• 한국유체기계학회 논문집
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• 제12권5호
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• pp.47-53
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• 2009

A rotordynamic and detailed stability analysis in accordance with API 617 standard were performed with a turbo-compressor, which is one of key rotating machinery in refinery, petroleum, and power plants. The system is composed of rotor shaft, impeller, sleeve hub, balance drum, and coupling hub. The rotor system is supported by tilting pad bearings, which has 5 pads and pad on loading condition. The rotordynamic analysis specified by API 617 includes the critical speed map, mode shape analysis, Campbell diagram, unbalance response analysis, and stability analysis. In particular, the specifications of stability analysis consist of a Level 1 analysis that approximates the destabilizing effects of the labyrinth seals and aerodynamic excitations, and Level 2 analysis that includes a detailed labyrinth seal aerodynamic analysis. The results of a rotordynamic analysis and stability analysis can evaluate the operating compressor health and can be utilized as a guide of its maintenance, repair and trouble solution.

• Childhood Kidney Diseases
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• 제6권2호
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• pp.251-258
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• 2002

저자들은 다장기 부전과 패혈증에 의한 ?상태의 급성 신부전 환아 세 명에서 펌프를 이용한 CVVH를 이용하여 효과적으로 한외여과액을 유지할 수 있었던 경험을 문헌 고찰과 함께 보고하는 바이다.

• 대한한의학원전학회지
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• 제23권1호
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• pp.1-10
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• 2010

Wi Syndrome(痿證) mainly occurs from fluid damages[津液損傷] caused by heat in Gi(氣) phase of the Five viscera, while it sometimes come from the outside. Although the symptoms are presented in the limbs, the disorder roots in the Five viscera, most deeply located in the human body, Therefore, to approach the disorder, we must apply differentiation of the Five viscera in diagnosis. The Lungs, as the head of the Five viscera control the production and distribution of bodily fluids in the body. Functional disorder of the Lungs bring about Wi Syndrome regardless of it being in the Gi phase. Also, psychological depression leads to Wi Syndrome, In other words, depression and uneasiness easily results in the state of Gi blocking and fluid exhaustion in this modern society where there is less manual labor and excessive use of the brain. Besides Gi blockage, the top muscle[宗筋] theory is another important mechanism in the occurrence of Wi Syndrome. Moreover, the disorder is related to Yangmyeong(陽明), which is the sea of food, Chungmaek(衝脈) which is the sea of meridian, in addition to Immaek(任脈), Dokmeak (督脈) and Deameak(帶脈) which are all involved in Wi Syndrome. In conclusion, the Wi Syndrome happens when various factors involved lose balance and harmony with each other.

• Journal of Korean Neurosurgical Society
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• 제54권5호
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• pp.437-440
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• 2013

The cerebrospinal fluid tap test (CSFTT) is recommended as a key step in the diagnosis of idiopathic normal pressure hydrocephalus (iNPH). While there is no generally accepted evaluation period for ascertaining a CSFTT responder, a substantial number of patients are evaluated only once within 24 hours of the test for improvement in gait. We report an iNPH patient with a favorable response to shunt surgery, who was first judged a non-responder by this standard, though subsequently was judged a responder in virtue of repetitively testing gait over 7 days. A 68-year-old man presented with progressive impairment of gait, balance, and memory. He was diagnosed as iNPH with an Evans' ratio of 0.35. At first hospitalization, change in gait was evaluated 24 hours after the CSFTT. He didn't show any significant improvement and was judged as a non-responder. However, at the second CSFTT, we repetitively tested his change in gait over seven days. Forty-eight hours after the tap, he showed significant improvement in his gait. He was then confirmed as a responder. After the operation, the gait difficulties were almost fully resolved. Further studies developing the standard procedure of the CSFTT should be considered.

• 대한물리치료과학회지
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• 제5권4호
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• pp.729-750
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• 1998

The purpose of this Review is to help activities of daily living by normalizing bodily functions through the use of negative pressure. Cupping therapy has been holding the important role as a form of treatment in ancient medicine of Oriental and Occidental country, and still being used widely due to it's effectiveness. Principle of Cupping therapy is to neutralize somatic dysfunctions by elimination of nonphysiological somatic fluid of hematoma through application of negative pressure on region of dermatomal meridian. The effectiveness of Cupping therapy as follows; 1) Effects on acid base balance of bodily fluid. 2) Through the reabsorption of subcutaneous hematoma, it affects on formation of immune system and produce the blood serum cleaning reaction. 3) By application of negative pressure on subcutaneous, induce renal system to produce steroid hormone. 4) By stimulating hemopoietic system, it maxmize the blood production level. Recently, Alternative medicine has been a focus due to it's nature of effectiveness and safety without adverse complication. Therefore, every family possess and use the cupping modality for preventive measure and/or treatment purpose in order to eliminate accumulated byproducts of body and clean the blood system.

• Korea-Australia Rheology Journal
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• 제14권2호
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• pp.49-55
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• 2002

To understand the large amplitude oscillatory shear (LAOS) behavior of complex fluids, we have investigated the flow behavior of a network model in the LAOS environment. We applied the LAOS flow to the model proposed by Vaccaro and Marrucci (2000), which was originally developed to describe the system of associating telechelic polymers. The model was found to predict at least three different types of LAOS behavior; strain thinning (G' and G" decreasing), strong strain overshoot (G' and G" increasing followed by decreasing), and weak strain overshoot (G' decreasing, G" increasing followed by decreasing). The overshoot behavior in the strain sweep test, which il often observed in some complex fluid systems with little explanation, could be explained in terms of the model parameters, or in terms of the overall balance between the creation and loss rates of the network junctions, which are continually created and destroyed due to thermal and flow energy. This model does not predict strain hardening behavior because of the finitely extensible nonlinear elastic (FENE) type nonlinear effect of loss rate. However, the model predicts the LAOS behavior of most of the complex fluids observed in the experiments.he experiments.

• 한국소음진동공학회논문집
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• 제15권2호
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• pp.148-155
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• 2005

As functional requirement of massive digital information storage devices are on a trend for the higher data transfer rate and lower cost, many different technical efforts are being tested and implemented in the industry. FDB(fluid dynamic bearing) is one of the major breakthroughs in rotor design in terms of TMR(track misregistration) budget. Although FDB analysis based on Reynolds' equation is well established and popularly being used for FDB design especially for the estimation of bearing stiffness, there are obvious limitations in the approach due to the inherent assumptions. A generalized analysis tool employing the full Navier-Stokes equation and the energy balance is to be beneficial for detailed FDB design. In this publication, an efficient geometry modeling method is presented that provides fully integrated inputs for general FVM/FDM(finite volume method/ finite difference method) codes. By virtue of the flexibility of the presented method, many different detailed FDB design and analysis are carried over with ease.

• 대한조선학회논문집
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• 제48권4호
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• pp.308-316
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• 2011

Although a yacht sails operate with large displacement due to very thin thickness, many studies for flow around yacht sails have not considered the sail deformation. The sail deformation not only caused a change in the center of effect(CE) on the sail but also a change in the thrust of the sail. The change of the CE and thrust affects the center of lateral resistance(CLR) and side forces of the hull, and the balance of the yacht. These changes affect the motion of the yacht which changes the velocity of the yacht. Thus, when analyzing the flow around yacht sails, the sail deformation should be considered. In the present study, fluid-structure-interaction(FSI) analysis of a two dimensional section of yacht sails was performed to consider the effects of sail deformation on the lift and drag performance. FSI and moving mesh methods were studied. Computational methods were verified using benchmark test cases such as the flow around horizontal and vertical cantilever beams. Shape deformation, pressure distribution, lift forces and separation flow were compared for both rigid and deformable sail.

• 한국유체기계학회 논문집
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• 제12권6호
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• pp.41-46
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• 2009

This paper deals with the operating-speed (high-speed) balancing of a refinery gasoline HDS (hydrodesulfurization) process recycle-gas 8-stages compressor rotor. A low-speed balancing condition of the rotor was measured as maintaining the G2.5 level. But an inspection run of operating-speed balancing condition, using tilting-pad journal bearings of actual use, showed that while it could be continuously-operated safely at a rated speed of 10,500 rpm, the rotor would not be able to run over 11,000 rpm as the vibration increased very sharply, approaching 11,000 rpm. In order to cure that a series of operating-speed balancing, which first calculated balance correction-weights by applying the influence coefficient measured and calculated at 10,500 rpm and then implemented correction works, was carried-out. The final operating-speed balancing results showed that the vibrations at the bearing pedestals represented very good levels of 0.2 mm/s by decreasing to as much as the 1/10 of the original vibrations and particularly, even at a targeted maximum continuous operating speed, MCS, of 11,500 rpm the vibrations represented about 1 mm/s, which is the operating-speed balancing vibration specification of API. Therefore, the expansion of MCS was successfully accomplished through the operating-speed balancing.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2173-2187
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• 2022

A 3D thermo-elasto-hydrodynamic model is developed to analyze the sealing performance of a notched mechanical seal applied in the reactor coolant pump. In the model, the generalized Reynolds equation, the energy equation coupled with notch heat balance equation, the heat conduction equations, and the deformation equations of the sealing rings are iteratively solved by the finite element method. The film pressure and temperature distribution are obtained, and the deformation of the sealing rings is revealed to study the mechanism of the notched mechanical seals. A parameterized study is conducted to analyze the sealing performance under different operating conditions. As a comparison, the sealing performance of non-notched seals is also studied. The results show that the hydrostatic effect is dominant in the load-carrying capacity of the fluid film due to the radial mechanical and thermal deformations. The notch can cool the fluid film and influence the thermal deformation of seal rings. The sealing performance is sensitive to the pressure difference, ambient temperature, and rotational speed. It is suggested to set the notches on the softer sealing rings to acquire the greater hydrodynamic effect. Compared with the non-notched, the notched end face holds a better lubrication performance, especially under lower rotational speed.