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西獨 技術科 敎育課程에 관한 硏究 : 니더작센주와 노르트라인 베스트팔레주를 중심으로
金振淳,韓用萬 충남대학교 공업교육연구소 1988 論文集 Vol.11 No.1
This study investigated the character, objectives, tea¨ching contents and methods of 'Arbeitslehre' at the Lower Saxony and North Rhine Westphalia State in the Federal Republic of Germany. 1. In general the 'Arbeitslehre' is taught in the secondary school as an integrated subject combined work, economy, technology and home economics, because these subjects have some common elements for students to adapt to the future world of work and economy. 2. The objectives of the 'Arbeislehre' is to provide experience and knowledge about fact, structures and conditions of the world of work and economy for the pupils, which help them to find their individual way into their daily and vocational life. 3. Main teaching contents of the 'Arbeitslehre' are 1) the organization and role of enterprise 2) economy and consumption 3) vocational guidance 4) working conditions in the 'work/economy' subject, 1) electricity and electronics 2) machining and manufacturing 3) construction in the 'technology' subject, and 1) organization of household affairs 2) management of domestic econonmy 3) family education in the 'home economics'subject. 4. The distintive fecture of teaching methods is to secure congruence between theory and practice by means of fieldtrip, on-the-job practice, project method, case study, etc.
열복사의 색수차 공간여과를 이용한 레이저 용접 감시기술
김민석,백성훈,박승규,정진만,김철중 한국레이저가공학회 1999 한국레이저가공학회지 Vol.2 No.2
An innovative real-time weld monitoring technique using chromatic filtering of the thermal radiation from a weld pool is developed. This thermal radiation from the weld pool is focused on an aperture and the transmitted thermal radiation is monitored at two wavelengths with high-speed single-element detectors. Due to the chromatic aberration introduced in the focusing optics, the transmittance curve of thermal radiation varies by the wavelength. Owing to this difference in the transmittance, the local variation of thermal radiation from the weld pool can be monitored by processing the two spectroscopic signals from two detectors. In this paper, the algorithms to monitor the laser power on the weld specimen and the focus shift are investigated and the performances of laser power and focus monitoring are shown for a pulsed Nd:YAG laser welding. The monitoring of the weld pool size variation is also discussed.
제4형 가족성 고중성지방혈증 임산부에서 발생한 급성 췌장염 1례
박관응,윤채중,김영학,진영기,윤성호,권용은,김태원,박찬국,김만우 朝鮮大學校 附設 醫學硏究所 1997 The Medical Journal of Chosun University Vol.22 No.2
Plasma levels of cholesterol (TC) and triglyceride(TG) physiologically increase during pregnancy. The lipid increment is 23-53% above the pregravidic level for TC and 2- to 3-fold of the prepregnancy level for TG. If the TC and TG are higher than normal values in pregnancy, the patient must be carefully monitored. Acute pancreatitis is the main consequence of hyperlipidemia and occurs either during pregnancy, in the third trimester, or in the puerperium. Mortality is high both for the mother (21%) and the fetus (20%). We report a case of 28 year-old pregnant woman at 29 weeks gestation with hypercholesterolemia (TC = 357 ㎎/dl) and severe hypertriglyceridemia (TG = 1300 ㎎/dl). The patient was admitted to the hospital because of severe epigastric pain, nausea and vomiting. Total serum cholesterol was increased and trigyleride was markedly increased. The electroporesis pattern of serum lipoprotein showed increase in pre-beta lipoprotein fraction, suggesting IV hypertriglyceridemia pattern. According to a review of the literature, the incidence of pancreatitis during pregnancy is 1 in 1000 to 3000 pregnancies. Severe hypertriglyceridemia in pregnancy should be treated with a careful restriction of calories and fat: for preventing acute pancreatitis, hospitalization for intravenous fluid therapy and plasma exchange must be required.
트리아릴포스포늄 염과 카르보닐 화합물 사이의 위티그 반응의 입체선택성에 대한 고압 효과
김정성,최정훈,지진영,김창만,김용훈 대구대학교 기초과학연구소 1999 基礎科學硏究 Vol.15 No.3
The Wittig reactions of triarylphosphonium ylides with various carbonyl compounds under high pressure were carried out to investigate its effect on the cis-trans stereochemical outcome. Generally, the cis-stereoselectivities at atmospheric pressure are known to be resulted from smaller steric hindrance of α-carbon of carbonyl group with hydrogens of phenyl residue of triphenylphosphonium ylide and in oxaphosphetane intermediate stage. Thus, the steric interactions between triphenylphosphonium ylide and carbonyl compounds in the transition state can be maximized. And, the reactions of semistabilized ylide and stabilized ylide at atmospheric pressure generate mainly thermodynamically more stable trans-alkane after formation of betaine intermediate. The reactions at high pressure, however, can generate cis-alkene more exclusively through oxaphosphentane intermediate,directly without the formation of betaine intermediate by reducing distance between ylide and carbonyl compound. Reaction between benzyl triphenylphosphonium ylide, a semistabilized ylide, and butyraldehyde at atmospheric pressure gave cis-1-phenyl-1-pentene with 34/66 of Z/E stereoselectivity, but when pressurized at 10000 bar, cis-alkene with 69/31 the Z/E ratio was excellently yielded than trans-alkene. In the case of Wittig reaction of ethoxyacetyl triphenylphosphonium ylide, a stabilized ylide, with butyraldehyde, Z/E stereoselectivity at 10000 bar was inversed in contrast to atmospheric pressure.
Kim, Do-Hyung,Chung, Chin-Man,Baik, Sung-Hoon,Kim, Koung-Suk,Kim, Jin-Tae The Korean Society for Nondestructive Testing 2008 한국비파괴검사학회지 Vol.28 No.4
We report experimental results on the correlations between welding penetration depth and the frequencies of the radiation from the welding pool. Various welding samples such as SUS304, brass, SUS316, etc. have been investigated with 2 kW CW Nd:YAG laser welding machine. The radiation signals from the plume generated by the interactions between the welding sample and laser with respect to the defocusing length was measured with fiber system collecting the plume signal. Analysis of the frequencies by using fast Fourier transform (FFT) shows that the penetration depth is deep as plume signal frequencies are low, shallow penetration depth for high frequencies. Frequencies up to 250 Hz for obtained signals can be analyzed with the discrete FFT. This is the useful method fur closed loop control of the laser power with respect to the welding penetration depth and is used for real time inspection of the welding quality.
Auto-focus Control by Chromatic Filtering in Laser Welding
Kim, Cheol-Jung,Baik, Sung-Hoon,Kim, Min-Suk,Chung, Chin-Man,Kim, Kwang-Jung Optical Society of Korea 2000 Current Optics and Photonics Vol.4 No.2
Optical monitoring using the chromatic aberration of focusing optics is applied to auto-focus control in laser welding. The spectral transmittance of thermal radiation from a weld pool through an aperture depends on the wavelength of the spectral band and on the distance of the weld pool from the focusing optics. Its dependence has been used to monitor the focus shift in laser welding by measuring the spectral band signals filtered by the aperture. The difference between pulsed and continuous laser welding is analyzed. Furthermore, the dependence of the focus shift monitoring on the weld pool size variation is optimized to monitor the focus shift independently from the laser power change at the weld pool. The performance of the auto-focus control with chromatic filtering is presented for pulsed laser welding.