• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2002-2010
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• 2024

Korea Atomic Energy Research Institute (KAERI) has operated an integral effect test facility, the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS), with reference to the APR1400 (Advanced Power Reactor 1400) for tests for transient and design basis accidents simulation. A test for a loss of coolant accident (LOCA) at the top of the reactor pressure vessel (RPV) had been conducted at ATLAS to address the impact of the loss of safety injections (LSI) and to evaluate accident management (AM) actions during the postulated accident. The experimental data has been utilized to validate system analysis codes within a framework of the domestic standard problem program organized by KAERI in collaboration with Korea Institute of Nuclear Safety. In this study, the test has been analyzed by using thermal-hydraulic system analysis codes, MARS-KS 1.5 and TRACE 5.0 Patch 6, and a comparative analysis with experimental and calculation results has been performed. The main objective of this study is the investigation of the thermal-hydraulic phenomena during a small break LOCA at the RPV upper head with the LSI as well as the predictability of the system analysis codes after the AM actions during the test. The results from both codes reveal that overall physical behaviors during the accident are predicted by the codes, appropriately, including the excursion of the peak cladding temperature because of the LSI. It is also confirmed that the core integrity is maintained with the proposed AM action. Considering the break location, a sensitivity analysis for the nodalization of the upper head has been conducted. The sensitivity analysis indicates that the nodalization gave a significant impact on the analysis result. The result emphasizes the importance of the nodalization which should be performed with a consideration of the physical phenomena occurs during the transient.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1337-1345
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• 2011

In pressurized water reactors (PWRs), the reactor pressure vessel (RPV) upper head contains numerous control rod drive mechanism (CRDM) nozzles. In the last 10 years, the incidences of cracking in alloy 600 CRDM nozzles and their associated welds has increased significantly. Several axial and circumferential cracks have been found in CRDM nozzles in European PWRs and U.S. nuclear power plants. These cracks are caused by primary water stress corrosion cracking (PWSCC) and have been shown to be driven by welding residual stresses and operational stresses in the weld region. Therefore, detailed finite-element (FE) simulations for the Korea Nuclear Reactor Pressure Vessel have been conducted in order to predict the magnitudes of the weld residual stresses in the tube materials. In particular, the weld residual stress results are compared in terms for nozzle location, geometry factor$r_o$/t, geometry of fillet, and adjacent nozzle.

• Journal of Haehwa Medicine
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• v.8 no.2
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• pp.289-298
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• 2000

The result were obtained as follow: 1. Bladder Meridian has been used most frequently and next to Kidney Meridian has been used many time at the rate of acupuncture points. 2. Bladder Meridian has been used most frequently and next to Stomach Meridian, Kidney Meridian, Conception vessel have been used many time at the rate of frequency of used acupuncture points. 3. The acupuncture points at Lower extremity has been used most frequently and next to the point at back, chest and abdomen, upper extremity, head have been used many time. 4. The point of Ji Gu has been used most frequently and next to Dae Jang Su, Jock Sam Li, Cheon Chu, Jo Hae have been used many time. 5. In herb-medication, Seung Gi Tang has been used most frequently and next to Bi Yack Hwan, Ma In Hwan have been used many time.

• Archives of Reconstructive Microsurgery
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• v.9 no.1
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• pp.1-5
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• 2000

The microsurgical reconstruction is necessary for elderly patients to treat severe trauma and head and neck tumor. The aim of this study is to analyze the risks of microvascular surgery and whether or not happening of more complication in elderly patients who are older than 60 years old and to suggest the solution of the complication. The retrospective study included 41 elderly patients who underwent treatment of 44 microsurgical reconstructions among total 271 cases of microsurgical reconstruction from July, 1988 to December, 1998. Their ages ranged from 61 years to 79 years. There were 26 males and 15 females. The involved sites were 23 head and necks, 13 upper gastrointestinal tracts, 3 lower extremities, 1 chest and 1 sacral region. The causes of microsurgical reconstruction were 36 head and neck tumors, 2 radionecrosis, 2 traumas and 1 melanoma in lower limb. The used flaps were 14 radial forearm flaps, 13 jejunal flaps, 10 latissimus dorsi muscle flaps, 3 rectus abdominis muscle flaps, 2 lateral arm flaps, 1 scapular flap, and 1 iliac osteocutaneous flap. They had medical problems which were 29 tobacco abuse, 14 hypertensions, 13 alcohol abuse, 10 chronic obstructive pulmonary diseases, 7 diabetes mellituses, 3 ischemic heart diseases. All patients have had successful results without specific complications except 3 cases of free flap failure and 3 perioperative death. The causes of 3 flap failures were 2 flap necrosis due to arterial insufficiency and 1 flap loss due to secondary infection. All of these cases were treated with secondary free flap surgery. However 3 patients died perioperatively due to 2 respiratory arrests and 1 sepsis. It was not related to operate microsurgical reconstruction itself, but was correlated with the complication of postoperative care after head and neck surgery. We conclude that plastic surgeons consider the importance of prevention of expected complication as thorough analysis of operative risk factor and appropriate treatment. We had to select the donor and recipient vessel appropriately to perform successful microsurgery in elderly patients and consider vein graft and end-to-side anastomosis to reduce complication if necessary. In addition, we emphasize the importance of pre, peri and postoperative care in head and neck cancer patients to reduce postoperative complication and morbidity.

• Archives of Reconstructive Microsurgery
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• v.9 no.1
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• pp.15-22
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• 2000

One hundred & seventy four consecutive free-flap transfers were reviewed to analyze distribution of the type of reconstructions, kinds of donor flaps as well incidence of complications. The role of emergent exploration and the effect of preoperative wound conditions in flap survival were evaluated. Free flap transfer for head and neck reconstruction was most common as 93 cases, followed by for upper extremity of 30 cases, for lower extremity 30 cases, 18 penile reconstructions and for trunk & breast 3 cases. Nine flaps exhibited signs of ciruclatory insufficiency between 5 hours and 7 days. Three were managed conservatively with ultimate partial necrosis of the flaps. Eight flaps required return to the operating room. On exploration, early arterial occlusion was revealed in 1 flap, late arterial occlusion in 2 flaps, early venous occlusion in 1 flap, late venous thrombosis in 2 flaps, prolonged venous spasm in 1 and hematoma in 1 flap. The average time from the first abnormal examination to exploration was 2.6 hours. There were no false-positive explorations. Four free flaps failed in spite of the correction of the cause of circulatory compromise. The remaining 4 flaps were salvaged following the correction the casuse. Recipient vessel problems such as irradiation and infection were the most common cause of circulatory crisis. Among the eight flaps requiring return to the operating room, single vein was anastomosed in three flaps and two veins in the remaining five. In the totally failed four flaps only single vein was anastomosed in three cases. The results of this study demonstrate the efficacy of clinical monitoring and the role of early exploration. Precautious selection of recipient vessels and two vein anastomosis are recommended for safe and better prognosis.

• Laser Solutions
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• v.14 no.2
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• pp.8-12
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• 2011

As the aged population grows around the world, many medical instruments and devices have been developed recently. Among the devices, a drug delivery stent is a medical device which requires precision machining. Conventional drug delivery stent has problems of residual polymer and decoating because the drug is coated on the surface of stent with the polymer. If the drug is impregnated in micro hole array on the surface of the stent, the problem can be solved. Micro sized holes are generally fabricated by laser machining; however, the fabricated holes do not have an enough aspect ratio to contain the drug or a good surface finish to deliver it to blood vessel tissue. To overcome these problems, we propose a vibration-assisted machining mechanism with PZT (Piezoelectric Transducers) for the fabrication of micro sized holes. If the mechanism vibrates the eyepiece of the laser machining head, the laser spot on the workpiece will vibrate vertically because objective lens in the eyepiece shakes by the mechanism's vibration. According to the former researches, the vibrating frequency over 20kHz and amplitude over 500nm are preferable. The vibration mechanism has cylindrical guide, hollowed PZT and supports. In the cylinder, the eyepiece is mounted. The cylindrical guide has upper and low plates and side wall. The shape of plates and side wall are designed to have high resonating frequency and large amplitude of motion. The PZT also is selected to have high actuating force and high speed of motion. The support has symmetrical and rigid characteristics.

• Archives of Reconstructive Microsurgery
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• v.16 no.1
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• pp.1-5
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• 2007

The purpose of this article to evaluate the availability of the rectus femoris flap in Korean subjects. Material and Methods is that Cadaveric dissections were done on 51 femoral triangles of 26 cadevers. We measured the length of the direct head of rectus femoris from anterior superior iliac spine to patella upper pole, ASIS to lateral border of femoral nerve, and entry point of femoral nerve and vessel branches to rectus. Usually, there were three terminal branches to rectus femoris from the femoral nerve. The entry point of the first branch was at the proximal $17.5{\sim}31.4%$ portion of the rectus femoris. The second and the third branch entered at the proximal $22.5{\sim}40.7%$ and $26.3{\sim}42.3%$, respectively. The vessel entry was at $20.2{\sim}37.3%$. The length from ASIS to femoral nerve was $3.5{\sim}8.5\;cm$. Among the 51 rectus femoris muscles, 44 had one nutrient artery, and 7 had 2 nutrient arteries. The nutrient artery originated from the descending branch of the lateral femoral circumflex artery in 18(40.9%) cases, directly from the lateral femoral circumflex artery in 8(18.0%) cases, and from proximal(6 cases, 13.6%) and distal(12 cases, 27.3%) portion of the deep femoral artery. The average length of the nutrient artery was 29.8 mm and the width was 2.14 mm. The point where it meets the main feeding artery of the rectus femoris was $9.0{\sim}15.0\;cm$ from the ASIS. In all cases, the main artery's entrance was proximal to the first nerve branch. Conclusion is that rectus femoris has available data for functional flap.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1115-1130
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• 2012

In nuclear power plants, the reactor pressure vessel (RPV) upper head control rod drive mechanism (CRDM) penetration nozzles are fabricated using J-groove weld geometry. Recently, the incidences of cracking in Alloy 600 CRDM nozzles and their associated welds have increased significantly. The cracking mechanism has been attributed to primary water stress corrosion cracking (PWSCC), and it has been shown to be driven by welding residual stresses and operational stresses in the weld region. The weld-induced residual stress is the main factor contributing to crack growth. Therefore, an exact estimation of the residual stress is important for ensuring reliable operation. This study presents the residual stress computation performed for an RPV CRDM penetration nozzle in Korea. Based on two and three dimensional finite element analyses, the effect of welding variables on the residual stress variation is estimated for sensitivity analysis.