• 한국해양공학회지
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• 제23권4호
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• pp.69-77
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• 2009

Structural analysis of a brake shoe for commercial vehicle was performed using finite element method. Since the strength of a brake shoe is affected by the magnitude and distribution shape of the contact pressure with the drum, the contact pressure between the shoe friction material and drum was calculated using a 2-Dimensional non-linear contact analysis in a state. And the brake was actuated by input air pressure and the drum of it was calculated both stationary and dynamic based on forced torque applied to the drum during the static state analysis. The results of the above analysis were then used as the load boundary conditions for a 3-Dimensional shoe model analysis to determine the maximum strain on the shoes. In the analysis model, the values of tensile test were used for the material properties of the brake shoes and drum, while the values of compression test were used for the friction material. We assumed it as linear variation, even though the properties of friction material were actually non-linear. The experiments were carried out under the same analysis conditions used for fatigue test and under the same brake system which equipped with a brake drum based on the actual axle state in a vehicle. The strains were measured at the same locations where the analysis was performed on the shoes. The obtained results of the experiment matched well with those from the analysis. Consequently, the model used in this study was able to determine the stress at the maximum air pressure at the braking system, thereby a modified shoe model in facilitating was satisfied with the required endurance strength in the vehicle.

• The Journal of Korean Physical Therapy
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• 제12권1호
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• pp.101-112
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• 2000

The aim of this study is to compared the cerebral palsy children with normal children in the exercise and cardio vascular ability after this study as the fundamental data fer mating programs for the cerebral palsy children. The test of this study is about twenty girls, the control group of the normal children(n=10) and the experiment group of cerebral palsy children(n=10). They were studied in four aspects which were the anthropometry, the medical check in the rest, the physical fitness or exercise roads test and the change of the target heart rate during exercise. The result were as follows : 1. The characteristic of the physical type : The control group is higher than the experiment group in the standing height and the body weight but their's little difference between them (p<0.05). The control group is lower than the experiment group in the body fat. 2. The characteristic of the medical check in the rest : The control group is higher than the experiment group in the vital capacity and flood expiratoryvolume one second. The control group is higher that the experiment group in the blood pressure of systolic and Diastolic. There's little difference between them(p<0.01). The control is lower than the experiment group in the heart pulse rate. There's little difference between them(p<0.005). 3. The characteristic of basic physical strength evaluation : The experiment group is the lowest dynamic muscular endurance, balance, agility and endurance which need to move the body with weight. The control group is much higher than the experiment group in the flexibility and muscle strength(Back strength). There's no difference between them(p<0.05). 4. The characteristics of the exercise stress last : The control group is higher than the experiment group in the endurance, the maximum of oxygen intake, endurance level and the out take of calory. There's little difference between them(p<0.01). 5. The characteristic of the change of the target heart rate during exercise : The control group is lower than the experiment group exchange of target heart rate, There's no difference them.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.419-424
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• 2002

The HANARO, a multi-purpose research reactor of 30 MWth open-tank-in-pool type, has been under normal operation since its initial criticality In February, 1995. Many experiments should be safely performed to activate the utilization of the HANARO. A flow simulation facility is being developed for the endurance test of reactivity control units for extended life times and the verification of structural integrity of those experimental facilities prior to loading in the HANARO. This test facility is composed of three major parts; a half-core structure assembly, flow circulation system and support system. The flow circulation system is composed of a circulation pump, a core flow pipe, a core bypass flow pipe and instruments. The system is to be filled with de-mineralized water and the flow should be met the design flow to simulate similar flow characteristics in the core channel of the half-core test facility to the HANARO. This paper, therefore, describes an analytical analysis to study the flow behavior of the system. The computational flow analysis has been performed for the verification of system pressure variation through the three-dimensional analysis program with standard k-$\epsilon$ turbulence model and for the verification of the structural piping integrity through the finite element method. The results of the analysis are satisfied the design requirements and structural piping integrity of flow circulation system.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2001년도 정기학술대회
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• pp.337-337
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• 2001

High voltage ceramic capacitors are widely applied in power electronic circuits, such as filters, snubbers, and resonant circuits, due to their excellent features of high voltage endurance and low aging. This paper presents a result of failure analysis and reliability evaluation for high voltage ceramic capacitors. The failure nodes and failure mechanisms were identified in order to understand the failure physics in a component. The causes of failure mechanisms for zero resistance phenomena under withstanding voltage test in high voltage ceramic capacitors molded by epoxy resin were studied by establishing an effective closed-loop failure analysis. Also, the condition for dielectric breakdown was investigated. Particular emphasis was placed on breakdown phenomena at the ceramic-epoxy interface. The validity of the results in this study was confirmed by the results of accelerated testing. Thermal shock test as well as pressure cooker test for high voltage ceramic capacitor mounted on a magnetron were implemented. Delamination between ceramic and epoxy, which, might cause electrical short in underlying circuitry, can occur during curing or thermal cycling. The results can be conveniently used to quickly identify defective lots, determine mean time to failure (MTTF) of each lot at the level of Inspection, and detect major changes in the vendors processes.

• 대한기계학회논문집A
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• 제31권10호
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• pp.1046-1052
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• 2007

Elastic-plastic structural analysis for regenerative cooling chamber of gas generator was performed. Uniaxial tension test was conducted for STS316L at room and high temperature conditions to get the material data necessary for the structural analysis of the chamber which was operated under thermal load and high internal pressure. Physical properties including thermal conductivity, specific heat and thermal expansion were also measured. The structural analysis for four different types of regenerative cooling chamber of gas generator revealed that increased cooling performance decreased the thermal load and strain of the cooling channel structure. The results propose that in order for the regenerative cooling gas generator chamber to have high structural stability with endurance to high mechanical and thermal loads, it is important for the chamber to be designed to have high cooling performance.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.802-807
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• 2007

Elastic-plastic structural analysis for regenerative cooling chamber of gas generator was performed. Uniaxial tension test was also conducted for STS316L at room and high temperature conditions to get the material data necessary for the structural analysis of the chamber which is operated under thermal load and high internal pressure. Physical properties including thermal conductivity, specific heat and thermal expansion data were also measured. The structural analysis for four different types of regenerative cooling chamber of gas generator revealed that increased cooling performance decreases the thermal load and strain of the cooling channel. The results propose that in order for the regenerative cooling gas generator chamber to have high structural stability with endurance to high mechanical and thermal loads, it is important for the chamber to be designed to have high cooling performance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.557-560
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• 2004

This paper is to investigate the fire endurance of high performance concrete with the contents of cellulose fiber. According to test results, the use of CL lead to decrease in fluidity. For compressive strength, the use of CL had no influence on compressive strength. For spalling properties, plain concrete showed a severe spalling failure. The use of CL protected from spalling of concrete, but most specimens had scale failure and partial destruction of specimens. This is due to the insufficient fiber length and diameter of CL fiber, which was unable to discharging the internal vapour pressure. For this reason, CL fiber can not be used to protect from spalling oh high performance concrete. Residual strength was observed to $5\~7\%$ of original strength.

• The Korean Journal of Physiology
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• 제7권1호
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• pp.13-21
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• 1973

An attempt was made to study circulatory and respiratory responses to the passive tilt. Anesthetized dogs were tilted from horizontal to upright $(+90^{\circ})$ and head down $(-90^{\circ})$ position. The arterial blood pressure was decreased in the upright position and was decreased slightly in the head down position comparing to that in the horizontal position. Cardiac index also decreased in the both upright and head down positions. The total systemic vascular resistance was slightly increased in the upright position and was markedly increased in the head down position. The mean pulmonary arterial pressure was significantly decreased in the both upright and head down positions. The total pulmonary vascular resistance was decreased in the both upright and head down positions. Oxygen consumption was slightly decreased in the upright position, whereas it was slightly increased in the head down position. The A-V $O_2$ difference (vol. %) was slightly increased in the upright position and increased in the head down position. From the above results, process of the circulatory compensation to the gravity in the Passive tilting test was discussed. Neuronal cardiovascular regulation to the gravity and tile adaptation of capacitance vessles to hydrostatic stress and oxygen consumption concerning anoxic endurance of the brain were also discussed.

• 한국전문물리치료학회지
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• 제25권3호
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• pp.60-67
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• 2018

Background: Progressive muscle weakness is aggravated not only in the skeletal muscles but also in the respiratory muscles in many patients with neuromuscular diseases (NMD). Inspiratory muscle training (IMT) has been reported as therapy for pulmonary rehabilitation to improve respiratory strength, endurance, exercise capacity, and quality of life, and to reduce dyspnea. Objects: The purpose of this study was to determine the effect of playing harmonica for 5 months on pulmonary function by assessing the force vital capacity (FVC), peak cough flow (PCF), maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and maximal voluntary ventilation (MVV) in patients with NMD. Methods: Six subjects with NMD participated in this study. The subjects played harmonica once a week for 2 hours at a harmonica academy and twice a week for 1 hour at home. Thus, training was performed thrice a week for 23 weeks. The examiner assessed pulmonary function by measuring FVC in the sitting and supine positions and PCF, MIP, MEP, and MVV in the sitting position at the beginning of training and once a month for 5 months. Results: Both sitting and supine FVC significantly increased after playing harmonica (p=.042), as did MIP (p=.043) and MEP (p=.042). Conclusion: Playing harmonica can be used as an effective method to improve pulmonary function in patients with NMD.

• 한국정밀공학회지
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• 제20권3호
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• pp.149-156
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• 2003

The estimation of fatigue limit for the component with complicated shape is difficult than of standard fatigue specimen, due to complex test equipment. So, we substitute maximum principle stress from FEM results for fatigue limit diagram made by standard fatigue specimen. Then we can estimate endurance safety of component with high trust. The static stress analysis, the nonlinear contact stress analysis and the model analysis for turbine blade is performed by ANSYS ver. 5.6. the comparison of maximum static stress around hole with maximum contact stress between pun and hole can make the cause of fracture for turbine blade clear. The difference of fatigue limit between fatigue test by standard specimen and in-service mechanical components is due to surface roughness and machining condition etc. In in-service mechanical components, Goodman diagram has to consider surface roughness for failure analysis. To find fracture mechanism of torison-mounted blade in nuclear plant. This study performs the static stress, the nonlinear contact stress and the modal analysis on torison-mounted blade with finite element method and makes the estimation for safety of turbine blade.