• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.1119-1143
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• 2014

Lightweight trust mechanism with lightweight cryptographic primitives has emerged as an important mechanism in resource constraint wireless sensor based mobile devices. In this work, outlier detection in lightweight Mobile Ad-hoc NETworks (MANETs) is extended to create the space of reliable trust cycle with anomaly detection mechanism and minimum energy losses [1]. Further, system is tested against outliers through detection ratios and anomaly scores before incorporating virtual programmable nodes to increase the efficiency. Security in proposed system is verified through ProVerif automated toolkit and mathematical analysis shows that it is strong against bad mouthing and on-off attacks. Performance of proposed technique is analyzed over different MANET routing protocols with variations in number of nodes and it is observed that system provide good amount of throughput with maximum of 20% increase in delay on increase of maximum of 100 nodes. System is reflecting good amount of scalability, optimization of resources and security. Lightweight modeling and policy analysis with lightweight cryptographic primitives shows that the intruders can be detection in few milliseconds without any conflicts in access rights.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.497-498
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• 2008

모바일 폰에서 IrDA를 통하여 개인정보 (전화번호부, 동영상, 사진등) 송수신시 IrMC, IrOBEX 그리고 HDLC 프로토콜 기반위의 IrLAP등의 프로토콜 스택을 사용하고 있다. Primary, secondary 두 mobile phone 간에 IrLAP layer의 payload data 송수신시 이용되는 3가지 physical layer schemes 중 전송속도 1l5.2kbps data rate의 제안된 표준인 Asynchronous(Async) frame 방식을 이용한다. [1] 현재의 모바일 폰에서는 Async frame scheme을 구현하기 위한 인터페이스 방식 중 UART 인터페이스를 이용하여 구현하고 있다. 현 모바일 폰에 이미 구현 되어 있는 기존 UART의 FIFO 제어 방법과 Interrupt service routine의 제어 알고리즘을 개선하여 기존 제어 방식과 비교하고 향상된 성능의 결과는 Throughput로 도출한다. 현 모바일 폰에서 사용자가 개인 정보 data등을 저장할 수 메모리 공간이 점점 늘어나고 있는 추세이다. Camera의 해상도 현 5Mega pixel까시 지원되고 동영상 파일 등도 근거리 무선통신인 IrDA로 송수신할 수 있으므로 본 성능비교 file의 size는 100Mega 이상도 비교할 수 있도록 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.794-799
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• 2015

To manage cell outage problem in indoor wireless communication systems, we should resolve the problem of abrupt network failure quickly. In this paper, we propose a near-optimal cell outage management (NoCOM) scheme to support seamless services to users. In consideration of system throughput, user fairness, and the guarantee of QoS simultaneously, the NoCOM scheme finds the solution of subchannel and power allocations using a non-convex optimization technique and allocates radio resources to users iteratively. Through intensive simulations, we verify the outstanding performances of the proposed NoCOM scheme with respect to the average cell capacity, user fairness, and computational complexity.

• Interdisciplinary Bio Central
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• v.2 no.2
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• pp.1.1-1.8
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• 2010

Microdevices have been used as effective experimental tools for the rapid and multiplexed analysis of individual cells in single-cell assays. Technological advances for miniaturizing such systems and the optimization of delicate controls in micron-sized space homing cells have motivated many researchers from diverse fields (e.g., cancer research, stem cell research, therapeutic agent development, etc.) to employ microtools in their scientific research. Microtools allow high-throughput, multiplexed analysis of single cells, and they are not limited by the lack of large samples. These characteristics may significantly benefit the study of immune cells, where the number of cells available for testing is usually limited. In this review, I present an overview of several microtools that are currently available for single-cell analyses in two popular formats: microarrays and microfluidic microdevices. Then, I discuss the potential to study human immunology on the single-cell level, and I highlight several recent examples of immunoassays performed with single-cell microdevice assays. Finally, I discuss the outlook for the development of optimized assay platforms to study human immune cells. The development and application of microdevices for studies on single immune cells presents novel opportunities for the qualitative and quantitative characterization of immune cells and may lead to a comprehensive understanding of fundamental aspects of human immunology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.1027-1035
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• 2000

In this paper, we have proposed the optimum technique for wireless ATM (WATM) error control in indoor environment. As the optimum technique, the conventional concatenated FEC only is regarded as the efficient error control method for time-critical ATM traffic in AWGN, and the pilot symbol-added fading compensation with the concatenated FEC is required to optimize the WATM performance in fading environment. Also, the truncated Type- H hybrid ARQ technique will be developed for quality-critical ATM traffic in order to improve its throughput. Therefore, this paper presents the optimization of WATM performance in indoor environment by means of evaluating above techniques using theoretical analysis and simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4618-4639
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• 2018

One of the most innovative paradigms for the next-generation of wireless cellular networks is the cloud-radio access networks (C-RANs). In C-RANs, base station functions are distributed between the remote radio heads (RHHs) and base band unit (BBU) pool, and a communication link is defined between them which is referred as the fronthaul. This leveraging link is expected to reduce the CAPEX (capital expenditure) and OPEX (operating expense) of envisioned cellular architectures as well as improves the spectral and energy efficiencies, provides the high scalability, and efficient mobility management capabilities. The fronthaul link carries the baseband signals between the RRHs and BBU pool using the digital radio over fiber (RoF) based common public radio interface (CPRI). CPRI based optical links imposed stringent synchronization, latency and throughput requirements on the fronthaul. As a result, fronthaul becomes a hinder in commercial deployments of C-RANs and is seen as one of a major bottleneck for backbone networks. The optimization of fronthaul is still a challenging issue and requires further exploration at industrial and academic levels. This paper comprehensively summarized the current challenges and requirements of fronthaul networks, and discusses the recently proposed system architectures, virtualization techniques, key transport technologies and compression schemes to carry the time-sensitive traffic in fronthaul networks.

• Journal of Navigation and Port Research
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• v.34 no.9
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• pp.719-726
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• 2010

As the competition among the container terminals in Korea has become increasingly fierce, every terminal is striving to increase its investments constantly and lower its operational costs in order to maintain the competitive edge and provide satisfactory services to terminal users. The unreasoning behavior, however, has induced that substantial waste and inefficiency exists in container terminal production. Therefore, it is of great importance for the terminal to know whether it has fully used its existing infrastructures and that output has been maximized given the input. From this perspective, data envelopment analysis (DEA) provides a more appropriate benchmark. This study applies three models of DEA to acquire a variety of analytical results about the operational efficiency to the Korean container terminals. According to efficiency value analysis, this study first finds the reason of inefficiency. It is followed by identification of the potential areas of improvement for inefficient terminals by applying slack variable method and giving the projection results. Finally, return to scale approach is used to assess whether each terminal is in a state of increasing, decreasing, or constant return to scale. The results of this study can provide terminal managers with insight into resource allocation and optimization of the operating performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.228-232
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• 2002

The rise throughput and the stability in the device fabrication can be obtained by applying chemical mechanical polishing(CMP) process in 0.18 ${\mu}m$ semiconductor device. However it does have various problems due to the CMP equipment. Especially, among the CMP components, process variables are very important parameters in determining removal rate and non-uniformity. In this paper, We studied the DOE(design of experiment) method for the optimized CMP process. Various process variations, such as table and head speed, slurry flow rate and down force, have investigated in the viewpoint of removal rate and non-uniformity. Through the above DOE results, we could set-up the optimal process parameters.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.2
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• pp.61-74
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• 2014

In recent years, development of femtocells are receiving considerable attention towards increasing the network coverage, capacity, and improvement in the quality of service for users. In 3GPP LTE-Advanced (LTE-A) system, to efficiently utilize the bandwidth, femtocell and macro cell uses the same frequency band, but this deployment poses a technical challenge of cross-tier interference to macro users. In this paper, the novel quality of service based fractional power control (QoS-FPC) scheme under the heterogeneous networks environment is proposed, which considers the users priority and QoS-requirements during the power allocation. The proposed QoS-FPC scheme has two focal points: firs, it protects the macrocell users uplink communication by limiting the cross-tier interference at eNB below a given threshold, and second, it ensures the optimization of femtocell users power allocation at each power adjustment phase. Performance gain is demonstrated with extensive system-level simulations to show that the proposed QoS-FPC scheme significantly decreases the cross-tier intereference and improves the overall users throughput.

• Design & Manufacturing
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• v.2 no.1
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• pp.45-50
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• 2008

Micro channel is to fabricate desired pattern on the polymer substrate by pressing the patterned mold against the substrate which is heated above the glass transition temperature, and it is a high throughput fabrication method for bio chip, optical microstructure, etc. due to the simultaneous large area patterning. However, the bad pattern fidelity in large area patterning is one of the obstacles to applying the hot embossing technology for mass production. In the present study, stamper of cross channel with width $100{\mu}m$ and height $50{\mu}m$ was manufactured using UV-LiGA process. Micro channel was manufactured using stamper manufactured in this study. Also replicability appliance was evaluated for micro channel and factors affected replicability were investigated using Taguchi method.