• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.871-876
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• 2023

In this paper, we deal with the stable conditions when two uncertainties exist simultaneously in a linear discrete time-varying interval system with time-varying delay time. The interval system is a system in which system matrices are given in the form of an interval matrix, and this paper targets the system in which the delay time of these interval system matrices and state variables is time-varying. We propose the system stability condition when there is simultaneous unstructured uncertainty that includes nonlinearity and only its magnitude and uncertainty in the system matrix of delayed state variables. The stable bounds for two types of uncertainty are derived as an analytical equation. The proposed stability condition and bounds can include previous stability condition for various linear discrete systems, and the values such as time-varying delay time variation size, uncertainty size, and range of interval matrix are all included in the conditional equation. The new bounds of stability are compared with previous results through numerical example, and its effectiveness and excellence are verified.

• Journal of KIBIM
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• v.7 no.3
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• pp.1-10
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• 2017

3D concrete printing technology builds structural components layer-by-layer with concrete extruded through a nozzle without using forms. This technology can simplify construction processes by optimizing design flexibility, construction time, and cost. Furthermore, the 3D printing technology is easy to make an irregularly shaped and function embedded building(or object) which is difficult to be constructed by conventional construction method. However, the 3D printing concrete is not suitable for current commercial standard and the material itself. It is also difficult to apply it to the construction site due to the lack of initial strength and the nozzle which is clogged during the process. The research of mix proportion design process for 3D printing concrete which differs from the conventional concrete is necessary in order to solve the problems. This paper aims to calculate the 3D printing concrete mix proportion design process based on the mix materials and performance information derived from the previous researches. Therefore, the usage variation range, mutual influence relationship, and the importance priority of the mix proportion are analyzed. Based on this results, the basic design process of 3D printing concrete which contains planning design phase, basic design phase and validating performance phase is suggested. We anticipate to confirm applicability verification about the actual production by referring to this 3D printing concrete mix proportion study. In the future, this study can be utilized for blueprint of the 3D printing concrete mix proportion.

• Journal of Korea Multimedia Society
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• v.9 no.7
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• pp.894-903
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• 2006

Rapid technology growth of hardware have brought about development and expansion of various digital motion pictured information including 3-Dimension. 3D digital techniques can be used to be diversity in Animation, Virtual-Reality, Movie, Advertisement, Game and so on. 3D characters in digital motion picture take charge of the core as to communicate emotions and information to users through sounds, facial expression and characteristic motions. Concerns about 3D motion and facial expression is getting higher with extension of frequency in use and range about 3D character design. In this study, the facial expression can be used as a effective method about implicit emotions will be studied and research 3D character's facial expressions and muscles movement which are based on human anatomy and then try to find effective method of facial expression. Finally, also, study the difference and distinguishing between 2D and 3D character through the preceding study what I have researched before.

• Journal of Navigation and Port Research
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• v.30 no.1 s.107
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• pp.113-117
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• 2006

The object qf this experiment was the evaluation of the growth rate of frost layer conditioned by inlet air's velocity, temperature and relative humidity on the copper tube in evaporator. In this experiment, the inlet air's velocity were $0.3^m/_s,\;0.6^m/_s,\;0.9^m/_s,$ temperature were $15^{\circ}C,\;20^{\circ}C,\;25^{\circ}C$ and the variation of relative humidity was $70\%~90\%$. And the brine temperature flowing through the copper tubes was kept $-15{\circ}C$ because generally cooling temperature range is constantly $-15^{\circ}C$ in the heat exchanger for air conditioning system It was found that the amount of frost generation increased so that the relative humidity, velocity and temperature of supply air increased.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.378-384
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• 2013

In this paper, a CMOS temperature sensor is proposed to measure the internal temperature of a chip. The temperature sensor consists of a proportional-to-absolute-temperature (PTAT) circuit for a temperature sensing part and a 4-bit analog-to-digital converter (ADC) for a digital interface. The PTAT circuit with the compact area is designed by using a vertical PNP architecture in the CMOS process. To reduce sensitivity of temperature variation in the digital interface circuit of the proposed temperature sensor, a 4-bit successive approximation (SA) ADC using the minimum analog circuits is used. It uses a capacitor-based digital-to-analog converter and a time-domain comparator to minimize power consumption. The proposed temperature sensor was fabricated by using a $0.25{\mu}m$ 1-poly 6-metal CMOS process with a 2.5V supply, and its operating temperature range is from 50 to $150^{\circ}C$. The area and power consumption of the fabricated temperature sensor are $130{\times}390{\mu}m^2$ and $868{\mu}W$, respectively.

• Journal of Korea Multimedia Society
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• v.16 no.11
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• pp.1325-1337
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• 2013

Music affects sensitivity and emotion of human, emotional power of the music has been applied to various fields. Especially, to visualize as well as listen to music is able to create various atmosphere. In this paper, we proposed sensitivity control system for interaction with people to merge music and lighting. Because existing FT(Fourier Transform) has not information about the time, to analyze information of changed signal according to the time is difficult. In order to solve such a problem, we use STFT(Short Time Fourier Transform) method to analyze music signal. and also, we classified music for three genre and compared the frequency characteristics according to genre, and control the color, brightness of LED light based on the frequency components within analysis range. Unlike existing LED lighting control study using music, we had color control of emotional lighting and brightness control using variation amount of music signal in this paper. Proposed lighting control system will be able to utilize various industry fields as well as emotional lighting.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.808-814
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• 2001

The electrical properties and stabiltiy of Pr$_{6}$O$_{11}$ -based ZnO varistors, which are composed of ZnO-Pr$_{6}$O$_{11}$-Cr$_{2}$O$_{3}$-Er$_{2}$O$_{3}$ based ceramics, were investigated in the Er$_{2}$O$_{3}$ content range of 0.5 to 2.0 mol%. As Er$_{2}$O$_{3}$content is increased up to approximaterly 1.0mol%, the nonlinearity was decreased. Increasing Er$_{2}$O$_{3}$ content further caused the nonlinearity to increase. The varistors with 2.0 mol% Er$_{2}$O$_{3}$ exhibited a high nonlinearity, in which the nonlinear exponent is 47.41 and the leakage current is 1.82 $\mu$A. Furthermore, they showed a very excellent stability, in which the variation rates of the varistor voltage, the nonlinear exponent, and leakage current are -0.52%, -4.09%, and 152.75%, respectively, under DC accelerated aging stress, such as (0.80 V$_{1mA}$9$0^{\circ}C$/12h)+(0.85 V$_{1mA}$115$^{\circ}C$/12h)+(0.90 V$_{1mA}$12$0^{\circ}C$/12h)+(0.95 V$_{1mA}$1$25^{\circ}C$/12h)+(0.95 V$_{1mA}$1$25^{\circ}C$/12h).2h).TEX>/12h).2h).

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.397-400
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• 2006

In this study, we experimentally investigate the possibility of skin-friction drag reduction by series of transverse cavities in a turbulent boundary layer flow. The effects of cavity depth (d), cavity length (l) and cavity spacing (s) on the skin friction drag are examined in the range of $Re_{\theta}\;=\;4030\;{\sim}\;7360$, $d/{\theta}_0\;=\;0.13\;{\sim}1.03$, l/d = 1 ~ 4 and s/d = 5 ~ 20. We perform experiments for twenty different cavity geometries and directly measure total drag force using in-house force measurement system. In most cases, the skin friction drag is increased. At several cases, however, small drag reduction is obtained. The variation of the skin ftiction drag is more sensitive to the cavity length than to the cavity depth or cavity spacing, and drag is reduced at $s/l\;{\geq}\;10$ and $l/{\theta}_0\;{\leq}\;0.26$ irrespective of the cavity depth. At $l/\bar{\theta}_0\;=\;0.13$ and s/l = 10, maximum 2% drag reduction is achieved. When the skin friction drag is reduced, there is little interaction between the flows inside and outside cavity, and the flow changed by the cavity is rapidly recovered at the following crest. A stable vortex is formed inside a cavity in the case of drag reduction. This vortex generates negative skin friction drag at the cavity bottom wall. Although there is form drag due to the cavity itself, total drag is reduced due to the negative skin friction drag.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.113-121
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• 1998

In natural convection flows, the fluid velocities are highly dependent on the thermal field and property variations can have a strong effect on both the flow and thermal fields. To examine the effect of property variations, at first, numerical analyses covering wide range of the Prandtl number under the same Rayleigh numbers have been carried out. Next, we have modeled the viscosity and thermal conductivity as parabolic functions of temperature and a comprehensive set of numerical solutions have been obtained to understand the effect. The Prandtl number dependence of Nusselt number is fairly strong even though the effect is still weak compared to the Rayleigh number dependence. When thermophysical properties are dependent on temperature, the flow field showed a fairly weak variation except near boundaries, whereas the temperature field is strongly affected, especially by the temperature dependent thermal conductivity.

• Journal of Environmental Science International
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• v.23 no.4
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• pp.637-647
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• 2014

Quantitative assessment of groundwater level change under extreme event is important since groundwater system is directly affected by drought. Substantially, groundwater level fluctuation reveals to be delayed from several hours to few months after raining according to the aquifer characteristics. Groundwater system in Jeju Island would be also affected by drought and almost all regions were suffered from a severe drought during summer season (July to September) in 2013. To estimate the effect of precipitation to groundwater system, monthly mean groundwater levels in 2013 compared to those in the past from 48 monitoring wells belong to be largely affected by rainfall(Dr) over Jeju Island were analyzed. Mean groundwater levels during summer season recorded 100 mm lowered of precipitation compared to the past 30 years became decreased to range from 2.63 m to 5.42 m in southern region compared to the past and continued to December. These decreasing trends are also found in western(from -1.21 m to -4.06 m), eastern(-0.91 m to -3.24 m), and northern region(from 0.58 m to -4.02 m), respectively. Moreover, the response of groundwater level from drought turned out to be -3.80 m in August after delaying about one month. Therefore, severe drought in 2013 played an important role on groundwater system in Jeju Island and the effect of drought for groundwater level fluctuation was higher in southern region than other ones according to the regional difference of precipitation decrease.