• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.114-124
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• 2014

HEVC is a state-of-the-art video coding standard developed by JCT-VC. HEVC provides about 2 times higher subjective coding efficiency than H.264/AVC. One of the main goal of HEVC development is to efficiently coding UHD resolution video so that HEVC is expected to be widely used for coding UHD resolution video. Decoding such high resolution video generates a large number of memory accesses, so a decoding system needs high-bandwidth for memory system and/or internal communication architecture. In order to determine such requirements, this paper presents an analysis of the memory access complexity for HEVC decoder. we first estimate the amount of memory access performed by software HEVC decoder on an embedded system and a desktop computer. Then, we present the memory bandwidth models for HEVC decoder by analyzing the data flow of HEVC decoding tools. Experimental results show the software decoder produce 6.9-40.5 GB/s of DRAM accesses. also, the analysis reveals the hardware decoder requires 2.4 GB/s of DRAM bandwidth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.761-764
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• 2010

Interest in vehicle infotainment system, that provides both entertainment of driving and information for safe and convenient driving, has been recently increased. MOST is defined as the network transmitting high-bandwidth infortainment data to vehicle, and it has been standardized as MOST150. In this research, dynamic behavior method that deals with roles and functions of each devices connected to MOST150 Network, and Power Management Method was studied. MOST Network consists of a master device, including function block 'NetworkMaster', and all other devices called slave devices. The purpose of this study is to apply the analysis of the methods of operating and power management based on condition of master device and slave devices on MOST150 network to the future development of MOST150 devices.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.37-43
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• 2018

Science DMZ is a network architecture that considers complicated network components such as dedicated network, DTN, and minimum security policy to maximize transfer efficiency. And DTN tuning is an essential component to take full advantage of Science DMZ's available bandwidth. In addition, tuning of network system should be performed concurrently to minimize packet loss due to network bottleneck. In this paper, we propose a tuning method of data transfer node and network system for maximizing transfer efficiency in Science DMZ network architecture. As a result of the performance measurement using the KREONET, the network performance after the DTN tuning shows 180% improvement than that of existing method without DTN tuning. In addition, performance of 9.4Gb/s was shown without loss of performance measurement after tuning network system applying shaping policy.

• Journal of Digital Convergence
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• v.17 no.3
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• pp.221-226
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• 2019

The characteristic of the beta wave among the EEG waves corresponds to the stress area of human perception. The over-bandwidth of the stress is extracted by analyzing the beta-wave correlation between the low-bandwidth and high-bandwidth. We present a KMeans clustering analysis model for unsupervised machine learning to construct an analytical model for analyzing and extracting the beta-wave correlation. The proposed model classifies the beta wave region into clusters of similar regions and identifies anomalous waveforms in the corresponding clustering category. The abnormal group of waveform clusters and the normal category leaving region are discriminated from the stress risk group. Using this model, it is possible to discriminate the degree of stress of the cognitive state through the EEG waveform, and it is possible to manage and apply the cognitive state of the individual.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.88-93
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• 2023

As the demand for High Bandwidth Memory (HBM) increases and the handling capability of larger wafers expands, ensuring reliable Total Thickness Variation (TTV) measurement for stacked wafers becomes essential. This study presents the design of a measurement module capable of measuring TTV across the entire area of a 300mm wafer, along with estimating potential mechanical measurement errors. The module enables full-area measurement by utilizing a center chuck and lift pin for wafer support. Modal analysis verifies the structural stability of the module, confirming that both the driving and measuring parts were designed with stiffness exceeding 100 Hz. The mechanical measurement error of the designed module was estimated, resulting in a predicted measurement error of 1.34 nm when measuring the thickness of a bonding wafer with a thickness of 1,500 ㎛.

• Journal of Navigation and Port Research
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• v.26 no.3
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• pp.289-294
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• 2002

The broadband high power 3-way combiner was designed and fabricated for the digital TV repeater. To achieve increase of the bandwidth and the high power capability, Wilkinson type power divider was adopted in our research. First of all, Wilkinson type power divider of equal-split and unequal-split were combined, and the characteristics of the four port in-phase power combiner was simulated for each thickness of dielectric substrates. As the results of simulation, the power combiner fabricated by using dielectric substrate of 120 mil-thickness has the characteristics as follows: insertion loss of less than -651 dB, reflection coefficient of less than -13 dB, isolation among the output ports of less than -15 dB, and pose difference among the output ports of smiler than 13$^{\circ}$. Therefore, this power combiner was possible to improve the limit of microstrip line width due to high impedance, the problem of power loss due to interaction between strip lines in a high power combiner and narrow bandwidth simultaneously. Furthermore, making broadband and high power could be achieved since the fabricated 3-way combiner has good characteristics of insertion loss, the reflection coefficient, separation between ports, and phase difference.

• Korean Journal of Optics and Photonics
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• v.25 no.6
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• pp.340-345
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• 2014

We experimentally demonstrate the use of a gold-deposited side-polished fiber as a $2-{\mu}m$-band polarizing device to produce mode-locked pulses from a thulium/holmium-codoped fiber ring cavity. The mode-locking effect was induced by nonlinear transmission caused by the gold-deposited side-polished fiber, due to nonlinear polarization rotation of the oscillated beam within the fiberized cavity. It is also shown that ~558-fs pulses with a peak power of ~6.7 kW could readily be produced at a wavelength of 1935 nm through subsequent thulium/holmium-codoped fiber amplification, due to the higher-order soliton compression effect.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.105
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• pp.184-192
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• 2006

Synthetic Aperture Radars(SAR) are used mainly for high-resolution imaging of the terrain. This paper describes the $16{\times}16$ array antenna designed for an X-band, automobile-based SAR(AutoSAR) system. This antenna has the structure of several layers such as radome, radiators, slots, feed network, and honeycomb cores. Each layer is adhesively bonded to meet different combination of structural and electrical design requirements. Using the Strip-Slot-Foam-Inverted-Patch(SSFIP) structure and honeycomb cores, a wide bandwidth and a structural hardness were achieved. Measurement results were compared with simulation results. It was observed that this antenna had a bandwidth of 1.7 GHz, side-lobe levels of less than -20 dB, half-power beamwidth of $5^{\circ}$ and $5^{\circ}$, and gains of 25.0 dBi. The observed results show that the designed array antenna will be applicable to the wideband SAR system.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.347-348
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• 2001

마이크로스트립 안테나가 가지는 가장 큰 단점인 협대역 특성을 개선하기 위해 그 동안 수많은 연 구와 방법들이 제안되었는데 특히 원형편파 안테나는 임피던스 대역폭 외에 축비 대역폭까지도 고려 되어야 하므로 더욱 심화된 협대역의 특성을 가지게 되어 설계에 많은 어려움이 있었다. 일반적으로 원형편파 마이크로스트립 안테나를 설계하는 방법 중 급전 구조면에서는 크게 단일 급전 방식과 하이 브리드 형태의 급전방식이 있다. 단일 급전 방식의 원형편파 안테나는 구조가 간단하고y 제작이 간편 하며, 안테나의 물리적 크기를 줄일 수 있어 배열시 장점이 있으나 구조의 특성상 협대역의 축비 대역 폭을 가지며I 하이브리드 급전 원형편파 안테나는 구조가 복잡하고, 제작이 어려우며, 안테나의 물리적 크기가 커진다는 단점이 있으나 광대역의 축비 대역폭을 가진다. 따라서 원형편파 안테나의 설계시 축 비 대역폭과 안테나의 물리적 크기 간의 trade-off를 고려하여야한다. 최근에는 이를 고려한 단일 급전 을 이용하면서도 개선된 축비특성올 얻을 수 있도록 십자개구 개구를 통해 두 개의 직교 모드를 방사 패치에 급전하는 구조가 제안되기도 하였다. 하지만 이는 일반적인 단일 급전 방식보다 개선된 축비 대역폭을 얻을 수 있었으나 중심주파수에서 2.5%에 불과하였다. 본 논문에서는 단일 급전 십자개구 결합 방식이 가지는 협대역의 축비 대역폭을 개선하기 위해 단 일 급전으로 하이브리드 급전의 효과를 가져올 수 있는 직렬 급전 십자개구 결합 마이크로스트립 안 테나를 제안하였으며, 기존에 발표된 단일 급전 십자개구 결합 안테나와의 축비 대역폭, 이득, 방사패 턴, 그리고 임피던스 대역폭 둥과 비교하여 개선된 특성을 제시하고 제안된 안테나의 타당성을 보였 다. 실제로 2.4GHz의 주파수에서 제안한 직렬 급전 십자개구 결합 단일 마이크로스트립 안테나의 측 정결과 기존에 연구된 안테나보다 약 2배정도 증가된 4.6%의 축비 대역폭, 10%의 임피던스 대역폭 (VSWR<1.5), 그리고 8.2dBi의 최대이득 특성을 확인할 수 있었으며, 이를 바탕으로 시권셜 로테이션 기법올 사용한 $2\times2$ 배열 안테나는 17.5%의 축비 대역폭, 20.8%의 임피던스 대역폭(VSWR<1.5), 그리 고 12.5dBi의 최대이득을 얻을 수 있었다. 이에 해당하는 제안된 단일 안태나와 $2\times2$ 배열 안테나의 구조, 측정된 축비 대역폭 및 이득특성, 그리고 입력 반사손실을 그림 I, 2, 3에 각각 나타내었다.

• Journal of the Korean Magnetics Society
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• v.8 no.5
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• pp.255-260
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• 1998

Fabrication condition and magnetic properties of ultrathin Co-based amorphous alloy have been investigated. When the ejection gas pressure was lower than 0.05 kgf/$\textrm{cm}^2$ at the roll speed of 55 m/s, ultrathin ribbons with the thickness less than 10 ${\mu}{\textrm}{m}$ were successfully obtained. The ribbon thickness decreased linearly with the decrease in ejection pressure. Moreover the significant decrease in ribbon width was accompanied with the decrease of thickness in the range of ejection pressure to form an ultrathin ribbon. This behavior was attributed to the decrease of effective ejection pressure in the both end-sides of rectangular nozzle due to the larger friction between molten metal and nozzle wall. The effective permeability at low frequency (1 kHz) decreased largely with the decrease in ribbon thickness, while the coercive force increased with the thickness decrease. It was considered that these behaviors were due to the enhancement of surface effect leading to the suppression of wall motion. However effective permeability at high frequency (1 MHz) increased with the decrease in ribbon thickness, and this was ascribed to the easier magnetization rotation owing to the reduction of eddy current.