• 대한안전경영과학회지
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• 제13권1호
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• pp.107-114
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• 2011

Location-Based Service(LBS) is a service that provides a variety of convenience in life using location information that can be obtained by mobile communication network or satellite signal. In order to provide LBS precisely and efficiently, we need the location determination technology, platform technology and server technology. In this study, we studied on how we can reduce the error on location determination of objects such people and things. Fingerprint location determination method was applied to this study because it can be used at current wireless communication infrastructure and less influenced by a variety of noisy environment than other location determination methods. We converted the probability value to logarithmic scale value because using the sum of k probability values is not suitable to be applied to weight determination. In order to confirm the performance of suggested method, we developed location determination test program with Visual Basic 6.0 and performed the test. According to indoor and outdoor test results, the suggested stochastic method reduced the distance error by 17%, 18% and 9% respectively at indoor environment and 25%, 11% and 4% at outdoor environment compared with deterministic NN, kNN and kWNN fingerprint methods.

• 한국군사과학기술학회지
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• 제9권3호
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• pp.88-94
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• 2006

In order to substitute current aluminum sabot and to increase the penetration performance of the kinetic energy projectiles, the research and development program for composites sabot has been conducted. For carbon/epoxy composites sabot, unidirectional carbon fiber reinforced epoxy prepreg was chosen and thick sectioned composites preforms with the different fiber angles along the circumferential direction of sabot were prepared by compression molding under the careful processing conditions at $150^{\circ}C$ for 1hour with $70kgf/cm^2$ curing pressure. The composites sabot demonstrated a weight reduction by approximately 30% than that of current aluminum sabot. The muzzle velocity of a kinetic energy projectile with composites sabot was measured to be about 63m/s higher than that with aluminum sabot. These results imply that the penetration performance is expected to be considerably increased when the composite sabot is applied to the kinetic energy projectiles.

• 한국강구조학회 논문집
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• 제9권1호통권30호
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• pp.65-79
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• 1997

Composite materials are consist of two or more different materials to produce desirable properties for structural strength. Because of their superiority in strength, corrosion resistance, and weight reduction, they are used extensively as structural members. The objective of this study is to present the effectivness of the laminated composite elements by analyzing in-plane displacement and stress of the anisotropic laminated annular elements. Anisotropic laminated structures are very difficult to analyze and apply, compared with isotropic and orthotropic cases for arbitrary boundaries and fiber angle -ply. Boundary conditions for the examples used in this study consist of two opposite edges clamped and the other two edges free, and finite difference method is used in this study for numerical analysis. From the numerical result, it is found that the program used in this study can be used to obtain the displacement of the straight beams considering it's transverse shear deformation as well as anisotropic laminated elements. Several numerical examples show the advantages of the stiffness increase when the angle-ply composite materials are used. Therefore it gives a guide in deciding how to make use of fiber's angle for the subtended angle, load cases, and boundary conditions.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.694-699
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• 2002

In autobody assembly, thin-wall, tubular connections have been used for the frame structure. Recent interest in light materials, such as aluminum or magnesium alloys, has been rapidly growing for weight reduction and fuel efficiency. Due to higher thermal expansion coefficient, low stiffness/strength, and low softening temperature of aluminum and magnesium alloys, control of welding-induced distortion in these connections becomes a critical issue. In this study, the material sensitivity to welding distortion was investigated using a T-tubular connection of three types materials; low carbon steel (A500 Gr. A), aluminum alloy (5456-H116) and magnesium alloy (AZ91C-T6). An uncoupled thermal and mechanical finite element analysis scheme using the ABAQUS software program was developed to model and simulate the welding process, welding procedure and material behaviors. The predicted angular distortions were correlated to the cumulative plastic strains. A unique relationship between distortion and plastic strains exists for all three materials studied. The amount of distortion is proportional to the magnitude and distribution of the cumulative plastic strains in the weldment. The magnesium alloy has the highest distortion sensitivity, followed by the other two materials with the steel connection having the least distortion. Results from studies of thin-aluminum plates show that welding distortion can be minimized by reducing the cumulative plastic strains by preventing heat diffusion into the base metal using a strong heat sink placed directly beneath the weld. A rapid cooling method is recommended to reduce welding distortion of magnesium tubular connections.

• 기본간호학회지
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• 제17권4호
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• pp.557-565
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• 2010

Purpose: This study was conducted to investigate the factors influencing the quality of life among the patients with Crohn's disease. Method: Data were collected from 97 Crohn's disease patients between September 17 and October 20 in 2009. The collected data were analyzed by SPSS program. Results: There were significant differences in the participants' quality of life depending on their age, economic status, pain, diarrhea, weight loss, Crohn's disease activity index (CDAI), and use of medications such as antidiarrhotica, steroid, and analgesics. The results also showed the correlations between the participants' qualities of life and thier pain, CDAI, anxiety, depression, perceived health condition, and of body image. Finally, the factors affecting the quality of life in patients with Crohn's disease included anxiety, perceived health state, pain, and CDAI. The explanatory power of these factors was 79.5%. Conclusion: The results imply that controlling the patients' pain and providing emotional support for anxiety reduction are crucial. In a similar vein, tailored nursing interventions considering individual patients' conditions are believed to help the patients positively perceive their disease. A future research, can conduct further investigations of these factors from more diverse perspectives, which is expected to promote more effective nursing strategies for Crohn's disease patients.

• Steel and Composite Structures
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• 제37권1호
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• pp.1-14
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• 2020

Composite beams with corrugated steel webs represent a new innovative system which has emerged in the past decade for medium span in the construction technology. The use of composite beams with corrugated steel webs results in a range of benefits, including flexible spaces and reduced foundation costs in the construction technology. The thin corrugated web affords a significant weight reduction of these beams, compared with hot-rolled or welded ones. In the current research, an optimal designed I-girder beam with corrugated web has been proposed to improve the structural performance of continuous composite girder under bending moment. The experimental program has been conducted for six simply supported composite beams with different loading conditions. The tested specimens are designed by using one of the stochastic techniques called hunting search algorithm. In the optimization process, besides the thickness of concrete slab and studs, corrugated web properties are considered as design variables. The design constraints are respectively implemented from Eurocode 3, BS-8110 and DIN 18-800 Teil-1. The last part of the study focuses on performing a numerical study on composite beams by utilizing finite element analysis and the bending behavior of steel girders with corrugated webs experimentally and numerically verified the results. A nonlinear analysis was carried out using the finite element software ANSYS on the composite beams which were modelled using the elements ten-node high order quadrilateral type.

• Structural Engineering and Mechanics
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• 제78권2호
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• pp.135-143
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• 2021

In this study, continuous contact problem in the functionally graded (FG) layer loaded with a FG flat punch resting on the elastic semi-infinite plane was analyzed by the finite element method (FEM). It was assumed that the shear modulus and density of the layer and punch varied according to exponentially throughout their depth. FG layer's weight was included to the problem and additionally all surfaces were considered as frictionless. Analysis of FG materials was performed with a special macro which was added to the ANSYS program. Firstly, the shear modulus of the punch was considered to be very rigid and the results of initial separation load (λcr) and distance (xcr) were compared with the analytical solution. Afterwards, results obtained from the contact analysis made according to the inhomogeneity parameters (β, γ) between FG punch-FG layer which had been unprecedented in the literature were discussed. As a result, FG punch's stress values at the punch edges where stress accumulations occurred were found to be smaller than the rigid punch. The security of the structure, longer life of the material and ease of production are directly related to the reduction of the stress values. The results obtained in this study are important in this respect. Also this work is the first study that investigates the effect of FG punch on the FG layer.

• 한국기계기술학회지
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• 제20권6호
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• pp.947-956
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• 2018

This research has been conducted to design upright parts of hand-made vehicles with the purpose of reducing material and machining cost while ensuring structural safety. Aluminum knuckles were modelled with three parts in order to enhance design flexibility as well as to reduce CNC machining cost. A vehicle model was constructed in CAD program and simulated in ADAMS View in order to estimate joint forces developing during 20 degree step steering condition at 60km/h. The joint forces obtained in the vehicle dynamics simulation were used for the structural analysis in ANSYS and dimensions of knuckle parts were adjusted until the lowest safety factor reached 2.0. The weight of knuckle decreased by 50% compared to the previous version that was designed without the structural analysis. The overall manufacturing cost decreased by 33% due to the reduction in the material as well as the CNC machining effort.

• International Journal of Computer Science & Network Security
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• 제22권2호
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• pp.232-240
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• 2022

To fulfill user expectations, the rapid evolution of software techniques and approaches has necessitated reliable and flawless software operations. Aging prediction in the software under operation is becoming a basic and unavoidable requirement for ensuring the systems' availability, reliability, and operations. In this paper, an improved evolutionary computing-driven extreme learning scheme (ECD-ELM) has been suggested for object-oriented software aging prediction. To perform aging prediction, we employed a variety of metrics, including program size, McCube complexity metrics, Halstead metrics, runtime failure event metrics, and some unique aging-related metrics (ARM). In our suggested paradigm, extracting OOP software metrics is done after pre-processing, which includes outlier detection and normalization. This technique improved our proposed system's ability to deal with instances with unbalanced biases and metrics. Further, different dimensional reduction and feature selection algorithms such as principal component analysis (PCA), linear discriminant analysis (LDA), and T-Test analysis have been applied. We have suggested a single hidden layer multi-feed forward neural network (SL-MFNN) based ELM, where an adaptive genetic algorithm (AGA) has been applied to estimate the weight and bias parameters for ELM learning. Unlike the traditional neural networks model, the implementation of GA-based ELM with LDA feature selection has outperformed other aging prediction approaches in terms of prediction accuracy, precision, recall, and F-measure. The results affirm that the implementation of outlier detection, normalization of imbalanced metrics, LDA-based feature selection, and GA-based ELM can be the reliable solution for object-oriented software aging prediction.

• 기본간호학회지
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• 제11권2호
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• pp.203-212
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• 2004

Purpose: This study was done to determine whether providing auditory and vestibular stimulation to preform infants would have an effect on stress hormones. Methods: The design was a nonequivalent control group protest-posttest design in a quasi-experimental study Seventy-nine preform infants were assigned either one of two experimental groups or to a control group: 27 in the auditory stimulation group, 25 in the vestibular stimulation group and 27 in the control group. The criteria for inclusion in this study were 1) gestational age of less than 37 weeks, 2) birth weight of less than 2,500g, 3) the absence of congenital anomalies or specific diseases, 4) recovering physiological weight loss, and 5) weaned from ventilatory assistance or oxygen. The data were collected from March 2002 to May 2003. The auditory stimulation, a music audiotape, was provided 20 minutes twice a day for 10 days and the vestibular stimulation, an infant waterbed, was provided for 10 days. On day 1 and day 10 of the study, 24 hour urine sample was collected for norepinephrine, epinephrine, and cortisol assays. In the data analysis SPSSWIN 10.0 program was utilized for descriptive statistics, ANOVA and t-test. Results: General characteristics of the three groups showed no significant differences, thus three groups were found to be homogenous. The 24 hour urine cortisol for the auditory (t=3.489, p=.001) and for the vestibular (t=2.638, p=.013) stimulation group were significantly reduced compared to the control group after 10 days. Conclusions: The results suggest that auditory and vestibular stimulation can be used to reduce 24 hour urine cortisol in preform infants. Therefore, music audiotapes and waterbeds provided in incubator are be recommended for reduction of the stress in preform infants who are hospitalized in neonatal intensive care units.