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유춘원,권영환,김진석 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
In this study, polyurethane (PU) composites with 5 different classes of hollow glass microspheres (HGMs) were prepared. The 5 HGMs used in composites had similar mean diameter but different shell thickness, reflecting as a difference in their density. The effect of shell thickness of HGMs on thermal insulation, thermal stability, dimensional stability and mechanical properties was investigated. It was found that the incorporation of HGMs enhanced thermal and mechanical properties with increasing content of HGMs in PU composites. The result also appeared that thin walled HGM had greater capacity to increase thermal insulation performance. However, thick walled HGM had considerable benefit in improving thermal stability and mechanical properties. There was no obvious effect of shell thickness on dimensional stability.
Preparation and thermal insulation behavior of inorganic particle filled polyurethane composites
유춘원,권영환,김진석 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1
Silica aerogel and hollow glass microspheres are well known as inorganic thermal insulating particle due to their low thermal conductivity. Effects of this kind of particles on mechanical property, thermal stability and thermal insulating property in polyurethane (PU) films are investigated in this work. For this study, series of PU matrixes are prepared by prepolymer hydroxyl-terminated poly(propylene glycol) and poly(tetrahydrofuran) prepolymers reacted with isocyanate isophorone diisocyanate and poly[(phenyl isocyanate)-co-formaldehyde]. This work is focused on effect of inorganic particle on thermal insulation behavior of PU composites. In order to identify the ability of preventing thermal transfer, thermal conductivity (k) as an important heat insulating property of materials, is measured by a transient plane method, and analyzed by 5 theoretical models published in previous paper.
홍병철 ( Bing Zhe Hong ),유춘원 ( Chun Won Yoo ),김한규 ( Han Kyu Kim ) 전북대학교 의과학연구소 2004 全北醫大論文集 Vol.28 No.1
Hydrogen peroxide의 농도에 따른 심장기능 조절작용을 규명하고자, 심방에서 중요한 기능을 한다고 알려진 hKv1.5유전자를 HEK-293 cell 및 Ltk- cell에 발현시켜 유도된 K* 전류 및 사람 심방 세포의 K*전류에 미치는hydrogen peroxide의 영향을 관찰하여 다음과 같은 결과를 얻었다. 1. Hydrogen peroxide는 HEK-293 cell 및 Ltk- cell에서 Kv1.5 전류의 activation curve의 전압의존성을 과분극 쪽으로 약20 mV정도 이동시켜 전류를 증가시켰다. 또한, HEK-293 cell에서 Kv1.5/Kvβ1.3전류의 activation curve의 전압의존성올 이동시켰을 뿐 만 아니라 fast inactivation을 하였다. 2. Ltk- cell에서 0.01-0.3 mM의 hydrogen peroxide는 Kv1.5를 증가시켰고 1 mM이 상에서는 현저히 감소시켰다. 3. 사람 심방세포서 1 mM의 hydrogen peroxide는 steady state outward 전류를 5배 이상 증가시켰다. 이상의 실험성적은 hydrogen peroxide가 농도에 따라 hKv1.5전류를 조절할 수 있음을 밝혔는데, 특히 비교적 낮은 농도의 hydrogen peroxide는 이 전류를 증가시킴을 사람심방세 포에서 확인하였다. During myocardial ischemia and subsequent reperfusion, reactive oxygen species are an important mediator of cellular damage and rhythm disturbances. H2O2, a small, uncharged and relatively stable molecule that diffuses easily through tissue, has several adverse effects on the myocardium including induction of cardiac arrhythmias. Although several previous investigations have described electro-physiological effects of H2O2 in mammalian myocardium, the underlying ionic mechanisms of H2O2 effects remain unclear. In addition, voltage gated K* channels represent the most complex group of ion channel genes expressed in cardiovascular system. The human Kv1.5 channel (hKv1.5) represents the IKur repolarizing current in atrial myocytes. The hKv1.5 channel is functionally modulated by the Kvβ1.3 subunit, which converts it from a delayed rectifier to a channel with rapid inactivation and enhanced voltage sensitivity. In present study, we examined the effects of H2O2 following coexpression of hKv1.5 with the Kvβ1.3 subunit in LtK-cells and HEK-293 cells. H2O2 (1 mM) reversibly increased the K* currents in the cells transected with hKv1.5 and/or Kvβ1.3 or Kvβ2.1 subunits. Additionally, H2O2 slowed deactivation and fast inactivation in the cells cotransfected with hKv1.5 and/or Kvβ1.3 or Kvβ2.1, and made the hyperpolizing shift of activation curve by about 20 mV. However, higher concentration of H2O2 (higher than 1 mM) decreased the hKv1.5/Kvβ2.1 current. Catalase (1000 u/ml) itself accelerated the inactivation process of hKv1.5 current and decreased the steady state current. In isolated human atrial myocytes, H2O2 (1 mM) reversibly increased the outward K* currents by about five times. These results reported that H2O2 has a dual effect on hKv1.5 current, thereby being able to explain the potential roles of H2O2 during myocardial reperfusion injury.
송희선,이상귀,송정자,고성훈,유춘원 대한마취과학회 1996 Korean Journal of Anesthesiology Vol.31 No.4
Pulmonary embolism is a common and lethal, which accounts for substantial morbidity and mortality. Clinical manifestations of pulmonary embolism are nonspecific during general anesthesia. A 60 years old female received elective operation for left femur fracture under general anesthesia. At the end of operation, she suddenly became hypotensive and developed cyanosis. Immediate cardiopulmonary resuscitation(CPR) was performed without definitive diagnosis. Pulmonary embolism was suspected by clinical signs and echocardiography. So, patient was transferred to intensive care unit and with intensive care and aggressive treatment, patient's vital signs and ventilatory status were progressively improved. However, the endotracheal tube was accidentally extubated by the patient at the second postopetative day, and then cardiac arrest was developed and the patient expired. The primary goal of therapy for pulmonary embolization is to prevent reembolization. In the pulmonary thromboembolization, early diagnosis and intensive care improve outcome.