• The Journal of the Korea Contents Association
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• v.8 no.11
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• pp.18-24
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• 2008

An organic light-emitting diode(OLED) has advantages of low power driving, self light-emitting, wide viewing angle, excellent high resolution, full color, high reproduction, fast response speed, simple manufacturing process, or the like. However, there are still a number of challenges to get over in order to put it to practical use as a high performance display. First of all, the most important thing is to improve the efficiency of the OLED element in order to commercialize it. To this end, its efficiency can be improved by lowering the driving voltage through the improvement of structure of the OLED element and the application of new organic substance. Therefore, in this study, we have manufactured a red OLED element by applying fluorescent dyes to the emitting layer of the element having the structure of ITO/TPD/ Znq2+DCJTB /Znq2/Al and the structure of ITO/CuPc/NPB/ Alq3+DCJTB/Alq3/Al, in order to light-emitting various colors or improve the brightness and the efficiency, and then we have evaluated its electrical and optical characteristics.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.3
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• pp.389-395
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• 2013

Ethernet is the most widely deployed access network protocol around the world. IEEE 802.3az WG released the EEE standard based on LPI mode to improve the energy efficiency of Ethernet. This paper proposes improved adaptive power control mechanism that can enhance energy-efficiency based on EEE from small Ethernet switch. The feature of this mechanism is that it predicts the traffic characteristic of next cycle by measuring the amount of traffic flowing in during certain period and adjusts the optimal threshold value to relevant traffic load. Performance evaluation results indicate that the proposed mechanism improves overall performance compared to traditional mechanism, since it significantly reduces energy consumption rate, even though average packet delay increases a little bit.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1283-1284
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• 2008

염료감응형 태양전지는 투명성과 광입사각 둔감성 등의 장점을 바탕으로 미래 태양전지 시장을 주도할 수 있을 것으로 기대되고 있다. 이러한 염료감응형 태양전지의 실용화를 위해서는 고효율 연구뿐만 아니라 대면적화를 통한 용량의 증대 연구도 요구된다. 본 연구에서는 금속 재료로 염료감응형 태양전지 내에 그리드 전극을 삽입함으로써 전자 및 홀의 이동 개선과 확산 이동의 최소화에 의한 손실 감소를 통해 효율 향상을 시도했다. 또한, 투명전극의 레이저 식각을 통해 염료감응형 태양전지의 내부 저항 중 큰 비중을 차지하는 투명전극의 표면 저항도 줄이고자 했다. SEM을 통해 투명전극의 식각 상태를 확인하고, radio frequency 스퍼터를 통해 그리드 전극을 증착한 결과, 기존 셀보다 향상된 출력전류 및 fill factor를 얻을 수 있었고, 약 1%의 효율 증가를 확인할 수 있었다.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.9
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• pp.305-316
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• 2022

With the flood of digital data owing to the Internet of Things and big data, cloud service providers that process and store vast amount of data from multiple users can apply duplicate data elimination technique for efficient data management. The user experience can be improved as the notion of edge computing paradigm is introduced as an extension of the cloud computing to improve problems such as network congestion to a central cloud server and reduced computational efficiency. However, the addition of a new edge device that is not entirely reliable in the edge computing may cause increase in the computational complexity for additional cryptographic operations to preserve data privacy in duplicate identification and elimination process. In this paper, we propose an efficiency-improved duplicate data elimination protocol while preserving data privacy with an optimized user-edge-cloud communication framework by utilizing a trusted execution environment. Direct sharing of secret information between the user and the central cloud server can minimize the computational complexity in edge devices and enables the use of efficient encryption algorithms at the side of cloud service providers. Users also improve the user experience by offloading data to edge devices, enabling duplicate elimination and independent activity. Through experiments, efficiency of the proposed scheme has been analyzed such as up to 78x improvements in computation during data outsourcing process compared to the previous study which does not exploit trusted execution environment in edge computing architecture.

• Journal of the Korean Society for information Management
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• v.33 no.1
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• pp.225-245
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• 2016

The purpose of this study is to enhance the efficiency of library space usage through analyzing users' behavior in an academic library. Diary methodology was applied for collecting users' activities in the library. 108 students participated in this study, but 84 students submitted their diaries. Among them, 14 participants were interviewed to identify barriers and their needs in using the library. The findings suggest rearranging IT devices to increase use rate of those devices, making plans for reusing the space where it is rarely used, and improving the accessibility of information through browsing in the bookstack area. Additionally, time analysis of users' activities was used to analyze students' behavior in the library.

• Journal of Satellite, Information and Communications
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• v.4 no.1
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• pp.21-27
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• 2009

In this paper, we introduce a simulation result of cross ambiguity function (CAF) using time difference of arrival and frequency difference of arrival. This method is generally used to find a geographical location of the unknown radio transmitter. If multiple signals with the same source information are arrived at a receiver via different paths, then they will have different time delays and Doppler shifts. We can estimate the CAF by using these characteristics, and estimate the location of the unknown transmitter. This paper introduces a technique to improve the estimation performance of CAF.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.349-350
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• 2006

정부의 배전분할 유보결정에 따라 전력거래소에서는 현행 발전경쟁시장의 효율성 향상을 위한 많은 사업을 추진하고 있다. 그중 우선적으로 추진하였던 사업이 도매전력시장을 대비해 구축한 시장운영시스템(MOS; Market Operation System)을 현행 계통운영을 담당하고 있는 급전 자동화시스템(EMS; Energy Management System)과의 연계활동이다. 이는 시장운영시스템(MOS)에 내재되어 있는 최첨단 기능중에서 일부를 현행 전력시장에 적용함으로써 계통운영의 효율성 향상뿐만 아니라 계통운영기술을 선진화하는 것이다. 특히, 기존 급전시스템에 비해 가장 두드러지는 점은 발전기들에 대한 에너지 및 예비력 급전계획을 사전적으로 5분단위로 최적화하여 수립하고 이를 발전기들에게 송신함으로써 경제적이며 안정적인 전력계통운영을 가능하게 해 줄 수 있는 것이다. 이를 가능하게 하기 위해서는 바로 정확한 미래 수요수준의 결정이 필수불가결한 요소이다. 따라서 본 논문에서는 MOS-EMS 연계활용에서의 실시간 수요예측의 중요성과 기존 제작사의 알고리즘과 국내 전력수요특성간의 불일치점 그리고 이를 해결하고자 모색했던 방안들에 대하여 설명하고자 한다.

• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.229-235
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• 2014

Improving the time and cost efficiency of production systems is one of the important means of building competitive advantage and staying profitable in the ever increasing competitive business environment. Among others, CONWIP (constant work-in-process) and DBR (drum-buffer-rope) methods are widely used in improving production process efficiency. In this study, we have developed simulation models for a real button factory production system. We have tried to improve the efficiency of the production process by implementing these two approaches to our model. According to our results, both CONWIP and DBR production approaches were found to have equivalently better results in reducing the waiting time of the bottleneck process. By applying either of the two production systems, efficiency of the real production process can be significantly improved as the simulated model results demonstrate.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.345-346
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• 2015

본 논문은 30kW, 95GHz 자이로트론을 구동하기 위한 50kV, 100kW 출력의 Cathode Power Supply(CPS) 설계에 대해 기술한다. 자이로트론 구동 시스템의 신뢰성과 효율성 향상을 위해 고효율 공진형 컨버터 토폴로지를 이용한 3개의 컨버터 모듈을 기반으로 출력단이 직렬로 구성된 모듈의 3상 운전을 통해 낮은 출력 전압 리플과 함께 아크 발생 시 부하 단으로 전달되는 에너지를 최소화 할 수 있도록 CPS를 설계한다. 또한 고전압 전원장치의 절연에 대한 신뢰성 확보와 전력밀도 향상을 위한 변압기 및 정류부의 효율적인 절연 설계 및 구현에 대하여 기술한다. 설계된 CPS의 실험결과를 통해 30kW, 95GHz 자이로 트론을 구동하기 위한 전원장치 설계의 타당성과 우수성을 검증한다.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.403-407
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• 2003

A basic concept of TAS(Tractor Appointment System), which not only enhances the terminal productivity, but also yields higher efficiency of domestic CT(Container Terminal), is developed in this paper for CT to more competitive and serviceable. To analyze the effects of TAS when applied to the existing four-tier CT, a quantitative analysis is performed. The results showed that the number of rehandling time of CT has been significantly decreased, the efficiency of CT increased, and the flow time of trucks in CT reduced in a great deal