• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.77-82
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• 2017

This paper related with the VSS_SE-MMA (Varying Step Size_Signed Error-MMA) which possible to improving the equalization performance that employing the varying adaptive step size based on the nonlinearities of error signal of SE-MMA (Signed Error-MMA), compensates the intersymbol interference by distortion occurs at the communication channel, in the transmitting the spectral efficient nonconstant modulus signal such as 16-QAM. The SE-MMA appeared to the reducing the computational arithematic operation using the polarity of error signal in the updating the tap coefficient of present MMA adaptive equalizer, but have a problem of equalization performance degradation. The VSS_SE-MMA improves the problem of such SE-MMA, using the varying step size consider the error signal in the update the adaptive equalizer tap coefficient, and its improved performance were confirmed by simulation. For this, the output signal constellation of equalizer, the residual isi and maximum distortion, MSE and SER were applied. As a result of computer simulation, it was confirmed that the VSS_SE-MMA algorithm has nearly same in convergence speed and has more good performance in every performance index at the steady state.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.4
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• pp.267-272
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• 2008

Mid-infrared (MIR) spectroscopy, particularly Fourier transform infrared spectroscopy (FTIR), has emerged as an important analytical tool in quantification as well as identification of multi-atomic inorganic ions such as nitrate. In the present study, the possibility of quantifying soil nitrate via diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) without change of a sample phase or with least treated samples was examined. Four types of soils were spectrally characterized in terms of unique bands of soil contents and interferences with nitrate bands in the range of $2000-1000cm^{-1}$. In order to reduce the effects of soil composition on calibration model for nitrate, spectra transformed to the 1st order derivatives were used in the partial least squared regression (PLSR) model and the classification procedure associated with input soil types was involved in calibration system. PLSR calibration models for each soil type provided better performance results ($R^2$>0.95, RPD>6.0) than the model considering just one type of soil as a standard.

• Journal of Environmental Policy
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• v.7 no.3
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• pp.141-160
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• 2008

The effects of disturbance on bird community were studied in Ssanggok Valley and Beopju Temple area, Songni Mt. National Park in $2006{\sim}2008$. We divided three sites by habitat condition such as traffic road(strong disturbance), trail(medium) and control(weak) site. During breeding and non-breeding seasons(n=12), number of species, number of individuals, species diversity and density did not differ among three sites, but in breeding season(n=9), number of species(Kruskal Wallis, $x^2$=10.32, p=0.006), number of individuals(Kruskal Wallis, $x^2$=7.118, p=0.028) and species diversity of birds(Kruskal Wallis, $x^2$=9.847, p=0.007) were significantly higher in trail site with medium disturbance than in other sites. In breeding season, nesting and foraging guild rate were not different among three sites. In guild analysis, hole was the highest nesting guild and canopy was the highest foraging guild in three sites.

• The Journal of the Acoustical Society of Korea
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• v.19 no.1
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• pp.16-24
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• 2000

In this paper the performance of a closed-loop power control scheme using variable step size decision method for DS/CDMA based-low earth orbit(LEO) mobile satellite systems in which the long round trip delay is a dominant performance degradation factor is evaluated. Because there are fundamental differences in the characteristics between the LEO mobile satellite channel and terrestrial mobile channel, such as long round trip delay and different elevation angle, these factors are considered in channel modeling based on the European Space Agency(ESA) measurement data. Since the round trip delay (from the mobile terminal to the gateway station via satellite) is typically 10∼20ms in low altitude satellite channels, closed-loop power control is much less effective than it is on a terrestrial channel. Thus, the adaptive power control scheme using a variable step size control is essential for overcoming the long round trip delay and fading due to the elevation angle. It is shown that the standard deviation of signal to interference ratio(SIR) adopting a variable step size closed-loop power control scheme is much less than that of a fixed step size closed-loop power control. Furthermore, we have driven the conclusion that the measurement interval of power control commands is optimal choice when it is twice the round trip delay.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2002.11a
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• pp.63-70
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• 2002

The main subject to become a hub pen is automation The automated container terminal has already operated in advanced pons and it bas been planned for the basic planning and operation design in domestic case. The key of automated container terminal is effective operation of both ATC(automated transfer crane) and AGV(automated guided vehicle) which is automated handling equipments. This is essential to productivity of automated container terminal. This study suggests the moat optimal method of equipment operation in order to minimize loading time using each three types of effective AT operation methods and AGV dispatching rules in automated container terminals. As the automated equipment operation causes unexpected deadlocks or interferences, it should be proceeded on event-based real tine. Therefore we propose the most effective ATC operation methods and AGV dispatching rules in this paper. The various states occurred in real automated container terminals are simulated to evaluate these methods. This experiment will show the most robust automated equipment operation method on various parameters(the degree of yard re-marshaling, the number of containers and the number of AGVs).

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.4
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• pp.43-48
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• 2015

We studied on pseudo-range correction(PRC) modeling in order to improve differential GNSS(DGNSS) accuracy. The PRC is the range correction information that provides improved location accuracy using DGNSS technique. The digital correction signal is typically broadcast over ground-based transmitters. Sometimes the degradation of the positioning accuracy caused by the loss of PRC signals, radio interference, etc. To prevent the degradation, in this paper, we have designed a PRC model through polynomial curve fitting and evaluated this model. We compared two quantities, estimations of PRC using model parameters and observations from the reference station. In the case of GPS, the average is 0.1m and RMSE is 1.3m. Most of GPS satellites have a bias error of less than ${\pm}1.0m$ and a RMSE within 3.0m. In the case of GLONASS, the average and the RMSE are 0.2m and 2.6m, respectively. Most of satellites have less than ${\pm}2.0m$ for a bias error and less than 3.0m for RMSE. These results show that the estimated value calculated by the model can be used effectively to maintain the accuracy of the user's location. However;it is needed for further work relating to the big difference between the two values at low elevation.

• Tunnel and Underground Space
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• v.30 no.4
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• pp.306-319
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• 2020

Characterizations of Excavation Damage Zone (EDZ), which is hydro-mechanical degrading the host rock, are the important issues on the geological repository for the spent nuclear fuel. In the DECOVALEX 2019 project, Task G aimed to model the fractured rock numerically, describe the hydro-mechanical behavior of EDZ, and predict the change of the hydraulic factor during the lifetime of the geological repository. Task G prepared two-dimensional fractured rock model to compare the characteristics of each simulation tools in Work Package 1, validated the extended three-dimensional model using the TAS04 in-situ interference tests from Äspö Hard Rock Laboratory in Work Package 2, and applied the thermal and glacial loads to monitor the long-term hydro-mechanical response on the fractured rock in Work Package 3. Each modelling team adopted both Finite Element Method (FEM) and Discrete Element Method (DEM) to simulate the hydro-mechanical behavior of the fracture rock, and added the various approaches to describe the EDZ and fracture geometry which are appropriate to each simulation method. Therefore, this research can introduce a variety of numerical approaches and considerations to model the geological repository for the spent nuclear fuel in the crystalline fractured rock.

• Korean Journal of Remote Sensing
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• v.34 no.2_2
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• pp.313-326
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• 2018

This paper introduces core techniques on ship detection and tracking based on a compact HF radar platform which is necessary to establish a wide-area surveillance network. Currently, most HF radar sites are primarily optimized for observing sea surface radial velocities and bearings. Therefore, many ship detection systems are vulnerable to error sources such as environmental noise and clutter when they are applied to these practical surface current observation purpose systems. In addition, due to Korea's geographical features, only compact HF radars which generates non-uniform antenna response and has no information on target information are applicable. The ship detection and tracking techniques discussed in this paper considers these practical conditions and were evaluated by real data collected from the Yellow Sea, Korea. The proposed method is composed of two parts. In the first part, ship detection, a constant false alarm rate based detector was applied and was enhanced by a PCA subspace decomposition method which reduces noise. To merge multiple detections originated from a single target due to the Doppler effect during long CPIs, a clustering method was applied. Finally, data association framework eliminates false detections by considering ship maneuvering over time. According to evaluation results, it is claimed that the proposed method produces satisfactory results within certain ranges.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.61-69
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• 2011

Fiber Reinforced Plastic (FRP) sheets have been widely used to retrofit and rehabilitate RC structures, while in case of retrofitting steel structures, there are no codes and researches. It stems from configuration of member and characteristics of bonding behavior. This study focused on the static behavior of steel beams reinforcement by AFRP sheets. The main objective of the experimental programme was the evaluation of the force transfer mechanism, the increment of the beam load carrying capacity and the bending stiffness. A bending test was conducted on a H-shaped steel beam, with aramid FRP sheets bonded to its flanges. The mid-span deflection and the strain from three points along AFRP sheets were recorded Test results exhibit that the increment of the load-carrying capacity with reference to a mid-span deflection level of 15 mm(1/125mm of the clear span) was equal to 9.4% and for the two layers case, an elastic stiffness increment is slightly higher than one layer case.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.3
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• pp.191-201
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• 2015

Measuring and mapping connectivity among habitats is a key component of sustainable urban planning and design process. In this study, we examined how functional corridors connect forest bird habitats in a metropolitan area of Korea using graph theory-based techniques. High-quality forest habitat was defined as a function of forest cover, presence of residential areas, and road networks. We then constructed a network of high-quality forest habitats using the FunConn (functional connectivity) tools, and computed metrics ($T_i$) of patch importance based on the minimum ($Q_1$) and the 25th percentile ($Q_{25}$) rank least-cost distance values. We investigated the relative influence of two values of patch importance on forest bird species richness. As a result, the patch importance index based on the $Q_{25}$ effective distance threshold was most positively correlated with species richness (P < 0.001) after controlling for the area effect. Thus, using the $Q_{25}$ effective distance threshold, we mapped not only the locations of important habitat patches and functional corridors, but also the network backbone of forest bird habitats. The network developed in this study can help guide urban planning for biodiversity conservation.