• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2901-2906
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• 2007

A solver for icing and condensation of water has been developed. The phase change process was solved by the enthalpy method. For the code validation, the temperature and the phase change from water to ice of the driven cavity were calculated. Also, the melting process of the frost on the windshield glass of an automobile has been simulated. The calculation showed a good agreement with analytical solution and other numerical results. Using the present validated code, the condensation of water vapor has been first tried. The computed results provided some physical features of condensation phenomena even though experimental data and other numerical data were not available. For future work, it is recommended to throughly investigate the effects of boundary conditions on the solution.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.84-89
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• 2014

Data-driven method for fault diagnostics system often use machine learning technique. To use such technique proper signal processing should be implemented such as time synchronous averaging (TSA) for ball bearing systems. However, for journal bearing diagnostics systems not much has been researched, and yet a proper signal processing method has not been studied. Therefore, in this research an optimal datum unit for a reliable journal bearing diagnostics system along with angular resampling process is being suggested. Before extracting time and frequency domain features, angular resampling is applied to each cycle of vibration data. As to preserve the characteristics of vibration signal, averaging method is replaced by finding the optimal datum unit which strengthens statistical characteristics of vibration signal. Then 20 features were extracted for various cases, and those features are being evaluated by two criteria, separability and classification accuracy.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.470-473
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• 2009

We have developed a novel driving method, Six times Rate Driving(SRD) for the purpose of making cost competitive TFT-LCD. By applying SRD method to an a-Si TFT-LCD, the driving rate was increased six times as it was named but the number of data lines and so its D-Ics were reduced to one sixth of the conventional one which resulted in the cost saving of that much. We also newly designed the gate driver in order to avoid any expansion of the bezel width caused by applying SRD. Our newly developed driving technology, SRD was successfully applied to 7.0-inch WSVGA (1024 ${\times}$ 600) TFT-LCD which can be driven with only one data D-IC and here introduced.

• Speech Sciences
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• v.10 no.1
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• pp.71-84
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• 2003

In the acoustic modeling for large vocabulary speech recognition, a sparse data problem caused by a huge number of context-dependent (CD) models usually leads the estimated models to being unreliable. In this paper, we develop a new clustering method based on the C45 decision-tree learning algorithm that effectively encapsulates the CD modeling. The proposed scheme essentially constructs a supervised decision rule and applies over the pre-clustered triphones using the C45 algorithm, which is known to effectively search through the attributes of the training instances and extract the attribute that best separates the given examples. In particular, the data driven method is used as a clustering algorithm while its result is used as the learning target of the C45 algorithm. This scheme has been shown to be effective particularly over the database of low unknown-context ratio in terms of recognition performance. For speaker-independent, task-independent continuous speech recognition task, the proposed method reduced the percent accuracy WER by 3.93% compared to the existing rule-based methods.

• Smart Structures and Systems
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• v.23 no.1
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• pp.15-29
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• 2019

This paper addresses the problem of damage detection in suspension bridge hangers, with an emphasis on the modal flexibility method. It aims at evaluating the capability and the accuracy of the modal flexibility method to detect and locate single and multiple damages in suspension bridge hangers, with different level of severity and various locations. The study is conducted numerically and experimentally on a laboratory suspension bridge mock-up. First, the covariance-driven stochastic subspace identification is used to extract the modal parameters of the bridge from experimental data, using only output measurements data from ambient vibration. Then, the method is demonstrated for several damage scenarios and compared against other classical methods, such as: Coordinate Modal Assurance Criterion (COMAC), Enhanced Coordinate Modal Assurance Criterion (ECOMAC), Mode Shape Curvature (MSC) and Modal Strain Energy (MSE). The paper demonstrates the relative merits and shortcomings of these methods which play a significant role in the damage detection ofsuspension bridges.

• Journal of the Korean Society of Visualization
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• v.19 no.2
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• pp.32-40
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• 2021

Vapor-driven solutal Marangoni flow is governed by the concentration distribution of solutes on a liquid-gas interface. Typically, the flow structure is investigated by particle image velocimetry (PIV). However, to develop a theoretical model or to explain the working mechanism, the concentration distribution of solutes at the interface should be known. However, it is difficult to achieve the concentration profile theoretically and experimentally. In this paper, to find the concentration distribution of solutes around 2D droplet, the reverse tracking method with an artificial neural network based on PIV data was performed. Using the method, the concentration distribution of solutes around a 2D droplet was estimated for actual flow data from PIV experiment.

• Child Health Nursing Research
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• v.14 no.1
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• pp.99-110
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• 2008

Purpose: This study was done to identify the relationship between smoking, drinking and safety behavior in middle and high school students in one Korean province, North Cholla. Method: The study sample included 1,327 randomly selected middle and high school students from S-Gun area in Chonbuk Province. The data were collected using an anonymous questionnaire developed by the Ministry of Health and Welfare (2005). The data were analyzed using the SPSSWIN 15.0 program. Results: The smoking rate in the middle and high school students was 6.9%, and the drinking rate was 24.9%. The rate for seatbelt use was 49.3%, for drunk driving, 8.8%, and for riding in car driven by a drunk driver, 24.0%. The rates for seatbelt use, for drunk driving, and for riding in a drunk driver were higher in smokers and drinkers than in non-smokers and non-drinkers(p<.05). Conclusion: The smoking and drinking status of the adolescents was correlated with their safety behavior practices as they relate to seatbelt use, drunk driving, and for riding in car driven by a drunk driver. Therefore, an elementary school level program to curb student smoking and alcohol consumption is needed to prevent smoking and alcohol consumption in middle and high school students and contribute to improvement in their safety behavior practices.

• Proceedings of the KSRS Conference
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• v.2
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• pp.672-675
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• 2006

The geostrophic current component is estimated from the sea surface velocity observed by the long-range High-Frequency Ocean Radar (HF radar) system in the upstream of the Kuroshio, by comparing with geostrophic velocity determined from along-track T/P and Jason-1 altimetry data. However, the sea surface velocity of the HF radar (HF velocity) contains not only the geostrophic current but also the ageostrophic current such as tidal current and wind-driven Ekman current. Tidal current component is first extracted by the harmonic analysis of the time series of the HF velocity. Then, the Ekman current is further estimated from daily wind data of IFREMER by applying the least-square method to the residual difference between the HF velocity and the altimetry geostrophic velocity. As a result, the Ekman current in the HF velocity is estimated as 1.32 % of the wind speed and as rotated 45$^{\circ}$ clockwise to the wind direction. These parameters are found almost common in the Kuroshio area and in the Open Ocean. After these corrections, the geostrophic velocity component in the HF velocity agrees well with the altimetry geostrophic velocity.

• Women's Health Nursing
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• v.14 no.1
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• pp.44-55
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• 2008

Purpose: This study was done to assess the personal experiences of the coping process during pregnancy for single mothers. Methods: The participants were 17 single mothers who had stayed in a social welfare facility. Data was collected with an in-depth unstructured interview. Data analysis was done by the grounded theory method. Results: One-hundred twelve concepts and 49 sub-categories were confirmed in the analysis. The sub-categories were grouped into 19 categories; escape from a miserable family, wrong meeting, openness of sex, defenseless state of pregnancy, inevitable result of pregnancy, heartbreak by herself, closure, isolation, difficult situation of being alone, stigma, supporting & protecting, helplessness, seeking, empowering, feeling of loss, conflict, facing issues, assuring a fresh start and becoming-mature. "Being driven over the edge of a cliff" was the key phenomenon which the single mothers experienced during the process of pregnancy. Conclusion: The above results will help nurses assessing single pregnancy mothers' needs and developing a nursing intervention program for supporting them. Therefore, nurses will be able to stop them from "being driven over the edge of cliff". A more vigorous nursing intervention is suggested for the research of the vulnerable classes of medical health care including single pregnant mothers.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.2
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• pp.177-188
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• 2001

The paper presents the method to estimate the bottom shear stress driven by waves and current on rough turbulent flow. Parameter adjusting technique is suggested for the computation of bed shear stress driven by uni-directional flow, and the value ofpararneter is determined by comparing the computational results against Bijker's laboratory data. For the computation of combined flow bottom shear stress, two methods are presented; one is the modified Bijker approach (BYO Model) and the other is the modified Fredsoe approach (FY Model), both of which are refined by the present writers. BYO model is again refined in the computation of maximum shear stress, and the final version is tested against Bijkcr's laboratory data.