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해양환경 중 음극전류 프로세스에 의해 강판에 형성된 석회질 피막의 특성 분석
박준무(Jun-Mu Park),강재욱(Jae Wook Kang),최인혜(In-Hye Choi),이승효(Seung-Hyo Lee),문경만(Kyung-Man Moon),이명훈(Myeong-Hoon Lee) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.2
Cathodic protection is widely recognized as the most cost effective and technically appropriate corrosion prevention methodology for the port, offshore structures, ships. When applying the cathodic protection method to metal facilities in seawater, on the surface of the metal facilities a compound of calcium carbonate(CaCO₃) or magnesium hydroxide(Mg(OH)₂) films are formed by Ca<SUP>2+</SUP> and Mg<SUP>2+</SUP> ions among the many ionic components dissolving in the seawater. And calcareous deposit films such as CaCO₃ and Mg(OH)₂ etc. are formed by the surface of the steel product. These calcareous deposit film functions as a barrier against the corrosive environment, leading to a decrease in current demand. On the other hand, the general calcareous deposit film is a compound like ceramics. Therefore, there may be some problems such as weaker adhesive power and the longer time of film formation uniting with the base metal. In this study, we tried to determine and control the optimal condition through applying the principle of cathodic current process to form calcareous deposit film of uniform and compact on steel plate. The quantity of precipitates was analyzed, and both the morphology, component and crystal structure were analyzed as well through SEM, EDS and XRD. And based on the previous analysis, it was elucidated mechanism of calcareous deposit film formed in the sacrificial anode type (Al, Zn) and current density (1, 3, 5 A/㎡) conditions. In addition, the taping test was performed to evaluate the adhesion.
문경만(Kyung-Man Moon),정재현(Jae-Hyun Jeong),박준무(Jun-Mu Park),이명훈(Myeong-Hoon Lee),백태실(Tae-Sil Baek) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.6
Many surface protection methods have been developed to apply to constructional steels which have been used under severe corrosive environments. One of these methods, hot dip galvanizing is being widely used to the numerous constructional steels such as a guard rail of high way, various types of structural steel for manufacturing ship and for some other industrial fields etc.. Recently, the cost of zinc is getting higher and higher, thus, it is considered that improvement of hot dip galvanizing process to reduce the cost of production should be developed possibly. In this study, additives such as acid cleaning solution, NH₄OH, Al(OH)₃ and H₂O₂ were added to flux solution, and omission of water washing treatment after acid cleaning was investigated with some types of flux solutions added with some additives mentioned above. The decrement of pH by adding the acid cleaning solution could be controlled due to neutralization reaction with addition of NH₄OH. The flux solution added with both NH₄OH and Al(OH)₃ exhibited nearly the same color and pH value as those of orignal flux solution with no added, and the sample dipped to the flux solution which was added with additives mentioned above indicated a relatively good corrosion resistance compared to other samples. However, the flux solution added with NH₄OH, Al(OH)₃ and H₂O₂ exhibited a different color, sediment and a bad corrosion resistance. Consequently, it is considered that omission of water washing treatment may be able to perform by adding optimum additives to the original flux solution.
PVD법에 의해 제작한 Al-Mg 코팅 강판의 내식성에 미치는 Mg 함량 및 열처리의 영향
강재욱(Jae Wook Kang),박준무(Jun-Mu Park),황성화(Sung-Hwa Hwang),이승효(Seung-Hyo Lee),문경만(Kyung-Man Moon),이명훈(Myeong-Hoon Lee) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.2
This study was intended to investigate the effect of the amount of magnesium addition and heat treatment in the Al-Mg coating film in order to improve corrosion resistance of aluminum coating. Al-Mg alloy films were deposited on cold rolled steel by physical vapor deposition sputtering method. Heat treatment was fulfilled in an nitrogen atmosphere at the temperature of 400°C for 10 min. The morphology was observed by SEM, component and phase of the deposited films were investigated by using GDLS and XRD, respectively. The corrosion behaviors of Al-Mg films were estimated by exposing salt spray test at 5 wt.% NaCl solution and measuring polarization curves in deaerated 3 wt.% NaCl solution. With the increase of magnesium content, the morphology of the deposited Al-Mg films changed from columnar to featureless structure and particle size was became fine. The x-ray diffraction data for deposited Al-Mg films showed only pure Al peaks. However, Al-Mg alloy peaks such as Al₃Mg₂ and Al12Mg17 were formed after heat treatment. All the sputtered Al-Mg films obviously showed good corrosion resistance compared with aluminum and zinc films. And corrosion resistance of Al-Mg film was increased after heat treatment.
성인 환자의 전신 마취동안 사용되는 O2 와 N2O 의 적정유량
박대팔,구본업,서일숙,박세훈,박준만,손기석,김세연,이병용 대한마취과학회 1996 Korean Journal of Anesthesiology Vol.31 No.2
Background: During adult general anesthesia, we used 3~5 L/min of fresh gas flow(FGF) but low FGF are employed, the amount of anesthetic consumption and air contamination can be reduced. The aim of this study was to determine the minimal appropriate inflow rate of oxygen and nitrous oxide during semiclosed circle technique. Methods: We selected 40 patients, ASA group l or 2, scheduled for elective, nonabdominal surgery under general anesthesia with semiclosed circle system. Anesthesia was maintained with 50% oxygen, nitrous oxide and enflurane, controlled ventilation was used; rate of 10/min, tidal volume of 10 ml/kg. After induction and vital signs stabilized, FGF was changed to 4 L, 3 L, 2 L and 1L/min at interva1 of 30 minutes. We observed mean airway pressure and arterial blood gas tensions. Results: The changes of mean airway pressure did not correlated with fresh gas inflow rate. In arterial blood gas analysis, PaO showed a decreasing tendency significantly according to decreasing fresh gas inflow rate(p$lt;0.01) but there were no clinical hypoxemia in all patients. There were no significant changes in pH, PaCO₂ and base excess. Conclusions: We consider that FGF of 1-2 L/min is appropriate during adult general anesthesia because of economic and ecological advantages. Also, we consider low flow technique with below 1L/min can be used safely and effectively under proper gas monitoring such as oxygen analyzer capnometer.
전재규,지대림,김성기,박준만 대한마취과학회 1997 Korean Journal of Anesthesiology Vol.33 No.6
Background: This study examined hemodynamic variables, oxygen delivery, extraction, and consumption in response to acute progressive hypoxia and hypercarbia in the setting of apnea. Methods : Apnea was induced in 9 healthy mongrel dogs by disconnecting animals from mechanical ventilation of 30 minutes with pure oxygen. Hemodynamic variables, oxygen transport, extraction, and consumption were rapidly and repeatedly measured using pulmonary arterial and arterial catheters until cardiac output was undetectable. Results : The baseline PaO2, PaCO2, pH, base excess were 318±137 mm Hg, 36±3.5 mm Hg, 7.30±0.06, 6.81±2.65 mmol/l respectively. Hypercarbia and hypoxemia(76±33 mm Hg) was first noted at 1 and 4 minute respectively. Base excess was not changed. Indices of preload(PCWP and CVP) were increased early in the time course(P<0.05). In contrast, indices of afterload(SVR) increased later, just before cardiac decompensation began(P<0.05). No significant reduction of cardiac output, oxygen delivery, extractd consumption was detected just until abrupt cardiac decompensation started, 5 minute. Conclusions : These data suggest that the early increase in preload was primarily due to hypercarbia whereas the late increase in afterload was due to hypoxemia, but the main cause of acute cardiac decompensation was a critical decrease in arterial oxygen tension with some contribution of increased preload and afterload. (Korean J Anesthesiol 1997; 33: 1020∼1028)