• Title/Summary/Keyword: Deep current

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Threshold Current Reduction of GaAs/AlGaAs Quantum Cascade Laser due to the Deep Mesa Structure (GaAs/AlGaAs Quantum Cascade Laser에서 Deep Mesa 구조에 의한 문턱전류 감소)

  • Han, Il-Ki;Song, Jin-Dong;Lee, Jung-Il
    • Journal of the Korean Vacuum Society
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    • v.17 no.6
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    • pp.523-527
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    • 2008
  • GaAs/AlGaAs based quantum cascade lasers were fabricated with two different types of i) the shallow mesa type which was etched up to above active region and ii) the deep mesa type which was etched through active region. While the threshold current density of shallow mesa type was $26-32\;kA/cm^2$, the one of deep mesa type was reduced drastically up to $13\;kA/cm^2$. Such lowered threshold current density at deep mesa type attributed to the reduction of current loss to the lateral directions.

Consideration on the Preparation of Current Meters for Deep-sea Mooring and Cause of Mooring Recovery Failures (유속계 심해계류 준비 및 유속계 회수 실패원인에 관한 고찰)

  • Hwang, Sang-Chul
    • Ocean and Polar Research
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    • v.30 no.2
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    • pp.207-213
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    • 2008
  • An interest in deep-sea measurements has been gradually increased in association with global warming and the need for deep-sea resources development. Long-term mooring of current meters has been recently conducted primarily for these purposes. In general, current meters equipped on a mooring line are deployed and recovered for a planned period in the sea. This paper describes all the preparations for deep-sea mooring. It also reviews the possible causes of the failures of recovery, which occasionally happens in the sea.

A Review of Ocean Circulation of the East/Japan Sea (한국 동해 해수순환의 개략적 고찰)

  • 김종규
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2001.10a
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    • pp.103-107
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    • 2001
  • The major studies of an ocean circulation of the East/Japan Sea related to evaluate the feasibility and utilization of deep ocean water are reviewed. The major feature of surface current system of the East/Japan Sea is an inflow of the Tsushima Warm Current through the Korea/Tsushima Strait and the outflow through the Tsugaru and Soya Straits. The Tsushima Warm Current has been known to split into two or three branches in the southern region of the East/Japan Sea. In the cold water region of the East/Japan Sea, the North Korean Cold Current turns to the east near 39$^{\circ}$N after meeting the East Korean Warm Current, then flows eastward. The degree of penetration depends on the strength of the positive wind stress curl, according to the ventilation theory. Various current meter moorings indicate strong and oscillatory deep currents in various parts of the basin. According to some numerical experiments, these currents may be induced by pressure-topography or eddy-topography interaction. However, more investigations are needed to explain clearly the presence of these strong bottom currents. This study concludes the importance of topographical coupling, isopycnal outcropping, different wind forcing and the branching of the Tsushima Warm Current on the circulation of the East/Japan Sea.

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Deep-Learning-Based Molecular Imaging Biomarkers: Toward Data-Driven Theranostics

  • Choi, Hongyoon
    • Progress in Medical Physics
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    • v.30 no.2
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    • pp.39-48
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    • 2019
  • Deep learning has been applied to various medical data. In particular, current deep learning models exhibit remarkable performance at specific tasks, sometimes offering higher accuracy than that of experts for discriminating specific diseases from medical images. The current status of deep learning applications to molecular imaging can be divided into a few subtypes in terms of their purposes: differential diagnostic classification, enhancement of image acquisition, and image-based quantification. As functional and pathophysiologic information is key to molecular imaging, this review will emphasize the need for accurate biomarker acquisition by deep learning in molecular imaging. Furthermore, this review addresses practical issues that include clinical validation, data distribution, labeling issues, and harmonization to achieve clinically feasible deep learning models. Eventually, deep learning will enhance the role of theranostics, which aims at precision targeting of pathophysiology by maximizing molecular imaging functional information.

A Survey on Deep Convolutional Neural Networks for Image Steganography and Steganalysis

  • Hussain, Israr;Zeng, Jishen;Qin, Xinhong;Tan, Shunquan
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.3
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    • pp.1228-1248
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    • 2020
  • Steganalysis & steganography have witnessed immense progress over the past few years by the advancement of deep convolutional neural networks (DCNN). In this paper, we analyzed current research states from the latest image steganography and steganalysis frameworks based on deep learning. Our objective is to provide for future researchers the work being done on deep learning-based image steganography & steganalysis and highlights the strengths and weakness of existing up-to-date techniques. The result of this study opens new approaches for upcoming research and may serve as source of hypothesis for further significant research on deep learning-based image steganography and steganalysis. Finally, technical challenges of current methods and several promising directions on deep learning steganography and steganalysis are suggested to illustrate how these challenges can be transferred into prolific future research avenues.

Development of a Sensorless Deep Well Pump Multi-function Controller using Current Detection Method (전류검출 방식의 심정 펌프 센서리스형 다기능 컨트롤러 개발)

  • Lee, In-Jae;Basnet, Barun;Chun, Hyun-Jun;Bang, Jun-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.7
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    • pp.1149-1154
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    • 2017
  • In this paper, we propose a sensorless multi-function controller applicable for deep well water pumps using current detection method. The proposed system overcomes various drawbacks of existing sensored system and additional features like Over current protection function due to overload, Under current protection function for idling at low water level and Relay function for starting single phase motors and acts as a level indicator to detect water lever in real time by the current detection method. A prototype of the multi-function controller system is designed and all of its functions are tested in the laboratory. The application of the proposed controller ensures reduction in the power consumption and maintenance cost in the facilities like water and septic tanks, drainage and waste water system, oil and chemical tanks where deep well pumps are used.

Current Measurement and Velocity Spatial Distribution of Deep Ocean Engineering Basin

  • Jung, Sung-Jun;Jung, Jae-Sang;Lee, Yong-Guk;Park, Byeong-Won;Hwang, Sung-Chul;Park, In-Bo;Kim, Jin-Ha;Park, Il-Ryong
    • Journal of Ocean Engineering and Technology
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    • v.35 no.2
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    • pp.150-160
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    • 2021
  • To ensure the international competitiveness of the domestic offshore plant industry, a consensus has been formed regarding the requirement for large offshore basins for performing offshore plant performance verification. Accordingly, the Korea Research Institute of Ships & Ocean Engineering has built the world's largest deep ocean engineering basin (DOEB). The purpose of this study is to evaluate the characteristics of velocity distribution under various conditions of the DOEB. An independent measuring jig is designed and manufactured to measure the current velocities of many locations within a short time. The measurement jig is a 15-m-high triangular-truss structure, and the measurement sensors can move 15 m vertically through an electric motor-wire device. The current speed is measured under various impeller revolutions per minute and locations of the DOEB using the jig. The spatial distribution characteristics of the current velocity in the DOEB and the performance of the current generator are analyzed. The maximum speed is 0.56 m/s in the center of the DOEB water surface, thereby confirming sufficient current velocity distribution uniformity for model testing.

Hot carrier effects and device degradation in deep submicrometer PMOSFET (Deep submicrometer PMOSFET의 hot carrier 현상과 소자 노쇠화)

  • 장성준;김용택;유종근;박종태;박병국;이종덕
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.4
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    • pp.129-135
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    • 1996
  • In this paper, the hot carrier effect and device degradation of deep submicrometer SC-PMOSFETs have been measured and characterized. It has been shown that the substrate current of a 0.15$\mu$m PMOSFET increases with increasing of impact ionization rate, and the impact ionization rate is a function of the gate length and gate bias voltage. Correlation between gate current and substrate current is investigated within the general framework of the lucky-electron. It is found that the impact ionization rate increases, but the device degradation is not serious with decreasing effective channel length. SCIHE is suggested as the possible phusical mechanism for enhanced impact ionization rate and gate current reduction. Considering the hot carrier induced device degradation, it has been found that the maximum supply voltage is about -2.6V for 0.15$\mu$m PMOSFET.

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Abyssal Currents Driven by a Local Wind Forcing through Deep Mixed Layer: Implication to the East Sea

  • Seung, Young-Ho
    • Ocean Science Journal
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    • v.40 no.2
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    • pp.101-107
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    • 2005
  • A simple analytical model is considered in an attempt to demonstrate a formation mechanism of the abyssal current in the East Sea. In this model, the abyssal currents are driven by wind through an outcrop region and flow along closed geostrophic contours. A rough estimate of the abyssal currents, arrived at by applying this model to the region of deep mixing in the East Sea, gives currents comparable to those observed, although there is an uncertainty in the surface area of the outcrop region. It seems that the spin-up of deep water by wind forcing through the region of deep winter mixing is, at least partly, an important contribution to the formation of the abyssal currents in the East Sea.

Current Trend and Direction of Deep Learning Method to Railroad Defect Detection and Inspection

  • Han, Seokmin
    • International Journal of Internet, Broadcasting and Communication
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    • v.14 no.3
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    • pp.149-154
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    • 2022
  • In recent years, the application of deep learning method to computer vision has shown to achieve great performances. Thus, many research projects have also applied deep learning technology to railroad defect detection. In this paper, we have reviewed the researches that applied computer vision based deep learning method to railroad defect detection and inspection, and have discussed the current trend and the direction of those researches. Many research projects were targeted to operate automatically without visual inspection of human and to work in real-time. Therefore, methods to speed up the computation were also investigated. The reduction of the number of learning parameters was considered important to improve computation efficiency. In addition to computation speed issue, the problem of annotation was also discussed in some research projects. To alleviate the problem of time consuming annotation, some kinds of automatic segmentation of the railroad defect or self-supervised methods have been suggested.