• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.461-465
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• 2016

n-type silicon shows the better tolerance towards metal impurities with a higher minority carrier lifetime compared to p-type silicon substrate. Due to better lifetime stability as compared to p-type during illumination made the photovoltaic community to switch toward n-type wafers for high efficiency silicon solar cells. We fabricated the front electrode of the n-type solar cell with AgAl paste. The electrodes characteristics of the AgAl paste depend on the contact junction depth that is closely related to the firing temperature. Metal contact depth with p+ emitter, with optimized depth is important as it influence the resistance. In this study, we optimize the firing condition for the effective formation of the metal depth by varying the firing condition. The firing was carried out at temperatures below $670^{\circ}C$ with low contact depth and high contact resistance. It was noted that the contact resistance was reduced with the increase of firing temperature. The contact resistance of $5.99m{\Omega}cm^2$ was shown for the optimum firing temperature of $865^{\circ}C$. Over $900^{\circ}C$, contact junction is bonded to the Si through the emitter, resulting the contact resistance to shunt. we obtained photovoltaic parameter such as fill factor of 76.68%, short-circuit current of $40.2mA/cm^2$, open-circuit voltage of 620 mV and convert efficiency of 19.11%.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.1-14
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• 1996

Especially in the case of a full form ship, the stability on course can be considered to become severest among 4 items of criteria in Interim Standards for Ship Maneuverability adopted by IMO in 1993. The purpose of this study is to find some ideas for the improvement of stability on course through changes in rudder area with reference to span distance. In this paper, we established the formula on the relation between the experimental constants relevant to rudder normal force and hydrodynamic derivatives of hull-propeller-rudder system. We carried out various kinds of captive model test relevant to rudder normal force etc., and evaluated hydrodynamic derivatives of hull-propeller-rudder system, and analyzed the stability on course with the parameter of changes in rudder area. Furthermore, we also discussed effects of changes in rudder area on maneuvering performance including stability on course, based on computer simulation. As a result, it is clarified that there is a possibility that stability on course may become bad through an increase of rudder area. The reason for the bad stability on course is that the void space between the upper edge of rudder and the lower part of stern overhang decreases. This space change exerts a great influence on straightening coefficient of incoming flow to rudder in maneuvering motion, which has close relation to stability on course.

• Journal of Service Research and Studies
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• v.9 no.2
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• pp.41-54
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• 2019

The increasing use of mobile applications is a phenomenon that has recently come to be beneficial to people in their private life due to increased income and changes in life style. In particular, analyzing customers' consumer sentiment can be seen as a pursuit form of convenience that enables efficient use of time and effort. In this study, based on previous studies, we examine the causal relation model that influences reuse intention, which is a dependent variable through perceived value as a parameter by measuring the service convenience for cafe mobile application. In order to accomplish purpose of this study, references related to service convenience, perceived value, and reuse intention were reviewed as literature research methods. For the empirical study, the research was carried out through Macro Mill Embrain Co., Ltd. Online research was conducted for one week from October 26 to November 8, 2018. There are 13 items of the collected data were excluded and 324 items suitable for irradiation were used. Study results show that service convenience of cafe mobile application has a positive effect on perceived value and reuse intention. In addition, in the relationship that cafe mobile app's service convenience has a significant (+) influence on reuse intention, perceived value proved to have meaningful results as intermediary roles. Implications of this study are as follows. First of all, this study will be helpful for cafe companies and consumers if utilize the service convenience of cafe mobile application in perceived value and reuse intention in marketing applications. Therefore, theoretically, we propose the development direction of cafe mobile application and present academic data for marketing strategy innovation and competitive advantage in the food service industry that conforms to the fourth industrial revolution era.

• Korean Journal of Health Education and Promotion
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• v.21 no.2
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• pp.215-231
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• 2004

The purpose of this study was to examine what factors affected patients who suffered from essential hypertension compliance with health behaviors, to help build a successful strategy to step up their compliance with health behaviors, and to seek effective ways to implement health education programs for patients with chronic disease. The subjects in this study were 60 people selected from among the patients who were diagnosed by physicians as having essential hypertension in S General Hospital in the city of P from April 10 through July 30, 2000, after health education was provided four times a month. The quasi- experimental design based on a control group pretest-posttest design was employed. The subjects were divided into three groups of 20 patients each： one was an experimental group to receive education in one-to-one interview, another was an experimental group to receive education as a group, and the third was a control group. The two experimental groups learned the same material through different methods, and the control group was given the same teaching materials and asked to comply with health behaviors on their own without instruction. After the three-week education was implemented in different ways, their compliance with health behaviors was measured. Collected data was analyzed by t-test, paired test, one-way analysis of variance, correlation analysis and regression analysis procedures. The findings of this study were as follows： 1. Concerning the effective type of health education, the group education produced the best results, followed by the one-to-one interviews and the sole use of print media. 2. Regarding the effect of compliance with health behaviors, the group- educated group got the highest score in compliance with health behaviors, but blood pressure lowered more significantly in the individual interview group. And the compliance with health behaviors had a significant negative correlational relationship with both systolic and diastolic blood pressure. 3. Parameter that had most significant correlational relationship with compliance with health behaviors was health locus of control, followed by self-efficacy and health perception. But there was no significant correlational relationship between compliance with health behaviors and knowledge of hypertension. 4. As a result of analyzing the impact of knowledge of hypertension, health locus of control, self-efficacy and health perception on compliance with health behaviors, self-efficacy was found to exercise most influence. Above-mentioned findings suggested that group education or one- to-one discussion would be more effective for health care for hypertension in koreans, as they could serve to have patients realize their own responsibility for health and to motivate their compliance with health behaviors, and there was a need to more positively utilize educational intervention for patients with chronic diseases, which could elevate not only compliance with health behaviors but self-efficacy.

• Journal of Digital Convergence
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• v.18 no.9
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• pp.441-451
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• 2020

The study was conducted with the aim of identifying the impact of competition anxiety on dance immersion and performance in high school students majoring in dance. As of 2020, online surveys were conducted on students majoring in dance at high schools in Seoul and the metropolitan area. A total of 222 people's data were processed by applying t-test, one-way variable analysis, correlation and multiple regression analysis through SPS 18.0 for Windows, resulting in the following conclusions. First, male students were more confident in their condition than female students, and students who recognized that their family's economic power was in the middle class were more aware. In addition, it was found that the group perceived that economic power was at the top of the list was higher than the median. Second, cognitive anxiety and self-confidence have been shown to have a static effect on immersion into dance. Third, cognitive anxiety and self-confidence have been shown to have a static effect on the achievement of uselessness. Fourth, immersion in dance appeared to be a powerful parameter related to competition anxiety and achievement of dance. To sum up the above conclusions, competition among high school students majoring in dance has been shown to increase their performance by immersing themselves in dance, but further studies of these psychological variables are expected to have side effects.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.521-528
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• 2017

In this study, vertical loading tests were conducted to investigate the nonlinear behaviors of the fastening systems that have generally been used in the concrete track of domestic railway lines. Nonlinear load-displacement curve models were derived based on the test results. The uplift forces generated in the fastening systems were evaluated by applying the derived nonlinear models as well as the existing linear models. The influence of the factors on the maximum uplift force of the fastening system was analyzed through a parameter study on the distance between neighboring sleepers, the horizontal distance between the center of the bearing and the nearest fastening system from the deck end, and the height of the bridge girder. From the evaluation results it is known that, for economical track and bridge design, due to deck end deformation, it is necessary to consider the nonlinear behavior of the fastening system in the calculation of the uplift force of the fastening systems.

• Journal of Korea Water Resources Association
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• v.46 no.11
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• pp.1053-1067
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• 2013

Distributed ecohydrological model which can simulate hydrological components, vegetation and landsurface temperature using practically available input and observed data with minimum parameters is introduced. This model is designed to properly simulate in area with lack of observed data. Parameter estimation and calibration of the model can be carried out with indirectly estimated data (monthly surface runoff by NRCS-CN method and annual actual vaporization by empirical equation) and remote sensing data (NDVI, LST) instead of observed data. We applied this model in the Naeseong creek basin to evaluate the model validity. Firstly, we found the sensitive parameters which largely influence the simulation results by sensitivity analysis, and then hydrological components, vegetation, land-surface temperature, routed streamflow and water temperature were simulated over 10 years (2001 to 2010) using calibrated parameters. Parameters are estimated by optimization method. It is shown that most of grids are well simulated. In the case of streamflow and water temperature, we checked two observed points in the outlet of watershed and it is shown that streamflow and water temperature are properly simulated as well. Hence, it can be shown that this model properly simulate the hydrological components, vegetation, land-surface temperature, routed streamflow and water temperature as well, even though in despite of using limited input data and minimum parameters.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1077-1080
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• 2008

Material parameters such as surface chloride content, water permeability coefficient, chloride diffusivity and critical chloride content are a substantial key parameter for understanding the durability performance of concrete and its micro-structural densification. Over the past few decades, a considerable number of studies on the durability design for marine concrete structures have been carried out. However, the results are different to each other. In order to establish a consistent durability design system of concrete, it is a precondition to define material parameters, which affect deterioration of concrete due to chloride penetration. Such parameters are surface chloride content, chloride diffusivity, and critical chloride content. Usually these parameters are assumed as temporary constant values or obtained from the experimental results for short term. However, it is necessary to define these parameters reasonably, because these significantly influence the calculation of service life of concrete. In this paper, it is introduced to define material parameters of concrete for chloride diffusion, such as surface chloride content $[Cl]_s$, water permeability coefficient K, chloride diffusivity $D_{Cl}$, critical chloride content $[Cl]_{cr}$. These are expressed as time function considering hydration evolution of hardened cement paste. The definition of the material parameters is a prerequisite to simulate chloride penetration into concrete as time elapsed.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.6
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• pp.651-656
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• 2014

Corrosion has a significant influence upon the reliability assessment and the maintenance planning of gas pipeline. Corrosion defects occurred on the underground pipeline can be obtained by conducting periodic in-line inspection (ILI). However, little study has been done for practical use of ILI data. This paper deals with remaining lifetime prediction of the gas pipeline in the presence of corrosion defects. Because a pipeline parameter includes uncertainty in its operation, a probabilistic approach is adopted in this paper. A pipeline fails when its operating pressure is larger than the pipe failure pressure. In order to estimate the failure probability, this paper uses First Order Reliability Method (FORM) which is popular in the field of structural engineering. A well-known Battelle code is chosen as the computational model for the pipe failure pressure. This paper develops a Matlab GUI for illustrating failure probability predictions Our result indicates that clustering of corrosion defects is helpful for improving a prediction accuracy and preventing an unnecessary maintenance.

• Geotechnical Engineering
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• v.3 no.4
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• pp.41-54
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• 1987

A stochastic numerical analysis for predicting the groundswater fluctuations in hillside slopes is performed in this paper to account for the uncertainties associated with the rainfall and site characteristics. The effect of spatial variabilities of aquifer parameters and the effect of temporal variability of recharge on the groundwater fluctuations are studied in depth. The Kriging is used to account for the spatial tariabilities of aquifer parameters. This technique prolevides the best linear unbiased estimator of a parameter and its minimum variance from a litsitem number of measured data. A stochastic one-dimensional numerical model is delreloped b) combining the groundwater flow model, the Kriging, and the first-order second-moment analysis. In addition, a two dimensional detelministic groundwater model is developed to study the change of ground water surfas in the transverse direction as well as in the downslope direction. It is revealed that the undulations of the impervious bedrock in addition to the permeability and the specific yield have an important influence on the fluctuations of the groundwater surface. It is also found that th'e groundwater changes significantly in the transverse direction as well as in the downslope direction. The results obtained in this analysis may be used for evaluation of landslide risks due to high porewater pressure.