• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.843-846
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• 2004

For the fast growing Liquid Crystal Display (LCD) TV market, it is essential to make the LCD panels to show moving images without any visual difficulties such as blurring or tailing. Owing to reduction of the cell gap and the improved Liquid Crystal (LC) mixtures with low viscosity, it is possible that our S-IPS TFT-LCDs feature a response time (R/T) as fast as 1-frame time (16ms) for a white-black operation and less than a 16rns in all gray levels without Over Driving Circuit (ODC) technology. Currently, mass production of the large size IPS panels with high speed has been successfully achieved. In order to achieve faster response time, new LC mixtures have been developed, optimizing the physical properties of rotational viscosity (${\gamma}$1) and elastic constants (Kii). Also, the LC mixtures with high elastic constant allow us to increase the cell gap. In this paper, realization of fast switching time in IPS mode with optimized '${\gamma}$1/Kii' parameter in the LC mixtures forms the core of this paper.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.1-1
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• 2009

In this presentation, I talk about various fluid simulation methods that have been developed for computer graphics special effects since 1996. They are all based on CFD but sacrifice physical reality for visual plausability and time. But as the speed of computer increases rapidly and the capability of GPU (graphics processing unit) improves, methods for more physical realism have been tried. In this talk, I will focus on four aspects of fluid simulation methods for computer graphics: (1) particle level-set methods, (2) particle-based simulation, (3) methods for exact satisfaction of incompressibility constraint, and (4) GPU-based simulation. (1) Particle level-set methods evolve the surface of fluid by means of the zero-level set and a band of massless marker particles on both sides of it. The evolution of the zero-level set captures the surface in an approximate manner and the evolution of marker particles captures the fine details of the surface, and the zero-level set is modified based on the particle positions in each step of evolution. (2) Recently the particle-based Lagrangian approach to fluid simulation gains some popularity, because it automatically respects mass conservation and the difficulty of tracking the surface geometry has been somewhat addressed. (3) Until recently fluid simulation algorithm was dominated by approximate fractional step methods. They split the Navier-Stoke equation into two, so that the first one solves the equation without considering the incompressibility constraint and the second finds the pressure which satisfies the constraint. In this approach, the first step introduces error inevitably, producing numerical diffusion in solution. But recently exact fractional step methods without error have been developed by fluid mechanics scholars), and another method was introduced which satisfies the incompressibility constraint by formulating fluid in terms of vorticity field rather than velocity field (by computer graphics scholars). (4) Finally, I want to mention GPU implementation of fluid simulation, which takes advantage of the fact that discrete fluid equations can be solved in parallel.

• The Journal of Korean Academy of Sensory Integration
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• v.4 no.1
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• pp.1-15
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• 2006

Objective : The purpose of this study was to examine the correlation between handwriting skills and praxis. Method : Participants consisted of 50 normal children who were the second-grade students at an A elementary school in Kim-hae. They didn't have a visual dysfunction, an auditory dysfunction, and a disease or an injury in arms and hands. They could follow examiners' directions properly. They were administered the Postural Praxis and the Praxis on Verbal Command of the Sensory Integration and Praxis Tests(SIPT)(Ayres, 2000) and the handwriting skill test which was made with reference to foreign literatures. It was conducted from October 19, 2004 to December 17, 2004. The data were analyzed with non-paired t-test, ANOVA, and Pearson correlation coefficient. Results : 1. Total handwriting score and praxis according to gender of children showed the statistically significant differences(p<0.05). 2. Total handwriting score correlated with praxis(p<0.05) and handwriting speed did not correlate with praxis. 3. Postural Praxis and Praxis on Verbal Command according to handwriting groups showed the statistically significant differences(p<0.05). 4. Among the standards of the handwriting skill test, accuracy of letter form, identity of letter size, spacing between letters and words, placing text on lines, error existence, and letter out of regular square correlated with the Postural Praxis(p<0.05), and accuracy of letter form, identity of letter size, and placing text on lines correlated with the Praxis on Verbal Command(p<0.05). Conclusions : The correlation between handwriting skills and praxis will help occupational therapists to provide fundamental and various treatment programs for children who are referred for the poor handwriting. But more studies in handwriting skills and praxis are necessary to decide which component of handwriting skills is related to praxis.

• The Korean Journal of Applied Statistics
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• v.22 no.4
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• pp.709-721
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• 2009

This paper discusses an efficient image segmentation using morphological watershed algorithm that is robust to noise. Morphological image segmentation consists of four steps: image simplification, computation of gradient image and watershed algorithm and region merging. Conventional watershed segmentation exhibits a serious weakness for over-segmentation of images. In this paper we present a morphological edge detection methods for detecting edges under noisy condition and apply our watershed algorithm to the resulting gradient images and merge regions using Kolmogorov-Smirnov test for eliminating irrelevant regions in the resulting segmented images. Experimental results are analyzed in both qualitative analysis through visual inspection and quantitative analysis with percentage error as well as computational time needed to segment images. The proposed algorithm can efficiently improve segmentation accuracy and significantly reduce the speed of computational time.

• Korean Institute of Interior Design Journal
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• v.20 no.1
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• pp.3-13
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• 2011

The Korean society is recently becoming the aging society at an unprecedentedly rapid speed. Following the increase of the older population, their needs for special care is also rocketing. However, due to the increase of working women, nuclear-families, and old persons living alone, new facilities for the elderly such as nursing home are urgently needed. Thus, many nursing homes for the elderly are also rapidly providing. It is needed to examine if such nursing homes are properly designed for the dependent elderly to live. This study was carried out by the field observation using a checking sheet with measuring and taking photograph. The subjects were 12 nursing homes which gave positive responses for walking through their facilities. The items for observing and measuring were made based on the regulation on improving the facilities for the disabled, the elderly, and the pregnant. Whether each item fits the regulation or not was examined. The 9 areas in each nursing home were examined : entrance, hallway and corridor, stair, elevator, ramp, bed room, shower and locker room, bathroom, and rest room. It was founded that many accessible-related items were met. However, many supportive-related items such as ones for the visual disabled, and many supportive-related and accessible-related ones for bathroom, shower room, and restroom were unmet. In the process of this research, it was founded that the tool for evaluating the design of nursing home in terms of universal design should be developed.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.701-706
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• 2009

We proposed the device to control a computer with only a head and eye blinks so that disabilities by car accidents can use a computer. Because they have paralysis of their upper extremities such as C4~C5 paraplegics and cerebral palsy, they cannot efficiently access a general keyboard/mouse not using hands and foots. The cursor position was estimated from a gyro-sensor which can measure head movements, and the mouse event such as click/double click from opto-sensors which can detect eye blinks. The sensor was put on the proper goggle in order not to disturb the visual field. The performance of the proposed device was compared to a general optical mouse, and was used both relative and absolute coordinate in cursor positioning control. The recognition rate of click and double-click was 86% of the optical mouse, the speed of cursor movement by the proposed device was not much different from the mouse. The overall accuracy was 80%. Especially, the relative coordinate is more convenience and accuracy than the absolute coordinate, and can reduce the frequency of reset to prevent the accumulative error.

• Journal of Ocean Engineering and Technology
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• v.25 no.6
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• pp.91-96
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• 2011

In this paper, friction welded joints were constructed to investigate the mechanical properties of welded 15-mm diameter solid bars of Mg alloy (AZ31B). The main friction welding parameters were selected to endure reliable quality welds on the basis of visual examination, tensile tests, impact energy test, Vickers hardness surveys of the bonds in the area and heat affected zone (HAZ), and macrostructure investigations. The study reached the following conclusions. The tensile strength of the friction welded materials (271 MPa) was increased to about 100% of the AZ31B base metal (274 MPa) under the condition of a heating time of 1 s. The metal loss increased lineally with an increase in the heating time. The following optimal friction welding conditions were determined: rotating speed (n) = 2000 rpm, heating pressure (HP) = 35 MPa, upsetting pressure (UP) = 70 MPa, heating time (HT) = 1 s, and upsetting time (UT) = 5 s, for a metal loss (Mo) of 10.2 mm. The hardness distribution of the base metal (BM) showed HV55. All of the BM parts showed levels of hardness that were approximately similar to friction welded materials. The weld interface of the friction welded parts was strongly mixed, which showed a well-combined structure of macro-particles without particle growth or any defects. In addition, an acoustic emission (AE) technique was applied to derive the optimum condition for friction welding the Mg alloy nondestructively. The AE count and energy parameters were useful for evaluating the relationship between the tensile strength and AE parameters based on the friction welding conditions.

• Korean Institute of Interior Design Journal
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• v.23 no.5
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• pp.104-111
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• 2014

This study puts its purpose on presenting an integral system of representative urban landscapes, public design and colors, in practicing urban design in the context of local identity. An integral design of public design that successfully plans and executes local identity, and changes recognition of integral management of urban design, is suggested as followings. Firstly, when the catchment area is divided in metropolitan area, it should be reset according to the natural environment condition regardless of administrative area system like city and county. It is the method to classify the metropolitan area by researching and analyzing geographical condition, weather condition, soil and vegetation in detail and subclassify it by the visual commonness of natural environment. Secondly, it is necessary to access the urban landscape, public design and urban color from the overall aspect emphasizing the plan for each field and local identity. They should be practiced by the role and category of each field on the basis of consistent design strategy and instruction but the cooperation system is required as a process to reinforce and specify the mutual limit. Thirdly, the artificial structure is constructed through artificial adjustment depending on the urban formation process and the development time point. Therefore, it is necessary to pay attention to the rapid urban development, the change speed and the landscape formation of each age. It is necessary to classify the type of artificial landscape by age and form similarity and separate the area that should be generalized and controlled by entire metropolitan area form the area that should be specialized by basic local government.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.102-106
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• 2016

With the popularity of smart phones and the help of high-speed wireless communication technology, high-quality multimedia contents have become common in mobile devices. Especially, the release of Oculus Rift opens a new era of virtual reality technology in consumer market. At the same time, 3D audio technology which is currently used to make computer games more realistic will soon be applied to the next generation of mobile phone and expected to offer a more expansive experience than its visual counterpart. This paper surveys concepts, algorithms, and systems for modeling 3D sound virtual environment applications. To do this, we first introduce an important design principle for audio rendering based on physics-based geometric algorithms and multichannel technologies, and introduce an audio rendering pipeline to a scene graph-based virtual reality system and a hardware architecture to model sound propagation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.45-56
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• 2007

Automatic tracking of vehicles is important to accurately estimate the traffic information including vehicle speeds in video-based traffic measurement systems. Because of the limited field of view, the range of visual tracking with a single camera is restricted. In order to enlarge the tracking range for better chance of monitoring the vehicle behaviors, a tracking with consecutive multiple video sequences is necessary. This parer proposes a carefully designed rule-based vehicle racking scheme and apply it for the tracking for two well synchronized video sequences. In the scheme, almost all possible cases that can appear in the video-based vehicle tracking are considered to make rules. Also, the rule based scheme is augmented with Kalman filter. The result of tracking can be successfully used to collect data such as temporal variation of vehicle speed and behavior of individual vehicle behaviors in the enlarged tracking region.