• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.557-560
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• 2007

The durability of 80 kW class stack module was tested in hydrogen recirculation and non-recirculation systems with the condition of 300Amps (constant current mode) and hydrogen pulse purging (10 seconds close/0.8 seconds open). A localized membrane failure in the interfacial area between membrane and sub-gasket, carbon corrosion in cathode electrode, and Pt dissolution/extraction have been found through the post mortem analysis such as CV, Impedance, SEM, and so on. The main reason of these mechanisms will be discussed in this study.

• 연구논문집
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• s.31
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• pp.15-21
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• 2001

A thermoacoustic refrigerator has not only considerable feasibility but also commercial usability, because it has high reliability, lower vibration, no moving part. and easy construction. In the present study, the resonant characteristics of a thermoacoustic refrigerator, varying the length of resonant tube from 400mm to 850mm, were investigated to improve performance. In order to determine the optimum position of the stack in the resonant tube and the optimum frequency, the simple open-tube-type thermoacoustic refrigerator was constructed. Air was used as a coolant. In the fifth harmonic, the largest $\DeltaT$ was $52.6^{\circ}C$ at 827Hz, tube length of 400mm, and stack length of 40mm.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.554-557
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• 2008

In this study, two types of central flow distributor designs are presented and compared to obtain the optimal compact design which has the least flow resistance and the uniform flow distribution in a vehicular fuel cell stack. For effective and reliable prediction on the thermo-flow characteristics of the reactants flow over the entire fuel cell stack domain, open channel flow in the bipolar plates of the power generating cells were simulated by applying a simplified flow resistance model with an empirical porous concept. A number of case studies were performed to figure out an optimal configuration of a central flow distributor device in terms of the time-dependent thermo-flow behavior and load-dependent flow distribution. The results showed that the stable and load-independent thermo-flow uniformity is very design specific, which is closely associated with the design of central manifolding devices in order to achieve the enhanced volumetric power density and the reliable long-lasting operating of fuel cells.

• Convergence Security Journal
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• v.22 no.3
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• pp.13-18
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• 2022

With the rapid development of IT technology, integration with existing industries has led to an increase in smart manufacturing that simplifies processes and increases productivity based on 4th industrial revolution technology. Security threats are also increasing and there are. In the case of supply chain attacks, it is difficult to detect them in advance and the scale of the damage is extremely large, so they have emerged as next-generation security threats, and research into detection technology is necessary. Therefore, in this paper, we collect, store, analyze, and visualize logs in multiple environments in real time using ELK Stack and Sysmon, which are open source-based analysis solutions, to derive information such as abnormal behavior related to supply chain attacks, and efficiently We try to provide an effective detection method.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.1
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• pp.39-45
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• 2004

A 12-cell PEMFC stack was fabricated using the TiN-coated 316 stainless steel bipolar plates as substitute for the expensive and brittle graphite bipolar plates. Open cirtuit voltage and the maximum power of the stack was 12.08 V and 1.197 kW (199.5 A @ 6 V), respectively. Volumetric and gravimetric power density of the stack was calculated to be 373 W/L and 168 W/kg, respectively. Performance of each cell was quite uniform initially while degraded at a singnificantly different rate. During the 1,000 hr-operation at a constant load of 48 A, stack voltage decreased from 9.0 to 7.98 V at a degradation rate of 11 %/1,000 hr. However, degradation rate of each cell was in the wide rage from 1.2 to 31 %/1,000 hr.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.118-120
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• 2002

블루투스는 저 전력과 휴대성이 높은 특징을 갖는 단거리 무선 통신 기술이며 다양한 응용 범위를 지니고 있어 차세대 통신기술로 각광받고 있다. 이에 따라 다양한 블루투스서비스들의 요구가 증대되고 있고 이들의 개발에 필요한 프로토콜 스택의 중요성 또한 커지고 있다. 본 논문에서는 오픈소스 프로토콜 스택인 OpenBT를 블루투스 모듈과 호스트 사이에서 중요한 역할을 하는 HCI를 중심으로 분석하였으며 이를 기반으로 한 응용 프로그램의 구현 및 테스트에 관하여 논하였다

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.3
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• pp.105-112
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• 2017

PCI Express is a bus technology that connects the processor and the peripheral I/O devices that widely used as an industry standard because it has the characteristics of high-speed, low power. In addition, PCI Express is system interconnect technology such as Ethernet and Infiniband used in high-performance computing and computer cluster. PGAS(partitioned global address space) programming model is often used to implement the one-sided RDMA(remote direct memory access) from multi-host systems, such as computer clusters. In this paper, we design and implement a OpenSHMEM API based on PCI Express maintaining the existing features of OpenSHMEM to implement RDMA based on PCI Express. We perform experiment with implemented OpenSHMEM API through a matrix multiplication example from system which PCs connected with NTB(non-transparent bridge) technology of PCI Express. The PCI Express interconnection network is currently very expensive and is not yet widely available to the general public. Nevertheless, we actually implemented and evaluated a PCI Express based interconnection network on the RDK evaluation board. In addition, we have implemented the OpenSHMEM software stack, which is of great interest recently.

• Spatial Information Research
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• v.22 no.5
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• pp.1-8
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• 2014

Globally, mobile, cloud computing or big data are the recent marketable key terms. These trend technologies or paradigm in the ICT (Information Communication Technology) fields exert large influence on the most application fields including geo-spatial applications. Among them, cloud computing, though the early stage in Korea now, plays a important role as a platform for other trend technologies uses. Especially, mobile cloud, an integrated platform with mobile device and cloud computing can be considered as a good solution to overcome well known limitations of mobile applications and to provide more information processing functionalities to mobile users. This work is a case study to design and implement the mobile application system for geo-spatial image filtering processing operated on mobile cloud platform built using OpenStack and various open sources. Filtering processing is carried out using R environment, recently being recognized as one of big data analysis technologies. This approach is expected to be an element linking geo-spatial information for new service model development and the geo-spatial analysis service development using R.

• The Journal of Information Technology
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• v.5 no.1
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• pp.69-77
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• 2002

The Bluetooth is expected to be one of the most popular wireless telecommunication technology in the near future, and the protocol stack is essential to providing the various services with the Bluetooth-embedding systems or devices. The Bluetooth specification is an open, global specification defining the complete system, however, the protocol stack is usually implemented partly in hardware and partly as software running on its system, with different implementations partitioning the functionality between hardware and software in different ways. I investigate how to design and implement the Bluetooth protocol stack according to its specification. I focus on the HCI and the lower layer of the software protocol stack as a basic step for the development of our own protocol stack. As a result, paper provides how to partitioning the role of HCI layer, and how to implement the relationship between HCI packets, it's functionality and the flow control. Experiments show the discovering other Bluetooth devices and their connection. Furthermore experiments demonstrate the proper operation of data communication between the Bluetooth modules.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.259-261
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• 2012

클라우드 컴퓨팅은 정보가 인터넷 상의 서버에 영구적으로 저장되고 데스크탑이나 테이블 컴퓨터, 노트북, 벽걸이 컴퓨터, 휴대용 기기 등과 같은 클라이언트에는 일시적으로 보관되는 패러다임을 뜻한다. 가용성과 사용상의 편의에 대한 요구의 증가로 최근들어 빠른 속도로 발전하는 모습을 보이고 있다. 클라우드 컴퓨팅은 제공하는 서비스의 유형에 따라 IaaS(Infrastructure as a Service), PaaS(Platform as a Service), SaaS(Software as a Service)로 나뉜다. 이 중 IaaS는 인프라를 서비스로 제공하는 모델이다. 이를 구현한 오픈소스 클라우드 플랫폼으로 오픈스택과 클라우드 스택이 대표적이다. 시트릭스는 자사가 개발중인 클라우드 플랫폼인 클라우드스택을 아파치 라이센스로 전환하겠다고 발표했다. 이전까지 같은 종류의 클라우드 플랫폼인 오픈스택의 회원사로 참여하고 있던 시트릭스가 오픈스택 그룹에서 탈퇴하고 클라우드스택을 지원한다는 발표는 큰 관심을 받았다. 본 논문에서는 여러 오픈소스 클라우드 플랫폼 중 오픈스택과 클라우드스택을 비교해보고, 이를 통해 향후 오픈소스 클라우드 플랫폼의 발전가능성에 대해 고찰해보고자 한다.