• Coupled systems mechanics
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• v.4 no.2
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• pp.115-136
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• 2015

We present for one-dimensional model for elastoplastic bar with combined hardening in FPZ - fracture process zone and softening with embedded strong discontinuities. The simplified version of the model without FPZ is directly compared and validated against analytical solution of Bazant and Belytschko (1985). It is shown that deformation localizes in an area which is governed by the chosen element size and therefore causes mesh sensitivity and that the length of the strain-softening region tends to localize into a point, which also agrees with results obtained by stability analysis for static case. Strain increases in the softening domain with a simultaneous decrease of stress. The problem unloads elastically outside the strain-softening region. The more general case with FPZ leads to more interesting results that also account for induced strain heterogeneities.

• Journal of the Korea Society for Simulation
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• v.1 no.1
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• pp.1-16
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• 1992

This research develops two variance reduction methods for estimating the parameters of the experimental simulation model having multiple design points based on an approach focusing on reduction of the variances of the mean responses across multiple design points. The first method extends a combined approach of antithetic variates and control variates for a single design point to the multipopulation context with independent streams across the design points. The second method extends the same strategy in conjunction with the Schruben-Margolin method for improving the first method. We illustrate an example for implementing the second method. We expect these two approaches may improve the estimation of the parameters of interest compared with the control variates method.

• Journal of the Optical Society of Korea
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• v.14 no.1
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• pp.55-62
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• 2010

We introduce a new method for lens design that combines an eyepiece with the finite model eye, to make a corrected version of the accommodation-dependent Navarro eye. The optical system that we designed, which includes a human eye, takes into account the aberration of the eye and increases the performance of the image in the retina. In the design results, for the optimized eyepiece combined with the corrected Navarro eye, visual acuity is 1.40. Compared with the existing method of eyepiece design using inverse ray tracing with the corrected Navarro eye, MTF value was recorded as 0.079 to 0.283 at 160 lp/mm and visual performance was improved.

• ETRI Journal
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• v.44 no.4
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• pp.624-640
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• 2022

Taxi-demand forecasting and hotspot prediction can be critical in reducing response times and designing a cost effective online taxi-booking model. Taxi demand in a region can be predicted by considering the past demand accumulated in that region over a span of time. However, other covariates-like neighborhood influence, sociodemographic parameters, and point-of-interest data-may also influence the spatiotemporal variation of demand. To study the effects of these covariates, in this paper, we propose three models that consider different covariates in order to select a set of independent variables. These models predict taxi demand in spatial units for a given temporal resolution using linear and ensemble regression. We eventually combine the characteristics (covariates) of each of these models to propose a robust forecasting framework which we call the combined covariates model (CCM). Experimental results show that the CCM performs better than the other models proposed in this paper.

• International journal of advanced smart convergence
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• v.11 no.2
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• pp.77-82
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• 2022

The third-person side view game perspective of side-scrolling games makes playing such games a completely different gaming experience from other traditional games. Nowadays, many game elements are combined with each other, and horror and puzzle elements are often combined to appear in side-scrolling games, bringing players a unique gaming experience. In such games, players seem to be watching their own manipulation of characters. The performance is the same as a stage play, so how to let players better experience such a horror and puzzle-solving stage play through the design of the characters is a key point. However, it is often difficult to accurately classify only from game elements, so first of all, the author will explain the game division of the side scrolling horror puzzle game. After that, this article will analyze the character designs in the three works with high sales and good reputation on Steam, and then draw conclusions.

• Journal of Korean Port Research
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• v.8 no.2
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• pp.67-77
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• 1994

A time-domain numerical model is developed to examine the performance of a wave energy focusing structure in combined waves and a current. With the current assumed to be slow and the structure fully submerged, the wave-current interaction problem is reduced to a wave scattering problem in a uniform current. The diffraction of incident waves around a narrow berm is considered. The shape of the berm is defined by a parabola, imitating that of an optical reflector. The energy focus is achieved by reflecting the incident waves through a predetermined focal point. Through the numerical simulations, the numerical model is shown to be effective in modeling the wave-current interaction problem, and the current speed and direction are shown to affect significantly the location, amplitude and sharpness of the focus.

• Water Engineering Research
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• v.3 no.2
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• pp.85-92
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• 2002

There has been continuous efforts to manage water resources for the required water quality criterion at river channel in Korea. However, we could obtain the partial improvement only for the point sources such as, waste waters from urban and factory site through the water quality management. Therefore, it is strongly needed that the best management practice throughout the river basin fur water quality management including non-point sources pollutant loads. This problem should be resolved by recognizing the non-point sources pollutant loads from the upstream river basin to the outlet of the basin depends on the landuse and soil type characteristics of the river basin using the computer simulation by a distributed model based on the detailed investigation and application of Geographic Information System (GIS). The purpose of this study is consisted of the three major distributions, which are the investigation of spread non-point sources pollutants throughout the river basin, development of the base maps to represent and interpret the input and outputs of the distributed simulation model, and prediction of non-point sources pollutant loads at the outlet of a up-stream river basin using Agricultural Non-Point Sources Model (AGNPS). For the validation purpose, the Seom-Jin River basin was selected with two flood events in 1998. The results of this application showed that the use of combined a distributed model and an application of GIS was very effective fur the best water resources and quality management practice throughout the river basin

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.1 s.19
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• pp.83-90
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• 2002

Control point survey by GPS can save labor and time and can obtain result of high accuracy, but if excessive error is contained to Control point that is used to GPS relative positioning, the error that has influence on new point is propagated to various configuration. therefore poor triangulation points that are caused by careless management are existed, a product of the triangulation points still are in many case. In order to select new point, this study carried out error-analysis of surrounding-control-points and performed selective process of control point. The propriety parts of control points that are used to verify precision is identified by means of comparing existing product with or GPS product about some control points after directly observe each baseline by using EDM. As the error is analyzed by static positioning the optimum control point is selected, the precision of survey data by EDM is improved than GPS data.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.10
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• pp.36-42
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• 2010

FFT(Fast Fourier Transform) processor is one of the key components in the implementation of OFDM systems for many wireless standards such as IEEE 802.22. To improve the performances of FFT processors, various studies have been carried out to reduce the complexities of multipliers, memory interface, control schemes and so on. While the number of FFT stages increases logarithmically $log_2N$) as the FFT point-size (N) increases, the number of required registers (or, memories) increases linearly. In large point-size FFT designs, the registers occupy more than 70% of the chip area. In this paper, to reduce the memory size of IFFT for OFDM transmitters, we propose a new IFFT design method based on a combined mapping of modulated data, pilot and null signals. The proposed method focuses on reducing the sizes of the registers in the first two stages of the IFFT architectures since the first two stages require 75% of the total registers. By simulations of 2048-point IFFT design for cognitive radio systems, it is shown that the proposed IFFT design method achieves more than 38.5% area reduction compared with previous IFFT designs.

• Korean Journal of Acupuncture
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• v.37 no.1
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• pp.14-23
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• 2020

Objectives : We investigated the efficacy and safety of miniscalpel acupuncture (MA) treatment combined with non-steroidal anti-inflammatory drugs (NSAIDs) for chronic neck pain (CNP) in an assessor-blinded randomized controlled pilot trial to establish a basis for larger-scale randomized controlled studies on this subject. Methods : Participants (n=36) were recruited and randomly allocated to the MA group, NSAIDs and combined treatment group. The MA group received MA three times over three weeks. The NSAIDs group was administered orally with zaltoprofen 80mg t.i.d. over three weeks. The combined treatment group received MA and zaltoprofen in the same manner as MA and NSAIDs groups. The primary outcome was pain as assessed by a visual analogue scale (VAS) and the secondary outcomes were assessed using the Neck Disability index (NDI), EuroQol 5-dimension questionnaire (EQ-5D), and Patients' Global Impression of Change scale (PGIC). Assessments were made at week 0 (baseline), 1, 2, 3 (primary end point) during treatment and at week 7 (4 weeks after the end of treatment). Results : 35 participants completed the study. No serious adverse event occurred and blood test results were within normal limits. The improvement of VAS and NDI was significantly greater in combined and MA group than that in NSAIDs group (p<0.017). The combined group showed better outcomes in EQ-5D at visit 2 and 5, in PGIC at visit 4 than the NSAIDs group (p<0.017). No significant differences were found between combined and MA group. Conclusions : Our results suggest that both combined and MA group can be more effective in improving pain control than NSAIDs group. A large-scale clinical study is warranted to further clarify these findings.