• International Journal of Computer Science & Network Security
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• 제23권5호
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• pp.121-127
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• 2023

A 500 km/h linear motor high speed terrestrial transportation service is planned to launch 2027 in Japan. In order to support 5G service in the train, the Sub-carrier spacing frequency of 30 kHz is planned to be used instead of common 15 kHz sub-carrier spacing to mitigate Doppler effect in such high-speed transportation. In addition, to increase the cell size of 5G mobile system, plural Base Station antenna will transmit the identical Down Link (DL) signal to form the expanded cell size along the train rail. In this situation, forward and backward antenna signals will be Doppler shifted by reverse direction respectively and the receiver in the train might suffer to estimate accurate Channel Transfer Function (CTF) for its demodulation. In this paper, Delay and Doppler Profiler (DDP) based Channel Estimator is proposed and it is successfully implemented in signal processing simulation system. Then the simulated performances are compared with the conventional Time domain linear interpolated estimator. According to the simulation results, QPSK modulation can be used even under severe channel condition such as 500 km/h, 2 path reverse Doppler Shift condition, although QPSK modulation can be used less than 200 km/h with conventional Channel estimator.

• 한국지반신소재학회논문집
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• 제11권4호
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• pp.27-35
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• 2012

국내에 적용되고 있는 블록식 보강토 옹벽의 전면벽체는 보강재의 고정 및 뒷채움재의 유실방지 역할을 하지만, 벽체에 작용하는 하중에 대한 역학적 기능은 부족하다. 보강토체를 구성하는 벽체에 휨 및 전단에 대한 저항 성능을 부여하기 위하여 개발된 강성벽 일체형 보강노반은 다양한 장점에도 불구하고, 기존 공법과 비교하여 경제성 및 시공성 측면에서 단점이 부각되어 현장에의 적용은 미루어져 왔다. 본 연구에서는 강성벽 일체형 보강노반의 국내 적용성 향상을 목적으로 강성벽의 성능은 확보하면서 경제성 및 시공성을 향상시키기 위한 보강재 연직 배치 간격 및 길이 변화가 보강토체 전체의 거동에 미치는 영향을 평가하였다. 이를 위하여 강성벽을 갖는 1/10 축소모형 보강토체 및 높이 3m의 실내 실대형 시험체를 조성하고, 모사 열차하중 하에서의 변형 특성을 평가하였다. 시험 결과 비록 짧은 보강재를 사용함에도 불구하고 강성벽 보강노반에서 벽체 수평 발생변위 및 침하는 허용한계 수준 이하이었으며, 보강재 연직 배치간격이 30cm에서 40cm로 증가하여도 사용성 측면에서의 성능 수준에는 큰 변화가 없는 것을 확인할 수 있었다.

• Journal of Korean Vacuum Science & Technology
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• 제6권2호
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• pp.79-83
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• 2002

As Ag does not form my silicide on Si surfaces, Ag wire is a candidate for self-assembled nanowire on the reconstructed and single-domain Si(5 5 12)-2 $\times$ 1. In the present study, various Ag coverages and post-annealing temperatures had been tested to fabricate a Ag nanowire with high aspect ratio. When Ag coverage was less than 0.03 ML and the post-annealing temperature was 500(C, Ag atoms preferentially adsorbed on the tetramer sites resulting in Ag wires with an inter-row spacing of ~5 nm. However, its aspect ratio is relatively small and its height is also not even. On the other hand, the Ag-posited surface completely loses its reconstruction even with the same annealing at 500 $\^{C}$ if the initial coverage exceeds 0.05 ML. But the additional subsequent annealing at 700$\^{C}$ and slow-cooling process recovers the well-ordered Ag chain with relatively high aspect ratio on the same tetramer sites. It can be understood that, in the double step annealing process, the lower temperature annealing is required for cohesion of adsorbed Ag atoms and the higher temperature annealing is for providing Ag atoms to the tetramer sites.

• Computers and Concrete
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• 제15권1호
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• pp.55-71
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• 2015

This paper presents a novel harmony search (HS)-based data-driven single input rule modules (SIRMs)-connected fuzzy inference system (FIS) for the prediction of stress in externally prestressed tendon. The proposed method attempts to extract causal relationship of a system from an input-output pairs of data even without knowing the complete physical knowledge of the system. The monotonicity property is then exploited as an additional qualitative information to obtain a meaningful SIRMs-connected FIS model. This method is then validated using results from test data of the literature. Several parameters, such as initial tendon depth to beam ratio; deviators spacing to the initial tendon depth ratio; and distance of a concentrated load from the nearest support to the effective beam span are considered. A computer simulation for estimating the stress increase in externally prestressed tendon, ${\Delta}f_{ps}$, is then reported. The contributions of this paper is two folds; (i) it contributes towards a new monotonicity-preserving data-driven FIS model in fuzzy modeling and (ii) it provides a novel solution for estimating the ${\Delta}f_{ps}$ even without a complete physical knowledge of unbonded tendons.

• 한국농촌건축학회논문집
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• 제21권1호
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• pp.37-44
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• 2019

Recently, various tourist products using hanok have increased rapidly. In the meantime, there is a steady demand for Hanok architecture. However, there are many negative perceptions about wood deformation and biodeterioration. Wood deformation and biodeterioration are related to moisture content. And the cracks occur in the process of removing water from the wood. Therefore, this study investigates the moisture content and cracks of dried hanok made of wood according to the drying method of wood. Drying methods include natural seasoning and artificial seasoning. There was a difference in moisture removal depending on drying period and method of natural seasoning. Drying time should be about 3 years for natural seasoning, so the moisture content of the wood is stable. In addition, the moisture absorption rate was low even in a humid environment where the voids were removed. However, natural seasoning is time consuming. Artificial seasoning, on the other hand, can quickly remove moisture from the wood and reduce porosity, but it is costly. Cracks that occur during the drying of wood may become problematic in appearance and stability due to wider spacing over time. As a result, the difference in the moisture content of the timber depending on the drying method and drying period of the wood was maintained even after the formation. These gaps appeared to be differences in moisture absorption in a wet environment.

• 한국지진공학회논문집
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• 제26권3호
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• pp.127-136
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• 2022

Recently, an unprecedented emerging infectious disease has rapidly spread, causing a global shortage of wards. Although various temporary beds have appeared, the supply of wards specializing in infectious diseases is required. Negative pressure isolation wards should maintain their function even after an earthquake. However, the current seismic design standards do not guarantee the negative pressure isolation wards' operational (OP) performance level. For this reason, some are not included in the design target even though they are non-structural elements that require seismic design. Also, the details of non-structural elements are usually determined during the construction phase. It is often necessary to complete the stability review and reinforcement design for non-structural elements within a short period. Against this background, enhanced performance objectives were set to guarantee the OP non-structural performance level, and a computerized tool was developed to quickly perform the seismic design of non-structural elements in the negative pressure isolation wards. This study created a spreadsheet-based computer tool that reflects the components, installation spacing, and design procedures of non-structural elements. Seismic performance review and design of the example non-structural elements were conducted using the computerized tool. The strength of some components was not sufficient, and it was reinforced. As a result, the time and effort required for strength evaluation, displacement evaluation, and reinforcement design were reduced through computerized tools.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.121-128
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• 1999

Recently, research of reinforcement mechanism in a sense of soil mechanics has been under way by many researchers with developing various kinds of geoteutiles. But it must be consider that reinforcement effect largely depends on used geotextile even if it is used on same in-site condition. As a matter of fact it is not necessarily that reinforcement effect appears in all the case of reinforced soil construction. It means that appropriate geotextile coincided with the intention has to be selected and adequate examination is needed. In this study, reinforcement effect with various kinds of geotextiles are compared through a series of direct shear tests. Based on the test results, shear strength characteristics and reinforced effects are investigated quantitatively and qualitatively considering the confining stress, reinforcement characteristics and number of reinforcement.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.167-171
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• 1995

The orientation dependence of sputtering rate in the sendust polysrystalline targets was studied, It was fount from the present work that the erosion process is not uniform from one grain to another even within a target because of its polysrystalline nature showing many different orientation of grains. The grains oriented to promote efficient erosion were characterized by the close-packed planes which have large interplanar spacing and strong binding energy, The characteristic line patterns appeared on as-sputter target surface are discussed in terms of symmetry of crystllographic planes.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.455-458
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• 1999

It has been known that buildings having inappropriate expansion joints in their spacings may be subject to exterior damages due to extensive cracks on the outer walls under service loads, and structural damages due to excessive moment induced by temperature changes at ultimate load conditions. Rather inconsistent code provisions are available regarding spacings of expansion joints from different foreign structural codes and even worse, no quantiative measure on spacings is given in our codes for building structures. In order to establish a rational measure on the spacing of expansion joints, theoretical approaches are taken in this study. The developed theoretical formula is, then, converted to design chart for structural designer's convenience in its use. The chart considers both service and ultimate load stages.

• Journal of Biosystems Engineering
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• 제20권3호
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• pp.217-225
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• 1995

This study was conducted to find design factors of spraying device of the boom sprayer for low volume application. Four types of nozzles(standard flat nozzle, drift guard nozzle, even flat nozzle, and hollow cone nozzle) were used for the spray characteristic experiment. Spray patterns of the nozzles were distinguished by the nozzle type, spray distance, and spray direction. The flow rate was proportional to the square root of spray pressure in all nozzles. Increased nozzle height improved spray distribution at reduced pressures and/or increased spacing. Distribution tended to improve as pressure increased within the range of pressures used for fan nozzles.