• Journal of Korea Multimedia Society
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• v.16 no.5
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• pp.637-646
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• 2013

In order to model a variety of natural trees that are appropriate to outdoor terrains consisting of multiple trees, this study proposes a modeling method of new growth rules(based on the convolution sums of divisor functions). Basically, this method uses an existing growth-volume based algorithm for efficient management of the branches and leaves that constitute a tree, as well as natural propagation of branches. The main features of this paper is to introduce the theory of convolution sums of divisor functions that is naturally expressed the growth or fate of branches and leaves at each growth step. Based on this, a method of modeling various tree is proposed to minimize user control through a number of divisor functions having generalized generation functions and modification of the growth rule. This modeling method is characterized by its consideration of both branches and leaves as well as its advantage of having a greater effect on the construction of an outdoor terrain composed of multiple trees. Natural and varied tree model creation through the proposed method was conducted, and using this, the possibility of constructing a wide nature terrain and the efficiency of the process for configuring multiple trees were evaluated experimentally.

• The Journal of the Acoustical Society of Korea
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• v.19 no.5
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• pp.79-83
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• 2000

When passband ripple α/sub p/ and stopband attenuation α/sub s/ at the w/sub s/ where the stopband begins are specified in filter design, △α/sub s/ usually exceeds the specification by △α/sub s/ due to the necessity that the order n of the filter function be an integer. In this paper, we apply a trade-off method to remove the excess stopband attenuation △α/sub s/ for reducing the value of pole-Q and improving the characteristics of the Chebyshev filter function. We also apply the trade-off method of pole-Q reduction to the modified Chebyshev function, and then the 4 types of function have been analyzed to compare in frequency and time domain characteristics. The trade-off method reduces the pole-Q which influences the filter characteristics to maximum 49.6% without increase of the order n. Thus implies that they have the improved characteristics such as the reduced passband ripple and flatter delay characteristics as compared Chebyshev filter function before trade-off. And the unit step response shows shorter delay time and settling time in time domain performance.

• Journal of the Korean Data and Information Science Society
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• v.26 no.6
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• pp.1305-1315
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• 2015

Consider the risk score which is a function of a linear score for the classification models. The AUC optimization method can be applied to estimate the coefficients of linear score. These estimates obtained by this AUC approach method are shown to be better than the maximum likelihood estimators using logistic models under the general situation which does not fit the logistic assumptions. In this work, the VUS and HUM approach methods are suggested by extending AUC approach method for more realistic discrimination and prediction worlds. Some simulation results are obtained with both various distributions of thresholds and three kinds of link functions such as logit, complementary log-log and modified logit functions. It is found that coefficient prediction results by using the VUS and HUM approach methods for multiple categorical classification are equivalent to or better than those by using logistic models with some link functions.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.105-114
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• 2004

Consolidation characteristics have been investigated by using Rowe cell consolidation tester for dredged soil, which is more than two times as much as the liquid limit. To examine the effects of variation of water content on consolidation characteristic, tests were carried out varying the initial water content from $100\%\;to\;150\%.$ The results were compared with the consolidation characteristics of remolded clay. The test results showed that the hither the initial water content of dredged clay was, the more noticeable the non-linear behavior of e-log P curves occurred. The variation of the gradient was apparent to load stage 40kPa and became less apparent after load stage 80kPa on the e-log P curves. Ratio of compression index stayed within the range suggested by Mesri and variation of initial water content has hardly influenced the coefficient of consolidation. On the contrary, it was found that the magnitude of consolidation load affects the vertical coefficient of consolidation. The variation of stratum thickness during consolidation processing needs to be taken into consideration since hydraulic fill would go through a much larger scale strain than land soil when it is subject to a load. In this study, the consolidation period considering the variation of stratum thickness was analyzed and the results were compared with those of existing consolidation studies which did not consider the variation of stratum thickness. According to the results of the study, the consolidation period of the ground with a larger strain was calculated more close to observed value in case of Mikasa theory which takes the variation of stratum thickness into consideration.

• Electrical & Electronic Materials
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• v.3 no.1
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• pp.9-19
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• 1990

본 연구에서는 산회물 혼합법, 솔-젤법, 공침법등의 세가지 방법으로 PbTiO$_{3}$분말을 제조하여 폴리머와 혼합 O-3 복합재료를 제작한 후, 하이드로폰으로의 응용을 위한 제 특성을 고찰하였다. 비유전상수는 PbTiO$_{3}$의 체적비 증가에 따라 지수함수적으로 증가하였으며 유전손실은 선형적으로 증가하였다. 수정입방체 모델로 부터 계산된 변형계수 n은 M-O, S-G, C-P의 경우 각각 0.724, 0.585, 0.483으로 나타났다. 압전 변형계수 d$_{33}$는 PbTiO$_{3}$의 체적비, 분극전장 및 분극 시간의 증가에 따라 증가하였으며 일정시간 경과후에는 포화값을 나타내었다.다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.1
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• pp.1-9
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• 1992

Eigen Function Expansion Method(EFEM) and Plane Wave Approximation are employed to study the propagation of linear water waves over trenches. The properties of trapped waves due to depth and ambient current discontinuities and the effect of evanescent modes on wave propagations are investigated. Special attention is paid to the trapped waves, and not only 3-D plots but also B-D plots of wave propagation are presented.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.413-423
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• 1991

Multiaxial loading by combinations of tension-torsion-internal pressure have been applied to the thins-walled tubular specimens prepared from cold drawn tubes of SAE 1020 steel. Prior to the multiaxial loading, each specimen has been twisted to different shear strains. Uniaxial tensile yield stresses measured at different angles to the tube axis clearly show that the initial orthotropic symmetry is maintained during twisting. The orthotropy axes are observed to rotate with shear strains. The plane stress yield locus measured for each twisted specimens show that yield surface shape does not remain similar during twisting and thus anisotropic work hardening is not a function of only plastic work.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.260-261
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• 2012

스마트 환경에 관심이 높아지면서 무선 센서 네트워크를 이용한 유비쿼터스 시스템을 실생활에 활용하려는 노력이 이어지고 있다. 무선 센서 네트워크는 무선 통신으로 정보를 수집하기 때문에 실생활에 적용할 경우 사생활 정보가 유출될 가능성을 가진다. 본 논문은 데이터 전송 과정에서 데이터가 유출되었을 때, 원본 데이터로의 해독을 어렵게 하는 해시 알고리즘을 제안한다. 제안하는 알고리즘은 단 방향 해시 함수인 MD5를 변형한 TinyMD5를 이용하여 데이터를 변환하고, MD5를 변형하면서 발생하는 해시 값 충돌 문제를 해결할 수 있는 기법을 추가하였다. 제안하는 알고리즘의 우수성을 보이기 위해 기존의 기법과 시뮬레이션을 통해 성능을 비교 평가하였다. 성능 평가 결과, 제안하는 알고리즘은 통신 에너지를 기존 알고리즘의 평균 29%만을 소모하였다.

• Journal of Welding and Joining
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• v.12 no.4
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• pp.151-161
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• 1994

FCAW has wide application in ship fabrication, maintenance and field erection. It has many advantages over SMAW.SAW and GMAW process. In many applications, the FCAW provides highquality weld metal. This method can reduce weld defects especially porosity and spatter. But the fatigue characteristics of those deposited metal have been rarely investigated. The purpose of this study is to investigate the cyclic stress-strain behavior and fatigue tests by the constant strain control were carried out on the rounded smooth specimen with deposited metal using the metal type flux cored wire. As the results of this study for the deposited metal welded by the metal type flux cored wire, the hardening or softening characteristics under cyclic load were investigated and cyclic stress-strain curve, strain-fatigue life curve, stress-strain function and fatigue life relation which are useful to estimate the fatigue life under the stress concentration condition were obtained.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.309-314
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• 2000

Rubber is used as a primary suspension component in a vehicle or a mechanical structure. The aim of this study is to establish a procedure for measuring the material properties of rubber and to analyze the differences of material properties of virgin rubber and heat aged rubber. The effect of mechanical conditioning was shown and included in the procedures of tensile. compression. simple shear. and pure shear tests. In addition. using engine oil was recommended for compression test in order not to have barrelling. Moreover, based on the material properties of vil·gin rubber and heat aged rubber. equations of C10 and IRHD were proposed as a function of heat aging temperature and time.