• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권11호
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• pp.4203-4223
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• 2021

Accelerated by the Internet of Things (IoT), the need for further technical innovations and developments within wireless communications beyond the fifth generation (B5G) networks is up-and-coming in the past few years. High altitude platform station (HAPS) communication is expected to achieve such high levels that, with high data transfer rates and low latency, millions of devices and applications can work seamlessly. The HAPS has emerged as an indispensable component of next-generations of wireless networks, which will therefore play an important role in promoting massive IoT interconnectivity with 6G. The performance of communication and key technology mainly depend on the characteristic of channel, thus we propose an efficient Markov chain based channel model, then analyze the HAPS communication system's uplink capability and swing effect through experiments. According to the simulation results, the efficacy of the proposed scheme is proven to meet the requirements of ubiquitous connectivity in future IoT enabled by 6G.

• 멤브레인
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• 제4권1호
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• pp.1-8
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• 1994

There are growing needs to produce relatively high purity(99.0% or higher) oxygen at low cost. For small scale production, both pressure swing adsorption(PSA) and membrane process are competitive and less expensive or more convenient than well known cryogenic fractionation technology. A continuous membrane column(CMC) combined with a PSA oxygen generator can be employed to produce high purity oxygen continuously. The oxygen enriched gas generated by a PSA unit, with a concentration of 93~94%, is fed to the CMC that consism of three modules of poly(imide) hollow fibers. Several experiments were conducted by varying parameters, such as feed flow rate, transmembrane pressure drop, stage cut, and feed location in order to obtain a high oxygen concentration above 99.0%. A two-series unit mode was also employed with CMC operation to optimize the given membrane area.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.759-766
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• 2003

The amount of container freight continuously has been increased. and the low efficiency of container crane causes jamming frequently in transportation and cargo handling at port. The conventional control techniques based on a mathematical model are not well suited for dealing with ill-defined and uncertain systems. Recently. Fuzzy control has been successfully applied to a wide variety of practical problems as robots. automatic train operation system. etc. In this paper. a fuzzy controller for container crane is proposed to accomplish a design of improved control system for minimizing the swing motion at destination. In this scheme a mathematical model for the system is obtained in state space form. Finally. to exhibit the tracking performance and robustness of the proposed controller. computer simulations were carried out with various references, parameter variations and disturbances.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.167-168
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• 2000

We propose a signaling circuit that can reduce power consumption and Electromagnetic Interference (EMI) in a Liquid Crystal Display (LCD) controller-to-source driver interface. The proposed signaling circuit consists of a coder/decoder that can minimize temporal bit transitions in a transmission line and a current-mode driver that can convert voltage swing into a very small amount of current. We have simulated the proposed signaling circuit using the HSPICE and the proposed signaling circuit has been designed in a 0.25 ${\mu}m$ CMOS technology.

• 한국막학회:학술대회논문집
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• 한국막학회 1994년도 심포지움시리즈 Jan-94 기체분리막 기술 및 응용
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• pp.1-21
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• 1994

There are growing needs to produce relatively high purity (99.0% or higher) oxygen at low cost. For small scale production, both pressure swing adsorption (PSA) and membrane process are competitve and less expensive or more convient than well known crygenic fractionation technology. A continuous membrane colume (CMC) combined with a PSA oxygen generator can be employed to produce high purity oxygen continuosly. The oxygen-enriched gas generated by a PSA unit, with a concentration of 93-94%, is fed to the CMC that consists of three modules of poly(imide) hollow fibers. Several experiments were conducted by varying parameters, such feed flow rate, transmenbrane pressure drop, stage cut, and feed location in order to obtain a high oxygen concentration above 99.0%. A two-series unit mode was also employed with CMC operation to optimize the given membrane area.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권6호
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• pp.847-853
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• 2016

Applications of Si have been increasingly exploited and extended to More-Moore, More-than-Moore, and beyond-CMOS approaches. Ge is regarded as one of the supplements for Si owing to its higher carrier mobilities and peculiar band structure, facilitating both advanced and optical applications. As an emerging metal-oxide device, the junctionless field-effect transistor (JLFET) has drawn considerable attention because of its simple process, less performance fluctuation, and stronger immunity against short-channel effects due to the absence of anisotype junctions. In this study, we investigated lateral field scalability, which is equivalent to channel-length scaling, in Si and Ge JLFETs. Through this, we can determine the usability of Si CMOS and hypothesize its replacement by Ge. For simulations with high accuracy, we performed rigorous modeling for ${\mu}_n$ and ${\mu}_p$ of Ge, which has seldom been reported. Although Ge has much higher ${\mu}_n$ and ${\mu}_p$ than Si, its saturation velocity ($v_{sat}$) is a more determining factor for maximum $I_{on}$. Thus, there is still room for pushing More-Moore technology because Si and Ge have a slight difference in $v_{sat}$. We compared both p- and n-type JLFETs in terms of $I_{on}$, $I_{off}$, $I_{on}/I_{off}$, and swing with the same channel doping and channel length/thickness. $I_{on}/I_{off}$ is inherently low for Ge but is invariant with $V_{DS}$. It is estimated that More-Moore approach can be further driven if Si is mounted on a JLFET until Ge has a strong possibility to replace Si for both p- and n-type devices for ultra-low-power applications.

• 대한기계학회논문집B
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• 제41권8호
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• pp.505-510
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• 2017

본 논문에서는 다양한 견관절 장애 증상에 적용할 수 있는 보급형 상지 재활 로봇의 설계를 다룬다. 견관절의 회전에 수반되는 관절 중심의 위치변화를 추종하고, 사용자의 상지와 장치의 무게를 상쇄하는 3자유도 견관절 추종 및 중력보상 메커니즘을 구현하였다. 다양한 방향의 어깨 재활 동작을 구현할 수 있도록 구동축의 방향을 변환하는 메커니즘을 설계하여, 견관절에 대한 구동기의 상대적인 오리엔테이션을 변화시킴으로써 대표적인 5가지 견관절 동작을 수행할 수 있었다. 동시에 재활 운동 중의 견관절의 위치 변화를 추종하여 자연스러운 견관절 운동을 구현할 수 있었다. 최소의 구동기를 사용하는 보급형 로봇으로도 다양한 견관절 질환에 효과적으로 대응할 수 있음을 확인하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권2호
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• pp.163-168
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• 2014

Bottom gate thin-film transistors were fabricated using solution processed IGZO channel layers with various gallium composition ratios that were annealed on a hot plate. Increasing the gallium ratio from 0.1 to 0.6 induced a threshold voltage shift in the electrical characteristics, whereas the molar ratio of In:Zn was fixed to 1:1. Among the devices, the IGZO-TFTs with gallium ratios of 0.4 and 0.5 exhibited suitable switching characteristics with low off-current and low SS values. The IGZO-TFTs prepared from IGZO films with a gallium ratio of 0.4 showed a mobility, on/off current ratio, threshold voltage, and subthreshold swing value of $0.1135cm^2/V{\cdot}s$, ${\sim}10^6$, 0.8 V, and 0.69 V/dec, respectively. IGZO-TFTs annealed at $300^{\circ}C$, $350^{\circ}C$, and $400^{\circ}C$ were also fabricated. Annealing at lower temperatures induced a positive shift in the threshold voltage and produced inferior electrical properties.

• 전자공학회논문지SC
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• 제38권2호
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• pp.50-55
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• 2001

저 전력을 소모하는 새로운 방식의 논리회로를 설계하여 이의 성능실험을 위해 패리티체커를 구성하여 시뮬레이션 하였다. 기존의 저전력 소모용으로 설계된 논리회로(CPL, DPL, CCPL 등)들은 패스 트랜지스터를 통과하면서 약해진 신호를 풀 스윙 시키기 위해서 인버터를 사용하는데, 이 인버터가 전력소모의 주원인이 되고 있음이 본 논문에서 시뮬레이션 결과 밝혀졌다. 따라서 본 본문에서는 인버터를 사용하지 않고 신호를 풀스윙 시킬 수 있는 회로를 고안하였다. 기존의 CCPL게이트로 구성한 패리티체커에 비해 본 논문에서 제안한 게이트로 구성된 것이 33%의 전력을 적게 소모하는 것으로 시뮬레이션 결과 나타났다.

• 한국전기전자재료학회논문지
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• 제26권8호
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• pp.575-581
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• 2013

The self-cascode (SC) structure has low output voltage swing and high output resistance. In order to implement a simple and better SC structure, the native-$V_{th}$ MOSFETs which has low threshold voltage($V_{th}$) is applied. The proposed SC structure is designed using a qualified industry standard $0.18-{\mu}m$ CMOS technology. Measurement results show that the proposed SC structure has higher transconductance as well as output resistance than single MOSFET. In addition, analog building blocks (e.g. current mirror, basic amplifier circuits) with the proposed SC structure are investigated using by Cadence Spectre simulator. Simulation results show improved electrical performances.