• 비파괴검사학회지
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• 제21권5호
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• pp.526-531
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• 2001

공통축 형태로 배치된 비자성체 이중관에 있어서 유한요소해석 상용 소프트웨어와 실험적인 방법을 각각 이용하여 원격장 와전류 에너지의 전달 경로를 연구하였다. 연구결과 이중관에 있어서 원격장 와전류 에너지는 두 관 사이의 공간을 따라 흐르는 것이 아니라, 단일 튜브의 경우와 마찬가지로 외측 튜브의 외면을 따라 흐름을 확인하였다. 이는 원격장 와전류 효과의 관벽투과 특성이 이중관에 있어서도 유효함을 보여주는 것이다. 따라서, 중수로형 핵연료 채널과 같은 이중관 형태를 대상으로 내관 및 외관의 내 외부 결함 탐상, gap 분포 및 지지대의 위치 확인 등에 원격장 와전류 방법의 관벽투과 특성이 응용될 수 있음을 보였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.269-274
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• 2011

A CFD analysis was performed to examine the inner channel blockage of dual-cooled fuel which has being developed for the power uprate of a pressurized water reactor (PWR). The dual-cooled fuel consists of an annular fuel pellet($UO_2$) and dual claddings as well as internal and external cooling channels. The dual-cooled annular fuel is different from a conventional solid 려el by employing an internal cooling channel for each fuel pellet as well as an external cooling channel. One of the key issues is the hypothetical event of inner channel blockage because the inner channel is an isolated flow channel without the coolant mixing between the neighboring flow channels. The inner channel blockage could cause the Departure from Nucleate Boiling (DNB) in the inner channel that eventually causes a fuel failure. This paper presents the CFD simulation of the flow through the side holes of the bottom end plug for the complete entrance blockage of the inner channel. Since the amount of coolant supply to the inner channel depends on largely the pressure loss at the side hole, the pressure loss coefficient of the side hole was estimated by the CFD analysis. The CFD prediction of the loss coefficient showed a reasonable agreement with an experimental data for the complete blockage of both the inner channel entrance and the outer channel. The CFD predictions also showed the decrease of the loss coefficient as the outer channel blockage increases.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.382-386
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• 2011

In this study, a CFD code is developed to perform simulation of the surface and internal flow of a three-dimensional rectangular cavity driven by an external gas flow. Investigated in this study are surface characteristic such as surface tension, surface dilational viscosity(or surface elasticity), and surface viscosity. Visualization of the surface of water is performed to compare with the numerical results obtained with the developed in-house code. We have found that the surface flow is very sensitive to the surface tension and other configurations. The surface flow velocity obtained from the numerical solution is lower than the experimental result.

• 한국수소및신에너지학회논문집
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• 제31권1호
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• pp.73-81
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• 2020

For the fault tree analysis (FTA) analysis of the packaged hydrogen filling station, the composition of the charging station was analyzed and the fault tree (FT) diagram was prepared. FT diagrams were created by dividing the causes of events into external factors and internal factors with the hydrogen event as the top event. The external factors include the effects of major disasters caused by natural disasters and external factors as OR gates. Internal factors are divided into tube tailer, compressor & storage tank, and dispenser, which are composed of mistakes in operation process and causes of accidents caused by parts leakage. In this study, the purpose was to improve the hydrogen station. The subjects of this study were domestic packaged hydrogen stations and FTA study was conducted based on the previous studies, failure mode & effect analysis (FMEA) and hazard & operability study (HAZOP). Top event as a hydrogen leaking event and constructed the flow of events based on the previous study. Refer to "Off shore and onshore reliability data 6th edition", "European Industry Reliability Data Bank", technique for human error rate prediction (THERP) for reliability data. We hope that this study will help to improve the safety and activation of the hydrogen station.

• Steel and Composite Structures
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• 제10권3호
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• pp.261-279
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• 2010

Generally, a box tube, which is used for an existing square CFT structure, is made by welding four plates. The manufacturing efficiency of this steel tube is poor, and it also needs special welding technology to weld its internal diaphragm and the through diaphragm. Therefore, an interior-anchor-type square steel tube was developed using the method of cold-forming thin plates to prevent welding of the stress concentration position, and to maximize the section efficiency. And, considering of the flow of beam flange load, the efficiency of erection and the weldability of the diaphragm to thin walled steel column, the external diaphragm connection was selected as the suitable type for the welded built-up square CFT column to beam connection. And, an analytical study and tests were conducted to evaluate the structural performance of the suggested connection details and to verify the suggested equations for the connection details. Through this study, the composite effect of the internal anchor to concrete, the resistance and stress distribution of the connections before and after the existing column is welded to the beam, the effective location of welding in connection were analyzed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1120-1125
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• 2007

Experimental study on the control of randomly disturbing system is conducted. External and internal disturbances are imposed to the system in combined manner. A vertical propeller system exposed horizontal weak turbulent air flow is chosen as an experimental model. The aim of the control system is to maintain the angular position of vertical propeller in parallel to air flow. Trajectory Tracking Stochastic Controller (TTSC) is designed to ensure system's stability while following system command. The Trajectory Tracking Stochastic Controller is composed of two controller, one is stochastic controller to suppress internal random noise and the other one is trajectory-tracking controller to follow the command having random noise. The proposed hybrid controller, TTSC, shows remarkable performance in pitch control of vertical propeller system in wind-tunnel test

• 한방안이비인후피부과학회지
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• 제29권4호
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• pp.114-130
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• 2016

Objectives : This study is performed to investigate the therapy on tinnitus through the literature of Eastern and Western medicine. Methods : This study review the definition, etiology, classification, internal and external methods of treatment of tinnitus based on 50 articles of Eastern medicine, 16 articles of Western medicine about the treatment of tinnitus. Results : The results were as follows. 1. In Eastern medicine, the cause and mechanism of disease of tinnitus arose from the state of qi-blood deficiency, internal dampness-heat and depression stagnation. In Western medicine, there are mainly caused by damage to the auditory system the lower induced changes in the upper. 2. In Eastern medicine, differentiation of syndromes classifies clinical aspects, and cause and mechanism of disease. In Western medicine, it divides into an generating region, clinical and associated symptoms aspects. 3. In Eastern medicine, internal method of treatments of tinnitus are divided into four treatments. In Western medicine, internal methods of tinnitus are vasodilators, blood-flow improvers, Metabolism improvers etc. 4. In Eastern medicine, external method of treatments of tinnitus are paste preparation method, powder preparation method, pill preparation method, acupuncture & moxibustion method. In Western medicine, external method of treatments of Tinnitus are divided into injection, other surgical therapies and adjuvant therapy. Conclusions : Until now, there is no perfect, effective single treatment. We think that Eastern medicine approach and treatment can be helpful to overcome the limitations of tinnitus cure.

• 설비공학논문집
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• 제14권4호
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• pp.315-323
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• 2002

The commercial viability of heat exchanger is mainly dependent on their long-term fouling characteristics because the fouling increases the pressure loss and degrades the thermal performance of a heat exchanger. An experimental study was performed to investigate the characteristics of fluid flow and heat transfer in a fluidized bed heat exchanger with circulating various solid particles. The present work showed that the drag force coefficients of particles in the internal flow were higher than those in the external flow, in addition, the solid particle periodically hitting the tube wall broke the thermal boundary layer, and increased the rate of heat transfer. Particularly when the flow velocity was low, the effect was more pronounced.

• Journal of Chest Surgery
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• 제37권10호
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• pp.839-844
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• 2004

배경 및 목적: 속가슴동맥 편과 유리 노동맥 편의 Y-복합이식편은 관상동맥우회 술에 많이 이용된다. 이 연구의 목적은 속가슴동맥 편의 혈류를 증가시킬 수 있는 방법을 찾고 Y-복합이식편의 혈류역학을 알고자 함이다. 대상 및 방법: 관상동맥우회 술을 받은 15예에서 속가슴동맥 편을 두 가지 방법으로 처치하여 속가슴동맥 혈류량을 측정하였다. 7예에서는 혈관 외부에만 파파베린 액을 처치하였고 8예에서는 혈관 내로 파파베린 액을 주입하였다. 다른 18예에서는 속가슴동맥 편과 유리 노동맥 편으로 Y-복합이식편을 만들어 사용하였고 그 자유 혈류량과 두 분지의 혈류 변화를 조사하였다. 결과: 속가슴동맥 편의 혈관 내로 파파베린을 주사한 경우는 혈관외부에 파파베린을 처치한 경우보다 약 2배의 자유혈류량을 얻을 수 있었다(47.7$\pm$9.6 mL/min와 100.8$\pm$26.3 mL/min, p<0.001). Y-복합이식편의 양측을 다 연 상태에서 총 자유혈류량은 속가슴동맥 측만을 열었을 때나 노동맥 측만을 열었을 경우보다 훨씬 많았다(173.3$\pm$45.3 mL/min와 121.1$\pm$34.3 mL/min 혹은 117.5$\pm$42.8 mL/min, 각각 p<0.001). Y-복합이식편의 양 분지를 다 연 경우 양측의 혈류량은 차이가 없었다(85.4$\pm$27.8 mL/min와 87.9$\pm$42.4 mL/min, p=0.772). Y-복합이식편에서 한 측의 혈류량은 다른 측을 열 때보다 막을 때 훨씬 많았다. 결론: 속가슴동맥 편의 혈관 내에 파파베린 액을 주입하는 방법은 자유혈류량을 올릴 수 있는 매우 효과적인 방법이다. 속가슴동맥 편과 유리 노동맥 편의 Y-복합이식편은 속가슴동맥의 단독이식편보다 더 많은 자유혈류량을 보이며, Y-복합이식편의 한 측의 혈류량은 다른 측의 혈류량의 변화에 따라 변할 수 있다.

• 수산해양기술연구
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• 제56권2호
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• pp.83-93
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• 2020

In fisheries, the importance of designing efficient fish cages is being emphasized as aquaculture has become more production than capture fishing. Particularly, the gravity cage system is one of the popular fish cage system in Korea. Currently, gravity cages of various shapes and sizes are being widely designed and installed in offshore and inland seas. The cage is subject to external forces, such as currents and waves, and the shape of the structure and tension on the ropes changes according to these external forces. Thus, it is important to accurately calculate these dynamic behavior, including the external forces and tension on the structure during the design stage. In this study, three types of cage systems with an equal internal volume of 8000 ㎥ were analyzed using mass-spring models and their behavior was interpreted through simulations. These simulations were used to analyze the behavior and tension of the ropes in response to currents and waves to aid in the selection of individual cage sizes for a given total volume. The numerical calculation results indicate that depending on the flow rate, the most resistant system is System 1, which has eight strays, and System 2 and System 3 have 69.4% and 54.8% of the resistance of System 1. Further, total resistance increased as the number of cages increased for all flow rates.