Mo¨ssbauer Parameters of Fast Neutron-irradiated Nuclear Pressure Vessels at Room- and Liquid nitrogen-temperature

이용곤,김형상,홍치유,유연봉 동국대학교 자연과학연구원 2000 자연과학연구 논문집 Vol.5 No.-

The embrittlement of fast neutron-irradiated reactor pressure vessel (RPV) steels was investigated by X-ray diffraction patterns at room temperature and Mo¨ssbauer spectroscopy at room- and liquid nitrogen-temperature. Neutron fluence on the samples were 1012, 1013, 1014, 1015, 1016, 1017, 1018n/cm². The X-ray diffraction patterns at room temperature showed that the structure of neutron unirradiated sample was bcc type, where as but the neutron irradiated samples with the fluence higher than 1017 n/cm² were so severely damaged, that bcc type structure disappeared. The Mo¨ssbauer spectra of all samples showed superposition of two or more sextets. In this paper all Mo¨ssbauer spectra were fitted by three set of sextet. The isomer shift and quadrupole splitting values were found around zero. At liquid nitrogen temperature, magnetic hyperfine field increase rapidly to 480 ∼ 552 kOe at S1 sextet in the samples of 1017∼1018n/cm² neutron fluences. And room temperature, magnetic hyperfine field also increased rapidly to 480 ∼507 kOe at S1 sextet in the samples of 1017∼1018n/cm²neutron fluences. This rapid increase of magnetic hyperfine field was infered to be caused by the change of 56Fe, 55Mn into 57Fe by neutron irradiation.

응급의료 헬리콥터를 이용한 환자이송에 대한 고찰

송형곤,김병철,송근정,정연권,신백효 大韓應急醫學會 1998 대한응급의학회지 Vol.9 No.4

Background: The first EMS helicopter was introduced to Korea in 1996 and from Dec. 1. 1997, it was used for transporting emergent patients. Authors, here upon, report the transporting experiences. Methods: From Dec. 1, 1996 to Dec. 31, 1997, Samsung Medical Center's EMS helicopter was used for air evacuation of critically ill patients. The patients data prospectively analyzed. Result: A total of 65 patients were transported. Male to female ratio was 1.95:1. The mean transport time was 64.1 min(10 - 160 min). Majority of the evacuated patients was surgical patients (General Surgery : 16, Orthopedic surgery : 10, Neurosurgery : 6, Internal medicine : 13, Pediatrics : 3, and others : 3). Twenty-one of the 65 patients transported were admitted to ICU and 31 did not require ICU care. During the air evacuation, one physician and one nurse trained for air evacuation attended the patients. No medical problems or deaths developed during the air evacuation period. Conclusion: The first EMS helicopter was introduced to Korea in 1996. From Dec. 1, 1996 to Dec. 31, 1997, Samsung Medical Center's EMS helicopter was used for air evacuation of critically ill patients. The patients data reported.

아급성기 대량 재해 지역에서의 의료 지원 : '99 대만 지진 의료 지원을 중심으로

송형곤,강보승,송근정,정연권 대한응급의학회 2000 대한응급의학회지 Vol.11 No.3

Background: There was a powerful earthquaken(Richter Scale 7.6) In Tiawan, on Sep.21, 1999. We supported the organized medic긴 services in that area during 5 days. Methods: We made the protocol and analyzed the results prospectively. Results: We took care of a total of 708 patients from sep. 23 to sep. 27. Traumatized patients related to the earthquake were 245(34.6%), and most of them had minor injuries. Two hundred thirty-nine(239, 33.8%) patients visited us for medical disease related to living in a group. There were 29(4.1%) patients who complained of neuropsychiatric problems due to the post-earthquaken stress. Because the condition of the patients was so bad, 18(2.5%) were transferred to receive more medical services. Conclusion: In disaster area, organized medical services have two different roles, especially in the subacute stage. One is responsibility for real emergency medical care, and the other is medical care of non-emergency patients.

정상 분만 후 발생한 대동맥 박리증

심민섭,송형곤,정연권,송근정 대한응급의학회 2000 대한응급의학회지 Vol.11 No.4

Hypertension is a risk factor for developing fatal aortic dissection. Aortic dissection occurs 2~3 times as often in men than in women between ages of 50~70 years old. Among other risk factors, aortic dissection occurs especially in women below the age of 40 years old in pregnancy-related cases. In pregnancy-related cases, aortic dissection occurs n the third trimester and in puerperium, as well as in multiparous women. The writers experienced an aortic dissection related pregnancy. The patient was 32 years old, diagnosis of dissection occurred in the postpartum period. Although, aortic dissection is a rare complication of pregnancy, the knowledge of this may assist the emergency physician save the lives of patients.

강산 및 강알칼리 음독에서 냉각 용액을 사용한 희석 요법과 중화 요법의 가능성

이중의,송형곤,김동훈,권운용,곽영호,서길준,윤여규 대한응급의학회 2001 대한응급의학회지 Vol.12 No.3

Background: There is no effective treatment modality for caustic agent ingestion. Dilution and neutralization are prohibited because of the risk of secondary thermal injury. This experiment is designed to evaluate the amount of dilution and neutralization heat and to gauge the applicability of dilution and neutralization therapy using cold solutions to suppress the peak temperature. Methods: This is an in-vitro chemical experiment. HCl, CH3COOH, NaOH, and NH4OH are selected as representatives of strong and weak acids and strong and weak alkali, respectively. 20℃, 11.6M, 5.8M, and 2.9M solutions of each acid and alkali are made and mixed using a magnetic stirrer at a room air temperature of 28℃. The peak temperature, the duration above 40℃, and the heat amount are measured or calculated. Results: When a 11.6M HCl or NaOH solution is diluted with same amount of water, 32 or 18cal. per mL of HCl or NaOH is produced, respectively. HCl produces a significant peak temperature, but NaOH does not. The lower the concentration, the lower the amount of heat production. 11.6M CH3COOH and NH4OH solutions don't produce dilution heat.11.6M and 5.8M solutions of all acids and alkali produce destructive neutralization heat. However, 2.9M solutions produce neutralization heat which might be controllable. When a 11.6M HCl or NaOH solution is neutralized with a -10℃ 2.9 M NaOH or HCl solution, respectively, the peak temperature produced is below 40℃ and seems to add little thermal damage to viable tissue. Conclusion: Dilution and neutralization with a cold solution in cases of strong acid or alkali ingestion is a promising method to avoid thermal injury.

'퇴원설명문'에 의한 72시간내 부적절한 응급센터 재방문의 감소

박하영,심민섭,송형곤,송근정 한국의료QA학회 2005 한국의료질향상학회지 Vol.12 No.1

Background : Patients who were discharged from the emergency department(ED) may revisit. These patients are divided into two groups; one is expected scheduled condition, the other is unexpected condition. These patients of inappropriate revisits to the ED would be unsatisfied, difficult to make rapport and take legal action as a result of additional medical charges. The purpose of this study was to reduce inappropriate revisits to the ED with a new method which was developed by analyzing inappropriate revisits in 2002. Methods : This study was conducted in a tertiary hospital consisting of 1,278 beds. The most common cause of inappropriate revisits was the medical team's lack of explanation about a disease. Thus we decided that the effective method was to offer full explanations to patients to understand the clinical pathway of a disease. We made four types of stickers to explain most common 4 diseases in 2003. An emergency physician completed 'discharge explanation report' and explained it to patients in 2004. Results : In 2002 inappropriate revisited patients were 164, patients with four diseases were 79. During the same period of 2003, inappropriate revisited patients were 56 (-65.9%), four disease patients were 6 (-92.4%) and in 2004 inappropriate revisited patients were 52, four disease patients were 19. Causes of revisits were lack of explanation about a disease in 35 patients (44.3%) in 2003, and 5 patients (83.3%) in 2003, and 16 patients (84.2%). Conclusions : Application of 'explanation stickers' at discharge reduced inappropriate revisits from 34.5% in 2002 to 15.9% in 2003. Application of 'Discharge explanation report' by emergency physician reduced inappropriate revisits from 15.9% in 2003 to 13.5% in 2004. Reduction of inappropriate revisits elevated the quality of medical treatment, and decreased patients' dissatisfaction in ED.

응급실에서 시행된 기관내 삽관의 현황

김병철,강보승,송형곤,이정훈,송근정,정연권 대한응급의학회 1999 대한응급의학회지 Vol.10 No.4

Background : The purpose of this study was to analyze the endotracheal intubation cases performed in the emergency department. Methods : We investigated retrospectively 326 cases of endotracheal intubation performed in the emergency department of a tertiary care center form April 1, 1998 to March 31, 1999. We focused on operators, medications used, its success rate and immediate complications, and the relationship between its success rate and medications. Results : Of 326 consecutive intubations, 193 patients(59.2%) were done by emergency medicine residents or attending physician. While 320 patients(98.2%) were successfully intubated, 6 patients could not be intubated and 2 patients underwent tracheostomy. Of 50 cases of intubations(15.3%) attempted with paralyzing agents, 48 cases were done with succinylcholine and 46 cases underwent by emergency physicians. Intubations with neuromuscular paralysis resulted in high success rates at the first attempt. Of 55 immediate adverse events were encountered in 47 patients(desaturation=17, bronchial intubation=15, hypotension=8, bradycardia=4, cardiac arrest=2, others=5). Conclusion : At this institution, paralyzing agents were used infrequently, but almost all of them were used by emergency physicians.

파라콰트 중독에서의 항산화치료

권운용,조유환,송형곤,김명천,이중의,서길준,윤여규 대한응급의학회 2001 대한응급의학회지 Vol.12 No.4

Background: Paraquat causes severe tissue toxicity when ingested, but has no effective treatment modality. We have shown that high dose vitamin C has effective antioxidant activities against the paraquat intoxication in a previous animal experiment. This study was designed to evaluate the effect of antioxidant therapy with high dose vitamin C and vitamin E in human cases of paraquat intoxication. Methods: From August 1999 to August 2001, 19 paraquat intoxication patients who visited the emergency department of the Seoul National University Hospital and the Kyounghee University Hospital were enrolled to this study. They were devided into two groups, a control group(9 patients) and a study group(10 patients). The control group received only conservative managements including gastro-intestinal decontaminati-on. The study group received conservative managements plus the antioxidant therapy which was composed of vitamin C 24 gm/day intravenously and 20 gm/day orally, and vitamin E 1.6 gm/day orally. Results: In the study group, 5 of 10 patients(50%) survived, but all patients of the control group died(p=0.003). There were no significant differences in age, sex, and usage of gastric lavage and activated charcoal between the two groups. Difference in ingested amount of paraquat between the two groups could not be analyzed due to the inexact and subjective measuring methods based on patients' histories. Conclusion: Antioxidant therapy with high dose vitamin C and vitamin E is effective in vival rate in paraquat intoxicated patients.

119구급대를 통한 서울지역 외상환자 진료체계에 대한 통계분석

서길준,이승한,조익준,권운용,송형곤,이중의,윤여규 대한응급의학회 2001 대한응급의학회지 Vol.12 No.2

Backgroud: Despite continous efforts to improve the prehospital trauma care system in Korea, the preventable death rate has been reported to be high. The purpose of this study was to evaluate the prehospital trauma care system in Seoul by analyzing 119 rescue databases. Methods: The 119 rescue data bases of 22,275 trauma patients, who were transported to the secondary and tertiary hospital in Seoul by Seoul 119 rescue services from January 1, 2000 to December 31, 2000, were analyzed. Results: The response time(mean 3.7 min.) showed no time, weekly, and regional variations. However, the transport time from field to hospital showed was high in the morning rush hour(7:00 to 10:00 am), and was gradually decreased and the lowest between 10:00 pm and 7:00 am. There was also a regional variation in the transport time, which was short in the central area and long in the peripheral area of Seoul. Prehospital cares were given to the 10,999 trauma patients(49.4%). Of the 464 unresponsive patients(2%), only 236 patients were identified in transported hospitals. The outcomes of these unresponsive patients were DOA(54%), survival(19%), death in ER(14%), transfer to other hospitals(8%), and death after admission(5%) in order. Conclusion: We suggest that this study may be helpful to the establishment and improvement of the prehospital trauma care system as well as the determination of the adequate numbers and locations of trauma center in Seoul.

Simultaneous synthesis and consolidation of nano-structured WSi2-NbSi2 composite by pulsed current activated heating and its mechanical properties

Hyoung-Gon Jo 한양대학교 세라믹연구소 2014 Journal of Ceramic Processing Research Vol.15 No.6

Nanopowders of W, Nb, and Si were fabricated by high-energy ball milling. A dense nanostructured WSi2-NbSi2 composite was simultaneously synthesized and sintered by the pulsed current activated heating method within four minutes using mechanically activated powders of W, Nb, and Si. A high-density WSi2-NbSi2 composite was produced under simultaneous application of an 80-MPa pressure and a pulsed current. The sintering behavior, mechanical properties, and microstructure of the composite were investigated.