• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.6
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• pp.493-502
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• 2002

During the defrosting process, the temperature in the cabinet of a showcase becomes high as compared to the setting point, which is not desirable for stored foods or materials. It is necessary to develop a more efficient defrosting method to prevent large temperature fluctuation. In this study, the performance of a showcase refrigeration system with three evaporators is investigated by employing a hot-gas bypass defrosting technology in the system under frosting and defrosting conditions. The operating characteristics are compared with those for the on-off defrosting method that has been widely used in current products. As a result, the hot-gas bypass defrosting method shows higher refrigerating capacity and less temperature fluctuation than the on-off method under frosting/defrosting conditions, while the power input is relatively high for the hot-gas bypass method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.6
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• pp.319-325
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• 2009

The purpose of this study is to investigate the performance characteristics of a bypass two-circuit refrigerator. A bench scale refrigeration system was designed and constructed to estimate possible performance improvement of the bypass two-circuit refrigerator. The experiments were conducted in the bench scale refrigeration system by varying capacity of the condenser and refrigerant charge amount with an adoption of a refrigerant storage vessel. The COPs of the bypass two-circuit refrigeration system in the refrigerator and freezer (RF)-mode and freezer(F) only-mode were increased by 10% and 17%, respectively, with increasing the capacity of the condenser. Besides, the COP of the system in the F only-mode was increased by 10% by adopting the refrigerant storage vessel.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1265-1268
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• 2009

In this paper, the effect of a flow barrier and bypass on the cooling performance for a straight fin heat sink is presented. Both side directions and upward direction of bypass are controlled using various ducts which have different width and heights. In addition, a flow barrier is used to control flow toward heat sink. Through experiments, the distance from leading edge of a heat sink to a flow barrier is varied for various bypasses under fixed volume flow rate condition. This study shows possibility to improve cooling performance when bypass and a flow barrier exist.

• 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.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.54-59
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• 2019

The main objective of nuclear reactor safety is to maintain the nuclear fuel in a thermally safe condition with enough safety margins during normal operation and anticipated operational occurrences. In this research, core flow bypass is studied under the conditions of the unavailability of safety systems. As core bypass occurs, the core flow rate is assumed to decrease exponentially with a time constant of 25 s to new steady state values of 20, 40, 60, and 80% of the nominal core flow rate. The thermal hydraulic code PARET is used through these calculations. Reactor thermal hydraulic stability is reported for all cases of core flow bypass.

• Journal of Korean Neurosurgical Society
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• v.65 no.4
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• pp.603-608
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• 2022

Vertebral artery (VA) occlusion is frequently encountered, usually without acute ischemic injury of the brain. However, when it is accompanied by hypoplasia or stenosis of the opposite VA, brain ischemia may develop due to insufficient collateral supply. Both hemodynamic instability and embolic infarction can occur in VA occlusion, which may cause severe symptoms in a patient. Extracranial carotid-VA bypass should be considered for symptomatic VA occlusion patients, especially when the patient has repeated ischemic brain injuries. In this report, the cases of three extracranial carotid-VA bypass patients are introduced, along with a brief description of the surgical techniques. All three cases were treated with different bypass methods according to their disease location.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.429-435
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• 2011

In this study the operational characteristics of the temperature control system between an on-offemployed cooler and a bypass type cooler is analyzed. Currently an on-off controller employed coolerwhich is the industry's leading type on the market for industrial coolers is used. The new type cooler isused a bypass controller at discharge gas. The COP of the bypass controlled cooler with discharge gas is at least 8% higher than the on-off controlled cooler. The maximum COP difference is about 20%. Based on the results, the bypass control with discharge gas shows the possible temperature control with high precision.

• Journal of Chest Surgery
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• v.46 no.1
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• pp.84-87
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• 2013

A 60-year-old man visited the outpatient clinic due to one month of recurrent exertional chest pain. Eleven years earlier he had undergone off-pump coronary artery bypass grafting using bilateral internal thoracic artery (ITA) Y-composite grafts based on the left ITA. Preoperative coronary angiography showed patent distal graft anastomoses and visualized the left ITA retrogradely. The arch aortography revealed near-total occlusion of the left subclavian artery at the level of the ostium. The patient underwent left carotid-to-subclavian artery bypass grafting using a 6 mm vascular conduit. Postoperative computed tomographic angiography revealed a patent bypass conduit between the left common carotid artery and left subclavian artery. The patient was discharged on postoperative day 4 with no symptoms or signs of myocardial ischemia.

• Journal of Chest Surgery
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• v.26 no.12
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• pp.920-925
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• 1993

Extra-anatomic bypass was proposed by Freeman in 1952 and has been used for patient with lower extremity arterial occlusion who had very high operative risk, especially elderly or severly illed patient.We had performed 14 cases of extra-anatomic bypasses from Jan. 1991 till July 1993 and having been following up them. Their results were summarized as follow. Among total 14 patients, 13 was male. Their mean age was 64.8 years old, ranged from 48 to 80. The most common complaint was pain on lower limb and they visited hospital 6.1 months in average after onset of symptom. Frequently, they were associated with systemic diseases such as generalized atherosclersis, hypertension, diabetes mellius, etc. Axillary artery was used as donor artery in 8 cases and crossover femoro-femoral or femoro-popliteal bypass was performed in 6 cases. Postoperative complications were notedd in 8 cases so their morbidity rate was 42.8%. Except for two contraindicated cases, one or more anticoagulants were used routinely . Among them, combined use of aspirin and persantine was most commonly applied.After bypass graft, nine cases were occluded beteween 10 and 53 months. So their average duration of freedom from reocclusion was 35.7 months and 3-year patency rate was 63%.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.5
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• pp.169-175
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• 2013

CRDi technology of diesel engine was developed from in the early 2000s due to a need to increase fuel efficiency and environment care. Especially, high-pressure fuel injection system in CRDi system which has a fuel injection unit including an injector, a fuel pump and common-rail, etc. becomes possible to make the exhaust gas clean as well as power improvement. In this study, comparison of dynamic characteristics of servo-hydraulic piezo-driven injector with 3-way and bypass-circuit type was analyzed by using the AMESim code. As results of this study, it found the bypass-circuit inside servo-hydraulic piezo injector can cause a faster injection response than that of the 3-way type. Also it was shown that bypass-circuit type had better control capability due to hydraulic bypass system.