• Proceedings of the KIEE Conference
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1448-1450
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• 2003

The suspension insulators are subjected to harsh environment in service for a long time. Long term reliability of the insulators is required for both mechanical and electrical performances. We studied an analysing method to find out a deformation of brittle porcelain with a thermal expansion of simulation analysis and experimental results show that cement volume growths affect severely to be mechanical failure ageing.

• Proceedings of the KIEE Conference
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.241-244
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• 1991

In this paper, we introduced Silicon Oxynitride films deposited by Laser CVD, and evaluated the electrical breakdown of these films by TZDB(Time Zero Dielectric Breakdown) and TDDB(Time Dependent Dielectric Breakdown) test. In addition, high frequency C-V test was done in order to calculate hysterisis and flatband voltage(before and after electric field stress). Failure times against eletric field are examined and electric field accelation factor $\beta$ are obtained, and long term reliability was also described by extrapolating into life time in the operating voltage(5V). In this experiments, the deposited films with increased temperature represented small flatband voltage, hysterisis and favorable breakdown characteristics, this is why the hydrogen in the film was decreased and the film was densified, long term reliability was good in the laser CVD SiON films.

• International Journal of Highway Engineering
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• 제19권5호
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• pp.1-11
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• 2017

PURPOSES : This study is aimed at development of a stochastic pavement deterioration forecasting model using National Highway Pavement Condition Index (NHPCI) to support infrastructure asset management. Using this model, the deterioration process regarding life expectancy, deterioration speed change, and reliability were estimated. METHODS : Eight years of Long-Term Pavement Performance (LTPP) data fused with traffic loads (Equivalent Single Axle Loads; ESAL) and structural capacity (Structural Number of Pavement; SNP) were used for the deterioration modeling. As an ideal stochastic model for asset management, Bayesian Markov multi-state exponential hazard model was introduced. RESULTS:The interval of NHPCI was empirically distributed from 8 to 2, and the estimation functions of individual condition indices (crack, rutting, and IRI) in conjunction with the NHPCI index were suggested. The derived deterioration curve shows that life expectancies for the preventive maintenance level was 8.34 years. The general life expectancy was 12.77 years and located in the statistical interval of 11.10-15.58 years at a 95.5% reliability level. CONCLUSIONS : This study originates and contributes to suggesting a simple way to develop a pavement deterioration model using the total condition index that considers road user satisfaction. A definition for level of service system and the corresponding life expectancies are useful for building long-term maintenance plan, especially in Life Cycle Cost Analysis (LCCA) work.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.196-203
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• 2008

Durability of geosynthetics for soil reinforcement is accounted for creep and creep rupture, installation damage and weathering, chemical and biological degradation. Among these, the long-term creep properties have been considered as the most important factors which are directly related to the failure of geosynthetic-reinforced soil(GRS). However, the creep test methods and strain limits are too various to compare the test results with each other. The most widely used test methods are conventional creep test, time-temperature superposition and stepped isothermal method as accelerated creep tests. Recently developed design guidelines recommend that creep-rupture curve be used to determine the creep reduction factor($RF_{CR}$) which is a conservative approach. In this study, the different creep test methods were compared and the creep reduction factors were estimated at different creep strain limits of 10% of total creep strain and creep rupture. In order to minimize the impact of creep strain to the GRS structures, the various creep reduction factors using different creep test methods should be investigated and then the most appropriated one should be selected for incorporating into the design.

• Journal of the Korean Solar Energy Society
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• 제26권3호
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• pp.1-8
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• 2006

The objective of this research is to study on the analysis of long-term performance characteristics of various solar thermal system for heating protected horticulture system for reducing heating cost, increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Long term field test for the demonstration was carried out in horticulture complex in Jeju Island. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Optimum operating condition and its characteristics were closely investigated by changing the control condition based on the temperature difference which is the most important operating parameter. However, it is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• Journal of Korean Public Health Nursing
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• 제29권2호
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• pp.203-218
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• 2015

Purpose: The purpose of this study is to find and suggest ways to invigorate operation of visiting nursing centers. Methods: SWOT analysis was performed based on the status of use of visiting nursing centers and opinion survey on the centers' nursing experts. Results: SO strategy was drawn to improve service satisfaction, develop standardized manuals, and improve the areas of visiting nursing services, and WO strategy was drawn to establish reliability, strengthen promotion or marketing strategy, strengthen management ability, and reinforce the governmental support of visiting nursing services. ST strategy was drawn to recover the functionality of health management, secure competitive advantage, and simplify the issuance of visiting nursing directions, and WT strategy was drawn to provide customized service, establish the cooperative system of related agencies, and adjust fees. Conclusion: For invigoration of visiting nursing centers, people must recognize the importance of the visiting nursing service and institutional standards should be established so that visiting nursing service, which is currently provided as an option according to Standard Long-Term Care Plan, can be provided on a mandatory basis.

• Research in Community and Public Health Nursing
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• 제24권3호
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• pp.332-345
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• 2013

Purpose: This study was attempted to provide quality improvement and revitalization of visiting nurse services by Importance-Performance Analysis of persons being provided with the services. Methods: The subjects were 350 people being provided with visiting nurse services from a long term home care institution in the kangwon Province during the period of data collection between Aug. 16 and Sep. 15, 2011. Data analysis was conducted through t-test, ANOVA, and IPA by using the SPSS/WIN 12.0 program. Results: As a result of the Importance-Performance Analysis of visiting nurse services, it turned out that the strength on reliability, assurance, and empathy should be maintained with good work and the aspects of responsiveness appeared to be intensively improved, and the tangibility proved to be subject to improvement. Conclusion: For the activation of visiting nurse services, methods for improving the performance in the intensive care area and management strategy establishment which highlights the advantages of strength maintenance area are needed.

• Journal of the Korean institute of surface engineering
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• 제43권2호
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• pp.64-72
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• 2010

CuSnZn electroplating was investigated as alternative to Ni plating. Evaluation of electrolyte and plating process was performed to control physical characteristics of the film, and to collect practical data for application. Hull-cell test was conducted for basic comparison of two commercialized products and developed product. Based on hull-cell test results, long term test of three electrolytes was performed. Various analysis on long term tested electrolyte and samples have been done. Reliable and practical data was collected using FE-SEM (FEI, Sirion), EDX (ThermoNoran SIX-200E), ICP Spectrometer (GBC Scientifi c, Integra XL), FIB (FEI, Nova600) for anlysis. Physical analysis and reliability test of the long term tested film were also carried out. Through this investigation plating time, plating speed, electrolyte composition, electrolyte metal consumption, hardness and corrosion resistance has been compared. This set of data is used to predict and control the chemical composition of the film and modify the physical characteristics of the CuSnZn alloy.

• ETRI Journal
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• 제43권2호
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• pp.232-245
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• 2021

As wireless communication continues to develop in limited frequency resource environments, it is becoming important to identify the state of spectrum utilization and predict the amount needed in future. It is essential to collect reliable information for data analysis. This paper introduces a platform that enables the gathering of the scheduling information of a long-term evolution (LTE) cellular system without connecting to the network. A typical LTE terminal can confirm its assigned resource information using the configuration parameters delivered from a network. However, our platform receives and captures only the LTE signal over the air and then enables the estimation of the data relevant to scheduling for all terminals within an LTE cell. After extracting the control channel signal without loss from all LTE subframes, it detects valid downlink control information using the proposed algorithm, which is based on the error vector magnitude of depatterned symbols. We verify the reliability of the developed platform by comparing it with real data from mobile phones and service operators. The average difference in resource block utilization is only 0.28%.

• Architectural research
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• 제23권2호
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• pp.19-28
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• 2021

Reduction in competence makes older adults with dementia more sensitive to the influence of the physical environment. The aim of the longitudinal study was to examine whether residents with dementia in long-term facilities with variability in physical environmental characteristics in Vancouver (N= 11), Canada and Stockholm (N=13), Sweden had a difference in their quality of life (QoL). QoL was assessed using Dementia Care Mapping tool three times over one year for the reliability of data. The results of the study demonstrated that the residents with dementia living in a homelike and positive stimulating setting showed less withdrawn behaviors and a higher level of well-being compared to those in a large-scale institutional setting. This study also found that the residents living in a large-scale institutional environment spent more monotonous times than the other groups, which may be to provision of fewer structured activity programs or less social interaction with neighbors or staff members. Residents living in a large-scale institutional setting in Canada showed so far as five times more agitated/ distressed behaviors and twice more withdrawal compared to the ones living in a small-scale homelike setting in Sweden. The study supports that the large-scale institutional environment was considerably associated with levels of lower quality of life among the residents with dementia.