• KSTLE International Journal
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• 제10권1_2호
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• pp.27-32
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• 2009

In this study, fretting wear tests of nuclear fuel rods have been performed by using two kinds of spacer grid springs with a concave and a convex shape in room temperature dry and distilled water conditions. The objectives were to examine the variation of the wear mechanism with increasing fretting cycles and to evaluate the difference of the wear debris detachment behavior at each test environment. From the test results, the wear volume of each spring condition increased with increasing fretting cycles regardless of the test environments. However, the wear rate did not show a regular tendency and apparently changed with increasing fretting cycles. This is because the formation of the wear particle layer and/or the variation of the contact condition between the fuel rod and spring surfaces could affect a critical plastic deformation for detaching the wear debris. Based on the test results, the relationship between the wear behavior of each spring shape and test environment condition, and the variation of the surface characteristics are discussed in detail.

• Journal of Advanced Marine Engineering and Technology
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• 제17권2호
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• pp.36-43
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• 1993

Real quality and axial void fraction distribution of subcooled refrigerant flow is very important to predict the heat transfer rate and pressure drop in the design of refrigerating system. In the subcooled boiling region, the liquid bulk temperature is still below the corresponding saturation temperature. But beyond the net vapor generation point, bubble detachment is occured actively from the vapor layer formed on the wall. A reliable method to predict the vapor fraction from the liquid bulk temperature is suggested in this paper. And also the actual quality of the subcooled R-113 flow is calculated in the range of 261-1239kg/$m^2$s mass velocity and 10-30K subcooling.

• 설비공학논문집
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• 제13권8호
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• pp.720-729
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• 2001

The effect of vapor flow direction on falling film heat transfer was experimentally investigated by using water. Parallel flow (both water and vapor downwards) showed higher heat exchange performance than counterflow(downward water and upward vapor). The difference became significant as the vapor flow rate was increased. It is supposed that the uprising vapor disturbs the solution film flow and heat transfer is reduced by uneven distribution or detachment of water film.

• Corrosion Science and Technology
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• 제18권5호
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• pp.190-195
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• 2019

SA508 low-alloy steel for a reactor vessel was exposed to primary water in a pressurized water reactor (PWR) plant because the cladding layer of type 309 stainless steel for the RPV was removed, due to an accident in which the detachment of the thermal sleeve occurred. The major advantage of the electrochemical deposition (ECD) Ni plating technique is that the reactor pressure vessel can be repaired without significant thermal effects, and Ni has solid corrosion resistance that can withstand boric acid. The corrosion rate assessment of the damaged part was performed, and its trend was analyzed. Essential variables of the Ni plating for repair of the damaged part were derived. These conditions are applicable variables for the repair plating device, and have been carefully adjusted using the repair plating device. The process for establishing ASME technical standards called Code Case N-840 is described. The process of developing Ni-plating devices, and the electroplating procedure specification (EPS) are described.

• Journal of Electrochemical Science and Technology
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• 제14권4호
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• pp.349-360
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• 2023

This study investigated the tri-metallic galvanic coupling of different metals in the tubes, fillers, and fins of a heat exchanger. The goal was to prevent corrosion of the tubes using the fin as a sacrificial anode while ensuring that the filler metal has a more noble potential than the fin, to avoid detachment. The metals were arranged in descending order of corrosion potential, with the noblest potential assigned to the tube, followed by the filler metal and the fin. To address a reduction in protection current of the fin, the filler metal was modified by adding Zn to decrease its corrosion potential. However, increasing the Zn content of filler metal also increases its corrosion current. The study examined three different filler metals, considering their corrosion potential, and kinetics. The results suggest that a filler metal with 1.5 wt.% Zn addition is optimal for providing cathodic protection to the tube while reducing the reaction rate of the sacrificial anode.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제15권2호
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• pp.123-128
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• 1993

For the purpose of studying postsurgical stability of mandibular prognathism, 18 patients(8 men and 10 women) were selected who underwent sagittal split ramus osteotomy and lateral cephalograms taken preoperatively, immediate postoperatively, and over 6-month follow-up were traced and analysed. The following results were obtained. 1. Average magnitude of setback vas 11.0mm, and aberage relapse was 3.0mm, so the rate of relapse was 27%. 2. Magnitude of mandibular setback contributed to relapse. 3. The patients of less than 10mm setback showed average 10% of relapse rate, and it was of little clinical significance. 4. Proper detachment of pterygomasseteric sling prevention of clockwise rotation of proximal segment and rigid fixation are recommended for the better postoperative stability.

• Journal of Chest Surgery
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• 제18권2호
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• pp.157-164
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• 1985

Our series comprised 68 patients of ventricular septal defect who underwent open heart surgery at the Department of Thoracic and Cardiovascular Surgery, School of Medicine, Kyungpook National University, from January, 1980 to September, 1984. Of the 68 patients, 47 patients were male [69.1%] and 21 patients were female [30.9%]. Their age ranged from 3 years to 27 years, and the mean age was 10.1 years. Upon Kirklin`s anatomical classification, type I constituted 29.4%, type II 69.1%, type III 1.5%, and type IV 1%. The cardiac anomalies associated with ventricular septal defect were 21 in all; 5 PS, 4 Aortic insufficiency, 2 ASD, 4 Patent foramen ovale, and 1 Patent ductus arteriosus. Upon the data of cardiac catheterization, most of the patients had Qp/Qs of 1.4-1.8, Pp/Ps of 0.25 or less and Rp/Rs of 0.25 or less. There was no significant correlationship between the rate of operative complication & mortality and the increase of Qp/Qs, Pp/Ps, and Rp/Rs. The values of Qp/Qs, Pp/Ps and Rp/Rs were correspondingly increased according to increment of the defect size. 20 patients developed postoperative complications, such as 4 acute respiratory failure, 3 reexploration due to massive bleeding, 1 low cardiac output, 1 patch detachment, and 2 air embolism. Operative mortality rate was 7.4% [5 cases] among 68 patients.

• 대한금속재료학회지
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• 제47권10호
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• pp.667-674
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• 2009

High temperature wear of STD 61 tool steels sliding against the Al-9%Si coated steels used for hot press forming has been studied in comparison with that of the tool steels sliding against the uncoated steels. Wear tests have been performed using a pin-on-disc configuration under an applied normal load of 50N for 20 min with heating the coated and uncoated steels up to 800$^{\circ}C$. It was found on the worn surface of the STD 61 tool steels sliding against the Al-9%Si coated steels that the formation of the glazed layers containing Al transferred from the coated tribopair may contribute to a reduction of the coefficient of friction, and detachment in part occur due to delamination wear, resulting in higher specific wear rate. On the other hand the Fe-oxide wear debris entrapped on the softer surface of the uncoated steels can act as a tribosurface, leading to decreased adhesive wear of the STD 61 tool steels, resulting in a lower specific wear rate.

• 한국가스학회지
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• 제25권1호
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• pp.7-13
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• 2021

재액화 드럼은 과냉각된 LNG를 증발가스에 직접 분사하기 위해 상부에 스프레이 노즐을 설치하고, 기액 분리가 용이하도록 데미스터를 설치한 제품으로, 소형 재액화 설비의 재액화 효율을 높이기 위해 개발한 제품이다. 드럼의 상온 내압기밀시험에서는 설계압력의 1.5배 이상의 압력에서도 누설(Leak)이 없었으나, 단열성능시험 중 온도변화에 따른 수축/팽창으로 인해 볼트풀림 현상이 발생하였다. 제품의 지속적인 사용을 위해 플랜지 결합부의 단열 시공은 탈부착이 가능하도록 개발하였으며, 기존 단열과의 열침입량 비교 결과 드럼 내 유입 유량 대비 매우 미미함을 확인하였다.

• Parasites, Hosts and Diseases
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• 제45권2호
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• pp.153-156
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• 2007

The small intestines of 6 species of rodents and 1 species of insectivore were examined seasonally for Plagiorchis muris infection in 3 different localities in northern Gyeonggi-do (Province), near the demilitarized zone (DMZ). A total of 1,496 animals, including 1,366 Apodemus agrarius, 54 Crocidura iasiura (insectivore), 32 Mus musculus, 28 Micronytus fortis, 9 Eothenomys regulus, 6 Micronys minutus, and 3 Cricetulus triton, were live-trapped at Yeoncheon-gun (n = 351), Paju-shi (804) and Pocheon-gun (343) at 3-mo intervals from December 2004 to September 2005. A total of 1,647 P. muris were collected from 72 (5.3%) A. agrarius. The infection rate was the high-est in Pocheon-gun (8.2%), followed by Yeoncheon-gun (5.0%) and Paju-shi (4.2%). A higher infection rate was observed in A. agrarius captured during September (19.4%) than those captured during December (3.0%), June (2.6%), or April (0%). However, the worm burden was the highest in June (av. 32.1/animal), followed by September (24.7), December (4.0), and April (0). None of the other animal species were found infected with P. muris. The results reveal that A. agrarius is a natural definitive host for P. muris, and infection rates and worm burdens vary seasonally and geographically.