• Journal of Aerospace System Engineering
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• v.15 no.3
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• pp.93-98
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• 2021

In Europe, it is necessary to fulfil the type certification criteria by the European Aviation Safety Agency (EASA) when developing an aircraft engine. According to type certification criteria, a 150 hours endurance test should be performed to verify the stability of the engine structure under the engine's operating limit conditions. The type certification criteria for the 150 hour endurance test are specified in JAR-E, which is the EASA type certification. Currently, the Arriel 2L2 engine is being developed in cooperation with a foreign manufacturer, and a 150 hours endurance test was performed. In this study, a 150 hours endurance test procedure is conducted in consideration of the operation characteristics of the currently developed engine.

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.67-72
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• 2012

In this study, the leak-free performance and sealing endurance safety of CNG fueling nipple in which are related to the contact normal stress and equivalent true stress have been analyzed for CNG automobile using a finite element analysis. For the conventional circular o-rings and new double-lip o-rings with an initial compression rate of 15 percentages, the leak-free performance of double-lip o-rings with two contact sealing spots is 41% higher than that of the conventional circular o-rings with a contact sealing spot. The FEM computed results present that the leak-free endurance safety of double-lip o-rings with two contact sealing spots is 5% higher than that of the conventional circular o-rings for initial compression ratio of 15 percentages and a gas compression pressure of 8MPa. And, the maximum equivalent true stress of double-lip o-rings is 10.2% higher than that of the conventional circular o-rings for the leak-free endurance safety. This means that the double-lip o-ring may guarantee the extended sealing life compared to that of a conventional circular o-ring.

• Journal of the Korean Institute of Gas
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• v.17 no.1
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• pp.73-80
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• 2013

This study presents sealing behavior and endurance safety of V-grooved o-rings as functions of a strain, compression stress, and contact normal stress using a FEM technique. The FEM results on the sealing behavior and endurance safety show that the maximum strain, maximum compression stress, and maximum contact normal stress of V-grooved o-rings are approximately 1.2 times higher than those of conventional solid o-rings. This is why that an o-ring has a V-groove in the center between two overlapped circles, which is very effective in sealing for ball valves, pressure vessels, and gas equipment. And the extrusion failure in V-grooved o-rings does not take place under an increased gas pressure due to a V-groove. This may extend sealing life compared with that of a conventional solid o-ring.

• Earthquakes and Structures
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• v.10 no.2
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• pp.429-450
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• 2016

An attempt has been made to incorporate the concept of collapse safety margin into the procedures proposed in the performance-based earthquake engineering (PBEE) framework for direct earthquake loss estimation, in which the collapse probability curve obtained from incremental dynamic analysis (IDA) is mathematically characterized with the S-type fitting model. The regressive collapse probability curve is then used to identify non-collapse cases and collapse cases. With the assumed lognormal probability distribution for non-collapse damage indexes, the expected direct earthquake loss ratio is calculated from the weighted average over several damage states for non-collapse cases. Collapse safety margin is shown to be strongly related with sustained damage endurance of structures. Such endurance exhibits a strong link with expected direct earthquake loss. The results from the case study on three concrete frames indicate that increase in cross section cannot always achieve a more desirable output of collapse safety margin and less direct earthquake loss. It is a more effective way to acquire wider collapse safety margin and less direct earthquake loss through proper enhancement of reinforcement in structural components. Interestingly, total expected direct earthquake loss ratio seems to be insensitive a change in cross section. It has demonstrated a consistent correlation with collapse safety margin. The results also indicates that, if direct economic loss is seriously concerned, it is of much significance to reduce the probability of occurrence of moderate and even severe damage, as well as the probability of structural collapse.

• The Journal of the Korea Contents Association
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• v.14 no.5
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• pp.272-280
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• 2014

This study was researched by practical method in a subjectivity study accessible in-depth, in sloughing off old habit of functional quantity analysis about utility awareness of medical machinery. The perception pattern come out in this study were divided into three types in Q-methodology. The result is as follows ; it is that divided '1[(N=11) : Safety & Importance of Advertising 1], 2[(N=9) : Safety & Importance of Advertising 2], 3[(N=10) : Safety & Endurance]'. Like this, it found that is very different type all over. Hereafter, this study is to ascertain acceptance behavior about reception type on utility awareness of medical machinery ; to offer a developmental suggestion about it.

• Journal of Aerospace System Engineering
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• v.10 no.2
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• pp.7-13
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• 2016

Multi disciplinary approach for aerodynamics, structure, propulsion, and flight control system is necessary to develop High Altitude Long Endurance Unmanned Aerial Vehicles (HALE UAV). Various HALE UAV development trends are surveyed to understand their operational requirements. Separating the UAV Take Off Weight by 150kg, Airworthiness implementation direction for HALE UAV is studied under the current Airworthiness regulations. NATO STANAG 4671 and STANAG 4703 Airworthiness certification criteria are analyzed, and their applicability was proposed for future HALE UAV development. In addition, minimization of the risk for UAV is studied by considering probability of cumulative catastrophic failure for HALE UAV. This Hazard Risk Index can support the future UAV Airworthiness Certification Criteria.

• 한국기계연구소 소보
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• s.13
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• pp.3-13
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• 1984

Fatigue failure of axle housing could cause many injuries and much financial loss. This challenges the engineer to improve design decisions involving fatigue. Endurance evaluation of axle housing is great interest to auto-mobile manufacturers for the sake of safety and reliability. Axle housing is subjected to gross vehicle weight(G.V.W)as mean load and alternating load. Theoretical design diagram involving mean and alternating stresses is used for the evaluation of axle housing fatigue endurance with the equivalent stress of fatigue critical area on the axle housing. Four point bending fatigue tests on axle housing with constant amplitude loading at approximately R=0 were performed with 50 ton servohydraulic strucural fatigue testing machine developed at KIMM. Specimens were made with the same material STKM 13B as the axle housing and tested to obtain S_N data. Five specimens of STKM 13B were tested at 253.61 MPa and weibull distribution was obtained at the same stress level. Material data and structural data were compares and fatigue stress property factor and fatigue life property factor were obtained.

• Korean Journal of Occupational Health Nursing
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• v.8 no.1
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• pp.5-21
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• 1999

The purpose of this study is to evaluate the physical fitness status and health promoting life styles of the workers. For the purpose, 108 workers who attended the exercise program in Inchon branch of KISCO were selected as the subjects. From Oct. 20th to Nov. 30th, in 1998, they were firstly assessed their physical fitness. The items include cardio-respiratory endurance, flexibility, muscular strength, muscular endurance, agility, power, balance, body composition, etc. Secondly, the health promoting life styles were asked by questionnaires about daily life and dietary habits. Both of them were evaluated by 5 or 3 levels as A(very good) to E(very poor) or A (good) to C(poor). Those data were analyzed percentile, mean, standard deviation by SAS program. Major findings are as follows ; 1. The health promoting life styles were generally good, but 43.5% of the subjects didn't exercise at all. Most of them(93.5%) thought about their physical fitness status as lower than average level. About half of them(48.1%) didn't drink alcohol, non smokers were 70.4% of them. But they had poor dietary habits(lower than average level : 79.6%), females were a little bit better than males. The aged group had the poor body compositions, 21.4% of females and 10.0% of males were obese. 2. Physical fitness status of the workers were assessed as two areas, one is health related, the other is physical function related area. In the health related area, females were better than males, in view of age, forties aged group had the highest scores of all items except cardio-respiratory endurance. Among 'A' and 'B' level, muscular endurance was showed most frequently, followed by muscular strength, flexibility, cardiorespiratory endurance. In physical function related status, balance was ranked highly in the portion of over 'B', followed by power, agility. In view of sex, males were better than females for all items except balance, and there were various figures in the status by age groups. 3. Comprehensive assessment scores were poor(under 'D' leves were most frequent), females were better than males, and teenage group had the worst scores. In ages of the physical fitness, generally they had 1 year under their real ages, and females were better than males. In view of age, forties aged group was ranked highly and teenagers had lowest scores.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.1
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• pp.69-81
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• 2010

Physical manifestations of aging due to the lack of exercise include the slowing down of motor learning, cardiopulmonary degradation, and the increasing difficulty to adapt to the environment. Aging is manifested with the lack of aerobic exercise work, decrease in muscular endurance, decline in skeletal and muscular strength, flexibility and agility, and the decrease in reaction speed and balance. Added to those are aging-related physiological changes, including the reduction of muscle bulk, increased body fat, decrease in total body water and basic metabolic rate as activities are reduced, and a decrease in cell and Lean Body Mass (LBM). These changes are known to cause problems. Interest and participation in appropriate physical activities among the elderly is needed to help them increase stamina, avoid diseases, maintain a clear intellect, and basically enable the elderly to live their daily lives as easy as possible. Therefore, physical activities are necessary for the elderly to enhance health-related factors. Special exercises should be performed for the enhancement of muscle function, muscle endurance, flexibility, agility, and balance. An accurate measurement of cardio-respiratory endurance and stamina through basic physical and cognitive characteristics of older adults is also required to ensure safety. Also, the development of a more scientific resistance exercise prescription system for the elderly is desperately needed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.836-839
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• 2005

A limit switch box is used for a indicator of a valve actuator. This device indicates an opening and closing of a valve or throttle in a valve actuator. In a ship, equipments are required safety and robustness because of a rough environment and a specific condition during a voyage. However, the limit switch box is used in an indoor environment generally. In order to evaluate the endurance of the limit switch box used in an indoor environment, the endurance tests against salt water have been conducted. Experiment results showed that the limit switch box was corroded severely. Thus, this study developed a new limit switch box which can be used at an outdoor environment. The housing of the developed limit switch box was made by an stainless steel to prevent corrosion.