy from explosion and fire risk exists, and job evasion phenomenon is seen. Difficulty of manpower supply and demand who is specialized deviation lowering a ways exists. Badness increases high in real form phenomenon of standardization, process of manufacturing precess. Wish to minimize badness of product and improve productivity, authoritativeness developing Urethan Forming machine to improve working environment of correction of deformities and core net.