A Study on the Neumann-Kelvin Problem of the Wave Resistance (조파저항에서의 Neumann-Kelvin 문제에 대한 연구)
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- Journal of the Korean Society of Fisheries and Ocean Technology
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- v.21 no.2
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- pp.131-136
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- 1985
The calculation of the resulting fluid motion is an important problem of ship hydrodynamics. For a partially immersed body the condition of constant pressure at the free surface can be linearized. The resulting linear boundary-value problem for the velocity potential is the Neumann-Kelvin problem. The two-dimensional Neumann-Kelvin problem is studied for the half-immersed circular cylinder by Ursell. Maruo introduced a slender body approach to simplify the Neumann-Kelvin problem in such a way that the integral equation which determines the singularity distribution over the hull surface can be solved by a marching procedure of step by step integration starting at bow. In the present pater for the two-dimensional Neumann-Kelvin problem, it has been suggested that any solution of the problem must have singularities in the corners between the body surface and free surface. There can be infinitely many solutions depending on the singularities in the coroners.
Background : Cervical tuberculous lymphadenitis(CTL) is one of the most common extra-pulmonary tuberculosis. Recently overall incidence of pulmonary tuberculosis has decreased, but the incidence of tuberculous lymphadenitis has not decreased. Its duration of treatment is still controversial and the pathogenesis, prognosis and relationship with other site tuberculous are poorly published. So we did a retrograde study of 120 cases of confirmed CTL about its clinical manifestations. Method : All patients were applied fine needle aspiration(FNA) of palpable enlarged cervical lymph nodes and 114 patients were examined for AFB smear and 34 patients for TB culture with aspirated fluid. 57 patients were examined Mantoux test(5TU with PPD-S). With above methods, a total of 120 patients was diagnosed as having CTL. Results : 1) CTL is most prevalent in young women between the age of 20~30 years and the incidence of CTL in female is 2.5 times higher than that of male. It is located most commonly in the posterior cervical area. The most common presenting symptom is painless palpable enlarged cervical lymph nodes. 2) With FNA of enlarged cervical lymph nodes, the percentage of histopathological positivity is 82.3%. The percentage of AFB smear positivity is 38.6%, and that of TB culture positivity is 17.6%(p<0.001). 3) Pulmonary tuberculosis is noted in 79 cases(65.8%). And 42 cases(53.5%) of them had minimal pulmonary tuberculosis. In 14 cases(11.7%), other extrapulmonary tuberculosis coexsisted and pleural tuberculosis was most Common in the order. 4) CTL was treated with anti-tuberculous medication(first line drug) and median treatment duration was 18.5months. During treatment, the size of involved lymph nodes decreased gradually in 62 cases(75.8%), newly developed lymph nodes were found in 25 cases(30.4%), fluctuation formation in 22 cases(26.8%) and fistula formation in 14 cases(17.0%). Conclusion : CTL is prevalent in women between the age of 20~40 years and it involves posterior cervical area most commonly. CTL is treated with long-term anti-tuberculous chemotherapy. We think it is one manifestation of systemic disease and frequently coexisting with pulmonary tuberculosis. Despite anti-tuberculous chemotherapy, the size of involved lymph nodes was increased, new lymph nodes were developed or fluctuation and fistula formed in involved lymph nodes. After sufficient medication, when the patient felt pressure discomfort from enlarged lymph node or fistula was formed, we recommended total excision of involved lymph nodes.
The detection methods are required to monitor and diagnose the abnormality on the insulation condition inside a gas-insulated switchgear (GIS). Due to a good sensitivity to the products decomposed by partial discharges (PDs) in
The geological CO2 sequestration in underground geological formation such as deep saline aquifers and depleted hydrocarbon reservoirs is one of the most promising options for reducing the atmospheric CO2 emissions. The process in geological CO2 sequestration involves injection of supercritical CO2 (scCO2) into porous media saturated with pore water and initiates CO2 flooding with immiscible displacement. The CO2 migration and distribution, and, consequently, the displacement efficiency is governed by the interaction of fluids. Especially, the viscous force and capillary force are controlled by geological formation conditions and injection conditions. This study aimed to estimate the effects of surfactant on interfacial tension between the immiscible fluids, scCO2 and porewater, under high pressure and high temperature conditions by using a pair of proxy fluids under standard conditions through pendant drop method. It also aimed to observe migration and distribution patterns of the immiscible fluids and estimate the effects of surfactant concentrations on the displacement efficiency of scCO2. Micromodel experiments were conducted by applying n-hexane and deionized water as proxy fluids for scCO2 and porewater. In order to quantitatively analyze the immiscible displacement phenomena by n-hexane injection in pore network, the images of migration and distribution pattern of the two fluids are acquired through a imaging system. The experimental results revealed that the addition of surfactants sharply reduces the interfacial tension between hexane and deionized water at low concentrations and approaches a constant value as the concentration increases. Also it was found that, by directly affecting the flow path of the flooding fluid at the pore scale in the porous medium, the surfactant showed the identical effect on the displacement efficiency of n-hexane at equilibrium state. The experimental observation results could provide important fundamental information on immiscible displacement of fluids in porous media and suggest the potential to improve the displacement efficiency of scCO2 by using surfactants.
The Komdok Pb-Zn deposit, which is the largest Pb-Zn deposit in Korea, is located at the Hyesan-Riwon metallogenic zone in Jiao Liao Ji belt included Paleoproterozoic Macheolryeong group. The geology of this deposit consists of Paleoproterozoic metasedimentary rocks, Jurassic Mantapsan intrusive rocks and Cenozoic basalt. The Komdok deposit which is a SEDEX type deposit occurs as layer ore and vein ore in the Paleoproterozoic metasedimentary rocks. Based on mineral petrography and paragenesis, dolomites from this deposit are classified four types (1. dolomite (D0) as hostrock, 2. early dolomite (D1) associated with tremolite, actinolite, diopside, sphalerite and galena from amphibolite facies, 3. late dolomite (D2) associated with talc, calcite, quartz, sphalerite and galena from amphibolite facies, 4. dolomite (D3) associated with white mica, chlorite, sphalerite and galena from quartz vein). The structural formulars of dolomites are determined to be Ca1.00-1.20Mg0.80-0.99Fe0.00-0.01Zn0.00-0.02(CO3)2(D0), Ca1.00-1.02M0.97-0.99Fe0.00-0.01Zn0.00-0.02(CO3)2(D1), Ca0.99-1.03Mg0.93-0.98Fe0.01-0.05Mn0.00-0.01As0.00-0.01(CO3)2(D2) and Ca0.95-1.04Mg0.59-0.68Fe0.30-0.36Mn0.00-0.01 (CO3)2(D3), respectively. It means that dolomites from Komdok deposit have higher content of trace elements (FeO, MnO, HfO2, ZnO, PbO, Sb2O5 and As2O5) compared to the theoretical composition of dolomite. These trace elements (FeO, MnO, ZnO, Sb2O5 and As2O5) show increase and decrease trend according to paragenetic sequence, but HfO2 and PbO elements no show increase and decrease trend according to paragenetic sequence. Dolomites correspond to Ferroan dolomite (D0, D1 and D2), and Ferroan dolomite and ankerite (D3), respectively. Therefore, 1) dolomite (D0) as hostrock was formed by subsequent diagenesis after sedimentation of Paleoproterozoic (2012~1700 Ma) silica-bearing dolomite in the marine evaporative environment. 2) Early dolomite (D1) was formed by hydrothermal metasomatism origined metamorphism (amphibolite facies) associated with intrusion (1890~1680 Ma) of Paleoproterozoic Riwon complex. 3) Late dolomte (D2) was formed from residual fluid by a decrease of temperature and pressure. and dolomite (D3) in quartz vein was formed by intrusion (213~181 Ma) of Jurassic Mantapsan intrusive rocks.
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70
As far as an opening device of fishing gears is concerned, applications of a kite are under development around the world. The typical examples are found in the opening device of the stow net on anchor and the buoyancy material of the trawl. While the stow net on anchor has proved its capability for the past 20 years, the trawl has not been wildly used since it has been first introduced for the commercial use only without sufficient studies and thus has revealed many drawbacks. Therefore, the fundamental hydrodynamics of the kite itself need to ne studied further. Models of plate and canvas kite were deployed in the circulating water tank for the mechanical test. For this situation lift and drag tests were performed considering a change in the shape of objects, which resulted in a different aspect ratio of rectangle and trapezoid. The results obtained from the above approaches are summarized as follows, where aspect ratio, attack angle, lift coefficient and maximum lift coefficient are denoted as A, B,