• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.23 no.4
• /
• pp.77-93
• /
• 2024

The recent development of data collection technology, which conveys various travel data in real-world such as mobile data and probe vehicle data, facilitates transportation planners identifying specified spatio-temporal travel patterns. In this study, an easily implementable travel mode classification methodology was proposed to classify inter-regional trip-modes without modeling by superimposing trajectories generated from mobile phone signaling and transportation infrastructure points into a polygon scale of a shapefile in a GIS system. Each regional mode trip was classified according to the rules such as the presence of transportation infrastructure in the trip trajectory, travel time, and the presence of access trips. An accuracy test generates Type I and Type II error results table to verify the proposed methodology. As a result, it was found that the methodology developed showed the F1-Score of the air mode 1.00, rail mode 0.95, bus mode 0.73.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.9
• /
• pp.68-73
• /
• 2013

In this paper, we proposed a readout circuit of pulse waveform and rate for a U-health system to monitor health condition. For long-time operation without replacing or charging a battery, either pulse waveform or pulse rate is selected as the output data of the proposed readout circuit according to health condition of a user. The proposed readout circuit consists of a simple digital logic discriminator and a dual-mode ADC which operates in the ADC mode or in the count mode. Firstly, the readout circuit counts pulse rate for 4 seconds in the count mode using the dual-mode ADC. Health condition is examined after the counted pulse rate is accumulated for 1 minute in the discriminator. If the pulse rate is out of the preset normal range, the dual-mode ADC operates in the ADC mode where pulse waveform is converted into 10-bit digital data with the sampling frequency of 1 kHz. These data are stored in a buffer and transmitted by 620 kbps to an external monitor through a RF transmitter. The data transmission period of the RF transmitter depends on the operation mode. It is generally 1 minute in the normal situation or 1 ms in the emergency situation. The proposed readout circuit was designed with $0.11{\mu}m$ process technology. The chip area is $460{\times}800{\mu}m^2$. According to measurement, the power consumption is $161.8{\mu}W$ in the count mode and $507.3{\mu}W$ in the ADC mode with the operating voltage of 1 V.

• The KIPS Transactions:PartD
• /
• v.18D no.5
• /
• pp.371-384
• /
• 2011

This paper considers logistics decision support system which deals with transportation mode selection considering transportation and carbon emission cost. Transportation and carbon emission costs vary with the choice of transportation modes and to become competitive companies need to find proper transportation modes for their logistics services. However, due to the restricted capacity of transportation modes, it is difficult to balance transportation and carbon emission costs when designing logistics network including transportation mode choice for each service. Therefore this paper aims to analyze the trade-off relationship between transportation and carbon emission cost in mode selection of intermodal transportation and to provide optimal green logistics strategy. In this paper, the logistics decision support system is designed based on mixed integer programming model. To understand the trade-off relationship of transportation and carbon emission cost, the system is tested with various scenarios including transportation of containers between Seoul and Busan. The analysis results show that, even though sea transportation combined with trucking is competitive in carbon emission per unit distance travelled, the total cost of carbon emission and transportation for the sea transportation may not have competitive advantage over other transportation modes including rail and truck transportation modes. The sea-based intermodal logistics service may induce detours which have negative impacts on the overall carbon emission. The proposed logistics decision support system is expected to play key role in green logistics and supply chain management.

• The Mathematical Education
• /
• v.61 no.4
• /
• pp.597-612
• /
• 2022

Recently, large-scale mathematics assessments are shifting from traditional paper-based tests to computer-based tests, nationally and internationally. This study explored the mode effect (the difference in student achievement by the change of test mode) according to the types of test items, the technological function reflected in the items, the characteristics of students' computer use, and the computer-based test environment. To this end, we analyzed the results of the 2020 national assessment of educational achievement of high school mathematics conducted on a paper and computer basis. As a result, firstly, the mode effect induced by the mode transition was generally insignificant, but the mode effect was larger in the extended response type than other types. Secondly, there were differences in the mode effect according to the transition to test with computer mode where innovative items were added. Thirdly, the difference between mode effects was statistically significant according to the student's sense of efficacy in computer use. The results of this study suggest that innovative items should be introduced deliberately according to the targeted content and competency in evaluation, and that assessment design and environment preparation need to be carefully developed so that nonessential abilities other than students' mathematical ability or incidental situation do not distort the assessment results.

• The Journal of the Acoustical Society of Korea
• /
• v.16 no.4
• /
• pp.94-100
• /
• 1997

In order to investigate the radiation of sound from the King Song-Duk bell, we measured the sound pressure around the bell at every 30$^{\circ}$ using a microphone line array which was composed of 30 microphones separated by 15cm;total number of measurement point was 360. The sound field was estimated by using cylindrical acoustic holography. The spectrum of measured sound pressure demonstrates that it is almost like white noise in the very beginning, but in 10 seconds two close frequency components(64.06Hz, 64.38Hz) remain and make a famous beating. This beating sound is often believed to make unique sound of the King Song-Duk bell. The mode shapes of that frequency components are the same except that one is rotated by 45$^{\circ}$ from the other. This phenomenon occurs at the other pairs of components are the same except ones in very high frequency range where the mode shapes are rather complex.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.15 no.4
• /
• pp.240-250
• /
• 2015

The development of the control algorithms for under-actuated systems is important. Decoupled sliding mode control has been successfully employed to control under-actuated systems in a decoupling manner with the use of sliding mode control. However, in such a control scheme, the system functions must be known. If there are uncertainties in those functions, the control performance may not be satisfactory.In this paper, the direct adaptive fuzzy sliding mode control is employed to control a class of under-actuated uncertain systems which can be regarded as a combination of several subsystems with one same control input. By using the hierarchical sliding control approach, a sliding control law is derived so as to make every subsystem stabilized at the same time. But, since the system considered is assumed to be uncertain, the sliding control law cannot be readily facilitated. Therefore, in the study, based on Lyapunov stable theory a fuzzy compensator is proposed to approximate the uncertain part of the sliding control law. From those simulations, it can be concluded that the proposed compensator can indeed cope with system uncertainties. Besides, it can be found that the proposed compensator also provide good robustness properties.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.76.1-76.1
• /
• 2015

Optical resonances of metallic or dielectric nanoantennas enable to effectively convert free-propagating electromagnetic waves to localized electromagnetic fields and vice versa. Plasmonic resonances of metal nanoantennas extremely modify the local density of optical states beyond the optical diffraction limit and thus facilitate highly-efficient light-emitting, nonlinear signal conversion, photovoltaics, and optical trapping. The leaky-mode resonances, or termed Mie resonances, allow dielectric nanoantennas to have a compact size even less than the wavelength scale. The dielectric nanoantennas exhibiting low optical losses and supporting both electric and magnetic resonances provide an alternative to their metallic counterparts. To extend the utility of metal and dielectric nanoantennas in further applications, e.g. metasurfaces and metamaterials, it is required to understand and engineer their scattering characteristics. At first, we characterize resonant plasmonic antenna radiations of a single-crystalline Ag nanowire over a wide spectral range from visible to near infrared regions. Dark-field optical microscope and direct far-field scanning measurements successfully identify the FP resonances and mode matching conditions of the antenna radiation, and reveal the mutual relation between the SPP dispersion and the far-field antenna radiation. Secondly, we perform a systematical study on resonant scattering properties of high-refractive-index dielectric nanoantennas. In this research, we examined Si nanoblock and electron-beam induced deposition (EBID) carbonaceous nanorod structures. Scattering spectra of the transverse-electric (TE) and transverse-magnetic (TM) leaky-mode resonances are measured by dark-field microscope spectroscopy. The leaky-mode resonances result a large scattering cross section approaching the theoretical single-channel scattering limit, and their wide tuning ranges enable vivid structural color generation over the full visible spectrum range from blue to green, yellow, and red. In particular, the lowest-order TM01 mode overcomes the diffraction limit. The finite-difference time-domain method and modal dispersion model successfully reproduce the experimental results.

• Journal of Korean Society for Atmospheric Environment
• /
• v.31 no.2
• /
• pp.131-142
• /
• 2015

This study investigated physicochemical and optical characteristics for three episodes of Asian dust, stagnant haze and long-range transport haze and for one clean day. $PM_{10}$ mass concentration during Asian dust and two haze days was increased by 2~9 times compared to that of clean episode. During Asian dust episode, coarse particle concentration was increased and the mass concentration of calcium in a coarse mode ($1.8{\sim}10{\mu}m$) was $5.4{\mu}g/m^3$ which was 7 times higher than that of clean episode. The calcium was presented as a form of $CaCO_3$ in a coarse mode. During the two haze episodes, fine particle (< $1.8{\mu}m$) concentration was increased and secondary inorganic pollutants such as sulfate, ammonium and nitrate composed of 90% of the total ions. $(NH_4)_2SO_4$ and $NH_4NO_3$ were dominant in a fine mode for stagnant haze episode. But they were the most dominant form in both fine mode and coarse mode for long-range transport haze episode. According to the optical properties for each episode (Asian dust, stagnant haze and long-range transport haze) were classified as dust, black carbon and mixture, respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.3
• /
• pp.205-210
• /
• 2001

In this paper, a novel compound mode logic based on the advantage of both CMOS logic and pass-transistor logic(PTL) is proposed. From the experimental results, the power-delay products of the compound mode logic is about 22% lower than that of the conventional CMOS logic, when we design a full adder. With the proposed logic, a high performance 32$\times$32-bit multiplier has been fabricated with 0.6um CMOS technology. It is composed of an improved sign select Booth encoder, an efficient data compressor based on the compound mode logic, and a 64-bit conditional sum adder with separated carry generation block. The Proposed 32$\times$32-bit multiplier is composed of 28,732 transistors with an active area of 1.59$\times$1.68 mm2 except for the testing circuits. From the measured results, the multiplication time of the 32$\times$32-bit multiplier is 9.8㎱ at a 3.3V power supply, and it consumes about 186㎽ at 100MHz.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.3
• /
• pp.59-66
• /
• 2015

In this paper, we propose a method of improving the light-load efficiency of DC-DC buck converter using 4bit SAR-ADC (Successive Approximation ADC) for a LDO or a power transistor size selection technique. The proposed circuit selects power transistor sizes depending on load current so that improves the light-load efficiency of the DC-DC buck converter. For this, we select the power transistor size with a cross point of the switching loss and the conduction loss. Also, when the IC operates in standby mode or sleep mode, a LDO mode is selected for improving the efficiency. The proposed circuit selects power transistor sizes(X1, X2, X4, X8) with 4 bits and its efficiency is higher about the maximum of 25% at the light-load than that of a single transistor size. Input voltage and output voltage are 5V and 3.3V for maximum load currents of 500mA.