• Journal of Chest Surgery
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• 제25권7호
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• pp.693-701
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• 1992

Extracorporeal cardiopulmonary bypass[CPB] has been associated with a wide variety of hematologic derangements, including a transient deformation and hemolysis of red blood cells[RBCs], which is supposed to be due to mechanical trauma and/or metabolic alterations. Since membrane integrity is, in part, maintained by energy requiring process, inadequate function of erythrocyte glycolytic pathway, which is inevitalble during CPB, may cause depletion of high energy phosphate pool and result in hemolysis. The authors performed an investigation to assess whether administration of Fructose-l, 6-diphsphate [FDP], which has been known to enhance intracellular glycolytic activities, could counteract erythrocyte hemolytic events caused by CPB. Sixty pateints with cyanotic congenital heart diseases, who underwent open heart surgery under CPB longer than 60 minutes, were randomly divided into two groups depending on whether use of FDP[Group FDP] or not[Group Control]. The age, sex, CPB time, preoperative hemoglobin level, disease entities were all similar[Table 1], and membrane type oxygenators were used in all patients. In Group, FDP, a dose of 250mg/kg body weight of FDP was administered by intravenous dripping every 12 hours from the morning of the operation to postoperative 48 hours, To demonstrate the degree and pattern of hemolysis of erythrocyte, reticulocyte count, indirect /direct bilirubin, haptoglobin, plasma hemoglobin, lactate dehydrogenase were measured every 12 hours from the time of cessation of CPB to 48 hours and RBC morphologic study, osmotic fragility test were done every 24 hours. All parameters revealed less hemolytic in group FDP [Fig. 1~5], though the differences between two groups were not significant, except plasma hemoglobin, lactate dehydrogenase changes. A pattern of sequential changes of plasma hemoglobin, lactate deh-ydrogenase showed the highest level at the time of CPB stop and abrupt decrease in following 24 hours in both groups, and statistically significant differences were demonstrated in group FDP at least for the first 12 hours postoperatively[p<0.05]. The authors conclude that they can expect the benificial effect of FDP on the maintenance of membrane stability of RBC probably by energy enhancement during the shock status of CPB, but FDP could not completely prevent the damaging effect on RBC by cardiopulmonary bypass

• 한국전자통신학회논문지
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• 제18권5호
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• pp.747-754
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• 2023

다양한 환경에 배치된 센서 노드(Sensor Node)로부터 획득한 정보들을 무선으로 수집하여 감시 및 제어 등의 용도로 활용되고 있는 무선 센서 네트워크에서 에너지 효율적인 라우팅 프로토콜은 중요한 과제이다. 이에 대한 다양한 라우팅 기법이 연구가 되었으나, 특정 상황과 조건이 있는 WSN 환경에 대한 고려 또한 필요하다. 특히, 지형적 특성이나 특정 장애물로 인해 센서 노드가 배치되어 있지 않은 장소(Hole)는 대다수의 WSN 환경에서 존재할 수 있고 이는 비효율적인 라우팅 또는 라우팅 실패가 있을 수 있다. 이 경우 GPS 기능을 활용한 지리적 라우팅 기반의 홀 우회 라우팅 방식이 가장 효율적인 경로를 형성하겠지만 GPS 기능을 가지고 있는 센서는 비용이 많이 들고 에너지 소모가 크다는 단점이 있다. 따라서 최소한의 센서 기능을 통해 홀이 있는 WSN 환경에서 홀의 경계 노드를 찾아 경계선 형성을 통한 홀 우회 라우팅을 제안하고자 한다.

• 한국초전도ㆍ저온공학회논문지
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• 제22권1호
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• pp.7-11
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• 2020

As demand for electricity in urban areas increases, it is necessary to improve electric power stability by interconnecting neighboring substations and high temperature superconductor (HTS) power cables are considered as a promising option due to its large power capacity. However, the interconnection of substations reduces grid impedance and expected fault current is over 45 kA, which exceeds the capacity of a circuit breaker in Korean grid. To reduce the fault current below 45 kA, a HTS power cable having a fault current limiting (FCL) function is considered by as a feasible solution for the interconnection of substations. In this study, a FCL HTS power cable of 600 MVA/154 kV, transmission level class, is considered to reduce the fault current from 63 kA to less than 45 kA by generating an impedance over 1 Ωwhen the fault current is induced. For the thermal design of FCL HTS power cable, a parametric study is conducted to meet a required temperature limit and impedance by modifying the cable core from usual HTS power cables which are designed to bypass the fault current through cable former. The analysis results give a minimum cable length and an area of stainless steel former to suppress the temperature of cable below a design limit.

• Journal of Chest Surgery
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• 제14권3호
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• pp.187-194
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• 1981

Cardiac surgery is generally followed by a period of routine ventilator support. When the patient seems hemodynamically stable and relatively alert following surgery, respiratory adequacy is tested by the weaning trial. In this study, physiological and clinical prediction of postoperative respiratory adequacy, including values of pulmonary function tests, were examined in an attempt to identity those few variables which predicted the outcome of the ventilator weaning trial following surgery. Our series comprised 27 patients who underwent elective open intracardiac operations at the Department of Thoracic and Cardiovascular Surgery, School of Medicine, Kyungpook National University, from October 1979 to July, 1980. The pulmonary function tests performed on all patients included the following; forced vital capacity [FVC], forced expiratory volume [FEV1.0], forced expiratory flow [FEF 25--75~], residual volume [RV], and functional residual capacity [FRC], measured with a helium dilution technique. Of our 27 patients, 8 were successfully weaned within 20 hours of operation. All patients with cyanotic heart diseases or acquired heart diseases were unsuccessfully weaned. The bypass time in the successful weaning group was shorter in the mean value [82.8 minutes]than in the unsuccessful weaning group [120.5 minutes]. There was a relatively significant difference in the mean values for the two groups in arterial pressure, bleeding amounts and FiO2 among the postoperative monitoring variables, and in forced vital capacity [FVC]. The postoperative clinical assessments appeared vague but corresponded reasonably well to appraisal of success in weaning, especially in variables of cough and self-respiration efforts.

• Journal of Chest Surgery
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• 제47권3호
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• pp.240-248
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• 2014

Background: Open heart surgery using cardiopulmonary bypass (CPB) is considered one of the most frequent surgical procedures in which acute kidney injury (AKI) is a frequent and serious complication. The aim of the present study was to evaluate the efficiency of neutrophil gelatinase-associated lipocalin (NGAL) as an early AKI biomarker after CPB in cardiac surgery (CS). Methods: Thirty-seven adult patients undergoing CS with CPB were included in this retrospective study. They had normal preoperative renal function, as assessed by the creatinine (Cr) level, NGAL level, and estimated glomerular filtration rate. Serial evaluation of serum NGAL and Cr levels was performed before, immediately after, and 24 hours after the operation. Patients were divided into two groups: those who showed normal immediate postoperative serum NGAL levels (group A, n=30) and those who showed elevated immediate postoperative serum NGAL levels (group B, n=7). Statistical analysis was performed using Statistical Package for the Social Sciences version 18. Results: Of the 37 patients, 6 (6/37, 16.2%) were diagnosed with AKI. One patient belonged to group A (1/30, 3.3%), and 5 patients belonged to group B (5/7, 71.4%). Two patients in group B (2/7, 28.5%) required further renal replacement therapy. Death occurred in only 1 patient (1/37, 2.7%), who belonged to group B. Conclusion: The results of this study suggest that postoperative plasma NGAL levels can be used as an early biomarker for the detection of AKI following CS using CPB. Further studies with a larger sample size are needed to confirm our results.

• Journal of Korean Society for Atmospheric Environment
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• 제11권E호
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• pp.45-54
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• 1995

Indoor air quality models are useful to predict indoor air pollutant concentrations as a function of several indoor factors. Indoor air quality model was developed to evaluate the pollutant removal efficiency of variable-air-volume/bypass filtration system (VAV/BPFS) compared with the conventional variable-air-volume (VAV) system. This model provides relative pollutant removal effectiveness of VAV/BPFS by concentration ratio between the conventional VAV system and VAV/BPFS. The predictions agree closely, from 5 to 10 percent, with the measured values for each energy load. As a results, we recommend the VAV/BPFS is a promising alternative to conventional VAV system because it is capable of reducing indoor air pollutant concentration and maintaining good indoor air quality.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.182-188
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• 2017

An arc eliminator allows a surge current bypass rapidly into the earth to facilitate the circuit breaking process and increase the stability of the load circuit. Thomson coil actuator (TCA) is a type of actuator that can function as an arc eliminator. The TCA has a simple structure and significantly rapid speed compared to the other types of actuators. In this paper, significant variables, which have a dominant effect on the performance of the TCA, are investigated in detail. Using these variables and an optimization algorithm, an optimal design strategy for the TCA is proposed in this research. The efficacy of the proposed optimal design strategy and the feasibility of the application of the designed TCA for a high power circuit breaker as the arc eliminators are validated through the experiment.

• Journal of Chest Surgery
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• 제28권3호
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• pp.247-252
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• 1995

The isolated coronary ostial stenosis is rare and a critical lesion which requires urgent surgical intervention. Recently direct angioplasty is assumed as a preferable approach to conventional bypass grafting. From Mar. 1990 to Aug. 1993, six patients underwent direct angioplasty in Sejong Heart Institute. The mean age of 6 patients was 48 years [range 37 to 63 and they consisted with 5 females and one male. All had severe angina [class III or IV of short duration [mean 5.3 months and a low incidence of risk factors. Despite the crucial location of the lesion, most patients had well preserved left ventricular function and normal wall motion. We performed direct angioplasty with autologous pericardium via anterior approach except one patient who underwent direct angioplasty and CABG. One patient died 4 hours after angioplasty probably due to acute coronary dissection. The survived 5 patients maintain normal life without symptoms during 26.2 months follow up [range 5 to 47 months .Our preliminary results suggest that angioplasty of isolated coronary ostial stenosis in highly selected patient can be carried out with good results and relatively low operative risks.

• Journal of Korean Neurosurgical Society
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• 제55권2호
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• pp.99-102
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• 2014

A previously healthy 52-year-old man presented to the emergency room with acute onset left hemiparesis and dysarthria. Brain computed tomography and magnetic resonance examinations revealed acute cerebral infarction in the right middle cerebral artery territory and a sphenoid ridge meningioma encasing the right carotid artery terminus. Cerebral angiography demonstrated complete occlusion of the right proximal M1 portion. A computed tomography perfusion study showed a wide area of perfusion-diffusion mismatch. Over the ensuing 48 hours, left sided weakness deteriorated despite medical treatment. Emergency extracranial-intracranial bypass was performed using a double-barrel technique, leaving the tumor as it was, and subsequently his neurological function was improved dramatically. We present a rare case of sphenoid ridge meningioma causing acute cerebral infarction as a result of middle cerebral artery compression.

• The Korean Journal of Pain
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• 제19권2호
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• pp.271-274
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• 2006

Unstable angina is a critical phase of coronary heart disease, with widely variable symptoms and prognoses. Recently, despite the advances in surgical revascularization, catheter-based revascularization and medical treatment, an increasing number of patients with angina pectoris are refractory to medical therapy and; therefore, can not be considered as candidates for coronary artery bypass grafting or interventional angioplasty. These patients are often treated with narcotics for pain relief, and forced to severely reduce their levels of activity and productivity. It has become clear that alleviating the pain caused by myocardial ischemia may be possible by altering the sympathetic afferent nerve fibers. Sympathetic blockade can be produced using high thoracic epidural analgesia. Herein, the case of a patient with intractable angina and poor ventricular function, who received high thoracic epidural analgesia to relieve ischemic chest pain, is reported.