• Korean Journal of Materials Research
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• v.25 no.4
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• pp.196-201
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• 2015

This paper presents the impact of partial shading on $CuIn_xGa_{(1-x)}Se_2(CIGS)$ photovoltaic(PV) modules with bypass diodes. When the CIGS PV modules were partially shaded, the modules were under conditions of partial reverse bias. We investigated the characterization of the bypass diode and solar cell properties of the CIGS PV modules when these was partially shaded, comparing the results with those for a crystalline silicon module. In crystalline silicon modules, the bypass diode was operated at a partial shade modules of 1.67 % shading. This protected the crystalline silicon module from hot spot damage. In CIGS thin film modules, on the other hand, the bypass diode was not operated before 20 % shading. This caused damage because of hotspots, which occurred as wormlike defects in the CIGS thin film module. Moreover, the bypass diode adapted to the CIGS thin film module was operated fully at 60% shading, while the CIGS thin film module was not operated under these conditions. It is known that the bypass diode adapted to the CIGS thin film module operated more slowly than that of the crystalline silicon module; this bypass diode also failed to protect the module from damage. This was because of the reverse saturation current of the CIGS thin film, $1.99{\times}10^{-5}A/cm^2$, which was higher than that of crystalline silicon, $8.11{\times}10^{-7}A/cm^2$.

• Journal of Chest Surgery
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• v.7 no.1
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• pp.73-78
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• 1974

Influences on organ function were studied in animals during prolonged extracorporeal circulation with a bubble type of oxygenator. More than six hours of total cardiopulmonary bypass was performed under mild hypothermia by means of an extracorporeal circulation system in five dogs. Obtained results were summarized as follows. 1. The renal function was not so impaired seriously until four hours of extracorporeal circulation. However, there was more serious impairment of renal function in this study when extracorporeal circulation was carried out for a period of five hours or more. 2. There was gradual hepatic damage during extracorporeal circulation and the damage was more significant after bypass for a period of five to six hours. 3. There was a significant decrease in serum K during bypass, irrespective of the pump oxygenator prime with a high K solution. The reason for this is complex and due to many factors, however, it was evidently related to serum glucose levels during extracorporal circulation.

• Molecules and Cells
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• v.26 no.1
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• pp.5-11
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• 2008

Stalled DNA replication forks activate specific DNA repair mechanism called post-replication repair (PRR) pathways that simply bypass DNA damage. The bypassing of DNA damage by PRR prevents prolonged stalling of DNA replication that could result in double strand breaks (DSBs). Proliferating cell nuclear antigen (PCNA) functions to initiate and choose different bypassing pathways of PRR. In yeast, DNA replication forks stalled by DNA damage induces monoubiquitination of PCNA at K164, which is catalyzed by Rad6/Rad18 complex. PCNA monoubiquitination triggers the replacement of replicative polymerase with special translesion synthesis (TLS) polymerases that are able to replicate past DNA lesions. The PCNA interaction motif and/or the ubiquitin binding motif in most TLS polymerases seem to be important for the regulation of TLS. The TLS pathway is usually error-prone because TLS polymerases have low fidelity and no proofreading activity. PCNA can also be further polyubiquitinated by Ubc13/ Mms2/Rad5 complex, which adds an ubiquitin chain onto monoubiquitinated K164 of PCNA. PCNA polyubiquitination directs a different PRR pathway known as error-free damage avoidance, which uses the newly synthesized sister chromatid as a template to bypass DNA damage presumably through template switching mechanism. Mammalian homologues of all of the yeast PRR proteins have been identified, thus PRR is well conserved throughout evolution. Mutations of some PRR genes are associated with a higher risk for cancers in mice and human patients, strongly supporting the importance of PRR as a tumor suppressor pathway.

• Journal of Chest Surgery
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• v.25 no.5
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• pp.526-532
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• 1992

The effect of cardiopulmonary bypass on platelet count and function was studied in 20 patients who underwent cardiac operation from April 1991 to August 1991 at the Department of thoracic and Cardiovascular Surgery, School of Medicine, Keimyung University. Ten patients were perfused with a bubble oxygenator, 10 with a membrane oxygenator. During and after bypass, platelet counts decreased in both groups and significantly reduced in those perfused with a bubble oxygenator. All 20 patients studied for platelet functions had an abnormal postoperative aggregation response to collagen and epinephrine, but no significant difference in both groups. One hour after bypass, bleeding times increased in both groups but did not differ significantly between groups. Postoperative 24 hour blood losses were significantly higher in patients perfused with a membrane oxygenator. Platelet damage and postoperative blood loss are less severe after cardiopulmonary bypass performed with a membrane oxygenator than with a bubble oxygenator.

• Journal of Chest Surgery
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• v.17 no.2
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• pp.189-196
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• 1984

Although the conventional methods of cardiopulmonary bypass for open heart surgery have been employed, it has been usual method to repair of congenital heart disease in infancy using deep hypother-mia and circulatory arrest technique. In 1980, we reported total correction of congenital heart disease using surface induced hypothermia-total circulatory arrest and rewarming with limited cardiopulmonary bypass. in 1981, three patients below 10 kilogram, who had ASD and PDA, and two of VSD with pulmonary hypertension were operated on using simple deep hypothermia without cardiopulmonary bypass. During surface cooling, there were no ventricular fibrillation and arrhythmia. There were no difficulties to resuscitate the heart. Postoperative respiratory and neurologic complication were not occurred. Follow up examination for two to three years gave no evidence of cerebral damage due to circulatory arrest.

• Journal of Chest Surgery
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• v.32 no.11
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• pp.971-977
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• 1999

Background: Immunologic and inflammatory responses of cardiopulmonary bypass(CPB) influence postoperative mortality and morbidity with multiple organ injury. It has been reported that ischemia/reperfusion induced-myocardial injury during CPB is causative of release of inflammatory cytokines such as interleukin-6(IL-6) and tumor necrosis factor-$\alpha$ (TNF-$\alpha$). The purpose of this study was to detect the time course of the activated cytokine and troponin-T(TnT), and to examine the correlation between such parameters during CPB. Material and Method: The serial samples were collected from arterial blood via radial arterial catheter in 23 patients who are underwent open heart surgery (OHS) with CPB, the IL-6, TNF-$\alpha$ and TnT were checked. Result: \circled1 IL-6, TNF$\alpha$- and TnT concentration increased significantly during CPB with a peaking level of CPB-off (p 0.05). \circled2 IL-6 had highly positive correlation with aortic cross clamping time and total bypass time(r=0.80, 0.78; p 0.05, respectively). \circled3 There was no correlation among IL-6, TNF-$\alpha$ and TnT. Conclusion: In conclusion, these data showed that elevated production of serum IL-6 during CPB was attributable to ischemia/reperfusion induced-myocardial damage. IL-6 will become a new and sensitive biological marker in assessment of myocardial damage during OHS with CPB. However, further studies will be needed to apply IL-6 in more patient population.

• Journal of the Korean Solar Energy Society
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• v.37 no.4
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• pp.1-11
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• 2017

Most PV modules are fabricated by 6 cell-strings with solar cells connected in series. Moreover, bypass diodes are generally installed every 2 cell-strings to prevent PV modules from a damage induced by current mismatch or partial shading. But, in the case of special purpose PV module, like as BIPV (Building Integrated Photovoltaic), the number of cell-strings per module varies according to its size. Differ from a module employing even cell-strings, the configuration of bypass diode should be optimized in the PV module with odd strings because of oppositely facing electrodes. Hence, in this study, electrical characteristics of special purposed PV module with odd string was empirically and theoretically studied depending on arrangement of bypass diode. Here, we assumed that PV module has 3 strings and the number of bypass diodes in the system varies from 2 to 6. In case of 2 bypass diodes, shading on a center string increases short circuit current of the module, because of a parallel circuit induced by 2 bypass diodes connected to center string. Also, the loss is larger, as the shading area in the center string is enlarged. Thus, maximum power of the PV module with 2 bypass diode decreases by up to 59 (%) when shading area varies from 50 to 90 (%). On the other hand, In case of 3 and 6 bypass diodes, the maximum power reduction was within about 3 (W), even the shading area changes from 50 to 90 (%). As a result, It is an alternative to arrange the bypass diode by each string or one bypass diode in the PV module in order to completely bypass current in case of shading, when PV module with odd string are fabricated.

• Steel and Composite Structures
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• v.34 no.4
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• pp.487-497
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• 2020

During the last few decades, fluid viscous dampers have been significantly improved in terms of performance and reliability. Viscous dampers dissipate the input energy into heat and the increased temperature may damage internal seals of the damper. As a result, thermal compensation is crucial for almost all fluid viscous dampers. In this study, while referring to the main working principles of the recently developed bypass viscous damper in Iran, a comprehensive case study is conducted on a RC building having diagonal braces equipped with such viscous dampers. Experimental results of a small-scale bypass viscous damper is presented and it is shown that the currently available simplified Maxwell models can simulate behavior of the bypass viscous damper with good accuracy. Using a case study, contribution of bypass viscous dampers to seismic behavior of structural and non-structural elements are investigated. A designed procedure is adopted to increase damping ratio of the building from 3% to 15%. In this way, reductions of 25% and 13% in the required concrete and steel rebar materials have been achieved. From nonlinear time history analyses, it is observed that bypass viscous dampers can greatly improve seismic behavior of structural elements and non-structural elements.

• Transactions on Electrical and Electronic Materials
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• v.17 no.6
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• pp.359-362
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• 2016

In the PV (Photovoltaic) power system, a junction box collects the DC voltage generated from the PV module and transfers it to the PCS (power conditioning system). The junction box prevents damage caused by the voltage difference between the serially connected PV modules and provides convenience while repairing or inspecting the PV array. In addition, the junction box uses the diode to protect modules from the inverse current when the PV power system and electric power system are connected for use. However, by using the reverse blocking diode, heat is generated within the junction box while generating electric power, which decreases the generating efficiency, and causes short circuit and electric leakage. In this research, based on the purpose of improving the performance of the PV module by decreasing the heat generation within the junction box, a junction box with a built-in bypass circuit was designed/manufactured so that a certain capacity of current generated from the PV module does not run through the reverse blocking diode. The manufactured junction box was used to compare the electric power and heating power generated when the circuit was in the bypass/non-bypass modes. It was confirmed that the electric power loss and heat generation indicated a decrease when the circuit was in the bypass mode.

• Biomedical Science Letters
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• v.10 no.3
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• pp.237-243
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• 2004

In recent, many cardiac centers have preferred off-pump coronary artery bypass grafting (CABG) to on-pump CABG to prevent the adverse effects of cardiopulmonary bypass. The present study was performed to prove beneficial effects of off-pump CABG. Sixty adult patients scheduled for elective CABG were randomly assigned to On-pump group (n=30) or Off-pump group (n=30). Arterial blood samples were drawn before and after the operation (Pre-OP and Post-OP, respectively) for measuring CBC, prothrombin time, activated thromboplastine time, blood gas analysis, creatine kinase-MB (CK-MB) level, and lactate dehydrogenase (LDH) level. Perioperative parameters including heparin and protamine usages, complications, blood components usages, blood loss, ventilation and ICU-staying time, and hospitalization were also evaluated. Platelet count at Post-OP was high in Off-pump group whereas CK-MB and LDH levels were low compared with On-pump group. Off-pump group had significantly lower heparin and protamine usages, lower total leukocyte count, higher hematocrit and hemoglobin levels, less blood loss, lower usages of blood components, shorter ventilation and ICU-staying time, and lower incidence of pleural effusion than On-pump group. Other variables did not significantly differ between two groups. These results showed that Off-pump CABG was a satisfactory technique with less inflammatory reaction, less cardiac damage, less postoperative complications, and less cost.