• Proceedings of the KSR Conference
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• 1999.11a
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• pp.280-287
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• 1999

An automatic train operation(ATO) system executes the operation of constant speed travelling and fixed point parking by using microprocessors instead of drivers manual operation. This paper describes the mathematical model for the train considering unknown disturbances which consist of start resistance, travelling resistance, slope resistance, curve resistance, and so on. The speed controller of ATO system is designed by considering the disturbances. The simulation is executed to verify the speed control and fixed point parking performance and to compare its performance with that of a PID-type ATO control system under disturbances. Simulation results show that the control performance of gain scheduled control scheme fur ATO system is better than that of the conventional PID controller.

• Current Optics and Photonics
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• v.2 no.5
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• pp.443-447
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• 2018

We propose a diode-pumped cesium laser using frequency locking of a pump laser that can effectively increase the maximum output power of the cesium laser. We simultaneously monitored the absorption spectrum of cesium and the laser output power, and the frequency of pump laser was locked at the center of the $D_2$ absorption line of the cesium atom to obtain an effective gain enhancement. Using this scheme, we have achieved output power increase of ~0.1 W compared to when frequency locking was not applied. Furthermore, by optimizing the temperature of the cesium cell and the reflectivity of the output coupler, we successfully achieved an output power of 1.4 W using the pump power of 2.9 W, providing a slope efficiency of 61.5% and optical-to-optical efficiency of 49%.

• ETRI Journal
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• v.43 no.6
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• pp.978-990
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• 2021

This article presents techniques for improved estimation of symbol timing offset (STO) and carrier frequency offset (CFO) for dual-polarization (DP) orthogonal frequency division multiplex (DP-OFDM) systems. Recently, quaternion multiple-input multiple-output OFDM has been proposed for high spectral efficiency communication systems, which can flexibly explore different types of diversities such as space, time, frequency, and polarization. This article focuses on synchronization techniques for DP-OFDM systems using a cyclic prefix, where the application of quaternion algebra leads to new improved estimators. Simulations performed for DP system methods show faster reduction of STO estimator variance with a double-slope line in the logvariance line versus signal-to-noise ratio (SNR) plot compared with singlepolarization (SP) counterparts, and simulations for CFO estimates show a 3-dB gain of DP over SP estimates for same SNR values defined, respectively, for quaternion-valued or complex-valued signals. Cramer-Rao bounds for STO and CFO are derived for the synchronization methods, correlating with the observed gains of DP over SP OFDM systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.7
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• pp.2154-2168
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• 2022

Our work addresses the issues associated with usage of the semantic features by Bag of Words model, which requires construction of the dictionary. Extracting the relevant features and clustering them into code book or dictionary is computationally intensive and requires large storage area. Hence we propose to use a simple distribution of multiple shape based features, which is a mixture of gradients, radius and slope angles requiring very less computational cost and storage requirements but can serve as an equivalent image representative. The experimental work conducted on PASCAL VOC 2007 dataset exhibits marginally closer performance in terms of accuracy with the Bag of Word model using Self Organizing Map for clustering and very significant computational gain.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.3
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• pp.143-150
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• 1993

To gain the basic informations on soil management practices by determination of the differences of soil genetic characteristics and the contents of soil moisture due to slope aspects of hilly land, this study was conducted at 1992 on sweet persimmon orchard soils derived from porphyry in southern of Korea. The results obtained were summarized as follows. The soils studied were belong to fine loamy family. The degree of soil development was greater in the north than other slope aspects and the solum thickness also the same. The soil chemical properties such as pH and exchangeable cations except for potassium were low generally in the orchards studied but the content of organic matter was lack in the summit and south aspect. The contents of Fe oxide and extractable Al were higher in the subsurface than surface. Fe, Al and clay indexes which indicate relative intensity of B horizon development were higher in the side slope than summit and the highest in the north slope. The rate of solum to B horizon was higher as about 1.5 for summit and west aspect which had thiner B horizon thickness compared to other aspect. North and west aspect had certainly more amount of soil water at drought season than other slope aspects and was lower the difference of soil water between the drought and wet seasons. Therfore, the soil management such as erosion control and irrigation at drought season should be practices differently due to slope aspect and soil chararteristics in the sloped land.

• Environmental and Resource Economics Review
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• v.19 no.3
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• pp.459-483
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• 2010

This paper constructs the two-part tax-a combined form of output tax and entrance fee-for polluting oligopolists under endogenous entry. In the presence of external damage that varies exogenously with aggregate output, we show that the two-part tax produces the ex post Pigouvian rule and thus achieves the first-best optimum. We also examine a detailed analysis of the impact of the two-part tax on social welfare and government revenues. Finally, when estimation errors exist in the process of regulation, we identify the incentive conflicts between interest groups and analyze the effects of estimation errors on determining optimal tax. In particular, we show that if the regulator takes care of both welfare loss and revenue gain under the proposed two-part tax, not only over-estimation on the slope of external damage but also under-estimation on the slope of market demand should be taken into the policy consideration.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.1
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• pp.44-54
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• 2001

In this paper, a novel test method is proposed to detect the hard and soft fault in analog circuits. The proposed test method makes use of the offset voltage, which is one of the op-amps characteristics. During the test mode, CUT is modified to unit gain op-amps with feedback loop. When the input of the op-amp is grounded, a good circuit has a small offset voltage, but a faulty circuit has a large offset voltage. Faults in the op-amp which cause the offset voltage exceeding predefined range of tolerance can be detected. In the proposed method, no test vector is required to be applied. Therefore the test vector generation problem is eliminated and the test time and cost is reduced. In this note, the validity of the proposed test method has been verified through the example of the dual slope A/D converter. The HSPICE simulations results affirm that the presented method assures a high fault coverage.

• Journal of Korea Water Resources Association
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• v.32 no.4
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• pp.417-426
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• 1999

A series of numerical experiments is performed to compare the characteristics of outflow hydrograph using linear and nonlinear Muskingum-Cunge methods for two cases: (a) sinusoidal inflow hydrographs and (b) rainfall inputs. The nonlinear method shows the steepening of the rising limb, coupled with a corresponding flattening of the receding limb. The linear method conserves mass exactly. In contrast, the nonlinear method is subject to a gain and a loss of mass. The loss of mass and the subsidence of peak outflow increases with a mild slope, a small baseflow $q_b$ and a large peak inflow to baseflow ratio $q_p/q_b$. A shock wave and associated numerical instability results in the increase of mass for a steep slope and a large $q_p/q_b$ ratio. While the linear method depends on the reference flow per unit-width, the nonlinear method depends on a baseflow and the $q_p/q_b$ ratio. It is found that, unlike for the sinusoidal inflow, the outflow for the rainfall inputs conserves mass fairly exactly in the nonlinear method.

• Proceedings of the KSRS Conference
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• 2009.03a
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• pp.354-359
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• 2009

Land cover types of Hustai National Park (HNP) in Mongolia, a hotspot area with rare species, were classified and their temporal changes were evaluated using Landsat MSS TM/ETM data between 1994 and 2000. Maximum likelihood classification analysis showed an overall accuracy of 88.0% and 85.0% for the 1994 and 2000 images, respectively. Kappa coefficients associated with the classification were resulted to 0.85 for 1994 and 0.82 for 2000 image. Land cover types revealed significant temporal changes in the classification maps between 1994 and 2000. The area has increased considerably by $166.5km^2$ for mountain steppe. By contrast, agricultural areas and degraded areas affected by human being activity were decreased by $46.1km^2$ and $194.8km^2$ over the six year span, respectively. These areas were replaced by mountain steppe area. Specifically, forest area was noticeably fragmented, accompanied by the decrease of $\sim400$ ha. The forest area revealed a pattern with systematic gain and loss associated with the specific phenomenon called as forest free-south slope. We discussed the potential environmental conditions responsible for the systematic pattern and addressed other biological impacts by outbreaks of forest pests and ungulates.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.3
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• pp.396-403
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• 2016

The aim was to determine the relative bioavailability of phosphorus (P) in peas for 21-day old broiler chickens using slope-ratio assay. One hundred and sixty eight male Ross 308 broiler chicks were divided into 42 groups 4 balanced for body weight and fed 7 diets in a completely randomized design (6 groups/diet) from day 1 to 21 of age. The diets were a corn-soybean meal basal diet, and the corn-soybean meal basal diet to which monosodium phosphate, brown- or yellow-seeded pea was added at the expense of cornstarch to supply 0.5% or 1% total phosphorus. Monosodium phosphate was included as a reference, and hence the estimated bioavailability of P in pea cultivars was relative to that in the monosodium phosphate. Birds and feed were weighed weekly and on d 21 they were killed to obtain tibia. The brown-seeded pea contained 23.4% crude protein, 0.47% P, whereas the yellow-seeded pea contained 24.3% crude protein and 0.38% P. Increasing dietary P supply improved (p<0.05) chick body weight gain and tibia ash and bone density. The estimated relative bioavailability of p values for brown- and yellow-seeded peas obtained using final body weight, average daily gain, tibia ash, and bone mineral density were 31.5% and 36.2%, 35.6% and 37.3%, 23.0% and 5.60%, and 40.3% and 30.3%, respectively. The estimated relative bioavailability of p values for brown- and yellow-seeded peas did not differ within each of the response criteria measured in this study. In conclusion, the relative bioavailability of P in pea did not differ depending on the cultivar (brown- vs yellow-seed). However, the relative bioavailability of P in pea may vary depending on the response criterion used to measure the bioavailability.