• Journal of the Korean Geographical Society
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• v.46 no.6
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• pp.673-692
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• 2011

Advances in computer technology have enabled us to develop and use numerical landscape evolution models (NLEMs) for exploring the dynamics of geomorphic system from a variety of viewpoints which previously could have not been taken. However, as of yet there have been no trials using or developing NLEMs in Korea. The purpose of this research is to develop a 2 dimensional NLEM on a geological time scale and evaluate its usefulness. The newly developed NLEM (ND-NLEM) treats bedrock weathering as one of the major geomorphic processes and attempts to simulate the thickness of soil. As such it is possible to model the weathering-limited as well as the transport-limited environment on hillslopes. Moreover the ND-NLEM includes not only slow and continuous mass transport like soil creep, but also rapid and discrete mass transport like landslides. Bedrock incision is simulated in the ND-NLEM where fluvial transport capacity is large enough to move all channel bed loads, such that ND-NLEM can model the detachment-limited environment. Furthermore the ND-NLEM adopts the D-infinity algorithm when routing flows in the model domain, so it reduces distortion due to the use of the steepest descent slope flow direction algorithm. In the experiments to evaluate the usefulness of the ND-NLEM, characteristics of the channel network observed from the model results were similar to those of the case study area for comparison, and the hypsometry curve log during the experiment showed rational evidence of landscape evolution. Therefore, the ND-NLEM is shown to be useful for simulating landscape evolution on a geological time scale.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.29-42
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• 1999

The SASW (Spectral-Analysis-of-Surface-Waves) method, which evaluates the stiffness structure of the subsurface and structures nonintrusively and nondestructively, has been successfully used in the civil engineering applications. However, the SASW method assumes that the subsurface or structures consist of horizontal multi-layers, so that the method has some difficulty in continuously evaluating the integrity of a tunnel lining and a pavement system. This difficulty prevents the SASW method from being used to generate a tomographic image of stiffness for the subsurface or structures. Recently, the GPR technique which has the advantage of continuously evaluating integrity of the subsurface and structures has been popular. This advantage of GPR technique initiated the efforts to make the SASW method, which is superior to GPR and other nondestructive testing methods due to its capability of evaluating stiffness and modulus, be able to do continuous evaluation of stiffness structure, and the efforts finally lead to the development of \ulcornerTomographic SASW Technique.\ulcorner Tomographic SASW technique is a variation of the SASW method, and can generate a tomographic image of stiffness structure along the measurement line. The tomographic SASW technique was applied to the investigation of lateral variability of a sand box placed by the raining method for the purpose of verifying its effectiveness. Tomographic SASW measurements on the sand box revealed that the investigated sand box has different shear stiffness along the measurement line, which gave a clue of how to make a better raining device.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.18 no.1
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• pp.42-63
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• 1992

In order to investigate the effect of nonionic surfactants on the antimicrobial activity of preservatives in the presence and absence of p.0.E(20) Sorbitan fatty acid ester commonly used in cosmetics and pharmaceutical systems, these experiments were carried out by determining Minimum Inhibitory Concentration(MIC) values and MIC values of adaptation against test organisms. And also the inactivation of the preservative against each microorganism in formula added with various concentrations of P.0.E(20) Sorbitan monostearate were measured by use of a preservative death time curve The results obtained were as fort low : 1) Nonionic surfactant inactivated Methylparaben to varying extents, but not Imidazolidinyl urea. 2) A combined preservative system was inactivated to a little extent (range of 0.16-0.20% Conc.), no adaptation was observed for the 5. aureus ATCC 6538. Imidazolidinyl urea complex combined with Methylparaben had a broad antibacterial spectrum against the Gram(.) and the Gram(-) bacteria It was found that preservatives had a synergistic effect by use of mixed form of preservatives, 3) In formula preserved with 0.2% Methylparaben containing 0.5, 1.0 and 2.0% P.0.E(20) Sorbitan monostearate, E. coli ATCC 10s36 and P. aeruginosa NCTC 10490 died quickly within in 2hr 4) However, from Fig.5, S. aereus ATCC 6538 died more slowly within increasing surfactant concentration and the D-values(Decimal reduction time) were 5.2, 8 and 14 hr. for samples containing 0.5, 1 0 and 2.0% P 0. E(20) Sorbitan monostearate, respectively. 5) In the case of Methylparaben, no adaptation for the E. coli ATCC 10536 6) All of the nonionic surfactant, p.0. E(20) Sorbitan fatty acid ester used in the experiments decreased the effectiveness of Methylparaben, but not of Imidazolidinyl urea.

• Journal of Plant Biology
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• v.28 no.2
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• pp.165-175
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• 1985

The natural forest vegetation of the Piagol, Mt. Chiri, was classified into five major communities, i.e. Quercus mongolica, Carpinus laxiflora, C. tschonoskii, Q. serrata and Fraxinus mandshurica community. C. tschonoskii, C. laxiflora and Q. mongolica characteristically were dominated in the range of 500∼700 m, 700∼900 m and 900∼1,400 m in altitude, respectively. Abies nephrolepis and Rhododendron schlippenbachii in the ridge of Nogodan-Nalnaribong, and F. mandshurica and Q. serrata in the Yongsuam ravine were found as the dominant species. The transition between C. tschonoskii and C. laxiflora communities was relatively wide. The boundary between F. mandshurica, in the conglomerated zone, and the other communities surrounding its community was fairly abrupt. In Q. mongolica community, the canopy was relatively opened and the oak young tree of undergrowth was fairly dense. In the community of C. laxiflora and C. tschonoskii, the species composed of their understory was rich while their coverage was lower than that of Q. mongolica community. Shannon's diversity index was decreased in order of C. tschonoskii, C. laxiflora and Q. mongolica community, while their Simpson's dominance index increased conversely. Judging by the DBH-class distribution showing the negative exponential curve, these communities were considered as the climax forest. In Polar Ordination used samples (quadrats), the vegetation of the Piagol was divided into five groups, which was coincided with five communities classified by Braun-Blanquet system. In the ordination, the first axis and the second axis may be considered soil conditions and thermal conditions, respectively. It seems that two different methods, phytosociological method in macro level and ordination techniques in micro level, are useful for the vegetation classification.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.4 s.304
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• pp.31-38
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• 2005

In this paper, we propose the chromatic adaptation models (CAM) for the variations of the luminance levels. A chromatic adaptation model, CAM$\Delta$Y , is proposed according to the change of luminance level under the same illuminants. The proposed model is obtained by the transform the test colors of the high luminance into the corresponding colors of the low luminance. In the proposed model, the optimal coefficients are obtained from the corresponding colors data of the Breneman's experiments. In the experimental results, we confined that the chromaticity errors, $\Delta$u'v', between the predicted colors by the proposed model and the corresponding colors of the Breneman's experiments are 0.004 in u'v' chromaticity coordinates. The prediction performance of the proposed model is excellent because this error is the threshold value that two adjacent color patches can be distinguished. Additionally, we also propose equal-whiteness CCT curves (EWCs) by CAM$\Delta$Y according to the luminance levels of the surround viewing conditions. And the proposed EWCs can be used as the theoretical standard which determines the reference white of the color display devices.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.4
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• pp.11-17
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• 2001

In this paper, we propose a polarity decision carrier recovery algorithm for high order QAM(Quadrature Amplitude Modulation), which has robust and large frequency acquisition performance in the high order QAM modem. The proposed polarity decision PD(Phase Detector) output and its variance characteristic are mathematically derived and the simulation results are compared with conventional DD(Decision-Directed) method. While the conventional DD algorithm has linear range of $3.5^{\circ}{\sim}3.5^{\circ}$, the proposed polarity decision PD algorithm has linear range as large as $-36^{\circ}{\sim}36^{\circ}$ at ${\gamma}-17.9$. The conventional DD algorithm can only acquire offsets less than ${\pm}10\;KHz$ in the case of the 256 QAM while an analog front-end circuit generally can reduce the carrier-frequency offset down to only ${\pm}100\;KHz$. Thus, in this case additional AFC or phase detection circuit for carrier recovery is required. But by adopting the proposed polarity decision algorithm, we can find the system can acquire up to ${\pm}300\;KHz$at SNR = 30dB without aided circuit.

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.199-207
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• 2008

Wavelength converting devices with a ridge-type waveguide in periodically poled $MgO:LiNbO_3$ are made and characterized. The experimental results are compared with theoretical analysis on the effects of waveguide dimension and duty ratio of the periodically poled structure. To show the relationship of the conversion efficiency to those factors, a new measurement system is configured. That experimental results show that the center wavelength, normalized conversion efficiency and full width half maximum of the conversion efficiency curve are 1067.45 nm, 90.7%/$Wcm^2$ and 0.17 nm, respectively. Also, the estimated results of the duty period and full width half maximum of the conversion efficiency from theoretical calculations agreed well with experimental results with the errors of 0.016 ${\mu}m$ and 0.01 nm.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.1-8
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• 2010

The Fourier series uses a vibrating wave that possesses an amplitude that is like the one of the sine curve. Therefore, the functions used in the Fourier series do not change due to the value of the frequency and that set a limit to express irregular signals with rapid oscillations or with discontinuities in localized regions. However, the wavelet series analysis(WSA) method supplements these limits of the Fourier series by a linear combination of a suitable number of wavelets. By using the wavelet that is focused on time, it is able to give changes to the range in the cycle. Also, this enables to express a signal more efficiently that has singular configuration and that is flowing. The main objective of this study is to propose a scheme called wavelet series analysis for the application of wavelet theory to one-dimensional problems represented by the second-order elliptic equation and to evaluate theperformance of proposed scheme comparing with the finite element analysis. After a through evaluation of different types of wavelets, the HAT wavelet system is chosen as a wavelet function as well as a scaling function. It can be stated that the WSA method is as efficient as the FEA method in the case of axial bars with distributed loads, but the WSA method is more accurate than the FEA method at the singular points and its computation time is less.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.259-262
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• 2005

Ground resistance measurement is an elementary technique for the evaluation of grounding system. There are main environmental factors to consider for correct measurement but the problem is that it is practically most cases to measure ground resistance unable to know the factors. This paper presents a methodology toward true value of resistance in the unknown circumstances, utilizing the defined term 'variation rate' of potential difference curve appearing in the distance to a current probe as in the three point fall-of-potential method which comprises the characteristics of environmental factors. This methodology is a induced result from the previous demostrated studies.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.5
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• pp.64-72
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• 2008

The purpose of this study is to compare a habitat suitability grid unit included within a radius of 100m and $1km^2,\;2km^2,\;4km^2$ watershed units in order to predict suitable habitats for Chungcheong province's endangered leopard species(Prionailurus bengalensis). Other developed countries have carried out habitat assessment and established management policies for species conservation using such methods as HEP(Habitat Evaluation Procedures), HSI(Habitat Suitability Index) and GAP(Gap Analysis Program), etc. In accordance with these studies, many evaluation methods for habitat conservation have been proposed in Korea, but these studies are lacking in consideration of analytic units and general application of analysis results. This study predicted leopard habitat using a logistic regression analysis according to analytic units by data from 56 location and 8 sources of environmental data, including elevation, slope, forest area, land cover, roads, water, broadleaf trees, and human habitation. Moreover, the habitat suitability assessment unit was confirmed by a model comparison process encompassing model explanation. verification, and application on a regional scale. Results showed that assessment methods that took into consideration areas in and around the location points were beneficial in predicting habitat and that the assessment unit was appropriate for a 30m grid unit including areas within a radius of 100m and a $1km^2$ watershed unit in Chungcheong Province. This study suggests a method for regional habitat conservation to complement existing conservation area selection methods, and the results are expected to be used in conservation area selection and ecosystem management policies for endangered species.