• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.321-322
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• 2006

In many manufacturing processes such as web formation, manufacturing of paper and nonwoven, fabric weaving, etc., planar sheets are transported and at the same time appropriate tension is imposed. The input material rolled up on beams is fed by unwinding the beam and the processed is then taken up on beams by winding it. While processed, the planar sheets are thrown under the processing load of impulse form, which causes irregular thickness of the processed sheet. To improve the quality of the product, a dynamic model is needed and the dynamic characteristics is to be analyzed by simulation. This study shows that density variation dynamics of the in-process-sheet in the machine direction can be described at each moment of disturbing impacts in forms of difference equations, while the impacts and tension, the time-dependency of the material properties were taken into account. Simulation showed the most serious variation of the density occurred in the process starting phase. The starting velocity curve with step form showed the least variation of the density. As the time order of the function of the starting velocity cure becomes higher, the density variation gets greater.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.2
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• pp.63-73
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• 2011

The Pseudorange Corrections (PRC), which are used in DGPS as calibration messages, can contain outliers, noise, and anomalies, and these abnormal events are unpredictable. When those irregular PRC are used, the positioning error gets higher. In this paper, we propose a strategy of detecting and correcting outliers, noise, and anomalies by modeling the changing pattern of PRC through polynomial curve fitting techniques. To validate our strategy, we compared positioning errors obtained without PRC calibation with those with PRC calibration. As a result, we found that our algorithm performs very well; the horizontal RMS error was 3.84 m before the correction and 1.49 m after the correction.

• Spatial Information Research
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• v.11 no.2
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• pp.143-153
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• 2003

In order to investigate the effect of a pouring rain that it follows in the typhoon, the effect analysis with actual measurement data of rainfall outflow it follows in flood basin is necessary. Also there is a case that it analyzes with the fact that the rainfall occurs identically in whole basin in case of the rainfall outflow analysis, but the actual rainfall distribution from the basin very will be irregular and the interpretation which it reflects must become accomplished. It created spatial information of terrain, land use and the soil using GIS. It created topographical factor of the subject area and calculated CN(runoff curve number) with WMS(Watershed Modeling System). It calculated runoff using a HEC-1 model and the Rational Method connected at the WMS. By connecting GIS and WMS, it calculated the effect of a pouring rain and runoff from the construction area. Also it will be able to apply with a basic data in more efficient runoff analysis.

• Journal of Ocean Engineering and Technology
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• v.29 no.2
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• pp.191-198
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• 2015

In this study, we proposed a new type of dual-buoy wave energy converter (WEC) exploiting multi-resonance and analyzed the experimental results from a model test in a 2-D wave flume. A dual-buoy WEC using multi-resonance has two advantages: high efficiency at the resonant frequencies and the potential to extend the frequency range available to extract wave power from the WEC. The suggested WEC was composed of an outer buoy and an inner buoy sliding vertically inside the outer buoy. As the power take-off device, a linear electric generator (LEG) consisting of permanent magnets and coils fixed at each buoy was adopted. Electricity was produced by the relative heave motion between the two buoys. To search for the optimal shape of a dual-buoy WEC, we conducted experiments on the heave motion of a two-body system in regular waves without an LEG installed. Model tests with six combinations of experimental models were conducted in order to find the motion characteristics of a dual-buoy WEC. It was found that model 2, which included a ring-shaped appendage to move the resonant frequency of the outer buoy toward a high value, showed a higher relative heave response amplitude operator (RAO) curve than model 1. In addition, the double-peak shape of the heave RAO curve shown for model 2 indicated the extension of the frequency range for extracting wave power in irregular waves.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.46.3-47
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• 2020

Variations in the brightness of asteroids are caused by their spins, irregular shapes and companions. Thus, in principle, the spin state and shape model of a single object or, a combined model of spins, shapes and mutual orbit of a multiple components can be constructed from the analysis of light curves obtained from the time-series photometry. Using ground- and space-based facilities, a number of time-series photometric observations of asteroids have been conducted to find the possible causes of their light variations. Nonetheless, only about 2% of the known asteroids have been confirmed for their rotation periods. Therefore, a follow-on systematic photometric survey of asteroids is essential. We started an asteroid light curve survey for this purpose using Korea Microlensing Telescope Network (KMTNet) during 199 nights between the second half of 2019 and the first half of 2020. We monitored within a 2° × 14° region of the sky per each night with 25 min cadences. In order to observe as many asteroids as possible with a single exposure, we mostly focus on the ecliptic plane. In our survey, 25,925 asteroids were observed and about 8,000 of them were confirmed for their rotation periods. In addition, using KMTNet's 24-hour continuous monitoring, we collected many composite light curves of slow rotating asteroids that were rarely obtained with previous observations. In this presentation, we will introduce the typical light curves of asteroids obtained from our survey and present a statistical analysis of spin states and shapes of the asteroids from this study.

• Journal of Korea Water Resources Association
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• v.46 no.6
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• pp.597-611
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• 2013

This paper presents the methodology for construction of time-area curve via the width function and thereby rational estimation of time of concentration and storage coefficient of Clark model within the framework of method of moments. To this end time-area curve is built by rescaling the grid-based width function under the assumption of pure translation and then the analytical expressions for two parameters of Clark model are proposed in terms of method of moments. The methodology in this study based on the analytical expressions mentioned before is compared with both (1) the traditional optimization method of Clark model provided by HEC-1 in which the symmetric time-area curve is used and the difference between observed and simulated hydrographs is minimized (2) and the same optimization method but replacing time-area curve with rescaled width function in respect of peak discharge and time to peak of simulated direct runoff hydrographs and their efficiency coefficient relative to the observed ones. The following points are worth of emphasizing: (1) The optimization method by HEC-1 with rescaled width function among others results in the parameters well reflecting the observed runoff hydrograph with respect to peak discharge coordinates and coefficient of efficiency; (2) For the better application of Clark model it is recommended to use the time-area curve capable of accounting for irregular drainage structure of a river basin such as rescaled width function instead of symmetric time-area curve by HEC-1; (3) Moment-based methodology with rescaled width function developed in this study also gives rise to satisfactory simulation results in terms of peak discharge coordinates and coefficient of efficiency. Especially the mean velocities estimated from this method, characterizing the translation effect of time-area curve, are well consistent with the field surveying results for the points of interest in this study; (4) It is confirmed that the moment-based methodology could be an effective tool for quantitative assessment of translation and storage effects of natural river basin; (5) The runoff hydrographs simulated by the moment-based methodology tend to be more right skewed relative to the observed ones and have lower peaks. It is inferred that this is due to consideration of only one mean velocity in the parameter estimation. Further research is required to combine the hydrodynamic heterogeneity between hillslope and channel network into the construction of time-area curve.

• The Research Journal of the Costume Culture
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• v.16 no.5
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• pp.924-936
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• 2008

The purpose of this thesis is to discuss corsets that represent an undergarment that later became a popular outerwear. It discusses its forms and distinct characteristics to help create a unique fashion design and its execution. The scope of this study is limited to works from the 1990s to the present, and the materials for the literatures and exploratory study are fashion-related portfolios and the domestic and foreign fashion magazines. The results of this study are summarized as follows: The standard look of corsets in modern fashion can be classified into styles of glamour, revival, and dismantle. The materials used vary from traditional fabrics such as satin or lace to newly developed materials such as metal or glass. Its presentation can also differ in that it may be used as an accessory with additional details, as an outerwear, as an extra decorative layer, or as a revealing innerwear by open outerwear. Characteristics of these various looks of corsets are; first, it redefines the revival of the traditional corsets through introduction of its historic elements and its compromise. Second, glamorous and feminine images are maximized through drastic and direct exposure by using tight lacing, a waist nipper or garter belts that emphasize a woman's curve. Third, it represents borderless dismantlement through experimental and irregular images using unconventional materials, new execution techniques, or alteration from the standard forms.

• The Research Journal of the Costume Culture
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• v.17 no.3
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• pp.396-406
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• 2009

Drapery costume started with using one fabric to loosely wrap around one's body without using technical skills or needlework. Drapery becomes a beautiful and indeterminate form of pleated costume which determines the costume silhouette and serves as an essential component for the composition of artistic costume. The purpose of this study was to examine the aesthetic characteristics of drapery costume using literature review. The study methods include considerations of the formation process of drapery costume with the analysis of costume in pictures. For modern costume designs, the study analyzed the designer's dress with a focus on drapery forms, which appeared in the collections from 2001 to 2007. First, drapery costume contains the beauty of human body. Drapery costume reveals the smallest movement of the body. The beauty of drapes, which is naturally revealed along the curve of the body, and the pleats which form on the soft cloth create the beauty of body. Second, drapery costume has rhythmical beauty. Drapery pleats feature not only functions, but also unique formativeness that provides rhythmicity and regular or irregular direction effects by line. Third, drapery costume features elegant beauty. Bias cutting by draping can effectively express the elegant characteristics of the fabric. In making a piece of clothing, the composition method can express elegant beauty by covering up the shortcomings of the fitting and by fitting to the body line without cutting the fabric, or fitting it by bias cutting.

• Journal of the Korea Concrete Institute
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• v.12 no.2
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• pp.63-69
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• 2000

This study investigates a new method of using a concrete disk to calculate stress intensity factor (SIF) for mixed mode cases. The results indicate that the disk method is more accurate than three point bending test (TPB) in obtaining correct SIF values for mixed mode fracture propagation. Stress intensity factors $K_{I}$ and $K_{II}$ are calculated using a center notched disk subjected to splitting load. The notch angle is calculated by finite element (FEM). Fracture toughness $K_\textsc{k}$ of the concrete is obtained from the load intensities at the initiation of crack propagation. According to the finite element analysis(FEA) and disk test, the results show that mode I and mixed mode cracks propagate toward the directions of crack face and loading point, respectively. The results from FEA with maximum stress theory compare well with the experimental date. Unlike TPB method where an accurate fracture toughness value is difficult to obtain due to the irregular shape of load deflection curve and delayed final crack propagation (following slow stable cracking). fracture toughness value is easily measured in the disk test from the crack initial load. Therefore, it is safe to conclude that disk method is more advantageous than TPB method in analyzing combined mode fracture problems.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.1 s.139
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• pp.43-49
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• 2005

in this paper a dolphin-fender moored pontoon-type floating structure in shallow water depth is studied focusing on mooring force. The pontoon-type floating structure is 500m long, 300m wide. The structure has partially non-uniform drafts of 2.0m and 3.0m. The employed mooring system is a guyed frame type dolphin-fender system. The 1/125 scale model fender system is made of rubber tube to have hi-linear load deflection characteristics. A series of model tests has been conducted focusing on motion and fender force responses in regular and irregular waves at KRISO's ocean engineering basin Non-linear numerical simulation of fender reaction force has been carried out and the results are compared with those of model tests. The simulated rigid body motion and mooring forces also have been compared with the test results.