• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.9
• /
• pp.1706-1713
• /
• 2009

In this paper, a parallel operation algorithm for high power PEMFC generation systems is proposed. According to increasing the capacity of fuel cell systems with several fuel cell stacks, the different dynamic characteristics of each fuel cell stack effect on imbalance of load sharing and current distribution, so that a robust parallel operation algorithm is desired. Therefore, a power-sharing technique is developed and explained in order to design an optimal distributed PEMFC generation system. In addition, an optimal controller design procedure for the proposed parallel operation algorithm is introduced, along with informative simulations and experimental results.

• Childhood Kidney Diseases
• /
• v.15 no.1
• /
• pp.58-65
• /
• 2011

Purpose: Some hormonal and electrolyte abnormalities have been reported in pediatric patients with urinary tract infection (UTI). This study aimed to investigate the relationships between the imbalance of electrolytes and the severity of infection and associated urologic anomalies in children with febrile UTI. Methods: We retrospectively reviewed 267 patients with febrile UTI who were admitted to Korea University Guro Hospital during the period from January, 2007 until February, 2010. According to the presence of hyponatremia or hyperkalemia, clinical parameters and associated renal anomalies, such as hydronephrosis, cortical defects and vesicoureteral reflux, were compared. Results: 42.7% of all patients had decreased concentration of serum sodium. In patients with decreased concentration of serum sodium, cortical defects were significantly increased compared to normal patients (40.4% vs. 14.4%, P <0.05). White blood cell (WBC) counts ($15,721{\pm}6,553/uL$ vs. $12,885{\pm}5,367/uL$, P <0.05), C-reactive protein (CRP) ($61.8{\pm}56.1$ mg/L, vs. $29.9{\pm}39.8$ mg/L, P <0.05), and erythrocyte sedimentation rate (ESR) ($43.9{\pm}34.3$ mm/hr vs. $27.4{\pm}26.8$ mm/hr, P <0.05) in peripheral blood showed significant increases in the group with decreased concentration of serum sodium. Duration of fever, presence of gastrointestinal symptom, the incidence of hydronephrosis and vesicoureteral reflux did not differ between the two groups. None of the patients had significant hyperkalemia. Conclusion : We suggest that decreased concentration of serum sodium in febrile UTI might be a helpful marker for leukocytosis and increased CRP and ESR in peripheral blood, and acute pyelonephritis.

• Journal of Korean Biological Nursing Science
• /
• v.15 no.3
• /
• pp.139-146
• /
• 2013

Purpose: The purpose of this study was to identify knowledge and the Need of pathophysiology, perceived connectivity between knowledge of pathophysiology and clinical practice, and confidence and satisfaction with clinical performance by applying the knowledge to clinical practice, and to analyze the correlation between the knowledge, perceived connectivity, and confidence and satisfaction of clinical nurses. Methods: Subjects consisted of 149 clinical nurses who work at 7 general hospitals and 6 university hospitals located in Seoul, Incheon, and Gyeonggi province in Korea. Those who learned pathophysiology during their undergraduate program were recruited by using a convenient sampling. The data were collected between April 23 and May 24 in 2012. Participants responded to self-administered questionnaires about knowledge and the need of pathophysiology, and the perceived connectivity between knowledge and clinical practice, and confidence and satisfaction with clinical performance by applying knowledge to clinical practice. Results: Mean scores of knowledge and the need of pathophysiology were $2.88{\pm}0.34$ and $2.33{\pm}0.39$ each. Scores of knowledge and the need of 3 units such as fluid and electrolyte imbalance, acid-base imbalance, and alterations in the respiratory system were high among 23 units while that of adolescent disorders was the lowest. The mean score of perceived connectivity between knowledge and clinical practice was $7.32{\pm}1.57$, and those of confidence and satisfaction with clinical performance by applying the knowledge to clinical practice were $7.66{\pm}1.66$ and $7.42{\pm}1.67$ respectively. Knowledge of pathophysiology was positively correlated with the perceived connectivity between knowledge and clinical practice, and confidence, and satisfaction with clinical performance. Conclusion: The results indicate that knowledge and the need of pathophysiology in clinical nurses is above average, and that knowledge of pathophysiology is important in promoting perceived connectivity with clinical practice and increasing confidence and satisfaction with clinical performance by applying knowledge to clinical practice.

• Journal of Korean Biological Nursing Science
• /
• v.9 no.1
• /
• pp.85-102
• /
• 2007

Purpose: Knowledge on pathophysiology is important to understand diseases and patient conditions and also in providing advanced nursing care. This study was performed to investigate the present situation, knowledge, and educational need on pathophyiology of advanced practice nurses(APN). Method: Eighty-four APN, who is practicing in hospitals nationwide, were surveyed with structured questionnaires developed by researchers. The questionnaire were composed of 109 items with 4 point scales with the contents of general characteristics, educational experience on pathophyisology, educational need, and knowledge on major and subcategories of pathophysiology. Result: The 77.1% of APN had experience of taking pathophysiology lecture and the lecturer were mainly medical doctors(39.8%) and APN(32.4%). The 61.5% of APN answered that the knowledge on pathophysiology was helpful and 97.6% of APN thought pathphysiologic education is needed in clinical practice. Seven major categories of pathophysiology showed higher scores were water imbalance, heart diseases, hemodynamic disorders, arterial vessel disorders, electrolyte imbalance, diseases of the digestive system, and diseases of the respiratory systems. Educational needs on the major and subcategories of pathphysiology were different by the field of APN and also by the clinical experiences as APN. APN also responded that there is a necessity to change the present curricular more specific to each practice field and more focus on the clinical practice. Conclusion: It was confirmed that educational and clinical need on the pathophysiology is very high and there is urgent need to change current curricular more specific to the field of APN and also clinical practice. This survey will help to identify and clarify the areas of change and to improve the education for the APN.

• Clinical and Experimental Pediatrics
• /
• v.52 no.10
• /
• pp.1061-1068
• /
• 2009

The treatment of pediatric patients with chronic renal disease comprises management of nutritional imbalance, fluid, electrolyte, and acid-base disturbances, mineral bone disease, anemia, hypertension, and growth retardation. The treatment also includes administration of appropriate renal replacement therapy, if required. Adequate dietary intake of carbohydrates, fats, and proteins and caloric intake must be encouraged in such patients to ensure proper growth and development. In addition, fluid, electrolyte, and acid-base status must be regularly monitored and should be well maintained. Serum calcium, phosphorus, and parathyroid hormone levels must be maintained at their target range, which are determined on the basis of the glomerular filtration rate, to avoid the development of mineral bone disease. This can be achieved by using phosphorus binders and vitamin D analogues. An erythropoiesis-stimulating agent must be administered along with iron supplementation to maintain the hemoglobin level of the patients between 11-12 g/dL. Hypertension must be controlled with adequate water and sodium balance and appropriate antihypertensive agents. Administration of recombinant human growth hormone is recommended to improve the final adult heights.

• Journal of Veterinary Clinics
• /
• v.33 no.1
• /
• pp.34-38
• /
• 2016

A 13-year-old castrated male mixed breed dog and a 12-year-old castrated male mixed breed cat were referred to the hospital for the treatment of pulmonary edema and azotemia at the same time. To resolve the pulmonary edema and azotemia, intermittent hemodialysis (HD) was performed using ultrafiltration (UF), and the pulmonary edema, azotemia, other electrolyte and acid-base imbalances were improved. This case study demonstrated that when we encountered pulmonary edema patients with diuretic resistance, severe electrolyte imbalance, and impaired renal function complicated by decongestive therapy using diuretics, UF therapy can be considered a life-saving intervention.

• Journal of Veterinary Science
• /
• v.21 no.2
• /
• pp.17.1-17.11
• /
• 2020

Dehydration, electrolyte disturbance, and acid-base imbalance are the most significant consequences of diarrhea in calves. We aimed to determine blood gas, hematological, electrolyte, and biochemical values and investigate the relationship between the physical status and blood parameters in Korean native calves (KNCs) with diarrhea. One hundred eighty KNCs with diarrhea (age < 75 days) were investigated. Blood samples were collected from the external jugular vein and analyzed using a portable clinical blood gas analyzer. The measured parameters were statistically compared according to the status of physical activity, dehydration, or prognosis. The mean values of parameters in the Calves with diarrhea showed metabolic acidosis, hyponatremia, and azotemia. The mean values of potassium, chloride, hematocrit, and hemoglobin were in the upper limit of their reference ranges. More than 75% of the calves had metabolic acidosis caused by bicarbonate loss, and 63.6% had high blood urea nitrogen (BUN) values. Moreover, BUN showed the highest correlation with the physical activity status and dehydration. pH, base excess of the extracellular fluid (BE), anion gap, potassium, hematocrit, bicarbonate, and hemoglobin were closely correlated with physical deterioration and dehydration (p < 0.001). BUN, pH, BE, and anion gap were closely correlated with physical deterioration and dehydration. These correlations between clinical symptoms and blood gas parameters can be clinically relevant in predicting the status of parameters according to clinical symptoms.

• Membrane Journal
• /
• v.33 no.3
• /
• pp.127-136
• /
• 2023

In this study, the electrochemical performance of a 5-layer fuel cell stack using silica composite membranes as polymer electrolyte membranes was evaluated. It was observed that the flow rate of the fuel gases plays a crucial role in stack performance, particularly being mainly dependent on the flow rate of hydrogen. Increasing the flow rate of oxygen resulted in negligible changes in performance, whereas an increase in the flow rate of hydrogen demonstrated performance improvements. However, this led to an imbalance in the ratio of hydrogen to oxygen flow rates, causing significant degradation in stack performance and durability. A decline in stack performance was also observed over time due to the degradation of stack components. This phenomenon was consistently observed in individual unit cells. Based on these findings, it was emphasized that, in addition to optimizing the performance of each component during stack operation, it is important to optimize design and operating conditions for uniform flow rate control. Lastly, the developed silica composite membrane was assessed to have sufficient performance for application in actual fuel cell systems, exhibiting a performance of over 25 W based on maximum power.

• Neonatal Medicine
• /
• v.25 no.3
• /
• pp.131-135
• /
• 2018

Hyponatremia is defined as a plasma sodium concentration of <135 mEq/L. It is a common electrolyte imbalance in newborns. We report the case of a term neonate with cleft lip, cleft palate, imperforate anus, normal male karyotype, and chronic hyponatremia. On the 4th day of life, he showed hyponatremia (plasma sodium concentration 130 mEq/L) with low serum osmolality (275 mOsm/kg), high urine sodium (116.7 mEq/L), and high urine osmolality (412 mOsm/kg). His thyroid and adrenal functions were normal. Despite intravenous and oral sodium supplementation and hydrocortisone treatment, hyponatremia persisted. Brain magnetic resonance imaging showed normal results. He was diagnosed as having reset osmostat, a rare subtype of the syndrome of inappropriate secretion of antidiuretic hormone characterized by a subnormal threshold for antidiuretic hormone secretion, with hypotonic hyponatremia.

• Journal of Yeungnam Medical Science
• /
• v.31 no.1
• /
• pp.21-24
• /
• 2014

Clinical presentation of Bartter syndrome is similar to surrepitious vomiting or use of diuretics. Therefore, precise differential diagnosis of Bartter syndrome is crucial. We report a case of medullary nephrocalcinosis (MNC) induced by furosemide mimicking Bartter syndrome. A 55-year-old female patient visited our hospital with renal dysfunction on basis of hypokalemia and metabolic alkalosis. She had no history of hypertension or drug use except allopurinol and atorvastatin. She did not complain of nausea or vomiting on presentation and the serum magnesium level was normal. We performed ultrasonography, that showed MNC. For these reasons, we suspected Bartter syndrome and corrected the electrolyte imbalance. During outpatient follow up, we found that the patient had been taking 400 mg of furosemide daily for 30 years. We could diagnose furosemide induced MNC, and recommended to her to reduce the amount of furosemide.