• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.4
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• pp.365-379
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• 1994

Pool boiling experiments were carried out to study the effect of electric field on nucleate boiling heat transfer. CFC-11 and its alternative HCFC-123 were used as working fluids. Boiling on both single tube and a bundle of five tubes was investigated. Heat flux varied from 5 to $25kW/m^2$ while the applied voltage changed from 0 to 1kV. The results showed that at low heat flux where boiling was not present or very weak, electric field-induced forced convection helped increase the heat transfer coefficients of CFC-11 and HCFC-123 significantly(4-15 times increase). However, at higher heat flux, nucleate boiling of CFC-11 which is a highly dielectric fluid, was not affected significantly by the application of electric field. In contrast to CFC-11, even at high heat flux, nucleate boiling of CFC-11 which has a relatively larger electric conductivity than CFC-11, was vigorously increased up to 2-4 times. The additional power required to apply the electric field was 1-2% of the total power consumption by the heater. The increase in overall heat transfer coefficient of evaporators with HCFC -123 was about 40%, suggesting a considerable reduction in evaporator size with EHD technique.

• Journal of Korean Orthopaedic Sports Medicine
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• v.8 no.2
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• pp.102-108
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• 2009

Purpose: The purpose of this study is to report a result of the technique that reconstruct posterior cruciate ligament (PCL) and posterolateral corner (PLC) simultaneously using a fresh-frozen Achilles tendon allograft. Materials and Methods: Forty two patients (45 legs) underwent PCL and PLC reconstruction were included. There were 38 males and 4 females. Mean age was 39 years. Used graft was a fresh frozen Achilles tendon allograft, which was divided by two size, larger one (${\emptyset}$ 10 mm) for PCL reconstruction and smaller one (${\emptyset}$ 8 mm) for PLC reconstruction. Arthroscopic reconstruction of the PCL was performed using transtibial, single incision, and single bundle technique with 10mm fresh frozen Achilles allograft tendon first. After PCL reconstruction, reconstruction procedure for posterolateral instability was performed using modified figure of "8" technique using smaller gtaft. For clinical evaluation, range of motion, posterior drawer test, varus stress test, prone external rotation (dial) test, Lysholm score, Tegner activity scale and posterior stress radiograph were used. Mean follow up period was 25 months. Results: Preoperatively posterior drawer test was 5 cases in grade II and 40 cases in grade III posterior instability. At final follow-up 22 cases returned within normal condition, 18 cases grade I and 5 cases grade II posterior instability. Though all patients showed positive result over 10 degrees in dial and varus stress test preoperatively, but only 9 cases showed positive both test at final follow-up. The range of motion deficit over $10^{\circ}$ flexion was 3 cases. Lysholm score was improved from mean 50 preoperatively to mean 83(p<0.05) and Tegner activity scale improved from mean 2.1 preoperatively to mean 4.6(p<0.05). In posterior stress radiographs, posterior displacement was improve from mean 16mm preoperatively to 4.1mm after treatment(p<0.05). All patients had improved compared to their pre-operative status as measured by physical examination such as posterior drawer test, varus stress test, dial test. Conclusion: We had successful results by combined reconstruction of the PCL & PLC with a fresh frozen Achilles tendon allograft in patients with PCL and posterolateral rotatory instability at a time.