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An efficient synchronization signal structure for OFDM-based cellular systems
Ilgyu Kim,Youngnam Han,Hyun Chung IEEE 2010 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.9 No.1
<P>OFDM has been a widely accepted technology in high rate and multimedia data service systems such as long term evolution (LTE) in the 3rd generation partnership project (3GPP). In this paper, we investigate a synchronization signal structure and corresponding cell search algorithm in the LTE system where two, primary and secondary synchronization signals are employed. We focus on the secondary synchronization signal which possesses two layered scrambling sequences in addition to basic sequences. These scrambling sequences minimize performance degradation in cell search, but incur a high complexity to a mobile station receiver. In this paper, we propose a new secondary synchronization signal structure which does not require additional scrambling sequences while maintaining almost the same performance as the current LTE scheme. We evaluate the performance of the proposed scheme under various channel environments by examining the impacts of multipath fading, frequency offset, and vehicular speed. We also compare the complexity of the proposed scheme with the LTE scheme.</P>
( Ilgyu Kim ) 서울대학교 법학연구소 2013 Journal of Korean Law Vol.12 No.2
Due to its exclusive nature of intellectual property rights, there have been numerous tensions between intellectual property and human rights. In order to reconcile those tensions, many different kinds of efforts, especially in the area of patent, have been made, which include legislative, licensing, and policy-based approaches. However, one of the best ways to acquire accessibility to technologies without legal constraint is to use technologies in the public domain. Many life-improving technologies that people in least developed countries (LDCs) need might be found in patent documents under public domain, because not only many patents are expired way before their legally allowed protection term of twenty years, but also technologies which impoverished people need usually may not be the technologies which were recently patent granted. In addition, many of patented technologies in developed countries are not usually filed at LDCs. Recent projects conducted by the Korean Intellectual Property Office and World Intellectual Property Organization show how to utilize patent information in assisting impoverished people in LDCs, which might be another reconciliatory way of tensions between developed and developing countries regarding patent system.
장일규 ( Ilgyu Jang ),유길종 ( Giljong Yoo ),이은석 ( Eunseok Lee ) 한국정보처리학회 2010 한국정보처리학회 학술대회논문집 Vol.17 No.2
현대의 시스템들은 매우 복잡해지고 있으며 그 규모 또한 점점 커지고 있다. 또한 기술의 발달로 서로 상호작용하는 시스템들이 많아졌으며, 비즈니스적 요구 사항의 증가로 인해 통합되는 시스템들도 많아지고 있다. 시스템의 유지 보수는 비용과 노력 등 시간이 갈수록 고객과 개발자에게 더 많은 부담이 되고 있다. 때문에 자율 컴퓨팅 시스템이 제안되었다. 자율 컴퓨팅 시스템은 시스템 스스로가 자신을 관리하는 자가 적응하는 시스템이다. 이러한 자율 컴퓨팅이 이루어 지기 위해서는 데이터베이스화 된 시스템의 결함 정보, 각 결함에 따른 하나 이상의 전략이 존재하여 적절한 선택을 할 수 있도록 하여야 한다. 본 논문은 OCL 을 기반으로 하여 설계 단계의 시스템 모델에서 예상 가능한 결함 정보를 추출하여 결함 리스트를 생성하는 연구를 내용으로 한다. 이를 통하여 개발자는 효율적으로 자가 적응 시스템을 구축할 수 있다. 그리고 연구의 효율성을 검증하기 위해 ATM 시스템을 대상으로 평가를 한다.
Lee, Ilgyu,Han, Jong-In Elsevier 2015 Bioresource technology Vol.186 No.-
<P><B>Abstract</B></P> <P>Simultaneous treatment (combining with cell disruption and lipid extraction) using hydrodynamic cavitation (HC) was applied to <I>Nannochloropsis salina</I> to demonstrate a simple and integrated way to produce oil from wet microalgae. A high lipid yield from the HC (25.9–99.0%) was observed compared with autoclave (16.2–66.5%) and ultrasonication (5.4–26.9%) in terms of the specific energy input (500–10,000kJ/kg). The optimal conditions for the simultaneous treatment were established using a statistical approach. The efficiency of the simultaneous method was also demonstrated by comparing each separate treatment. The maximum lipid yield (predicted: 45.9% and experimental: 45.5%) was obtained using 0.89% sulfuric acid with a cavitation number of 1.17 for a reaction time of 25.05min via response surface methodology. Considering its comparable extractability, energy-efficiency, and potential for scale-up, HC may be a promising method to achieve industrial-scale microalgae operation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Simultaneous treatment using HC was proposed to enhance the lipid yield. </LI> <LI> Optimal conditions for lipid extraction from <I>Nannochloropsis salina</I> were determined. </LI> <LI> HC was energy-efficient compared with autoclaving and ultrasonication. </LI> </UL> </P>
Design optimization of hydrodynamic cavitation for effectual lipid extraction from wet microalgae
Lee, Ilgyu,Oh, You-Kwan,Han, Jong-In Elsevier 2019 Journal of environmental chemical engineering Vol.7 No.2
<P><B>Abstract</B></P> <P>Design optimization of hydrodynamic cavitation (HC) was performed for the sake of maximally extracting internal lipids directly from wet microalgae. Different types of orifice plates (α = 2.5–10%; β = 1–10%) were designed for a HC system and examined in terms of cavity formation; and cavitation effect was demonstrated by way of lipid extraction from microalgae. Basic operating parameters of HC, such as flux, flow rate, and the number of rotation, were examined and based on them, the upper and lower limits of cavitation number identified to be 3.37 ± 0.01 (α = 2.5% and β = 1%) and 1.01 ± 0.00 (α = 7.5% and β = 1%), respectively. The maximum lipid extraction (46.0 ± 3.7%) was obtained at 5% of both α and β. A low β value resulted in high vapor pressure, which has a crucial effect on the cell disruption caused by the creation and extinction of cavities. Also, the number of treatment per minute through the orifice proved to be a crucial factor for cell disruption. On the other hand, a high α value caused a surge pressure driven by violent fluctuation of flow. The cavitation effects of HC were able to be well visualized in terms of pressure variation using CFD. This study showed that the HC is indeed a very promising cell disruptor and its effectiveness can be further enhanced by way of design optimization.</P> <P><B>Highlights</B></P> <P> <UL> <LI> HC was optimized with different orifice plates for algal lipid extraction. </LI> <LI> Maximum lipid yield was obtained at 5% of α and β. </LI> <LI> Cavitation number was found to be unrelated to lipid yield. </LI> <LI> Surge pressure issues could be minimized by using a properly designed orifice plate. </LI> <LI> Cavitation effect was realistically visualized via CFD. </LI> </UL> </P>
하향링크 다중사용자 다중안테나 시스템을 지원하는 반복 가중치 최소평균자승오류 빔형성 기법
최일규(Ilgyu Choi),황영수(Youngsoo Hwang),이충용(Chungyong Lee) 대한전자공학회 2013 전자공학회논문지 Vol.50 No.3
기존의 최소평균자승오류 빔형성 기법은 간섭제거나 정합필터 빔형성 기법보다 우수한 성능을 보여주지만, 전체 전송률의 증가를 목적으로 하지는 않는다. 본 논문은 전체 전송률을 가중된 평균자승오류로 표현하여 증가시키는 기법을 제안하였다. 제안 기법은 기존의 최소평균자승오류 기법에서 출발하여 반복적으로 가중치와 빔을 갱신함으로써 전체 전송률을 증가시킨다. 모의실험 결과를 통해 제안 기법이 기존 기법보다 전체 전송률 측면에서 뛰어나며, 기존 기법과 달리 사용자의 수가 높아질수록 전체 전송률이 증가하는 것을 확인하였다. Conventional MMSE beamforming scheme shows better performance than ZF or MF beamforming, but it does not aim increase of sum rate. This paper proposes sum rate maximizing scheme by representing sum rate as a function of weighted MSE. Proposed scheme increases sum rate iteratively by updating weights and beam whose initial form is conventional MMSE beam. Simulation result shows sum rate of proposed scheme is higher than those of conventional schemes and increases as the number of users increases.