• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.530-533
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• 2010

This paper presents numerical analysis and design optimization of various turbine blade cooling techniques with three-dimensional Reynolds-averaged Navier-Stokes(RANS) analysis. The fluid flow and heat transfer have been performed using ANSYS-CFX 11.0. A fan-shaped hole for film-cooling has been carried out to improve film-cooling effectiveness with the radial basis neural network method. The injection angle of hole, lateral expansion angle of hole and ratio of length-to-diameter of the hole are chosen as design variables and spatially averaged film-cooling effectiveness is considered as an objective function which is to be maximized. The impingement jet cooling has been performed to investigate heat transfer characteristic with geometry variables. Distance between jet nozzle exit and impingement plate, inclination of nozzle and aspect ratio of nozzle hole are considered as geometry variables. The area averaged Nusselt number is evaluated each geometry variables. A rotating rectangular channel with staggered array pin-fins has been investigated to increase heat transfer performance ad to decrease friction loss using KRG modeling. Two non-dimensional variables, the ratio of the eight diameter of the pin-fins and ratio of the spacing between the pin-fins to diameter of the pin-fins selected as design variables. A rotating rectangular channel with staggered dimples on opposite walls are formulated numerically to enhance heat transfer performance. The ratio of the dimple depth and dimple diameter are selected as geometry variables.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.2
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• pp.178-185
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• 2014

This paper describes a fabrication multiplexing sensor probe that employs a fiber Bragg grating(FBG) based on multiple measurements to determine the blade deflection of a wind power generator the reliability analysis of this probe is also presented. To diminish the temperature sensitivity of the FBG sensor, we form multiple CFRPs onto the upper and lower layers of the FBG and package it with an epoxy resin. As a result, the depth of the CFRP is 1mm, and the temperature sensitivity is $2.39pm/^{\circ}C$. We construct a sensor network utilizing the fabricated sensor with a blade beam model. As the number of pendulums is increased on the fore-end of the beam, the strain value is measured. The strain variation is calculated from the measurement of the load on the blade beam model by monitoring the strain of the FBG sensor. When the linear equation is applied, the strain error is 0.4% and when the finite difference method is used, the tip deflection error is 3.3%. The displacement error derived from the strain value of the FBG sensor is 4.39%. The calculated result between the measured value of the dead-end of the beam and the strain is less than 2.46% tip distortion error. Therefore, our proposed multiplexing sensor probe is a low-cost and high-reliability solution for a commercial wind power generator.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.1
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• pp.27-35
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• 2009

In this paper, we study the classification of steam generator tube defects using an improved feature extraction. We consider 4 axisymmetric defect patterns of tube: I-In type, I-Out type, V-In type, and V-Out type. Through numerical analysis program based on finite element modeling, 400 ECT signals are generated by varying width and depth of each defect type. From those generated ECT signals, we propose new feature vectors that include an angle between the two points where the Maximum impedance and half the Maximum impedance, and angles between Maximum impedance point and 10%, 20%, 30%, 40% of Maximum impedance points. Also, multi-layer perceptron with one hidden layer is used to classify the defect patterns. Through the computer simulation study, it is shown that the proposed method achieves an improved defect classification performance in terms of Maximum Error and mean square Error.

• The Research Journal of the Costume Culture
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• v.23 no.6
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• pp.1097-1115
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• 2015

ICT in the IOT era is the core basis of modern society. This study investigated and analyzed the recent commercialization trends of smart fashion products internationally and domestically, to utilize them as the basis of data for developing user-friendly smart fashion products that can meet the needs of consumers. Keyword research using the most representative search engines, Google and Naver was conducted for searching for various wearable items commercialized actively since 2010. The final 78 products were classified by the physical area, and the key features and benefits were analyzed. Smart fashion products were classified as four physical types for the head and face, torso, arms and hands, and ankles and feet. Smart fashion products for each body part were developed in various ways, such as hats, glasses, lenses, virtual screens, earphones, headsets, clothing, watches, wrist bands, gloves, rings, wallets, bags, anklets, shoes, socks, and insoles. The main features were music playback, bluetooth, a camera based on NFC, virtual effects, health and safety protection through measuring heartbeat and momentum, and social network sharing of all kinds of information, based on inter-working with a smartphone. These functions represent the physical, social, and emotional interactions among users and their surroundings, as well as the users, themselves. The research results are expected to be used in future studies on planning user-friendly and marketable products through in-depth analysis of the design characteristics of smart fashion products as well as consumer responses.

• Journal of Digital Convergence
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• v.13 no.4
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• pp.39-50
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• 2015

ICT convergence has attracted attention as a major means of corporate innovation. In this study in-depth interviews was had to analyze the success factors of ICT-based companies that created a performance through the convergence. The success factors of ICT convergence were analyzed by differentiating your company's products and services through the integration of ICT skills, securing convergence technologies with enhanced R&D investment, and the strong leadership of CEO and collaborative relationships at home and abroad for convergence. It is a positive impact on success of ICT convergence to try the innovations in products, to invest R&D aggressively and to construct a global partnership network. As these results, they was proposed as a policy direction for the diffusion of ICT convergence.

• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.247-255
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• 2011

Most existing clustering protocols have been aimed to provide balancing the residual energy of each node and maximizing life-time of wireless sensor networks. In this paper, we present the adaptive clustering strategy related to sink position for clustering protocols in wireless sensor networks. This protocol allows networks topology to be adaptive to the change of the sink position by using symmetrical clustering strategy that restricts the growth of clusters based on depth of the tree. In addition, it also guarantees each cluster the equal life-time, which may be extended compared with the existing clustering protocols. We evaluated the performance of our clustering scheme comparing to LEACH and EEUC, and observe that our protocol is observed to outperform existing protocols in terms of energy consumption and longevity of the network.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.2
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• pp.119-128
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• 2016

Use of ICT in Government has ability to improve service delivery to its citizens, and yet many developing countries have lagged behind in the implementation of e-Government. Many e-Government initiatives also failed to achieve their objectives in developing countries. This paper therefore aims to identify critical failure or success factors in Kenya, using Heeks' Factor Model. A survey questionnaire was developed and data were collected and analyzed from officials and interested citizens. The analysis results enabled to highlight seven specific success and failure factors, and their constituent elements in Kenya. The Kenyan overall e-Government implementation score belongs to the Zone of Improvement (3.52 of total 5.0), which means partial success or failure. The enablers of e-Government projects are good strategy formulation, and internal and external drive, whereas main failures of e-Government are weak ICT infrastructure. The areas for improvement are project management, design, competencies and funding. Data analysis highlights both strengths and weaknesses for each factor or variable. In particular, Kenyan government excels at the drive for change by top to bottom government officers as well as external stakeholders, while the government officers who are using e-Government are satisfied with the availability of vision, strategy and plan of e-Government implementation. Both technologies and e-transactions laws were the worst of all the variables in e-Government implementation. Two areas should be improved using immediate corrective action. In-depth study reveals that government officers and citizens can't fully use their laptop and mobile devices due to the lack of both ICT network and its operating technology, and legal system associated with the transaction of business information. Finally, the study ends up with recommendations for policy makers to shape the future of e-Government system in both developing and developed countries.

• The Journal of Korean Association of Computer Education
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• v.4 no.1
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• pp.161-174
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• 2001

This study is aimed at putting forward effective methods of computer education for use in schools by comparing the schools of UK and Korea. It shows : 1) a big difference in infrastructure such as H/W and Network, 2) for S/W budget UK teachers have control over their own budget, but not in Korea, 3) government, school, teacher, student, and parent all have the same mind set to promote the use of information communication technology in the UK, but in Korea the government alone drives it with its own policy. At University level, potential computer teachers in the UK are emphasized to practice fields works in schools, but in Korea, the course mainly consists of education theory and pre-teachers get only four weeks field experience. In addition, computer teachers are often those with majors in different fields, but due to the lack of interest in computer education, they are forced into these empty positions. This often leads to conflict between students and teachers because of those teachers who do not have the necessary depth in knowledge of computers.

• Journal of the Korean Home Economics Association
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• v.35 no.5
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• pp.73-102
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• 1997

The purpose of this study was to identify the specific and empirical contents in terms of first-married stepmother about her stress and efforts to adapt to her stepfamily. This studies relied on the qualitative research method in order to approach stepmother's subjective experience. There were 6 stepmother respondents who were 6 first-marrieds living in Seoul or Kyoungki area. The data was collected by in-depth personal interview.‘Open coding process’, a part of grounded theory procedures were used to analyzed the data. The major findings can be summarized as follows: 1. When focused o stressors, the stress of stepmothers were categorized into 4 categories. Those were the following: 1 When focused on stressors, the stress of stepmothers were categorized into 4 categories. Those were the following: (1) Stepmother's own problem such as stepmother' identity problem; (2) Problems within stepfamily such as problems about relations with husbands, stepchildren, and her own children; (3) Problems of stepmother family's kin such as relational problems with former spouses, in-laws, and her parent; (4) Problems of social relationship such as isolation and alienation in social relationship and neighbors' prejudice about stepmother. 2. In overcoming stress from stepfamily life and adapting to it, 4 categories were identified as important. Contents of 4 categories were such like this: (1) Stepmother's own efforts - (a) give a positive meaning to marriage or remarriage (b) flexible personality (c) situation-accepting attitude (d) exclusive management of household income (e) job (f) perseverance for time to adaptation; (2) Positive feedback within stepfamily - (a) supportive husband (b) sense of unity as a couple (c) psychological reward from stepchildren (d) existence of stepmother's own child (e) behavior for family solidarity (f) family-centered religious life; (3) Stepfamily's relationship with former spouses such as breakdown in relationship with ex-wives or ex-husbands; (4) Support from stepmothers' kin and people in social network with stepmothers. It was concluded that to reduce stress and to help adapt to stepfamily, stepmother should make an effort, and that her stepfamily and her kin should cooperate and support. In addition, negative stereotype of stepmother and stepfamily should disappeared. It was suggested that studies on stepfamily should be vitalized and that programs for preparing remarriage and counseling for stepfamily should be spread.

• Geomechanics and Engineering
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• v.22 no.4
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• pp.291-303
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• 2020

The deformation of the rock surrounding a tunnel manifests due to the stress redistribution within the surrounding rock. By observing the deformation of the surrounding rock, we can not only determine the stability of the surrounding rock and supporting structure but also predict the future state of the surrounding rock. In this paper, we used grey system theory to analyse the factors that affect the deformation of the rock surrounding a tunnel. The results show that the 5 main influencing factors are longitudinal wave velocity, tunnel burial depth, groundwater development, surrounding rock support type and construction management level. Furthermore, we used seismic prospecting data, preliminary survey data and excavated section monitoring data to establish a neural network learning model to predict the total amount of deformation of the surrounding rock during tunnel collapse. Subsequently, the probability of a change in deformation in each predicted section was obtained by using a Bayesian method for detecting change points. Finally, through an analysis of the distribution of the change probability and a comparison with the actual situation, we deduced the survey mark at which collapse would most likely occur. Surface collapse suddenly occurred when the tunnel was excavated to this predicted distance. This work further proved that the Bayesian method can accurately detect change points for risk evaluation, enhancing the accuracy of tunnel collapse forecasting. This research provides a reference and a guide for future research on the probability analysis of tunnel collapse.