• Wind and Structures
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• 제30권3호
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• pp.275-288
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• 2020

High-rise buildings are very slender and flexible. Their low stiffness values make them vulnerable to horizontal loads, such as those associated with wind or earthquakes. For high-rise buildings, the threat to serviceability caused by wind-induced vibration is an important problem. To estimate the serviceability under wind action, the response acceleration of a building at the roof height is used. The response acceleration is estimated by the same wind speed at all wind directions. In general, the effect of wind direction is not considered. Therefore, the response accelerations obtained are conservative. If buildings have typical plans and strong winds blow from relatively constant wind directions, it is necessary to account for the wind direction to estimate the response accelerations. This paper presents three methods of evaluating the response accelerations while considering the effects of wind direction. These three serviceability evaluation methods were estimated by combining the wind directional frequency data obtained from a weather station with the results of a response analysis using wind tunnel tests. Finally, the decrease in the efficiencies of the response acceleration for each serviceability evaluation method was investigated by comparing the response acceleration for the three methods accounting for wind direction with the response acceleration in which wind direction was not considered.

• International Journal of Safety
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• 제11권2호
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• pp.10-14
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• 2012

Recently, the combined power plants are refocused rapidly as a replaceable energy system of the nuclear power plant. The large turbine is revolved highly at 1800~3600 rpm. Thus, the turbine speed should be monitored with mechanical and electrical method for a safety. The electrical cutoff valve which blocks the flow channel with the electrical signal is with a built in. The aim of this study is to develop a manufacturing technology through by the localization of a solenoid actuated directional control valve. Especially the results show performances of the solenoid valve by the experiments and modeling and the reliability estimation. Applied load port pressure was changed rapidly on the form of a quadratic curve over time. And in the cases of square waveform when 0~100 V and 20~120 V input voltage, it was driven on a stable state until 13.4 Hz and 16.6 Hz, respectively. We think that this study will give useful data for the electricity safety system of the combined power plant gas turbine.

• 전자공학회논문지
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• 제52권4호
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• pp.9-16
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• 2015

VANET에서 신속하고 안전한 메시지 전달은 중요한 연구 주제이다. 대부분의 연구가 운전자의 안전성을 높이기 위해 차량 간 주기적인 비콘(Beacon) 브로드캐스트를 가정하고 있다. 본 논문에서는 차량 간 통신에서 이러한 문제점을 해결하고 신뢰성 있는 데이터 전송을 지원하기 위하여 고속으로 이동하는 차량의 주행 환경에 적합한 위치기반 클러스터링을 통한 매체접속제어 프로토콜을 설계하였다. 클러스터 헤드를 통해 각 노드들의 access를 관리하고 자원을 할당함으로써 기존 싱글 채널을 사용하여 경쟁 기반의 MAC 프로토콜에서 발생하는 패킷 충돌 및 통신 지연을 줄이는 것을 시뮬레이션을 통해 확인 하였다.

• ETRI Journal
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• 제31권4호
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• pp.438-447
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• 2009

In this paper, a novel image projection technique for face recognition application is proposed which is based on linear discriminant analysis (LDA) combined with the relevance-weighted (RW) method. The projection is performed through 2-directional and 2-dimensional LDA, or $(2D)^2$LDA, which simultaneously works in row and column directions to solve the small sample size problem. Moreover, a weighted discriminant hyperplane is used in the between-class scatter matrix, and an RW method is used in the within-class scatter matrix to weigh the information to resolve confusable data in these classes. This technique is called the relevance-weighted $(2D)^2$LDA, or RW$(2D)^2$LDA, which is used for a more accurate discriminant decision than that produced by the conventional LDA or 2DLDA. The proposed technique has been successfully tested on four face databases. Experimental results indicate that the proposed RW$(2D)^2$LDA algorithm is more computationally efficient than the conventional algorithms because it has fewer features and faster times. It can also improve performance and has a maximum recognition rate of over 97%.

• 한국지역사회생활과학회지
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• 제19권4호
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• pp.569-580
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• 2008

The purpose of this study is to investigate opposites acquisition and tendency of processing negations about directional oppositionality from 3- to 6-old Korean children. The data were collected from 80 children from a daycare center and 20 university students in Busan, Korea. In Experiment 1, participants were asked to produce opposites for common terms related to colors, directions, and dimension adjectives. In Experiment 2, they were asked to make pictures corresponding to statements with negations(e. g. The arrow is NOT pointing up.). Summarizing the overall results, first, children over 5 considered 'blue' and 'red' as opposites colors in the case of not well-known color opposites. If there exists an opposite color, color opposites have been acquired from 6 year-olds, the directional opposites started from 3 year-olds, and the opposites of dimension adjectives did from 5 year-olds. Second, preferring the antipodal color opposites started from 6 and preferring the antipodal direction did from 3. Consequently, 3-to 6 year-old children acquired opposites at different age and opposites dimension. Also the opposites dimension have an effect on processing negation of young children.

• Structural Engineering and Mechanics
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• 제57권6호
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• pp.1015-1038
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• 2016

In the current research an advanced criterion with non-associated flow rule (non-AFR) for depicting the behavior of anisotropic sheet metals is presented to consider the strength differential effects (SDEs) for these materials. Owing to the fact that Lou et al. (2013) yield function is dependent on structure of an anisotropic material (BCC, FCC and HCP), an advanced yield function with inspiring of Yoon et al. (2014) yield function is proposed which is dependent upon anisotropic structures. Furthermore, to compute Lankford coefficients, a new pressure sensitive plastic potential function which would be dependent to anisotropic structure is presented and coupled with the proposed yield function with employing a non-AFR in a novel criterion which is called here 'dvanced criterion'. Totally eighteen experimental data are required to calibrate the criterion contained of directional tensile and compressive yield stresses for the yield function and directional Lankford coefficients for the plastic potential function. To verify the criterion, three anisotropic sheet metals with different structures are taken as case studies such as Al 2008-T4 (a BCC material), Al 2090-T3 (a FCC material) and AZ31 (a HCP material).

• Wind and Structures
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• 제11권6호
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• pp.427-440
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• 2008

Estimates of wind-induced wind effects on tall buildings are based largely on 1980s technology. Such estimates can vary significantly depending upon the wind engineering laboratory producing them. We describe an efficient database-assisted design (DAD) procedure allowing the realistic estimation of wind-induced internal forces with any mean recurrence interval in any individual member. The procedure makes use of (a) time series of directional aerodynamic pressures recorded simultaneously at typically hundreds of ports on the building surface, (b) directional wind climatological data, (c) micrometeorological modeling of ratios between wind speeds in open exposure and mean wind speeds at the top of the building, (d) a physically and probabilistically realistic aerodynamic/climatological interfacing model, and (e) modern computational resources for calculating internal forces and demand-to-capacity ratios for each member being designed. The procedure is applicable to tall buildings not susceptible to aeroelastic effects, and with sufficiently large dimensions to allow placement of the requisite pressure measurement tubes. The paper then addresses the issue of accounting explicitly for uncertainties in the factors that determine wind effects. Unlike for routine structures, for which simplifications inherent in standard provisions are acceptable, for tall buildings these uncertainties need to be considered with care, since over-simplified reliability estimates could defeat the purpose of ad-hoc wind tunnel tests.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제13권2호
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• pp.106-115
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• 2013

LED lighting control system using unidirectional DMX512 (digital multiplex with 512 pieces of information)) protocol has been the most popular. Nowadays, the user's consumption has been upgrading to the more intelligent system but the upgrading process does not affect the existing infrastructure. There were many researches use the additional communication for the feedback communication way such as WiFi, Controller Area Network (CAN), Power Line Communication (PLC), etc but all researches had inherent disadvantages that created the independent feedback with the existing DMX512 system. Our paper represents the novel method that uses the remote device management (RDM) protocol to associate the additional feedback with existent DMX512 infrastructure in the one system. The data in DMX512 frame sending to the DMX512 client is split and repacked to become the RDM packet. This RDM packet is transferred to the RDM monitor console and the response RDM packet is converted to the DMX512 frame for control DMX512 client devices. This is the closed loop control model which uses the bidirectional convertibility between RDM packet and DMX512 frame. The proposed method not only upgrades the feedback control function for the old DMX512 system without changing the existent infrastructure, but also solves compatible problems between new RDM devices and old DMX512 devices and gives the low cost solution for extending DMX512 universe.

• 한국해안해양공학회지
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• 제7권3호
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• pp.257-264
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• 1995

파와 해류가 동시에 작용할 때 소류사 이동에 미치는 제 요인을 파악하고, 합성류 소류사량 산정을 위하여 이들 제 요인 중 평균마찰력과 최대마찰력을 모두 고려하기 위하여 하천 소류사량 산정식들 중 적절한 형식 몇가지를 선택하였다. 합성류에 의한 최대마찰력과 평균마찰력의 산정을 위하여 BYO 모형을 적용하였으며, 일방향흐름 마찰계수 산정식은 수정 Keulegan식을 사용하였고 등가조고는 일방향흐름 관측결과와 일치하는 마찰력이 산정되는 수치를 택하였다. 각 소류사량 산정식에 도입된 비례상수는 Bijker(1966)의 수조관측자료에 적용하여 결정하였으며, 최종 결과로부터 각 산정식을 비교하여 논하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.385-385
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• 2012

A two terminal N+/P/N+ junction device to replace the conventional selective transistor was studied as a bilateral switching device for spin transfer torque (STT) MRAM based on 3D device simulation. An N+/P/N+ junction structure with $30{\times}30nm$ area requires bi-directional current flow enough to write a data by a drain induced barrier lowering (DIBL) under a reverse bias at N+/P (or P/N+ junction), and high current on/off ratio of 106. The SiGe materials are widely used in hetero-junction bipolar transistors, bipolar compensation metal-oxide semiconductors (BiCMOS) since the band gap of SiGe materials can be controlled by changing the fraction and the strain epilayers, and the drift mobility is increased with the increasing Ge content. In this work, N+/P/N+ SiGe material based junction provides that drive current is increased from 40 to $130{\mu}A$ by increased Ge content from 10~80%. When Ge content is about 20%, the drive current density of SiGe device substantially increased to 2~3 times better than Si-based junction device in case of 28 nm P length, which is sufficient current to operation of STT-MRAM.