• Membrane Journal
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• v.26 no.5
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• pp.329-336
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• 2016

Proton exchange membrane (PEM) is one of the key components of membrane-electrode assembly (MEA), which plays important role in fuel cell performance together with catalysts. It is widely accepted that water channel morphology inside PEMs as a proton pathway significantly affects the PEM performance. Molecular dynamics (MD) simulations are a very useful tool to understand molecular and atomic structures of materials, so that many related researches are currently being studied. In this paper, we summarize the current research trend in MD simulations, present which properties can be characterized, and finally introduce the usefulness of MD simulations to the researchers for proton exchange membranes.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1173-1182
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• 2018

Mesoporous silica allows proper hydration of an ion exchange membrane under low relative humidity due to its strong hydrophilicity and structural characteristic. A mesoporous silica and Nafion composite membrane shows good proton conductivity under low relative humidity. An understanding of ion-channel formation and proton transfer through an ion-channel network in mesoporous silica and Nafion composite membranes is essential for the development and the optimization of ion exchange membranes. In this study, a mesoporous cellular foam $SiO_2/Nafion$ composite membrane is fabricated, and its proton conductivity and performance are measured. Also, the ion-channel distribution is analyzed by using electrostatic force microscopy to measure the surface charge density of the mesoporous cellular foam $SiO_2/Nafion$ composite membrane. The research reveals a few remarkable results. First, the composite membrane shows excellent proton conductivity and performance under low relative humidity. Second, the composite membrane is observed to form ion-channel-rich and ion-channel-poor region locally.

• Information and Communications Magazine
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• v.12 no.10
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• pp.31-40
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• 1995

최근 하드웨어와 컴퓨터 기술의 발전으로 인하여 전기통신망에서의 전송/교환 및 서비스 능력은 급속도로 증가하고 있다. 이러한 변화는 전송 및 교환기술에서 분명하게 나타나고 있다. 이러한 정보전달능력의 증가와 더불어 늘어나는 고객의 요구, 그리고 가속화되는 통신시장의 경쟁 등의 환경변화는 다양한 형태의 서비스를 단기간에 생성, 제공할 수 있으며 필요한 경우 최소한의 노력으로 기능의 추가 및 변경이 가능한 형태의 망관리 시스팀을 필요로 하게 되었다.이 경우 망관리 시스팀은 망 자원 관리기능 및 망 서비스 기능을 통합적으로 지원하는 형태를 갖는다. 본 논문에서는 위의 특성을 지닌 B-ISDN 통합 망관리 시스팀의 구조 및 기능에 관하여 기술한다. 먼저 목표 통합 망관리 시스팀의 구조를 명시하고 목표 시스팀으로의 진화를 지원하는 초기 단계 B-ISDN 관리 시스팀의 기능적 능력과 구조를 기술한다. 또한 이러한 구조에 근거한 ATM-Highway I의 구조를 설명한다. ATM-Highway I의 구조와 기능은 제안된 초기 망관리 시스팀구조에 근거하고 있으며, 목표 통합망관리 시스팀으로의 진화가 쉽게 이루어지도록 설계되어 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.27-28
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• 2020

이형 데이터 간의 정보 전송과 교환을 가능하게 하는 유연한 트리 구조의 특성은 인터넷 및 IoT 환경에서의 대량 데이터 저장·전송·교환 등에 있어서 XML이나 JSON에서 주요하게 사용된다. 사용성에 있어서는 수월한 반면에, 감추어져 있는 가치있는 정보들을 트리 구조의 대량 데이터들로부터 찾아내는 것은 일반 단순 구조의 데이터에 비해서 훨씬 어려우며 복잡하고 난해한 문제들을 발생시킨다. 이는 트리가 갖는 계층 구조 때문이다. 본 논문에서는 계층 구조를 갖는 대량 트리 데이터들을 보다 단순한 리스트 구조로 변형한 후 해당 구조로부터 가장 자주 발생하는 유용한 정보들을 추출하는 방법을 제시한다.

• Journal of the Korean Magnetics Society
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• v.20 no.2
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• pp.75-82
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• 2010

A recent progress on the prediction of the thermal stability of a nanostructured exchange-coupled trilayer is reviewed. An analytical/numerical combined method is used to calculate its magnetic energy barrier and hence the thermal stability parameter. An important feature of the method is the use of an analytical equation for the total energy that contains the magnetostatic fields. Under an assumption of the single domain state, the effective values of all the magnetostatic fields can be obtained by averaging their nonuniform values over the entire magnetic volume. In an equilibrium state, however, it is not easy to calculate the magnetostatic fields at the saddle point due to the absence of suitable methods of the accessing its magnetic configuration. This difficulty is overcome with the use of equations that link the magnetostatic fields at the saddle point and critical fields. Since the critical fields can readily be obtained by micromagnetic simulation, the present method should provide accurate results for the thermal stability of a nanostructured exchange-coupled trilayer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.1867-1879
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• 1997

DREAM-S is a distributed main-memory database system for the real-time processing of shared operational datra in ATM switching systems. DREAM-S has a client-server architecture in which only the server has the diskstorage, and provides the T-Tree index structure for efficient accesses to the data. We propose a recovery technique for the T-Tree index structre in DREAM-S. Although main-memory database system offer efficient access performance, the database int he main-memory may be broken when system failure such as database transaction failure or power failure occurs. Therfore, a recovery technique that recovers the database (including index structures) is essential for fault tolerant ATM switching systems. Proposed recovery technique relieves the bottleneck of the server processors disk operations by maintaining the T-Tree index structure only in the main-memory. In addition, fast recovery is guaranteed even in large number of client systems since the T-Tree index structure(s) in each system can be recovered cncurrently.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5B
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• pp.379-385
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• 2008

For the sharing and exchange of information between medical clinics, the clinical document has to be built on a standardized protocol such as a HL7-CDA. But it is difficult to exchange information between medical clinics because clinical document such as electronic medical record that include text and image, have different structure of document and type of expression. In this paper, we propose the electronic medical record system based on HL7-CDA that can share and exchange clinical information between medical institute. For this purpose, we have to design the schema of the clinical document architecture after we select the essential items of medical record and define templates. The proposed system can minimize integrating process and save parsing time when clinical information exchange and refer, by converting electronic medical record to base64 encoding scheme and integrate it in a XML document.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.223-229
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• 1992

Mechanistic studies on the metal-exchange reactions of sparteine copper(II) dichloride [$SpCuCl_2$] with Hg(II) ion and Hg(0) metal have been carried out with the aid of Cyclic Voltammetry and UV-visible spectrophotometry. The metal exchange reaction of $SpCuCl_2$ with both Hg(II) ion and Hg(0) metal follows pseudo-first order kinetics. Rate constants and activation parameters of metal exchange reaction have been evaluated and reported. Experimental results indicate that the rate determining step for the exchange reaction is the cleavage of Cu(II)-N bond in the transient binuclear complex of Cu(II) and mercury(II) bound to sparteine ligand.

• Journal of the Korean Chemical Society
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• v.55 no.1
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• pp.7-13
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• 2011

As an aid towards improving the treatment of exchange and correlation effects in electronic structure calculations, it is desirable to have a clear picture of concepts of exchange-correlation functionals in computational calculations. For achieving this aim, it is necessary to perform different theoretical methods for many groups of materials. We have performed hybrid density functional theory (DFT) methods to investigate the density charges of atoms in rings and cages of carbon nanotube. DFT methods are engaged and compared their results. We have also been inclined to see the impression of exchange and correlation on nuclearnuclear energy and electron-nuclear energy and kinetic energy. With due attention to existence methods, B3P86, B3PW91, B1B96, BLYP and B3LYP have used in this work.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.136-139
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• 2011

통합 플랫폼의 연계모듈은 구조시스템 대안생성, 구조해석, 구조설계를 수행하는 여러 프로그램들의 자료교환을 지원하는 모듈로서, buildingSMART International에서 개발한 표준자료모델을 기반으로 한다. 이 표준자료모델은 다양한 건축물의 기획부터 유지관리 단계까지를 대상으로 하므로 많은 자료들이 복잡하게 얽혀있어 그 전체적인 구조와 상세한 내용을 파악하기 곤란하다. 그러므로 통합 플랫폼의 여러 프로그램들에 표준자료모델 기반의 자료교환 기능 추가에는 많은 시간과 노력이 소요된다. 이에 본 연구에서는 이러한 시간과 노력을 절감할 수 있는 연계모듈 구조를 제안하고 이를 일부 구현하였으며, 간단한 적용사례를 통하여 타당성을 검토하였다.