• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.46-52
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• 1999

Large valves for steam turbines of fossil power plants are exposed to a severe mechanical and thermal loading resulting from steam with high pressure and high temperature. Valve casings are designed to withstand such a loading. During the operation of a plant, temperatures at inner and outer surface of the casings are measured and steam flow is controlled so that the measured difference is lower than the maximum allowable value determined in the design stage. In this paper, a method is presented to calculate the maximum allowable temperature difference at the inner and outer surface of valve casings for steam turbines of fossil power plants. The finite element method is used to analyze distribution of temperature and stresses of a casing under the operating condition. Low cycle fatigue and creep rupture are taken into consideration to determine the maximum allowable temperature difference. The method can be usefully applied in the design stage of the large valves for the steam turbines, contributing to safe and reliable operation of the fossil power plants.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.23-30
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• 2003

In this study, the various load cases by specified by the IEC61400-1 international specification and GL Regulations for the wind energy conversion system were considered, and a specific composite structure configuration which can effectively endure various loads was proposed. In order to evaluate the structure, the structural analysis for the composite wind turbine blade was performed using the finite element method(FEM). In the structural design, the acceptable configuration of blade structure was determined through the parametric studies, and the most dominant design parameters were confirmed. In the stress analysis using the FEM, it was confirmed that the blade structure was safe and stable for all the considerd load cases. Moreover the safety of the blade root joint with insert bolts, newly devised in this study, was checked against the design loads and also the fatigue loads. The fatigue life for operating more than 20 years was estimated by using the well-known S-N linear damage rule, the load spectrum and Spera's empirical equations. The full-scale static test was performed under the simulated aerodynamic loads. from the experimental results, it was found that the designed blade had the structural integrity. Furthermore the measured results were agreed with the analytical results such as deflections, strains, the mass and the radial center of gravity. The studied blade was successfully certified by an international institute, GL, of Germany.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.44-54
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• 2018

Stress and fatigue of the distributor, an equipment of the high-pressure evaporator for the HRSG, were evaluated according to ASME Boiler & Pressure Vessel Code Section VIII Division 2. First, from the results of the piping system analysis model, reaction forces of the tubes connected to the distributor were derived and used as the nozzle load applied to the detailed analysis model of the distributor afterward. Next, the detailed model to analyze the distributor was constructed, the distributor being statically analyzed for the design condition with the steam pressure and the nozzle load. As a result, the maximum stress occurred at the bore of the horizontal nozzle, and the primary membrane stress at the shell and nozzle was found to be less than the allowable. Next, for the transient operating conditions given for the distributor, thermal analysis was performed and the structural analysis was carried out with the steam pressure, nozzle load, and thermal load. Under the transient conditions, the maximum stress occurred at the vertical downcomer nozzle, and of which fatigue life was evaluated. As a result, the cumulative usage factor was less than the allowable and hence the distributor was found to be safe from fatigue failure.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.233-238
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• 2011

In piping design of nuclear power plant facilities, the load stress according to self-weight is important for design values in test run(shutdown and starting). But sometimes it needs more studies, such as seismic analysis of an earthquake of power plant area and fatigue life and stress of thermal expansion and anchor displacement in operating run. In this paper, seismic evaluations were performed to nuclear piping system of Shin-Kori NO. 3&4 being built in Pusan lately. Results of seismic analysis are evaluated on basis of KEPIC MN code. The structural integrity on RCB piping system was proved.

• Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.1-7
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• 2008

Recently the wind energy has been alternatively used as a renewable energy resource instead of the mostly used fossil fuel due to its lack and environmental issues. This work is to propose a structural design and analysis procedure for development of the low noise 100W class small wind turbine system which will be applicable to relatively low speed region like Korea and for the domestic use. Structural analysis including load cases, stress, deformation, buckling, vibration and fatigue life was performed using the Finite Element Method, the load spectrum analysis and the Miner rule. In order to evaluate the designed structure, the structural test was carried out and its test results were compared with the estimated results. In addition, the blade should be safe from the impact damage due to FOD(Foreign Object Damage) including the bird strike. In order to analize the bird strike penomena on the blade, MSC. Dytran was used, and the applied method Arbitrary Lagrangian-Eulerian was evalud by comparison with the previous study results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5669-5675
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• 2012

To reduce the cost and the time of transport in Eurasian railroad networks such as TKR(Trans-Korea Railway), TCR(Trans-China Railway) and TSR(Trans-Siberia Railway) owing to the problem of different track gauges (narrow/standard/broad gauge), it is important to develop the gauge-adjustable wheelset(GAW) system to adapt easily to these gauges. The Korean GAW system is developing and will be adapting to the brand new freight trains' to improve the conventional overseas GAW system. In this study, structural and durability analyses are performed from the viewpoint of the safe-life design. The core parts of the system might be safe in range of $1{\times}10^7$ cycles from the result of durability analysis. Moreover, to examine the safety of the system while running on a track, rig fatigue test was performed according to UIC code. The safety of the Korean GAW system is demonstrated through testing that all safety-relevant conditions are satisfied.

• Journal of Korean Academy of Nursing
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• v.34 no.5
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• pp.673-684
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• 2004

Purpose: The purpose of the study was to meta-analyze the relationships of major concepts, which were made by synthesizing similar explanatory variables into more comprehensive concepts, to hope. Method: The relevant researches from Jan 1980 to Dec 2003, performed in adults or adult patients, were collected. Using the SAS program, meta-analysis were done with the input data of the number of subjects, the correlation coefficients provided from most of the studies or a few transformed correlation coefficients from F value. In order to get the analysis to be done in homogeneous status of the data regarding each relationship of each major concept to hope(p> 0.05), heterogeneous data were eliminated in repeating Q-test. Result: The major variable regarding relationship to self/transcendental being/life(spiritual wellbeing & self esteem) and social support(social support & family support) have very large positive effects on hope(D=l.72, D=l.27). The negative effect of the variable regarding captive state(uncertainty in illness, perceived unhealthiness status, & fatigue) and positive effect of coping(approach coping) on hope are in the level between moderate to large(D=-0.61, D=0.78). All the effects of the major concepts on hope were verified as significant statistically(p=.000). The Fail -Safe numbers showed the significant effects of the three major concepts except coping on hope were reliable. Conclusion: The results can be a guide to advance hope theory for nursing.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1051-1057
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• 2010

Database for the damage reference by armor piercing bullet test was established for both tube and plate specimens having a range of thickness. As the inclined angles of hit are increasing, it has been found that penetration damage diameter tends to increases accordingly in both specimen of the tube and plate, and such penetration damage diameter on the rear side becomes bigger than those on the front side. The tube specimen showed that the damage becomes bigger when central areas rather than the peripheral were hit. Through the plate test, it also has been found that the penetration ballistic limit for Al alloy is about 25.4mm and that of stainless steel about 12.7mm. From the fatigue analysis results using the database for damage reference, it has been identified whether the safety requirements of military aircraft could be met.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6932-6942
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• 2014

The expressway is a key area of road networks for national industry, economics and social development. In addition, the number of lines are increasing continuously. Recently, road management policy have shown a paradigm shift to safe road, low-carbon and green etc. Nevertheless, the road condition has deteriorated dramatically by fatigue cracking, thermal cracking and weather impact. On the other hand, the budgets for highway maintenance have shrunk dramatically. In this study, an effective pavement management and maintenance process was developed to extend the pavement serviceability and pavement life to overcome the rack of budgets.

• Journal of the Korea Convergence Society
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• v.6 no.4
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• pp.99-105
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• 2015

In order to prevent the environmental pollution nowadays, the mobile device for one person of cruiser board not used with the fossil oil has been noticed. This study aims to analyze the property of cruiser board due to the shape by carrying out the structural analysis for the safe design of cruiser board. Two models of the existing cruiser board and the cruiser board with new configuration are designed. As the structural analysis was carried out by using the finite element analysis program, the durability by deformation, stress and fatigue life was investigated. In the study result, the model of cruiser board with new configuration has the maximum deformation of 0.000971mm, the maximum stress of 0.936MPa and the fatigue life from 1827.7Cycle to $1.887{\times}105Cycle$. As all study result values at the new model became better than the existing model, the new model was seen to become more adequate at using than the existing model. This study result can be contributed to the safer and durable design of cruiser board. And it is possible to be grafted onto the convergence technique at design and show the esthetic sense.