• Applied Science and Convergence Technology
• /
• 제24권5호
• /
• pp.125-131
• /
• 2015

We investigated the thermal characteristics of rotating anode X-ray tube to develop it for digital radiography by using computer simulation. The target which is the area of the anode struck by electrons is the most important component to get a long life of X-ray tube. So we analyze the thermal characteristics of the target and rotor assembly according to their emissivity by using ANSYS transient thermal simulation and then compare with the measured data of the target temperature operating in aging process of X-ray tube. Especially, keeping the lead coated layer as the role of metal lubricant on ball bearing enables to prevent the noise in rotating anode. The simulation result showed that its temperature was under the melting point of the lead in X-ray tube for digital radiography with 1.2 mm large focal spot 0.6 mm small focal spot and 150 kV tube voltage. We also investigated the relationship between the diameter of the anode shaft and the temperature of the anode and rotor assembly. It has been confirmed that the smaller anode shaft could be good for the rotor thermal characteristics.

• Tribology and Lubricants
• /
• 제24권6호
• /
• pp.362-367
• /
• 2008

Tubes in nuclear steam generators are held up by supports because the tubes are long and slender. Fluid flows of high-pressure and high-temperature in the tubes cause oscillating motions between tubes and supports. This is called as FIV (flow induced vibration), which causes fretting wear in contact parts of tube-support. The fretting wear of tube-support can threaten the safety of nuclear power plant. The tube and support materials were Inconel 690 and STS 409. The wear tests were conducted in various environments, which are in water without flow, in flowing water and in flowing water with air. The results showed that the flow of water influenced on the wear-life of tube. The wear-life of tube decreased in water flow as compared with wear-life in stationary water.

• 한국압력기기공학회 논문집
• /
• 제7권4호
• /
• pp.51-56
• /
• 2011

Steam generator is one of the main equipments that affect safety and long term operation in nuclear power plants. Fluid flows inside and outside of the steam generator tubes and induces vibration. To prevent the vibration the tubes are supported by AVB (anti vibration bar). When the steam generator tube contact to AVB, it is damaged by the accumulation of wear and corrosion. Therefore studies are required to determine the effects of the gap between the steam generator tube and AVB. In order to obtain the stress and the displacement distributions of the steam generator tube, three dimensional finite element analyses were performed by using the commercial program ANSYS. Using the calculated the stress and the displacement distributions, the static residual strength of the steam generator tube can be evaluated. The results show that the stress and displacement of the steam generator tube increase significantly compared with the results from a zero-gap model.

• 한국군사과학기술학회지
• /
• 제12권1호
• /
• pp.24-28
• /
• 2009

In this study, we investigated whether the anhysteretic demagnetization process would be applicable to remove a complicated magnetization of a steel tube as a part of the experimental earlier study for a deperming of naval vessel. The magnetic tube used in this study was a 10cm-long and 1cm-diameter steel tube, and magnetized with a E-shape ferrite core to form a nonuniform magnetization in it. In the anhysteretic demagnetization process, a dc magnetic field applied along the longitudinal direction of the tube decreased from ${\pm}$3kA/m to zero-field with the step of ${\pm}$300A/m. At the same time, an ac bias magnetic field with the frequency of 60Hz and the field intensity of 300A/m was excited along the circumstantial direction of the tube. It was found that the anhysteretic process was useful to demagnetize a small-object like a steel tube from the experimental results showing the residual magnetization reduced over 90%.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 12th Asian Congress of Fluid Mechanics
• /
• pp.58.1-58.1
• /
• 2008

• Journal of Chest Surgery
• /
• 제12권3호
• /
• pp.174-182
• /
• 1979

This is a report on four cases of successful surgical correction of coarctation of the aorta [COA] in Department of the Thoracic & Cardiovascular Surgery, Hanyang University Hospital. The first case was a postductal type of coarctation of the aorta associated with Patent ductus arteriosus [PDA], Persistent left superior vena cava [LSVC] and richly developed collateral circulation. Blood pressure was measured to be hypertensive at the arm, but hypotensive at the legs. The coarctation of the aorta was corrected with following procedure: Partial resection of the aortic wall with diaphragmatic structure lust above and below the coarctating line of the aorta, and then the defect of the aortic wall was closed by lateral aortographic suture. PDA was closed by ligation procedure. The second case a preductal type of coarctation of the aorta associated with PDA, LSVC, ventricular septal defect [VSD] and poorly developed collateral circulation. Normal blood pressure was measured at the arm, but hypotension was observed at the legs. Correction of coarctation of the aorta was performed under the establishment of tube bypass because of poor collateral circulation. After resection of coarctating short segment, end to end anastomosis was performed without any tension. PDA was closed by division procedure. Simple suture closure of VSD was performed by open heart surgery two weeks after correction of COA. The third case was a long segment COA without any other anomaly. Blood pressure was measured to be hypertensive at the arm, but hypotensive at the legs. Vascular prosthesis was performed using Teflon graft tube after resecting coarctating long segment [6.5 cm] of the aorta. The fourth case was a long segment COA associated with aortic insufficiency and richly developed collateral circulation. Normal blood pressure was measured at the arm, but hypotension was observed at the legs. Vascular prosthesis was performed using Teflon graft tube after resecting coarctating long segment [6.0 cm] of the aorta. Both blood pressure and peripheral pulse on the arm and the legs returned to normal postoperatively in all patients.

• 한국태양에너지학회 논문집
• /
• 제27권4호
• /
• pp.167-173
• /
• 2007

This study analyzed by simulation using TRNSYS as well as by experiment on the solar district heating system installed for the first time for the district heating system in Bundang. Simulation analysis using TRNSYS focused on the thermal behavior and long-term thermal efficiency of solar system. Experiment carried out for the reliability of simulation system. This solar system where the circuits of two different collectors, flat plate and vacuum tube collector, are connected in series by a collector heat exchanger, and the collection characteristics of each circuit varies. Therefore, these differences must be considered for the system's control. This system uses variable flow rate control in order to obtain always setting temperature of hot water by solar system. Specifically, this is a system that heats returning district heating water (DHW) at approximately $60^{\circ}C$ using a solar collector without a storage tank, up to the setting temperature of approximately $85{\sim}95^{\circ}C$ To realize this, a flat plate collector and a vacuum tube collector are used as separate collector loops. The first heating is performed by a flat plate collector loop and the second by a vacuum tube collector loop. In a gross collector area basis, the mean system efficiency, for 4 years, of a flat plate collector is 33.4% and a vacuum tube collector is 41.2%. The yearly total collection energy is 2,342GJ and really collection energy per unit area ($m^2$) is 1.92GJ and 2.37GJ respectively for the flat plate vacuum tube collector. This result is very important on the share of each collector area in this type of solar district heating system.

• 콘크리트학회논문집
• /
• 제26권6호
• /
• pp.707-714
• /
• 2014

콘크리트 충전강관(CFT)은 강관의 내부에 콘크리트로 채워진 기둥이다. CFT는 강재와 콘크리트로 구성되며, 강재는 콘크리트를 내부에서 구속시켰고, 내부 콘크리트는 기둥의 압축하중을 감당한다. 본 실험에서 73~100MPa급 고강도 콘크리트에 관해 유동성실험, 압축강도실험, 압송압력실험을 실시하였으며, CFT용 고강도 콘크리트의 물리적 성질을 알아보기 위해 슬럼프, 슬럼프 플로우, 공기량, U-box시험, O-Lot시험, L-flow시험이 진행되었다. 이러한 연구의 결과를 바탕으로 Mock-up테스트에서 콘크리트 충전성 시험, 수화열 측정 시험, 응력계측 시험을 수행하였다. 현장적용은 상암동 및 서강대 현장의 두 곳에 각각 ${\Box}-566{\times}566{\times}10$, ${\Box}-400{\times}400{\times}25$의 대상기둥을 선정하여 현장계측을 진행하였다. CFT기둥의 장기거동 예측에 관하여 설계하중에 대해 콘크리트의 탄성변형과 건조수축, 크리프 수축을 고려한 ACI 209 재료모델을 사용한 결과는 계측결과와 거의 일치하였다.

• 한국농공학회논문집
• /
• 제55권6호
• /
• pp.155-165
• /
• 2013

Recently, geotextile tube method can be widely applied to the river, costal and marine in the construction field, such as embankment, groin, breakwater, dyke structures and so on, in advanced countries of the world. And that has been constructed at the temporary road for incheon, ilsan-bridge construction and coast erosion protection in republic of korea. Geotextile tube is a tube shaped geotextile product and hydraulic pumping filled with dredged soils. In this paper, the numerical analysis was performed to investigate the behavior of geotextile tube with various properties of material character, shape condition, construction pressure and so on. Also, the field test was conducted in order to identify the construction ability of Samangum waterproof embankment using geotextile tube. According to the applied of field test, geotextile tube was 65 m long and 4.0 m diameter. Also, the permeability coefficient and ultimate tensile strength of geotextile tube is $1.6{\times}10^{-1}$ cm/sec and 205.26 kN/m, respectively. As a result of filed test, when filled, geotextile tube does not attain the same as its unfilled theoretical diameter, but may reach approximately of 55 percent of the theoretical diameter. At the time, geotextile tubes were 12.56 m in circumference and filled to a height of about 2.2 m. This paper presents case study on field application and behavior analysis of the saemangum waterproof embankment donggin 1 division construction using geotextile tube.

• Korean Journal of Ophthalmology
• /
• 제32권6호
• /
• pp.438-444
• /
• 2018

Purpose: To compare the success rates of performing only silicone tube intubation versus carrying out both conjunctival resection and silicone tube intubation. Methods: The subjects of this study involved 62 patients (96 eyes) between October 2015 and May 2017 who were diagnosed as having punctal stricture or nasolacrimal duct stenosis. Out of 96 eyes, 47 underwent only silicone tube intubation, and 49 underwent both silicone tube intubation and conjunctival resection. Three parameters were measured at 1, 3, and 6 months after the surgery: the area of the tear meniscus using RTVue-100 anterior segment optical coherence tomography, the height of the tear meniscus using a slit lamp microscope, and the subjective satisfaction of patients as a result of improved sympotms like epiphora. The surgery was considered successful when the patients' experienced the resolution of symptoms and reduction of the area and height of the tear meniscus. Results: The area of the tear meniscus, height of the tear meniscus, and subjective satisfaction of patients was superior in the group that underwent both silicone tube intubation and conjunctival resection compared silicone tube intubation only. Based on these results, the success rate of the surgery was 68.9% in the group that underwent only silicone tube intubation and 78.7% in the group that underwent both silicone tube intubation and conjunctival resection. Conclusions: The resection of relaxed plica semilunares seems to increase the success rate of silicone tube intubation through the reduction of the area and height of the tear meniscus. Therefore, after determining the degree of conjunctivochalasis, if it was found to be severe, a combination with conjunctival resection was expected to increase the success rate of the surgery.