C-Scan 장치를 이용한 초음파 탐상에 관한 연구 [Ⅲ]

玄淸男 弘益大學校 産業技術硏究所 2005 産業技術 Vol.15 No.-

In this study, the flaws in the several test specimens are detected by using a C-Scan system. The following results are obtained through this research; 1. How to detect the flaws in the specimens 2. How to determine the depth of the flaws in the specimens,. How to determine the size of the flaws in the specimens 3. How to determine if the specimen is in one piece or not and how to detect defects at the joining part 4. Analysis by using Linear Profile and 3D View In order to determine the depth and size of the flaws in the specimens precisely, it is very important to operate the C-Scan system properly

초음파를 이용한 형상인식에 관한 연구

玄淸男 홍익대학교 산업기술연구소 1996 産業技術 Vol.6 No.-

Recently a number of researches have been performed for the various methods of shape recognition of objects. An algorithm was developed for the recognition fo shape of arbitrary objects using ultrasonics. It was possible to measure the distance, the thickness and the real shape of the objects as well as the image of them using the experimental method developed here. Thus, the following results were obtained: (1) the basic algorithm for the recognition of shape of arbitrary objects can be applied to the real structures in the industry, (2) the error of measurement using the current method in within 1-6% compared to the real shape, and (3) in order to obtain the more accurate results, the minor errors in the algorithm and for the incident waves are being studied.

공구 윗면 경사각의 변화에 따른 6/4 Brass의 기계적 성질에 관한 연구

현청남 홍익대학교 산업기술연구소 1992 産業技術 Vol.1 No.-

In turning operation, it is the material of work piece and cutting tool, feed and cutting speed, the depth of cut and rake angle that influence upon the accuracy of demension, the manufacturing efficiency, the extension of tool life and surface roughness. Especially, the identification of cutting force due to the change of tool rake angle, which exerts a grate influence on the turning, is very important. In this study, the cutting force of test materials, surface roughness were measured by experiment. And the cutting resistance due to the change of tool rake angle was calculated by applying the three demensional cutting formula, then the conditions of optimal machinability were obtained taking into consideration of the material characteristics. From the experimental results, the conditions of optimal machinability classified by the test materials are as follows: 1) The normal force acting on the tool face has the minimum value at the true rake angle of 10˚ -15˚ in Brass. 2) The specific cutting resistance is inversely proportional to the depth of cut, feed and cutting speed and the reductionrates of specific cutting resistance has large values, but the reduction rates are almost constant even though the tool rake angle increase. 3) The batter surface roughness is obtained when the cutting speed and the cutting depth decrease. when the cutting speed is more than 150m/min, a batter surface roughness is obtained. 4) The conditions of optimal machinability for Brass are the true rake angle of about 10˚ and the cutting speed of 200m/min.

판형 열교환기의 열유동 해석

玄淸男,李相勳 홍익대학교 산업기술연구소 2002 産業技術 Vol.12 No.-

In this study, the heat transfer coefficient and heat stress and the flow characteristics according to the shape of pipe interior in Plate Heat Exchanger is studied by a numerical method using Design-Space. One of the most common heat exchangers that is mainly attached in vehicles is studied. Analysis is performed by comparing the results for plate heat exchangers with those for cylinder heat exchangers. In order to increase the effectiveness of heat exchangers, thermal conductiom, material, and thermal stresses in plate heat exchangers are investigated.

축 진직도 측정 및 교정 자동화에 관한 연구

玄淸男,韓仁煥,李英悌 홍익대학교 산업기술연구소 1994 産業技術 Vol.3 No.-

This paper presents an efficient method in automatic measuring of shaft straightness and correcting shafts. During the rotation of a shaft, contact measuring pins touch the shaft to measure runout, and the angle of runout is detected by an encoder. For the correction of runout, a simple rule is developed. The control of correction is achived by the pressing stroke, not by the pressing force. The developed system is to correct runout within the allowable tolerance.

초음파 탐상기를 이용한 재질의 물질특성치 측정에 관한 연구

玄淸男 홍익대학교 산업기술연구소 2000 産業技術 Vol.10 No.-

To determine material properties using a ultrasonic detector is investigated. The procedures are as follows; The first step is to measure speeds for p and sv waves in A1, A2 blocks using a ultrasonic detector. The second step is to determine material properties using the relationship between the wave speeds and the material properties. The experimental data are compared with the standard values. There is good agreement between the two sets of results for A1, A2 bolcks.

Al-7%Zn 합금에 대한 Ti, B 및 Ti-B의 첨가 영향에 관하여

玄淸男 홍익대학교 산업기술연구소 1997 産業技術 Vol.7 No.-

The influence of small amount of Ti B and Ti-B in Al-7% Zn alloy was investigated by means of tensile strength, elongation and micro viker's hardness. The results obtained were as follows: 1. The addtion of a small amount of TiB and Ti-B did not show scarecely and remarkable effect upon the mechanical properties of A7% Zn alloy. Especially, in this alloy, it was found that the worked direction did not effect the mechanical properties at all. 2. The effect of Ti addition on the mechanical properties was more pronounced than of boron or Titanium-Boron.

연삭에서의 접촉길이에 관한 연구

玄淸男 홍익대학교 산업기술연구소 1999 産業技術 Vol.9 No.-

In grinding the contact length between the grinding wheel and the work piece is investigated by using the APS method. The contact length is changed by conditions of cutting, ploughing and rubbing; the results are as follows. 1, Since the whole contact surface is measured in the APS method, the measurement of the contact length is reliable. 2. In grinding the contact length is much greater than the geometrically estimated value. Furthermore the contact length is increased by using the coolant. 3. The contact between the grinding wheel and the work piece is not perfect.

C - Scan을 이용한 시편 내부의 결함 측정 및 탐상 (Ⅱ)

玄淸男,韓材國 弘益大學校 産業技術硏究所 2004 産業技術 Vol.14 No.-

In this study, the flaws in the several test specimens are detected by using a C-Scan system. The following results are obtained through this research; 1. How to detect the flaws in the specimens 2. How to determine the depth of the flaws in the specimens 3. How to determine the size of the flaws in the specimens 4. How to determine if the specimen is in one piece or not and how to detect defects at the joining part 5. Analysis by using Linear Profile and 3D View In order to determine the depth and size of the flaws in the specimens precisely, it is very important to operate the C-Scan system properly

공구 경사각의 변화에 따른 경질재료(SM45C. SM20C)의 절삭특성에 관한 연구

玄淸男 홍익대학교 산업기술연구소 1995 産業技術 Vol.5 No.-

In turing operation it is the material of work piece and cutting tool feed and cutting speed the depth of cut and rake that influence upon the accuracy of demension the manufacturing efficiency the extension of tool life and surface roughness. Especially the identification of cutting force due to the change of tool rake angle which exerts a grate influence on the turning is very important. In this study the cutting force of test materials such as SM45C surface roughness were measured by experiment. And the cutting resistance due to the change of tool rake angle was calculated by applying the three demensional cutting formula then the conditions of optimal machinability were obtained taking into consideration of the material characteristics. From the experimental results the conditions of optimal machinability classified by the test materials are as follows: 1) The normal force action on the tool face has the minimum value at the true rake angle of 5°-10° in SM45c respctively. 2) The speific cutting resisance is inversely proportional to the depth of cut feed and cutting speed and the reduction rates of specific cutting resistance has large values up to the true rake angle of 5°then the decreases when the rake angle increase. 3) The batter surface roughness is obtained when the cutting speed and the cutting depth decrease when the cutting speed is more than 150m/min a batter surface roughness is obtained but the tool life become extremely short due to the increase of tool rake angle. 4) The true rake angle of about 5°and the cutting speed of 150m/min are the conditions for the optimal machinability for SM45C and SM20C.