Fe-Ni-Co 저열팽창성 합금의 고온 변형 특성 및 열간가공에 따른 열팽창 거동 연구

이기안,박종혁,조봉현,남궁정,김문철 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.9

The high temperature deformation behavior and the effect of hot compression on the thermal expansion behavior of Fe-29Ni-17Co low thermal expansion Kovar alloy were investigated in the compressive temperature range of 900~1300℃ at the strain rate range of 25~0.01 sec.^(-1). The temperature (T) and strain rate (ε˙) dependence of the flow stress (σ_(0.7)) could be well described by hyperbolic sine law as ε˙= A [sinh(0.0084 σ)^(5.2018)] exp(-330.41/RT). Surface hot cracking and significant voids around grain boundary could be found at low temperature below 1000℃ and low strain rate (0.01 sec.^(-1)). Thermal expansion coefficient α_(30~400) generally increased with increasing compressive temperature. Moreover, α_(30~400) remarkably increased as strain rate decreased at high temperature above 1100℃. However the thermal expansion coefficient α_(30~400) of low compressive temperatures (900℃ and 1000℃) anomalously increased especially at high strain rates. Experimental results indicated that not only α phase appearance but also grain size had definite influence on the thermal expansion behavior with hot deformation. The correlation between microstructure and thermal expansion behavior of Kovar alloy were also discussed.

저열팽창성 Fe-29Ni-17Co 코바 합금의 고온균열 발생과 고온연성에 미치는 S 및 Mn의 영향

이기안,박종혁,조봉현,남궁정,김문철 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.12

The effect of S & Mn on the hot ductility of Fe-29Ni-17Co Kovar alloy and the mechanism of high temperature cracking occurrence were investigated. It has been found that the brittle intergranular fracture at high temperature cracking is closely associated with the sulfide along grain boundary. Experimental results showed, especially when the S content was high and the Mn content was free, that small cavities could be nucleated easily on FeS particles along grain boundary and propagated fast at high temperature. The hot ductility of Kovar alloy was drastically increased with the addition of Mn and it was also increased with decreasing S content. SEM and FE-SEM analyses showed that the Mn addition in this alloy could cause ductile intergranular fracture appearance below 1150℃ by the precipitation of MnS. It was proposed from the results that the addition of Mn and optimum S content (below 30 ppm) in Kovar alloy was necessary in order to reduce the hot cracking susceptibility.

말초신경손상에 의한 척수감각신경 세포의 감작

강석한,김찬,엄민숙,김진혁,김기순 한양대학교 의과대학 1997 한양의대 학술지 Vol.17 No.1

Peripheral nerve injuries have been known to result in a chronic neuropathic pain characterized by symptoms of spontaneous burning pain, hyperalgesia, and allodynia. Recently it has been reported that the flexor reflex was greatly enhanced immediately after peripheral nerve section in the experimental animals. The persent study was underaken to investigte acute effects of the peripheral nerve injury on the sensitization of dorsal hom cells. After the sciatic nerve section, neither significant change was observed in the wind-up of WDR cells, nor wind-up was produced in the WDR cell that had not shown wind-up before the afferent nerve section. The A-fiber responses of WDR cells were not altered after section of the sciatic nerve. However, the C-fiber responses and after-discharge of the dorsal horn cell to imput signals started to increase in 2 hours after the nerve section. In 70% of experimental animals, the nerve section-induced increments in the WDR cell activities were abolished after topical application of 2% lidocaine to the proximal end of cut sciatic nerve. After pretreatemnt of the experimental animals with a NMDA receptor blocker, MK-801, the C-fiber response and after-discharge of the dorsal horn cell well not changed by the sciatic nerve section. These findings suggest that peripheral injury induces the sensitization of dorsal horn cells of the spinal cord and that signals from the proximal stump is essential for maintenance of the sensitization, which was mediated by NMDA receptors.

실험적 국소뇌허혈이 대뇌피질 칼슘결합단백-양성 세포에 미치는 영향

강사준,김재휴,조진호,이제혁,우정현,이기영,배춘상 대한신경외과학회 1992 Journal of Korean neurosurgical society Vol.21 No.6

To understand the changes in expression of calcium binding proteins(CaBP) during the experimental focal ischemia, expression of two kinds of CaBP, parvalbumin(PV) and calbindin D-28K(Calbindin), immunocytochemically, and activities of cytochrome oxidase(CO) and acetylcholinesterase(AChE), histochemically, in focal ischemic brain of the rat were investigated. Two groups of focal ischemic infarction were produced in Sprague Dawley rats(200∼350㎎): Group Ⅰ. Clip compression of left middle cerebral artery(MCA) for 5∼10 mins and release; Group Ⅱ, Electric coagulation of left MCA for 2∼24 hrs. In the group Ⅰ, CO activity and PV-and Calbindin-immunoreactivity(IR) were decreased in the left MCA territory, and decreased in number of PV-and Calbindin-IR neurons and degree of IR, but AChE activity was nearly same as that of control cortex. In the group Ⅱ, decrease of CO and AChE activities, and marked increase of PV-and Calbindin IRs were noted on neuropil in the layers Ⅰ through Ⅵ of ischemic region. Characteristically pyramidal cells, which did not express the both CaBPs in the control cortex, of layer Ⅴ of ischemic cortex showed PV-and Calbindin IRs in the cell body and apical dendrite. These findings suggest that 1) PV-and Calbindin-IR neurons, mainly non-pyramidial cells, are more vulnerable than pyramidal cell to ischemic injury. 2) CaBP may have some roles in hypoxic neuronal injury, and 3) PV and Calbindin-immunocytochemistry can be used as useful technique in evaluation of experimental ischemia.

사람 뇌척수액중 Transthyretin의 항산화작용

양성렬,최기오,박종근,류문희,홍석노,김수한,안봉환,이제혁,이민화 대한신경외과학회 1994 Journal of Korean neurosurgical society Vol.23 No.4

Protective effects of human cerebrospinal fluid antioxidants against enzyme inactivation caused by metal-catalyzed oxidation systems were investigated. When purified glutamine synthetase(GS) was incubated with human cerebrospinal fluid(CSF), the enzyme was progressively inactivated. Catalase and EDTA could inhibit the enzyme inactivation by 50-80%. Small-molecular(Mr< -10,000) fraction of CSF inactivated the exogenous GS, but large-molecular(Mr> -10,000) fraction did not. The GS inactivation by the small-molecular fraction was also markedly inhibited by catalase and EDTA. These results suggested that metal-catalyzed oxidation is involved in the GS inactivation by the small-molecular fraction of CSF. Dithiothreitol(DTT) was shown to inhibit almost completely the oxidative inactivation of GS by CSF. However, DTT inhibited only partially the oxidative inactivation of GS caused by small-molecular fraction of CSF. When large-molecular fraction of CSF was separated by anion-exchange HPLC chromatogrpahy, there was a peak of antioxidant activity inhibiting the small-molecular fraction-induced GS inactivation in the presence of DTT. The antioxidant activity was neutralized by monoclonal antibodies to transthyretin. Purified transthyretin was found to efficiently inhibit ascorbate/Cu^(2+)-induced GS inactivation in the presence of DTT. Uric acid and glucose did not show any protective effect on the GS inactivation in the same condition. The above results suggest that metal-catalyzed oxidation occurs normally in human CSF, and that transthyretin may play an important role as a CSF antioxidant in protecting proteins from metal-catalyzed oxidation.

관동맥 재개통 후 QTc간격분산의 감소 : 정량적으로 측정한 심근 허혈의 호전 정도와의 연관성 Relationships with the Quantitative Degree of Improvement in Myocardial Ischemia

박상선,최기준,남기병,이철환,홍멸기,박성욱,박승정,신중우,문대혁,김유호 대한순환기학회 2000 Korean Circulation Journal Vol.30 No.8

급성 cadmium chloride 중독이 백서 심장 전도계 및 수축기능에 미치는 영향

김경수,이재웅,김순길,김정현,임헌길,이방헌,이정균,김진혁,김기순 한양대학교 의과대학 1995 한양의대 학술지 Vol.15 No.2

Cadmium is widely used in electroplating, plastic engineering and for manufacturing color pigment and nickel-cadmium batteries. As the chances of exposure to cadmium increase, cadmium poisoning is becoming one of the major problems in heavy metal toxicity not only in industrial workers but also in general populations. Not infrequently coronary artery disease, hypertension and cerebrovascular accidents are related to a chronic exposure to cadmium. Cadmium is known to decrease cardiac contractility and also to cause dilated cardiomyopathy as well as abnormalities in the cardiac conduction system. In most of previous studies on acute toxic effects of cadmium on the heart, Langendorff's heart preparations were routinely perfused with solutions containing varying amount of cadmium. Though employment of Langendorff's heart prepartion was ideal method for exploring the effect of cadmium per se, the route of cadmium administration was rather not physiological i.e., effect of cadmium toxicity in vivo could not be assessed. In the present study cadmium was administrated into the peritoneum of rats and animals were sacrificed in 1 hour to 5 days after cadmium administration. To observe the effects of acute cadmium poisonging on the cardiac conduction system and myocardial systolic function, Langendorff's heart preparations were made and the RR interval, AH interval, HV interval, systolic acortic pressure and maximal dP/ dT of aortic pressure were measured in these heart preparations. 1) The RR intervals were increased significantly only in 3 hours after cadmium administration. A significant increase in the RR intervals was observed in 3 hours after cadmium administration. 2) The AH intervals started to increase significantly in 1 hour, peaked in 3 hours and returned to normal in 6 hours after cadmium administration. 3) The HV intervals started to increase significantly in 3 hours, peaked in 6 hours and returned to normal in 24 hours after cadmium administration. 4) The aortic systolic pressures and miximal dP/ dT started to decrease in 1 hour, showed persistent marked decrease until 2 days and returned to normal in 5 days after cadimum administration. The present results indicate that the recovery time from acute cadmium poisoning is different between the conduction system and the moyocardium possibly due to differencesn action sites of cadmium and/or in distribution of calcium channels in the cardiac tissues.

Effect of acupuncture on 6-hydroxydopamine-induced nigrostratal dopaminergic neuronal cell death in rats

Kim, Yeung-Kee,Lim, Hyung-Ho,Song, Yun-Kyung,Lee, Hee-Hyuk,Lim, Sabina,Han, Seung-Moo,Kim, Chang-Ju EAST-WEST MEDICAL RESEARCH INSTITUTE KYUNG HEE UNI 2005 東西醫學硏究所 論文集 Vol.2005 No.-

In this study, we investigated the effect of acupuncture at the Zusanli acupoint (ST36) on the nigrostriatal dopaminergic neuronal cell death in the rats with Parkinson's disease. Two weeks after unilateral injection of 6-hydroxydopamine(6-OHDA) into the striatum, an apomorphine induced rotational behavior test showed significant rotational asymmetry in the rats with Parkinson's disease. Immunostaining for tyrosine hydroxylase demonstrated a dopaminergic neuronal loss in the substantia nigra and dopaminergic fiber loss in the striatum. Acupuncture at the ST36 for 14 days significantly inhibited rotational asymmetry in the rats with Parkinson's disease, and also protected against 6-OHDA-induced nigrostriatal dopaminergic neuronal loss. These effects of acupuncture were not observed for the non-acupoint (hip) acupuncture. The present study shows that acupuncture at the ST36 acupoint can be used as a useful strategy for the treatment of Parkinson's disease.

가토 심방근 및 동방결절세포의 전기적 특성에 미치는 Porcine Bile의 효과

김기순,신홍기,김진혁,김윤호 한양대학교 의과대학 1987 한양의대 학술지 Vol.7 No.2

The porcine bile is characterized by high proportion of dihydroxy bile salts with respect to trihydroxy bile salts, and it s predominant bile acid is known to be hyodeoxycholate. Study on the elctrophysiological effect of hyodeoxycholate has been limited by the fact that this bile salt is insoluble in water. In the present study effects of porcine bile on the cellular potentials of the rabbit atrial muscle and the sinus node cells were examined. The maximum diastolic potential (MDP) and overshoot potential (OS) of the atrial muscle fiber were significantly decreased b porcine bile. When the atrial muscle was superfused with 0.25% porcine bile, action potential decreased between 15 and 20 minutes after start of superfusion, while it decreased form 5 to 30 minutes following superfusion with 0.5% bile solution. Although porcine bile did not alter action potential duration (APD) of the atrial muscle fiber, it markedly decreased the rate of self-beating. And also action potential of the sinus node cells was attenuated by porcine bile as the result of decrease in MDP and OS. On the other hand, porcine bile decreased V? of the sinus node cells significantly. APD of the sinoatrial node cell was not affected by porcine bile, but arrhythmias were often observed following superfusion of the sinus node cells with porcine bile solution(0.5%).

Amiodarone에 의한 폐독성 1예

김인기,정병오,이혁표,김주인,염호기,최수전,김두일,김동수,양영일,최석진 인제대학교 1999 仁濟醫學 Vol.20 No.1

저자들은 심실성 빈맥으로 amiodarone 일일 400mg을 약 1년 6개월 정도 사용해 오던 환자에서, amiodarone에 의해 유발된 간질성 폐렴 1예를 경험하였기에 문헌고찰과 함께 보고하는 바이다. Amiodarone is a very effective antiarrhythmic agent frequently employed in patient with life-threatening supraventircular tachycardia and ventricular tarchycardia. But amiodarone is associated with a number of side effect, which include liver dysfunction, hyper- and hypothyroidism, bluish discoloration of skin, bone marrow suppression, coagulopathies, peripheral neuropathy, and others. The most serious adverse effect is a pulmonary toxicity which occurs in average 4% to 6% of those patients on the drug and maybe fatal. Two possible mechanisms of amiodarone pulmonary toxicity have been suggested, a direct toxic effect or an immune-mediated response. We report a case of patient with amiodarone pulmonary toxicity who has taking 400mg of amiodarone per day for reccurent ventircular tachycardia.