• Journal of Korean Academy of Fundamentals of Nursing
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• v.17 no.4
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• pp.520-530
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• 2010

Purpose: In this study influenza A (H1N1) infection control performance and stress in nurses were surveyed, to identify factors influencing stress for the nurses, and to provide basic materials for promoting infectious disease control by nurses. Method: The participants were 447 nurses who had worked at isolation clinics and/or isolation rooms in hub hospitals in the Honam region during the period of the outbreak of 2009 pandemic influenza A (H1N1) virus. Data were collected in February 2010 using self-report questionnaires. Results: The performance of participants from clinics was high for 'helping patients wearing masks', but low for 'maintaining distance over 1 meter among waiting patients'. The performance of participants from hospital rooms was high for 'putting a surgical mask on a patient going out of the room', but low for 'keeping patients' family out of the room'. The participants' stress was higher in those younger and less experienced nurses, those working at a hospital with 500-999 beds, those working at both isolation clinics and rooms, and those working at a clinic longer. Conclusion: In order to lower nurses' stress from working at isolation clinics/rooms for infectious diseases, we may need to deploy experienced nurses and limit their working days to five or less.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.1
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• pp.55-65
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• 2020

The use of underfill materials in semiconductor packages is not only important for stress relieving of the package, but also for improving the reliability of the package during shock and vibration. However, in recent years, as the size of the package becomes larger and very thin, the use of the underfill shows adverse effects and rather deteriorates the reliability of the package. To resolve these issues, we developed the package using a solid epoxy material to improve the reliability of the package as a substitute for underfill material. The developed solid epoxy was applied to the package of the application processor in smart phone, and the reliability of the package was evaluated using thermal cycling reliability tests and numerical analysis. In order to find the optimal solid epoxy material and process conditions for improving the reliability, the effects of various factors on the reliability, such as the application number of solid epoxy, type of PCB pad, and different solid epoxy materials, were investigated. The reliability test results indicated that the package with solid epoxy exhibited higher reliability than that without solid epoxy. The application of solid epoxy at six locations showed higher reliability than that of solid epoxy at four locations indicating that the solid epoxy plays a role in relieving stress of the package, thereby improving the reliability of the package. For the different types of PCB pad, NSMD (non-solder mask defined) pad showed higher reliability than the SMD (solder mask defined) pad. This is because the application of the NSMD pad is more advantageous in terms of thermomechanical stress reliability because the solderpad bond area is larger. In addition, for the different solid epoxy materials with different thermal expansion coefficients, the reliability was more improved when solid epoxy having lower thermal expansion coefficient was used.

• Ocean and Polar Research
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• v.34 no.4
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• pp.395-401
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• 2012

Ten-year AVHRR sea surface temperature data obtained in the Yellow Sea are put into EOF analyses. Temperature variation is predominated by the first mode which is associated with the seasonal fluctuation of temperature with annual range decreasing with the bottom depth. Since such a strong annual signal may mask the upwind or downwind flows occurring intermittently during the winter, only the data obtained during this season are put into EOF analyses. Every winter shows similar results. The first mode, explaining more than 90% of total variance, appears to be a part of the seasonal variation of temperature mentioned above. In the second mode, the time coefficient is well correlated with northerly winds to which the responses of the trough and shallow coastal areas are opposite to each other. A simple theoretical consideration suggests the following physical explanation: The northerly wind stress anomaly creates an upwind (downwind) flow over the trough (coastal) areas, which then induces a temperature increase (decrease) by advection of heat, and vice versa for the southerly wind stress anomaly. Hence, this paper provides further evidence of the intermittent upwind or downwind flows occurring in the Yellow Sea every winter.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1025-1028
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• 2005

Microcrystalline Si (${\mu}c-Si$) TFTs were fabricated using a conventional bottom gate amorphous Si (a-Si) process. A unique ${\mu}c-Si$ deposition technique and TFT architecture was proposed to enhance the reliability of the TFTs. This three-mask TFT fabrication process is comparable with existing a-Si TFT procesess. In order to suppress nucleation at the bottom interface of Si, before deposition of the ${\mu}c-Si$ an $N_2$ plasma passivation was conducted. A typical transfer characteristic of the TFTs shows a low off-current with a value of less than 1 pA and a sub threshold slop of 0.7 V/dec. The DC stress was applied to verify the use of ${\mu}c-Si$ TFTs for AMOLED displays. After 10,000 s of application of the stress, the off-current was even lowered and sub-threshold slope variation was less than 5%. For AMOLED displays, OLED pixel simulation was performed. A pixel current of 13 ${\mu}A$ was achieved with $V_{data}$ of 10 V. After the simulation, a linear equation for the pixel current was suggested.

• Journal of Ecology and Environment
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• v.38 no.1
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• pp.1-14
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• 2015

Whilst it is clear that increasing temperatures from global environmental change will impact the positions of alpine treelines, it is likely that a range of regional and local scaled factors will mediate the overall impact of global scale climate drivers. We summarized 12 categories of abiotic and biotic factors as 4 groups determining treeline positions. First, there are global factors related to climate-induced growth limitation and carbon limitation. Second, there are seven regional and local factors related to treeline dynamics including frost stress, topography, water stress, snow, wind, fire and non-fire disturbance. Third, species-specific factors can control treeline dynamics through their influence on reproduction and life history traits. Fourth, there are positive feedbacks in structuring the dynamics of treelines. Globally, the commonly accepted growth limitation hypothesis is that growth at a treeline is limited by temperature. Meanwhile, positive feedbacks between canopy cover and tree establishment are likely to control the spatial pattern and temporal dynamics of many treelines. The presence of non-linear dynamics at treelines has implications for the use of treelines as barometers of climate change because the lagged responses and abrupt shifts inherent in non-equilibrium systems may combine to mask the overall climate trend.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.381.2-381.2
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• 2014

In this study the amorphous carbon films were deposited by PECVD at the substrate temperature range of 250 to $600^{\circ}C$, and the process conditions of higher and lower precursor flow rate, respectively. The temperature was a main parameter to control the density and mirco-structures of carbon films, and their's properties depended with the process temperatrue are changed by controlling precursor flow rate. The precursor feeding rate affect on the plasma ion density and a deposition reactivity. This change of film properties was obtained the instrinsic stress, FT-IR & Raman analysis, refractive index (RI) and ext. coef. (k) measured by ellipsometer. In the process conditions of lower and higher flow rate of precursor it had a different intrinsic stress as a function of the substrate temperature.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.454-459
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• 2013

For the purpose of rapid development and superior design quality assurance, sophisticated finite element model for SOM(Spatial Optical Modulator) piezo actuator of MOEMS device has been developed and evaluated for the accuracy of dynamics and residual stress analysis. Parametric finite element model is constructed using ANSYS APDL language to increase the design and analysis performance. Geometric dimensions, mechanical material properties for each thin film layer are input parameters of FE model and residual stresses in all thin film layers are simulated by thermal expansion method with psedu process temperature. $6^{th}$ mask design samples are manufactured and $1^{st}$ natural frequency and 10V PZT driving displacement are measured with LDV. The results of experiment are compared with those of the simulation and validate the good agreement in $1^{st}$ natural frequency within 5% error. But large error over 30% occurred in 10V PZT driving displacement because of insufficient PZT constant $d_{31}$ measurement technology.

• Korean Journal of Optics and Photonics
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• v.8 no.5
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• pp.415-419
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• 1997

A novel fiber optic sensor is demonstrated using a FBG in PM(Polarization-Maintaining) fiber. Gratings have been written in a Bow-Tie type fiber using the phase mask. The operation of the sensor simply involves monitoring back-reflected Bragg wavelengths from the grating. Since PM fiber has two principal semi-axes with two indices of refraction, two Bragg wavelengths were observed. We have observed the position of Bragg wavelengths for PM FBG shifted simultaneously by either applying the longitudinal strain or temperature change. The wavelength sensitivity of 1.2pm/$\mu$$\varepsilon$ about a longitudinal strain and the wavelength sensitivity of 11.4pm/$^{\circ}C$ about a temperature have been experimentally achieved. The wavelength sensitivity of both longitudinal strain and temperature are approximately same with the reported values for the single mode FBG. On the other hand, the change of separation between Bragg wavelengths was observed by the applying transverse stress. We observed that the separation between two Bragg wavelengths is proportional to the applied transverse stress. The wavelength sensitivity of 14.6 pm/N about a transverse stress has been achieved. We have demonstrated PM FBG sensors can measure the transverse stress independently from the effects of temperature.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.1
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• pp.39-43
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• 2001

$SiC_{x}N$_{y}$ film is deposited by electron cyclotron resonance plasma chemical vapor deposition system using $SiH_4$(5% in Ar), $CH_4$ and $N_2$. Ternary phase $SiC_{x}N$_{y}$ thin film deposited at the microwave power of 600 W and substrate temperature of 700 contains considerable amount of strong C-N bonds. Change in $CH_4$flow rate can effectively control the residual film stress, and typical surface roughness of 34.6 (rms) was obtained. Extreme]y high hardness (3952 Hv) and optical transmittance (95% at 633 nm) was achieved, which is suitable for a LIGA mask membrane application.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.123-123
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• 2008

In this work, amorphous carbon thin films were deposited for hard mask applications by a reactive particle beam (RPB) assisted sputtering system at room temperature. The depositing characteristics of the films were investigated as functions of operating parameters such as reflector bias voltage and RF plasma power. It was confirmed that the deposition rate increased with increasing the reflector bias voltage and RF plasma power. By an atomic force microscope (AFM), it was revealed that the surface roughness was also increased. The total stress in films was determined by the use of the substrate curvature and its result will be discussed.