• 말소리와 음성과학
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• 제10권3호
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• pp.1-8
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• 2018

The vowel /o/ in Seoul Korean has been undergoing a sound change by altering the acoustic weighting of F2 and F1. Studies documented that this on-going change redefined the nature of a /o/-/u/ contrast as F2 differences rather than as F1 differences. The current study examined two cognitive factors namely executive function capacity (EF) and autistic traits, in terms of their roles in explaining who in speech community would adapt new acoustic forms of the target vowels, and who would retain the old forms. The participants, 55 college students speaking Seoul Korean, produced /o/ and /u/ vowels in isolated words; and completed three EF tasks (Digit N-Back, Stroop, and Trail-Making Task), and an Autism screening questionnaire. The relationships between speakers' cognitive task scores and their utilizations of F1 and F2 were analyzed using a series of correlation tests. Results yielded a meaningful relationship in participants' EF scores interacting with gender. Among the females, speakers with higher EF scores were better at retaining F1, which is a less informative cue for females since they utilized F2 more than they did F1 in realizing /o/ and /u/. In contrast, better EF control among male speakers was associated with more use of the new cue (F2) where males still utilized F1 as much as F2 in the production of /o/ and /u/ vowels. Taken together, individual differences in acoustic realization can be explained by individuals' cognitive abilities, and their progress in the sound change further predicts that cognitive ability influences the utilization of acoustic information which is non-primary to the speaker.

• 지질공학
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• 제7권2호
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• pp.127-137
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• 1997

현재 국내에 사용되는 토목용 벤토나이트에 대하여 점도, 팽윤도, 양이온교환용량 (CEC) 및 화학성분 등의 물리화학적 특성과, X-선 회절분석 및 적외선 분광분석을 이용하여 구성광물의 함량 및 그 특성을 비교 검토하였다. 그 결과 이들 벤토나이트의 몬모릴로나이트의 함량은 50-79%의 비교적 넓은 범위를 나타내었다. 이들은 몬모릴로나이트 함량의 증가에 따라 점도, 팽윤도, 함수량, 메칠렌불루 흡착량, 양이온 교환용량, 점토입도의 함량 등이 대체적으로 증가하는 상관관계가 나타났다. 이들 특성들간에서도 서로의 상관관계가 잘 나타나므로 간접적인 특성의 파악에 본 자료가 이용될 수 있을 것으로 생각된다. 그러나 일부 시료에서는 특성에 따라 일반적인 경향과 다른 상관관계를 나타내는데 이는 원광석중 구성광물의 특성과 제조방법에 따른 혼합물질의 차이가 기인되는 것으로 생각된다. 몬모릴로나이트의 함량이 가장 적은 시료는 토목용 벤토나이트의 역할에 요구되는 여러 물리화학적 특성도 모두 열세한 것으로 나타났다.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2479-2484
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• 2018

The filter bank multicarrier modulation (FBMC) technique is one of multicarrier modulation technique (MCM), which is mainly used to improve channel capacity of cognitive radio (CR) network and frequency spectrum access technique. The existing FBMC System contains serial to parallel converter, normal QAM modulation, Radix2 inverse FFT, parallel to serial converter and poly phase filter. It needs high area, delay and power consumption. To further reduce the area, delay and power of FBMC structure, a new clock gating technique is applied in the QAM modulation, radix2 multipath delay commutator (R2MDC) based inverse FFT and unified addition and subtraction (UAS) based FIR filter with parallel asynchronous self time adder (PASTA). The clock gating technique is mainly used to reduce the unwanted clock switching activity. The clock gating is nothing but clock signal of flip-flops is controlled by gate (i.e.) AND gate. Hence speed is high and power consumption is low. The comparison between existing QAM and proposed QAM with clock gating technique is carried out to analyze the results. Conversely, the proposed inverse R2MDC FFT with clock gating technique is compared with the existing radix2 inverse FFT. Also the comparison between existing poly phase filter and proposed UAS based FIR filter with PASTA adder is carried out to analyze the performance, area and power consumption individually. The proposed FBMC with clock gating technique offers low power and high speed than the existing FBMC structures.

• 한국해안해양공학회지
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• 제17권1호
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• pp.32-40
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• 2005

방파제 구조물에 대한 기존의 내진설계 및 내진성능검토에서는 주로 설계지진에 대하여 구조물의 변위 및 응력을 검토함으로써 지진 안전성을 평가한다. 그러나 이러한 검토가 주로 결정론적 접근방법에 의한 것으로 지진의 가장 큰 특성이라 할 수 있는 불확실성을 제대로 반영하기 어렵다. 본 연구에서는 지진발생과 지반계수의 화률론적 분포 특성을 고려한 확률론적 지진위험도 평가에 대해 연구하였다. 우선 항만구조물의 지진에 대한 구조적 취약성을 다수의 지진자료를 이용하여 평가하였고, 지진재해지도를 이용하여 해당 지역에서의 지진재해도를 산정하였으며, 이들을 조합함으로써 방파제 구조물의 확률론적 지진위험도를 평가하였다.

• Smart Structures and Systems
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• 제14권5호
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• pp.811-830
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• 2014

A numerical study has been carried out to simulate an innovative monitoring procedure to detect and localize damage in reinforced concrete beams retrofitted with carbon fiber reinforced polymer (CFRP) unidirectional laminates. The main novelty of the present simulation is its ability to conduct the electromechanical admittance monitoring technique by considerably compressing the amount of data required for damage detection and localization. A FEM simulation of electromechanical admittance-based sensing technique was employed by applying lead zirconate titanate (PZT) transducers to acquire impedance spectrum signatures. Response surface methodology (RSM) is finally adopted as a tool for solving inverse problems to estimate the location and size of damaged areas from the relationship between damage and electromechanical admittance changes computed at PZT transducer surfaces. This statistical metamodel technique allows polynomial models to be produced without requiring complicated modeling or numerous data sets after the generation of damage, leading to considerably lower cost of creating diagnostic database. Finally, a numerical example is carried out regarding a steel-reinforced concrete (RC) beam model monotonically loaded up to its failure which is also retrofitted by a CFRP laminate to verify the validity of the present metamodeling monitoring technique. The load-carrying capacity of concrete is predicted in the present paper by utilizing an Ottosen-type failure surface in order to better take into account the passive confinement behavior of retrofitted concrete material under the application of FRP laminate.

• 한국터널지하공간학회 논문집
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• 제4권4호
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• pp.319-332
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• 2002

국내 조적식 철도터널의 라이닝은 적벽돌이나 화강암의 석재블럭 또는 석축으로 구성되어 있다. 조적식라이닝은 지진하중에 대한 고려가 없이 시공이 되어 있어 지진시 거동에 대한 연구가 필요하다. 따라서 본 연구에서는 철도터널내 조적식 라이닝에 대한 물성평가 및 내진 해석기법을 개발하여 내진성능을 평가할 수 있도록 하였다. 적벽돌 조적식 라이닝은 배열이 지반조건에 따라 3~5층으로 구성 되어 있으며 벽돌과 벽돌은 모르터로 부착이 되어 있다. 본 연구에서는 조적식 라이닝의 거동분석 및 내진성능 평가를 위해 적벽돌, 횡줄눈, 종줄눈과 배면줄 눈을 각각 고려한 모형을 개발하였다. 내진해석은 구조물의 고유주기 뿐만 아니라, 지반과의 상호 작용을 고려한 전체계의 주기 등을 고려하는 응답스펙트럼해석을 실시하였다. 또한 라이닝과 지반조건변화에 따른 거동을 분석하고, 보강공법에 따른 거동을 분석하여 합리적인 보강공법을 유도하였다.

• 한국산학기술학회논문지
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• 제10권10호
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• pp.2708-2714
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• 2009

언어를 통한 의사 전달 능력이 부족한 영아나 소아들은 울음으로서 자신의 몸의 상태나 요구하는 것에 대한 의사 표시를 행한다. 이 중 중요한 것이 소아 상태를 나타내는 것인데 언어 전달 능력이 없는 소아들의 질병은 진단 시기를 놓치거나 정확한 진단 결과를 내리기 어려운 문제가 존재한다. 이를 위해 본 연구에서는 소아의 울음소리를 분석하여 몸의 어느 부위가 문제가 있는지를 판단해 내는 소아 청진 시스템을 개발하였다. 특히 본 논문에서는 울음소리의 피치, 강도 및 스펙트럼 분석을 통해 소아 선천성 심질환자에 대한 질병 진단을 수행하였다. 이를 위해 각각의 분석 요소를 통해 정상적인 아이와 소아 선천성 심질환을 앓고 있는 아이에 대한 울음소리의 비교, 분석을 수행하였다. 이와 같은 방법을 통해 의사표현 능력이 부족한 소아를 대상으로 편리하게 소아 선천성 심질환을 진단할 수 있으며 임상 자료의 추가 실험을 통해 울음소리 기반의 재택형 진단 시스템을 구축할 수 있다.

• Earthquakes and Structures
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• 제11권3호
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• pp.517-538
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• 2016

This paper presents a probabilistic fragility analysis for two groups of bridges: simply supported and integral bridges. Comparisons are based on the seismic fragility of the bridges subjected to accelerograms of two seismic sources. Three-dimensional finite-element models of the bridges were created for each set of bridge samples, considering the nonlinear behaviour of critical bridge components. When the seismic hazard in the site is controlled by a few seismic sources, it is important to quantify separately the contribution of each fault to the structure vulnerability. In this study, seismic records come from earthquakes that originated in strike-slip and reverse faulting mechanisms. The influence of the earthquake mechanism on the seismic vulnerability of the bridges was analysed by considering the displacement ductility of the piers. An in-depth parametric study was conducted to evaluate the sensitivity of the bridges' seismic responses to variations of structural parameters. The analysis showed that uncertainties related to the presence of lap splices in columns and superstructure type in terms of integral or simply supported spans should be considered in the fragility analysis of the bridge system. Finally, the fragility curves determine the conditional probabilities that a specific structural demand will reach or exceed the structural capacity by considering peak ground acceleration (PGA) and acceleration spectrum intensity (ASI). The results also show that the simply supported bridges perform consistently better from a seismic perspective than integral bridges and focal mechanism of the earthquakes plays an important role in the seismic fragility analysis of highway bridges.

• 한국정보통신학회논문지
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• 제20권3호
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• pp.484-490
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• 2016

동일 주파수에서 신호의 송신과 수신을 동시에 수행하는 전이중 통신은 무선 링크 용량을 향상시킬 기술로 관심을 받고 있지만, 노드가 전송하는 시그널이 자신에게 간섭으로 작용하는 자기간섭을 억제해야 용량 이득을 달성할 수 있다. 본 논문에서는 자기간섭 제거 기법을 구현하고 이를 SDR(Software-Defined Radio) 기반의 송수신 시스템과 결합한 테스트베드 실험을 통해 제거 성능을 측정한다. 구현된 자기간섭 제거 기법은 안테나 배치 기법과 아날로그 신호 레벨에서 노이즈를 제거하는 회로 기법으로, 안테나 배치를 통한 기법의 동작 시 안테나 위치에 따른 자기간섭 제거 게인의 변화를 측정을 통해 보이고, 이 두 기법이 동시에 적용되었을 때 추가적인 게인을 얻을 수 있음을 보인다.

• Journal of Communications and Networks
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• 제2권1호
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• pp.5-17
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• 2000

cdma2000 offers several enhancement as compared to TIA/EIA-95, although it remains fully compatible with TIA/EIA-95 systems and allows for a smooth migration from one to the other-Major new capability include:1)connectivity to GSM-MAP in addition to IP and IS-41 networks; 2) new layering with new LAC and MAC architectures for improved service multiplexing and QoS management and efficient use of radio resource ;3) new bands and band widths of operation in support of various operator need and constraints, as well as desire for a smooth and progressive migration to cdma 2000; and 4) flexible channel structure in support of multiple services with various QoS and variable transmission rates at up to 1 Mbps per channel and 2 Mbps per user. Given the phenomenal success of wireless services and desire for higher rate wireless services. improved spectrum efficiency was a major design goal in the elaboration of cdma2000. Major capacity enhancing features include; 1) turbo coding for data transmission: 2)fast forward link power control :3) forward link transmit diversity; 4) support of directive antenna transmission techniques; 5) coherent reverse link structure; and 6) enhanced access channel operation. As users increasingly rely on their cell phone at work and at home for voice and data exchange, the stand-by time and operation-time are essential parameters that can influence customer's satisfaction and service utilization. Another major goal of cdma2000 was therefore to enable manufacturers to further optimize power utilization in the terminal. Major battery life enhancing features include; 1) improved reverse link performance (i.e., reduced transmit power per information bit; 2) new common channel structure and operation ;3) quick paging channel operation; 4) reverse link gated transmission ; and 5) new MAC stated for efficient and ubiquitous idle time idle time operation. this article provides additional details on those enhancements. The intent is not to duplicate the detailed cdma2000 radio access network specification, but rather to provide some background on the new features of cdma2000 and on the qualitative improvements as compared to the TIA/EIA-95 based systems. The article is focused on the physical layer structure and associated procedures. It therefore does not cover the MAC, LAC, radio resource management [1], or any other signaling protocols in any detail. We assume some familiarity with the basic CDMA concepts used in TIA/EIA-95.