• Advances in Computational Design
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• 제5권2호
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• pp.195-207
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• 2020

The present study focuses on the application of artificial neural network (ANN) and Multiple linear Regression (MLR) analysis for developing a model to predict the unconfined compressive strength (UCS) and split tensile strength (STS) of the fiber reinforced clay stabilized with grass ash, fly ash and lime. Unconfined compressive strength and Split tensile strength are the nonlinear functions and becomes difficult for developing a predicting model. Artificial neural networks are the efficient tools for predicting models possessing non linearity and are used in the present study along with regression analysis for predicting both UCS and STS. The data required for the model was obtained by systematic experiments performed on only Kaolin clay, clay mixed with varying percentages of fly ash, grass ash, polypropylene fibers and lime as between 10-20%, 1-4%, 0-1.5% and 0-8% respectively. Further, the optimum values of the various stabilizing materials were determined from the experiments. The effect of stabilization is observed by performing compaction tests, split tensile tests and unconfined compression tests. ANN models are trained using the inputs and targets obtained from the experiments. Performance of ANN and Regression analysis is checked with statistical error of correlation coefficient (R) and both the methods predict the UCS and STS values quite well; but it is observed that ANN can predict both the values of UCS as well as STS simultaneously whereas MLR predicts the values separately. It is also observed that only STS values can be predicted efficiently by MLR.

• Journal of electromagnetic engineering and science
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• 제13권2호
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• pp.134-136
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• 2013

This paper examines various aspects of the electromagnetic responses of the ring resonator located in the transverse electromagnetic cell. In addition, an equivalent circuit for the ring resonator is proposed and analyzed based on the electromagnetic phenomenon of the resonator. The equivalent circuit was simply modeled based on the concept of magnetization. A method for achieving a wider operating bandwidth of the negative permeability is provided. The ring resonator with its resonant frequency of 13.56 MHz was designed and its characteristics were examined in terms of S-parameters, effective permeability, loss rate, bandwidth, etc. The circuit and electromagnetic simulation results show an excellent agreement as well as that of theory.

• Journal of electromagnetic engineering and science
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• 제1권1호
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• pp.43-47
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• 2001

A compact size microstrip antenna element using FR-4 substrate is proposed for use in repeater and base stations. Two stacked patches are aperture-coupled by two split feedlines. Rectangular stubs on the split feedlines are laid under the aperture and have the effect of considerably lowing the magnitude of $S_{11}$ [dB] and broadening impedance bandwidth. The designed structure has been fabricated and measured. Based on 20 dB, the return loss bandwidth is about 16.8% (1.86 GHz~2.20 GHz), which covers the frequency range assigned for IMT-2000 with a large margin. The overall dimension of the proposed antenna structure is 37 mm$\times$41 mm$\times$19mm (very compact). The antenna gain is more than 7.5 dBi over the required frequency range.

• 한국세라믹학회지
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• 제33권7호
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• pp.743-754
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• 1996

In this study (Ba1-xPbx)TiO3 was synthesized by modified oxalate process in order to prevent vaporization of PbO through low temperature synthesis climinate Cl ion reproducibly substitute Pb for by and uniformly distribute ion (Ba1-xPbx)TiO3 was synthesized by coprecipitation of lead acetate barium acetate and ammonium titanyl oxalate have been used as starting materials. The substitution of Pb for Ba was reproducibly possible synthetic temperature of perovskite structure becomes lowed as the Pb concentration increases and fine partic-les (specific surface are :7.2 cm2/g) were obtained, BaTiO3 powders calcined at 90$0^{\circ}C$ for 3 hours were cubic from in XRD analysis and as Pb content was increases evident split of tetragonal peaks could be observed The optimum conditions to synthesize (Ba,Pb)TiO3 powder are the followings ; synthesis temperature (5$^{\circ}C$)

• 한국정밀공학회지
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• 제11권2호
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• pp.32-40
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• 1994

In this study by using EMAT(electro magnetic acoustic transducer)the artificial slit is installed on 12B-SUS pipe test piece. By making 4 cycle SH-burst (EMA) incidence to 45 .deg. angle, the signal data of pulse, received from EMAT are translated into digital-signal-processing- method SSP(Split Spectrum Processing) and Deconvolution method. The main conclusions obtained are as follows; (1) the signal data received from EMAT are translated with digital signal proc- essing of SSP-method and Deconvolution-method and this method shows exellent results more than Ultrasonic testing method does; (2) noise can well be removed by SSP with signal data, and resolution and S/N ratio are advanced; (3) when used with Ultrasonic wave general stainless steel has proporties of multiscattering and reflection phenomena, but resolution is progressed by using Deconvolution method;and (4) as addition-averaging-processing mumber is increasing, the resolution and S/N ratio are improved and the satisfactory signal is obtained.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2396-2401
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• 2007

Freon CHF experiments are carried out to investigate the CHF enhancements by mixing vane shapes of spacer grids in nuclear fuel assembly. The experiments were performed for a wide range mass flux, 50$\sim}$3000 kg/$m^2s$. Three kinds of spacer grids in 5${\times}$5 rod bundles are tested: no mixing vane grids, hybrid mixing vane grids, and split mixing vane grids. The CHF performances are compared along with the data belong to the PWR operating conditions based on a water equivalence through a fluid-to-fluid modeling method. The average of the data in this range is 16.4% for 37 data of hybrid vane grid and 12.5% for 24 data of split vane. In the lower mass flux, however, the split vane grid shows slightly higher performance than the hybrid vane grid.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제11권2호
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• pp.87-95
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• 1989

하악골 과두골절의 치로에 대해서는 여러가지 술식이 문헌상 보고되었으나 어떤 특정한 술식이 모든 증례에 적용될 수는 없으므로 각 증례에 따라 방사선 사진검사와 세밀한 임상검사 및 술자의 판단등에 따라 보존적인 치료법이나 외과적 수술법이 적절하게 선택되어야 한다. 대부분의 과두골절은 보존적인 치료만으로 만족스러운 결과를 얻을 수 있으나 보존적 처치후 장기간에 걸친 술후 검사시 하악의 기능장애, 부정교합, 하악골의 이환측으로의 전위, 위관절증 및 악관절 강직등의 병발증이 나타날 수 있으므로 골편이 심하게 전위된 경우나 무치악 환자, 구치부 고경유지가 어려운 환자 및 보존적 처치후 기능장애를 초래한 골편의 부정유합이나 비유합 환자에서는 관혈적 정복술로 보다 양호한 결과를 얻을 수 있다. 저자는 하악골 과두골절시 골편전위가 비교적 심한 6증례에서 악하부 피부절개를 통해 통상의 금속선 고정법, Kirschner 금속선을 이용한 고정법을 각 1예씩 사용하였고 4예는 골절선이 비교적 높아 통상의 수술방법으로 접근이 용이하지 않아 시상골절단과 사선골절단술을 이용하여 골편정복과 고정술을 시행하여 다소의 지견을 얻어 이에 보고하는 바이다.

• 대한수학회보
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• 제41권4호
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• pp.739-777
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• 2004

An analogue of the Gram's inequality for n-inner product spaces is given. Further, a number of inequalities involving Gram's determinant are stated and proved in terms of n-inner products.

• 한국토양비료학회지
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• 제6권4호
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• pp.213-219
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• 1973

국산(國産)(진해화학제조(鎭海化學製造)) 유황(硫黃)입힌 요소(尿素)(SCU)를 TVA제(製) SCU와 METAP 및 요소분시(尿素分施)와 비교(比較)하여 IR667 (Suwon 213)의 수량(收量)과 질소영양(窒素營養)에 대(對)한 효과(效果)를 조기(早期) 및 적기재배(適期栽培)의 포장시험(圃場試驗)으로 조사(調査)하였다. 1. 국산(國産) SCU는 초기(初期) 다량(多量)의 질소용출(窒素溶出)로 요소분시(尿素分施)에 비(比)하여 수풍(收豊)이나 질소영양면(窒素營養面)에서 우월(優越)한 점(點)이 별로 없었다. 2. 요소분시(尿素分施)보다 약(約) 10%의 증수(增收)를 보인 TVA제(製) SCU는 생육전기간(生育全期間)을 통(通)해 가장 높은 고중(藁中) 질소농도(窒素濃度)를 보이며 건물생산량(乾物生産量) 또는 질소흡수집적곡선(窒素吸收集積曲線)이 가장 균형적(均衡的)인 것이었다. 3. TVA제(製) SCU는 유수형성기(幼穗形成期)에 질소농도(窒素濃度)가 특(特)히 높으며 질소농도(窒素濃度)는 $m^2$ 당립수(當粒數)와 고도(高度)로 정비례(正比例) 하였다. 4. TVA제(製) SCU만이 유수형성기(幼穗形成期)에 질소흡수속도(窒素吸收速度)가 최고(最高)에 오는 일봉식(一峰式) 흡수속도양상(吸收速度樣相)을 보였다(기타(其他)는 이봉식(二峰式)) 5. 적기재배(適期栽培)에서 요소분시(尿素分施)의 질소이용율(窒素利用率)(37.1%)보다 TVA제(製) SCU는 높았으나 (46.0%) 국산(國産) SCU는 큰 차이가 없었으며 (38.9%) 조기재배(早期栽培)는 완효성(緩效性)의 질소이용율(窒素利用率)이 요소분시(尿素分施)보다 높았다. 6. TVA제(製) SCU는 출수후(出穗後)에 질소부족(窒素不足)현상을 보여주므로 용출양상(溶出樣相)이 다른 여러가지 완효성비료(緩效性肥料)를 혼합시비(混合施肥)하는 것이 가장 현상적(現想的)일 것으로 보였다.

• Advanced Composite Materials
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• 제17권2호
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• pp.139-156
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• 2008

This study aims to characterize the dynamic tensile strength of unidirectional carbon/epoxy composites. Two different carbon/epoxy composite systems, the unidirectional T700S/2500 and TR50S/modified epoxy, are tested at the static condition and the strain rate of $100\;s^{-1}$. A high-strain-rate test was performed using a tension-type split Hopkinson bar technique with a specific fixture for specimen. The experimental results demonstrated that both tensile strength increase with strain rate, while the fracture behaviors are quite different. By the use of the rosette analysis and the strain transformation equations, the strain rate effects of material principal directions on tensile strength are investigated. It is experimentally found that the shear strain rate produces the more significant contribution to strain rate effect on dynamic tensile strength. An empirical failure criterion for characterizing the dynamic tensile strength was proposed based on the Hash-in's failure criterion. Although the proposed criterion is just the empirical formula, it is in better agreement with the experimental data and quite simple.