이상형 스테인레스강의 크롬질화물 석출과 상 방위관계 연구

최병학,김진우,고석민,조용석,김상식,이재현 국립7개대학공동논문집간행위원회 2002 공업기술연구 Vol.2 No.-

Microstructures in the directionally solidified duplex stainless steels were investigated in order to understand the effect of nitrogen addition and its precipitation in the α phase. It was found that the addition of nitrogen causes the formation of fine precipitates in α matrix and segregation phases of nitrogen in the α/γ interface. Both the fine precipitates and the segregation phases were identified as CrN(fcc, a=4.18Å), as a coherent phase related to the α-bcc matrix with crystal relationship of (200) CrN//(01￣1)α and (1￣1￣1)CrN//(3￣2￣1)α.

방향성 응고된 이상형 스테인레스강에서 질소첨가가 미세조직에 미치는 영향

최병학,정병길,김진우,고석민,이재현,김상식,김성준 국립7개대학공동논문집간행위원회 2001 공업기술연구 Vol.1 No.-

Microstructures in the directionally solidified duplex stainless steels were investigated in order to understand the effect of nitrogen addition. It was found that the addition of nitrogen causes formation of fine precipitates in a matrix and segregation phases of nitrogen in the α/γ interface. Both the fine precipitates and the segregation phases were identified CrN(fcc, a=4.16A˚), which has the coherent phase relationship with bcc α matrix of (200) CrN // (0 1￣ 1) α and (1￣1￣ 1) CrN // ( 3￣ 2￣ 1) α.

방전관용 전극개발 및 특성에 관한 연구

안성환,황동원,최준영,송시준,전용우,박원주,이광식 영남대학교 공업기술연구소 2001 工業技術硏究所論文集 Vol.29 No.1

This paper describes the development of sputtered tungsten electrode for discharge tube by making use of Sputtering method using plasma. The Xe discharge tube was designed and fabricated by using sputtered tungsten electrode, and the ICCD(Intensified Charged Coupled Device) and monochromator were used in order to observe the discharge image distribution and to measure the signal intensity. As a result, the emission light form the electrode was spreaded almost uniformly over a wide wavelength band, and the discharge image distribution and the signal intensity show quite a uniform distribution. The emission light from the Xe discharge tube was peaked at 488[nm] and 648[nm].

두가지 혈류 유발방법에 의한 새로운 심폐소생술(이중 혈류 유발 심폐소생술)장치의 개발

황성오,김현,조준휘,오범진,임종천,최경훈,윤정한,이승환,김영식,이강현,이윤선 大韓應急醫學會 1999 대한응급의학회지 Vol.10 No.2

Background: There have been many efforts to augment blood flow during cardiopulmonary resuscitation. These efforts have focused on maximizing the effect of cardiac pump or thoracic pump alone. However, considering that the heart is the biggest blood reservoir and increase of intrathoracic pressure can generate blood flow, simultaneous exploitation of both mechanisms may have synergistic effect. We hypothesized that simultaneous chest constriction in addition to sternal compression by standard CPR may have additive hemodynamic effects by preventing deformation of the chest and increase of intrathoracic pressure. Methods and results: we built a new mechanical device to perform compression and thoracic constriction simultaneously. The device consists of two main elements. Piston in the center is to depress the sternum. Strap is to constrict the thorax circumferentially. Strap is attached to both sides of the piston. When the piston is pushed down, it depresses the sternum and pulls on the thoracic strap. To determine strap width to produce optimal hemodynamic effect, we measured hemodynamic parameters with variable widths of strap in two dogs after induction of ventricular fibrillation. Result of the experiment showed that 10cm wide strap was determined to be most effective. We also determined optimal depth of compression to produce maximal hemodynamic effect with animal experiments using two dogs. Animal experiments showed that the highest aortic pressure could be generated when the stemum was depressed to 5 cm. Cardiopulmonary resusciation using a new device could generate higher systolic aortic pressure, coronary perfusion pressure and end-tidal carbon dioxide tension in comparison with standard cardiopulmonary resuscitation in a pilot animal study using two dogs. Conclusion: New cardiopulmonary resuscitation method using a mechanical device designed by us could perform sternal compression and simultaneous thoracic constriction, and generate better hemodynamic effects than standard cardiopulmonary resuscitation in pilot animal experiments.

포와송 방정식의 해

崔性春,崔玉植 嶺南大學校 基礎科學硏究所 1995 基礎科學硏究 Vol.15 No.-

It is shown that the solution of the simple electrostatic potential 1/r has the first and second derivatives and satisfies Poisson's equation.

폐좌상시 폐단락률과 PEEP치료의 효과

김영식,황성오,최경훈,안무업,오중환,임경수,윤정환,강성준 大韓應急醫學會 1992 대한응급의학회지 Vol.3 No.1

To evaluate the physiologic extent of pulmonary contusion and effect of PEEP therapy for pulmonary contusion, we studied 16 patients received PEEP therapy with pulmonary contusion from nonpenetrating chest trauma. Hemodynamic parameters including pulmonary vascular resistance index and intrapulmonary shunt fraction were calculated from standard measurement, and arterial oxygen tension was measured. Pulmonary vascular resistance index and intrapulmonary shunt fraction were increased in patient group. Arterial oxygen tension was decreased with increase of the intrapulmonary shunt fraction(R=0.75). Arter minimal PEEP therap(5-10 ㎝H₂O), pulmonary vascular resistance index was remained unchanged and intrapulmonary shunt fraction was decreased without significant changes of pulmonary hemodynamics. Increment of arterial tension was increased with decrease of intrapulmonary shunt fraction(R=0.43). Decreased stroke volume index suggested of cardiac injury such as cardiac contusion in patient group. These results of our study suggested that increased intrapulmonary shunt fraction caused arterial hypoxia in pulmonary contusion and arterial oxygen tension was increased as a result of reduced intrapulmonary shunt by PEEP therapy.

심초음파로 결정된 응급 심낭천자술의 천자부위

김성환,황성오,이강현,조준휘,강구현,문중범,이승환,윤정한,최경훈,김영식 대한응급의학회 2000 대한응급의학회지 Vol.11 No.3

Background: The aim of this study was to determine whether the conventional subcostal approach is suitable for emergency pericardiocentesis in patients with cardiac tamponade or impending cardiac tamponade. Methods: This study was a prospective, observational study conducted at the emergency department of a tertiary hospital, Patients who had symptomatic pericardial effusion and who needed emergency pericardiocentesis in the emergency department were included in this study. We measured the epicardium-to-pericardium distance at the subcostal, parasternal, and apical area with two-dimensional echocardiography to determine the appropriate puncture site for pericardiocentesis. An epicardium-to-pericardium distance of more than 1.0 cm was considered as the primary safety factor in determining the Puncture site for pericardiocentesis. The skin-to-pericardium distance was considered as secondary safety factor. Results: Ninety-five consecutive patients(55 males and 40 females; total mean age: 53 year old) with cardiac tamponade or impending cardiac tamponade were enrolled in this study. The puncture site for pericardiocentesis, as determined by echocardiography, was the subcostal area in 43 patients(45%), the apical area in 40 patients(42%), the left parasternal area In 11 patients(12%), and the right parastemal area in one patient(1%). Pericardiocentesis failed in 2 patients(2%) with the subcostal approach and in one patient(1%) with the apical approach. The average epicardium-to-pericardium distance was 31 ±21 mm in patients with the subcostal approach and 21±8 mm in patients with other approaches. There were no differences in the amount of pericardial fluid and in the intraperical pressure among patient groups according to puncture site. There were two procedure related complications: a puncture of the right ventricle with the subcostal approach and a ventricular tachycardia with the apical approach.

원주지역에서 발생한 비외상성 심정지의 일주변화

박금수,김영식,이진응,임종천,이강현,임경수,황성오,최경훈 대한응급의학회 1995 대한응급의학회지 Vol.6 No.2

To estimate the quality of the emergency medical services system of Wonju City, we studied the diurnal variations of 179 non-traumatic cardiac arrest victims who received cardiopulmonary reuscitation at the emergency center of Wonju Christian Hospital. Diurnal variations of non-traumatic cardiac arrest patients were as follows ; The occurence of cardiac arrest at day-time was higher than night-time; 18 cases (11%) from midnight to AM 4, 25 cases (14%) from AM 4 to AM 8, 42 cases (24%) from AM 8 to AM 12, 46 cases (25%) from AM 12 to PM 4, 35 cases (19%) from PM 4 to PM 8, 13 cases (7%) from PM 8 to midnight. Witness cardiac arrest was increased more during the day than night ; 40% from midnight to AM 4, 48% from AM 4 to AM 8, 57% from AM 8 to AM 12.52% from AM 12 to PM 4, 60% from PM 4 to PM 8, 38% from PM 8 to midnight. The transportation time at night-time cardiac arrest was more longer than day-time cardiac arrest ; 30±12mins from midnight to AM 4, 26±9mins from AM 4 to AM 8, 27±12mins AM 8 to Am 12, 25±11mins from AM 12 to PM 4, 25±9mins from PM 4 to PM 8, 35±15mins from PM 8 to midnight. The rate of restoration of spontaneous circulation(ROSC) in day-time cardiac arrest was higher than the night-time cardiac arrest ; 30% from midnight to AM 4, 36% from AM 4 to AM 8, 32% AM 8 to AM 12, 44% from AM 12 to PM 4, 41% from PM 4 to PM 8, 15% from PM 8 to midnight. The survival rate of cardiac arrest has been correlated with collapse time, early bystander CPR, early advanced care. To improve outcome for prehospital cardiac arrest, we concluded that early bystander CPR, and early advanced life support should be performed at the scene and during the transportation especially at night.

심폐소생술중 심실기능 및 판막운동의 평가

이부수,김영식,이강현,황성오,임경수,박금수,윤정한,안무업,최경훈 대한응급의학회 1994 대한응급의학회지 Vol.5 No.2

Background : Mechanism of blood flow during cardiopulmonary resuscitation(CPR) in humans remains controversial and poorly understood, although cardiac or thoracic pump theory was proposed. We investigated cardiac movement, ventricular function and atrioventricular valve motion with aid of transesophageal echocardiography during precordial compression during CPR in humans. Methods and results : During CPR transesophageal echocardiography was performed in 14 patients with non-traumatic cardiac arrest. Manual precordial compression during CPR was performed according to American Heart Association guidelines. Mitral valve closed in 9 and did not close in 5 patients during "compression systole". Tricuspid valve closed during compression systole. Compression vector directed to right ventricle, basal portion of interventricular septum and left atrium. The heart rotated clockwise and the apex was more displaced than the base("swing motion"). Fractional shortening(FS) and ejection fraction(EF) of right ventricle exceeded those of left ventricle(FS : 55±9% vs 18±8%, p<0.05), EF : 79±9% vs 37±16%, p<0.05). FS and EF of left ventricle was higher in patients with systolic mitral valve closure than patients with persistent systolic opening of mitral valve(FS : 21±7 vs 13±7%, EF : 45±12 vs 22±12%, p<0.05), but FS and EF of right ventricle was not different. Conclusion : During precordial compression, the heart rotated clockwise and displaced. Systolic function of right ventricle exceeded left ventricle. Marked compression of right ventricle and systolic closure of tricuspid valve suggested that right ventricle functioned as a pump generating blood flow during precordial compression. Closure of mitral valve was dependant on systolic function of the left ventricle.

백서 Paraquat 두여에 의한 간과 폐 조직의 산화성 손상에서 Vitamin C와 Deferoxamine의 항산화 효과에 관한 연구

정연권,서길준,정중식,정성은,최국진,윤여규 대한응급의학회 2000 대한응급의학회지 Vol.11 No.4

Background: The toxicity of paraquat has been known to be caused by oxygen free radicals which leads to the lipid peroxidation and multiple organ failure. Although vitamin C has been known to be a potent antioxidant, recently there are numerous data which have shown that a low dose of vitamin C may act as a prooxidant due to the stimulation of the Fenton reaction with metal ions, which produces hydroxyl radicals. It has been reported that a deferoxamine in paraquat intoxication could reduce the production of the hydroxyl radicals by the inhibition of the Fenton reaction through the reduction of iron ion in tissue. The aim of this study was to evaluate the effect of the high and low dose of vitamin C and deferoxamine on lipid peroxidation and plasma TNF-α in paraquat intoxication. Methods: Female Sprague -Dawley rats were divided into seven groups: control group which was not given paraquat(20 mg/kg), P group which was given paraquat only, PVH group given paraquat and high dose of vitamin C(100 mg/kg), PVL group given paraquat and low dose of vitamin C(10 mg/kg), PVHD given paraquat, high dose of vitamine C and deferoxamine(100 mg/kg), PVLD given paraquat, low dose of vitamin C and deferoxamine, and PD given paraquat and deferoxamine. Animals were killed at 6 and 24 hours after treatment. Malondialdehyde(MDA), superoxide dismutase(SOD) and glutathione(GSH) contents, catalase activity, plasma TNF-α, and histologic changes in the lung and liver tissue were measured. Results: The lung histology in the PVH and PD or PVHD groups showed the significant decreases in the alveolar edema and interstitial thickness compared to the P group. The liver histololgy in the PVH and PVHD groups demonstrated marked differences in the central venous and sinusoidal dilatation compared to that of the P group. While the MDA levels of the lung and liver in the PVH and PD groups showed the significant reduction compared to that of the P group at 6 hours after treatment, all groups showed the significant changes compared to the P group at 24 hours. There was no significant change of the SOD levels of the lung and liver at 6 hours among all groups. At 24 hours, the SOD levels of the lung in PVH, PVL, and PVHD groups showed the significant increases compared to the P group. The increase of the SOD level in groups combined with deferoxamine, however, revealed a little reduction. The SOD level of the liver in PVH group only significantly increased compared to the P group at 24 hours. There was no significant change of the GSH level of the lung and liver among all groups at 6 hours. At 24 hours, the GSH level of the lung and liver were significantly increased in both PVH and PD group and PVH group, respectively, compared to the P group. Although the catalase activity of the lung was not significantly increased, that of liver was signiflcantly increased in both PVHD and PD groups compared to the P group at 6 hours. The catalase activities of the lung and liver were significantly increased in PVH, PD, and PVHD at 24 hours. The concentrations of the plasma TNF-α were slightly decreased at 6 hours and slightly increased at 24 hours compared to that of the P group, but they were not significant. Conclusion: This study showed that although the low dose of vitamin C had no effect, the high dose of vitamin C revealed a decrease of the MDA level and an increase of SOD, GSH, and catalase activity in the lung and liver tissues, and the effect of the high dose of vitamin C increased with time. The administration of the deferoxamine with or without high dose of vitamin C, however, significantly showed the inhibition of the lipid peroxidation and antioxidant effect and low dose vitamin C decreased the effect of deferoxamine. The effects of the vitamin C and deferoxamine on plasma TNP-α were not clearly shown.