• The Journal of the Acoustical Society of Korea
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• v.42 no.6
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• pp.536-543
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• 2023

Speaker diarization, which labels for "who spoken when?" in speech with multiple speakers, has been studied on a deep neural network-based end-to-end method for labeling on speech overlap and optimization of speaker diarization models. Most deep neural network-based end-to-end speaker diarization systems perform multi-label classification problem that predicts the labels of all speakers spoken in each frame of speech. However, the performance of the multi-label-based model varies greatly depending on what the threshold is set to. In this paper, it is studied a speaker diarization system using single-label classification so that speaker diarization can be performed without thresholds. The proposed model estimate labels from the output of the model by converting speaker labels into a single label. To consider speaker label permutations in the training, the proposed model is used a combination of Permutation Invariant Training (PIT) loss and cross-entropy loss. In addition, how to add the residual connection structures to model is studied for effective learning of speaker diarization models with deep structures. The experiment used the Librispech database to generate and use simulated noise data for two speakers. When compared with the proposed method and baseline model using the Diarization Error Rate (DER) performance the proposed method can be labeling without threshold, and it has improved performance by about 20.7 %.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.151-154
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• 2019

국내 지상파 방송 3사는 세계최초로 2017년에 지상파 UHD 본방송 서비스를 시작하였다. 지상파 UHD 방송은 ATSC 3.0 표준 기반으로 단일주파수로 방송망을 구축할 수 있으므로 각 송신소별 커버리지 중첩지역에서 방송망을 효율적으로 설계하는 것이 필요하다. 또한, ATSC 3.0 송신 장비를 실 방송환경에서 운용하기 위해서는 H/S 와 같은 안정적인 형태로 장비가 구축되어야 한다. 본 논문에서는 2017년 수도권 UHDTV 본방송이 진행된 이후, KBS에 구축한 수도권 UHD-TVR 구축 과정과 수도권 UHDTV 방송망 분석을 위한 필드테스트 결과에 대해 살펴보고자 한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.7
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• pp.644-652
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• 2004

In this paper, we designed a cascaded microstrip lowpass filter using the lowpass filters previously proposed. The previously proposed lowpass filters have a ultra-wide stopband and prominent cutoff sharpness using the combined characteristics of slot and microstrip open stub, respectively, and they are catagorized into 2 types by the method that determining their passband characteristics. The first type is determined its passband characteristics by open stub characteristics and the second is by slot characteristics. By cascading these structures with impedance adjustment of each element, the deeper out-of-band rejection and the sharper skirt response were achieved. The fabricated cascaded lowpass filters have -3㏈ cutoff frequencies at 1.035㎓ and 1.286㎓ respectively and -20㏈ stopband is over 20㎓ for both structures.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.26-35
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• 1987

As an attempt to make the multi-objection for the line design of the rope way, the resulted formulas from the catenary curve as exact ones were summarized, and it was found out that the Kuhn-Tucker's optimality conditions and regions of the objective functions can analytically be expressed with dimensionless parameters. The Pareto's optimum solution set was analytically obtained through the objective function-the minimum relation of $W^{*}$, and $W^{*}$ is a trade-off relation. From this, The dimension of a rope and the value of an initial tension that are the standard in design of the rope way were determined. It was concluded that $V^{*}$ should become minimum, and that the ratio of the dimension of rope to the value of and initial tension become larger than superposition factor corresponding to curve AB.to curve AB.

• Journal of ILASS-Korea
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• v.16 no.1
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• pp.27-36
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• 2011

The impact force on the single and overlap region of twin spray was experimentally evaluated using visualization method in full cone type swirl nozzle spray. Visualization of spray was conducted to obtain the spray angle and breakup process. The photography/imaging technique, based on Particle Image Velocimetry (PIV) using high-speed camera, was adopted for the direct observation of droplet motion and axial velocity measurement, respectively. Droplet size was measured by Particle Motion Analyze System (PMAS). The purpose of this study is to provide fundamental information of spray characteristics, such as impact force, for higher etching factor in the practical wet etching system. It was found that the spray angle, axial velocity and impact force were increased with increasing the nozzle pressure while droplet size decreased with increasing the nozzle pressure. Droplet size increased as the distance from nozzle tip was decreased. The impact force of twin spray in the overlap region was about 63.29, 67.02, 52.41% higher than that of single spray at 40, 50 and 60 mm of nozzle pitch, respectively. Also, the nozzle pitch was one of the important factors in the twin spray characteristics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.10
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• pp.1300-1308
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• 2000

The objectives of this study was to investigate the spray characteristics of single spray and twin spray in the overlap region such as mean axial velocity, mean radial velocity, mean droplet size and probability density function of droplet size. A phase doppler anemometer was used as the measurement system for droplet size and velocity. In case of single spray, injection pressure was varied from 0.2MPa to 0.7MPa. Mean axial velocity, mean radial velocity and droplet size were decreased as the distance below nozzle tip was increased. In case of twin spray, the spray characteristics were measured by varying the distance between two nozzles from 127mm to 155mm. In the overlap region, the boundary of the overlap region was determined by obtaining the distribution of mean axial and radial velocity. Droplet size was increased as the distance from nozzle tip was increased. It was found that the distribution of droplet size for twin spray in the overlap region was different to single spray.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06b
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• pp.54-56
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• 2012

본 논문에서는 위치인식 센서기반 무인이송차량(AGV)의 이동 제어 문제를 다루고자 한다. AGV의 진행 경로를 지시하는 랜드마크를 부착할 때 사각지역(dead zone) 및 중첩 지역(overlap zone)이 존재할 경우 위치 추정 오차가 허용 범위를 크게 벗어나게 되며, 이로 인해 AGV가 오동작하는 현상이 발생한다. 이를 해결하기 위해 본 논문에서는 단일 랜드마크 대신 이웃한 2개의 랜드마크 인식을 통해 위치 추정 오차를 보정하는 방안을 제안하였다. 또한, 회전 구간에서 AGV가 방향 전환 직후 지정된 경로에 허용오차 범위 이내로 진입하도록 안쪽 바퀴와 바깥쪽 바퀴의 가속도 제어 알고리즘을 제안하였다. 본 논문에서 개발된 시스템은 화장장 시신 운구용 AGV에 적용하였다. 화장장은 기존 산업 현장에 비해 이동 공간이 협소할 뿐만 아니라 그 특성상 정밀 제어가 필요한 환경이다. 본 논문에서 제안한 방식은 모의 차량에 적용하여 그 타당성을 검증하였으며, 실제 국내 화장장에 AGV 시스템을 적용한 결과 허용오차 범위 이내에서 정상 동작함을 확인하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.1
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• pp.102-110
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• 1999

The attenuation property of active noise control system is much dependent on the locations of transducers. It is very difficult to retermine the orfunal locations of transducers analytically, because the acoustic behaviors in active noise control systems are very complex and the acoustic parameters, fluid density, corqJlex propagation, coefficients, etc., are usually unknown. In this paper, effects of positions of transducers and of distances between transducers on attenuation properties of active noise control systems is investigated via computer simulations. Tbe transfer functions between the transducers are derived using the superposition principle for computer simulations. Computer simulations show that the acoustic monopole and dipole systems for duct noise attenuation are sensitive to variations of the transducer location.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.4
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• pp.519-529
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• 1993

A spectral and power efficient modulation technique, named Compact Superposed Quadrature Amplitude Modulation (Compact-SQAM), is introduced. The performance of Compact-SQAM system, in a Linearly and nonlinearly amplified single and multicarrier environment, in the presence of additive white Gaussian noise(AWGN), intersymbol interference(ISI), timing jitter and adjacent channel interference (ACI), is experimentally analyzed via computer simulation. Various channel conditions, such as channel spacing, between the main and adjacent channels and fade depth on the desired main channel, are examined. Our result shows that Compact-SQAM, and better P(e) performance that other modems using simple Butteroworth type postdetection receive filters. Especially, Compact-SQAM modem achieves higher efficiency of frequency utilization and better P(e) performance than other modems in the severly bandlimited nonlinear multicarrier channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.441-450
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• 2015

Nowadays, many WLAN access points (APs) are deployed in hotspot areas such as shopping malls and stations. As the number of WLAN APs deployed increases, how to manage densely deployed APs in an efficient manner becomes one of the most important issues in WLANs. In this environment, uncoordinated multicast services can lead to frequent collisions due to simultaneous transmissions among APs. In this paper, we propose a multicast scheduling algorithm that can exploit simultaneous transmissions in multiple sectors and avoid redundant transmissions in dense networks. Simulation results demonstrate that the proposed scheme can reduce the multicast transmission latency compared to comparison scheduling schemes.