• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.2
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• pp.85-90
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• 2012

In this paper, we compared and analyzed 3D silicon-oxide-nitride-oxide-silicon (SONOS) multi layer flash memory devices fabricated on nitride or oxide layer, respectively. The device fabricated on nitride layer has inferior electrical properties than that fabricated on oxide layer. However, the device on nitride layer has faster program / erase speed (P/E speed) than that on the oxide layer, although having inferior electrical performance. Afterwards, to find out the reason why the device on nitride has faster P/E speed, 1/f noise analysis of both devices is investigated. From gate bias dependance, both devices follow the mobility fluctuation model which results from the lattice scattering and defects in the channel layer. In addition, the device on nitride with better memory characteristics has higher normalized drain current noise power spectral density ($S_{ID}/I^2_D$>), which means that it has more traps and defects in the channel layer. The apparent hooge's noise parameter (${\alpha}_{app}$) to represent the grain boundary trap density and the height of grain boundary potential barrier is considered. The device on nitride has higher ${\alpha}_{app}$ values, which can be explained due to more grain boundary traps. Therefore, the reason why the devices on nitride and oxide have a different P/E speed can be explained due to the trapping/de-trapping of free carriers into more grain boundary trap sites in channel layer.

• Korean Journal of Ecology and Environment
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• v.49 no.3
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• pp.187-196
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• 2016

This study was performed to improve the foaming generated in the effluent of wastewater treatment plant from March 2015 to July 2016. The main cause of foaming was air entrainment by an impinging jet and the internal accumulation by the diffusion barrier. Particularly, the foam growth was most active when there is low tide and larger discharge. To solve this problem, we experimented after installing fine mesh screen and the artificial channel device with underwater discharging outlet in the treated wastewater discharge channel and the outlet, respectively. As a result, the effects of foam reduction by devices ranged 85.0~92.0% and 70.7~85.6%, respectively. In addition, the foam and the noise were easily solved, first of all look to contribute to the prevention of complaints. Our device studies were applied to a single wastewater treatment plant. However, it is considered to be able to apply in other similar cases of domestic sewage treatment plants.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.4
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• pp.305-313
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• 1996

CTD measurements were conducted in the Nakdong estuary on the several sections or along-plume and cross-plume directions in 1993 and 1994. Internal Froude number Fi=0.22-0.35 in ebb tides and 0.14 in flood tides suggest that Nakdong river plume may go farther seawards in the along-plume direction with little mixing with the adjacent sea water after the construction of Nakdong river barrier. From Dadae-Po to Gaduk-Do section of cross-plume direction, three cores of low salinity were found. The main plume outflows from the newly made channel by cutting Ulsuk-Do after the construction of barrier. The low salinity core found near Gaduk-Do is the plume patch advected by tidal currents. Rossby deformation radius varied with the tidal cycle so that Coriolis effect is strengthened in flood tides to deepen the isohalines westwards to the Gaduk-Do site. Internal wavelike shape was found in the section of cross-plume direction during ebb tides. Richardson number of the section suggests the possibility of forming internal wave but more precise observations are necessary.

• Journal of Korea Water Resources Association
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• v.49 no.12
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• pp.1035-1044
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• 2016

In joint portions of the levee and the barrier, complex 3-dimensional flow was generated and collapse of revetment occurred frequently. For these reasons, it is necessary to install the joint revetment with greater stability as compared with the general revetment at the joint portions. However, design criteria for joint revetment was not presented in River Design Criteria (KWRA, 2009). Therefore it is necessary to research for engineering design of the joint revetment. In this study, hydraulic experiments were performed under various flow conditions in order to realize the collapse conditions of riprap and carried out in 20.0 m straight open channel with one side levee and the width was 4.0 m. The diameter of riprap covered around joint revetment was 0.03 m and the inlet discharges were $0.5{\sim}0.8m^3/s$. The numerical simulations were performed under same conditions with experiment. as results of this numerical simulations, the influence range was confirmed from the distribution of flow characteristics and shear stress. As a result, the riprap diameter of the joint revetment was calculated from 4.1 to 6.9 times greater than that of general revetment. As the inlet discharge was large, the range of vulnerable area was developed long in the downstream direction despite of same withdrawal velocity of riprap. Through this study, the methods of calculating the riprap diameter and influence range were proposed according to hydraulic characteristics of flow around joint revetment. At a later study, if additional experiments about effect of flood plane and various types of barrier is applied, it is expected that rational design method with stability of joint revetment can be proposed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.11 s.353
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• pp.1-7
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• 2006

3-dimensional(3-D) simulations of ideal double-gate bulk FinFET were performed extensively and the electrical characteristics. were analyzed. In 3-D device simulation, we changed gate length($L_g$), height($H_g$), and channel doping concentration($N_b$) to see the behaviors of the threshold voltage($V_{th}$), DIBL(drain induced barrier lowering), and SS(subthreshold swing) with source/drain junction depth($X_{jSDE}$). When the $H_g$ is changed from 30 nm to 45nm, the variation gives a little change in $V_{th}$(less than 20 mV). The DIBL and SS were degraded rapidly as the $X_{jSDE}$ is deeper than $H_g$ at low fin body doping($1{\times}10^{16}cm^{-3}{\sim}1{\times}10^{17}cm^{-3}$). By adopting local doping at ${\sim}10nm$ under the $H_g$, the degradation could be suppressed significantly. The local doping also alleviated $V_{th}$ lowering by the shallower $X_{jSDE}\;than\;H_g$ at low fin body doping.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.111-121
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• 2012

In this paper, a poly-Si thin film transistor with ${\sim}0.5{\mu}m$ gate length was fabricated and its electrical characteristics are optimized. From the results, it was verified that making active region with larger grain size using low temperature annealing is an efficient way to enhance the subthreshold swing, drain-induced barrier lowering and on-current characteristics. A SONOS flash memory was fabricated using this poly-Si channel process and its performances are analyzed. It was necessary to optimize O/N/O thickness for the reduction of electron back tunneling and the enhancement of its memory operation. The optimized device showed 2.24 V of threshold voltage memory windows which coincided with a well operating flash memory.

• Korean journal of communication and information
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• v.48
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• pp.63-89
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• 2009

The contents provided by the terrestrial broadcasters have governed the market based on their excellent quality in Korea. In spite of the launching of various pay TV services focusing on multi-channel, it is not yet easy to find out the substitutionary pay TV channels for the terrestrial. Therefore, the real time retransmission of the terrestrial channels brings about the crucial effects on the pay TV's competency, especially on the new media as the invisible barrier. So it is frequently proposed to change the aim of the retransmission policy from the universal access to the promotion of media industries. The retransmission can be divided into two types as the must carry and retransmission consent. In Korean situation, keeping or reducing the must carry channel would be appropriate rather than expanding them. However, periodic investigation into the public effects of the must carry is necessary, instead of it. Moreover, the rational and fair monetary compensation for the commercial channels(MBC, SBS, KBS2) is arising as the bottle neck in the retransmission agreements between the broadcasters. The conjoint analysis was carried out to estimate the welfare growth from the retransmission, based on the stated preference from the audiences' point of view. For must carry channels, it was certified as the 'win-win' strategy for both sides and audiences. For the commercial channels, it is revealed to be beneficial to the audiences. Thereafter, the standards for the rational price were suggested to promote the retransmission. This can contribute for inspiring the dynamic vitality to the media industry by reinforcing the contents competencies and for establishing the long term growth strategies.

• Ecology and Resilient Infrastructure
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• v.6 no.3
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• pp.154-162
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• 2019

Lateral connectivity between the channel and the floodplains has been damaged by the levee construction and channelization in most streams of South Korea. The purpose of this study was to develop a technique for easily and remotely assessing lateral connectivity using GIS in the streams and to evaluate the effectiveness of the assessment method by applying it to Cheongmi-cheon Stream, a representative stream in the central Korean Peninsula. The metrics of the lateral connectivity assessment are composed of (1) existence of remaining wetlands and (2) land use property as a habitat quality of the former floodplain outside the levee and (3) existence of levee barrier, (4) connectivity to the stream and (5) connectivity to the upland natural habitats as a connectivity from the channel through floodplain to the upland forest. According to the result of applying the assessment method to Cheongmi-cheon Stream, the lateral connectivity was severely damaged due to the levee construction and land use change in the former floodplain. The GIS-based assessment of the lateral connectivity developed in this study is expected to be used as a useful tool for identifying limitations of current connectivity in various attempts to restore lateral connectivity in riparian ecosystems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1097-1103
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• 2015

In order to build network infrastructure to implement the aforementioned advantages enabling smart device users to work anywhere, professional support and expensive VPN devices are required. This is a barrier to supplying VPN devices to small and medium-sized institutes. To address this issue, this study aims to implement OpenVPN, OpenSSH and iproute based on the OpenWRT platform which is an embedded OS for open networks in affordable open wired/wireless gateway H/W platforms to support the inter-network VPN. In addition, the network environment can be maintained optimal by applying a "multi-queuing real-time traffic shaping technology" to VPN tunnels, although channel quality changes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7B
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• pp.668-678
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• 2006

In designing a video-on-demand (VoD) system, one of the major challenges is how to reduce the viewer's waiting time maintaining a given bandwidth allocation and how to reduce the client's buffer requirements. To solve these problems, many VoD schemes were proposed. However, most VoD schemes require managing many segments of a video, frequency channel hopping, and using many channels at the same time. Therefore, to the complexity is a barrier to implementation. In this paper, we propose a fast staggered broadcasting scheme which has a simple structure and substantially improved VoD efficiency. The numerical results demonstrate that the viewer's waiting time of the fast staggered broadcasting scheme is close to the fast broadcasting scheme and the buffer requirements of this can be adapt for demanding rate by adjusting the short front part of a video sizes.