• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.177-183
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• 1999

In this paper, we analyze transmission characteristics of ultrashort laser pulses using the property of Raised-cosine pulse which are systematically obtained following Class-2 PRS model. The high-order pulses are easily derived front a modified PRS system model as Class-1 PRS model. This may be based on the fact that the spectra and bandwidths of the high-order pulses are beautifully related to their orders. And we make clear they are very useful to cover wider area and more accurate transmission characteristics of ultrashort pulses than Gaussian or Sech pulse approximations used conventionally. First modifying the generalized PRS system model, we propose a new model for deriving any type of high-order pulse. And we offer a novel analysis method of ultrashort pulse transmission which has any shape and FWHM, using the proposed model. In addition, by fixing the pulse range $\tau$=1(ps) and varying the order of the pulse from n=1 to n=100, we obtain spectra of ultrashort pulses with 1(ps)-100(fs) FWHM's, and width of FWHM in the Class-2 PRS model 50~100(fs) smaller than Class-1 PRS model. As a one-step further, we derive PSD's of their pulse trains when they are applied to Unipolar signaling scheme. These PSD's are derided in the range of possible pulse intervals. All of these results are not only coincided with some conventional experimental works but also will to applied to any pioneering ultrashort pulse in the future.

• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.63-76
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• 2008

The goals of this study are to develop travel time functions based on intersection delay and to analyze the applicability of the functions to traffic assignment models. The study begins with the premise that the existing assignment models can not effectively account for intersection delay time. In pursuing the goals, this study gives particular attention to dividing the link travel time into link moving time and stopped time at node, making the models based on such variables as the travel speed, volume, geometry, and signal data of signalized intersections in Cheongju, and analyzing the applicability of these models to traffic assignment. There are several major findings. First, the study presents the revised percentage of lanes (considering type of intersection) instead of g/C for calculating intersection delay, which is analyzed to be significant in the paired t-test. Second, the assigned results of applying these models to the Cheongju network in EMME/2 are compared with the data observed from a test car survey in Cheongju. The analyses show that the BPR models do not consider the intersection delay, but the modified uniform delay model and modified Webster model are comparatively well fitted to the observed data. Finally, the assigned results of applying these models are statistically compared with the test car survey data in assigned volume, travel time, and average speed. The results show that the estimates from the divided travel time model are better fitted to observed data than those from the BPR model.

• Development and Reproduction
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• v.12 no.3
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• pp.243-250
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• 2008

Mast cells containing a variety of mediators in their cytoplasmic granules are widely distributed in connective tissues and mucosal surfaces of skin, airways, and guts. Within these tissues, mast cells are involved in the pathophysiological conditions such as inflammation, self-defense, tissue-remodeling, and autoimmunity. In order to understand the functional roles of master cells in the uterus, we histologically examined the distribution and density of uterine mast cells in the different aged mice. Until 6 weeks mast cells were sparsely detected in the uterus. But at 7 weeks after birth, when estrous cycle begins, the number of mast cells within uterine tissues increased dramatically and the increment of mast cell density continued up to 32 weeks-age. After then, uterine glandular tissue degenerated gradually and density of uterine mast cell decreased. Uterine mast cells were mainly found in the myometrium and they were closely associated with smooth muscle cells, fibroblasts, and collagens, which contents were changed according to the uterine development in the myometrium. These results suggest that uterine mast cells could be involved in myometrial contractions mediated by smooth muscle cells and tissue reconstitution or remodeling during estrous cycle and parturition including the various immunological functions.

• Journal of the Korean Geotechnical Society
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• v.24 no.2
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• pp.87-97
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• 2008

Behaviors of cemented engineered soils, composed of rigid sand particle and soft rubber particle, are investigated under $K_o$ condition. The uncemented and cemented specimens are prepared with various sand volume fractions to estimate the effect of the cementation in mixtures. The vertical deformation and elastic wave velocities with vertical stress are measured. The bender elements and PZT sensors are used to measure elastic wave velocities. After cementation, the slope of vertical strain shows bilinear and is similar to that of uncemented specimen after decementation. Normalized vertical strains can be divided into capillary force, cementation, and decementation region. The first deflection of the shear wave in near field matches the first arrival of the primary wave. The elastic wave velocities dramatically increase due to cementation hardening under the fixed vertical stress, and are almost identical with additional stress. After decementation, the elastic wave velocities increase with increase in the vertical stress. The effect of cementation hinders the typical rubber-like, sand-like, and transition behaviors observed in uncemented specimens. Different mechanism can be expected in decementation of the rigid-soft particle mixtures due to the sand fraction. a shape change of individual particles in low sand fraction specimens; a fabric change between particles in high sand fraction specimens. This study suggests that behaviors of cemented engineered soils, composed of rigid-soft particles, are distinguished due to the cementation and decementation from those of uncemented specimens.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.6
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• pp.124-131
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• 2017

Recently, drone is extending its range of usability. For example, the delivery, agriculture, industry, and entertainment area take advantage of drone mobilities. To control real drones, it needs huge amount of drone control training steps. However, it is risky; falling down, missing, destroying. The virtual drone system can avoid such risks. We reason that what kinds of technologies are required for building the virtual drone system. First, it needs that the virtual drone authoring tool that can assemble drones with the physical restriction in the virtual environment. We suggest that the drone assembly method that can fulfill physical restrictions in the virtual environment. Next, we introduce the virtual drone simulator that can simulate the assembled drone moves physically right in the virtual environment. The simulator produces a high quality rendering results more than 60 frames per second. In addition, we develop the physics engine based on SILS(Software in the loop simulation) framework to perform more realistic drone movement. Last, we suggest the virtual drone controller that can interact with real drone controllers which are commonly used to control real drones. Our virtual drone system earns 7.64/10.0 user satisfaction points on human test: the test is done by one hundred persons.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.8
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• pp.52-59
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• 2007

In this paper, we analyzed and measured implant isolation characteristics for a 1.25 Gbps monolithic integrated hi-directional (M-BiDi) optoelectronic system-on-a-chip, which is a key component to constitute gigabit passive optical networks (PONs) for a fiber-to-the-home (FTTH). Also, we derived an equivalent circuit of the implant structure under various DC bias conditions. The 1.25 Gbps M-BiDi transmit-receive SoC consists of a laser diode with a monitor photodiode as a transmitter and a digital photodiode as a digital data receiver on the same InP wafer According to IEEE 802.3ah and ITU-T G.983.3 standards, a receiver sensitivity of the digital receiver has to satisfy under -24 dBm @ BER=10-12. Therefore, the electrical crosstalk levels have to maintain less than -86 dB from DC to 3 GHz. From analysed and measured results of the implant structure, the M-BiDi SoC with the implant area of 20 mm width and more than 200 mm distance between the laser diode and monitor photodiode, and between the monitor photodiode and digital photodiode, satisfies the electrical crosstalk level. These implant characteristics can be used for the design and fabrication of an optoelectronic SoC design, and expended to a mixed-mode SoC field.

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.141-152
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• 2020

The rapid on-site measurement of hydroponic nutrients allows for the more efficient use of crop fertilizers. This paper reports on the development of an embedded on-site system consisting of multiple ion-selective electrodes (ISEs) for the real-time measurement of the concentrations of macronutrients in hydroponic solutions. The system included a combination of PVC ISEs for the detection of NO₃, K, and Ca ions, a cobalt-electrode for the detection of H₂PO₄, a double-junction reference electrode, a solution container, and a sampling system consisting of pumps and valves. An Arduino Due board was used to collect data and to control the volume of the sample. Prior to the measurement of each sample, a two-point normalization method was employed to adjust the sensitivity followed by an offset to minimize potential drift that might occur during continuous measurement. The predictive capabilities of the NO₃ and K ISEs based on PVC membranes were satisfactory, producing results that were in close agreement with the results of standard analyzers (R² = 0.99). Though the Ca ISE fabricated with Ca ionophore II underestimated the Ca concentration by an average of 55%, the strong linear relationship (R² > 0.84) makes it possible for the embedded system to be used in hydroponic NO₃, K, and Ca sensing. The cobalt-rod-based phosphate electrodes exhibited a relatively high error of 24.7±9.26% in the phosphate concentration range of 45 to 155 mg/L compared to standard methods due to inconsistent signal readings between replicates, illustrating the need for further research on the signal conditioning of cobalt electrodes to improve their predictive ability in hydroponic P sensing.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.175-185
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• 2000

This paper described on a basic study to organize fishing vessel control system in order to control efficiently fishing vessel in Korean offshore. It was digitalized ARPA image on the fishing processing of a fleet of purse seiner in conducting fishing operation at Cheju offshore in Korea as a digital camera and then simulated by used VTMS. Futhermore, it was investigated on the application of FVTMS which can control efficiently fishing vessels in fishing ground. The results obtained were as follows ; (1) It was taken 16 minutes and 35 minutes to casting and hauling net in fishing processing respectively. The length of rope pulled by scout boat was 200m, tactical diameter in casting net was 340.8m, turning speed was 6kts as well. (2) The processing of casting and hauling net was moved to SW, NE as results of simulation when the current direction and speed set into NE, 2kts and SW, 2kts respectively. Such as these results suggest that can predict to control the fishing vessel previously with information of fishing ground, fishery and ship's maneuvering, etc. (3) The control range of VTMS radar used in simulation was about 16 miles. Although converting from a radar of the control vessel to another one, it was continuously acquired for the vector and the target data. The optimum control position could be determined by measuring and analyzing to distance and direction between the control vessel and the fleet of fishing vessel. (4) The FVTMS(fishing vessel traffic management services) model was suggested that fishing vessels received fishing conditions and safety navigation information can operate safely and efficiently.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.248-256
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• 2007

In this paper, we propose a selective DFT spreading method to solve a high PAPR problem in uplink OFDMA system. A selective characteristic is added to the DFT spreading, so the DFT spreading method is mixed with SLM method. However, to minimize increment of computational complexity, differently with common SLM method, our proposed method uses only one DFT spreading block. After DFT, several copy branches are generated by multiplying with each different matrix. This matrix is obtained by linear transforming the each phase rotation in front of DFT block. And it has very lower computational complexity than one DFT process. For simulation, we suppose that the 512 point IFFT is used, the number of effective sub-carrier is 300, the number of allowed sub-carrier to each user's is 1/4 and 1/3 and QPSK modulation is used. From the simulation result, when the number of copy branch is 4, our proposed method has more than about 5.2 dB PAPR reduction effect. It is about 1.8 dB better than common DFT spreading method and 0.95 dB better than common SLM which uses 32 copy branches. And also, when the number of copy branch is 2, it is better than SLM using 32 copy branches. From the comparison, the proposed method has 91.79 % lower complexity than SLM using 32 copy branches in similar PAPR reduction performance. So, we can find a very good performance of our proposed method. Also, we can expect the similar performance when all number of sub-carrier is allocated to one user like the OFDM.