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Mg₂Cu 수소저장합금의 thermal cycling 효과에 관한 연구
한정섭(Jeong Seb Han) 한국수소및신에너지학회 1990 한국수소 및 신에너지학회논문집 Vol.2 No.1
The effect of thermal cycling on the hydrogenation characteristics of the Mg₂Cu-H system was investigated in order to study of intrinsic degradation of the system. The hydrogen storage capacity decreased with thermal cycling from 573˚K to 663˚K. By the thermal analysis it is found that stable MgH₂ hydride is formed during thermal cycling. With a heat treatment at 698˚K at a hydrogen pressure of 16 atm, the hydrogenation rate drastically decreased. From these observation, it isuggested that the intrinsic degradation of Mg₂Cu system results from mainly the formation of stable MgH₂ hydride phase.
한정섭(JEONG-SEB HAN),박진환(JIN-HWAN PARK) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.2
The application of infrared thermography for detecting defects under the surface of a material was studied. Defects in a specimen were made by back-drilled circular holes. To get alarge temperature difference at the surface, a halogen lamp was used for surface heating. We confirmed that the defect location had a good relationship with the maximum temperature difference. The sizes of the defects could be calculated by means of the FWHM. The value of the FWHM of a temperature difference decreased with time. Therefore in an extremely short time after the heating, the true defect size could be measured.
Sievert`s type 자동장치에 의한 마그네슘 수소화합물의 열분석
한정섭 ( Jeong Seb Han ),박경덕 ( Kyung Duck Park ) 대한금속·재료학회 2010 대한금속·재료학회지 Vol.48 No.12
In order to apply the Sievert`s type automatic apparatus to thermal analysis of hydrogen absorbing materials, the dehydrogenation of the Mg-H system was investigated. As the initial wt% of hydrogen was increased to 4.4, the peak temperature of evolution rate shifted to higher temperature. However, with the initial wt% of hydrogen higher than 4.4, peak temperature of evolution rate did not change. The peak temperatures of evolution rate obtained by automatic apparatus were almost the same as those measured by a manual apparatus. As the heating rate was increased, the peak temperatures increased; the peak temperatures for heating rates 1, 2 and 3 K/min were 664, 687 and 702 K, respectively. The activation energy for the decomposition of Mg hydride was 101 kJ/mol. The Sievert`s type automatic apparatus can be successively applied to the thermal analysis of metal hydride.
한정섭(Jeong-Seb Han) 동아대학교 해양자원연구소 2007 동아대학교 해양자원연구소 연구논문집 Vol.19 No.-
In order to measure the extent of corrosion of rebar in the concrete, two types of arrangement of the wenner probe to rebar was used. The concrete was corroded in the 3 % NaCl solution. In case of shallow depth compare to cover depth, the electrical resistivity of parallel arrangement of wenner probe is higher than that of normal arrangement. This is thought to be related with the size of specimen. The electrical resistivity is same about 0.6 ㎝ ahead of rebar when two types of arrangement of the wenner probe to rebar is used. With the extent of corrosion the electrical resistivity was decreased.
열화상 기술에 의한 M.C 나일론의 내부 결함에 대한 평가
한정섭(Jeong-Seb Han) 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.2
Infrared thermography was used to determine the location, size, and depth of defects under the surface of M.C nylon. Defects were created in a specimen by back-drilling circular holse. These defects were located at the maximum temperature difference that occurred. The size of the defects could be calculated by means of the full width at half of the maximum temperature difference. The depth of a defect could be calculated by the peak time and the maximum temperature difference. The maximum temperature difference between a defect and normal part was decreased with the depth of the defect. And the peak time also slowly appeared with the depth of the defect.
한정섭(Han Jeong-Seb) 동아대학교 해양자원연구소 1998 동아대학교 해양자원연구소 연구논문집 Vol.11 No.-
To make iso-poential map and automatically analyze the corrosion of rebar with the scattered data, a program is developed using Visual Basic 5.0.<BR> Rectangle search is designed to calculate a grid potential with scattered input data. It is shown that according to how many input data is used to calculate a grid potential, the iso-potential map is changed. Comparing to commercial program the developed program is proved and it is also shown that it can make more accurate iso-potential map. Using the developed program, user can make iso-potential map and analyze without grid potential. And to measure grid potential they do"nt need to draw grid on the wall.
한정섭(Jeong-Seb Han) 동아대학교 해양자원연구소 2007 동아대학교 해양자원연구소 연구논문집 Vol.19 No.-
The fabricability, good corrosion resistance and high thermal conductivity of aluminum brass (Al-brass) material has made it widely used in heating coil units of crude oil carrier vessels. But because of bad brazing technique, unexpected leakage some times occurred. To know the exact bonding state, the ultrasonic and X-ray test of tube which was brazed were done. The ultrasonic test is not a good method to know brazing state of tube. By the X-ray test, it is recognized that to know the exact brazing state of Al-brass tube is possible. And a new heating method of brazing should be developed to get a good bonding state.
한정섭(Han Jeong-Seb) 동아대학교 해양자원연구소 2003 동아대학교 해양자원연구소 연구논문집 Vol.15 No.-
To detect surface corrosions of steel plate, Infrared camera was used. The steel plate was coated with uretan resin formulated with Strontium Chromate(STC). The test specimen were immersed in 0.5M NaCl-solution with 10 mV during 6 month. To detect coating surface corrosions, the plate was slightly heated. Delaminated blister, blister and filiform corrosion are clearly detected with infrared camera. According to a kind of corrosion, the temperature of steel plate are different. The greater the diameter of blister, the higher the temperature of center of blister.
한정섭(Jeong Seb Han) 동아대학교 해양자원연구소 2006 동아대학교 해양자원연구소 연구논문집 Vol.18 No.-
To modify the crack model developed by Wilkinson and Vitek, the concentration of hydrogen ahead of crack tip was calculated by numerical method. Backward Time, Centered-Time method was adopted. The concentration of hydrogen ahead of crack tip was varied with initial hydrogen concentration, the coefficient of diffusion of hydrogen and the strength of materials. The coefficient of diffusion of hydrogen has more effect than initial concentration of hydrogen on the saturation time in the elastic region. The higher the strength of materials, the greater the concentration of hydrogen.
적외선 카메라를 이용한 염분에 의한 철근 부식에 관한 연구
한정섭(Jeong Seb Han),이상호(Sang Ho Lee) 동아대학교 해양자원연구소 2006 동아대학교 해양자원연구소 연구논문집 Vol.18 No.-
In order to measure the extent of corrosion of rebar in the concrete, infrared thermography method was applied. The concrete was corroded in the 3 % NaCl solution. To get the difference of temperature of the concrete, surface heating was adopted. According to the extent of corrosion, peak temperature comparing to around position was formed. This is the reason that the crack of concrete formed by corrosion affected the decrease of temperature. This result shows that using the data accumulated, the extent of corrosion of rebar can be measured by infrared thermography method.