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파이버 레이저의 스테인리스강 용접시 인프로세스 모니터링을 위한 유기 플라즈마와 방사신호간의 상관성 연구(II) - 후판 용접시 측정신호의 특성 변화 -
이창제,김종도,Lee, Chang-Je,Kim, Jong-Do 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.6
On this study, we researched the in-process monitoring during fiber laser welding as well as on the first paper. On the previous/formal study, we analyzed the change of emission signal on thin plate welding. On this study, however, we analyzed RMS and FFT with emission signals in laser welding on lap joint and butt joint of 8mm-thick 316L stainless steel. As the result, the movement of specific frequency peak was observed according to welding speed changes. Furthermore, frequency peak as a result of FFT on the thick plate welding are much clearer than on the thin plate welding. Therefore, it is expected that the welding parameter changes can be predicted in case of applying FFT to in-process monitoring.
이창제,김유찬,김종도,Lee, Chang-Je,Kim, Yu-Chan,Kim, Jong-Do 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.1
Recently, welding technology of nonferrous metals which were difficult to implement by arc welder has become available through digitalization of arc welding machine. Among them, the welding quality improvement of aluminum welding is very noticeable. These results increase the arc stability by controlling arc current and voltage waveform precisely, and control wire feed speed by synchronizing with arc current which the feed rate of filler wire is controlled by a precise motor control of servomotor and not by a simple constant speed feeding. Not only through the hardware digitalization of arc welding machine but also through advance of software of arc welding, it became possible to implement a certain level of welding quality by a simple operation. These led to CMT welding process implementation which requires low heat input than current arc welding and highly increased the applicability of the aluminum welding.
API강재의 파이버레이저 용접시 유기하는 플라즈마의 방사특성 (III) - 보호가스가 플라즈마 방사 신호에 미치는 영향 -
이창제,김종도,김유찬,Lee, Chang-Je,Kim, Jong-Do,Kim, Yu-Chan 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.3
Ar, $N_2$, and He are the conventional kind of shield gas that are used for laser welding. Many researches on the impact of laser welding shield gas have been done, and it is on going until now. However, there are few studies that analyze the changes and differences of the plasma emission signal. Therefore, in this study, we evaluated the change in the penetration characteristics according to the type of shield gas during fiber laser welding impacts to the plasma signal. As a result, if was checked that the difference in molecular weight of Ar, $N_2$, and He affects to the amount of spatter, and also found that the measured plasma radiation signal changes similar to the order of the molecular weight of the gases. Especially, clear change on the signal intensity per each shield gas was measured through RMS, and found that the shield gas was nothing to do with the FFT analyzed result.
이창제(Chang Je Lee),조경래(Gyong Rae Cho),김의간(Uei Kan Kim),김동혁(Dong Hyuk Kim),도덕희(Deog Hee Doh) 한국가시화정보학회 2016 한국가시화정보학회지 Vol.14 No.2
In this study, a Masked Omni-Directional Integration(MODI) method for pressure calculation is proposed using the Particle Image Velocimetry (PIV) data. To obtain the velocity field, the Affine PIV method was adopted. Synthetic images were generated for a solid body rotation. Calculation on the pressure was based on the Navier-Stokes equation. The results obtained by the MODI were compared with those obtained by theoretical pressure and by the Omni-Directional Integration(ODI) method. It was shown that the minimum error by the proposed MODI method was attained when the mask size was 1.
조창제(Chang Je Cho),강성욱(Seong Wook Kang),곽경일(Gyeong Il Kwak),이준호(Joon Ho Lee),김국진(Kuk Jin Kim) 전남대학교 수산과학연구소 2022 수산과학연구소논문집 Vol.31 No.1
Since high-resolution meteorological data can be used for precise research or useful services in real life, the need for high-resolution data production is increasing. Considering the local phenomenon and complex geographical characteristics of the Korean Peninsula, the installation of a large number of observatories is ideal, but this is limited by practical problems such as budget. Numerical models can be a good alternative to this. In this paper, a study was conducted to super-resolution the GDPS data of the 12 km unit grid into the LDPS data of the 1.2 km unit grid through the FSRCNN and VDSR techniques. As the performance evaluation index of the super-resolution model, MAE, which means the average difference between the super-resolution data and the LDPS data, and PSNR, which means the loss rate of the data, were used. As a result, the VDSR model was excellent for temperature and the FSRCNN model was excellent for U and V components for wind.
박창제(Park, Chang-Je),이성진(Lee, Sung-Jin) 한국노년학회 2011 한국노년학 Vol.31 No.3
본 연구는 노인의 장기요양보호서비스 이용 유형별 부양가족의 부양스트레스 경로를 분석하여 그 함의를 논의하는 데 목적이 있다. 조사대상자는 2008년 7월부터 시행되고 있는 노인장기요양제도의 적용 대상자로 인정받은 65세 이상 노인과 그 부양가족이었고, 비확률표집을 통하여 주부양자를 대상으로 방문요양서비스와 노인요양서비스 유형을 구분하여 설문조사하였다. 회수된 설문지 중에서 방문요양 151부, 노인요양시설 107부 총 258부가 본 연구의 분석 표본으로 사용되었다. 분석결과는 다음과 같았다. 첫째, 시설이용 노인은 재가서비스 이용 노인에 비하여 상대적으로 여성비율과 고연령, 사별의 비율이 높고, 자녀수는 많았다. 둘째, 시설이용 노인은 평균적으로 재가서비스이용 노인에 비하여 ADL제한이 심하고 주요 질병으로 치매나 중풍의 비율이 높고 요양등급의 수준이 높았지만 그 반대인 경우도 있었다. 셋째, 재가서비스이용 노인의 주부양자는 시설이용 노인의 주부양자에 비하여 여성, 고연령, 저학력의 비율이 높았고, 관계는 배우자와 며느리의 비율이 높았으며 건강상태가 나쁘고 소득이 낮은 편이었다. 넷째, 장기요양서비스 이용 유형별로 부양자의 스트레스 경로형태에서 차이를 보였다. 즉, 장기요양서비스 유형별로 1차 스트레스 요인이 2차 스트레스요인에 미치는 경로방향이 다르고, 2차 스트레스요인이 우울에 미치는 경로도 다르다. 특히 방문요양 이용 부양자는 자아상실이 우울에 크게 영향을 미치는 경로를 보여주지만 노인요양시설 이용 부양자는 자아상실이 우울에 미치는 경로가 전혀 형성되지 않았다. 다섯째, 부양가족의 스트레스인 우울에 직접 영향을 미치는 스트레스 요인들은 장기요양 서비스 이용 유형별로 차이를 보였다. 즉, 방문요양의 경우엔 2차 스트레스 요인 모두가 직접 영향을 미친 반면, 노인요양시설의 경우엔 2차 스트레스 요인 중 근로갈등과 가족갈등이라는 두 개의 요인은 우울에 직접적인 영향을 미쳤지만, 자아상실은 영향을 미치지 않았다. 따라서 노인 부양가족의 스트레스를 경감시키는 정책이나 프로그램이 장기요양보호서비스 이용유형에 따른 스트레스 요인과 스트레스 경로를 반영하여 다르게 설계되어야 한다는 것을 알 수 있다. The purpose of this study is to analyse the family caregivers' stress pathways by types of long term care services for the elderly, and then to discuss the findings of analysis. For this research, primary caregivers that provide care the elderly requiring long term care services sanctioned by National Health Insurance Corporation were drawn and surveyed. Among collected data, data for 258 primary caregivers by type of long term care services were used for this study. The results of this study can be summarized as follows. First, on average, the elders that utilize care service in institutions for the elderly were higher proportion of women, older, higher rate of bereavement, more children than the elders that utilize in-home care service, but some cases were vice-versa. Second, the elders that utilize care service in institutions more ADL dependency, higher proportion of severe dementia or severe stroke, higher care rank by National Health Insurance Corporation than the elders that utilize in-home care service on average. Third, primary caregivers with elders that utilize in-home care service were higher proportion of women, older, lower education level, higher rate of spouse and daughter-in-law in relationship with care recipient, less health, lower income than primary caregivers with elders that utilize care service in institutions. Fourth, subjective indicators representing caregivers' reactions to caregiving for the elderly significantly impact on caregivers' stress(ie, depression), and pathway of caregivers' stress are differentiated by type of long term care services. Fifth, stressors that have direct impacts on depression as caregiving family are differentiated by type of long term care services. Therefore, policies or programs to reduce negative mental health or stress of caregivig families should be designed differently by reflecting pathway of various stressors and stress by use types of long term care services for the elderly.
API강재의 파이버레이저 용접시 유기되는 플라즈마의 방사특성 (II) -용접조건과 방사신호의 관련성-
이창제,김종도,김유찬,Lee, Chang-Je,Kim, Jong-Do,Kim, Yu-Chan 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.4
Laser welding by fiber laser accompanied by a lot of spatter and humping bead. This is because the deep and narrow keyhole usually form due to high beam quality. So the weld bead is formed defects, because the plasma jet with a high vapor pressure make the molten pool on keyhole wall scattered. For such a reason, unstable behavior of keyhole is difficult to monitor laser welding by using the laser induced plasma. Mostly, fiber laser welding of thick plates most be influenced by this effect. Therefore, fiber laser welding has been difficult to apply the sole. Thus, laser welding monitoring based on plasma measurements have much difficulty in measurements and analysis of signal. In this study, influence of the plasma emission signal according to welding speed and laser power in fiber laser welding analysed by using RMS and FFT analysis. We can verify that RMS value of the plasma emission signal changes with welding parameters in fiber laser welding, and aspect ratio greater than 1, the peak of FFT frequency had been moved in accordance with welding parameter.