• Korean Journal of Bronchoesophagology
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• v.5 no.2
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• pp.130-137
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• 1999

Background and Objectives : Provox, a recently developed tracheoesophageal prosthesis, had been widely used for voice rehabilitation after total laryngectomy for its low resistance and easiness of speech ability. But, long-term use of Provox resulted in many complications and resulted in cessation of Provox as a primary method of vocal rehabilitation. The aim of this study is to report Provox-related problems and the long-term results of Provox voice prosthesis. Materials and Methods : Medical records from patients who had undergone total laryngectomy with Provox insertion at seoul National University Hospital between January 1993 and December 1998 were reviewed retrospectively. Results : 36 patients had used 79 Provox voice prostheses during the observed period. The most common complication causing prosthesis change or removal was leakage and/or aspiration, followed by granulation formation, crusting and/or obstruction, and non-function. Median in situ lifetime of Provox was 274 days and 1-year-in situ rate was 31.0% Among 36 patients, 17 patients had undergone tracheoesophageal shunt closure at the last follow-up visit. 10 patients had complications but got along without further treatments, and 1 patient changed to Blom-Singer voice prosthesis. Only 8 patients experienced no complication, and 5 out of whom had several times of Provox change. Conclusion : long-term use of Provox resulted in discontinuation of its use due to complications in many cases. A better voice prosthesis with lower complication rate and longer in situ lifetime is needed.

• Current Photovoltaic Research
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• v.10 no.1
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• pp.16-22
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• 2022

The long-term stability of PSCs against visual and UV light, moisture, electrical bias and high temperature is an important issue for commercialization. In particular, since the operation temperature of solar cell can rise above 85℃, a study on thermal stability is required. In this study, the cause of thermal-induced degradation of PSCs was investigated using the SCAPS-1D simulation tool. First, PSCs of TiO₂/CH₃NH₃PbI₃/Spiro-OMeTAD/Au structure were exposed to a constant temperature of 85℃ to observe changes in conversion efficiency and quantum efficiency. Because the EQE reduction above 500 nm was remarkable, we simulated PSCs performance as a function of lifetime, doping density of perovskite and spiro-OMeTAD. Consequently, the main cause of thermal-induced degradation is considered to be the change in the perovskite doping concentration and lifetime due to ion migration of perovskite.

• International Commerce and Information Review
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• v.8 no.3
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• pp.385-396
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• 2006

The successful knowledge and information based companies facilitate to restructure the industry and strengthen the national competitiveness in the future. The advent of information age provides us new challenge because the information breakthrough can play a pivotal role in terms of knowledge transfer in the human resource management. Executive officer must present long term vision in order to expand enterprise continuously and establish long term management goal and strategy which are appropriate for key organizational skills of future management environment (Pfeffer, 1998). Also, long term talent management based on vision, goal and strategy and talent development strategy and employment management must be established (小池, 1994)). American HRM system's reformation cannot be defined without scientific management policy. However, currently widely discussed Japanese HRM system's reformation cannot be defined without organizational commitment focused Japanese employment system. (津田, 1992 ; 太田, 1994). Japan's development of the following policies are behind comparing to Europe : (1)Skill based talent management regardless of age, sex, nationality, race and academic background (2)Consideration of retirement age of 64 (3)Creativity and freedom promoting talent management policy. Also, there are problems to be solved. Solutions will be searched for by establishing new wage policy based on tasks and individuals in the basis of lifetime employment system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1426-1434
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• 2009

RFID/USN is considered as a key convergence technology in future ubiquitous network. In RFID/USN, the power saving issue receives a great attention due to limited battery lifetime of sensor node. In this paper, we propose a new power saving algorithm, which takes advantage of long-term sleep period. To provide a full network connectivity and balance the battery consumption among sensor nodes, the proposed algorithm intelligently selects the long-term sleep sensor nodes. With mathematical analysis and simulations, we prove that the proposed algorithm can significantly reduce the power consumption of sensor nodes as compared to existing algorithms.

• Structural Engineering and Mechanics
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• v.52 no.6
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• pp.1257-1271
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• 2014

The hydraulic deterioration of the drainage system in tunnel linings is one of the main factors governing long-term lining-ground interactions during the lifetime of tunnels. Thus, in the design procedure of a tunnel below the groundwater table, the possible detrimental effects associated with the hydraulic deterioration should be addressed. Hydraulic deterioration in double-lined tunnels can occur because of reasons such as clogging of the drainage layer and drain-pipe blockings. In this study, the coupled mechanical and hydraulic interactions between linings due to drain-pipe blockings are investigated using the finite-element method. A double-lined structural model incorporating hydraulic behavior is developed to represent the coupled structural and hydraulic behavior between the linings and drainage system. It is found that hydraulic deterioration hinders flow into the tunnel, causing asymmetric development of pore-water pressure and consequent detrimental effects to the secondary lining.

• Journal of Applied Reliability
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• v.11 no.2
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• pp.111-126
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• 2011

The clutch coil mounted on the automotive air conditioner is an important part which actuates the clutch to connect or disconnect the pulley and the compressor according to the climate control condition in an automobile. Here, it is generally required that the clutch coil should ensure the long term durability requirement, such as a warranty for the 10 years of field operation or 160,000 km driving, especially in a brand new item, and so forth. However, some difficulties have arisen in restoring its credibility, since domestic specifications for the part have not been yet unified. In order to ensure the reliability, test methods and assessment criteria should be standardized. Moreover, assessed lifetime under specific conditions and potential failure analysis would be important. In this study, lifetime test specifications for the clutch coil have been reviewed and methodological suggestions are provided to ensure reliability, utilizing a quality function deployment through the potential failure mode effect analysis.

• Safety and Health at Work
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• v.10 no.4
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• pp.428-436
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• 2019

Background: Metalworking fluids (MWFs) are mixtures with inhalation exposures as mists, dusts, and vapors, and dermal exposure in the dispersed and bulk liquid phase. A quantitative risk assessment was performed for exposure to MWF and respiratory disease. Methods: Risks associated with MWF were derived from published studies and NIOSH Health Hazard Evaluations, and lifetime risks were calculated. The outcomes analyzed included adult onset asthma, hypersensitivity pneumonitis, pulmonary function impairment, and reported symptoms. Incidence rates were compiled or estimated, and annual proportional loss of respiratory capacity was derived from cross-sectional assessments. Results: A strong healthy worker survivor effect was present. New-onset asthma and hypersensitivity pneumonitis, at 0.1 mg/㎥ MWF under continuous outbreak conditions, had a lifetime risk of 45%; if the associated microbiological conditions occur with only 5% prevalence, then the lifetime risk would be about 3%. At 0.1 mg/㎥, the estimate of excess lifetime risk of attributable pulmonary impairment was 0.25%, which may have been underestimated by a factor of 5 or more by a strong healthy worker survivor effect. The symptom prevalence associated with respiratory impairment at 0.1 mg/㎥ MWF was estimated to be 5% (published studies) and 21% (Health Hazard Evaluations). Conclusion: Significant risks of impairment and chronic disease occurred at 0.1 mg/㎥ for MWFs in use mostly before 2000. Evolving MWFs contain new ingredients with uncharacterized long-term hazards.

• Current Photovoltaic Research
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• v.5 no.2
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• pp.47-54
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• 2017

We report finding ways to improve the long-term reliability of PV module including the heterostructure with the intrinsic thin layer (HIT) solar cell. We point out the stability of the products of Panasonic HIT cell. We account for a brief description of the module manufacturing process to investigate the issues of each process and analyze the causes. We carried out the silicon PV module of the glass to glass type under the damp heat test around 1000 hours. However, it degraded around 7% of PV module power after 300 hours exposure in comparison with the initial status (Initial: 12.7 Watt). We investigated possible cause and solutions for the module performance to develop the long-term reliability.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.970-973
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• 1999

When the size of the device is decreased, the hot carrier degradation presents a severe problem for long-term device reliability. In this paper we fabricated & tested the 0.26${\mu}{\textrm}{m}$ NMOSFET with wet gate oxide and nitride oxide gate to compare that the characteristics of hot carrier effect, charge to breakdown, transistor Id_Vg curve and charge trapping using the Hp4145 device tester As a result we find that the characteristics of nitride oxide gate device better than wet gate oxide device, especially a hot carrier lifetime(nitride oxide gate device satisfied 30years, but the lifetime of wet gate oxide was only 0.1year), variation of Vg, charge to breakdown and charge trapping etc.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.spc
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• pp.51-62
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• 2020

In this paper, an approach developed by the Finnish nuclear waste management organization, Posiva, for the construction license of a geological repository was reviewed. Furthermore, a computer program based on the approach was developed. By using the computer program, the lifetime of a copper disposal canister, which was a key engineered barrier of the geological repository, was predicted under the KAERI Underground Research Tunnel (KURT) geologic conditions. The computer program was developed considering the mass transport of corroding agents, such as oxygen and sulfide, through the buffer and backfill. Shortly after the closure of the repository, the corrosion depths of a copper canister due to oxygen in the pores of the buffer and backfill were calculated. Additionally, the long-term corrosion of a copper canister due to sulfide was analyzed in two cases: intact buffer and eroded buffer. Under various conditions of the engineered barrier, the corrosion lifetimes of the copper canister due to sulfide significantly exceeded one million years. Finally, this study shows that it is necessary to carefully characterize the transmissivity of rock and sulfide concentration during site characterization to accurately predict the canister lifetime.